Claim for Priority
[0001] This non-provisional patent application is based upon United States Provisional Patent
Application Serial No.
61/025,549, entitled "High Basis Weight TAD Towel Prepared From Coarse Furnish", filed February
1, 2008. The priority of United States Provisional Patent Application Serial No.
61/025,549 is hereby claimed and the disclosure thereof incorporated by reference into this
application.
Technical Field
[0002] Paper toweling pervades modem industrial civilizations, being found in almost all
kitchens and all but the fanciest of away from home restrooms, its wide use largely
attributable to its low cost and ability to rapidly absorb moisture. In most cases,
paper toweling is used for a single event, drying the hands, wiping up a spill, cleaning
a window - then disposed of. Accordingly, low cost is extremely important for almost
all grades. As far as performance goes, absorbency and cross direction wet strength
are considered quite important across the spectrum for almost all grades of toweling
as absorbency is a measure of how well the toweling will perform its intended function
while cross-direction wet strength is a key determinant of the ability of the towel
to resist shredding in use. In the case of kitchen roll toweling and the highest grades
of washroom toweling, tactile properties become very important. In particular, softness
is quite important in these grades. Reconciling low cost and high cross direction
wet strength is not particularly difficult, at least at moderate levels, due to the
availability of low cost permanent wet strength resins; but reconciling low-cost,
high absorbency and softness presents a considerable technical challenge. As absorbency
and softness are roughly inversely related to strength, it is often quite difficult
to obtain the right balance of attributes.
[0003] This invention relates to a high-end paper towel which is suitable for use as kitchen
roll towel and can be made from a non-premium furnish without use of softeners achieving
not only perceived softness which is comparable to toweling made from premium furnishes
but also achieves consumer acceptance exceeding that of leading towels made from premium
furnish.
Background of the Invention
[0004] There are numerous methods described in the patent literature which are said to improve
the attributes of absorbent paper products. Some back up their conclusions with experimental
data; but many present unsubstantiated statements that may need to be taken
cum grano salis. Accordingly, making sense of the hodgepodge of art is far more easily accomplished
using hindsight, the following collection being assembled and the relevance of many
only becoming apparent only after the invention in the application had been made.
[0005] U. S. Patent No. 3,301,746 by Sanford and Sisson, incorporated herein by reference in its entirety, describes a papermaking scheme
for enhancing product attributes usually referred to as through air drying or TAD
which avoids overall web compression by forming a patterned array of densified regions
in the X-Y plane of the sheet to enhance product strength.
[0006] U. S. Pat. No. 4,440,597 by Wells and Hensler, incorporated herein by reference in its entirety, describing a method for increasing
the stretch of a paper web by operating the forming section of a paper machine faster
than the through air dryer section of the paper machine as an improvement to the basic
TAD process for improving the attributes of a through-air-dried sheet. As a result
of the speed differential, the paper web is inundated into the through air dryer fabric
leading to enhanced stretch and absorbency properties in the base sheet and resulting
product. This technique is often referred to a fabric creping.
[0007] U. S. Pat. No. 3,812,000 by Salvucci and Yiannos incorporated herein by reference in its entirety, disclose a technique for producing
a soft tissue by avoiding mechanical compression of an elastomeric containing furnish
until the consistency of the web is at least 80% solids.
U. S. No. 3,821,068 by Shaw, incorporated herein by reference in its entirety, discloses a papermaking scheme
for producing soft tissue by avoiding mechanical compaction until the sheet has been
dried to at least 80% solids.
[0008] U. S. Pat. No. 4,533,457 by Curran and Kershaw, incorporated herein by reference in its entirety;
U. S. Pat. Nos. 5,591,305 and
5,569,358 by Cameron, all incorporated herein by reference in their entirety, disclose low-batting, high-bulk-generating
felt with improved dewatering capabilities.
[0009] Fiber and chemicals can be used to modify the attributes of absorbent paper products.
For example,
U. S. Pat. No. 5,320,710 by Reeves et al., and incorporated herein by reference in its entirety, describes a new furnish combination
extracted from the species Funifera of the genus Hesporaloe in the Agavaceae family.
This furnish has fibers which are very long and which have very fine geometrical attributes
known to enhance towel and tissue performance.
U. S. Pat. No. 3,755,220 by Freimark and Schaftlein, incorporated herein by reference in its entirety, describes a debonding scheme for
maintaining wet strength while reducing product dry strength - a method said to enhance
the handfeel of towel products.
[0010] The use of bulking fibers is said to improve the attributes of the final end absorbent
paper product.
U. S. Pat. No. 3,434,918 by Bemardin,
U. S. Pat. No. 4,204,504 by Lesas et al.,
U. S. Pat. No. 4,431,481 by Drach et al.,
U. S. Pat. No. 3,819,470 by Shaw et al., and
U. S. Pat. No. 5,087324 by Awofeso et al., disclose the use of bulking fibers in papermaking webs to improve product attributes
like thickness, absorbency, and softness. The aforementioned patents are incorporated
herein by reference in their entirety.
[0011] U.S. Pat. No. 5,348,620 by Hermans et al., and incorporated herein by reference, discusses a high consistency/high temperature
fiber treatment-process using a disperser to improve absorbent paper product attributes.
U. S. Pat. No. 4,300,981 by Carstens and
U. S. Pat. No. 3,994,771 by Morgan et al., incorporated herein in their entirety by reference, discloses using certain species
of hardwood like eucalyptus in stratified webs to improve tissue softness.
[0012] Even though the patent literature is replete with suggestions of methods said to
improve attributes of towel and tissue products, R&D departments are in general unable
to provide practical improvements in absorbent paper products merely by choosing one
attribute from column A and another from column B as there are innumerable tradeoffs
involved. For example, two-ply products are usually more absorbent and softer than
comparable one-ply products. These products are usually formed with the Yankee side
of each ply of the web facing outwardly, the Yankee side being typically far smoother
than the air side of the web. In addition, bending stiffness of a two-ply product
with a slip plane can be roughly one fourth that of similar thickness one-ply products
without a slip plane. Since strength and basis weight are directly related while softness
and strength are inversely related, increasing basis weight while preserving softness
can be problematic. However, when basesheet is converted to finished product, there
is typically a converting waste variously estimated at around 15% that must be accounted
for in determining whether the advantage of two-ply construction is worth the cost,
while it is generally understood that paper machines have higher productivity running
heavier sheets such as those found in single ply products. Further, the technology
used to emboss and marry the two plies can have quite detrimental effects on softness
and strength. Further, while chemicals can be used to improve the tactile properties
of the web, they often cause detrimental effects of magnitude not easily predicted
unerringly in advance. Thus, manufacturers of absorbent paper products continue to
spend millions each year to satisfy their continuing need to find new methods to improve
these products. In particular there is a need to for improved methods to produce two-ply
towel products combining absorbency, softness, thickness and strength attributes which
will satisfy the needs of consumers at costs that are acceptable.
Summary of the Invention
[0013] We have found that we can provide a low-cost, high-softness and absorbency toweling
product by providing a multi-ply TAD cellulosic web having a basis weight of at least
32.0 lb/rm, wherein: the short fiber content of the web by weight is at least about
20% to 50%, preferably 30% to 45%, most preferably about 35 to 45%; the short fiber
freeness is above 500 ml; the coarseness of the long fiber component is at least about
15.5 mg/100m, the freeness of the long fiber component is above 600 ml; and the weight-weighted
average fiber length of the total fiber in the web is above about 2.2 mm , preferably
above about 2.3, more preferably 2.4, and most preferably above 2.5. We particularly
prefer to use a fiber blend in which the ratio of coarseness, C, to weight-weighted
average fiber length, l
z, is in excess of 5.3 finding that this helps us provide performance exceeding that
of competitors using fiber blends having rather lower ratios of C/l
z (i.e. <5.0). Even though lower values for C/l
z are generally considered more desirable as leading to improved softness, we find
that, even using this generally less desirable - and less expensive fiber blend, we
can surpass the perceived softness of the market leading brand by using the claimed
combinations of parameters.
[0014] During manufacture of the webs which are ultimately combined to form up the multi-ply
product, we find that it is critical to maintain the fabric crepe levels of the two
webs above 18% while the reel crepe level is kept to no more than about 3% and the
crepe solids is kept to above 96%. When the plies are combined, they are joined by
unusually heavy embossing such that the finished product caliper is above 225 mils/8
sheet (6.2 mils/ 8 sheets per lb/ream of fiber).
Brief Description of the Drawings
[0015] Figure 1 is a graph illustrating consumer preference of two products of the present invention
as compared to the current market leading brand in a home use test.
[0016] Figure 2 is a schematic illustrating a paper machine suitable for producing basesheet for
toweling of the present invention.
[0017] Figures 3A and
3B are schematic illustrations of an emboss pattern suitable for toweling of the present
invention wherein
Figure 3A is the obverse (outer side) side of the towel and
Figure 3B is the reverse.
[0018] Figure 4 presents the SAT absorbent capacity of examples of the present invention relative
to their CD wet tensile strength.
[0019] Figure 5 presents the Sensory Softness of examples of the present invention relative to their
CD wet tensile strength.
[0020] Figures 6, 7 and
8 demonstrate the surprising effect of embossing and caliper upon absorbency.
Description of Preferred Embodiments
[0021] Toweling of the present invention is both extremely heavy and is perceived as extremely
soft when compared to the best of currently available offerings, even though it can
be manufactured from distinctly non-premium furnish using high levels of fabric crepe
combined with low reel crepe. High levels of absorbency can be maintained as softeners
are not required to achieve extreme softness.
Figure 1 illustrates the performance of two grades of toweling of the present invention (heavy,
soft and heavy, strong) as compared to the current market leading brand designated
"B" in home use testing by consumers against a wide variety of toweling. It is considered
extremely significant that both embodiments far surpass the current market leading
brand in almost every category.
[0022] Toweling of the present invention can be produced on conventional through-air dried
machines incorporating a twin wire former as shown in
Figure 2 in which furnish supplied through head box
20 is directed in a jet into the nip formed between forming fabric
24 and transfer fabric
28 as they pass between forming roll
32 and breast roll
36 as forming fabric
24 and transfer fabric
28 translate in continuous loops diverging after passing between forming roll
32 and breast roll
36. After separating from forming fabric
24, transfer fabric
28 passes through dewatering zone
40 in which suction boxes
44 remove moisture from the web and transfer fabric
28 increasing the consistency of the web to perhaps 10 to 25% prior to transfer of the
web to through drying fabric
48. In some instances, it will be advantageous to apply some amount of vacuum as indicated
through vacuum assist boxes
52 in the transfer zone
56 particularly when a considerable amount of fabric crepe is imparted to the web in
transfer zone
56 by rush transfer, as in the present invention in which it is desired that at least
about 18% fabric crepe is applied in transfer zone
56. As through-drying fabric
48 passes around through dryers
60 and
64, the consistency of the web is increased to perhaps 60 to 90%, at which point the
open fabric creped structure more or less permanently imparted to the web can then
be transferred to Yankee cylinder
68 without a major degradation of its properties by contacting the web with adhesive
sprayed on to Yankee cylinder
68 just prior to contact with the translating web. After the web reaches a consistency
of at least about 96%, only light creping is used to dislodge it from Yankee cylinder
68 while the reel speed is controlled relative to the speed of Yankee cylinder
68 such that, at most, about 3% reel crepe is applied to the web.
