Field of the Invention
[0001] This invention relates to fibrous absorbent structures and in particular to reinforced
airlaid fibrous bodies.
Background of the Invention
[0002] Absorbent fibrous structures comprised of low strength absorbent materials such as
airlaid wood pulp fibers are well known in the disposable absorbent bandage art. In
certain of these prior art fibrous pad structures it has been found desirable to employ
one or more internally located plies of tissue paper or other web materials which
are substantially impervious to the passage of fibers to act, for example, as a reinforcing
agent, as a fluid baffle to distribute absorbed fluids within the absorbent fluff
structure, as a partitioning agent or the like. Addition of such internal plies which
have a width substantially equal to that of the absorbent fibrous webs located on
the uppermost and lowermost surfaces thereof has typically been provided by utilizing
a multiplicity of discrete forming zones with a separate fiber supply source for each
zone. However, the multiple forming zone approach typically employed by such prior
art systems requires considerable converting line space and involves a duplication
of disintegrating and air layering equipment for each absorbent fibrous layer employed
in the resultant structure. Furthermore, altering the position of the internal ply
relative to the uppermost and lowermost surfaces of the finished absorbent pad typically
requires a complex adjustment procedure for each fiber deposition zone in the system.
[0003] Accordingly, it is an object of the present invention to provide method and apparatus
for forming an airlaid fiber impervious fibrous fluff web provided with a substantially
planar fiber impervious internal reinforcing ply whose width is substantially coextensive
with that of the web.
[0004] It is a preferred object of the present invention to provide method and apparatus
for easily altering the position of the internal ply relative to the uppermost and
lowermost surfaces of the absorbent pad in question.
[0005] It is yet another object of the present invention to provide method and apparatus
for the continuous formation of an internally reinforced airlaid fibrous fluff web
in a single fibre deposition zone, the reinforcement comprising a substantially planar
fiber-impervious internal reinforcing ply having substantially the same width as said
fibrous web, and the deposition zone having an overall length no greater than that
required to form an identical absorbent pad of the comparable basis weight without
said center ply.
Summary of the Invention
[0006] In one method aspect of the present invention the aforementioned objectives are accomplished
by carrying out the steps of:
(a) continuously feeding said substantially planar reinforcing ply (2) in a first
direction in a first plane;
(b) introducing said moving reinforcing ply into a single fiber deposition zone in
which is disposed a foraminous support surface (11) moving in said first direction
while the ply is oriented so that the direction of fiber flow is substantially parallel
to the width of said ply, to vacuum form on said support surface, a first portion
(21) of said airlaid fibrous fluff web;
(c) guiding said moving reinforcing ply into contact with a first equal length leg
portion (58) of the trailing surface of a planar isosceles right angled triangle,
(52) said first equal length leg portion being oriented perpendicular to said first
direction of travel of said ply (20);
(d) wrapping said moving reinforcing ply about opposite surfaces of said planer right
triangle (52) by passing said ply about the hypotenuse thereof;
(e) restoring said moving ply to said first direction of travel by passing said moving
ply about the second equal length leg portion (56) of said triangle (52), thereby
causing said ply to assume a planar condition in a second plane perpendicular to said
first plane, said ply being positioned with its lowermost surface immediately adjacent
said first airlaid fibrous fluff web portion (21);
(f) exposing the uppermost surface of said moving reinforing ply to said fiber deposition
zone while in a planar condition to vacuum form a second portion (22) of said airlaid
fibrous fluff web adjacent the uppermost surface of said reinforcing ply (20); and
(g) removing said ply and said airlaid web portions from said fiber deposition zone.
[0007] In a second method aspect of the present invention the objectives are accomplished
by carrying out the steps of:
(a) continuously feeding said substantially planar reinforcing ply (20) in a first
direction in a first plane;
(b) guiding said moving reinforcing ply about a first direction changing means (5)
and into contact with the leading surface of a first planar isosceles right angled
triangle (2) said triangle having its altitude oriented perpendicular to said first
direction of travel of said ply;
(c) wrapping said moving reinforcing ply about opposite surfaces of said first planar
triangle;
(d) restoring said moving ply to its first direction of travel by directing said ply
about the apex of said first triangle while maintaining the lateral edge portions
of said moving ply in contact with the leading and trailing surfaces of said first
triangle, thereby causing said ply to fold about itself in a second plane perpendicular
to said first plane;
(e) introducing said moving reinforcing ply to a single fiber deposition zone in which
is disposed a foraminous support surface (11) moving in said first direction while
the ply is in a folded configuration, to vacuum form on said support surface, a first
portion (21) of said airlaid fibrous fluff web;
(f) wrapping said moving reinforcing ply about opposite surfaces of a second isosceles
triangle (4) identical to and longitudinally aligned with said first triangle (2)
and having its altitude oriented perpendicular to said first direction of travel such
that the lateral edges of said moving ply are guided on opposite sides of the apex
of said second triangle as said moving ply is directed about the apex thereof, the
lateral edges of said moving ply being maintained in contact with the leading and
trailing surfaces of said second triangle, thereby restoring said ply to a planar
condition;
(g) directing said moving reinforcing ply about a second direction changing means
(6) to restore it to said first direction of travel and to bring the lowermost surface
thereof into contact with the first airlaid fibrous fluid portion (21)
(h) exposing the uppermost surface of said moving reinforcing ply to said fiber deposition
zone while in a planar condition to vacuum form a second portion (22) of said airlaid
fibrous fluff web adjacent the uppermost surface of said reinforcing ply; and
(i) removing said ply and said airlaid web portions from said fiber deposition zone.
Brief Description of the Drawings
[0008] While the specification concludes with claims particularly pointing out and distinctly
claiming the subject matter which is regarded as forming the present invention, it
is believed that the invention will be better understood from the following description
taken in connection with the accompanying drawings in which:
Figure 1 is a simplified cross-sectional illustration of a pad forming mechanism employing
a preferred embodiment of the present invention taken along Section Line 1-1 in Figure
2;
Figure 2 is a complete side elevation view of the pad forming mechanism illustrated
in cross-section Figure 1.
Figure 3 is an enlarged cross-sectional illustration taken along Section line 3-3
in Figure 2;
Figure 4 is a simplified perspective view of the pad forming mechanism illustrated
in Figures 1-3;
Figure 5 is a simplified schematic illustration of the folding board portion of the
mechanism utilized in a preferred embodiment of the present invention;
Figure 6 is a discharge end view of the folding board illustrated in Figure 5;
Figure 7 is a plan view of the folding board illustrated in Figure 5; and
Figure 8 is a simplified perspective view of yet another folding board suitable for
use in the present invention.
Detailed Description of the Invention
[0009] Figure 1 is a plan view of a preferred embodiment of the present invention wherein
a wet strength tissue ply 20 is incorporated intermediate the uppermost and lowermost
surfaces of an absorbent pad for a disposable absorbent article to improve its in
use integrity. As can be seen more clearly from Figure 2, the wet stength tissue ply
20 is directed about a folding board mechanism 1 prior to entry of the tissue ply
into a fiber deposition chute 12 fed by a source of discrete fibrous material from
e.g. a fiber disintegration apparatus (not shown). The lower region of the chute 12
defines a chamber wherein a lowermost layer of absorbent airfelt 21 is formed beneath
the surface of the tissue ply 20 and an uppermost layer of airfelt 22 is formed adjacent
its uppermost surface. In a particularly preferred embodiment of the present invention,
a layer of wet strength tissue paper 23 is employed adjacent the lowermost surface
of the layer of airfelt 21, and an uppermost layer of tissue paper 24 is employed
adjacent the uppermost surface of the layer of airfelt 22.
[0010] In the embodiment illustrated in Figures 1 and 2 the folding board 1 comprises a
pair of identical planar isosceles triangles 2, 4 having an included angle of approximately
90° at their respective apexes, connected to one another at their altitudes by means
of a vertical planar member 3. A layer of reinforcing wet strength tissue paper 20
having a width W substantially equal to that of the airfelt layers 21, 22 is preferably
fed in the same direction and at the same velocity V as the foraminous supporting
surface 11. The tissue ply 20 is caused to alter its path of travel from a horizontal
direction to a vertical direction by virtue of being wrapped about direction changing
roller 5 located near the base of the isosceles right triangle 2 forming a portion
of the folding board 1. While the centerline of the moving tissue ply 20 is caused
to coincide with the altitude of the isosceles right triangle 2 in the illustrated
embodiment, the lateral edge portions of the ply are caused to remain in contact with
both the leading and trailing surfaces of the triangle by virtue of angular guides
7, 8 located adjacent the interior corners formed between vertical planar member 3
and the planar triangle 2. When the tissue ply 20 is forced to resume its original
direction of travel about the apex of the isosceles right triangle 2, the angular
guide members 7, 8 force the tissue ply 20 to assume an inverted U-shape as illustrated
in the cross-section of Figure 3. While the vertical planar member 3 does conveniently
serve to maintain planar isosceles triangles 2, 4 in longitudinal alignment with one
another, its presence is not essential to guide the inverted U-shaped tissue ply 20
intermediate the triangles 2, 4. The inverted U-shaped shroud 28 which connects angles
9, 10 to one another serves to prevent fibers within the deposition chute 12 from
collecting on the inverted U-shaped tissue ply 20 prior to passage of the ply through
the limited clearance corners formed between angles 9, 10, triangle 4 and vertical
planar member 3. Collection of fibers on the inverted U-shaped tissue ply 20 could
cause jamming or tearing at these points.
