[0001] The present invention relates to cellulosic fibrous structures having at least three
regions distinguished by intensive properties, and more particularly to paper having
relatively low basis weight decorative indicia and a method for making such paper.
BACKGROUND OF THE INVENTION
[0002] Cellulosic fibrous structures, such as paper, are well known in the art. Frequently,
it is desirable to have regions of different basis weights within the same cellulosic
fibrous product. The two regions serve different purposes. The regions of higher basis
weight impart tensile strength to the fibrous structure. The regions of lower basis
weight may be utilized for economizing raw materials, particularly the fibers used
in the papermaking process and to impart absorbency to the fibrous structure. In a
degenerate case, the low basis weight regions may represent apertures or holes in
the fibrous structure. However, it is not necessary that the low basis weight regions
be apertured.
[0003] The properties of absorbency and strength, and further the property of softness,
become important when the fibrous structure is used for its intended purpose. Particularly,
the fibrous structure described herein may be used for facial tissues, toilet tissue,
paper towels, bibs, and napkins, each of which is in frequent use today. If these
products are to perform their intended tasks and find wide acceptance, the fibrous
structure must exhibit and maximize the physical properties discussed above. Wet and
Dry Tensile strengths are measures of the ability of a fibrous structure to retain
its physical integrity during use. Absorbency is the property of the fibrous structure
which allows it to retain contacted fluids. Both the absolute quantity of fluid and
the rate at which the fibrous structure will absorb such fluid must be considered
when evaluating one of the aforementioned consumer products. Further, such paper products
have been used in disposable absorbent articles such as sanitary napkins and diapers.
[0004] Attempts have been made in the art to provide paper having two different basis weights,
or to otherwise rearrange fibers. Examples include U.S. Patent 795,719 issued July
25, 1905 to Motz; U.S. Patent 3,025,585 issued March 20, 1962 to Griswold; U.S. Patent
3,034,180 issued May 15, 1962 to Greiner et al; U.S. Patent 3,159,530 issued December
1, 1964 to Heller et al; U.S. Patent 3,549,742 issued December 22, 1970 to Benz; and
U.S. Patent 3,322,617 issued May 30, 1967 to Osborne.
[0005] Separately, there is a desire to provide tissue products having both bulk and flexibility.
Improved bulk and flexibility may be provided through bilaterally staggered compressed
and uncompressed zones, as shown in U.S. Patent 4,191,609 issued March 4, 1980 to
Trokhan, which patent is incorporated herein by reference.
[0006] Several attempts to provide an improved foraminous member for making such cellulosic
fibrous structures are known, one of the most significant being illustrated in U.S.
Patent 4,514,345 issued April 30, 1985 to Johnson et al., which patent is incorporated
herein by reference. Johnson et al. teaches hexagonal elements attached to the framework
in a batch liquid coating process.
[0007] Another approach to making tissue products more consumer preferred is to dry the
paper structure to impart greater bulk, tensile strength, and burst strength to the
tissue products. Examples of paper structures made in this manner are illustrated
in U.S. Patent 4,637,859 issued January 20, 1987 to Trokhan, which patent is incorporated
herein by reference. U.S. patent 4,637,859 shows discrete dome shaped protuberances
dispersed throughout a continuous network, and is incorporated herein by reference.
The continuous network can provide strength, while the relatively thicker domes can
provide softness and absorbency.
[0008] One disadvantage of the papermaking method disclosed in U.S. Patent 4,637,859 is
that drying such a web can be relatively energy intensive and expensive, and typically
involves the use of through air drying equipment. In addition, the papermaking method
disclosed in U.S. 4,637,859 can be limited with respect to the speed at which the
web can be finally dried on the Yankee dryer drum. This limitation is thought to be
due, at least in part, to the pattern imparted to the web prior to transfer of the
web to the Yankee drum. In particular, the discrete domes described in U.S. 4,637,859
may not be dried as efficiently on the Yankee surface as is the continuous network
described in U.S. 4,637,859. Accordingly, for a given consistency level and basis
weight, the speed at which the Yankee drum can be operated is limited.
[0009] Conventional tissue paper made by pressing a web with one or more press felts in
a press nip can be made at relatively high speeds. The conventionally pressed paper,
once dried, can then be embossed to pattern the web, and to increase the macro-caliper
of the web. For example, embossed patterns formed in tissue paper products after the
tissue paper products have been dried are common.
[0010] However, embossing processes typically impart a particular aesthetic appearance to
the paper structure at the expense of other properties of the structure. In particular,
embossing a dried paper web disrupts bonds between fibers in the cellulosic structure.
This disruption occurs because the bonds are formed and set upon drying of the embryonic
fibrous slurry. After drying the paper structure, moving fibers normal to the plane
of the paper structure by embossing breaks fiber to fiber bonds. Breaking bonds results
in reduced tensile strength of the dried paper web. In addition, embossing is typically
done after creping of the dried paper web from the drying drum. Embossing after creping
can disrupt the creping pattern imparted to the web. For instance, embossing can eliminate
the creping pattern in some portions of the web by compacting or stretching the creping
pattern. Such a result is undesirable because the creping pattern improves the softness
and flexibility of the dried web.
[0011] One problem with paper made according to prior teachings is that an excessive amount
of low basis weight regions can reduce the strength of the paper.
[0012] Accordingly, it is an object of this invention to overcome such problems, and and
particularly to overcome such problems as they relate to a single lamina of paper.
Specifically, it is an object of this invention to provide a paper web which has decorative
indicia formed by relatively low basis weight regions, without compromising the strength,
absorbency, and softness characteristics of the paper web.
[0013] Another object of the present invention is to provide a paper and method for making
a multi-region paper web wherein the web has a predetermined pattern of relatively
high and relatively low density regions, yet can be dried with relatively lower energy
and expense.
[0014] Another object of the present invention is to provide a method for making a multi-region
paper having relatively low basis weight decorative indicia which can be formed on
an existing paper machine (conventional or through air drying capability) without
the need for substantial modification of the papermaking machine.
[0015] Another object is to provide a paper web and method of making the paper web where
the web has decorative indicia comprising low basis weight regions for providing aesthetic
benefits, in combination with enhanced bulk caliper, bulk density, and absorbent capacity,
thereby providing both the properties of bulk and softness desired by consumers of
paper products.
[0016] WO-A-93/00475 discloses a paper web comprising discrete, relatively low basis weight
regions dispersed throughout a relatively high basis weight background portion in
a non-random, repeating pattern, wherein the background portion has at least one region
of relatively high density and at least one region of relatively low density.
BRIEF SUMMARY OF THE INVENTION
[0017] The present invention provides a paper web having oppositely facing surfaces and
at least three regions. The three regions are disposed in a nonrandom, repeating pattern
and are distinguishable from each other by at least one property selected from the
group consisting of basis weight, density, and fiber composition. The paper web comprises
decorative indicia, the decorative indicia comprising one or more regions having a
basis weight which is lower than the basis weight of at least a part of the surrounding
background portion of the web.
[0018] The term "decorative indicia" as used herein refers to a recognizable shape or shapes
imparted to the web, preferably during initial formation of the web. Such shapes include,
but are not limited to, floral shapes, animal shapes, geometric shapes, and the like.
The decorative indicia preferably comprise less than about 30 percent of the surface
area of the web, thereby enhancing the distinctiveness of the decorative indicia from
the background portion of the web.
[0019] The background portion of the web is selectively densified to provide a relatively
high density continuous network, and relatively low density regions dispersed throughout
the network. The relatively high density continuous network provides strength, and
the relatively low density regions provide bulk and absorbency.
[0020] In addition to the relatively low basis weight regions, the decorative indicia can
include relatively high basis weight regions. The relatively low basis weight regions
of the decorative indicia can enclose one or more cells having a basis weight substantially
equal to the basis weight of the background, or alternatively, a basis weight different
from that of the background. These relatively high basis weight cells can be encircled
by the relatively low basis weight regions. These relatively high basis weight cells
can be selectively densified to provide relatively high density regions and relatively
low density regions within the decorative indicia.
[0021] In one embodiment, the paper web comprises between about 5 and about 5000 decorative
indicia per square meter of the web. The relatively high basis weight background portion
of the web comprises a relatively high density continuous network region and at least
about 10,000 relatively low density regions per square meter of the web, the relatively
low density regions being dispersed throughout the continuous network region. The
background portion has a smoothness value of less than about 900 on at least one of
the oppositely facing surfaces of the web to provide a surface which is smooth and
soft to the touch.
[0022] The decorative indicia can comprise relatively low basis weight regions having a
basis weight which is between about 25 percent and about 75 percent of the basis weight
of the background portion surrounding the decorative indicia. The decorative indicia
can comprise relatively low basis weight regions having a basis weight which is less
than about 75 percent of the basis weight of the surrounding background portion. In
one embodiment, the decorative indicia can comprise relatively low basis weight regions
having a basis weight which is less than about 60 percent of the basis weight of the
surrounding background portion.
[0023] The paper web of the present invention has the advantage that the decorative indicia
provide consumer preferred aesthetics, yet the paper web maintains strength and absorbency
of multi-density paper. Moreover, the paper webs of the present invention have decorative
indicia and multi-density regions, yet can have a relatively smooth surface. The smooth
surface provides consumer preferred softness, and can help to visually distinguish
the decorative indicia. Additionally, the smooth surface surrounding the low basis
weight decorative indicia accentuates the distinctiveness of the relatively low basis
weight decorative indicia, thereby enhancing the aesthetic appearance of the web.
[0024] The present invention also provides a method for making a paper web having three
regions disposed in a nonrandom, repeating pattern and being distinguishable from
each other from at least one property selected from the group consisting of basis
weight, density, and fiber composition. The method comprises the steps of: providing
a plurality of cellulosic fibers suspended in a liquid carrier; providing a fiber
retentive forming element having liquid pervious zones; depositing the cellulosic
fibers and the liquid carrier onto the forming element; draining the liquid carrier
through the forming element in two simultaneous stages to form a web having at least
one relatively high basis weight region and decorative indicia comprising one or more
relatively low basis weight regions; providing a web support apparatus having a web
patterning surface; transferring the web from the forming element to the web patterning
surface of the web support apparatus; and selectively densifying at least a portion
of the relatively high basis weight region to provide a nonrandom, repeating pattern
of relatively high and low density regions in the relatively high basis weight region.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] While the Specification concludes with claims particularly pointing out and distinctly
claiming the present invention, it is believed the invention is better understood
from the following description taken in conjunction with the associated drawings,
in which like elements are designated by the same reference numeral and:
Figure 1A is a plan view illustration of a portion of a paper web made according to
the present invention, the Figure showing three decorative indicia.
Figure 1B is a enlarged plan view illustration of a single decorative indicia shown
in Figure 1A, and illustrating different crepe frequencies.
Figure 2 is a cross-sectional schematic illustration of a paper web of the type shown
in Figure 1B and taken along lines 2-2 in Figure 1B.
Figure 3 is a photograph of a portion of a paper web made according to the present
invention, the photo showing a single decorative indicia.
Figure 4 is a schematic illustration of a paper machine which can be used to make
the paper web of the present invention, the paper machine showing a paper web being
formed on a forming element and selectively densified on a web support apparatus.
Figure 5 is a photograph showing the sheet side of a forming element which can be
used to make a paper web of the present invention, the forming element including a
liquid permeable structure formed of woven filaments, and a patterned, liquid impermeable
photopolymer resin layer joined to the woven filaments to form a flow restriction
member corresponding to a decorative indicia.
Figure 6 is a plan view illustration of a portion of a forming element of the type
shown in Figure 5, the forming element in Figure 6 including four flow restriction
members.
Figure 7 is a cross-sectional schematic illustration showing an embryonic web supported
on a forming element of the type shown in Figure 6.
Figure 8 is a photograph showing the sheet side surface of a web support apparatus
in the form of a imprinting fabric comprising a felt layer and a patterned photopolymer
layer joined to the felt layer to provide a continuous network web imprinting surface.
Figure 9 is a plan view illustration of a portion of the sheet side of a web support
apparatus of the type shown in Figure 8.
Figure 10 is a cross-sectional schematic illustration showing the paper web transferred
to the web support apparatus of the type shown in Figure 9 to provide a paper web
having a first surface conformed to the apparatus and a second substantially smooth
surface.
Figure 11 is a schematic illustration showing a paper web being transferred to a Yankee
dryer.
Figure 12 is a plan view illustration of a paper web made according to an alternative
embodiment of the present invention, the paper web including discrete, decorative
indicia, and a relatively high basis weight background comprising a continuous network
region, discrete relatively low density regions dispersed throughout the network,
and discrete, relatively high density regions dispersed throughout each of the relatively
low density regions.
Figure 13 is a cross-sectional illustration of the paper web of Figure 12 taken along
lines 13-13 in Figure 12.
Figure 14 is a plan view illustration of an apparatus for use in making a paper web
of the type illustrated in Figure 12, the apparatus comprising a web patterning layer
joined to foraminous element formed of woven filaments.
Figure 15 is a cross-sectional illustration of the apparatus of Figure 14.
Figure 16 is an illustration of a papermachine for making a paper web with the apparatus
of Figures 14 and 15.
Figure 17 is an illustration showing a paper web transferred to the apparatus shown
in Figure 15 to form a paper web having a first surface conformed to the apparatus
and a second substantially smooth surface.
Figure 18 is an illustration of a paper web on the apparatus shown in Figure 15 being
carried between a pressure roll and a Yankee drying drum to impart a pattern to the
first surface of the paper web and to adhere the second surface of the paper web to
the Yankee drum.
DETAILED DESCRIPTION OF THE INVENTION
[0026] Figures 1A,B and 2 illustrate a paper web 20 made according to one embodiment of
the present invention, and Figure 3 is a photograph of a paper structure of the type
illustrated in Figures 1A,B and 2. The paper web is wetlaid, and is substantially
free of dry embossments.