[0023] Surprisingly, low grade fiber may be used to produce toweling of the present invention,
the furnish comprising about 20 to 50% by weight of short high freeness cellulosic
fiber and up to about 80% of relatively coarse high freeness long fiber having a coarseness
(C) of at least about 15.5 mg/100 m. The weight percent of short high freeness cellulosic
fiber is preferably from about 30% to 45% and more preferably is about 35% to 45%.
It is generally disadvantageous to apply more than light refining to either component
of the furnish. The freeness (CSF) of the short fiber component should be at least
500 ml while the freeness of the long fiber component should be above 600 ml. Fiber
lengths, and proportions should be controlled such that the weight weighted average
fiber length (l
z) of the furnish is at least about 2.2 mm, preferably above 2.3, more preferably above
about 2.4, and most preferably above 2.5, with the ratio of coarseness to weight weighted
average fiber length (C/l
z) exceeding 5.3, in contrast to current market leading brands having lower C/l
z values, typically under 5.0.
[0024] After the web is reeled, sheets are ply bonded together using the overall emboss
pattern of
USP D384,210 shown in
Figures 3A and
3B wherein the embodiments set out are used for the opposing sides of the sheets to
form nested concentric circles on alternating sides of the two ply web with the element
height and penetration being chosen such that the finished product caliper is above
6.2 mils/ 8 sheets per lb/rm of basis weight. We prefer using a stratified headbox
wherein layers enriched in long fiber content are disposed to the exterior of the
finished product. Preferably the long fiber content of the layers forming the exterior
of the product will comprise at least about 50%; more preferably at least about 70%;
and most preferably about 80% by weight of long fiber.
[0025] The creping adhesive used on the Yankee cylinder is capable of cooperating with the
web at intermediate moisture to facilitate transfer from the creping fabric to the
Yankee and to firmly secure the web to the Yankee cylinder as it is dried to a consistency
of 96% or more on the cylinder preferably with a high velocity drying hood. The adhesive
is preferably a hygroscopic, re-wettable, substantially non-crosslinking adhesive.
Examples of preferred adhesives include poly(vinyl alcohol) of the general class described
in United States Patent No.
4,528,316 to Soerens et al. Other suitable adhesives are disclosed in co-pending United States Published Patent
Application
2005/0006040, January 13, 2005, Boettcher, et al., Serial No.
10/409,042 filed April 9, 2003, entitled Improved Creping Adhesive Modifier and Process for Producing Paper Products.
The disclosures of the '316 patent and the Boettcher, et al. application are incorporated
herein by reference. Suitable adhesives are optionally provided with modifiers and
so forth. It is preferred to use crosslinker sparingly or not at all in the adhesive
so that in many cases the resin will be substantially non-crosslinked in use.
[0026] Creping adhesives may comprise and may comprise a thermosetting or non-thermosetting
resin, a film-forming semi-crystalline polymer and optionally an inorganic cross-linking
agent as well as modifiers. Optionally, the creping adhesive of the present invention
may also include any art-recognized components, including, but not limited to, organic
cross linkers, hydrocarbons oils, surfactants, or plasticizers.
[0027] Creping modifiers which may be used include a quaternary ammonium complex comprising
at least one non-cyclic amide. The quaternary ammonium complex may also contain one
or several nitrogen atoms (or other atoms) that are capable of reacting with alkylating
or quatemizing agents. These alkylating or quatemizing agents may contain zero, one,
two, three or four non-cyclic amide containing groups. An amide containing group is
represented by the following formula structure:

where R
7 and R
8 are non-cyclic molecular chains of organic or inorganic atoms. Preferred non-cyclic
bis-amide quaternary ammonium complexes can be of the formula:

where R
1 and R
2 can be long chain non-cyclic saturated or unsaturated aliphatic groups; R
3 and R
4 can be long chain non-cyclic saturated or unsaturated aliphatic groups, a halogen,
a hydroxide, an alkoxylated fatty acid, an alkoxylated fatty alcohol, a polyethylene
oxide group, or an organic alcohol group; and R
5 and R
6 can be long chain non-cyclic saturated or unsaturated aliphatic groups. The modifier
is present in the creping adhesive in an amount of from about 0.05% to about 50%,
more preferably from about 0.25% to about 20%, and most preferably from about 1% to
about 18% based on the total solids of the creping adhesive composition.
[0028] Modifiers include those obtainable from Goldschmidt Corporation of Essen, Germany,
or Process Application Corporation based in Washington Crossing, PA. Appropriate creping
modifiers from Goldschmidt Corporation include, but are not limited to, VARISOFT
® 222LM, VARISOFT
® 222, VARISOFT
® 110, VARISOFT
® 222LT, VARISOFT
® 110 DEG, and VARISOFT
® 238. Appropriate creping modifiers from Process Application Corporation include,
but are not limited to, PALSOFT 580 FDA or PALSOFT 580C.
[0029] Other creping modifiers for use in the present invention include, but are not limited
to, those compounds as described in
WO/01/85109, which is incorporated herein by reference in its entirety.
[0030] Creping adhesives for use according to the present invention include any art recognized
thermosetting or non-thermosetting resin. Resins according to the present invention
are preferably chosen from thermosetting and non-thermosetting polyamide resins or
glyoxylated polyacrylamide resins. Polyamides for use in the present invention can
be branched or unbranched, saturated or unsaturated.
[0031] Polyamide resins for use in the present invention may include polyaminoamide-epichlorohydrin
(PAE) resins of the same general type employed as wet strength resins. PAE resins
are described, for example, in "
Wet-Strength Resins and Their Applications," Ch. 2, H. Espy entitled Alkaline-Curing
Polymeric Amine-Epichlorohydrin Resins, which is incorporated herein by reference in its entirety. Preferred PAE resins
for use according to the present invention include a water-soluble polymeric reaction
product of an epihalohydrin, preferably epichlorohydrin, and a water-soluble polyamide
having secondary amine groups derived from a polyalkylene polyamine and a saturated
aliphatic dibasic carboxylic acid containing from about 3 to about 10 carbon atoms.
[0032] A non-exhaustive list of non-thermosetting cationic polyamide resins can be found
in United States Patent No.
5,338,807, issued to Espy et al. and incorporated herein by reference. The non-thermosetting resin may be synthesized
by directly reacting the polyamides of a dicarboxylic acid and methyl bis(3-aminopropyl)amine
in an aqueous solution, with epichlorohydrin. The carboxylic acids can include saturated
and unsaturated dicarboxylic acids having from about 2 to 12 carbon atoms, including
for example, oxalic, malonic, succinic, glutaric, adipic, pilemic, suberic, azelaic,
sebacic, maleic, itaconic, phthalic, and terephthalic acids. Adipic and glutaric acids
are preferred, with adipic acid being the most preferred. The esters of the aliphatic
dicarboxylic acids and aromatic dicarboxylic acids, such as the phathalic acid, may
be used, as well as combinations of such dicarboxylic acids or esters.
[0033] Thermosetting polyamide resins for use in the present invention may be made from
the reaction product of an epihalohydrin resin and a polyamide containing secondary
amine or tertiary amines. In the preparation of such a resin, a dibasic carboxylic
acid is first reacted with the polyalkylene polyamine, optionally in aqueous solution,
under conditions suitable to produce a water-soluble polyamide. The preparation of
the resin is completed by reacting the water-soluble amide with an epihalohydrin,
particularly epichlorohydrin, to form the water-soluble thermosetting resin.
[0034] The of preparation of water soluble, thermosetting polyamide-epihalohydrin resin
is described in United States Patents Nos.
2,926,116;
3,058,873; and
3,772,076 issued to Keim, all of which are incorporated herein by reference in their entirety.
[0035] The polyamide resin may be based on DETA instead of a generalized polyamine. Two
examples of structures of such a polyamide resin are given below. Structure 1 shows
two types of end groups: a di-acid and a mono-acid based group:

Structure 2 shows a polymer with one end-group based on a di-acid group and the other
end-group based on a nitrogen group:

[0036] Note that although both structures are based on DETA, other polyamines may be used
to form this polymer, including those, which may have tertiary amide side chains.
[0037] The polyamide resin has a viscosity of from about 80 to about 800 centipoise and
a total solids of from about 5% to about 40%. The polyamide resin is present in the
creping adhesive according to the present invention in an amount of from about 0%
to about 99.5%. According to another embodiment, the polyamide resin is present in
the creping adhesive in an amount of from about 20% to about 80%. In yet another embodiment,
the polyamide resin is present in the creping adhesive in an amount of from about
40% to about 60% based on the total solids of the creping adhesive composition.
[0038] Polyamide resins for use according to the present invention can be obtained from
Ondeo-Nalco Corporation, based in Naperville, Illinois, and Hercules Corporation,
based in Wilmington, Delaware. Creping adhesive resins for use according to the present
invention from Ondeo-Nalco Corporation include, but are not limited to, CREPECCEL
® 675NT, CREPECCEL
® 675P and CREPECCEL
® 690HA. Appropriate creping adhesive resins available from Hercules Corporation include,
but are not limited to, HERCULES 82-176, Unisoft 805 and CREPETROL A-6115.
[0039] Other polyamide resins for use according to the present invention include, for example,
those described in United States Patent Nos.
5,961,782 and
6,133,405, both of which are incorporated herein by reference.
[0040] The creping adhesive may also comprise a film-forming semi-crystalline polymer. Film-forming
semi-crystalline polymers for use in the present invention can be selected from, for
example, hemicellulose, carboxymethyl cellulose, and most preferably includes polyvinyl
alcohol (PVOH). Polyvinyl alcohols used in the creping adhesive can have an average
molecular weight of about 13,000 to about 124,000 daltons. According to one embodiment,
the polyvinyl alcohols have a degree of hydrolysis of from about 80% to about 99.9%.
According to another embodiment, polyvinyl alcohols have a degree of hydrolysis of
from about 85% to about 95%. In yet another embodiment, polyvinyl alcohols have a
degree of hydrolysis of from about 86% to about 90%. Also, according to one embodiment,
polyvinyl alcohols preferably have a viscosity, measured at 20 degree centigrade using
a 4% aqueous solution, of from about 2 to about 100 centipoise. According to another
embodiment, polyvinyl alcohols have a viscosity of from about 10 to about 70 centipoise.
In yet another embodiment, polyvinyl alcohols have a viscosity of from about 20 to
about 50 centipoise.
[0041] Typically, if polyvinyl alcohol is included, it is present in the creping adhesive
in an amount of from about 10% to 90% or 20% to about 80%. In some embodiments, the
polyvinyl alcohol is present in the creping adhesive in an amount of from about 40%
to about 60%, by weight, based on the total solids of the creping adhesive composition.