[0011] The tissue ply 20 is introduced into the fiber deposition chute 12 while in the inverted
U-shape in order to permit formation of a substantially planar lowermost layer of
airfelt 21 which lies adjacent the lowermost surface of the tissue ply 20 in the finished
absorbent pad embodiment. Internal airflow baffling techniques well known in the art
may be employed within the vacuum chamber 26 to minimize any discontinuities in the
cross-machine direction uniformity of the airfelt layer 21 which might otherwise occur
due to the minor obstruction presented by the thin U-shaped shroud 28. In a particularly
preferred embodiment, the lowermost layer of airfelt 21 is formed directly over a
layer of envelope tissue 23 similar to that utilized as the reinforcing ply 20 in
the forwardmost portion 13 of the fiber deposition chute 12. As can be seen in Figure
2, the vacuum chamber 25 located adjacent the lowermost surface of the moving foraminous
support member 11 is preferably divided into two distinct segments 26, 27 by means
of an adjustable dividing wall 19 which may be advanced or retarded in the machine
direction. The vacuum chamber 25 is preferably segmented as outlined above in order
to permit the application of differing vacuum levels between the leading portion 13
of the fiber deposition chute 12 and the trailing portion 14, since the trailing portion
encounters more resistance to air flow than the leading portion due to the presence
of the fibrous layer 21 and the reinforcing tissue ply 20 during formation of the
uppermost layer of airfelt 22.
[0012] As is apparent from Figures 1 and 2, the tissue ply 20 is maintained in an inverted
U-configuration until the desired thickness of airfelt layer 21 has been obtained.
The relative and total thickness of the respective airfelt layers 21 and 22 is controllable
not only by the rate of fiber deposition within the chute 12, but also by the level
of vacuum applied beneath the moving formaminous support member 11 in vacuum chamber
segments 26 and 27, the machine direction positioning of the segmenting wall 19 within
the vacuum chamber 25, and the machine direction positioning of the planar isosceles
right triangle 4 connected to vertical planar member 3. Furthermore, baffle plates
15 and 16 which extend across the entire width of the fiber deposition chute 12, and
which may be adjusted about pivot points 17 and 18, may also be employed to direct
the flow of fibers toward either the leading portion 13 or the trailing portion 14
of the deposition chute 12, depending upon the desired split between uppermost layer
22 and lowermost layer 21.
[0013] Angular guides 9 and 10 force the tissue ply 20 to remain in contact with the leading
surface of isosceles right triangle 4 which is identical in size and shape to the
isosceles right triangle 2 as the centerline of a tissue ply 20 is directed about
the apex of triangle 4. This in turn forces the tissue ply 20 to resume a planar configuration
as it passes the base portion of the trailing surface of the triangle 4. Direction
changing roll 6 restores the tissue ply 20 to its original direction of travel and
exposes the uppermost surface of the ply to the deposition of fibers in the downstream
portion 14 of the fiber deposition chute 12. A fibrous airlaid web 22 is thus formed
adjacent the uppermost surface of the tissue ply 20 prior to passage of the assemblage
from the fiber deposition chute 12. A wet strength tissue ply 24 is preferably thereafter
brought into contact with the uppermost surface of the absorbent airfelt layer 22
about direction changing roller 30 as shown in Figure 2 to form a reinforced fibrous
structure encapsulated on both sides by wet strength tissue piies 23, 24.
[0014] As has been pointed out earlier herein, the relative position of the internally located
tissue ply 20 may be adjusted intermediate the uppermost and lowermost surfaces of
the resultant absorbent pad structure by advancing or retarding the position of the
folding board 1 and the direction changing rollers 5, 6 which are preferably mounted
thereto within the fiber deposition chute 12. This of course necessitates a corresponding
adjustment of angular guides 7, 8, 9 and 10 and shroud 28 in order to maintain the
tissue ply 20 in contact with the surfaces of triangles 2, 4. The U-shaped shroud
28 illustrated in cross-section in Figure 3 is preferably employed in the practice
of the present invention to avoid the collection of fibers on the uppermost surfaces
of the wet strength tissue ply 20 prior to direction of the ply intermediate angular
guides 9 and 10 located at the interior corners formed between isosceles triangle
4 and vertical planar member 3. This is necessary to avoid hangup or jamming of the
ply within the relatively tight clearances provided intermediate the guides 9 and
10 and the interior corners formed by triangle 4 and vertical planar member 3. As
will thus be apparent to those skilled in the art, the shroud 28 must also be adjustable
such that adjustment of the triangle 4 in the machine direction will not result in
exposure of the inverted U-shaped tissue ply 20 to the stream of fibers present in
the leading portion 13 of fiber deposition chute 12. In a most preferred embodiment
of the present invention, separating wall 19 in vacuum chamber 25 is adjustable so
as to vertically coincide with the position ultimately assumed by isosceles triangle
4 within the deposition chute 12.
[0015] Figure 4 is a simplified perspective illustration of the embodiment of the present
invention illustrated in Figures 1-3. Selected portions of the fiber deposition chute
12 have been broken away to illustrate with maximum clarity the present pad forming
operation.
[0016] The geometry of the folding board 1 illustrated in Figures 1-4 is more clearly set
forth in Figures 5-7. While it is not essential that the folding board 1 be comprised
of solid sheet stock as illustrated in Figure 5, the folding board preferably comprises
a pair of planar isosceles right triangles 2, 4 connected to one another by means
of a vertical planar member 3 corresponding in height to the altitude of each isosceles
triangle. In order to minimize the vertical height requirement for a folding board
of the present invention, it is preferable that the centerline of the tissue ply 20
be made to coincide with the altitude of both triangles during its passage over the
folding board. Thus, in the simple embodiment illustrated in Figure 4 the included
right angle a of triangle 2 is surrounded by equal length legs 42, 43 while the included
right angle a of identical triangle 4 is surrounded by equal length legs 45, 46. The
base 44 of isosceles triangle 2 and the base 47 of isosceles triangle 4 connect the
respective equal length leg segments of the triangles. Lines 40 and 41 illustrated
in Figure 5 represent the altitudes of right triangles 2 and 4, respectively. Thus,
the angle β in each case amounts to 90 degrees, and the included right angle a of
each triangle is bisected by its respective altitude. The angle y between the altitude
40 of right triangle 2 and the base of vertical planar member 3 and the angle 8 between
the altitude 41 of triangle 4 and the base of vertical planar member 3 in the illustrated
embodiment are also equal to 90 degrees.
[0017] The principle upon which the folding board 1 illustrated in Figures 1-7 operates
is that each point on the incoming ply 20 must travel the same linear distance in
traversing the surface of the forming board from entry thereon near the base 44 of
isosceles right triangle 2 until its exit therefrom near the base 47 of isosceles
right triangle 4. The paths followed by a pair of corresponding points located on
opposite sides of the ply centerline is represented by lines 48 and 49 in Figure 5.
The principle is further illustrated in Figure 6 which is a discharge end view of
the folding board 1 illustrated in Figure 5. The sum of any given pair of lines A"
+ B
" must be constant, where An is any line parallel to the altitude 41 of the triangle
and B
" is the corresponding horizontal distance of the line An from the altitude 41.
[0018] As should be clear from Figure 7 which is a plan view of the folding board 1 illustrated
in Figure 5, the lowermost layer of absorbent fibers 21 is formed while the ply 20
is in the inverted U-configuration intermediate triangles 2, 4. As will be appreciated
by those skilled in the art, it is desirable to minimize the width occupied by the
ply 20 as it passes through the fiber deposition chute 12 in the inverted U-configuration
in order to minimize any cross-machine direction non-uniformity in the lowermost airlaid
web 21 formed adjacent its lowermost surface.
[0019] While it should be observed that the angle 0 formed between triangle 2 and vertical
planar member 3 and the angle 0 formed between triangle 4 and vertical planar member
3 amounts to 90 degrees in the embodiment illustrated in Figures 1-7, it should be
noted that the angles 0 and 0 need not equal one another, nor is it required that
either angle be a right angle. The angle of infeed and outfeed of the tissue ply 20
may be varied as desired, provided only that the angles employed permit the tissue
ply to be maintained in substantial surface contact with the triangles at the inside
corners formed between triangles 2, 4 and vertical planar member 3. It should further
be noted that vertical planar member 3 is not an essential portion of the present
folding board 1, but rather is employed in a preferred embodiment of the present invention
as a means of securing the triangles in longitudinal alignment with one another, a
feature which is critical to the practice of the present invention.
[0020] It is possible to substitue other suitable means of maintaining the tissue ply 20
in contact with the inside corners formed between triangles 2, 4 and vertical planar
member 3 for the angular guides 7, 8, 9 and 10 illustrated in Figures 1 and 2. Thus,
rods, roJls, or any other suitable mechanism may be employed, provided only that the
overall distance traveled by any given point on the tissue ply remain substantially
constant across the width of the ply. In this regard, it should be noted that sharp
edges are preferably removed from portions of the folding board 1 where stress concentrations
are particularly high in order to avoid cutting or tearing of the tissue ply by the
tensional forces to which it is subjected as it is drawn through the folding board.
In this regard, a slight relief is preferably provided at the leading and trailing
surfaces of the triangle 2, 4 at their respective apexes. While this causes a very
slight deviation in the theoretical constant length criteria described above, the
practical and beneficial effect is to minimize the tendency of the ply 20 to rip or
tear at points of stress concentration.