[0027] Referring to Figures 1A,B and 2, the paper web 20 has first and second oppositely
facing surfaces 22 and 24, respectively. The paper web 20 comprises at least three
regions disposed in a nonrandom, repeating pattern. The three regions are distinguishable
from each other by at least one property selected from the group consisting of basis
weight, density, and fiber composition.
[0028] Figure 2 is a cross-sectional illustration of a portion of a paper web of the type
shown in Figures 1A, and 1B. The line density through the web thickness in Figure
2 is used to schematically illustrate the relative basis weights of different portions
of the web. The portions of the web illustrated with 5 lines through the web thickness
represent relatively high basis weight regions, and the portions of the web illustrated
with 3 lines represent relatively low basis weight regions.
[0029] The paper web 20 includes a relatively high basis weight background portion 100.
The paper web also includes discrete, visually distinctive decorative indicia 200
dispersed throughout the background portion 100 in a nonrandom, repeating pattern.
The decorative indicia 200 can be imparted to the web by selective drainage of water
from the web during formation of the web, as described in more detail below. The decorative
indicia comprise one or more relatively low basis weight regions 220. The regions
220 have a basis weight which is lower than the basis weight of the surrounding background
portion 100 of the paper web.
[0030] The relatively high basis weight background portion 100 is selectively densified
to have at least one high density region and at least one low density region. In the
embodiment shown in Figures 1A, 1B, and 2, the background portion 100 is selectively
densified to have a relatively high density, continuous network region 110 and a plurality
of discrete, relatively low density regions 130 dispersed throughout the continuous
network region 110. The regions 130 are relatively thicker than the region 110.
[0031] The relatively low basis weight regions 220 can have a closed path shape outlining
a plurality of adjacent, relatively higher basis weight cells 240. The basis weight
everywhere within each of the cells 240 is higher than the basis weight of the relatively
low basis weight regions 220 encircling the particular cell 240. Each cell 240 has
a perimeter formed by a closed loop portion of the relatively low basis weight regions
220.
[0032] In one preferred embodiment, each cell 240 has no more than half its perimeter with
any one adjacent cell 240. Preferably, at least some cells 240 are characterized in
having a perimeter such that any straight line drawn through the cell 240 intersects
the perimeter of the cell in no more than three locations. Without being limited by
theory, it is believed that such a cell geometery permits the decorative indicia 200
to be visually discernable and aesthetically pleasing without excessively reducing
the strength of the web 20.
[0033] The relatively high basis weight cells 240 can be selectively densified to provide
relatively high density regions and relatively low density regions. In Figure 1A and
1B, the relatively high basis weight cells 240 comprise a relatively high density,
continuous network 260 and discrete, relatively low density regions 280 dispersed
throughout the continuous network 260.
[0034] In one embodiment, the paper web 20 comprises between about 5 and about 5000 of the
decorative indicia 200 per square meter of the web, and most preferably between about
25 and about 1000 decorative indicia 200 per square meter of the web, in order to
enhance the distinction between the background 100 and the decorative indicia 200.
The relatively high basis weight background portion 100 of the web can comprise at
least about 10,000 relatively low density regions 130 per square meter of the web,
the relatively thicker low density regions being dispersed throughout the continuous
network region 110 to enhance the web's absorbency and bulk.
[0035] The background portion 100 has a smoothness value of less than about 900 on at least
one of the oppositely facing surfaces of the web. In Figure 2, the smoothness value
of surface 24 is less than the smoothness value of surface 22. The smoothness value
of surface 24 is preferably less than about 900. In particular, the paper web 20 can
have surface smoothness ratio greater than about about 1.15, more preferably greater
than about 1.20, even more preferably greater than about 1.25, still more preferably
greater than about 1.30, and most preferably greater than about 1.40, where the surface
smoothness ratio is the value of the surface smoothness of surface 22 divided by the
value of the smoothness value of surface 24.
[0036] In one embodiment, the surface 24 of the web 20 can have a surface smoothness value
of less than about 900, and more preferably less than about 850. The opposite surface
22 can have a surface smoothness value of at least about 900, and more preferably
at least about 1000.
[0037] The method for measuring the value of the surface smoothness of a surface is described
below under "Surface Smoothness." The value of surface smoothness for a surface increases
as the surface becomes more textured and less smooth. Accordingly, a relatively low
value of surface smoothness indicates a relatively smooth surface.
[0038] The regions 220 can have a basis weight which is less than about 75 percent of the
basis weight of the surrounding background portion 100. The relatively low basis weight
regions 220 can have a basis weight which is between about 25 percent and about 75
percent of the basis weight of the background portion 100.
[0039] In one embodiment, the regions 220 can have a basis weight which is less than about
60 percent of the basis weight of the surrounding background portion 100. The basis
weight of the background portion 100 can be between about 10 grams per square meter
and about 70 grams per square meter. The basis weight of the relatively low basis
weight regions 220 can be between about 5 grams/square meter and about 35 grams/square
meter.
[0040] The basis weight of the relatively low basis regions 220 is prefereably less than
about 20 grams/square meter and more preferably less than about 15 grams/square meter.
In one embodiment, the basis weight of the background portion 100 can be between about
10 grams/square meter and about 30 grams/square meter, and the basis weight of the
relatively low basis weight regions 220 can be between about 5 grams/ square meter
and about 15 grams/square meter. The basis weight of the regions 240 can be about
equal to the basis weight of the background portion 100.
[0041] The paper web of the present invention has the advantage that the decorative indicia
provide consumer preferred aesthetics, yet the paper web maintains strength and absorbency
of multi-density paper. Moreover, the paper webs of the present invention have decorative
indicia and multi-density regions, yet can have a relatively smooth surface. The smooth
surface provides consumer preferred softness. Additionally, the smooth surface surrounding
the low basis weight decorative indicia accentuates the distinctiveness of the relatively
low basis weight decorative indicia, thereby enhancing the aesthetic appearance of
the web.
[0042] The continuous network region 110 and the discrete regions 130 can both be foreshortened,
such as by creping. In Figures 1B, the crepe ridges of the continuous network region
110 are designated by numeral 115, and extend in a generally cross-machine direction.
Similarly, the discrete, relatively lower density and relatively thicker regions 130
can also be foreshortened to have crepe ridges 135.
[0043] The continuous network region 110 can be a relatively high density, macroscopically
monoplanar continuous network region of the type disclosed in U.S. Patent 4,637,859.
The relatively lower density and relatively thicker regions 130 can be bilaterally
staggered, as disclosed in U.S. patent 4,637,859. However, the regions 130 are not
domes of the type shown in U.S. Patent 4,637,859. The regions 130 are disposed in
the plane of the continuous network region 110, as disclosed in U.S. Patent Application
Serial Number 08/748,871 "Paper Web Having A Relatively Thinner Continuous Network
Region & Discrete Relatively Thicker Regions In the Plane of the Continuous Network
Region, filed November 14, 1996 in the name of Phan, which application is incorporated
herein by reference.
[0044] The paper web 20 having the relatively smooth surface 24 can be useful in making
a multiple ply tissue having smooth outwardly facing surfaces. For instance, two or
more webs 20 can be combined to form a multiple ply tissue, such that the two outwardly
facing surfaces of the multiple ply tissue comprise the surfaces 24 of the webs 20,
and the surfaces 22 of the outer plies face inwardly. Alternatively, a two ply paper
structure can be made by joining a web 20 of the present invention with a conventionally
formed and dried paper web. The web 20 can be joined to the conventional paper web
such that the surface 24 faces outwardly.
[0045] The paper web 20 can have a basis weight of about 10 to about 70 grams per square
meter. The paper web 20 can have a macro-caliper of at least about 0.1 mm, and more
preferably at least about 0.2 millimeter and a bulk density of less than about 0.12
gram per cubic centimeter (basis weight divided by macro-caliper, multiplied by an
appropriate conversion factor if units are not consistent). The procedures for measuring
the basis weight, macro-caliper, and bulk density of a web are described below.
[0046] The paper web 20 of the type shown in Figures 1-2 can also have an absorbent capacity
of at least about 15 grams per gram. The method for measuring the absorbent capacity
is described below. Accordingly, the paper web 20 exhibits the absorbency benefits
of high bulk paper webs, in combination with the benefits of a relatively smooth surface
usually associated with conventional felt pressed tissue paper.
[0047] Figure 3 is a photograph of surface 22 of a paper web 20 made according to the present
invention, showing a decorative indicia 200, the continuous network 110 and the discrete,
relatively lower density regions 130 of the background 100.
Papermaking Method Description
[0048] A paper structure 20 according to the present invention can be made with the papermaking
apparatus shown in Figures 4. The method of making the paper structure 20 of the present
invention is initiated by providing a plurality of fibers suspended in a liquid carrier,
such as an aqueous dispersion of papermaking fibers in the form of a slurry, and depositing
the slurry of papermaking fibers from a headbox 1500 onto a fiber retentive forming
element 1600. The forming element 1600 is in the form of a continuous belt in Figure
4. The slurry of papermaking fibers is deposited on the forming element 1600, and
water is drained from the slurry through the forming element 1600 to form an embryonic
web of papermaking fibers 543 supported by the forming element 1600. The slurry of
papermaking fibers can include relatively long fibers having an average fiber length
of greater than or equal to 2.0 mm, and relatively short fibers having an average
fiber length of less than 2.0 mm. For instance, the relatively long fibers can comprise
softwood fibers, and the relatively short fibers can comprise hardwood fibers. Hardwood
and softwood fibers are discussed in more detail below.
[0049] Figure 5 is photograph of the web facing side of a forming element 1600 suitable
for making a paper web 20 according to the present invention. Figure 6 is a schematic
illustration of the web facing side of a forming element 1600. Figure 7 is a cross-sectional
illustration of a forming element 1600 showing the embryonic web 543 deposited on
the web facing side of the forming element 1600.
[0050] The forming element 1600 comprises a liquid permeable woven base 1610 and flow restriction
members 1650 disposed on the woven base 1610. The woven base 1610 comprises machine
direction filaments 1612 and cross-machine direction filaments 1614. The flow restriction
members 1650 have a shape corresponding to the decorative indicia formed on the web
20. The woven base 1610 provides a first drainage zone corresponding to that portion
of the woven base 1610 which is not covered by the flow restriction members 1650.
The first drainage zone has a first drainage rate. The portion of the forming element
1600 on which the flow restriction members 1650 are disposed provides a second drainage
zone having a second drainage rate slower than the first drainage rate.
[0051] The liquid carrier (e.g. water) is drained through the forming element 1600 in two
simultaneous stages corresponding to the first and second drainage zones. Accordingly,
fibers in the aqueous slurry tend to flow from the second drainage zone and accumulate
in the first drainage zone, thereby forming relatively low basis weight regions in
registration with the flow restriction members 1650. The relatively shorter fibers
tend to accumulate in the first zone. At least some of the relatively longer fibers
can bridge the width of the flow restriction members. As a result, the average fiber
length of the papermaking fibers in the relatively low basis weight regions of the
decorative indicia is greater than the average fiber length of the papermaking fibers
in surrounding portions of the web.
[0052] The flow restriction members 1650 can be formed on the woven base by selectively
curing a photopolymeric resin on the woven base 1610. Such flow restriction members
1650 are generally liquid impermeable, such that second drainage zone has a second
drainage rate which is substantially zero. A suitable fiber retentive forming element
1600 can be formed with a photopolymeric resin as disclosed generally in U.S. Patent
5,503,715 issued April 2, 1996 in the name of Trokhan et al. and U.S. Patent 5,534,326
issued July 9, 1996 in the name of Trokhan et al, which patents are incorporated herein
by reference.
[0053] The flow restriction members 1650 can be formed of a combination of linear and/or
curvilinear segments 1660, which together form enclosed cells 1670. The segments 1660
have a width W (Figure 6) measured generally perpendicular to the segment's length.
If the web is formed of a single type of fiber, then the width W is preferably less
than about half, and more preferably less than about one fourth of the average fiber
length of the fibers. If the web is formed as a homogeneous mixture of different fiber
types including hardwood and softwood fibers, the segments 1660 have a width W which
is preferably less about half, and most preferably less than about one fourth of the
average fiber length of the hardwood fibers forming the web. On the other hand, if
the web comprises two or more layers, the width W should be less than about 1/2, and
more preferably less than about 1/4 the average fiber length of the hardwood fibers
in the layer adjacent to the forming element 1600.
[0054] For instance, for a furnish made up of 100 percent Eucalyptus fibers, the width W
should be less than about 0.5 millimeter, based on an average fiber length of about
1.0 mm. Alternatively, if the furnish is made up of 100 percent Northern Softwood
Kraft fibers having an average fiber length of about 3.0 mm, then the width W should
be less than about 1.5 mm.
[0055] The resulting decorative indicia can each comprise relatively low basis weight regions
having a closed path shape completely encircling at least one relatively higher basis
weight cell 240. The width of the relatively low basis weight regions (corresponding
to the width W) as measured at any point along the closed path shape is between about
0.2 millimeter and about 2 millimeter.
[0056] The flow restriction members 1650 can have any suitable decorative shape, including
but not limited to floral shapes, animal shapes, geometric shapes such as circles,
squares, and triangles, and the like. Preferably, the segments 1660 of the flow restriction
members 1650 are oriented on the forming element 1600 such that at least some of the
segments 1660, and preferably the majority of the segments 1660, form an included
angle A (Figure 6) of at least about 15 degrees with respect to the Cross Machine
Direction (CD in Figure 6) Such orientation provides the advantage that the relatively
low basis weight regions 220 are advantageously oriented with respect to the cross-machine
direction of the paper web. As the web is creped from the dryer drum, the doctor blade
is substantially parallel to the cross-machine direction of the paper web. As a result,
the doctor blade impact is less likely to adversely affect the appearance and structure
of the relatively low basis weight regions 220 if the segments 1660 are angled with
respect to the cross-machine direction. In particular, if the relatively low basis
weight regions are oriented to be substantially parallel to the cross-machine direction,
it is believed that the doctor blade can "pick out" portions of the relatively low
basis weight regions 220, thereby adversely affecting the decorative appearance of
the web.