[0042] Polyvinyl alcohols for use according to the present invention include those obtainable
from Monsanto Chemical Co. and Celanese Chemical. Appropriate polyvinyl alcohols from
Monsanto Chemical Co. include Gelvatols, including, but not limited to, GELVATOL 1-90,
GELVATOL 3-60, GELVATOL 20-30, GELVATOL 1-30, GELVATOL 20-90, and GELVATOL 20-60.
Regarding the Gelvatols, the first number indicates the percentage residual polyvinyl
acetate and the next series of digits when multiplied by 1,000 gives the number corresponding
to the average molecular weight.
[0043] Celanese Chemical polyvinyl alcohol products for use in the creping adhesive (previously
named Airvol products from Air Products until October 2000) are listed below:
| Table 1 |
| Polyvinyl Alcohol for Creping Adhesive |
| Grade |
% Hydrolysis |
Viscosity, cps1 |
pH |
Volatiles, % Max. |
Ash, % Max.3 |
| Super Hydrolyzed |
|
|
|
|
|
| Celvol 125 |
99.3+ |
28-32 |
5.5-7.5 |
5 |
1.2 |
| Celvol 165 |
99.3+ |
62-72 |
5.5-7.5 |
5 |
1.2 |
| Fully Hydrolyzed |
|
|
|
|
| Celvol 103 |
98.0-98.8 |
3.5-4.5 |
5.0-7.0 |
5 |
1.2 |
| Celvol 305 |
98.0-98.8 |
4.5-5.5 |
5.0-7.0 |
5 |
1.2 |
| Celvol 107 |
98.0-98.8 |
5.5-6.6 |
5.0-7.0 |
5 |
1.2 |
| Celvol 310 |
98.0-98.8 |
9.0-11.0 |
5.0-7.0 |
5 |
1.2 |
| Celvol 325 |
98.0-98.8 |
28.0-32.0 |
5.0-7.0 |
5 |
1.2 |
| Celvol 350 |
98.0-98.8 |
62-72 |
5.0-7.0 |
5 |
1.2 |
| Intermediate Hydrolyzed |
| Celvol 418 |
91.0-93.0 |
14.5-19.5 |
4.5-7.0 |
5 |
0.9 |
| Celvol 425 |
95.5-96.5 |
27-31 |
4.5-6.5 |
5 |
0.9 |
| Partially Hydrolyzed |
| Celvol 502 |
87.0-89.0 |
3.0-3.7 |
4.5-6.5 |
5 |
0.9 |
| Celvol 203 |
87.0-89.0 |
3.5-4.5 |
4.5-6.5 |
5 |
0.9 |
| Celvol 205 |
87.0-89.0 |
5.2-6.2 |
4.5-6.5 |
5 |
0.7 |
| Celvol 513 |
86.0-89.0 |
13-15 |
4.5-6.5 |
5 |
0.7 |
| Celvol523 |
87.0-89.0 |
23-27 |
4.0-6.0 |
5 |
0.5 |
| Celvol 540 |
87.0-89.0 |
45-55 |
4.0-6.0 |
5 |
0.5 |
| 1 4% aqueous solution, 20°C |
|
|
|
|
|
[0044] The creping adhesive may also comprise one or more inorganic cross-linking salts
or agents. Such additives are believed best used sparingly or not at all in connection
with the present invention. A non-exhaustive list of multivalent metal ions includes
calcium, barium, titanium, chromium, manganese, iron, cobalt, nickel, zinc, molybdenium,
tin, antimony, niobium, vanadium, tungsten, selenium, and zirconium. Mixtures of metal
ions can be used. Preferred anions include acetate, formate, hydroxide, carbonate,
chloride, bromide, iodide, sulfate, tartrate, and phosphate. An example of a preferred
inorganic cross-linking salt is a zirconium salt. The zirconium salt for use according
to one embodiment of the present invention can be chosen from one or more zirconium
compounds having a valence of plus four, such as ammonium zirconium carbonate, zirconium
acetylacetonate, zirconium acetate, zirconium carbonate, zirconium sulfate, zirconium
phosphate, potassium zirconium carbonate, zirconium sodium phosphate, and sodium zirconium
tartrate. Appropriate zirconium compounds include, for example, those described in
United States Patent No.
6,207,011, which is incorporated herein by reference.
[0045] The inorganic cross-linking salt can be present in the creping adhesive in an amount
of from about 0% to about 30%. In another embodiment, the inorganic cross-linking
agent can be present in the creping adhesive in an amount of from about 1% to about
20%. In yet another embodiment, the inorganic cross-linking salt can be present in
the creping adhesive in an amount of from about 1% to about 10% by weight based on
the total solids of the creping adhesive composition. Zirconium compounds for use
according to the present invention include those obtainable from EKA Chemicals Co.
(previously Hopton Industries) and Magnesium Elektron, Inc. Appropriate commercial
zirconium compounds from EKA Chemicals Co. are AZCOTE 5800M and KZCOTE 5000 and from
Magnesium Elektron, Inc. are AZC or KZC.
[0046] Optionally, the creping adhesive according to the present invention can include any
other art recognized components, including, but not limited to, organic cross-linkers,
hydrocarbon oils, surfactants, amphoterics, humectants, plasticizers, or other surface
treatment agents. An extensive, but non-exhaustive, list of organic cross-linkers
includes glyoxal, maleic anhydride, bismaleimide, bis acrylamide, and epihalohydrin.
The organic cross-linkers can be cyclic or non-cyclic compounds. Plastizers for use
in the present invention can include propylene glycol, diethylene glycol, triethylene
glycol, dipropylene glycol, and glycerol.
[0047] The creping adhesive may be applied as a single composition or may be applied in
its component parts. More particularly, the polyamide resin may be applied separately
from the polyvinyl alcohol (PVOH) and the modifier.
[0048] Unless otherwise specified, "basis weight", BWT, bwt and so forth refers to the weight
of a 3000 square foot ream of product in pounds. Likewise, percent or like terminology
refers to weight percent on a dry basis, that is to say, with no free water present,
which is equivalent to 5% moisture in the fiber. Throughout this specification and
claims, it is to be understood that, unless otherwise specified, physical properties
are measured after the web has been conditioned according to TAPPI standards. If no
test method is explicitly set forth for measurement of any quantity mentioned herein,
it is to be understood that TAPPI standards should be applied.
[0049] Absorbency of the inventive products is measured with a simple absorbency tester.
The simple absorbency tester is a particularly useful apparatus for measuring the
hydrophilicity and absorbency properties of a sample of tissue, napkins, or towel.
In this test a sample of tissue, napkins, or towel 2.0 inches in diameter is mounted
between a top flat plastic cover and a bottom grooved sample plate. The tissue, napkin,
or towel sample disc is held in place by a 1/8 inch wide circumference flange area.
The sample is not compressed by the holder. De-ionized water at 73°F. is introduced
to the sample at the center of the bottom sample plate through a 1 mm diameter conduit.
This water is at a hydrostatic head of minus 5 mm. Flow is initiated by a pulse introduced
at the start of the measurement by the instrument mechanism. Water is thus imbibed
by the tissue, napkin, or towel sample from this central entrance point radially outward
by capillary action. When the rate of water imbibation decreases below 0.005 gm water
per 5 seconds, the test is terminated. The amount of water removed from the reservoir
and absorbed by the sample is weighed and reported as grams of water per square meter
of sample or grams of water per gram of sheet. In practice, an M/K Systems Inc. Gravimetric
Absorbency Testing System is used. This is a commercial system obtainable from M/K
Systems Inc., 12 Garden Street, Danvers, Mass., 01923. WAC, or water absorbent capacity,
also referred to as SAT, is actually determined by the instrument itself WAC is defined
as the point where the weight versus time graph has a "zero" slope, i.e., the sample
has stopped absorbing. The termination criteria for a test are expressed in maximum
change in water weight absorbed over a fixed time period. This is basically an estimate
of zero slope on the weight versus time graph. The program uses a change of 0.005
g over a 5 second time interval as termination criteria; unless "Slow SAT" is specified
in which case the cut off criteria is 1 mg in 20 seconds.
[0050] Water absorbency rate is measured in seconds and is the time it takes for a sample
to absorb a 0.1 gram droplet of water disposed on its surface by way of an automated
syringe. The test specimens are preferably conditioned at 23°C ± 1 °C (73.4°F±1.8°F.)
at 50% relative humidity. For each sample, 4 3X3 inch test specimens are prepared.
Each specimen is placed in a sample holder such that a high intensity lamp is directed
toward the specimen. 0.1 ml of water is deposited on the specimen surface and a stop
watch is started. When the water is absorbed, as indicated by lack of further reflection
of light from the drop, the stopwatch is stopped and the time recorded to the nearest
0.1 seconds. The procedure is repeated for each specimen and the results averaged
for the sample. SAT Rate is determined by graphing the weight of water absorbed by
the sample (in grams) against the square root of time (in seconds). The SAT rate is
the best fit slope between 10 and 60 percent of the end point (grams of water absorbed).
[0051] Dry tensile strengths (MD and CD), stretch, ratios thereof, break modulus, stress
and strain are measured with a standard Instron test device or other suitable elongation
tensile tester which may be configured in various ways, typically using 3 or 1 inch
wide strips of tissue or towel, conditioned at 50% relative humidity and 23°C (73.4°F),
with the tensile test run at a crosshead speed of 2 in/min for modulus, 10 in/min
for tensile. For purposes of calculating modulus values, inch wide specimens were
pulled at 0.5 inches per minute so that a larger number of data points were available.
Unless otherwise clear from the context, stretch refers to stretch (elongation) at
break. Break modulus is the ratio of peak load to stretch at peak load. Tensile modulus,
reported in grams per inch per percent strain, is determined by the same procedure
used for tensile strength except that the modulus recorded is the geometric mean of
the chord slopes of the cross direction and machine direction load-strain curves from
a value of 0 to 100 grams, and a sample width of only one inch is used.
[0052] GMT refers to the geometric mean tensile strength of the CD and MD tensile. Tensile
energy absorption (TEA) is measured in accordance with TAPPI test method T494 om-01.
[0053] Initial MD modulus refers to the maximum MD modulus below 5% strain.
[0054] Wet tensile is measured by the Finch cup method. The Finch cup method uses a three-inch
wide strip of tissue that is folded into a loop, clamped in the Finch Cup, then immersed
in a water. The Finch Cup, which is available from the Thwing-Albert Instrument Company
of Philadelphia, Pa., is mounted onto a tensile tester equipped with a 2.0 pound load
cell with the flange of the Finch Cup clamped by the tester's lower jaw and the ends
of tissue loop clamped into the upper jaw of the tensile tester. The sample is immersed
in water that has been adjusted to a pH of 7.0.±0.01 and the tensile is tested after
a 5 second immersion time. On most test equipment, as the measurement is taken of
a loop, the indicated load reading should be divided by two to reflect the intrinsic
properties of the sheet.
[0055] Wet or dry tensile ratios are simply ratios of the values determined by way of the
foregoing methods. Unless otherwise specified, a tensile property is a dry sheet property.
[0056] The void volume and /or void volume ratio as referred to hereafter, are determined
by saturating a sheet with a nonpolar liquid and measuring the amount of liquid absorbed.