[0021] Figure 8 represents yet another particularly preferred embodiment of a folding board
50 which may be employed in the practice of the present invention in a system similar
to that illustrated in Figures 1 and 2. In the embodiment illustrated in Figure 8,
a vertical support member 57 is joined to one of the equal length leg segments 58
of an isosceles right triangle 52 having its included right angle 1/1 located intermediate
equal length legs 58, 56. The triangle 52 preferably forms an angle Ω of 90 degrees
with vertical planar member 57. In practice, a ply of reinforcing tissue 20' having
a width W' is fed in a vertical plane in a direction parallel to the direction of
travel of the foraminous support member 11 illustrated in Figures 1 and 2. The incoming
ply 20' is wrapped about leg 58 of the isosceles right triangle 52 such that it contacts
the trailing surface of the triangle and its borders parallel the equal length leg
56. The ply 20' is thereafter directed about the hypotenuse 54 of the planar triangle
52 and downwardly in a direction parallel to leg 58 while in contact with the leading
surface of the triangle. The ply 20' is finally directed about equal length leg 56
of the triangle and thereafter continues in a manner similar to that illustrated in
Figures 1 and 2. The particular embodiment illustrated in Figure 8 offers the advantage
that the tissue ply 20' does not require the use of any external guides to hold it
in intimate contact with the surfaces of the isoceles right triangle 52, but rather
is wrapped tightly thereabout by means of the tension employed to draw the ply through
the folding board 50. Furthermore, there is no interruption of the fiber forming zone
in the leading portion 13 of the fiber deposition chute 12, since the vertical support
member 57 may be located adjacent the edge of the fibrous web 21. Accordingly, it
is feasible to obtain a uniform cross-machine direction basis weight and profile in
the fibrous airfelt web 21 formed adjacent the lowermost surface of the ply 20'. The
embodiment illustrated in Figure 8 does, however, require greater overhead clearance
at the fiber deposition chute 12 due to the fact that the ply 20' is not folded upon
itself, as in the case of the embodiment illustrated in Figures 1-3.
[0022] In a particularly preferred embodiment of the present invention, the outermost tissue
plies 23 and 24 illustrated in Figures 1 and 2 may be somewhat wider than the tissue
ply 20 and the airfelt web portions 21 and 22. In such an embodiment the lateral edge
portions of plies 23 and 24 may be secured to one another by folding, by adhesives,
or by other means well known in the art to form a continuous encapsulating envelope.
If desired, a continuous layer of moisture-pervious topsheet material may be secured
in superposed relation to the continuous envelope. Absrobent pad segments of predetermined
length are thereafter cut from the continuous envelope. The absorbent pad segments
are preferably rotated 90° prior to securement to a continuous web of moisture-impervious
backsheet material about their periphery to form a continuous web of disposable absorbent
bandages, such as diapers. Individual diapers are thereafter cut from the continuous
web intermediate the absorbent pad segments. U.S. Patent 3,952,745 issued to Duncan
on April 27, 1976 and incorporated herein by reference is generally representative
of such a construction. Aligning the machine direction of the tissue plies 20, 23
and 24 parallel to the waistband portions of the diaper in this manner is generally
desirable since it aligns the tissue's direction of maximum strength with the direction
in which the greatest tensile loads are typically applied in use.
[0023] It is noteworthy that the invention disclosed herein may be utilized to provide plies
which are perforate or imperforate and which are either continuous or discontinuous
in the cross machine direction intermediate a pair of fibrous webs in a single fiber
deposition zone. Furthermore, multiple plies may be simultaneously fed utilizing an
embodiment of the present invention, or multiple stages of the present invention may
be employed to provide multiple reinforcing plies within a single structure, each
ply being separated from the next by a fibrous layer. In addition, it should be noted
that although in the embodiment illustrated in Figures 1-3 it is preferable to align
the centerline of the ply 20 with the altitude of triangles 2, 4 to minimize overall
height requirements in the deposition chute 12, the lateral positioning of the ply
20 may be altered as desired relative to the apex of the triangle and will maintain
the selected position until manually repositioned. This is due to the fact that the
laterally imposed forces introduced on the ply by the illustrated system remain in
total balance with one another as the ply is tracked through the folding board. Thus,
there is nothing to disturb the equilibrium established once the desired position
of the web relative to the apex of the triangle or triangles has been established.
1. A continuous, in-line method for forming airlaid fibrous fluff web provided with
a substantially planar fiber-impervious internal reinforcing ply whose width is substantially
coextensive with that of said web characterised in that it comprises the steps of:
(a) continuously feeding said substantially planar reinforcing ply (20) in a first
direction in a first plane;
(b) introducing said moving reinforcing ply into a single fiber deposition zone in
which is disposed a foraminous support surface (11) moving in said first direction
while the ply is oriented so that the direction of fiber flow is substantially parallel
to the width of said ply, to vacuum form on said support surface, a first portion
(21) of said airlaid fibrous fluff web;
(c) guiding said moving reinforcing ply into contact with a first equal length leg
portion (58) of the trailing surface of a planar isosceles right angled triangle (52),
said first equal length leg portion being oriented perpendicular to said first direction
of travel of said ply (20);
(d) wrapping said moving reinforcing ply about opposite surfaces of said planar right
angled triangle (52) by passing said ply about the hypotenuse thereof;
(e) restoring said moving ply to said first direction of travel by passing said moving
ply about the second equal length leg portion (56) of said triangle (52), thereby
causing said ply to assume a planar condition in a second plane perpendicular to said
first plane, said ply being positioned with its lowermost surface immediately adjacent
said first airlaid fibrous fluff web portion (21);
(f) exposing the uppermost surface of said moving reinforcing ply to said fiber deposition
zone while in a planar condition to vacuum form a second portion (22) of said airlaid
fibrous fluff web adjacent the uppermost surface of said reinforcing ply (20); and
(g) removing said ply and said airlaid web portions from said fiber deposition zone.
2. A method according to Claim 1 characterised in that said planar isosceles right
angled triangle (52) is located in a plane perpendicular to said first direction of
travel of said substantially planar reinforcing ply and said ply is abruptly restored
to said first direction of travel prior to its exit from said fiber deposition zone.
3. A method according to either one of Claims 1 and 2 characterised in that the relative
thickness of the first and second airlaid fibrous fluff web portions is controlled
by adjusting the machine direction position of said isosceles right angled triangle
within said fiber deposition zone.
4. A method according to any one of Claims 1 to 3 characterised in that a greater
level of suction is applied to vacuum form the second airlaid fibrous fluff web portion
(22), than that applied to vacuum form the first air laid fibrous fluff web portion
(21), to offset the added resistance to airflow created by the reinforcing ply (21)
and the first fibrous fluff web portion (21 ).
5. A method according to any one of Claims 1 to 4 characterised in that the first
air laid fibrous fluff web portion (21) is vacuum formed directly over a second continuously
moving tissue ply (23) having a width at least as great as that of said internal reinforcing
ply (21), and in that a third continuously moving tissue ply (24) is applied directly
over the uppermost surface of the second airlaid fibrous fluff web portion (22) upon
exit thereof from said fiber deposition zone.
6. A method according to Claim 5 characterised in that said second and third tissue
plies (23, 24) have a width greater than that of said internal reinforcing ply (21)
and the lateral edges of said second and third tissue plies are secured together by
folding upon one another to form a continuous tissue envelope about the internal reinforcing
ply and the first and second airlaid fibrous fluff web portions (21,22).
7. A method according to Claim 6 characterised in that absorbent pad segments of predetermined
length are cut from said continuous tissue envelope and thereafter secured intermediate
a moisture-impervious backsheet and a moisture-pervious topsheet which are secured
in superposed relation to one another, thereby forming a disposable absorbent bandage.
8. An in-line apparatus for the continuous manufacture of an airlaid fibrous fluff
web provided with a substantially planar internal fiber impervious reinforcing ply
that is substantially coextensive with the width of said web, said apparatus being
characterised in that it comprises;
(a) a source of fibrous material in discrete fiber form
(b) a single fiber deposition chamber (12) into which said fibers are fed continuously
from said source;
(c) a continuously moving foraminous support member (11) passing through said deposition
chamber (12) in a plane substantially perpendicular to the direction of fiber flow;
(d) suction means (25, 26, 27) located adjacent the surface of said foraminous support
member (11) opposite said fiber source;
(e) means (57) for introducing said reinforcing ply (21) to said deposition chamber
in a first direction identical to that of said foraminous support member while said
ply is oriented in a first plane such that its width is substantially parallel to
the direction of fiber flow within said chamber to facilitate vacuum forming the portion
of said airlaid fibrous fluff web on said foraminous support member;
(f) Right-angled isosceles triangular guide means (52), 56, 58) extending perpendicular
to said first direction of travel within said fiber deposition chamber (12) for abruptly
reorienting said reinforcing ply to a second plane perpendicular to said first plane
while restoring said ply to said first direction of travel, thereby to contact the
lowermost surface thereof with said airlaid fibrous- fluff web and to facilitate vacuum
forming the portion of said airlaid fibrous fluff web adjacent the uppermost surface
of said reinforcing ply; and
(g) means for removing said ply and said airlaid web portions from said fiber deposition
chamber.