[0057] It is anticipated that wood pulp in all its varieties will normally comprise the
paper making fibers used in this invention. However, other cellulose fibrous pulps,
such as cotton liners, bagasse, rayon, etc., can be used and none are disclaimed.
Wood pulps useful herein include chemical pulps such as Kraft, sulfite and sulfate
pulps as well as mechanical pulps including for example, ground wood, thermomechanical
pulps and Chemi-ThermoMechanical Pulp (CTMP). Pulps derived from both deciduous and
coniferous trees can be used. Alternatively, other non cellulosic fibers, such as
synthetic fibers, can be used.
[0058] Both hardwood pulps and softwood pulps, either separately or together may be employed.
The hardwood and softwood fibers can be blended, or alternatively, can be deposited
in layers to provide a stratified web. U.S. Patent 4, 300,981 issued Nov. 17, 1981
to Carstens and U.S. Patent 3,994,771 issued November 30, 1976 to Morgan et al. are
incorporated herein by reference for the purpose of disclosing layering of hardwood
and softwood fibers.
[0059] The paper furnish can comprise a variety of additives, including but not limited
to fiber binder materials, such as wet strength binder materials, dry strength binder
materials, and chemical softening compositions. Suitable wet strength binders include,
but are not limited to, materials such as polyamide-epichlorohydrin resins sold under
the trade name of KYMENE® 557H by Hercules Inc., Wilmington, Delaware. Suitable temporary
wet strength binders include but are not limited to synthetic polyacrylates. A suitable
temporary wet strength binder is PAREZ® 750 marketed by American Cyanamid of Stanford,
CT.
[0060] Suitable dry strength binders include materials such as carboxymethyl cellulose and
cationic polymers such as ACCO® 711. The CYPRO/ACCO family of dry strength materials
are available from CYTEC of Kalamazoo, MI.
[0061] The paper furnish deposited on the forming element 1600 can comprise a debonding
agent to inhibit formation of some fiber to fiber bonds as the web is dried. The debonding
agent, in combination with the energy provided to the web by the dry creping process,
results in a portion of the web being debulked. In one embodiment, the debonding agent
can be applied to fibers forming an intermediate fiber layer positioned between two
or more layers. The intermediate layer acts as a debonding layer between outer layers
of fibers. The creping energy can therefore debulk a portion of the web along the
debonding layer.
[0062] As a result, the web can be formed to have a relatively smooth surface for efficient
drying on a heated drying surface, such as the heated drying surface of a Yankee drying
drum. Yet, because of the rebulking at the creping blade, the dried web can also have
differential density regions, including a continuous network relatively high density
region, and discrete relatively low density regions which are created by the creping
process.
[0063] Suitable debonding agents include chemical softening compositions such as those disclosed
in U.S. Patent 5,279,767 issued January 18, 1994 to Phan et al. Suitable biodegradable
chemical softening compositions are disclosed in U.S. Patent 5,312,522 issued May
17, 1994 to Phan et al. U.S. Patents 5,279,767 and 5,312,522 are incorporated herein
by reference. Such chemical softening compositions can be used as debonding agents
for inhibiting fiber to fiber bonding in one or more layers of the fibers making up
the web.
[0064] One suitable softener for providing debonding of fibers in one or more layers of
fibers forming the web 20 is a papermaking additive comprising DiEster Di(Touch Hardened)
Tallow Dimethyl Ammonium Chloride. A suitable softener is ADOGEN® brand papermaking
additive available from Witco Company of Greenwich, CT.
[0065] The embryonic web 543 is preferably prepared from an aqueous dispersion of papermaking
fibers, though dispersions in liquids other than water can be used. The fibers are
dispersed in the carrier liquid to have a consistency of from about 0.1 to about 0.3
percent. The percent consistency of a dispersion, slurry, web, or other system is
defined as 100 times the quotient obtained when the weight of dry fiber in the system
under consideration is divided by the total weight of the system. Fiber weight is
always expressed on the basis of bone dry fibers.
[0066] The embryonic web 543 can be formed in a continuous papermaking process, as shown
in Figure 4, or alternatively, a batch process, such as a handsheet making process
can be used. After the dispersion of papermaking fibers is deposited onto the forming
element 1600, the embryonic web 543 is formed by removal of a portion of the aqueous
dispersing medium through the forming element 1600 by techniques well known to those
skilled in the art. Vacuum boxes, forming boards, hydrofoils, and the like are useful
in effecting water removal from the aqueous dispersion of papermaking fibers to form
embryonic web 543.
[0067] Figure 7 shows an embryonic web being formed on the forming element 1600. The portions
of the embryonic web supported on the flow restriction members 1650 are designated
543A, and the portions of the embryonic web supported on the woven base 1610 are designated
543B. The portions 543A correspond to the relatively low basis weight regions 220
in Figures 1A and 1B, and the portions 543B correspond to the relatively high basis
weight background 100 and the cells 240 in Figures 1A and 1B.
[0068] The difference in elevation D between the top surface of the flow restriction members
1650 and the woven base 1610 is preferably less than about 6 mils (0.006 inch; 0.152
millimeter) in order to provide an generally monoplanar embryonic web 543 having substantially
smooth first and second surfaces 547 and 549. More preferably, the difference in elevation
D is less than about 3 mils. Preferably, the elevation D is preferably less than about
1/6 the average fiber length of the fibers in the web, and most preferably less than
about 1/6 the average fiber length of the hardwood fibers in the web. The embryonic
web 543 travels with the forming element 1600 about a return roll 1502 and is brought
into the proximity of the web support apparatus 2200.
[0069] Referring to Figures 4, 8, 9, and 10, the next step in making the paper web 20 comprises
transferring the embryonic web 543 from the forming element 1600 to the web support
apparatus 2200, and supporting the transferred web (designated by numeral 545 in Figure
4) on the first side 2202 of the apparatus 2200. The embryonic web preferably has
a consistency of between about 5 and about 20 percent at the point of transfer to
the web support apparatus 2200.
[0070] Referring to Figures 8-10, the web support apparatus 2200 comprises a dewatering
felt layer 2220 and a web patterning layer 2250. The web support apparatus 2200 can
be in the form of a continuous belt for drying and imparting a pattern to a paper
web on a paper machine. The web support apparatus 2200 has a first web facing side
2202 and a second oppositely facing side 2204. The web support apparatus 2200 is viewed
with the first web facing side 2202 toward the viewer in Figures 8 and 9. The first
web facing side 2202 comprises a first web contacting surface and a second web contacting
surface.
[0071] In Figures 8 and 9, the first web contacting surface is a first felt surface 2230
of the felt layer 2220. The first felt surface 2230 disposed at a first elevation
2231. The first felt surface 2230 is a web contacting felt surface. The felt layer
2220 also has oppositely facing second felt surface 2232.
[0072] In Figures 8 and 9, the second web contacting surface is provided by the web patterning
layer 2250. The web patterning layer 2250, which is joined to the felt layer 2220,
has a web contacting top surface 2260 at a second elevation 2261. The difference between
the first elevation 2231 and the second elevation 2261 is less than the thickness
of the paper web when the paper web is transferred to the web support apparatus 2200.
The surfaces 2260 and 2230 can be disposed at the same elevation, so that the elevations
2231 and 2261 are the same. Alternatively, surface 2260 can be slightly above surface
2230, or surface 2230 can be slightly above surface 2260.
[0073] The difference in elevation is greater than or equal to 0.0 mils and less than about
8.0 mils. In one embodiment, the difference in elevation is less than about 6.0 mils
(0.15 mm), more preferably less than about 4.0 mils (0.10 mm), and most preferably
less than about 2.0 mil (0.05 mm), in order to maintain a relatively smooth surface
24.
[0074] The dewatering felt layer 2220 is water permeable and is capable of receiving and
containing water pressed from a wet web of papermaking fibers. The web patterning
layer 2250 is water impervious, and does not receive or contain water pressed from
a web of papermaking fibers. The web patterning layer 2250 can have a continuous web
contacting top surface 2260, as shown in Figures 8 and 9. Alternatively, the web patterning
layer can be discontinuous or semicontinuous.
[0075] The web patterning layer 2250 preferably comprises a photosensitive resin which can
be deposited on the first surface 2230 as a liquid and subsequently cured by radiation
so that a portion of the web patterning layer 2250 penetrates, and is thereby securely
bonded to, the first felt surface 2230. The web patterning layer 2250 preferably does
not extend through the entire thickness of the felt layer 2220, but instead extends
through less than about half the thickness of the felt layer 2220 to maintain the
flexibility and compressibility of the web support apparatus 2200, and particularly
the flexibility and compressibility of the felt layer 2220.
[0076] A suitable dewatering felt layer 2220 comprises a nonwoven bait 2240 of natural or
synthetic fibers joined, such as by needling, to a support structure formed of woven
filaments 2244. Suitable materials from which the nonwoven batt can be formed include
but are not limited to natural fibers such as wool and synthetic fibers such as polyester
and nylon. The fibers from which the batt 2240 is formed can have a denier of between
about 3 and about 20 grams per 9000 meters of filament length.
[0077] The felt layer 2220 can have a layered construction, and can comprise a mixture of
fiber types and sizes. The felt layer 2220 is formed to promote transport of water
received from the web away from the first felt surface 2230 and toward the second
felt surface 2232. The felt layer 2220 can have finer, relatively densely packed fibers
disposed adjacent the first felt surface 2230. The felt layer 2220 preferably has
a relatively high density and relatively small pore size adjacent the first felt surface
2230 as compared to the density and pore size of the felt layer 2220 adjacent the
second felt surface 2232, such that water entering the first surface 2230 is carried
away from the first surface 2230.
[0078] The dewatering felt layer 2220 can have a thickness greater than about 2 mm. In one
embodiment the dewaiering felt layer 2220 can have a thickness of between about 2
mm and about 5 mm.
[0079] PCT Publications WO 96/00812 published January 11, 1996, WO 96/25555 published August
22, 1996, WO 96/25547 published August 22, 1996, all in the name of Trokhan et al.;
U.S. Patent Application 08/701,600 "Method for Applying a Resin to a Substrate for
Use in Papermaking" filed August 22, 1996; U.S. Patent Application 08/640,452 "High
Absorbence/Low Reflectance Felts with a Pattern Layer" filed April 30, 1996; and U.S.
Patent Application 08/672,293 "Method of Making. Wet Pressed Tissue Paper with Felts
Having-Selected Permeabilities" filed June 28, 1996 are incorporated herein by reference
for the purpose of disclosing applying a photosensitive resin to a dewatering felt
and for the purpose of disclosing suitable dewatering felts.
[0080] The dewatering felt layer 2220 can have an air permeability of less than about 5.6
standard cubic meter per min (scmm) [200 standard cubic feet minute (scfm)], where
the air permeability in scmm (in scfm) is a measure of the number of cubic meter (cubic
feet) of air per minute that pass through a 926.03 cm
2 (one square foot) area of a felt layer, at a pressure differential across the dewatering
felt thickness of about 1.27 cm (about 0.5 inch) of water. In one embodiment, the
dewatering felt layer 2220 can have an air permeability of between about 0.14 scmm
and about 5.6 scmm (between about 5 and about 200 scfm), and more preferably less
than about 2.80 scmm (100 scfm).
[0081] The dewatering felt layer 2220 can have a basis weight of between about 800 and about
2000 grams per square meter, an average density (basis weight divided by thickness)
of between about 0.35 gram per cubic centimeter and about 0.45 gram per cubic centimeter.
The air permeability of the web support apparatus 2200 is less than or equal to the
permeability of the felt layer 2220.
[0082] One suitable felt layer 2220 is an Amflex 2 Press Felt manufactured by the Appleton
Mills Company of Appleton, Wisconsin. The felt layer 2220 can have a thickness of
about 3 millimeter, a basis weight of about 1400 gm/square meter, an air permeability
of about 0.84 scmm (30 scfm), and have a double layer support structure having a 3
ply multifilament top and bottom warp and a 4 ply cabled monofilament cross-machine
direction weave. The batt 2240 can comprise polyester fibers having a denier of about
3 at the first surface 2230, and a denier of between about 10-15 in the batt substrate
underlying the first surface 2230.
[0083] The web support apparatus 2200 shown in Figure 9 has a web patterning layer 2250
having a continuous network web contacting top surface 2260 having a plurality of
discrete openings 2270 therein. Suitable shapes for the openings 2270 include, but
are not limited to circles, ovals elongated in the machine direction (MD in Figure
9), polygons, irregular shapes, or mixtures of these. The projected surface area of
the continuous network top surface 2260 can be between about 5 and about 75 percent
of the projected area of the web support apparatus 2200 as viewed in Figure 9, and
is preferably between about 25 percent and about 50 percent of the projected area
of the apparatus 2200.
[0084] The continuous network top surface 2260 can have at least about 10,000, and more
preferably at least about 50,000 discrete openings 2270 per square meter of the projected
area of the apparatus 2200, and more preferably at least about 15,000 discrete openings
2270 per square meter of the apparatus 2200 as viewed in Figure 9. In one embodiment,
the continuous network top surface 2260 has at least about 100,000 discrete openings
2270 per square meter.
