U.S. patent application number 12/902175 was filed with the patent office on 2011-04-21 for fibrous structures comprising non-naturally occurring hardwood pulp fibers.
Invention is credited to Dale Gary Kavalew, Osman Polat.
Application Number | 20110088858 12/902175 |
Document ID | / |
Family ID | 43063680 |
Filed Date | 2011-04-21 |
United States Patent
Application |
20110088858 |
Kind Code |
A1 |
Polat; Osman ; et
al. |
April 21, 2011 |
FIBROUS STRUCTURES COMPRISING NON-NATURALLY OCCURRING HARDWOOD PULP
FIBERS
Abstract
Fibrous structures employing non-naturally occurring hardwood
pulp fibers, and more particularly, sanitary tissue products
employing non-naturally occurring hardwood pulp fibers and methods
for making same are provided.
Inventors: |
Polat; Osman; (Montgomery,
OH) ; Kavalew; Dale Gary; (Evendale, OH) |
Family ID: |
43063680 |
Appl. No.: |
12/902175 |
Filed: |
October 12, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61252394 |
Oct 16, 2009 |
|
|
|
Current U.S.
Class: |
162/91 ;
162/202 |
Current CPC
Class: |
D21H 27/005 20130101;
D21H 27/002 20130101; D21C 5/005 20130101; D21H 17/005
20130101 |
Class at
Publication: |
162/91 ;
162/202 |
International
Class: |
D21C 3/00 20060101
D21C003/00; D21F 11/02 20060101 D21F011/02 |
Claims
1. A fibrous structure comprising a non-naturally occurring
hardwood pulp fiber that exhibits a handsheet tensile strength as
measured according to the Handsheet Tensile Strength Test Method
described herein less than the handsheet tensile strength of the
non-naturally occurring hardwood pulp fiber in its naturally
occurring state.
2. The fibrous structure according to claim 1 wherein the
non-naturally occurring hardwood pulp fiber is obtained from a
naturally occurring hardwood pulp fiber.
3. The fibrous structure according to claim 2 wherein the naturally
occurring hardwood pulp fiber is obtained from a fiber source
selected from the group consisting of: Acacia, Eucalyptus, Maple,
Oak, Aspen, Birch, Cottonwood, Alder, Ash, Cherry, Elm, Hickory,
Poplar, Gum, Walnut, Locust, Sycamore, Beech, Catalpa, Sassafras,
Gmelina, Albizia, Anthocephalus, Magnolia, and mixtures
thereof.
4. The fibrous structure according to claim 2 wherein the naturally
occurring hardwood pulp fiber is obtained from Eucalyptus.
5. The fibrous structure according to claim 2 wherein the naturally
occurring hardwood pulp fiber comprises a tropical hardwood pulp
fiber.
6. The fibrous structure according to claim 1 wherein the
non-naturally occurring hardwood pulp fiber is obtained by
enzymatically treating a naturally occurring hardwood pulp
fiber.
7. The fibrous structure according to claim 6 wherein the
non-naturally occurring hardwood pulp fiber is obtained by treating
a naturally occurring hardwood pulp fiber with xylanase.
8. The fibrous structure according to claim 6 wherein the
non-naturally occurring hardwood pulp fiber is obtained by treating
a naturally occurring hardwood pulp fiber with an enzyme
composition comprising xylanase and cellulase.
9. The fibrous structure according to claim 1 wherein the
non-naturally occurring hardwood pulp fiber exhibits a PFR of 7.4
or less.
10. A single- or multi-ply sanitary tissue product comprising one
or more fibrous structures according to claim 1.
11. A sanitary tissue product comprising a non-naturally occurring
hardwood pulp fiber that exhibits a handsheet tensile strength as
measured according to the Handsheet Tensile Strength Test Method
described herein less than the handsheet tensile strength of the
non-naturally occurring hardwood pulp fiber in its naturally
occurring state, wherein the sanitary tissue product exhibits a
greater wet burst strength as measured according to the Wet Burst
Strength Test Method described herein and/or a greater initial
total wet tensile as measured by the Initial Total Wet Tensile Test
Method described herein than a sanitary tissue product that
comprises the non-naturally occurring hardwood pulp fiber in its
naturally occurring state.