9. The apparatus of Claim 8, characterised in that the position of said triangular
guide means (52) is adjustable in the machine direction within the fiber deposition
chamber to vary the relative thickness of the first and second airlaid fibrous fluff
web portions.
10. The apparatus of either one of Claims 8 and 9 characterised in that said right
angled isosceles triangular guide means (52) is planar, with one of its equal length
leg portions (58) oriented perpendicular to said first direction of travel of said
reinforcing ply <21) and the other of its equal length leg portions (56) in a second
plane perpendicular to said first plane, said second plane being parallel to the plane
of said foraminous support member (11). ).
11. The apparatus of any one of Claims 8 to 10 wherein the suction means (25) located
adjacent the surface of said foraminous support member is comprised of a vacuum chamber
having a length at least equal to that of said fiber deposition chamber, said vacuum
chamber having an internal partition member (19) oriented perpendicular to the direction
of travel of said ply, said partition member being adjustable in the machine direction
to facilitate alignment thereof with said triangular guide means within said chamber
and thereby facilitate the application of a higher level of suction during formation
of the second airlaid fibrous fluff web portion.
12. The apparatus of any one of Claims 8 to 11 further including means for feeding
a second tissue ply (23) having a width at least as great as said reinforcing ply
into superposed relation with said foraminous support member prior to entry thereof
into said fiber deposition chamber (12) and means for feeding a third tissue ply (24)
having a width at least as great as said reinforcing ply (21) into superposed relation
with the uppermost surface of said uppermost airlaid fibrous fluff web portion (22)
upon exit thereof from said fiber deposition chamber (12).
13. A continuous, in-line method for forming an airlaid fiber impervious fibrous fluff
web provided with a substantially planar internal reinforcing ply that is substantially
coextensive with the width of said web characterised in that it comprises the steps
of:
(a) continuously feeding said substantially planar reinforcing ply (20) in a first
direction in a first plane;
(b) guiding said moving reinforcing ply about a first direction changing means (5)
and into contact with the leading surface of a first planar isosceles right angled
triangle (2) said triangle having its altitude (40) oriented perpendicular to said
first direction of travel of said ply;
(c) wrapping said moving reinforcing ply about opposite surfaces of said first planar
triangle;
(d) restoring said moving ply to its first direction of travel by directing said ply
about the apex of said first triangle while maintaining the lateral edge portions
of said moving ply in contact with the leading and trailing surfaces of said first
triangle, thereby causing said ply to fold about itself in a second plane perpendicular
to said first plane;
(e) introducing said moving reinforcing ply to a single fiber deposition zone in which
is disposed a foraminous support surface (11) moving in said first direction while
the ply is in a folded configuration, to vacuum form on said support surface, a first
portion (21) of said airlaid fibrous fluff web;
(f) wrapping said moving reinforcing ply about opposite surfaces of a second isosceles
triangle (4) identical to and longitudinally aligned with said first triangle (2)
and having its altitude (41) oriented perpendicular to said first direction of travel
such that the lateral edges of said moving ply are guided on opposite sides of the
apex of said second triangle as said moving ply is directed about the apex thereof,
the lateral edges of said moving ply being maintained in contact with the leading
and trailing surfaces of said second triangle, thereby restoring said ply to a planar
condition;
(g) directing said moving reinforcing ply about a second direction changing means
(6) to restore it to said first direction of travel and to bring the lowermost surface
thereof into contact with the first airlaid fibrous fluff portion (21);
(h) exposing the uppermost surface of said moving reinforcing ply to said fiber deposition
zone while in a planar condition to vacuum form a second portion (22) of said airlaid
fibrous fluff web adjacent the uppermost surface of said reinforcing ply; and
(i) removing said ply and said airlaid fibrous fluff portions from fiber deposition
zone.
14. A method according to Claim 13 characterised in that the centerline of said moving
reinforcing ply (20) is caused to coincide with the altitudes (40, 41) of said first
and said second isosceles triangles as said ply is drawn across the surfaces thereof,
thereby causing said ply to assume an inverted U-configuration about its centerline
as it moves intermediate said first and said second triangles.
15. A method according to either one of Claims 13 and 14 wherein said first and second
isosceles triangles are in parallel planes which are perpendicular to said first direction
of travel of said substantially planar reinforcing ply.
16. A method according to any one of Claims 13 to 15 characterised in that the relative
thickness of the first and second airlaid fibrous fluff web portions (21, 22) is controlled
by adjusting the machine direction position of said second isosceles triangle (4)
within said fiber deposition zone.
17. A method according to any one of Claims 13 to 16 characterised in that a greater
level of suction is applied to vacuum form the second airlaid fibrous fluff web portion
(22), than is applied to vacuum form the first airlaid fibrous fluff web portion (21)
to offset the added resistance to airflow created by said ply (20) and said first
airlaid fibrous fluff web portion (21 ).
18. A method according to any one of Claims 13 to 17 characterised in that the first
portion (21) of said airlaid fibrous fluff web is formed directly on the surface of
a second moving tissue ply (23) having a width at least as great as said reinforcing
ply; and after said plies and said first and second airlaid web portions are removed
from said fiber deposition zone a third tissue ply (24), having a width at least as
great as said reinforcing ply, is superposed upon the second portion of said airlaid
web (22).
19. A method according to Claim 18 wherein said second and third tissue plies have
a width greater than that of said internal reinforcing ply and the lateral edges of
said second and third plies are secured together by folding upon one another to form
a continuous tissue envelope about the internal reinforcing ply and the first and
second airlaid fibrous fluff web portions.
20. A method according to Claim 19 wherein absorbent pad segments of predetermined
length are cut from said continuous tissue envelope and thereafter secured intermediate
a moisture-impervious backsheet and a moisture-pervious topsheet which are secured
in superposed relation to one another, thereby forming a disposable absorbent bandage.
21. An in-line apparatus for the continuous manufacture of an airlaid fibrous fluff
web provided with a substantially planar internal fiber-impervious reinforcing ply
that is substantially co-extensive with the width of said web, said apparatus being
characterised in that it comprises:
(a) a source of fibrous material in discrete fiber form;
(b) a single fiber deposition chamber (12) into which said fibers are fed continuously
from said source;
(c) a continuously moving foraminous support member (11) passing through said deposition
chamber in a plane substantially perpendicular to the direction of fiber flow;
(d) suction means (25) located adjacent the surface of said foraminous support member
(11) opposite said fiber source:
(e) means for continuously feeding said reinforcing ply in the same direction as said
foraminous support member while oriented in a first plane parallel to that of said
foraminous support member;
(f) first right-angled isosceles triangular guide means (2, 5), extending in a direction
perpendicular to said direction of travel for abruptly causing said reinforcing ply
to fold about itself in a second plane perpendicular to said first plane;
(g) means (3, 7, 8) for introducing said reinforcing ply to said fiber deposition
chamber while in a folded configuration to facilitate vacuum forming a first airlaid
fibrous fluff web portion adjacent the foraminous support member;
(h) second right-angled isosceles triangular guide means extending perpendicular to
the direction of travel (4, 6) of said reinforcing ply within said fiber deposition
chamber (12) for abruptly reorienting said ply from a folded configuration to a planar
configuration in said first plane while restoring said ply to said first direction
of travel to bring the lowermost surface of said ply into contact with said first
airlaid fibrous fluff web portion and to facilitate vacuum forming a second portion
of said airlaid fibrous fluff web adjacent the uppermost surface of said reinforcing
ply; and
(i) means for removing said ply and said airlaid web portions from said fiber deposition
chamber.
22. The apparatus of Claim 21, characterised in that said first and second guide means
(2, 4) comprise identical planar triangular bodies, (42, 43, 44, 45, 46, 47) maintained
in longitudinally aligned parallel relationship by a planar member (3) connecting
their respective attitudes (40, 41).
23. The apparatus of Claims 22 characterised in that the planar isosceles triangles
(2, 4) and said connecting planar member (3) are adjustable as a unit (1) in the machine
direction to vary the relative thickness of the first and second air laid fibrous
fluff web portions.
24. The apparatus of any one of Claims 21-23 wherein the suction means (25) located
adjacent the surface of said foraminous support member is comprised of a vacuum chamber
having a length at least equal to that of said fiber deposition chamber, said vacuum
chamber having an internal partition member (19) oriented perpendicular to the direction
of travel of said ply, said partition member being adjustable in the machine direction
to facilitate alignment thereof with said second triangular guide means (4) within
said chamber and thereby facilitate the application of a higher level of suction during
formation of the second airlaid fibrous fluff web portion.