[0085] The discrete openings 2270 can be bilaterally staggered in the machine direction
(MD) and cross-machine direction (CD) as described in U.S. Patent 4,637,859 issued
January 20, 1987, which patent is incorporated herein by reference. Alternatively,
the other photopolymer patterns can be used for providing different patterns of densification
of the web.
[0086] The web is transferred to the web support apparatus 2200 such that the first face
547 of the transferred web 545 is supported on and conformed to the side 2202 of the
apparatus 2200, with parts of the web 545 supported on the surface 2260 and parts
of the web supported on the felt surface 2230. The second face 549 of the web is maintained
in a substantially smooth, macroscopically monqplanar configuration. Refertring to
Figure 10, the elevation difference between the surface 2260 and the surface 2230
of the web support apparatus 2200 is sufficiently small that the second face of the
web remains substantially smooth and macroscopically monoplanar when the web is transferred
to the apparatus 2200. In particular, the difference in elevation between the surface
2260 and the surface 2230 should be smaller than the thickness of the embryonic web
at the point of transfer.
[0087] The steps of transferring the embryonic web 543 to the apparatus 2200 can be provided,
at least in part, by applying a differential fluid pressure to the embryonic web 543.
Referring to Figure 4, the embryonic web 543 can be vacuum transferred from the forming
element 1600 to the apparatus 2200 by a vacuum source 600 depicted in Figure 4, such
as a vacuum shoe or a vacuum roll. One or more additional vacuum sources 620 can also
be provided downstream of the embryonic web transfer point to provide further dewatering.
[0088] The web 545 is carried on the apparatus 2200 in the machine direction (MD in Figure
4) to a nip 800 provided between a vacuum pressure roll 900 and a hard surface 875
of a heated Yankee dryer drum 880. Referring to Figure 11, a steam hood 2800 can be
positioned just upstream of the nip 800. The steam hood can be used to direct steam
onto the surface 549 of the web 545 as the surface 547 of the web 545 is carried over
the vacuum pressure roll 900.
[0089] The steam hood 2800 is mounted opposite a section of the vacuum providing portion
920 of the vacuum pressure roll. The vacuum providing portion 920 draws the steam
into the web 545 and the felt layer 2220. The steam provided by steam hood 2800 heats
the water in the paper web 545 and the felt layer 2220, thereby reducing the viscosity
of the water in the web and the felt layer 2220. Accordingly, the water in the web
and the felt layer 2220 can be more readily removed by the vacuum provided by roll
900.
[0090] The steam hood 2800 can provide about 136.08 g (0.3 pound) of saturated steam per
453.6 g (pound) of dry fiber at a pressure of less than about 103.42 kPa (15 psi).
The vacuum providing portion 920 provides a vacumm of between about 2.54 cm and about
38.10 cm (between about 1 and about 15 inches) of Mercury, and preferably between
about 7.62 cm and about 30.48 cm (between about 3 and about 12 inches) of Mercury
at the surface 2204.
[0091] A suitable vacuum pressure roll 900 is a suction pressure roll manufactured by Winchester
Roll Products. A suitable steam hood 2800 is a model D5A manufactured by Measurex-Devron
Company of North Vancouver, British Columbia, Canada.
[0092] The vacuum providing portion 920 is in communication with a source of vacuum (not
shown). The vacuum providing portion 920 is stationary relative to the rotating surface
910 of the roll 900. The surface 910 can be a drilled or grooved surface through which
vacuum is applied to the surface 2204. The surface 910 rotates in the direction shown
in Figure 11. The vacuum providing portion 920 provides a vacuum at the surface 2204
of the web support apparatus 2200 as the web and apparatus 2200 are carried through
the steam hood 2800 and through the nip 800. While a single vacuum providing portion
920 is shown, in other embodiments it may be desirable to provide separate vacuum
providing portions, each providing a different vacuum at the surface 2204 as the apparatus
2200 travel around the roll 900.
[0093] The Yankee dryer typically comprises a steam heated steel or iron drum. Referring
to Figure 11, the web 545 is carried into the nip 800 supported on the apparatus 2200,
such that the substantially smooth second face 549 of the web can be transferred to
the surface 875. Upstream of the nip, prior to the point where the web is transferred
to the surface 875, a nozzle 890 applies an adhesive to the surface 875.
[0094] The adhesive can be a polyvinyl alchohol based adhesive. Alternatively, the adhesive
can be CREPTROL® brand adhesive manufactured by Hercules Company of Wilmington Delaware.
Other adhesives can also be used. Generally, for embodiments where the web is transferred
to the Yankee drum 880 at a consistency greater than about 45 percent, a polyvinyl
alchohol based creping adhesive can be used. At consistencies lower than about 40
percent, an adhesive such as the CREPTROL® adhesive can be used.
[0095] The adhesive can be applied to the web directly, or indirectly (such as by application
to the Yankee surface 875), in a number of ways. For instance, the adhesive can be
sprayed in micro-droplet form onto the web, or onto the Yankee surface 875. Alternatively,
the adhesive could also be applied to the surface 875 by a transfer roller or brush.
In yet another embodiment, the creping adhesive could be added to the paper furnish
at the wet end of the papermachine, such as by adding the adhesive to the paper furnish
in the headbox 500. From about 0.91 kg to about 1.81 kg (about 2 pounds to about 4
pounds) of adhesive can be applied per ton of paper fibers dried on the Yankee drum
880.
[0096] As the web is carried on the apparatus 2200 through the nip 800, the vacuum providing
portion 920 of the roll 900 provides a vacuum at the surface 2204 of the web support
apparatus 2200. Also, as the web is carried on the apparatus 2200 through the nip
800, between the vaccuum pressure roll 900 and the dryer surface 800, the web patterning
layer 2250 of the web support apparatus 2200 imparts the pattern corresponding to
the surface 2260 to the first face 547 of the web 545. Because the second face 549
is a substantially smooth, macroscopically monoplanar face, substantially all of the
of the second surface 549 is positioned against, and adhered to, the dryer surface
875 as the web is carried through the nip 800. As the web is carried through the nip,
the second face 549 is supported against the smooth surface 875 to be maintained in
a substantially smooth, macroscopically monoplanar configuration. Accordingly, a predetermined
pattern can be imparted to the first face 547 of the web 545, while the second face
549 remains substantially smooth. The web 545 preferably has a consistency of between
about 20 percent and about 60 percent when the web 545 is transferred to the surface
875 and the pattern of surface 2260 is imparted to the web to selectively density
the web. The pattern of the surface 2260 is imparted to the web to provide the continuous
network region 110 and the discrete, relatively low density regions 130 shown in Figure
1A and Figure 1B.
[0097] Without being limited by theory, it is believed that, as a result of having substantially
all of the second face 549 positioned against the Yankee surface 875, drying of the
web 545 on the Yankee is more efficient than would be possible with a web which has
only selective portions of the second face against the Yankee.
[0098] In particular, it is believed that positioning substantially all of the second face
549 against the Yankee permits a web 545 having a basis weight of at least about 8
pounds per 3000 square feet (13 grams/square meter), and more preferably at least
about 10 pounds per 3000 square feet (16.3 grams/square meter) to be dried from a
relatively low consistency to a relatively high consistency on the Yankee drum at
a relatively high Yankee drum speed. Further, it is believed such a web 545 having
the above basis weight characteristics can be dried from a consistency of less than
about 30 percent and more preferably less than about 25 percent (when the web is transferred
to the drum 880), to a consistency of at least about 90 percent, and more preferably
at least about 95 percent (when the web is removed from the drum by creping) at a
relatively high web speed which permits economical production of the paper web 20.
[0099] In comparison, it is believed that for the same drying conditions and dryer design,
the Yankee dryer speed for drying paper having a continuous network and discrete domes
as disclosed in U.S. Patent 4,637,859 and a basis weight of at least about 16.4 g
per square meter (about 10 pounds per 3000 square feet) can be limited due to the
tendency of the domes to not dry as rapidly as the continuous network.
[0100] The final step in forming the paper structure 20 comprises creping the web 545 from
the surface 875 with a doctor blade 1000, as shown in Figure 4. Without being limited
by theory, it is believed that the energy imparted by the doctor blade 1000 to the
web 545 bulks, or de-densifies, at least some portions of the web, especially those
portions of the web which are not imprinted by the web patterning surface 2260, such
as relatively low density regions 130 and 280. Accordingly, the step of creping the
web from the surface 875 with the doctor blade 1000 provides a web having a first,
compacted, relatively thinner region corresponding to the pattern imparted to the
first face of the web, and a second relatively thicker region. In one embodiment,
the doctor blade has a bevel angle of about 25 degrees and is positioned with respect
to the Yankee dryer to provide an impact angle of about 81 degrees.
[0101] The paper structure 20 shown in Figure 1B and 3 exhibits forshortening due to creping
in both the relatively high density, continuous network region 110 and the relatively
low density, discrete regions 130. The creping frequency in the region 110 can be
different than the creping frequency in the regions 130. Generally, the creping frequency
in the regions 130 is lower than the creping frequency in the continuous network 110.
This difference in crepe frequency is illustrated in Figure 1B, where the crepe ridges
115 are more closely spaced together (higher frequency) than are the crepe ridges
135.
[0102] Accordingly, the paper web 20 provides decorative aesthetics imparted by the decorative
indicia 200 without the need for embossing. Further, the web 20 exhibits flexibility
provided by creping in both high and low density regions, bulk and absorbency provided
by the low density regions 130 and 280, and softness provided by the relatively smooth
surface 24.
[0103] In another alternative embodiment of the present invention, the web support apparatus
2200 can comprise a resin layer disposed on a foraminous background element comprising
a fabric of woven filaments. Referring to Figures 14-18, the apparatus 2200 can comprise
a resin layer 2250 disposed on a woven fabric 1220. The resin layer 2250 has a continuous
network web contacting surface 2260 defining discrete openings 2270, as shown in Figure
14. The woven fabric 1220 comprises machine direction filaments 1242 and cross machine
direction filaments 1241. The apparatus 2200 has a first side 2202 and a second side
2204. The first side 2202 includes first and second web contacting surfaces.
[0104] In Figure 14 and 15, the first web contacting surface at a first elevation 1231 is
provided by discrete knuckle surfaces 1230 located at cross-over points of the filaments
1241 and 1242. The top surfaces of the filaments 1241 and 1242 can be sanded or otherwise
ground to provide relatively flat, generally oval shaped knuckle surfaces 1230. The
second web contacting surface is provided by the web patterning layer 2250. The web
patterning layer 2250, which is joined to the woven fabric 1220, has a web contacting
top surface 2260 at a second elevation 2261.
[0105] The difference between the first elevation 1231 and the second elevation 2261 is
less than the thickness of the paper web when the paper web is transferred to the
web support apparatus 2200. The continuous surface 2260 and the discrete surfaces
1230 can be disposed at the same elevation, so that the elevations 1231 and 2261 are
the same. Alternatively, surface 2260 can be slightly above the surfaces 1230, or
surfaces 1230 can be slightly above surface 2260.
[0106] The difference in elevation is greater than or equal to 0.0 mils and less than about
5.0 mils. In one embodiment, the difference in elevation is less than about 4.0 mils
(0.10 mm), more preferably less than about 2.0 mils (0.05 mm), and most preferably
less than about 1.0 mil (0.025 mm), in order to maintain a relatively smooth surface
24 of the dried web.
[0107] The web support apparatus 2200 shown in Figures 14 and 15 can be used to form the
paper web shown in Figures 12 and 13. Figure 12 is a plan view illustration of a paper
web 20 according to an alternative embodiment of the present invention. Figure 13
is a cross-sectional illustration of a paper web of the type illustrated in Figure
12.
[0108] Referring to Figures 12 and 13, the paper web 20 has a background portion 100 and
decorative indicia 200 comprising relatively low basis weight regions 220. The background
portion 100 comprises a relatively high density continuous network 110, and discrete,
relatively lower density regions 130 dispersed throughout the continuous network region
110. One or more discrete, relatively high density region 135 is dispersed throughout
each of the relatively lower density regions 130.
[0109] The relatively low basis weight regions 220 can have a closed path shape outlining
a plurality of adjacent, relatively higher basis weight cells 240 (seven cells 240
in Figure 12). The basis weight everywhere within each of the cells 240 is higher
than the basis weight of the regions 220 encircling the particular cell 240. Each
cell 240 has a perimeter formed by a closed loop portion of the relatively low basis
weight regions 220. The cells 240 can be selectively densified to comprise a relatively
high density, continuous network 260 and discrete, relatively low density regions
280 dispersed throughout the continuous network 260. Each discrete relatively low
density region 280 encircles a plurality of discrete, relatively higher density regions
285.
[0110] The continuous networks 110 and 260 and correspond to the surface 2260 of the web
support apparatus 2200 shown in Figure 14. The discrete, relatively high density regions
135 and 285 correspond to the surfaces 1230 shown in Figure 14. The relatively lower
density regions 130 and 280 of the web in Figure 12 correspond to those portions of
the web which are not registered with either the surface 2260 or the surfaces 1230.
[0111] Figure 13 is a cross-sectional view of a portion of a paper web of the type shown
in Figure 12. The line density through the web thickness in Figure 13 is used to schematically
illustrate the relative basis weights of different portions of the web. The portions
of the web illustrated with 5 lines through the web thickness represent relatively
high basis weight regions, and the portions of the web illustrated with 3 lines represent
relatively low basis weight regions.
[0112] Figures 16-18 illustrate formation of a web 20 of the type shown in Figure 12 using
the web support apparatus 2200. As described above with respect to Figures 4-7, an
embryonic web 543 having first and second smooth surfaces is formed on a forming element
1600 to have relatively low basis weight decorative indicia and a relatively high
basis weight background. The web is then vacuum transferred to the apparatus 2200,
to provide a web 545 supported on the first side 2202 of the apparatus 2200. As shown
in Figure 17, the first surface 547 is conformed to the surface 2260 and the surfaces
1230, and the second surface 549 is maintained as a substantially smooth, macroscopically
monoplanar surface.