The volume of liquid absorbed is equivalent to the void volume within the sheet structure.
The percent weight increase (PWI) is expressed as grams of liquid absorbed per gram
of fiber in the sheet structure times 100, as noted hereinafter. More specifically,
for each single-ply sheet sample to be tested, select 8 sheets and cut out a 1 inch
by 1 inch square (1 inch in the machine direction and 1 inch in the cross-machine
direction). For multi-ply product samples, each ply is measured as a separate entity.
Multiple samples should be separated into individual single plies and 8 sheets from
each ply position used for testing. Weigh and record the dry weight of each test specimen
to the nearest 0.0001 gram. Place the specimen in a dish containing POROFIL.TM. liquid
having a specific gravity of 1.875 grams per cubic centimeter, available from Coulter
Electronics Ltd., Northwell Drive, Luton, Beds, England; Part No. 9902458.) After
10 seconds, grasp the specimen at the very edge (1-2 Millimeters in) of one corner
with tweezers and remove from the liquid. Hold the specimen with that corner uppermost
and allow excess liquid to drip for 30 seconds. Lightly dab (less than 1/2 second
contact) the lower corner of the specimen on #4 filter paper (Whatman Lt., Maidstone,
England) in order to remove any excess of the last partial drop. Immediately weigh
the specimen, within 10 seconds, recording the weight to the nearest 0.0001 gram.
The PWI for each specimen, expressed as grams of POROFIL per gram of fiber, is calculated
as follows:

wherein
"W1" is the dry weight of the specimen, in grams; and
"W2" is the wet weight of the specimen, in grams.
[0057] The PWI for all eight individual specimens is determined as described above and the
average of the eight specimens is the PWI for the sample.
[0058] The void volume ratio is calculated by dividing the PWI by 1.9 (density of fluid)
to express the ratio as a percentage, whereas the void volume (gms/gm or g/g) is simply
the weight increase ratio; that is, PWI divided by 100.
[0059] Fiber lengths and coarseness incorporated herein are determined using the HiRes Fiber
Quality Analyzer manufactured by OpTest Equipment, Inc of Hawksbury, Ontario Canada.
[0060] Subjective product attributes are often best evaluated using test protocols in which
a consumer uses and evaluates a product. In a "monadic" test, a consumer will use
a single product and evaluate its characteristics using a standard scale. In paired
comparison tests, the consumers are given samples of two different products and asked
to rate each
vis-à-vis the other for either specific attributes or overall preference. Sensory softness
is a subjectively measured tactile property that approximates consumer perception
of sheet softness in normal use. Softness is usually measured by 20 trained panelists
and includes internal comparison among product samples. The results obtained are statistically
converted to a useful comparative scale.
[0061] Fpm refers to feet per minute while consistency refers to the weight percent fiber
of the web. A nascent web of 10 percent consistency is 10 weight percent fiber and
90 weight percent water.
[0062] Fabric Crepe Ratio is an expression of the speed differential between the creping
fabric and the transfer cylinder or surface and is defined as the ratio of the transfer
cylinder speed and the creping fabric speed calculated as:

[0063] Fabric Crepe can also be expressed as a percentage calculated as:

[0064] Reel Crepe is a measure of the speed differential between the Yankee dryer and the
take-up reel onto which the paper is being wound and is measured in a similar way:

and

[0065] Similarly, the Aggregate Crepe Ratio is defined as:

and

[0067] PLI or pli means pounds force per linear inch.
[0068] Velocity delta means a difference in speed.
[0069] Pusey and Jones hardness (indentation) is measured in accordance with ASTM D 531,
and refers to the indentation number (standard specimen and conditions).
[0070] Calipers reported herein are 8-sheet calipers unless otherwise indicated. The sheets
are stacked and the caliper measurement taken about the central portion of the stack.
Preferably, the test samples are conditioned in an atmosphere of 23° ± 1.0°C (73.4°
± 1.8°F) at 50% relative humidity for at least about 2 hours and then measured with
a Thwing-Albert Model 89-II-JR or Progage Electronic Thickness Tester with 2-in (50.8-mm)
diameter anvils, 539 ± 10 grams dead weight load, and 0.231 in./sec descent rate.
For finished product testing, each sheet of product to be tested must have the same
number of plies as the product is sold. For base sheet testing off of the paper machine
reel, single plies are used with eight sheets being selected and stacked together.
Specific volume is determined from basis weight and caliper.
Example 1
[0071] Towel base sheets were produced on a TAD paper machine having the configuration shown
in Figure 2. The base sheets were produced using a furnish containing sixty percent
Southern SWK and forty percent Southern HWK. The base sheet also contained broke in
amounts ranging from seventeen to twenty-five percent of the total furnish. The sheets
were produced using a three-layered head box with the layer that contacted the Yankee
dryer comprised of 100% SWK. The sheet was shaped on a Voith 44G TAD fabric having
a standard warp and a contact area of eighteen percent. Refining was used to control
the dry strength of the base sheets, while wet strength and wet/dry ratio was produced
by addition of a polyaminoamide epichlorohydrin permanent wet strength resin and carboxymethylcellulose
to the wet end. Hercules Prosoft TQ-456, an imidazolinium-based debonder containing
a poly-propylene glycol oleate was added to wet end during manufacture of one of the
towel base sheets in the amount of 5.5 lbs/ton. The sheets were creped at a fabric
crepe of 18 to 20 percent, while the reel crepe ranged from -0.3 to 0.2 percent. The
sheets were creped from the Yankee dryer using a creping blade having a blade of twenty
degrees. The base sheets were dried to about 80 percent solids on the through-dryer
while the reel moisture was controlled to a value of between 2.0 and 2.5 percent.
The physical properties of the base sheets are shown in Tablel-1.
| Table 1-1 |
| Base Sheet Physical Properties |
| Product |
G-2 (No Debonder) |
G-3 (Debonder Added) |
| Basis Weight (lbs/ream) |
19.15 |
19.10 |
| Caliper (mils/8 sheets) |
106.1 |
114.8 |
| MD Tensile (g/3") |
2853 |
1578 |
| CD Tensile (g/3") |
2510 |
1594 |
| GM Tensile (g/3") |
2675 |
1586 |
| Tensile Ratio |
1.14 |
0.99 |
| MD Stretch (%) |
16.8 |
18.6 |
| CD Stretch (%) |
6.4 |
6.4 |
| CD Wet Tensile - Finch (g/3") |
764 |
490 |
| CD Wet/Dry - Finch (%) |
30.4 |
30.8 |
| SAT Capacity (g/sq meter) |
539 |
511 |
| SAT Capacity (g/g) |
8.7 |
8.2 |
| SAT Rate (g/sec^0.5) |
0.18 |
0.16 |
| GM Break Modulus (g/%) |
254.6 |
143.6 |
| GM Tensile Modulus (g/in/%) |
140.3 |
76.1 |
[0072] The base sheets were converted to finished product by embossing them using the emboss
pattern shown in
Figures 3A and
3B. The finished product properties are shown in Table 2-2. As a reference, the physical
properties of competitive product "V", a high-weight double-recreped product are also
shown. In consumer tests, this product has received the highest scores for overall
performance and for most important attribute ratings of any commercially- available
product in our experience.
| Table 1-2 |
| Finished Product Physical Properties |
| Product |
PH47.1 (G-2) |
PH48.1 (G-3) |
"V" (Average of two samples) |
| Basis Weight (lbs/ream) |
36.92 |
36.65 |
41.7 |
| Caliper (mils/8 sheets) |
239.1 |
239.8 |
211.6 |
| MD Tensile (g/3") |
4802 |
2196 |
1423 |
| CD Tensile (g/3") |
3565 |
1742 |
933 |
| GM Tensile (g/3") |
4137 |
1956 |
1152 |
| Tensile Ratio |
1.35 |
1.26 |
1.53 |
| MD Stretch (%) |
16.0 |
17.1 |
22.4 |
| CD Stretch (%) |
8.2 |
8.3 |
17.6 |
| CD Wet Tensile - Finch (g/3") |
1001 |
515 |
522 |
| CD Wet/Dry - Finch (%) |
28.1 |
29.5 |
55.9 |
| Perf Tensile (g/3") |
961 |
431 |
367 |
| SAT Capacity (g/sq meter) |
539 |
544 |
568 |
| SAT Capacity (g/g) |
8.97 |
9.11 |
8.37 |
| SAT Rate (g/sec^0.5) |
0.20 |
0.15 |
0.12 |
| GM Break Modulus (g/%) |
363.8 |
163.9 |
58.2 |
| GM Tensile Modulus (g/in/%) |
77.4 |
37.7 |
14.1 |
| Macbeth Brightness (%) |
79.1 |
79.4 |
84.2 |
| Macbeth L* |
94.4 |
94.7 |
96.5 |
| Macbeth a* |
-0.74 |
-0.88 |
-1.0 |
| Macbeth b* |
5.65 |
5.99 |
5.31 |
| Roll Diameter (inches) |
5.60 |
5.58 |
4.88 |
| Roll Compression (%) |
9.6 |
8.0 |
7.4 |
| Sensory Softness |
3.84 |
7.88 |
13.9 |
[0073] Both the product prototypes and competitive product "V" were placed in Monadic Home
Use tests. The test results are shown in Table 1-3. The results show that the softer
prototype, G-3, was preferred by consumers over the G-2 towel for overall performance.
Surprisingly, the softer product had a substantially higher overall rating, even though
the stronger G-2 product had equivalent ratings for most product attributes, except
those related to product softness. Also, the G-3 product obtained an overall performance
rating and similar scores for most attributes to the competitive "V" towel. It is
considered quite surprising that the product of the present invention is able to so
closely match a product made by the far more expensive double recrepe process on absorbency,
strength and thickness and actually achieve an overall acceptance rating equivalent
to that of the very high end retail towel "V". On monadic HUT evaluations, we have
found that a difference of 3 points is typically significant at about the 90% confidence
level - there is a 90% probability that consumers will on average rate the higher
testing product as significantly better.
| Table 1-3 |
| Monadic HUT Ratings (0 - 100) |
| Product |
Overall Rating |
Absorbency Rating |
Strength Rating |
Thickness Rating |
Softness Rating |
| G-2 |
81 |
87 |
89 |
88 |
48 |
| G-3 (Current Invention) |
87 |
88 |
85 |
86 |
76 |
| "V" (avg. of two HUT's) |
86 |
88 |
87 |
88 |
91 |
Example 2
[0074] Premium 2-ply TAD towel basesheets were produced having two CD wet strength targets
(i.e., 470 g/3" and 740 g/3") with two levels of basis weight (17.7 lb/rm and 19.3
lb/rm).