1. Kontinuierliches Durchlaufverfahren zur Bildung einer luftabgelegten Faserflaumbahn,
die mit einer praktisch planaren, faserundurchlässigen inneren Verstärkungslage versehen
ist, deren Breite praktisch gleich derjenigen der Bahn ist, dadurch gekennzeichnet,
dass es die Schritte umfasst:
(a) kontinuierliches Einführen der praktisch planaren Verstärkungslage (20) in einer
ersten Richtung in eine erste Ebene;
(b) Einführen der laufenden Verstärkungslage in eine Einzelfaserablagezone, in welcher
eine perforierte Trägerfläche (11) angeordnet ist, die sich in der ersten Richtung
bewegt, während die Lage so orientiert ist, dass der Faserstrom praktisch parallel
zur Breite der Lage gerichtet ist, um auf der Trägerfläche durch Saugformung einen
ersten Teil (21) der luftabgelegten Faserflaumbahn zu bilden;
(c) Führen der laüfenden Verstärkungslage in Kontakt mit einem ersten gleichlängigen
Schenkelteil (58) der hinteren Oberfläche eines planaren gleichschenkligen rechtwinkligen
Dreiecks (52), wobei der erste gleichlängige Schenkelteil senkrecht zur ersten Laufrichtung
der Lage (20) orientiert ist;
(d) Umlegen der laufenden Verstärkungslage um einander gegenüberliegende Oberflächen
des planaren rechtwinkligen Dreiecks (52) durch Führen der Lage um die Hypotenuse
des Dreiecks;
(e) Rückführen der laufenden Lage in die erste Bewegungsrichtung durch Führung der
laufenden Lage um den zweiten gleichlängigen Schenkelteil (56) des Dreiecks (52),
um dadurch zu bewirken, dass die Lage einen planen Zustand in einer zweiten Ebene
senkrecht zur ersten Ebene annimmt, wobei die Lage mit ihrer unteren Fläche unmittelbar
auf dem ersten luftabgelegten Faserflaumbahnteil (21) liegt;
(f) Exponieren der oberen Fläche der laufenden Verstärkungslage in planarem Zustand
in der Faserablagezone, um einen zweiten Teil (22) der luftabgelegten Faserflaumbahn
auf der oberen Fläche der Verstärkungslage (20) durch Saugformung zu bilden, und
(g) Abführen der Lage und der luftabgelegten Bahnteile aus der Faserablagezone.
2. Verfahren nach Patentanspruch 1, dadurch gekennzeichnet, dass das planare gleichschenklige
rechtwinklige Dreieck (52) in einer Ebene senkrecht zur ersten Laufrichtung der praktisch
planaren Verstärkungslage angeordnet ist und dass die Lage vor ihrer Abführung aus
der Faserablagezone jäh in die erste Laufrichtung zurückgeführt wird.
3. Verfahren nach einem der Patentansprüche 1 oder 2, dadurch gekennzeichnet, dass
die relativen Dicken der ersten und zweiten luftabgelegten Faserflaumbahnteile durch
Einstellen der Maschinenrichtungsstellung des gleichschenkligen rechtwinkligen Dreiecks
in der Faserablagezone geregelt werden.
4. Verfahren nach einem der Patentansprüche 1-3, dadurch gekennzeichnet, dass zur
Saugformung des zweiten luftabgelegten Faserflaumbahnteils (22) ein stärkerer Sog
angewendet wird, als zur Saugformung des ersten luftabgelegten Faserflaumteils (21),
um den zusätzlichen Luftströmungswiderstand auszugleichen, der durch die Verstärkungslage
(21) und den ersten Faserflaumbahnteil (21) verursacht wird.
5. Verfahren nach einem der Patentansprüche 1-4, dadurch gekennzeichnet, dass der
erste luftabgelegte Faserflaumbahnteil (21) durch Saugformung direkt auf einer zweiten
kontinuierlich laufenden Papiertuchlage (23) gebildet wird, die eine mindestens ebenso
grosse Breite wie die innere Verstärkungslage (21) hat, und dass eine dritte kontinuierlich
laufende Papiertuchlage (24) direkt auf die obere Fläche des zweiten luftabgelegten
Faserflaumbahnteils (22) bei dessen Abführung aus der Faserablagezone aufgebracht
wird.
6. Verfahren nach Patentanspruch 5, dadurch gekennzeichnet, das die zweite und dritte
Papiertuchlage (23, 24) grössere Breiten haben, als die innere Verstärkungslage (21),
und dass die Seitenkanten der zweiten und dritten Papiertuchlage durch Aufeinanderfaltung
miteinander verbunden werden, um eine fortlaufende Papiertuchhülle um die Innenverstärkungslage
und den ersten und den zweiten luftabgelegten Faserflaumbahnteil (21, 22) zu bilden.
7. Verfahren nach Patentanspruch 6, dadurch gekennzeichnet, dass aus der fortlaufenden
Papiertuchhülle saugfähige Polstersegmente vorbestimmter Länge geschnitten und dann
zur Erzeugung einer saugfähigen Wegwerfbandage zwischen einem feuchtigkeitsundurchlässigen
Rückblatt und einem feuchtigkeitsdurchlässigen Vorderblatt übereinanderliegend befestigt
werden.
8. Durchlaufvorrichtung zur kontinuierlichen Herstellung einer luftabgelegten Faserflaumbahn,
die mit einer praktisch planaren inneren faserund
-urchlässigen Verstärkungslage versehen ist, die praktisch gleich breit wie die Bahn
ist, welche Vorrichtung gekennzeichnet ist durch
(a) eine Quelle für Fasermaterial in Form von Einzelfasern,
(b) eine Einzelfaserablagekammer (12), in welche die Fasern von der Quelle kontinuierlich
eingespeist werden;
(c) einen kontinuierlich laufenden perforierten Träger (11), der durch die Ablagekammer
(12) in einer Ebene praktisch senkrecht zur Richtung des Faserstroms läuft;
(d) eine Saugeinrichtung (25, 26, 27), die benachbart zur Oberfläche des perforierten
Trägers (11) entgegengesetzt zur Faserquelle angeordnet ist;
(e) eine Einrichtung (57) zur Einführung der Verstärkungslage (21) in die Ablagekammer
in einer ersten Richtung gleich derjenigen des perforierten Trägers, während die Lage
in einer ersten Ebene derart orientiert ist, dass ihre Breite praktisch parallel zur
Richtung des Faserstroms in der Kammer liegt, um die Saugformung des Teils der luftabgelegten
Faserflaumbahn auf dem perforierten Träger zu erleichtern,
(f) rechteckig - gleichschenklig - dreieckige Führungen (52, 56, 58), welche sich
senkrecht zur ersten Laufrichtung in der Faserab!agekammer"(12) erstrecken, um die
Verstärkungslage jäh in eine zweite Ebene umzulenken, welche senkrecht zur ersten
Ebene liegt, während die Lage in die erste Laufrichtung zurückgeführt wird, um dadurch
ihre untere Fläche mit der luftabgelegten Faserflaumbahn in Kontakt zu bringen und
die Saugformung des Teils der luftabgelegten Faserflaumbahn auf der oberen Fläche
der Verstärkungslage zu erleichtern, und
(g) eine Einrichtung zum Abführen der Lage und der luftabgelegten Bahnteile aus der
Faserablagekammer.
9. Vorrichtung nach Patentanspruch 8, dadurch gekennzeichnet, dass die Stellung der
dreieckigen Führung (52) in der Faserablagekammer in Maschinenrichtung einstellbar
ist, um die relativen Dicken der ersten und der zweiten luftabgelegten Faserflaumbahnteile
zu verändern.
10. Vorrichtung nach Patentanspruch 8 oder 9, dadurch gekennzeichnet, dass die rechtwinklig-gleichschenklig-dreieckige
Führung (52) planar ist, wobei einer ihrer gleichlängigen Schenkelteile (58) senkrecht
zur ersten Laufrichtung der Verstärkungslage (21) und der anderer ihrer gleichlängigen
Schenkelteile (56) in einer zweiter Ebene senkrecht zur ersten Ebene orientiert ist,
wobei die zweite Ebeneparallel zur Ebene des perforierten Trägerteils (11) liegt.
11. Vorrichtung nach einem der Patentansprüche 8-10, bei welcher die Saugeinrichtung
(25), die angrenzend an die Oberfläche des mit Durchbrechungen versehenen Trägers
angeordnet ist, eine Vakuumkammer besitzt, deren Länge mindestens gleich derjenigen
der Faserablagekammer ist, wobei die Vakuumkammer eine innere Trennwand (19) besitzt,
die senkrecht zur Laufrichtung der Lage orientiert und in Maschinenrichtung einstellbar
ist, um ihre Ausrichtung mit der dreieckigen Führung in der Kammer zu erleichtern
und dadurch die Anwendung eines stärkeren Soges während der Bildung des zweiten luftabgelegten
Faserflaumbahnteils zu erleichtern.
12. Vorrichtung nach einem der Patentansprüche 8-11 mit einer Einrichtung zur Einführung
einer zweiten Lage (23) aus Papiertuch, die eine mindestens ebenso grosse Breite wie
die Verstärkungslage hat aufliegend auf dem perforierten Träger vor dessen Eintritt
in die Faserablagekammer (12), und mit einer Einrichtung zur Einführung einer dritten
Lage (24) aus Papiertuch, die eine mindestens ebensogrosse Breite wie die Verstärkungslage
(21) hat, aufliegend auf der oberen Fläche des oberen luftabgelegten Faserflaumbahnteils
(22) bei dessen Auführung aus der Faserablagekammer (12).