[0113] The web 545 and web support apparatus 2200 are next carried through a through air
drying apparatus 650 (Figure 16), wherein heated air is directed through the web 545
while the web 545 is supported on the apparatus 2200. The heated air is directed to
enter the surface 549 and to pass through the web 545 and then through the apparatus
2200.
[0114] The through air drying apparatus 650 can be used to dry the web 545 to a consistency
of from about 30 percent to about 70 percent. U.S. Patent 3,303,576 to Sisson and
U.S. patents 5,274,930 and 5,584,126 issued to Ensign et al. are incorporated herein
by reference for the purpose of showing suitable through air dryers for use in the
practice of the present invention. Alternatively, the web can be dewatered according
to the teachings of U.S. Patent 4,556,450 issued December 3, 1985 to Chuang et al.
which patent is incorporated herein by reference.
[0115] The partially dried web 545 and the apparatus 2200 are directed to pass through a
nip 800 formed between a pressure roll 900 and a Yankee drum 880. The continuous network
surface 2260 and the discrete surfaces 1230 are impressed into the surface 547 of
the web 545 as the web is carried through the nip 800. An adhesive supplied by nozzle
890 is used to adhere substantially all of the substantially smooth surface 549 to
the surface 875 of the heated Yankee drum 880.
[0116] While a single forming element 1600 is shown in Figures 4 and 16, it will be understood
that other forming wire configurations can be used in combination with one or more
headboxes, each headbox having a capability of providing one or more layers of fiber
furnish, in order to provide a multiple layer web. U.S. Patent 3,994,771 issued to
Morgan et al. and U.S. Patent 4,300,981 issued to Carstens et al. and commonly assigned
U.S. Patent Application "Layered Tissue Having Improved Functional Properties" filed
October 24, 1996 in the names of Phan and Trokhan disclose layering and are incorporated
by reference herein. Various types of forming wire configurations, including twin
wire formers can be used. Additionally, various types of headbox designs can be employed
to provide a web having one or more fiber layers.
[0117] In yet another embodiment, the web supported on a web support apparatus 2200 can
be dewatered by pressing the web between the support apparatus, such as the type shown
in Figures 9 or 14, and a dewatering felt layer in a press nip. The web is positioned
between the web support apparatus 2200 and the dewatering felt layer in the press
nip. The following patent documents are incorporated herein by reference for the purpose
of illustrating dewatering of a web by pressing the web:
PCT Publications WO 96/00812 published January 11, 1996, WO 96/25555 published August
22, 1996, WO 96/25547 published August 22, 1996, all in the name of Trokhan et al.;
U.S. Patent Application 08/701,600 "Method for Applying a Resin to a Substrate for
Use in Papermaking" filed August 22, 1996; U.S. Patent Application 08/640,452 "High
Absorbence/Low Reflectance Felts with a Pattern Layer" filed April 30, 1996; and U.S.
Patent Application 08/672,293 "Method of Making Wet Pressed Tissue Paper with Felts
Having Selected Permeabilities" filed June 28, 1996; and U.S. Patent 5,580,423 issued
December 3, 1996 to Ampulski et al.
Examples:
[0118] The following examples illustrate the practice of the present invention but are not
intended to be limiting thereof.
EXAMPLE 1
[0119] First, a 3% by weight aqueous slurry of Northern Softwood Kraft (NSK) fibers is made
using a conventional re-pulper. A 2% solution of the temporary wet strength resin
(i.e., PAREZ® 750 marketed by American Cyanamid corporation of Stanford, CT) is added
to the NSK stock pipe at a rate of 0.2% by weight of the dry fibers. The NSK slurry
is diluted to about 0.2% consistency at the fan pump. Second, a 3% by weight aqueous
slurry of Eucalyptus fibers is made up using a conventional repulper. A 2% solution
of the debonder (i.e., Adogen® SDMC marketed by Witco Corporation of Dublin, OH) is
added to one of the Eucalyptus stock pipe at a rate of 0.1% by weight of the dry fibers.
The Eucalyptus slurry is diluted to about 0.2% consistency at the fan pump.
[0120] The treated furnish streams are mixed in the headbox and deposited onto a forming
element 1600 of the type shown in Figure 6 to form a homogenous web. The forming element
1600 comprises a Fourdrinier forming wire having flow restriction members 1650 formed
by a photopolymer layer cured on the forming wire. Dewatering occurs through the forming
wire and is assisted by a deflector and vacuum boxes. The forming wire, manufactured'
by Appleton Wire of Appleton, Wisconsin, is a triple-layer square weave configuration
having 90 machine-direction and 72 cross-machine-direction monofilaments per 2.54
cm (per inch), respectively. The monofilament diameter ranges from about 0.15 mm to
about 0.20 mm. The forming wire air permeability is about 29.40 scmm (about 1050 scfm).
Flow through the forming wire is impeded by photopolymer flow restriction members
1650 having a flower-like shape, as shown in Figure 5. The flow restriction members
1650, combined, have a projected area equal to about 10 percent of the projected area
of the forming element. The difference in elevation D (Figure 7) is about 0.003 inch
(0.076 millimeter).
[0121] The embryonic wet web is transferred from the forming element 1600, at a fiber consistency
of about 10% at the point of transfer, to a web support apparatus 2200 having a dewatering
felt layer 2220 and a photosensitive resin web patterning layer 2250. The dewatering
felt 2220 is a Amflex 2 Press Felt. The felt 2220 comprises a batt of polyester fibers.
The ban has a surface denier of 3, a substrate denier of 10-15. The felt layer 2220
has a basis weight of 1436 gm/square meter, a caliper of about 3 millimeter, and an
air permeability of about 0.84 scmm to about 1.12 scmm (about 30 to about 40 scfm).
The web patterning layer 2250 comprises a continuous network web contacting surface
2260 defining a plurality of discrete openings 2270 which are elongated in the machine
direction (MD), as shown in Figure 9. The web patterning layer 2250 has a projected
area equal to about 35 percent of the projected area of the web support apparatus
2200. The difference in elevation 2261 between the top web contacting surface 2260
and the first felt surface 2230 is about 0.005 inch (0.127 millimeter),
[0122] The embryonic web is transferred to the web support apparatus 2200 to provide a generally
monoplanar web 545. Transfer and deflection are provided at the vacuum transfer point
with a pressure differential of about 50.80 cm (20 inches) of mercury. Further de-watering
is accomplished by vacuum assisted drainage until the web has a fiber consistency
of about 25%. The web 545 is carried to the nip 800. The vacuum roll 900 has a compression
surface 910 having a hardness of about 60 P&J. The web 545 is compacted against the
compaction surface 875 of the Yankee dryer drum 880 by pressing the web 545 and the
web support apparatus 200 between the compression surface 910 and the Yankee dryer
drum 880 surface at a compression pressure of about 1378.94 kPa (about 200 psi). A
polyvinyl alcohol based creping adhesive is used to adhere the compacted web to the
Yankee dryer. The fiber consistency is increased to at least about 90% before dry
creping the web with a doctor blade. The doctor blade has a bevel angle of about 20
degrees and is positioned with respect to the Yankee dryer to provide an impact angle
of about 76 degrees; the Yankee dryer is operated at about 800 fpm (feet per minute)
(about 244 meters per minute). The dry web is formed into roll at a speed of 650 fpm
(200 meters per minutes).
[0123] The decorative web is converted into a two-ply bath tissue paper. The two-ply toilet
tissue paper has a basis weight of about 40.98 g per square meter (about 25 pounds
per 3000 square feet), and contains about 0.2% of the temporary wet strength resin
and about 0.1% of the debonder. The resulting two-ply tissue paper is bulky; soft,
absorbent, aesthetic and is suitable for use as bath tissues.
EXAMPLE 2
[0124] First, a 3% by weight aqueous slurry of Northern Softwood Kraft (NSK) fibers is made
using a conventional re-pulper. A 2% solution of the temporary wet strength resin
(i.e., PAREZ® 750 marketed by American Cyanamid corporation of Stanford, CT) is added
to the NSK stock pipe at a rate of 02% by weight of the dry fibers. The NSK slurry
is diluted to about 0.2% consistency at the fan pump. Second, a 3% by weight aqueous
slurry of Eucalyptus fibers is made up using a conventional re-pulper. A 2% solution
of the debonder (i.e., Adogen® SDMC marketed by Witco Corporation of Dublin. OH) is
added to one of the Eucalyptus stock pipe at a rate of 0.5% by weight of the dry fibers.
The Eucalyptus slurry is diluted to about 0.2% consistency at the fan pump. Third,
a 3% by weight aqueous slurry of Eucalyptus fibers is made up using a conventional
re-pulper. A 2% solution of the debonder (i.e., Adogen® SDMC marketed by Witco Corporation
of Dublin, OH) and a 2% solution of dry strength binder (i.e., Redibond® 5320 marketed
by National Starch and Chemical corporation of New York, New York) are added to the
Eucalyptus stock pipe at a rate of 0.1% by weight of the dry fibers. The Eucalyptus
slurry is diluted to about 0.2% consistency at the fan pump.
[0125] The individual treated furnish streams (stream 1 = 100% NSK / stream 2 = 100% debonded
Eucalyptus / stream 3 = 100% Eucalyptus) are separated in the headbox and deposited
onto a forming element 1600 of the type shown in Figure 6 to form a 3-layer web. The
forming element 1600 comprises a forming wire. Dewatering occurs through the forming
wire and is assisted by a deflector and vacuum boxes. The forming wire, manufactured
by Appleton Wire of Appleton, Wisconsin, is a triple-layer square weave configuration
having 90 machine-direction and 72 cross-machine-direction monofilaments per 2.54
cm (per inch), respectively. The monofilament diameter ranges from about 0.15 mm to
about 0.20 mm. The forming wire air permeability is about 29.4 scmm (1050 scfm). Flow
through the forming wire is impeded with photopolymer flow restriction members 1650
having a flower-like shape, as shown in Figure 6. The flow restriction members 1650,
combined, have a projected area equal to about 10 percent of the projected area of
the forming element 1600. The difference in elevation D (Figure 7) is about 0.003
inch (0.076 millimeter).
[0126] The embryonic wet web is transferred from the forming element 1600, at a fiber consistency
of about 10% at the point of transfer, to a web support apparatus 2200 having a dewatering
felt layer 2220 and a photosensitive resin web patterning layer 2250. The dewatering
felt 2220 is a Amflex 2 Press Felt. The felt 2220 comprises a batt of polyester fibers.
The batt has a surface denier of 3, a substrate denier of 10-15. The felt layer 2220
has a basis weight of 1436 gm/square meter, a caliper of about 3 millimeter, and an
air permeability of about 0.84 to about 1.12 scmm (about 30 to about 40 scfm). The
web patterning layer 2250 comprises a continuous web contacting surface 2260 defining
discrete openings 2270, as shown in Figure 9. The web patterning layer 2250 has a
projected area equal to about 35 percent of the projected area of the web support
apparatus 2200. The difference in elevation 2261 between the top web contacting surface
2260 and the first felt surface 2230 is about 0.010 inch (0.254 millimeter).
[0127] The embryonic web is transferred to the web support apparatus 2200 to provide a generally
monoplanar web 545. Transfer and deflection are provided at the vacuum transfer point
with a pressure differential of about 50.80 cm (about 20 inches) of mercury. Further
de-watering is accomplished by vacuum assisted drainage until the web has a fiber
consistency of about 25%. The web 545 is carried to the nip 800. The vacuum roll 900
has a compression surface 910 having a hardness of about 60 P&J. The web 545 is compacted
against the compaction surface 875 of the Yankee dryer drum 880 by pressing the web
545 and the web support apparatus 200 between the compression surface 910 and the
Yankee dryer drum 880 surface at a compression pressure of about 1378.94 kPa (about
200 psi). A polyvinyl alcohol based creping adhesive is used to adhere the compacted
web to the Yankee dryer. The fiber consistency is increased to at least about 90%
before dry creping the web with a doctor blade. The doctor blade has a bevel angle
of about 20 degrees and is positioned with respect to the Yankee dryer to provide
an impact angle of about 76 degrees; the Yankee dryer is operated at about 800 fpm
(feet per minute) (about 244 meters per minute). The dry web is formed into roll at
a speed of 650 fpm (200 meters per minutes).
[0128] The decorative web is convened into a two-ply bath tissue paper. The two-ply bath
tissue paper has a basis weight of about 40.98 g per square meter (about pounds per
3000 square feet), and contains about 0.2% of the temporary wet strength resin and
about 0.1% of the debonder. The resulting two-ply tissue paper is bulky, soft, absorbent,
aesthetic and is suitable for use as bath tissues.
EXAMPLE 3
[0129] First, a 3% by weight aqueous slurry of Northern Softwood Kraft (NSK) fibers is made
using a conventional re-pulper. A 1% solution of the permanent wet strength resin
(i.e. Kymene® 557H marketed by Hercules Incorporated of Wilmington, DE) is added to
the furnish stock pipe at a rate of 0.25% by weight of the total sheet dry fibers.
A 0.25% solution of the dry strength resin (i.e., CMC from Hercules Incorporated of
Wilmington, DE) is added to the furnish stock before the fan pump at a rate of 0.05%
by weight of the total sheet dry fibers. Second, a 3% by weight aqueous slurry of
Eucalyptus fibers is made up using a conventional repulper. A 2% solution of the debonder
(i.e., Adogen® SDMC marketed by Witco Corporation of Dublin, OH) is added to one of
the Eucalyptus stock pipe at a rate of 0.1% by weight of the dry fibers. The Eucalyptus
slurry is diluted to about 0.2% consistency at the fan pump.