[0075] Webs were formed using 60% pine, 40% hardwood plus 30% broke, base sheet strength
being altered by changing refining levels (i.e., pine and Yankee side layer furnishes
were refined to different levels of freeness). Target GM tensile strength levels for
the trial were: 1600 g/3" & 2700 g/3" as set forth in Table 2-1.
| Table 2-1 |
| Experimental Design - Super Premium TAD Towel Base Sheet |
| Factors |
Levels |
| Target Furnish |
60%-Pine / 40%-Hardwood / 30%-Broke |
| Refining |
Pine refiner varied to control strength |
| |
Yankee layer tickler refiner varied to control strength |
| Wet Strength Resin (Amres) |
∼16.0 lb/ton |
| Dry Strength Resin (CMC) |
∼2.7 lb/ton |
| Wet End Softener (Hercules TQ-456) |
None or 5.5 lb/ton (overall) on an as received basis. 2.75 lb/T added to the suction
side of Air Layer blend chest stock pump and 2.75 lb/T added to the suction side of
the suction side of Middle Layer blend chest stock pump |
| Fabric Crepe Level |
16 to 19% |
| TAD Fabric Style |
Voith 44G, standard warp at 18% contact area |
| TAD Spray Release |
∼70 mg/m2 |
| Post TAD No. 2 Moisture |
∼18% |
| Yankee Crepe Adhesive |
∼33 mg/m2 |
| Crepe Blade Bevel, degrees |
20° |
| Reel Crepe |
2.2 to 2.7% |
| Target Basis Weight, |
16.5 and 17.9 (OD) |
| lb/3000 ft2 |
17.7 and 19.3 (Conditioned to 7% Moisture) |
[0076] Table 2-2 gives the detailed process conditions used to make the base sheets. As
can be seen from the table, for one of the prototypes, the addition of debonder was
required in order to obtain the desired physical properties. No debonder was needed
to produce the other base sheets. The base sheet physical properties are shown in
Table 2-3.
| Table 2-2 |
| Paper Machine Process Conditions Used to Make Super Premium TAD Towel Base Sheets |
| Trial Cell ID |
Q-1 |
Q-2 |
Q-3 |
Q-4 |
| Prototype Description |
Low str Med wt |
Low str High wt. |
High str Med wt. |
High str High wt |
| Fabric Crepe, % |
16.0 |
17.0 |
18.5 |
18.5 |
| Pine/HardwoodBroke, % |
60/40/30 |
60/40/30 |
60/40/30 |
60/40/30 |
| Yankee Layer: Pine/HWBroke, % |
100/0/0 |
100/0/0 |
100/0/0 |
100/0/0 |
| Middle Layer: Pine/HWBroke, % |
0/100/91 |
0/100/91 |
0/100/91 |
0/100/91 |
| Air Layer: Pine/HW/Broke, % |
26/74/0 |
26/74/0 |
26/74/0 |
26/74/0 |
| Reel Crepe, % |
+2.4 |
+2.0 |
+2.1 |
+2.4 |
| Reel Speed, fpm |
3515 |
3564 |
3354 |
3344 |
| TAD Release, mg/m2 |
70 |
70 |
70 |
70 |
| Wet Strength Resin, lbs/ton |
15.8 |
15.8 |
15.0 |
15.0 |
| Dry Strength Resin, lbs/ton |
2.7 |
2.7 |
2.4 |
2.4 |
| Wet End Softener (TQ-456) |
0/0 |
2.75/2.75 |
0/0 |
0/0 |
| AL/ML, lbs/ton of production |
|
|
|
|
| Crepe Adhesive-Total, mg/m2 |
33.0 |
33.0 |
33.0 |
33.0 |
| PVOH, mg/m2 |
19.6 |
19.6 |
19.6 |
19.6 |
| PAE, mg/m2 |
13.1 |
13.1 |
13.1 |
13.1 |
| Modifier, mg/m2 |
0.3 |
0.3 |
0.3 |
0.3 |
| Crepe Blade, degrees |
20 |
20 |
20 |
20 |
| Reel Moisture, % |
2.6 |
2.7 |
2.2 |
2.6 |
| Post TAD No. 2 Moisture, % |
17.5 |
18.5 |
18.0 |
17.9 |
| Fabric Crepe, % |
16.0 |
17.0 |
18.5 |
18.5 |
| Table 2-3 |
| Physical Property Data - Tested after TAPPI conditioning |
| Properties |
Q-1 |
Q-2 |
Q-3 |
Q-4 |
| Prototype Description |
Low Strength/ Medium Weight |
Low Strength/ High Weight |
High Strength/ Medium Weight |
High Strength/ High Weight |
| Basis Weight, lb/rm |
18.16 |
19.73 |
17.89 |
19.30 |
| Caliper, mils/8 sheets |
108.14 |
116.64 |
101.46 |
109.50 |
| MDT, g/3" |
1750.50 |
1667.87 |
2868.44 |
3004.33 |
| CDT, g/3" |
1825.50 |
1677.53 |
2757.22 |
2818.00 |
| GMDT, g/3" |
1786.82 |
1672.36 |
2812.28 |
2909.02 |
| MDST, % |
22.15 |
21.86 |
22.92 |
22.60 |
| CDST, % |
6.57 |
6.17 |
6.86 |
6.62 |
| Tensile Ratio |
0.96 |
1.00 |
1.04 |
1.07 |
| GM Break Mod, g/% |
147.26 |
143.35 |
223.59 |
238.65 |
| CWDT-Finch, g/3" |
538.10 |
542.90 |
838.12 |
830.37 |
| Wet/Dry Ratio,% |
0.30 |
0.32 |
0.30 |
0.29 |
| SAT (2-ply), g/m2 |
575.12 |
560.65 |
616.78 |
574.35 |
Example 3
[0077] Four premium 2-ply TAD towel basesheets were produced including
- Cell R-1: 16.2 lb/rm and 640 g/3" CDWT;
- Cell R-2: 16.2 lb/rm and 485 g/3" CDWT;
- Cell R-3: 17.7 lb/rm and 640 g/3" CDWT; and
- Cell R-4: 19.3 lb/rm and 640 g/3" CDWT.
[0078] All basesheets were produced without addition of softener. Toweling web was formed
using 60% pine, 40% hardwood plus 30% broke. Basesheet strength was altered by changing
refining levels (i.e., pine and Yankee-side layer furnishes were refined to different
levels of freeness). The target GM tensile strength levels for the trial were: 1640
g/3" (Low Tensile Strength) and 2200 g/3" (Medium Tensile Strength).
[0079] Details of the experimental design are given in Table 3-1.
| Table 3-1 |
| Super Premium TAD Towel Basesheet |
| Factors |
Levels |
| Target Furnish |
60%-Pine / 40%-Hardwood / 30%-Broke |
| Refining |
Pine refiner varied to control strength |
| |
Yankee layer tickler refiner varied to control strength |
| Wet Strength Resin (Amres) |
∼13.3 lb/ton |
| Dry Strength Resin (CMC) |
∼2.7 lb/ton |
| Wet End Softener (Hercules TQ-456) |
None. |
| Fabric Crepe Level |
16 to 19% |
| TAD Fabric Style |
Voith 44G, standard warp at 18% contact area |
| TAD Spray Release |
∼60 mg/m2 |
| Post TAD No. 2 Moisture |
∼18% |
| Yankee Crepe Adhesive Add-on |
∼33 mg/m2 |
| Crepe Blade Bevel, degrees |
20° |
| Reel Crepe |
1.0 to 2.0% |
| Target Basis Weight, lb/3000 ft2 |
16.2, 17.7, and 19.3 (Conditioned to 7% Moisture) |
[0080] Table 3-2 gives the detailed process conditions used to make the four basesheets.
Table 3-3 gives the detailed physical property data for the basesheets made during
the trial.
| Table 3-2 |
| Paper Machine Process Conditions Used to Make Super Premium TAD Towel Basesheets Table |
| Trial Cell ID |
R-1 |
R-2 |
R-3 |
R-4 |
| Prototype Description |
16.2 lb/rml Medium Strength |
16.2 lb/rm/ Low Strength |
17.7 lb/rm/ Medium Strength |
19.3 lb/rm/ Medium Strength |
| Rush/Drag, fpm |
304 |
300 |
300 |
300 |
| Fabric Crepe, % |
16.0 |
16.0 |
18.0 |
18.0 |
| Pine/HardwoodBroke, % |
60/40/30 |
60/40/30 |
60/40/30 |
60/40/30 |
| Yankee Layer: Pine/HWBroke, % |
100/0/0 |
100/0/0 |
100/0/0 |
100/0/0 |
| Middle Layer: Pine/HWBoke, % |
0/9/91 |
0/9/91 |
0/9/91 |
0/9/91 |
| Air Layer: Pine/HWBroke, % |
26/74/0 |
26/74/0 |
26/74/0 |
26/74/0 |
| Reel Crepe, % |
+2.0 |
+1.6 |
+1.0 |
+1.0 |
| Reel Speed (fpm) |
3822 |
3840 |
3368 |
3414 |
| TAD Release, mg/m2 |
60 |
60 |
60 |
60 |
| Wet Strength Resin, lbs/ton |
13.3 |
13.3 |
13.2 |
13.4 |
| Dry Strength Resin, lbs/ton |
2.7 |
2.7 |
2.7 |
2.8 |
| Crepe Adhesive-Total, mg/m2 |
33.0 |
33.0 |
32.0 |
32.0 |
| PVOH, mg/m2 |
19.0 |
19.0 |
18.4 |
18.4 |
| PAE, mg/m2 |
13.7 |
13.7 |
13.3 |
13.3 |
| Modifier, mg/m2 |
0.3 |
0.3 |
0.3 |
0.3 |
| Reel Moisture, % |
2.8 |
2.5 |
2.5 |
2.8 |
| Post TAD No. 2 Moisture, % |
17.7 |
17.3 |
17.7 |
17.7 |
| Table 3-3 |
| Physical Property Data -TAPPI Conditioned |
| Properties |
R-1 |
R-2 |
R-3 |
R-4 |
| Prototype Description |
Med. Strength/ Low Weight |
Low Strength/ Low Weight |
Med. Strength/ Medium Weight |
Med. Strength/ High Weight |
| Parent Roll Nos. |
15-16 |
27 & 29 |
10-11 |
13 & 15 |
| Date Made |
3/13/2007 |
3/13/2007 |
3/14/2007 |
3/14/2007 |
| Basis Weight. Ib/rm (cond.) |
16.20 |
16.46 |
17.89 |
19.52 |
| Caliper, mils/8 sheets |
108.2 |
116.0 |
110.0 |
113.7 |
| MDT, g/3" |
2123 |
1625 |
2212 |
2127 |
| CDT, g/3" |
2313 |
1763 |
2215 |
2302 |
| GMDT, g/3" |
2216 |
1692 |
2213 |
2211 |
| MDST, % |
18.44 |
19.58 |
20.65 |
20.51 |
| CDST, % |
7.04 |
6.61 |
6.78 |
6.66 |
| Tensile Ratio |
0.92 |
0.92 |
1.00 |
0.93 |
| GMBk Mod, g/% |
196.55 |
148.54 |
188.03 |
190.96 |
| CWDT-Finch, g/3" |
614.7 |
550.7 |
722.6 |
668.8 |
| Wet/Drv Ratio.% |
0.27 |
0.31 |
0.33 |
0.29 |
| SAT (2-ply), g/m2 |
595.2 |
611.6 |
605.3 |
619.9 |
Example 4
[0081] Seven TAD towel base sheets from the previous two Examples were converted to two-ply
finished products. The trial prototypes were produced at a sheet length of 11 inches
and a sheet count of 56.