13. Kontinuierliches Durchlaufverfahren zur Bildung einer luftabgelegten faserundurchlässigen
Faserflaumbahn, die mit einer praktisch planaren inneren Verstärkungslage versehen
ist, die praktisch die gleiche Breite wie die Bahn hat, dadurch gekennzeichnet, dass
das Verfahren folgende Schritte umfasst:
(a) kontinuierliches Einführen der praktisch planaren Verstärkungslage (20) in einer
ersten Richtung in eine erste Ebene;
(b) Führen der laufenden Verstärkungslage um ein erstes Richtungsänderungsmittel (5)
und in Kontakt mit der vorderen Oberfläche eines ersten planaren gleichschenkligen
rechtwinkligen Dreiecks (2), dessen Höhe (40) senkrecht zur ersten Laufrichtung der
Lage orientiertist;
(c) Umlenken der laufenden Verstärkungslage um einander entgegengesetzte Oberflächen
des ersten planaren Dreiecks;
(d) Rückführung der laufenden Lage in deren erste Laufrichtung durch Führen der Lage
um die Spitze des ersten Dreiecks, während die Seitenkantenteile der laufenden Lage
in Kontakt mit den vorderen und hinteren Oberflächen der ersten Dreiecks gehalten
werden, wodurch bewirkt wird, dass die Lage in einer zweiten Ebene senkrecht zur ersten
Ebene um sich selbst gefaltet wird;
(e) Einführen der laufenden Verstärkungslage in eine Einzelfaserablagezone, in welcher
eine perforierte Trägerfläche (11) angeordnet ist, die sich in der ersten Richtung
bewegt, während die Lage sich in einem gefalteten Zustand befindet, um auf der Trägerfläche
einen ersten.Teil (21) der luftabgelegten Faserflaumbahn durch Saugformung zu bilden;
(f) Umlegen der laufenden Verstärkungslage um einander entgegengesetzte Oberflächen
eines zweiten gleichschenkligen Dreiecks (4), das identisch mit dem ersten Dreieck
(2) und in Längsrichtung mit diesem ausgerichtet ist, und dessen Höhe (41) senkrecht
zur ersten Laufrichtung orientiert ist, so dass die Seitenkanten der laufenden Lage
an einander gegenüberliegenden Seiten der Spitze des zweiten Dreiecks geführt werden,
wenn die laufende Lage um dessen Spitze geführt wird, wobei die Seitenkanten der laufenden
Bahn in Kontakt mit den vorderen und hinteren Oberflächen des zweiten Dreiecks gehalten
werden, wodurch die Lage wieder in einen planaren Zustand zurückgeführt wird;
(g) Führen der laufenden Verstärkungslage um ein zweites Richtungsänderungsmittel
(6), um sie in die erste Laufrichtung zurückzuführen und um ihre untere Fläche mit
dem ersten luftabgelegten Faserflaumbahnteil (21) in Kontakt zu bringen;
(h) Exponieren der oberen Fläche der laufenden Verstärkungslage in planarem Zustand
in der Faserablagezone zur Saugformung eines zweiten Teils (22) der luftabgelegten
Faserflaumbahn aur der oberen Fläche der Verstärkungslage, und
(i) Abführen der Lage und der luftabgelegten Faserflaumbahnteile aus der Faserablagezone.
14. Verfahren nach Patentanspruch 13, dadurch gekennzeichnet, dass die Mittellinie
der laufenden Verstärkungslage (20) übereinstimmend mit den Höhen (40), 41) des ersten
und des zweiten gleichschenkligen Dreiecks geführt wird, wenn die Lage über deren
Oberflächen gezogen wird, wodurch bewirkt wird, dass die Lage bei ihrer Bewegung zwischen
dem ersten und dem zweiten Dreieck eine umgekehrte U-Form um ihre Mittellinie annimmt.
15. Verfahren nach einem der Patentansprüche 13 oder 14, worin das erste und das zweite
gleichschenklige Dreieck in parallelen Ebenen senkrecht zur ersten Laufrichtung der
praktisch planaren Verstärkungslage liegen.
16. Verfahren nach einem der Patentansprüche 13-15, dadurch gekennzeichnet, dass die
relativen Dicken des ersten und des zweiten luftabgelegten Faserflaumbahnteils (21,
22) durch Einstellen der Maschinenrichtungsstellung des zweiten gleichschenkligen
Dreiecks (4) in der Faserablagezone gesteuert werden.
17. Verfahren nach einem der Patentansprüche 13-16, dadurch gekennzeichnet, dass zum
Saugformen des zweiten luftabgelegten Faserflaumbahnteils (22) ein stärkerer Sog als
beim Saugformen des ersten luftabgelegten Faserflaumbahnteils (21) angewendet wird,
um den zusätzlichen Luftströmungswiderstand auszugleichen, der durch die Lage (20)
und den ersten luftabgelegten Faserflaumbahnteil (21) erzeugt wird.
18. Verfahren nach einem der Patentansprüche 13-17, dadurch gekennzeichnet, dass der
erste Teil (21) der luftabgelegten Faserflaumbahn direkt auf der Oberfläche einer
zweiten laufenden Papiertuchlage (23) gebildet wird, die eine mindestens ebensogrosse
Breite wie die Verstärkungslage hat; und wobei nach dem Abführen der Lagen und der
ersten und zweiten luftabgelegten Bahnteile aus der Faserablagezone eine dritte Papiertuchlage
(24) mit einer mindestens ebensogrossen Breite wie die Verstärkungslage auf den zweiten
Teil der luftabgelegten Bahn (22) aufgelegt wird.
19. Verfahren nach Patentanspruch 18, dadurch gekennzeichnet, dass die zweiten und
dritten Papiertuchlagen grössere Breiten haben als die innere Verstärkungslage, und
dass die Seitenkanten der zweiten und dritten Lagen durch Aufeinanderfalten miteinander
verbunden werden, um eine kontinuierliche Papiertuchhülle um die innere Verstärkungslage
und die ersten und zweiten luftabgelegten Faserflaumbahnteile zu bilden.
20. Verfahren nach Patentanspruch 19, bei welchem aus der kontinuierlichen Papiertuchhülle
saugfähige Polstersegmente vorbestimmter Länge geschnitten und danach zwischen einem
feuchtigkeitsundurchlässigen Rückblatt und einem feuchtigkeitsdurchlässigen Vorderblatt
übereinanderliegend befestigt werden, um eine saugfähige Wegwerfbandage herzustellen.
21. Durchlaufvorrichtung zur kontinuierlichen Herstellung einer luftabgelegten Faserflaumbahn,
die mit einer praktisch planaren inneren faserundurchlässigen Verstärkungslage versehen
ist, die praktisch gleich breit wie die Bahn ist, welche Vorrichtung gekennzeichnet
ist durch:
(a) eine Quelle für faseriges Material in Form von Einzelfasern;
(b) eine Einzelfaserablagekammer (12), in welche die Fasern kontinuierlich von der
Quelle eingespeist werden;
(c) einen kontinuierlich bewegten perforierten Träger (11), der in einer Ebene praktisch
senkrecht zur Richtung des Faserstroms durch die Ablagekammer läuft;
(d) eine Saugeinrichtung (25), die benachbart zur Oberfläche des perforierten Trägers
(11) und gegenüberliegend zur Faserquelle angeordnet ist;
(e) eine Einrichtung zur kontinuierlichen Einführung der Verstärkungslage in gleicher
Richtung wie der perforierte Träger unter Orientierung in einer ersten Ebene parallel
zu derjenigen des perforierten Trägers;
(f) eine erste rechtwinklig-gleichschenkligdreieckige Führung (2, 5), die sich senkrecht
zur Laufrichtung erstreckt, um eine jähe Umfaltung der Verstärkungslage um sich selbst
und in eine zweite Ebene senkrecht zur ersten Ebene zu bewirken;
(g) eine Einrichtung (3, 7, 8) zur Einführung der Verstärkungslage in die Faserablagekammer
in gefalteter Form zur Erleichterung der Saugformung eines ersten luftabgelegten Faserflaumbahnteils
auf dem perforierten Träger;
(h) eine zweite rechtwinklig-gleichschenkligdreieckige Führung, die sich senkrecht
zur Laufrichtung (4, 6) der Verstärkungslage in der Faserablagekammer (12) erstreckt,
um die Lage jäh aus einer umgefalteten Form in eine planare Form in der ersten Ebene
umzuorientieren und die Lage wieder in die erste Laufrichtung zu führen, so dass die
untere Fläche der Lage mit dem ersten luftabgelegten Faserflaumbahnteil in Kontakt
kommt und die Saugformung eines zweiten Teils der luftabgelegten Faserflaumbahn auf
der oberen Fläche der Verstärkungslage erleichtert wird, und
(i) eine Einrichtung zum Abführen der Lage und der luftabgelegten Faserflaumbahnteile
aus der Faserablagekammer.
22. Vorrichtung nach Patentanspruch 21, dadurch gekennzeichnet, dass die erste und
zweite Führung (2, 4) identische planare dreieckige Körper (42, 43, 44, 45, 46, 47)
besitzen, die in Längsrichtung parallel ausgerichtet und durch einen planaren Teil
(3) an den jeweiligen Höhen (40, 41) miteinander verbunden sind.
23. Vorrichtung nach Patentanspruch 22, dadurch gekennzeichnet, dass die planaren
gleichschenkligen Dreiecke (2, 4) und der planare Verbindungsteil (3) als eine Einheit
(1) in der Maschinenrichtung einstellbar sind, um die relativen Dicken der ersten
und zweiten luftabgelegten Faserflaumbahnteile zu verändern.
24. Vorrichtung nach einem der Patentansprüche 21-23, wobei die Saugeinrichtung (25),
die benachbart zur Oberfläche des perforierten Trägers angeordnet ist, eine Vakuumkammer
besitzt, die eine mindestens ebensogrosse Länge wie die Faserablagekammer hat, wobei
die Vakuumkammer eine innere Trennwand (19) besitzt, die senkrecht zur Laufrichtung
der Lage steht und in Maschinenrichtung einstellbar ist, um ihre Ausrichtung mit der
zweiten dreieckigen Führung (4) in der Kammer zu erleichtern und dadurch das Anlegen
eines stärkeren Soges während der Bildung des zweiten luftabgelegten Faserflaumbahnteils
zu erleichtern.