12. The sanitary tissue product according to claim 11 wherein the
non-naturally occurring hardwood pulp fiber is obtained from a
naturally occurring hardwood pulp fiber.
13. The sanitary tissue product according to claim 12 wherein the
naturally occurring hardwood pulp fiber is obtained from a fiber
source selected from the group consisting of: Acacia, Eucalyptus,
Maple, Oak, Aspen, Birch, Cottonwood, Alder, Ash, Cherry, Elm,
Hickory, Poplar, Gum, Walnut, Locust, Sycamore, Beech, Catalpa,
Sassafras, Gmelina, Albizia, Anthocephalus, Magnolia, and mixtures
thereof.
14. The sanitary tissue product according to claim 12 wherein the
naturally occurring hardwood pulp fiber is obtained from
Eucalyptus.
15. The sanitary tissue product according to claim 12 wherein the
naturally occurring hardwood pulp fiber comprises a tropical
hardwood pulp fiber.
16. The sanitary tissue product according to claim 11 wherein the
non-naturally occurring hardwood pulp fiber is obtained by
enzymatically treating a naturally occurring hardwood pulp
fiber.
17. The sanitary tissue product according to claim 16 wherein the
non-naturally occurring hardwood pulp fiber is obtained by treating
a naturally occurring hardwood pulp fiber with xylanase.
18. The sanitary tissue product according to claim 16 wherein the
non-naturally occurring hardwood pulp fiber is obtained by treating
a naturally occurring hardwood pulp fiber with an enzyme
composition comprising xylanase and cellulase.
19. The sanitary tissue product according to claim 11 wherein the
non-naturally occurring hardwood pulp fiber exhibits a PFR of 7.4
or less.
20. A method for making a fibrous structure comprising the steps
of: a. providing a fibrous composition comprising a non-naturally
occurring hardwood pulp fiber that exhibits a handsheet tensile
strength as measured according to the Handsheet Tensile Strength
Test Method described herein less than the handsheet tensile
strength of the non-naturally occurring hardwood pulp fiber in its
naturally occurring state; and b. depositing the fibrous
composition onto a collection device to form a fibrous structure.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/252,394 filed Oct. 16, 2009.
FIELD OF THE INVENTION
[0002] The present invention relates to fibrous structures
comprising non-naturally occurring hardwood pulp fibers, and more
particularly, sanitary tissue products comprising non-naturally
occurring hardwood pulp fibers and methods for making same.
BACKGROUND OF THE INVENTION
[0003] Fibrous structures and/or sanitary tissue products
comprising hardwood pulp fibers including non-naturally occurring
hardwood pulp fibers are known in the art. However, the level of
hardwood pulp fibers that formulators have used in their fibrous
structures and/or sanitary tissue products have been limited due to
the fact that hardwood pulp fibers conventionally have not
exhibited the tensile strengths desired by consumers of such
fibrous structures and/or sanitary tissue products. Therefore,
formulators have had to use a mixture of hardwood pulp fibers and
softwood pulp fibers to achieve the tensile strengths needed in
their fibrous structures and/or sanitary tissue products.
[0004] Due to the costs differences between softwood pulp fibers
and hardwood pulp fibers (softwood pulp fibers typically being more
expensive) formulators desire to increase the hardwood pulp fiber
levels and decrease the softwood pulp fiber levels in their fibrous
structures and/or sanitary tissue products. Formulators have not
had success in doing so due to the tensile strength differences
between softwood pulp fibers and conventional hardwood pulp fibers
and the drainage properties (as represented by PFR) of conventional
hardwood pulp fibers.
[0005] It is known that hardwoods increase the softness of the
fibrous structures in which they are present. Therefore, there is a
continuing desire, especially for softer fibrous structures, to
increase the level of hardwood present in fibrous structures.
[0006] Accordingly, there is a need for fibrous structures and/or
sanitary tissue products comprising hardwood pulp fibers that
overcome or at least partially overcome the differences between
softwood pulp fibers and conventional hardwood pulp fibers and/or
that overcome the negatives associated with conventional hardwood
pulp fibers.
SUMMARY OF THE INVENTION
[0007] The present invention fulfills the need described above by
providing fibrous structures and/or sanitary tissue products
comprising hardwood pulp fibers that overcome or at least partially
overcome the differences between softwood pulp fibers and
conventional hardwood pulp fibers and/or that overcome the
negatives associated with conventional hardwood pulp fibers.