[0082] The trial prototypes were produced on a commercial towel winder using the nested
emboss pattern shown in
Figures 3A and
3B. Emboss penetration was adjusted to produce a product having a caliper of approximately
240 mils/8 sheets. The same emboss settings were used to produce all seven trial prototypes.
Roll diameter was not controlled; however all trial prototypes had diameters of approximately
5.3 inches. The winding tension was set to deliver rolls having a compression of approximately
seven percent. The trial products were produced at a speed of 1000 fpm. The settings
for the converting line are shown in Table 4-1.
| Table 4-1 |
| Converting Line Settings |
| Emboss Nip Top Roll (inches) |
1.75 |
| Emboss Nip Bottom Roll (inches) |
1.75 |
| Marrving Roll Nip (inches) |
0.5625 |
| Top Rubber Roll Durometer (Shore A) |
56 |
| Bottom Rubber Roll Durometer (Shore A) |
52 |
| Draw Roll Gap (inches) |
0.035 |
| Line Speed (fpm) |
1000 |
[0083] In addition to the prototypes produced at a sheet length of 11 inches, one of the
base sheets (Q1) was converted to finished product at a sheet length of 10 inches.
The towel products were tested for standard physical properties while sensory softness
was measured by a trained panel. The results of these tests are shown in Table 4-2.
| Table 4-2 |
| Physical Properties, Fiber Properties, and Paired HUT Results |
| Product (Base Sheet Cell) |
PH 66.3 (Q2) |
PH73.1 (R4) |
PH68.3 (Q4) |
PH65.3 (Q1) |
PH72.1 (R3) |
PH71.1 (R2) |
PH70.1 (R1) |
PH65.1 (Q1) |
"B" (Market Leading Brand) |
| Basis Weight (lbs/ream) |
35.95 |
36.05 |
36.16 |
33.31 |
33.26 |
30.04 |
30.27 |
34.11 |
27.70 |
| Caliper (mils/8 sheets) |
238.4 |
243.0 |
245.0 |
235.8 |
240.4 |
235.7 |
242.1 |
220.6 |
192.7 |
| MD Tensile (g/3") |
2493 |
3424 |
4784 |
2684 |
3390 |
2415 |
3031 |
3025 |
3045 |
| CD Tensile (g/3") |
1877 |
2585 |
3437 |
2093 |
2490 |
1961 |
2547 |
2458 |
2122 |
| GM Tensile (g/3") |
2162 |
2974 |
4053 |
2368 |
2904 |
2175 |
2777 |
2726 |
2540 |
| MD Stretch (%) |
14.6 |
14.4 |
16.2 |
13.8 |
14.5 |
12.8 |
12.9 |
16.4 |
16.2 |
| CD Stretch (%) |
7.8 |
8.3 |
7.6 |
7.8 |
8.2 |
8.2 |
8.0 |
7.3 |
14.1 |
| CD Wet Tensile - Finch (g/3") |
578 |
755 |
1053 |
609 |
711 |
555 |
792 |
693 |
687 |
| CD Wet/Dry - Finch (%) |
30.8 |
29.2 |
30.7 |
29.2 |
28.6 |
28.4 |
31.1 |
28.1 |
32.4 |
| Perf Tensile (g/3") |
606 |
908 |
1196 |
726 |
893 |
706 |
888 |
730 |
769 |
| SAT Capacity (g/m2) |
512 |
537 |
536 |
506 |
522 |
503 |
527 |
512 |
565 |
| SAT Capacity (g/g) |
8.7 |
9.1 |
9.1 |
9.3 |
9.6 |
10.3 |
10.7 |
9.2 |
12.5 |
| SAT Rate (g/sec0.5) |
0.20 |
0.26 |
0.24 |
0.25 |
0.23 |
0.26 |
0.25 |
0.24 |
0.18 |
| GM Break Modulus (g/%) |
204.1 |
277.9 |
369.1 |
229.3 |
266.9 |
211.7 |
275.5 |
249.4 |
172.3 |
| GM Tensile Modulus (g/in/%) |
47.0 |
60.4 |
73.8 |
50.5 |
58.2 |
49.7 |
61.2 |
48.0 |
43.9 |
| Roll Diameter (inches) |
5.24 |
5.31 |
5.32 |
5.27 |
5.31 |
5.27 |
5.32 |
5.09 |
4.89 |
| Roll Compression (%) |
7.3 |
7.1 |
7.6 |
8.1 |
7.5 |
8.2 |
6.6 |
9.6 |
10.4 |
| Sensory Softness |
6.54 |
5.69 |
4.12 |
5.91 |
4.98 |
5.80 |
4.18 |
6.37 |
7.91 |
| Fiber Properties |
|
|
|
|
|
|
|
|
|
| Ln (mm) |
0.34 |
0.36 |
0.35 |
0.33 |
0.31 |
0.31 |
0.31 |
0.33 |
0.62 |
| Lw (mm) |
1.31 |
1.50 |
1.36 |
1.27 |
1.37 |
1.37 |
1.32 |
1.29 |
1.41 |
| Lz (mm) |
2.31 |
2.54 |
2.36 |
2.26 |
2.44 |
2.44 |
2.36 |
2.26 |
2.16 |
| Coarseness (mg/100m) |
12.05 |
15.24 |
12.54 |
12.53 |
12.87 |
12.76 |
12.92 |
12.17 |
10.95 |
| C/Lz (mg/100m/mm) |
5.23 |
6.00 |
5.32 |
5.54 |
5.28 |
5.23 |
5.48 |
5.38 |
5.07 |
| Fines (num %) |
70.88 |
72.86 |
70.88 |
72.14 |
76.53 |
76.12 |
76.03 |
71.70 |
38.15 |
| Fines (wt %) |
16.25 |
16.39 |
16.01 |
17.55 |
19.78 |
19.43 |
20.08 |
17.03 |
4.83 |
| Paired HUT Results |
|
|
|
|
|
|
|
|
|
| Number of Respondents |
322 |
322 |
333 |
302 |
322 |
314 |
309 |
302 |
-- |
| Preferred Prototype (%) |
57 |
57 |
44 |
48 |
51 |
45 |
44 |
48 |
-- |
| No Preference (%) |
19 |
13 |
11 |
22 |
14 |
21 |
14 |
22 |
-- |
| Preferred Market Leader "B" (%) |
24 |
30 |
44 |
30 |
35 |
34 |
42 |
30 |
-- |
[0084] From the table, the benefit of increased basis weight in obtaining softness can be
seen. Products PH 73.1, PH 72.1, and PH 70.1 have similar (dry) strength values and
were made from similar furnish blends. However, the results of the testing of the
products' softness by a trained panel demonstrate that the sensory softness increases
with increasing basis weight. Even though the prototype having the highest basis weight
of these three towels (PH73.1) has (directionally) higher strength, higher fiber coarseness,
and higher C/Lz (all generally detrimental to softness), it has better softness than
the lower-weight products.
[0085] The prototypes whose data are shown in Table 9-3 were tested in paired Home Use Tests
against towel product "B", the current market leader, which is made of premium fiber
including about 40 percent eucalyptus. It was found that all of the prototypes scored
at least equal to, and, in most cases, better than, product "B". This consumer preference
for the products of the present invention, despite their higher coarseness and C/L
z values, is considered quite surprising in view of B's advantage in some physical
properties and softness. The data also show surprising degree of influence of basis
weight (higher is better) and softness (higher is better) on preference scores.
Example 5
[0086] Prototype base sheets for premium 2-ply TAD towels were prepared having different
levels of strength and softness to be used in forming prototype finished premium 2-ply
TAD towel having superior softness as well as more easily measured physical attributes
(such as thickness, strength and absorbency) for evaluation in home-use testing against
Bounty®, a leading competitive TAD product made from a premium furnish having a basis
weight of 27.5 lb/rm with 40% eucalyptus. Prototypes were manufactured at 36 lb/rm
in low and intermediate strengths. 36 lb/rm prototypes were prepared, at a moderate
wet strength level (CDWT ∼ 550-600 g/3") and a stronger variant at (CDWT ∼650-700
g/3"). After converting the basesheets were used to prepare 56-count ∼5.3" diameter
rolls of standard kitchen roll towel width of 11.0".
[0087] A TAD machine having the configuration shown in Figure 2 with a 3-layer stratified
headbox produced towel basesheets using a furnish of 70% fiber blend B2, a 100% softwood
Kraft and 30% of fiber blend B1, each having the fiber properties set forth in Table
5-1:
| Table 5-1 |
| ID |
number weighted fiber length Ln (mm) |
length weighted fiber length Lw (mm) |
weight weighted fiber length Lz (mm) |
Number % Fines Fn |
Weight % Fines Fw |
Coarseness C mg/100m |
C/Lz |
Nf/g Millions of fibers per gram |
| B 1 |
0.36 |
0.92 |
1.62 |
53.6 |
13.80 |
15.2 |
9.38 |
18.5 |
| B2 |
0.78 |
2.25 |
2.94 |
53.3 |
6.46 |
16.2 |
5.49 |
8.0 |
| Blend |
0.57 |
1.83 |
2.73 |
53.5 |
8.76 |
15.8 |
5.80 |
11.1 |
[0088] The coarseness of a blend of fibers can be determined using the formula:

[0089] These products were produced without use of any retention aid. The prototypes were
produced using an Albany 44G - standard warp through-drying fabric at 17.9% contact
area. The jet-to-wire ratio was adjusted to maintain an MD/CD Tensile Ratio of about
1.0. After the machine was stabilized, the basis weight and refining were adjusted
to produce a 19.3 lb/rm basesheet at a strength level of 475 g/3" CDWT. Thereafter,
the basis weight and refining were adjusted to produce a 19.3 lb/rm basesheet at a
strength level of 560 g/3" CDWT. Polyaminoamide epichlorohydrin permanent wet strength
resin and carboxymethylcellulose were added in the wet-end at levels adjusted as needed
to achieve the desired basesheet tensile strength and wet/dry ratio targets. Headbox
pH was maintained at 7 to 8 while headbox charge was monitored to insure that the
charge is between 0 and -0.30 ml of 10-3 N titer/10 ml solution (-0.030 meq per ml)
to ensure that wet strength resin retention was acceptable. For one of the prototypes,
Hercules TQ-456, an imidazolinium-based debonder containing a poly-propylene glycol
oleate was added to the outlet of the middle and air-side blend chest pumps to achieve
an improved wet-over-dry tensile level. For this prototype, refining was adjusted
to produce a basesheet with a CDWT level of strength approximately 550 g/3". Throughout
the trials, line crepe (approximately fabric crepe plus reel crepe) was maintained
in the neighborhood of 20-22% with the reel crepe being generally held to less than
3% and in most cases, less than 1 or 2%. The basesheets were dried to about 85% solids
on the through-dryer while the reel moisture was maintained at less than about 3.0%.