[0130] The individual treated furnish streams (stream 1 = 100% NSK / stream 2 = 100% Eucalyptus)
are separated in the headbox and deposited onto a forming element 1600 of the type
shown in Figure 6 to form a layered web. The forming element includes a forming wire.
Dewatering occurs through the forming wire and is assisted by a deflector and vacuum
boxes. The forming wire, manufactured by Appleton Wire of Appleton, Wisconsin, is
a triple-layer square weave configuration having 90 machine-direction and 72 cross-machine-direction
monofilaments per inch, respectively. The monofilament diameter ranges from about
0.15 mm to about 0.20 mm. The forming wire air permeability is about 29.40 scmm (1050
scfm). Flow through the forming wire is impeded with photopolymer flow restriction
members 1650 having a flower-like shape, as shown in Figure 6. The flow restriction
members 1650, combined, have a projected area equal to about 10 percent of the projected
area of the forming element 1600. The difference in elevation D (Figure 7) is about
0.003 inch (0.076 millimeter).
[0131] The embryonic wet web is transferred from the photo-polymer forming wire, at a fiber
consistency of about 10% at the point of transfer, to a web support-apparatus 2200
having a dewatering felt layer 2220 and a photosensitive resin web patterning layer
2250. The dewatering felt 2220 is a Amflex 2 Press Felt. The felt 2220 comprises a
batt of polyester fibers. The batt has a surface denier of 3, a substrate denier of
10-15. The felt layer 2220 has a basis weight of 1436 gm/square meter, a caliper of
about 3 millimeter, and an air permeability of about 0.84 to about 1.12 scmm (about
30 to about 40 scfm). The web patterning layer 2250 comprises a continuous network
web contacting surface 2260 defining discrete openings 2270, as shown in Figure 9.
The web patterning layer 2250 has a projected area equal to about 35 percent of the
projected area of the web support apparatus 2200. The difference in elevation 2261
between the top web contacting surface 2260 and the first felt surface 2230 is about
0.010 inch (0.254 millimeter).
[0132] The embryonic web is transferred to the web support apparatus 2200. Transfer and
deflection are provided at the vacuum transfer point with a pressure differential
of about 20 inches of mercury. Further de-watering is accomplished by vacuum assisted
drainage, and optionally, by pressing the web between the web support apparatus and
a separate dewatering felt. After pressing, the web is carried to the nip 800. The
vacuum roll 900 has a compression surface 910 having a hardness of about 60 P&J. The
web 545 is compacted against the compaction surface 875 of the Yankee dryer drum 880
by pressing the web 545 and the web support apparatus 200 between the compression
surface 910 and the Yankee dryer drum 880 surface at a compression pressure of about
1378.94 kPa (about 200 psi). A polyvinyl alcohol based creping adhesive is used to
adhere the compacted web to the Yankee dryer. The fiber consistency is increased to
at least about 90% before dry creping the web with a doctor blade. The doctor blade
has a bevel angle of about 25 degrees and is positioned with respect to the Yankee
dryer to provide an impact angle of about 81 degrees; the Yankee dryer is operated
at about 800 fpm (feet per minute) (about 244 meters per minute). The dry web is formed
into roll at a speed of 650 fpm (200 meters per minutes).
[0133] The decorative web is converted into a two-ply facial tissue paper. The two-ply facial
tissue paper has a basis weight of about 29.51 g per square meter (about 18 pounds
per 3000 square feet), contains about 1% of the permanent wet strength resin, about
0.2% of the dry strength binder and about 0.1% of the debonder. The resulting two-ply
tissue paper is bulky, soft, absorbent, aesthetic and is suitable for use as facial
tissues.
PROPHETIC EXAMPLES:
[0134] The following prophetic examples provide non-limiting illustrations of the practice
of the present invention.
EXAMPLE 4
[0135] First, a 3% by weight aqueous slurry of Northern Softwood Kraft (NSK) fibers is made
using a conventional re-pulper. A 2% solution of the temporary wet strength resin
(i.e., PAREZ® 750 marketed by American Cyanamid corporation of Stanford, CT) is added
to the NSK stock pipe at a rate of 0.2% by weight of the dry fibers. The NSK slurry
is diluted to about 0.2% consistency at the fan pump. Second, a 3% by weight aqueous
slurry of Eucalyptus fibers is made up using a conventional re-pulper. A 2% solution
of the debonder (i.e., Adogen® SDMC marketed by Witco Corporation of Dublin, OH) is
added to one of the Eucalyptus stock pipe at a rate of 0.1% by weight of the dry fibers.
The Eucalyptus slurry is diluted to about 0.2% consistency at the fan pump.
[0136] The treated furnish streams are mixed in the headbox and deposited onto a forming
element 1600 of the type shown in Figure 6 to form a homogeneous web. The forming
element includes a forming wire. Dewatering occurs through the forming wire and is
assisted by a deflector and vacuum boxes. The forming wire, manufactured by Appleton
Wire of Appleton, Wisconsin, is. a triple-layer square weave configuration having
90 machine-direction and 72 cross-machine-direction monofilaments per 2.54 cm (per
inch), respectively. The monofilament diameter ranges from about 0.15 mm to about
0.20 mm. The forming wire air permeability is about 29.40 scmm (1050 scfm). The forming
wire is impeded with photo-polymer flow restriction member 1650 having a flower-like
shape, as shown in Figure 6. The flow restriction members 1650, combined, have a projected
area equal to about 10 percent of the projected area of the forming element 1600.
The difference in elevation D (Figure 7) is about 0.003 inch (0.076 millimeter).
[0137] The embryonic wet web is transferred from the forming element 1600, at a fiber consistency
of about 10% at the point of transfer, to a web support apparatus 2200 of the type
shown in Figures 14-15 made in accordance with U.S. Patent No. 4,528,239, Trokhan,
issued on 9 July 1985, which patent is incorporated herein by reference. The difference
in elevation between the elevations 2261 and 1231 (Figure 15) is about 0.015 inch
(0.38 millimeter). Further de-watering is accomplished by vacuum assisted drainage
until the web has a fiber consistency of about 28%. The patterned web is pre-dried
by air blow-through to a fiber consistency of about 65% by weight. The web is then
adhered to the surface of a Yankee diyer with a sprayed creping adhesive comprising
0.25% aqueous solution of Polyvinyl Alcohol (PVA).
[0138] The fiber consistency is increased to at least about 90% before dry creping the web
with a doctor blade. The doctor blade has a bevel angle of about 25 degrees and is
positioned with respect to the Yankee dryer to provide an impact angle of about 81
degrees; the Yankee dryer is operated at about 800 fpm (feet per minute) (about 244
meters per minute). The dry web is formed into roll at a speed of 650 fpm (200 meters
per minutes).
[0139] The decorative web is converted into a two-ply bath tissue paper. The two-ply toilet
tissue paper has a basis weight of about 409.84 g per square meter (about 25 pounds
per 3000 square feet), and contains about 0.2% of the temporary wet strength resin
and about 0.1% of the debonder. The resulting two-ply tissue paper is bulky, soft,
absorbent, aesthetic and is suitable for use as bath tissues.
EXAMPLE 5
[0140] First, a 3% by weight aqueous slurry of Northern Softwood Kraft (NSK) fibers is made
using a conventional re-pulper. A 2% solution of the temporary wet strength resin
(i.e., PAREZ® 750 marketed by American Cyanamid corporation of Stanford, CT) is added
to the NSK stock pipe at a rate of 0.2% by weight of the dry fibers. The NSK slurry
is diluted to about 0.2% consistency at the fan pump. Second, a 3% by weight aqueous
slurry of Eucalyptus fibers is made up using a conventional re-pulper. A 2% solution
of the debonder (i.e., Adogen® SDMC marketed by Witco Corporation of Dublin, OH) is
added to one of the Eucalyptus stock pipe at a rate of 0.1% by weight of the dry fibers.
The Eucalyptus slurry is diluted to about 0.2% consistency at the fan pump.
[0141] The individual treated furnish streams (stream 1 = 100% Eucalyptus / stream 2 = 100%
NSK / stream 3 = 100% Eucalyptus) are separated in the headbox and deposited onto
a forming element 1600 of the type shown in Figure 6 to form a 3 layer web. The forming
element includes a forming wire. Dewatering occurs through the forming wire and is
assisted by a deflector and vacuum boxes. The forming wire, manufactured by Appleton
Wire of Appleton, Wisconsin, is a triple-layer square weave configuration having 90
machine-direction and 72 cross-machine-direction monofilaments per 2.54 cm (per inch).
respectively. The monofilament diameter ranges from about 0.15 mm to about 0.20 mm.
The forming wire air permeability is about 29.40 scmm (1050 scfm). Flow through the
forming wire is impeded with photo-polymer flow restriction member 1650 having a flower-like
shape, as shown in Figure 6. The flow restriction members 1650, combined, have a projected
area equal to about 10 percent of the projected area of the forming element 1600.
The difference in elevation D (Figure 7) is about 0.003 inch (0.076 millimeter).
[0142] The embryonic wet web is transferred from the forming element 1600 at a fiber consistency
of about 10% at the point of transfer, to a 44x33 drying/imprinting fabric of the
type shown in U.S. Patent 4,191,609 issued to Trokhan on March 4, 1980, incorporated
herein by reference. Further de-watering is accomplished by vacuum assisted drainage
until the web has a fiber consistency of about 28%. The patterned web is pre-dried
by air blow-through to a fiber consistency of about 65% by weight. The web is then
adhered to the surface of a Yankee dryer with a sprayed creping adhesive comprising
0.25% aqueous solution of Polyvinyl Alcohol (PVA).
[0143] The fiber consistency is increased to at least about 90% before dry creping the web
with a doctor blade. The doctor blade has a bevel angle of about 25 degrees and is
positioned with respect to the Yankee dryer to provide an impact angle of about 81
degrees; the Yankee dryer is operated at about 800 fpm (feet per minute) (about 244
meters per minute). The dry web is formed into roll at a speed of 650 fpm (200 meters
per minutes).
[0144] The decorative web is converted into a single-ply bath tissue paper. The single-ply
toilet tissue paper has a basis weight of about 29.51 g per square meter (about 18
pounds per 3000 square feet), and contains about 0.3% of the temporary wet strength
resin and about 0.1% of the debonder. The resulting single-ply tissue paper is bulky,
soft, absorbent, aesthetic and is suitable for use as bath tissues.
EXAMPLE 6
[0145] First, a 3% by weight aqueous slurry of Northern Softwood Kraft (NSK) fibers is made
using a conventional re-pulper. A 2% solution of the temporary wet strength resin
(i.e., PAREZ® 750 marketed by American Cyanamid corporation of Stanford, CT) is added
to the NSK stock pipe at a rate of 0.2% by weight of the dry fibers. The NSK slurry
is diluted to about 0.2% consistency at the fan pump. Second, a 3% by weight aqueous
slurry of Eucalyptus fibers is made up using a conventional re-pulper. A 2% solution
of the debonder (i.e., Adogen® SDMC marketed by Witco Corporation of Dublin, OH) is
added to one of the Eucalyptus stock pipe at a rate of 0.1% by weight of the dry fibers.
The Eucalyptus slurry is diluted to about 0.2% consistency at the fan pump.
[0146] The individual treated furnish streams (stream I = 100% Eucalyptus / stream 2 = 100%
NSK / stream 3 = 100% Eucalyptus) are separated in the headbox and deposited onto
a forming element 1600 of the type shown in Figure 6 to form a 3 layer web. The forming
element includes a forming wire. Dewatering occurs through the forming wire and is
assisted by a deflector and vacuum boxes. The forming wire, manufactured by Appleton
Wire of Appleton, Wisconsin, is a triple-layer square weave configuration having 90
machine-direction and 72 cross-machine-direction monofilaments per inch, respectively.
The monofilament diameter ranges from about 0.15 mm to about 0.20 mm. The forming
wire air permeability is about 29.40 scmm (1050 scfm). Flow through the forming wire
is impeded with photopolymer flow restriction members 1650 having a flower-like shape,
as shown in Figure 6. The flow restriction members 1650, combined, have a projected
area equal to about 10 percent of the projected area of the forming element 1600.
The difference in elevation D (Figure 7) is about 0.003 inch (0.076 millimeter).
[0147] The embryonic wet web is transferred from the forming element 1600, at a fiber consistency
of about 10% at the point of transfer, to a web support apparatus 2200 comprising
a photopolymer layer cast onto a woven reinforcing member in accordance with U.S.
Patent No. 4,528,239, Trokhan, issued on 9 July 1985. The woven reinforcing member
has about 59 filaments extending in the machine direction and about 44 filaments extending
in the cross machine direction, and can be made in accordance with U.S. Patent 4,191,609
issued March 4, 1980 to Trokhan.
[0148] The difference in elevation between 2261 AND 1231 (FIGURE 15) is about 0.003 inch
(0.076 millimeter). Further de-watering is accomplished by vacuum assisted drainage
until the web has a fiber consistency of about 28%; The patterned web is pre-dried
by air blow-through to a fiber consistency of about 65% by weight. The web is then
adhered to the surface of a Yankee dryer with a sprayed creping adhesive comprising
0.25% aqueous solution of Polyvinyl Alcohol (PVA).
[0149] The fiber consistency is increased to at least about 90% before dry creping the web
with a doctor blade. The doctor blade has a bevel angle of about 20 degrees and is
positioned with respect to the Yankee dryer to provide an impact angle of about 76
degrees; the Yankee dryer is operated at about 800 fpm (feet per minute) (about 244
meters per minute). The dry web is formed into roll at a speed of 650 fpm (200 meters
per minutes).