[0008] In one example of the present invention, a fibrous structure
comprising a non-naturally occurring hardwood pulp fiber that
exhibits a handsheet tensile strength as measured according to the
Handsheet Tensile Strength Test Method described herein less than
the handsheet tensile strength of the non-naturally occurring
hardwood pulp fiber in its naturally occurring state, is
provided.
[0009] In another example of the present invention, a sanitary
tissue product comprising a non-naturally occurring hardwood pulp
fiber that exhibits a handsheet tensile strength as measured
according to the Handsheet Tensile Strength Test Method described
herein less than the handsheet tensile strength of the
non-naturally occurring hardwood pulp fiber in its naturally
occurring state, wherein the sanitary tissue product exhibits a
greater wet burst strength as measured according to the Wet Burst
Strength Test Method described herein and/or a greater initial
total wet tensile as measured by the Initial Total Wet Tensile Test
Method described herein than a sanitary tissue product that
comprises the non-naturally occurring hardwood pulp fiber in its
naturally occurring state, is provided.
[0010] In yet another example of the present invention, a fibrous
structure comprising an enzyme treated hardwood pulp fiber that
exhibits a handsheet tensile strength as measured according to the
Handsheet Tensile Strength Test Method described herein less than
the handsheet tensile strength of the hardwood pulp fiber without
the enzyme treatment, is provided.
[0011] In still another example of the present invention, a
sanitary tissue product comprising an enzyme treated hardwood pulp
fiber that exhibits a handsheet tensile strength as measured
according to the Handsheet Tensile Strength Test Method described
herein less than the handsheet tensile strength of the non-enzyme
treated hardwood pulp fiber, wherein the sanitary tissue product
exhibits a greater wet burst strength as measured according to the
Wet Burst Strength Test Method described herein and/or a greater
initial total wet tensile as measured by the Initial Total Wet
Tensile Test Method described herein than a sanitary tissue product
that comprises the non-enzyme treated hardwood pulp fiber, is
provided.
[0012] In even yet another example of the present invention, a
method for making a fibrous structure comprising the steps of:
[0013] a. providing a fibrous composition comprising a
non-naturally occurring hardwood pulp fiber that exhibits a
handsheet tensile strength as measured according to the Handsheet
Tensile Strength Test Method described herein less than the
handsheet tensile strength of the non-naturally occurring hardwood
pulp fiber in its naturally occurring state; and [0014] b.
depositing the fibrous composition onto a collection device, such
as a fabric and/or a belt, to form a fibrous structure.
[0015] Accordingly, the present invention provides fibrous
structures and/or sanitary tissue products comprising novel
non-naturally occurring hardwood pulp fibers and method for making
such fibrous structures and/or sanitary tissue products.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
[0016] "Pulp fiber" as used herein means a virgin fiber obtained
from a tree or plant.
[0017] A specific type of pulp fiber is a wood fiber. "Wood fiber"
as used herein means a virgin fiber obtained from a tree.
[0018] Pulp (one or more pulp fibers) may be chemical pulps, such
as kraft (sulfate) and sulfite pulps, as well as mechanical and
semi-chemical pulps including, for example, groundwood,
thermomechanical pulp, chemi-mechanical pulp (CMP),
chemi-thermomechanical pulp (CTMP), neutral semi-chemical sulfite
pulp (NSCS).
[0019] The pulp fibers may be short (typical of hardwood fibers) or
long (typical of softwood fibers).
[0020] "Hardwood pulp fiber" as used herein means pulp fibers
obtained from deciduous trees. Non-limiting examples of deciduous
trees include Northern hardwood trees and tropical hardwood trees.
Non-limiting examples of hardwood pulp fibers include hardwood pulp
fibers obtained from a fiber source selected from the group
consisting of Acacia, Eucalyptus, Maple, Oak, Aspen, Birch,
Cottonwood, Alder, Ash, Cherry, Elm, Hickory, Poplar, Gum, Walnut,
Locust, Sycamore, Beech, Catalpa, Sassafras, Gmelina, Albizia,
Anthocephalus, Magnolia, and mixtures thereof. In one example, the
hardwood pulp fiber of the present invention is obtained from
Eucalyptus.