[0090] Basesheets having the properties set forth in Table 5-2 were produced:
| Table 5-2 |
| Base Sheet Physical Properties |
| Base Sheet ID |
S2 |
S3 |
S4 |
| Used in Prototypes |
W855.1 |
W856.1 W856.2 |
W857.1 |
| Basis Weight (lbs/ream) |
19.42 |
19.66 |
19.54 |
| Caliper (mils/8 sheets) |
117.5 |
116.6 |
116.5 |
| MD Tensile (g/3") |
1631 |
1936 |
1754 |
| CD Tensile (g/3") |
1718 |
1958 |
1693 |
| GM Tensile (g/3") |
1673 |
1945 |
1722 |
| MD Stretch (%) |
28.7 |
29.6 |
28.8 |
| CD Stretch (%) |
7.4 |
7.4 |
7.2 |
| CD Wet Tensile - Finch (g/3") |
462 |
564 |
544 |
| CD Wet/Dry - Finch (%) |
26.9 |
28.8 |
32.1 |
| SAT Capacity (g/sq meter) |
631 |
641 |
598 |
| SAT Capacity (g/g) |
10.0 |
10.0 |
9.4 |
| SAT Rate (g/sec0.5) |
0.32 |
0.34 |
0.22 |
| GM Break Modulus (g/%) |
115.3 |
131.4 |
119.9 |
[0091] TAD towel prototypes were produced from three trial base sheets S2, S3 and S4 as
described above at 56 sheet count in a sheet length of 10.5 inches. The S3 base sheet
was also converted to a product having a sheet length of 11.0 inches.
[0092] The trial prototypes were produced using the nested Emboss pattern shown in
Figures 3A and
3B using new rubber backing and marrying rolls having hardnesses of 60 - 62 Shore A,
and 90 - 95 Shore A, respectively. The converting line's feed rolls were set at gaps
of 35 mils. Emboss penetration was increased until the targeted caliper of approximately
240 mils/8 sheets was obtained. The emboss settings as shown in Table 5-3 were used
to produce finished product rolls at a speed of 1200 fpm. Products produced from the
S3 higher-strength base sheet had higher-than-expected wet tensile values, due to
lower-than-expected breakdowns during the embossing process.
| Table 5-3 |
| Emboss Roll Settings |
| Roll |
Emboss Nip Width (inches) |
| Upper Emboss |
1.25 |
| Lower Emboss |
1.625 |
| Marrying |
0.50 |
[0093] Finished products were tested for standard physical properties while sensory softness
values of the prototypes were measured by a trained panel with the results being as
shown in Table 5-4. Trial data are also illustrated in
Figures 5 and
6 which also presents results from previous trials of similar product as a reference.
In sensory softness measured on this scale, a difference of about 8 pts can typically
be considered statistically significant.
| Table 5-4 |
| Finished Product Physical Properties |
| Product ID |
W855.1 |
W856.1 |
W856.2 |
W857.1 |
| Base Sheet ID |
S2 |
S3 |
S3 |
S4 |
| Product Description |
Low Strength 10.5" |
High Strength 10.5" |
High Strength 11.0" |
High Strength Deb 10.5" |
| Basis Weight (lbs/ream) |
35.82 |
36.82 |
36.95 |
36.27 |
| Caliper (mils/8 sheets) |
238.1 |
235.7 |
233.1 |
234.2 |
| MD Tensile (g/3") |
2622 |
3511 |
3465 |
3129 |
| CD Tensile (g/3 ") |
2220 |
2881 |
2881 |
2340 |
| GM Tensile (g/3") |
2412 |
3180 |
3159 |
2705 |
| MD Stretch (%) |
21.8 |
22.8 |
23.0 |
21.0 |
| CD Stretch (%) |
9.1 |
9.0 |
8.9 |
8.8 |
| CD Wet Tensile - Finch (g/3") |
603 |
803 |
800 |
716 |
| CD Wet/Dry - Finch (%) |
30.8 |
29.2 |
30.7 |
29.2 |
| Perf Tensile (g/3") |
493 |
654 |
640 |
620 |
| SAT Capacity (g/sq meter) |
564 |
566 |
575 |
519 |
| SAT Capacity (g/g) |
9.7 |
9.4 |
9.6 |
8.8 |
| SAT Rate (g/sec^0.5) |
0.32 |
0.32 |
0.34 |
0.24 |
| GM Break Modulus (g/%) |
172.1 |
222.5 |
220.0 |
199.0 |
| GM Tensile Modulus (g/in/%) |
37.0 |
46.4 |
46.6 |
41.2 |
| Macbeth 3100 Brightness |
82.3 |
79.8 |
80.1 |
80.8 |
| Macbeth 3100 L* |
95.2 |
95.0 |
95.1 |
95.2 |
| Macbeth 3100 a* |
-0.9 |
-1.1 |
-1.1 |
-1.1 |
| Macbeth 3100 b* |
4.7 |
6.2 |
6.2 |
5.8 |
| Roll Diameter (inches) |
5.16 |
5.15 |
5.23 |
5.15 |
| Roll Compression (%) |
8.3 |
8.5 |
8.1 |
9.0 |
| Sheet Count |
56 |
56 |
56 |
56 |
| Sheet Length (inches) |
10.53 |
10.52 |
11.00 |
10.48 |
| Sheet Width (inches) |
11.05 |
11.03 |
11.06 |
11.03 |
| Sensory Softness |
7.36 |
6.60 |
6.66 |
7.08 |
[0094] Both SAT capacity and softness of W855.1 were unexpectedly high, while the absorbency
and softness values of W856.1 and W856.2 were slightly higher than expected with wet
strengths that were considerably higher than the expected wet strength of 650 g/3".
[0095] Prototype W857.1 made using the "S4" base sheet, having debonder added at the wet
end, exhibited both reduced SAT capacity and rate but also showed an unexpectedly
low wet/dry ratio, even though its base sheet wet/dry ratio (see Table 5-2 above)
was substantially higher than that of the "S3" base sheet suggesting that use of debonder
was in this instance counterproductive, even though small amounts can be tolerated.
[0096] One of the product prototypes, Cell W856.2, made using the S3 base sheet, was tested
in a Paired HUT vs. "B" the current market leading brand which uses a premium fiber
blend. The results show that the product of the invention is preferred to "B", despite
its fiber disadvantage.
| Table 5-5 |
| Physical Properties, Fiber Properties, and Paired HUT Results |
| Product |
W856.1 |
"B" |
| Basis Weight (lbs/ream) |
36.82 |
27.70 |
| Caliper (mils/8 sheets) |
235.7 |
192.7 |
| MD Tensile (g/3") |
3511 |
3045 |
| CD Tensile (g/3") |
2881 |
2122 |
| GM Tensile (g/3") |
3180 |
2540 |
| MD Stretch (%) |
22.8 |
16.2 |
| CD Stretch (%) |
9.0 |
14.1 |
| CD Wet Tensile - Finch (g/3") |
803 |
687 |
| CD Wet/Dry - Finch (%) |
29.2 |
32.4 |
| Perf Tensile (g/3") |
654 |
769 |
| SAT Capacity (g/m2) |
566 |
565 |
| SAT Capacity (g/g) |
9.4 |
12.5 |
| SAT Rate (g/sec0.5) |
0.32 |
0.18 |
| GM Break Modulus (g/%) |
222.5 |
172.3 |
| GM Tensile Modulus (g/in/%) |
46.4 |
43.9 |
| Roll Diameter (inches) |
5.15 |
4.89 |
| Roll Compression (%) |
8.5 |
10.4 |
| Sensory Softness |
6.60 |
7.91 |
| Fiber Properties |
|
|
| Ln (mm) |
0.49 |
0.62 |
| Lw (mm) |
1.66 |
1.41 |
| Lz (mm) |
2.58 |
2.16 |
| Coarseness (mg/100m) |
15.55 |
10.95 |
| C/Lz (mg/100m/mm) |
6.03 |
5.07 |
| Fines (num %) |
58.11 |
38.15 |
| Fines (wt %) |
10.53 |
4.83 |
| Paired HUT Results |
|
|
| Number of Respondents |
319 |
-- |
| Preferred Prototype (%) |
57 |
-- |
| No Preference (%) |
18 |
-- |
| Preferred "B" (%) |
26 |
-- |
Example 6
[0097] In the course of consumer testing of the product of the present invention, it was
noticed that consumers perceived the softness of these towels as considerably softer
than would have normally been predicted when subjected to softness evaluation by sensory
panels. This example compares the consumer softness of the product of the invention
vs. the consumer softness of other products having similar (± 1) panel softness. The
data in Table 6-1 show that the invention receives a higher consumer softness rating
than would be expected from the panel softness rating. Until recognized, this surprising
and unexpected effect greatly hampered efforts to produce the towels of the present
invention.
| Table 6-1 |
| Softness Ratings of Towel Products |
| Product |
Basis Weight (lbs/ream) |
Caliper (mils/8 sheets) |
Panel Softness |
Monadic HUT Softness (0 - 100) |
| Invention |
36.7 |
239.8 |
7.88 |
76 |
| A |
29.4 |
188.9 |
7.60 |
70 |
| W |
29.1 |
194.6 |
7.46 |
68 |
| C |
26.7 |
212.8 |
7.27 |
72 |
| D |
25.5 |
185.9 |
8.87 |
76 |
| E |
23.9 |
198.9 |
8.01 |
68 |
| F |
25.6 |
180.0 |
8.74 |
67 |
Example 7
[0098] This example compares a product of the invention to other commercially available
products that have approximately the same strength. Even though the competitive products
have better fiber (lower C/L
z), the product of the invention has equal or higher softness.
| Table 7-1 |
| Properties of Towel Products |
| Product |
Current Invention |
Competitive Product X |
Competitive Product Y |
| Basis Weight (lbs/ream) |
36.82 |
28.77 |
25.8 |
| Caliper (mils/8 sheets) |
235.7 |
163.4 |
163.3 |
| MD Tensile (g/3") |
3511 |
4059 |
3439 |
| CD Tensile (g/3") |
2881 |
2279 |
2524 |
| GM Tensile (g/3") |
3180 |
3039 |
2945 |
| MD Stretch (%) |
22.8 |
13.5 |
14.2 |
| CD Stretch (%) |
9.0 |
8.0 |
9.6 |
| CD Wet Tensile - Finch (g/3") |
803 |
532 |
553 |
| CD Wet/Dry - Finch (%) |
29.2 |
23.4 |
21.9 |
| Perf Tensile (g/3") |
654 |
766 |
872 |
| SAT Capacity (g/m2) |
566 |
382 |
339 |
| SAT Capacity (g/g) |
9.4 |
8.2 |
8.1 |
| SAT Rate (g/sec0.5) |
0.32 |
0.18 |
0.17 |
| GM Break Modulus (g/%) |
222.5 |
292.5 |
251 |
| GM Tensile Modulus (g/in/%) |
46.4 |
50.0 |
51 |
| Roll Diameter (inches) |
5.15 |
5.05 |
5.0 |
| Roll Compression (%) |
8.5 |
19.2 |
26.0 |
| Sensory Softness |
6.60 |
6.43 |
5.10 |
| Ln (mm) |
0.49 |
0.65 |
0.55 |
| Lw (mm) |
1.66 |
2.19 |
1.82 |
| Lz (mm) |
2.58 |
2.82 |
2.63 |
| Coarseness (mg/100m) |
15.55 |
13.97 |
13.05 |
| C/Lz (mg/100m/mm) |
6.03 |
4.95 |
4.96 |
| Fines (num %) |
58.11 |
61.11 |
58.54 |
| Fines (wt %) |
10.53 |
7.31 |
9.08 |
Example 8
[0099] Two base sheets were produced in a similar manner to that described in Example 2
from a furnish made up of 70% SWK, 30% HWK that included 30% Broke. For one of the
base sheets, the layer next to the Yankee dryer contained 100% SWK; the other base
sheet had a Yankee-side layer composed of a 50/50 blend of SWK and HWK. The base sheet
physical properties are shown in Table 8-1.