[0150] The decorative web is converted into a single-ply bath tissue paper. The single-ply
toilet tissue paper has a basis weight of about 29.51 g per square meter (about 18
pounds per 3000 square feet), and contains about 0.3% of the temporary wet strength
resin and about 0.1% of the debonder. The resulting single-ply tissue paper is bulky,
soft, absorbent, aesthetic and is suitable for use as bath tissues.
TEST METHODS:
Surface Smoothness:
[0151] The surface smoothness of a side of a paper web is measured based upon the method
for measuring physiological surface smoothness (PSS) set forth in the 1991 international
Paper Physics Conference, TAPP1 Book 1, article entitled "Methods for the Measurement
of the Mechanical Properties of Tissue Paper" by Ampulski et al. found at page 19,
which article is incorporated herein by reference. The PSS measurement as used herein
is the point by point sum of amplitude values as. described in the above article.
The measurement procedures set forth in the article are also generally described in
U.S. Patents 4,959,125 issued to Spendel and 5,059,282 issued to Ampulski et al, which
patents are incorporated herein by reference.
[0152] For purposes of testing the paper samples of the present invention, the method for
measuring PSS in the above article is used to measure surface smoothness, with the
following procedural modifications:
Instead of importing digitized data pairs (amplitude and time) into SAS software for
10 samples, as described in the above article, the Surface Smoothness measurement
is made by acquiring, digitizing, and statistically processing data for the 10 samples
using LABVIEW brand software available from National Instruments of Austin, Texas.
Each amplitude spectrum is generated using the "Amplitude and Phase Spectrum.vi" module
in the LABVIEW software package, with "Amp Spectrum Mag Vrms" selected as the output
spectrum. An output spectrum is obtained for each of the 10 samples.
[0153] Each output spectrum is then smoothed using the following weight factors in LABVIEW:
0.000246, 0.000485, 0.00756, 0.062997. These weight factors are selected to imitate
the smoothing provided by the factors 0.0039, 0.0077, 120, 1.0 specified in the above
article for the SAS program.
[0154] After smoothing, each spectrum is filtered using the frequency filters specified
in the above article. The value of PSS, in microns, is then calculated as described
in the above mentioned article. for each individually filtered spectrum. The Surface
Smoothness of the side of a paper web is the average of the 10 PSS values measured
from the 10 samples taken from the same side of the paper web. Similarly, the Surface
Smoothness of the opposite side of the paper web can be measured. The smoothness ratio
is obtained by dividing the higher value of Surface Smoothness, corresponding to the
more textured side of the paper web, by the lower value of Surface Smoothness, corresponding
to the smoother side of the paper web.
Basis Weight:
[0155] The basis weight of the web (macro basis weight) is measured using the following
procedure.
[0156] The paper to be measured is conditioned at 21.67-23.89 degrees Celsius (71-75 degrees
Fahrenheit) at 48 to 52 percent relative humidity for a minimum of 2 hours. The conditioned
paper is cut to provide twelve samples measuring 8.89 cm by 8.89 cm (3.5 inch by 3.5
inch). The samples are cut, six samples at a time, with a suitable pressure plate
cutter, such as a Thwing-Albert Alfa Hydraulic Pressure Sample Cutter, Model 240-10.
The two six sample stacks are then combined into a 12 ply stack and conditioned for
at least 15 additional minutes at 21.67 to 23.89°C (71 to 75 F) and 48 to 52 percent
humidity.
[0157] The 12 ply stack is then weighed on a calibrated analytical balance. The balance
is maintained in the same room in which the samples were conditioned. A suitable balance
is made by Sartorius Instrument Company, Model A200S. This weight is the weight in
grams of a 12 ply stack of the paper, each ply having an area of 79.01 squart cm (12.25
square inches).
[0158] The basis weight of the paper web (the weight per unit area of a single ply) is calculated
in units of g per 0.61 square meter (pounds per 3,000 square feet), using the following
equation:
Weight of 12 ply stack (grams) x 3000 x 144 sq inch per sq ft.
[0159] 
or simply:

Basis Weight of Background:
[0160] The basis weight of the background portion of the web is measured using the following
procedure. Samples of the background portion (samples do not include decorative indicia
or portions of decorative indicia) are cut from the paper web. The samples are cut
to be as large as possible without including decorative indicia. The area of each
sample is measured, and the sample is weighed. The basis weight of the background
is calculated by dividing the weight of the sample by the area of the sample. At least
three samples are measured and the results averaged to obtain the basis weight of
the background portion.
Basis Weight of Relatively Low Basis Weight Regions:
[0161] The basis weight of the relatively low basis weight regions is measured using the
following procedure.
[0162] The surface area of the relatively low basis weight regions is determined using a
computer, a scanner, and an image analysis software program. A suitable computer is
an Apple Macintosh Model 7200/90. A suitable scanner is an AGFA Arcus II brand scanner
available from AGFA-Gevaert N.V. of Belgium and having 600 dpi resolution. Suitable
image analysis software is NIH IMAGE Version 1.59 available from the National Institute
of Health.
[0163] The following procedure is used to scan samples and measure the surface area of the
relatively low basis weight regions in the sample. Samples are cut from a paper web,
each sample including a decorative indicia surrounded by the background. Each sample
is weighed to obtain the total weight, TW, of the sample
[0164] Each sample is mounted on a piece of black paper to provide a dark background during
scanning. The mounted sample is scanned using the AGFA Arcus II scanner. The images
are scanned into the computer using Adobe Photoshop Version 3.0.5 brand software.
The Adobe software is augmented with a FotoLook P.S. 2.07.2 brand plugin module available
from AGFA-Gevaert. The scan settings are set to: automatic, 600 dpi resolution, greyscale
(not color). The mounted sample is scanned along with a ruler to provide geometric
calibration.
[0165] The scanned image for each sample is then opened in the NIH IMAGE software and calibrated
with the ruler image. The calibration factor is about 235.2 pixels per millimeter.
The image analysis software is used to measure the total area of the sample based
on the perimeter of the sample.
[0166] The image is then smoothed twice using a 3x3 kernel prior to defining the outline
of the decorative indicia. The image is then density sliced to highlight pixels having
a greyscale value between 64 and 254. The magic wand tool is then used to outline
the decorative indicia, including all the relatively low basis weight regions included
in the indicia. The portions of the image outside the decorative indicia are discarded,
and the image of the decorative indicia is pasted to a new file. The magic wand is
then next used to cut away the relatively high basis weight portions (the cells) within
the decorative indicia, leaving only the portions of the image corresponding to the
relatively low basis weight regions. The image of the relatively low basis weight
regions is then density sliced to select those pixels having a greyscale value of
64-254. The software then calculates the area of the selected pixels to provide the
surface area of relatively low basis weight regions in the decorative indicia.
[0167] Once the surface area of the relatively low basis weight regions has been measured
using the image analysis software, the basis weight of the relatively low basis weight
regions is determined by solving for BW1 in the following equation:

where TW is the total weight of the sample having the decorative indicia, BW1 is
the basis weight of the relatively low basis weight regions, AREA1 is the area of
the relatively low basis weight regions measured using the image analysis software,
BW2 is the basis weight of the background region which can be measured from samples
cut from the background as described above, and AREA2 is the area of the background
of the sample. The value of AREA2 is the total area of the sample (calculated based
on the perimeter of the sample) minus the value of AREA1. Accordingly, the above equation
can be used to solve for the value of BW1. At least three samples are measured and
the results averaged to determine the basis weight of the relatively low basis weight
regions.
Macro-Caliper or Dry Caliper:
[0168] The Macro-Caliper or dry caliper is measured using the procedure for measuring dry
caliper disclosed in U.S. Patent 4,469,735, issued Sept. 4, 1984 to Trokhan, which
patent is incorporated herein by reference.
Bulk Density:
[0169] Bulk Density is the basis weight of the web divided by the web's macro-caliper, and
is reported in units of weight per unit volume. An appropriate conversion factor may
be used if the basis weight and the caliper are measured using different units.
Absorbent Capacity:
[0170] The absorbent capacity of a web is measured using the Horizontal Absorbative Capacity
Test disclosed in above referenced U.S. Patent 4,469,735.
Measurement of Web Support Apparatus Elevations:
[0171] The elevation difference between the elevation 231 of the first felt surface and
the elevation 261 of the web contacting surface 260 is measured using the following
procedure. The web support apparatus is supported on a flat horizontal surface with
the web patterning layer facing upward. A stylus having a circular contact surface
of about 1.3 square millimeters and a vertical length of about 3 millimeters is mounted
on a Federal Products dimensioning gauge (model 432B-81 amplifier modified for use
with an EMD-4320 W1 breakaway probe) manufactured by the Federal Products Company
of Providence, Rhode Island. The instrument is calibrated by determining the voltage
difference between two precision shims of known thickness which provide a known elevation
difference. The instrument is zeroed at an elevation slightly lower than the first
felt surface 230 to insure unrestricted travel of the stylus. The stylus is placed
over the elevation of interest and lowered to make the measurement. The stylus exerts
a pressure of about 0.24 grams/square millimeter at the point of measurement. At least
three measurements are made at each elevation. The measurements at each elevation
are averaged. The difference between the average values is the calculated to provide
the elevation difference.
[0172] The same procedure is used to measure the difference between elevations 1231 and
2261.
1. Papierbahn (20), die ineinander abgewandte Richtungen weisende Oberflächen (20, 24)
aufweist und einzelne, optisch unterscheidbare, dekorative Markierungen (200) umfasst,
die sich über einen gesamten Hintergrund-Abschnitt (100) in einem nicht-beliebigen,
sich wiederholenden Muster ausbreiten, wobei:
- die dekorativen Markierungen (200) einen oder mehrere Bereiche (220) umfassen, die
ein geringeres Flächengewicht als der umgebende Hintergrund-Abschnitt (100) der Bahn
(20) aufweisen, und wobei ,
- der Hintergrund-Abschnitt (100) mindestens einen Bereich (110) mit relativ hoher
Dichte und mindestens einen Bereich (130) mit relativ geringer Dichte aufweist.
2. Papierbahn gemäß Anspruch 1, dadurch gekennzeichnet, dass der Hintergrund-Abschnitt (100) umfasst einen kontinuierlichen Netz-Bereich (110)
mit relativ hoher Dichte und eine Vielzahl einzelner Bereiche (130) mit relativ geringer
Dichte, die sich über dem gesamten kontinuierlichen Netz-Bereich (110) ausbreiten.
3. Papierbahn gemäß einem der Ansprüche 1 bis 2, dadurch gekennzeichnet, dass der eine oder die mehreren Bereiche (220) mit relativ geringem Flächengewicht eine
oder mehrere Zellen (240) umschließen, die ein höheres Flächengewicht als die Bereiche
(220) aufweisen.
4. Papierbahn gemäß Anspruch 3, dadurch gekennzeichnet, dass jede Zelle (240) nicht mehr als die Hälfte ihrer äußeren Begrenzung mit jeder benachbart
angeordneten Zelle (240) aufweist, und dass mindestens einige der Zellen (240) eine
derartige äußere Begrenzung aufweisen, dass jede beliebige, gerade, durch die Zelle
(240) gezogene Linie die äußere Begrenzung der Zelle in nicht mehr als drei Stellen
schneidet.
5. Papierbahn gemäß einem der Ansprüche 3 bis 4, dadurch gekennzeichnet, dass die Zellen (240) mit relativ höherem Flächengewicht selektiv verdichtet sind, um
Bereiche (260) mit relativ hoher Dichte und Bereiche (280) mit relativ geringer Dichte
zu schaffen.
6. Papierbahn gemäß einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass die Papierbahn (20) zwischen ungefähr 5 und ungefähr 5.000 der dekorativen Markierungen
(200) pro Quadratmeter der Bahn, am bevorzugtesten zwischen ungefähr 25 und ungefähr
1.000 dekorative Markierungen (200) pro Quadratmeter der Bahn, aufweist.
7. Papierbahn gemäß einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass der Hintergrund-Abschnitt (100) mit relativ hohem Flächengewicht der Bahn mindestens
ungefähr 10.000 Bereiche (130) mit relativ geringer Dichte pro Quadratmeter der Bahn
umfasst.
8. Papierbahn gemäß einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass der Hintergrund-Abschnitt (100) mit relativ hohem Flächengewicht der Bahn einen Glattheits-Wert
von weniger als ungefähr 900 µm auf mindestens einer der ineinander entgegengesetzte
Richtungen weisenden Oberflächen der Bahn aufweist.
9. Papierbahn gemäß einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass der eine oder die mehreren Bereiche (220) mit relativ geringerem Flächengewicht ein
Flächengewicht aufweisen, welches kleiner als ungefähr 75 % des Flächengewichts des
umgebenden Hintergrund-Abschnitts (100), vorzugsweise kleiner als ungefähr 60 % des
Flächengewichts des umgebenden Hintergrund-Abschnitts (100), ist.
10. Papierbahn gemäß einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, dass mindestens einige Abschnitte der Bahn gekreppt sind.
11. Papierbahn gemäß einem der Ansprüche 1 bis 10, dadurch gekennzeichnet, dass sich ein oder mehrere einzelne Bereiche (135) mit relativ hoher Dichte überall in
jedem der Bereiche (130) mit relativ geringerer Dichte des Hintergrund-Abschnitts
(100) ausbreiten.
12. Papierbahn gemäß den Ansprüchen 5 bis 11, dadurch gekennzeichnet, dass jeder Bereich (280) mit relativ geringer Dichte der Zellen (240) eine Vielzahl einzelner
Bereiche (285) mit relativ höherer Dichte umgibt.
13. Papierstruktur dadurch gekennzeichnet, dass diese mehrere Lagen der Papierbahn gemäß einem der Ansprüche 1 bis 12 umfasst.