1. Procédé continu en ligne pour la formation d'une nappe de duvet fibreux déposée
pneumatiquement, munie d'une couche intérieure de renforcement pratiquement plane,
imperméable aux fibres, dont la largeur est pratiquement égale à celle de la nappe,
caractérisé par les étapes suivantes:
(a) faire avancer en continu la couche de renforcement pratiquement plane (20) dans
une première direction dans un premier plan,
(b) introduire la couche de renforcement en mouvement dans une seule zone de dépôt
de fibres dans laquelle est disposée une surface de support perforée (11) se déplaçant
dans la première direction, tandis que la couche est orientée de telle sorte que la
direction d'écoulement des fibres soit pratiquement parallèle à la largeur de la couche,
pour former par dépression sur la surface de support une première partie (21) de la
nappe de duvet fibreux déposée pneumatiquement,
(c) guider la couche de renforcement en mouvement pour l'amener en contact avec un
premier des côtés égaux (58) de la surface postérieure d'un triangle rectangle isocèle
plan (52), ce premier côté étant orienté perpendiculairement à la première direction
de mouvement de la couche (20),
(d) enrouler la couche de renforcement en mouvement autour de surfaces opposées du
triangle rectangle plan (52) en faisant passer la couche autour de l'hypoténuse de
celui-ci,
(e) ramener la couche en mouvement dans la première direction de déplacement en faisant
passer la couche en mouvement autour du deuxième côtés égaux (56) du triangle (52)
de façon que la couche prenne une position plane dans un deuxième plan perpendiculaire
au premier plan, la couche étant dans une position où sa surface inférieure est immédiatement
adjacent à la prepremière partie de nappe de duvet fibreux (21) déposée pneumatiquement,
(f) exposer la surface supérieure de la couche de renforcement en mouvement à la zone
de dépôt de fibres pendant qu'elle est dans une position plane, pour former par dépression
une deuxième partie (22) de la nappe de duvet fibreux déposée pneumatiquement, au
voisinage de la surface supérieure de la couche de renforcement (20), et
(g) retirer de la zone de la zone de dépôt de fibres la couche et les parties de nappe
déposée pneumatiquement.
2. Procédé selon la revendication 1, caractérisé en ce que le triangle rectangle isocèle
plan (52) est siotué dans un plan perpendiculaire à la première direction de mouvement
de la couche de renforcement pratiquement plane et en ce que cette couche est ramenée
brusquement à la première direction de mouvement avant de sortir de la zone de dépôt
de fibres.
3. Procédé selon l'une des revendications 1 ou 2, caractérisé en ce que pour régler
l'épaisseur relative des première et deuxième parties de nappe de duvet fibreux déposée
pneumatiquement, en règle la position de direction de fabrication du triangle rectangle
isocèle au sein de la zone de dépôt de fibres.
4. Procédé selon l'une quelconque des revendications 1 à 3, caractérisé en ce que
l'on applique un niveau d'aspiration plus élevé pour former par dépression la deuxième
partie de nappe de duvet fibreux déposée pneumatiquement (22) que pour former par
dépression la première partie de nappe de duvet fibreux déposée pneumatiquement (21),
afin de compenser la résistance supplémentaire opposée à 1 écoulement d'air par la
couche de renforcement (20) et la première partie de nappe de duvet fibreux (21).
5. Procédé selon l'une quelconque des revendications 1 à 4, caractérise en ce que
l'on forme directement par dépression la première partie de nappe de duvet fibreux
déposée pneumatiquement (21) par dessus une deuxième couche de papier mousseline (23)
en mouvement continu, ayant une largeur au moins aussi grande que la couche de renforcement
intérieure (20) et en ce que l'on applique directement une troisième couche de papier
mousseline (24) en mouvement continu par dessus la surface supérieure de la deuxième
partie de nappe de duvet fibreux déposée pneumatiquement (22) lorsque celle-ci sort
de zone de dépôt de fibres.
6. Procédé selon la revendication 5, caractérisé en ce que les deuxième et troisième
couches de papier mousseline (23, 24) ont une largeur supérieure à celle de la couche
intérieur de renforcement (20) et que l'on fixe ensemble les bords latéraux des deuxième
et troisième couches de papier mousseline en les pliant l'un sur l'autre pour former
une enveloppe continue de papier mousseline autour de la couche de renforcement intérieure
et des première et deuxième parties de nappe de duvet fibreux déposée pneumatiquement
(21, 22).
7. Procédé selon la revendication 6, caractérisé en ce que l'on coupe dans l'enveloppe
continue de papier mousseline des segments de tampon absorbant de longueur prédéterminée
et qu'ensuite on les place entre une feuille de soutien imperméable à l'humidité et
une feuille supérieure perméable à l'humidité que l'on fixe en les superposant de
manière à former un bandage absorbant jetable.
8. Appareil en ligne pour la fabrication continue d'une nappe de duvet fibreux déposée
pneumatiquement, munie d'une couche intérieure de renforcement pratiquement plane,
imperméable aux fibres, dont la largeur est pratiquement égale à celle de la nappe,
appareil caractérisé en ce qu'il comprend:
(a) une source de matière fibreuse sous forme de fibres distinctes,
(b) une seule chambre de dépôt de fibres (12) à laquelle les fibres sont amenées continuellement
de la source,
(c) un élément support perforé (11) en mouvement continu passant à travers la chambre
de dépôt (12), dans un plan pratiquement perpendiculaire à la direction d'écoulement
des fibres,
(d) des moyens d'aspiration (25, 26, 27) situés au voisinage de la surface de l'élément
support perforé (11), à l'opposé de la source de fibres,
(e) des moyens (57) permettant d'introduire la couche de renforcement (20) dans la
chambre de dépôt dans une première direction identique à celle de l'élément support
perforé, tandis que la couche est orientée dans un premier plan de telle sorte que
sa largeur soit pratiquement parallèle à la direction d'écoulement des fibres à l'intérieur
de la chambre, pour faciliter la formation par dépression de la partie de la nappe
de duvet fibreux déposée pneumatiquement su l'élément support perforé,
(f) des moyens de guidage en forme de triangle rectangle isocèle (52, 56, 58) placés
perpendiculairement à la première direction de mouvement à l'intérieur de la chambre
de dépôt de fibres (12) de manière à réorienter brusquement la couche de reforcement
dans un deuxième plan perpendiculaire au premier plan, tout en ramenant la couche
dans la première direction de mouvement de manière à mettre en contact sa surface
inférieure avec la nappe de duvet fibreux déposée pneumatiquement et à faciliter la
formation par dépression de la partie de la nappe de duvet fibreux déposée pneumatiquement
qui est adjacente à la surface supérieure de la couche de renforcement, et
(g) des moyens permettant de retirer de la chambre de dépôt de fibres la couche et
les parties de nappe déposée pneumatiquement.
9. Appareil selon la revendication 8, caractérisé en ce que la position des moyens
de guidage triangulaires (52) est réglable dans la direction de fabrication, à l'intérieur
de la chambre de dépôt de fibres, pour faire varier l'épaisseur relative des première
et deuxième parties de nappe de duvet fibreux déposée pneumatiquement.
10. Appareil selon l'une des revendications 8 ou 9, caractérisé en ce que les moyens
de guidage (52) en forme de triangle rectangle isocèle sont plans, l'un des côtés
égaux (58) étant orienté perpendiculairement à la première direction de mouvement
de la couche de renforcement (20) et la'autre des côtés égaux (56) dans un deuxième
plan perpendiculaire au premier plan, le deuxième plan étant parallèle au plan de
l'élément support perforé (11).
11. Appareil selon l'une quelconque des revendications 8 à 10, caractérisé en ce que
les moyens d'aspiration (25) situés auprès de la surface de l'élément support perforé
sont formés d'une chambre à vide ayant une longueur au moins égale à celle de la chambre
de dépôt de fibres et présentant une cloison intérieure (19) orientée perpendiculairement
à la direction de mouvement de la couche, cette cloison étant réglable dans la direction
de fabrication de manière à faciliter son alignement sur les moyens de guidage triangulaires
à l'intérieur de la chambre et à faciliter ainsi l'application d'un niveau d'aspiration
plus élevé pendant la formation de la deuxième partie de nappe de duvet fibreux déposée
pneumatiquement.
12. Appareil selon l'une quelconque des revendications 8 à 11, caractérisé en ce qu'il
comprend en outre des moyens permettant de faire avancer une deuxième couche de papier
mousseline (23) ayant une largeur au moins égale à celle de la couche de renforcement,
en la superposant au support perforé avant son entrée dans la chambre de dépôt de
fibres (12) et des moyens permettant de faire avancer une troisième couche de papier
mousseline (24) ayant une largeur au moins égale à celle de la couche de renforcement
(20) en la superposant à la surface supérieure de la partie supérieure de nappe de
duvet fibreux déposée pneumatiquement (22) à sa sortie de la chambre de dépôt de fibres
(12).