| Table 8-1 |
| Base Sheet Physical Properties |
| Yankee Layer Stratification |
100% SWK |
50/50 SWK/ HWK |
| Basis Weight (lbs/ream) |
19.61 |
19.44 |
| Caliper (mils/8 sheets) |
115.5 |
111.1 |
| MD Tensile (g/3") |
1567 |
1699 |
| CD Tensile (g/3 ") |
1526 |
1714 |
| GM Tensile (g/3") |
1544 |
1707 |
| Tensile Ratio |
1.03 |
0.99 |
| MD Stretch (%) |
21.4 |
23.0 |
| CD Stretch (%) |
7.5 |
7.6 |
| CD Wet Tensile - Finch (g/3") |
436 |
508 |
| CD Wet/Dry - Finch (%) |
28.6 |
29.7 |
| SAT Capacity (g/sq meter) |
647 |
632 |
| SAT Capacity (g/g) |
10.14 |
9.98 |
| SAT Rate (g/sec^0.5) |
0.35 |
0.31 |
| GM Break Modulus (g/%) |
123.7 |
130.4 |
| GM Tensile Modulus (g/in/%) |
38.9 |
36.4 |
[0100] Fiber counts of both base sheets were performed to determine the actual fiber stratification
of the towels. Table 8-2 shows the results of these counts, both of a composite sample
and of the individual layers. The test results show that, though the overall fiber
composition of the two sheets is quite similar, the distribution of the fibers within
the sheet is very different, with the base sheet having all SWK placed in the Yankee
layer having a much higher percentage of that fiber in Layer 1, the Yankee-side layer.
| Table 8-2 |
| Fiber Analysis of Towel Base Sheets |
| Yankee Layer Stratification |
100% SWK |
50/50 SWK/HWK |
| Fiber Composition (% SWK/% HWK) |
|
|
| Total Sheet |
57.9/42.1 |
56.9/43.1 |
| Layer 1 (Yankee Layer) |
86.0/14.0 |
51.1/48.9 |
| Layer 3 |
80.3/19.7 |
53.0/47.0 |
| Layer 6 |
44.8/55.2 |
47.4/52.6 |
| Layer 8 |
27.3/72.7 |
63.7/36.3 |
[0101] Both base sheets were converted to two-ply finished product using the emboss pattern
shown in
Figures 3A and
3B. The products were produced such that the Yankee layers of the base sheet were on
the outside of the towel product. The embossing conditions used to produce the towels
are shown in Table 8-3
| Table 8-3: Embossing Conditions |
| Emboss Parameter |
Value |
| Upper Rubber Roll Diameter |
19.5 inches |
| |
(0.625" thick rubber covering) |
| Upper Steel Emboss Roll Diameter |
20 inches |
| Upper Rubber Roll Hardness |
45 Shore A (Dual Durometer) |
| Upper Embosser Nip Width |
1-13/16 inch |
| Lower Rubber Roll Diameter |
19.5 inches |
| |
(0.625" thick rubber covering) |
| Lower Steel Emboss Roll Diameter |
20 inches |
| Lower Rubber Roll Hardness |
45 Shore A (Dual Durometer) |
| Lower Embosser Nip Width |
1-13/16 inch |
| Marrying Roll Diameter |
14 inches |
| Marrying Roll Rubber Hardness |
90 Shore A (spec) |
| Marrying Roll Nip Width |
5/8 inch |
| Draw Roll Gaps - Infeed/Outfeed |
0.035 / 0.035 inch |
| |
|
| Rewinder Parameters |
|
| #1 Unwind Tension |
14 lbs |
| #2 Unwind Tension |
14 lbs |
| Rewinder Tension |
4 lbs |
| Enveloping Roll |
-0.90 draw |
| Perforator |
-0.92 draw |
| Speed |
777 fpm |
[0102] The physical properties of the two towel prototypes are shown in the Table 8-4 below.
| Table 8-4 |
| Product Physical Properties |
| Yankee Layer Stratification |
100% SWK |
50/50 SWK/ HWK |
| Basis Weight (lbs/ream) |
37.11 |
36.40 |
| Caliper (mils/8 sheets) |
228.7 |
227.1 |
| MD Tensile (g/3") |
2680 |
2825 |
| CD Tensile (g/3") |
2047 |
2297 |
| GM Tensile (g/3") |
2341 |
2546 |
| Tensile Ratio |
1.31 |
1.23 |
| MD Stretch (%) |
18.6 |
16.7 |
| CD Stretch (%) |
8.0 |
8.2 |
| CD Wet Tensile - Finch (g/3") |
609 |
638 |
| CD Wet/Dry - Finch (%) |
29.8 |
27.8 |
| Perf Tensile (g/3") |
936 |
1068 |
| SAT Capacity (g/sq meter) |
545 |
520 |
| SAT Capacity (g/g) |
9.02 |
8.78 |
| SAT Rate (g/sec^0.5) |
0.25 |
0.23 |
| GM Break Modulus (g/%) |
192.0 |
216.5 |
| GM Tensile Modulus (g/in/%) |
40.8 |
49.0 |
| Roll Diameter (inches) |
4.90 |
4.93 |
| Roll Compression (%) |
8.6 |
9.0 |
| Sensory Softness |
7.83 |
7.46 |
[0103] Both prototypes had similar physical properties and good softness values. However,
finished products made from the base sheet having the 50/50 SWK/HWK blend in the Yankee-side
layer produced more dust and lint during the converting process than did the prototype
made using the base sheet whose Yankee layer was composed of 100% SWK. This dust required
cleaning at intervals to remove dust from the converting lines. Base sheet made using
the sheet having 100% SWK in the Yankee layer was converted without these issues.
Example 9
[0104] A towel base sheet was produced on a TAD paper machine in a manner similar to that
described in Example 2. The overall furnish was composed of a 70/30 blend of SWK/HWK
and included 30% broke. The physical properties of the base sheet are shown in Table
9-1.
| Table 9-1 |
| Base Sheet Physical Properties |
| Basis Weight (lbs/ream) |
19.73 |
| Caliper (mils/8 sheets) |
114.2 |
| MD Tensile (g/3") |
1602 |
| CD Tensile (g/3") |
1694 |
| GM Tensile (g/3") |
1645 |
| Tensile Ratio |
0.95 |
| MD Stretch (%) |
23.3 |
| CD Stretch (%) |
6.6 |
| CD Wet Tensile - Finch (g/3") |
441 |
| CD Wet/Dry - Finch (%) |
26.0 |
| SAT Capacity (g/sq meter) |
603 |
| SAT Capacity (g/g) |
9.40 |
| SAT Rate (g/sec^0.5) |
0.26 |
| GM Break Modulus (g/%) |
134.1 |
| GM Tensile Modulus (g/in/%) |
35.3 |
[0105] The base sheet was embossed using the emboss pattern shown in
Figures 3A and
3B. Finished products were produced at four levels of emboss, as shown in Table 9-2.
| Table 9-2 |
| Emboss Nip Widths - Penetration Curve Samples |
| Marrying Roll (all cells) |
5/8 inch |
| Condition 1A |
|
| Upper Embosser |
1-13/16 inch |
| Lower Embosser |
1-13/16 inch |
| Condition 1B |
|
| Upper Embosser |
1-15/16 inch |
| Lower Embosser |
1-15/16 inch |
| Condition 1C |
|
| Upper Embosser |
1-5/8 inch |
| Lower Embosser |
1-3/4 inch |
| Condition 1D |
|
| Upper Embosser |
1-1/2 inch |
| Lower Embosser |
1-11/16 inch |
[0106] The physical properties of the finished products produced are shown in Table 9-3.
| Table 9-3 |
| Penetration Curve Samples |
| Product |
Cell 1A |
Cell 1B |
Cell 1C |
Cell 1D |
| Basis Weight (lbs/ream) |
36.83 |
36.95 |
37.33 |
37.69 |
| Caliper (mils/8 sheets) |
225.5 |
229.2 |
212.3 |
209.8 |
| MD Tensile (g/3") |
3183 |
2908 |
3374 |
3433 |
| CD Tensile (g/3") |
2389 |
2121 |
2824 |
3003 |
| GM Tensile (g/3") |
2757 |
2483 |
3084 |
3210 |
| Tensile Ratio |
1.33 |
1.37 |
1.19 |
1.14 |
| MD Stretch (%) |
16.1 |
15.8 |
17.5 |
18.4 |
| CD Stretch (%) |
8.0 |
8.3 |
7.6 |
7.7 |
| CD Wet Tensile - Finch (g/3") |
658 |
594 |
810 |
834 |
| CD Wet/Dry - Finch (%) |
27.5 |
28.0 |
28.7 |
27.8 |
| Perf Tensile (g/3") |
1044 |
1185 |
824 |
1264 |
| SAT Capacity (g/sq meter) |
508 |
526 |
514 |
518 |
| SAT Capacity (g/g) |
8.47 |
8.75 |
8.45 |
8.44 |
| SAT Rate (g/sec^0.5) |
0.22 |
0.22 |
0.21 |
0.22 |
| GM Break Modulus (g/%) |
242.3 |
215.2 |
266.5 |
266.9 |
| GM Tensile Modulus (g/in/%) |
50.6 |
46.1 |
56.5 |
54.3 |
| Roll Diameter (inches) |
4.94 |
4.93 |
4.89 |
4.90 |
| Roll Compression (%) |
9.8 |
7.9 |
12.9 |
13.3 |
| Sensory Softness |
7.36 |
7.48 |
7.00 |
6.75 |
[0107] Examination of the finished product data shows that, as expected, the caliper of
the product increased with increasing emboss penetration. This finding is illustrated
in
Figure 6. In the figure, the emboss penetration values have been translated to an embossing
pressure, expressing in pounds/lineal inch (PLI). Surprisingly, however, the towel's
absorption capacity (as measured by the simple absorption test - SAT) declined with
increasing emboss penetration until a certain level of emboss was reached, at which
point the absorption capacity of the product increased. This finding is illustrated
in
Figure 7. Figure 8 combines the results of
Figures 6 and 7, illustrating the surprising relationship between absorbency and caliper.