14. Verfahren zur Herstellung einer Papierbahn gemäß einem der Ansprüche 1 bis 12,
gekennzeichnet durch die Schritte:
- Bereitstellen einer Vielzahl von Fasern, die in einem flüssigen Träger in Suspension
gehalten sind,
- Bereitstellen eines Faser-festhaltenden Formgebungs-Elements (1600) mit flüssigkeitsdurchlässigen
Bereichen und Strömungs-Beschränkungs-Elementen (1650), die eine Form entsprechend
den einzelnen, optisch unterschiedlichen, dekorativen Markierungen (200) aufweisen,
die auf der Bahn (20) zu bilden sind,
- Absetzen der Fasern und des flüssigen Trägers auf dem Formgebungs-Element (1600),
- Ableiten des flüssigen Trägers durch das Formgebungs-Element in zwei simultanen Stufen, um eine unentwickelte Bahn (543)
zu bilden, die aufweist mindestens einen Bereich (100) mit relativ hohem Flächengewicht
und dekorative Markierungen (200), die einen oder mehrere Bereiche (220) mit relativ
geringem Flächengewicht umfassen,
- Bereitstellen einer Bahn-Träger-Vorrichtung (2200), die eine Bahn-profilierende
Oberfläche (2260) aufweist,
- Überführen der Bahn von dem Formgebungs-Element (1600) zu der Bahn-profilierenden
Oberfläche (2260) der Bahn-Träger-Vorrichtung (2200),
- selektives Verdichten mindestens eines Abschnitts des Bereichs (100) mit relativ
hoher Flächenmasse, um ein nicht-beliebiges, sich wiederholendes Muster von ersten
verdichteten Bereichen (130) und von zweiten verdichteten Bereichen (110) zu schaffen,
wobei die zweiten verdichteten Bereiche (110) eine höhere Dichte als die ersten verdichteten
Bereiche (130) in dem Bereich (100) mit relativ hohem Flächengewicht aufweisen, und
- fakultatives Kreppen der Bahn.
15. Verfahren gemäß Anspruch 14,
dadurch gekennzeichnet, dass die Bahn-Träger-Vorrichtung (2200) umfasst:
- eine Entwässerungs-Filz-Lage (2220), welche eine erste Bahn-berührende Oberfläche
(2230, 1230) aufweist, die in einer ersten Höhenlage (2231, 1231) angeordnet ist,
und
- eine wasserundurchlässige Bahn-profilierende Lage (2250), welche mit der Entwässerungs-Filz-Lage
(2220) verbunden ist, und welche eine zweite Bahn-berührende Oberfläche (2260) in
einer zweiten Höhenlage (2261) bereitstellt,
- wobei die Differenz der Höhenlagen zwischen der ersten Bahnberührenden Oberfläche
(2230, 1230) und der zweiten Bahnberührenden Oberfläche (2260), falls vorhanden, kleiner
als die Dicke der unentwickelten Bahn am Punkt der Überführung ist.
16. Verfahren gemäß einem der Ansprüche 14 bis 15, dadurch gekennzeichnet, dass die Fasern umfassen relativ lange Fasern mit einer durchschnittlichen Faserlänge
von mehr als oder gleich 20 mm und relativ kurze Fasern mit einer durchschnittlichen
Faserlänge von weniger als 2,0 mm.
17. Verfahren gemäß einem der Ansprüche 15 bis 16, dadurch gekennzeichnet, dass die Entwässerungs-Filz-Lage (2220) eine Nonwoven-Schicht (2240) aus natürlichen oder
synthetischen Fasern umfasst, welche mit einer aus gewebten Fasern (2244) gebildeten
Träger-Struktur verbunden ist, und welche die erste Bahn-berührende Oberfläche (2230)
in der ersten Höhenlage (2231) bereitstellt.
18. Verfahren gemäß einem der Ansprüche 15 bis 16, dadurch gekennzeichnet, dass die Entwässerungs-Filz-Lage (2220) aus einem gewebten Stoff (1220) hergestellt ist,
der Fäsern (1242) in Maschinen-Richtung und Fasern (1241) senkrecht zur Maschinen-Richtung
umfasst, und der die erste Bahn-berührende Oberfläche (1230) in der ersten Höhenlage
(1231) bereitstellt.
19. Verfahren gemäß Anspruch 18, dadurch gekennzeichnet, dass die erste Bahn-berührende Oberfläche in einer ersten Höhenlage (1231) durch einzelne
Höcker-Oberflächen (1230) gebildet wird, die sich an Kreuzungs-Punkten der Fasern
(1241, 1242) befinden.
20. Verfahren gemäß einem der Ansprüche 14 bis 19, dadurch gekennzeichnet, dass die Bahn-profilierende Oberfläche (2260) ein kontinuierliches Netz ist, das einzelne
Öffnungen (2270) bildet.
21. Verfahren gemäß einem der Ansprüche 14 bis 20, dadurch gekennzeichnet, dass die Profilierung der Bahn-profilierenden Oberfläche (2260) auf die überführte Bahn
(545) durch Fördern der Bahn von der Bahn-Träger-Vorrichtung (2200) durch einen Walzenspalt
(800) zu der Trocknungs-Oberfläche eines Yankee-Trockners (880) übertragen wird.
22. Verfahren gemäß Anspruch 21, dadurch gekennzeichnet, dass die Bahn von der Oberfläche (875) des Yankee-Trockners (880) mit einer Rakel (1000)
gekreppt wird, welche einen Stell-Winkel von 25 ° aufweist und in Bezug zum Yankee-Trockner
so angeordnet ist, dass ein Auftreff-Winkel von ungefähr 81° gebildet wird.
1. Nappe de papier (20) présentant des surfaces dirigées de façon opposée (20, 24), et
comprenant des marques décoratives (200) discrètes, visuellement distinctives, dispersées
dans toute une portion de fond (100) selon un motif répétitif non aléatoire, dans
laquelle:
- lesdites marques décoratives (200) comprennent une ou plusieurs régions (220) qui
présentent un grammage inférieur à celui de la portion de fond (100) environnante
de la nappe (20), et en ce que
- ladite portion de fond (100) présente au moins une région (110) d'une densité relativement
élevée et au moins une région (130) d'une densité relativement faible.
2. Nappe de papier selon la revendication 1, caractérisée en ce que ladite portion de fond (100) présente une région réticulaire continue de densité
relativement élevée (110) et une pluralité de régions discrètes de densité relativement
faible (130) dispersées dans toute la région réticulaire continue (110).
3. Nappe de papier selon l'une quelconque des revendications 1 à 2, caractérisée en ce que lesdites une ou plusieurs régions (220) de grammage relativement inférieur entourent
une ou plusieurs cellules (240) ayant un grammage supérieur à celui desdites régions
(220).
4. Nappe de papier selon la revendication 3, caractérisée en ce que chaque cellule (240) ne partage pas plus de la moitié de son périmètre avec une cellule
adjacente quelconque (240), et en ce que, au moins certaines desdites cellules (240) présentent un périmètre tel que toute
ligne droite tracée à travers la cellule (240) coupe le périmètre de la cellule en
pas plus de trois positions.
5. Nappe de papier selon l'une quelconque des revendications 3 à 4, caractérisée en ce que lesdites cellules à grammage relativement élevé (240) sont densifiées sélectivement
afin de fournir des régions de densité relativement élevée (260) et des régions de
densité relativement faible (280).
6. Nappe de papier selon l'une quelconque des revendications 1 à 5, caractérisée en ce que la nappe de papier (20) comprend les marques décoratives (200) à raison d'entre environ
5 et environ 5 000 par mètre carré de la nappe, de manière tout particulièrement préférée
entre environ 25 et environ 1 000 marques décoratives (200) par mètre carré de la
nappe.
7. Nappe de papier selon l'une quelconque des revendications 1 à 6, caractérisée en ce que la portion de fond à grammage relativement élevé (100) de la nappe, comprend au moins
environ 10 000 régions de densité relativement faible (130) par mètre carré de la
nappe
8. Nappe de papier selon l'une quelconque des revendications 1 à 7, caractérisée en ce que la portion de fond à grammage relativement élevé (100) de la nappe, présente une
valeur de lissé inférieure à environ 900 micromètres sur au moins une des surfaces
dirigées de façon opposée de la nappe.
9. Nappe de papier selon l'une quelconque des revendications 1 à 8, caractérisée en ce que lesdites une ou plusieurs régions (220) de grammage relativement inférieur, présentent
un grammage qui est inférieur à environ 75 pourcent du grammage de la portion de fond
(100) environnante, de préférence inférieur à environ 60 pourcent du grammage de la
portion de fond (100) environnante.
10. Nappe de papier selon l'une quelconque des revendications 1 à 9, caractérisée en ce qu'au moins certaines portions de la nappe sont crêpées.
11. Nappe de papier selon l'une quelconque des revendications 1 à 10, caractérisée en ce qu'une ou plusieurs régions discrètes de densité relativement élevée (135) sont dispersées
dans chacune-des régions de densité relativement inférieure (130), de ladite portion
de fond (100).
12. Nappe de papier selon les revendications 5 à 11, caractérisée en ce que chaque région de densité relativement faible (280) desdites cellules (240) entoure
une pluralité de régions discrètes de densité relativement supérieure (285).
13. Structure de papier, caractérisée en ce qu'elle comprend des plis multiples de la nappe de papier selon l'une quelconque des
revendications 1 à 12.
14. Procédé de production d'une nappe de papier selon l'une quelconque des revendications
1 à 12,
caractérisée par les étapes de :
- fournir une pluralité de fibres en suspension dans un véhicule liquide,
- fournir un élément formeur retenant les fibres (1600) présentant des zones perméables
aux liquides et des éléments de restriction d'écoulement (1650) qui présentent une
forme correspondante aux marques décoratives discrètes, visuellement distinctives
(200), à former sur la nappe (20),
- déposer les fibres et le véhicule liquide sur l'élément formeur (1600),
- évacuer le véhicule liquide à travers l'élément formeur en deux étapes simultanées
afin de former une nappe embryonnaire (543) présentant au moins une région à grammage
relativement élevé (100) et des marques décoratives (200) comprenant une ou plusieurs
régions à grammage relativement faible (220),
- fournir un appareil (2200) soutenant la nappe, présentant une surface (2260) produisant
un motif sur la nappe,
- transférer la nappe de l'élément formeur (1600) vers la surface (2260) produisant
un motif sur la nappe de l'appareil soutenant la nappe (2200),
- densifier sélectivement au moins une portion de la région à grammage relativement
élevé (100) afin de fournir un motif répétitif non aléatoire de premières régions
densifiées (130) et de deuxièmes régions densifiées (110), les deuxièmes régions densifiées
(110) présentant une densité supérieure à celle des premières régions densifiées (130)
dans la région à grammage relativement élevé (100), et
- éventuellement, crêper la nappe.
15. Procédé selon la revendication 14,
caractérisé en ce que ledit appareil (2200) soutenant la nappe comprend:
- une couche de feutre d'égouttage (2220), qui présente une première surface en contact
avec la nappe (2230, 1230), disposée au niveau d'une première élévation (2231, 1231),
et
- une couche imperméable à l'eau produisant un motif sur la nappe (2250), qui est
jointe à la couche de feutre d'égouttage (2220), et qui fournit une deuxième surface
en contact avec la nappe (2260) au niveau d'une deuxième élévation (2261),
- la différence d'élévation entre la première surface en contact avec la nappe (2230,
1230) et la deuxième surface en contact avec la nappe (2260), s'il y en a une, étant
inférieure à l'épaisseur de la nappe embryonnaire au point de transfert.
16. Procédé selon l'une quelconque des revendications 14 à 15, caractérisé en ce que lesdites fibres comprennent des fibres relativement longues présentant une longueur
moyenne de fibre supérieure ou égale à 20 mm, et des fibres relativement courtes ayant
une longueur moyenne de fibre inférieure à 2,0 mm.
17. Procédé selon l'une quelconque des revendications 15 à 16, caractérisé en ce que, la couche de feutre d'égouttage (2220) comprend une natte non tissée (2240) de fibres
naturelles ou synthétiques, qui est jointe à une structure support formée de filaments
tissés (2244), et qui fournit la première surface en contact avec la nappe (2230)
au niveau de la première élévation (2231).
18. Procédé selon l'une quelconque des revendications 15 à 16, caractérisé en ce que la couche de feutre d'égouttage (2220) est constituée d'un tissu tissé (1220) comprenant
des filaments dans la direction de la machine (1242) et des filaments dans la direction
transversale à la machine (1241), et fournit la première surface en contact avec la
nappe (1230) au niveau de la première élévation (1231).
19. Procédé selon la revendication 18, caractérisé en ce que la première surface en contact avec la nappe au niveau d'une première élévation (1231)
est fournie par des surfaces protubérantes discrètes (1230) situées en des points
de croisement des filaments (1241, 1242).
20. Procédé selon l'une quelconque des revendications 14 à 19, caractérisé en ce que la surface (2260) produisant un motif sur la nappe est un réseau continu définissant
des ouvertures discrètes (2270).
21. Procédé selon l'une quelconque des revendications 14 à 20, caractérisé en ce que le motif de ladite surface (2260) produisant un motif sur la nappe, est conféré à
la nappe transférée (545) en transportant la nappe de l'appareil soutenant la nappe
(2200) à travers une ligne de pinçage (800) vers la surface de séchage d'un sécheur
de type Yankee (880).
22. Procédé selon l'une quelconque la revendication 21, caractérisé en ce que la nappe est crêpée à partir de la surface (875) du sécheur de type Yankee (880)
avec une racle (1000) qui présente un angle de biseau de 25 degrés, et qu'elle est
disposée par rapport au sécheur de type Yankee afin d'offrir un angle d'impact d'environ
81 degrés.