[0021] "Tropical hardwood pulp fiber" as used herein means pulp
fibers obtained from a tropical hardwood tree. Non-limiting
examples of tropical hardwood trees include Eucalyptus trees and/or
Acacia trees.
[0022] "Naturally occurring hardwood pulp fiber" as used herein
means a pulp fiber that is found in nature or that has only been
subjected to conventional pulping and/or bleaching processes
without the presence of enzymes.
[0023] "Non-naturally occurring hardwood pulp fiber" as used herein
means a naturally occurring hardwood pulp fiber that has been
modified and/or treated by humans through a human-designed process
and/or a human executed modifying and/or treating process. A
naturally occurring hardwood pulp fiber that has been treated with
an enzyme, such as during the pulping process, is a non-naturally
occurring hardwood pulp fiber. In one example, a non-naturally
occurring hardwood pulp fiber is a Eucalyptus pulp fiber that has
been treated with an enzyme composition, for example an enzyme
composition comprising xylanase.
[0024] "Fibrous structure" as used herein means a structure that
comprises one or more pulp fibers. Non-limiting examples of
processes for making fibrous structures include known wet-laid
papermaking processes and air-laid papermaking processes. Such
processes typically include steps of preparing a pulp fiber
composition, oftentimes referred to as a fiber slurry in wet-laid
processes, either wet or dry, and then depositing a plurality of
fibers onto a forming wire or belt such that an embryonic fibrous
structure is formed, drying and/or bonding the fibers together such
that a fibrous structure is formed, and/or further processing the
fibrous structure such that a finished fibrous structure is formed.
For example, in typical papermaking processes, the finished fibrous
structure is the fibrous structure that is wound on the reel at the
end of papermaking, but before converting thereof into a sanitary
tissue product.
[0025] Non-limiting types of fibrous structures according to the
present invention include conventionally felt-pressed fibrous
structures; pattern densified fibrous structures; and high-bulk,
uncompacted fibrous structures. The fibrous structures may be of a
homogeneous or multilayered (two or three or more layers)
construction; and the sanitary tissue products made therefrom may
be of a single-ply or multi-ply construction.
[0026] The fibrous structures may be post-processed, such as by
embossing and/or calendaring and/or folding and/or printing images
thereon.
[0027] The fibrous structures may be through-air-dried fibrous
structures or conventionally dried fibrous structures.
[0028] The fibrous structures may be creped or uncreped.
[0029] The fibrous structures of the present invention may
comprise, in addition to non-naturally occurring hardwood pulp
fibers, naturally occurring pulp fibers, such as naturally
occurring hardwood pulp fibers, naturally occurring softwood pulp
fibers, synthetic fibers and/or filaments, such as polypropylene
filaments, naturally occurring animal fibers, other naturally
occurring plant fibers, and other non-naturally occurring fibers.
The fibers may be in different layers within the fibrous structure
or may be blended together in a single layer.
[0030] "Sanitary tissue product" comprises one or more fibrous
structures, converted or not, that is useful as a wiping implement
for post-urinary and post-bowel movement cleaning (toilet paper),
for otorhinolaryngological discharges (facial tissue and/or
disposable handkerchiefs), and multi-functional absorbent and
cleaning uses (absorbent towels and/or wipes). The sanitary tissue
product may be convolutedly wound upon itself about a core or
without a core to form a sanitary tissue product roll.
[0031] In one example, the sanitary tissue product of the present
invention comprises one or more fibrous structures according to the
present invention.
[0032] The sanitary tissue products of the present invention may
exhibit a basis weight between about 10 g/m.sup.2 to about 120
g/m.sup.2 and/or from about 15 g/m.sup.2 to about 110 g/m.sup.2
and/or from about 20 g/m.sup.2 to about 100 g/m.sup.2 and/or from
about 30 to 90 g/m.sup.2. In addition, the sanitary tissue product
of the present invention may exhibit a basis weight between about
40 g/m.sup.2 to about 120 g/m.sup.2 and/or from about 50 g/m.sup.2
to about 110 g/m.sup.2 and/or from about 55 g/m.sup.2 to about 105
g/m.sup.2 and/or from about 60 to 100 g/m.sup.2.