13. Procédé continu en ligne pour la formation d'une nappe de duvet fibreux déposée
pneumatiquement, munie d'une couche intérieure de renforcement pratiquement plane,
imperméable aux fibres, dont la largeur est pratiquement égale à celle de la nappe,
caractérisé par les étapes suivantes:
(a) faire avancer en continu la couche de renforcement pratiquement plane (20) dans
une première direction dans un premier plan,
(b) guider la couche de renforcement en mouvement autour d'un premier moyen de changement
de direction (5) pour l'amener en contact avec la surface antérieure d'un premier
triangle rectangle isocèle plan (2) dont la hauteur (40) est orientée perpendiculairement
à la première direction de mouvement de la couche,
(c) enrouler la couche de renforcement en mouvement autour de surfaces opposées du
premier triangle plan,
(d) ramener la couche en mouvement dans sa première direction de mouvement en dirigeant
la couche autour du sommet du premier triangle tout en maintenant les parties marginales
latérales de la couche en mouvement en contact avec les surfaces antérieure et postérieure
du premier triangle, de sorte que la couche se plie sur elle-même dans un deuxième
plan perpendiculaire au premier plan,
(e) introduire la couche de renforcement en mouvement dans une seule zone de dépôt
de fibres dans laquelle est disposée une surface de support perforée (11) se déplaçant
dans la première direction, tandis que la couche est dans une configuration pliée,
de manière à former par dépression sur la surface de support une première partie (21)
de la nappe de duvet fibreux déposée pneumatiquement,
(f) enrouler la couche de renforcement en mouvement autour de surfaces opposées .
d'un deuxième triangle isocèle (4) identique au premier triangle (2), aligné longitudinalement
sur celui-ci et dont la hauteur (41) est orientée perpendiculairement à la première
direction de mouvement de sorte que les bords latéraux de la couche en mouvement soient
guidés sur des côtés opposés du sommet du deuxième triangle à mesure que la couche.
en mouvement est dirigée autour du sommet de celui-ci, les bords latéraux de la couche
en mouvement étant maintenus en contact avec les surfaces antérieure et postérieure
du deuxième triangle de manière à ramener la couche à une position plane,
(g) diriger la couche de renforcement en mouvement autour d'un deuxième moyen de changement
de direction (6) pour la ramener dans la première direction de mouvement et pour amener
sa surface inférieure en contact avec la première partie (21 ) de duvet fibreux déposée
pneumatiquement;
(h) exposer la surface supérieure de la couche de renforcement en mouvement à la zone
de dépôt de fibres pendant qu'elle est dans une condition plane de manière à former
par dépression une deuxième partie (22) de la nappe de duvet fibreux déposée pneumatiquement
au voisinage de la surface supérieure de la couche de renforcement, et
(i) retirer de la zone de dépôt de fibres la couche et les parties de duvet fibreux
déposée pneumatiquement.
14. Procédé selon la revendication 13, caractérisé en ce que l'on fait coïncider la
ligne médiane de la couche de renforcement en mouvement (20) avec les hauteurs (40,
41) des premier et deuxième triangles isocèles à mesure que l'on tire la couche en
travers des surfaces de ceux-ci, ce qui fait que la couche prend une configuration
en U renversé autour de sa ligne médiane à mesure qu'elle se déplace entre les premier
et deuxième triangles.
15. Procédé selon l'une des revendications 13 ou 14, caractérisé en ce que les premier
et deuxième triangles isocèles sont dans des plans parallèles qui sont perpendiculaires
à la première direction de mouvement de la couche de renforcement pratiquement plane.
16. Procédé selon l'une quelconque des revendications 13 à 15, caractérisé en ce que
pour régler l'épaisseur relative des première et deuxième parties de nappe de duvet
fibreux déposée pneumatiquement (21, 22), on règle la position de direction de fabrication
du deuxième triangle rectangle isocèle (4) à l'intérieur de la zone de dépôt de fibres.
17. Procédé selon l'une quelconque des revendications 13 à 16, caractérisé en ce que
l'on applique un niveau d'aspiration plus élevé pour former par dépression la deuxième
partie de nappe de duvet fibreux déposée pneumatiquement (22) que pour former par
dépression la première partie de nappe de duvet fibreux déposée pneumatiquement (21)
afin de compenser la résistance accrue opposée à l'écoulement de l'air par la couche
(20) et la première partie de nappe de duvet fibreux déposée pneumatiquement (21).
18. Procédé selon l'une quelconque des revendications 13 à 17 caractérisé en ce que
l'on forme directement la première partie (21) de la nappe de duvet fibreux déposée
pneumatiquement sur la surface d'une deuxième couche de papier mousseline en mouvement
(23) ayant une largeur au moins aussi grande que la couche de renforcement et qu'une
fois que les couches et les première et deuxième parties de nappe déposée pneumatiquement
ont été retirées de la zone de dépôt de fibres, on superpose à la deuxième partie
de la nappe déposée pneumatiquement (22) une troisième couche de papier mousseline
(24) ayant une largeur au moins aussi grande que la couche de renforcement.
19. Procédé selon la revendication 18, caractérisé en ce que les deuxième et troisième
couches de papier mousseline ont une largeur supérieure à celle de la couche de renforcement
intérieure et que l'on fixe ensemble les bords latéraux des deuxième et troisième
couches en les pliant l'un sur l'autre pour former une enveloppe continue de papier
mousseline autour de la couche de renforcement intérieure et des première et duexième
parties de nappe de duvet fibreux déposée pneumatiquement.
20. Procédé selon la revendication 19, caractérisé en ce que l'on coupe dans l'enveloppe
continue de papier mousseline des segments de tampon absorbant de longueur prédéterminée
et qu'ensuite on les fixe entre une feuille de soutien imperméable à l'humidité et
une feuille supérieure perméable à l'humidité que l'on fixe en les superposant de
manière à former un bandage absorbant jetable.
21. Appareil en ligne pour la fabrication continue d'une nappe de duvet fibreux déposé
pneumatiquement, munie d'une couche intérieure de renforcement pratiquement plane,
imperméable aux fibres dont la largeur est pratiquement égale à celle de la nappe,
appareil caractérisé en ce qu'il comprend:
(a) une source de matière fibreuse sous forme de fibres distinctes,
(b) une suele chambre de dépôt de fibres (12) à laquelle les fibres sont amenées continuellement
de la source,
(c) un élément support perforé (11) en mouvement continu passant à travers la chambre
de dépôt dans un plan pratiquement perpendiculaire à la direction d'écoulement des
fibres,
(d) des moyens d'aspiration (25) situés au voisinage de la surface de l'élément support
perforé (11), à l'opposé de la source de fibres,
(e) des moyens permettant de faire avancer en continu la couche de renforcement dans
la même direction que l'élément support perforé pendant qu'elle est orientée dans
un premier plan parallèle à celui de l'élément support perforé,
(f) un premier moyen de guidage en forme de triangle rectangle isocèle (2, 5) situé
dans une direction perpendiculaire à la direction de mouvement mentionnée de manière
à amener brusquement la couche de renforcement à se plier sur elle-même dans un deuxième
plan perpendiculaire au premier plan,
(g) des moyens (3, 7, 8) permettant d'introduire la couche de renforcement dans la
chambre de dépôt de fibres pendant qu'elle est dans une configuration pliée pour faciliter
la formation par dépression d'une première partie,de nappe de duvet fibreux déposée
pneumatiquement au voisinage de l'élément support perforé,
(h) un deuxième moyen de guidage en forme de triangle rectangle isocèle placé perpendiculaire
à la direction de mouvement (4, 6) de la couche de renforcement à l'intérieur de la
chambre de dépôt de fibres (12) de manière à réorienter brusquement la couche d'une
configuration pliée à une configuration plane dans la premier plan mentionné tout
en ramenant la couche dans la première direction de mouvement pour amener la surface
inférieure de la couche en contact avec la première partie de nappe de duvet fibreux
déposée pneumatiquement et pour faciliter la formation par dépression d'une deuxième
partie de la nappe de duvet fibreux déposée pneumatiquement, auprès de la surface
supérieure de la couche de renforcement, et
(i) des moyens permettant de retirer de la chambre de dépôt de fibres la couche et
les parties de nappe déposées pneumatiquement.
22. Appareil selon la revendication 21, caractérisé en ce que les premier et deuxième
moyens de guidage (2, 4) comprennent des corps triangulaires plans identiques (42,
43, 44, 45, 46, 47) maintenus dans une position parallèle et alignée longitudinalement
par un élément plan (3) reliant leurs hauteurs respectives (40, 41).
23. Appareil selon la revendication 22, caractérisé en ce que les triangles isocèles
plans (2, 4) et l'élément de liaison plan (3) sont réglables d'un bloc (1) dans la
direction de fabrication, de manière à faire varier l'épaisseur relative des première
et deuxième parties de nappe de duvet fibreux déposée pneumatiquement.
24. Appareil selon l'une quelconque des revendications 21 à 23, caractérisé en ce
que les moyens d'aspiration (25) situés auprès de la surface de l'élément support
perforé sont formés d'une chambre à dépression ayant une longueur au moins égale à
celle de la chambre de dépôt de fibres, la chambre à dépression présentant une cloison
intérieure (19) orientée perpendiculairement à la direction de mouvement de la couche,
la cloison étant réglable dans la direction de fabrication pour faciliter son alignement
sur le deuxième moyen de guidage triangulaire (4) à l'intérieur de la chambre et faciliter
ainsi l'alpplication d'un niveau plus élevé d'aspiration pendant la formation de la
deuxième partie de nappe de duvet fibreux déposée pneumatiquement.