[0033] The sanitary tissue products of the present invention may be
in the form of sanitary tissue product rolls. Such sanitary tissue
product rolls may comprise a plurality of connected, but perforated
sheets of fibrous structure, that are separably dispensable from
adjacent sheets.
[0034] The sanitary tissue products of the present invention may
comprises additives such as softening agents, temporary wet
strength agents, permanent wet strength agents, bulk softening
agents, lotions, silicones, wetting agents, latexes, patterned
latexes and other types of additives suitable for inclusion in
and/or on sanitary tissue products.
[0035] "Ply" or "Plies" as used herein means an individual finished
fibrous structure optionally to be disposed in a substantially
contiguous, face-to-face relationship with other plies, forming a
multiple ply finished fibrous structure product and/or sanitary
tissue product. It is also contemplated that a single fibrous
structure can effectively form two "plies" or multiple "plies", for
example, by being folded on itself.
[0036] "Wet burst strength" as used herein is a measure of the
ability of a fibrous structure and/or a sanitary tissue product
incorporating a fibrous structure to absorb energy, when wet and
subjected to deformation normal to the plane of the fibrous
structure and/or fibrous structure product.
Non-naturally Occurring Hardwood Pulp Fibers
[0037] The non-naturally occurring hardwood pulp fibers of the
present invention exhibit a handsheet tensile strength as measured
according to the Handsheet Tensile Strength Test Method described
herein less than the handsheet tensile strength of the
non-naturally occurring hardwood pulp fiber in its naturally
occurring state.
[0038] Further, the non-naturally occurring hardwood pulp fibers of
the present invention exhibit the lower handsheet tensile strength
without increasing the PFR of the hardwood pulp fibers as measured
in their naturally occurring state. As a result, the non-naturally
occurring hardwood pulp fibers provide a weaker fiber with respect
to its handsheet tensile strength that dries and/or drains as good
or better, as measured according to the PFR Test Method described
herein, than the same hardwood pulp fibers as measured in their
naturally occurring state.
[0039] Unexpectedly, the non-naturally occurring hardwood pulp
fibers of the present invention, which weaker than their naturally
occurring state, result in a sanitary tissue product comprising
such non-naturally occurring hardwood pulp fibers exhibiting a
greater wet burst strength and/or initial total wet tensile than a
sanitary tissue product comprising the non-naturally occurring
hardwood pulp fibers in their naturally occurring state.
[0040] Table 1 below evidences the differences between the fibrous
structures and/or sanitary tissue products (A-C) comprising the
non-naturally occurring hardwood pulp fibers of the present
invention compared to a fibrous structure and/or sanitary tissue
product (Control) comprising the hardwood pulp fibers in their
naturally occurring state. The non-naturally occurring hardwood
pulp fibers used in A and B were treated with a xylanase. The
non-naturally occurring hardwood pulp fibers used in C were treated
with an enzyme composition comprising xylanase and cellulase.
TABLE-US-00001 TABLE 1 Property Control A B C Handsheet Tensile
Strength 428 353 290 401 (g/in per lb/3,000 ft.sup.2) PFR (s.sup.2)
7.4 7.1 6.9 7.4 Sanitary Tissue Product Wet 418 465 Did not 464
Burst Strength (g) measure Sanitary Tissue Product 56.6 62.6 68.4
65.8 Initial Total Wet Tensile (g/in) Relative Softness compared --
Softer Softer Less soft to Control
[0041] The non-naturally occurring hardwood pulp fibers for use in
the fibrous structures and/or sanitary tissue products of the
present invention may exhibit a PFR of 7.4 or less and/or less than
7.3 and/or less than 7.2 and/or less than 7.1 and/or less than 7.0
to about 0 and/or to about 1 and/or to about 2 as measured
according to the PFR Test Method described herein.
Enzymes
[0042] In one example of the present invention, the non-naturally
occurring hardwood pulp fibers of the present invention may be
derived from enzymatically treating naturally occurring hardwood
pulp fibers. The enzyme and/or enzyme composition useful in
enzymatically treating the naturally occurring hardwood pulp fibers
comprises a xylanase enzyme.
[0043] In one example, the enzyme composition used to enzymatically
treat the naturally occurring hardwood pulp fibers comprises
xylanase and cellulase.
Fibrous Structure
[0044] The fibrous structure of the present invention comprises one
or more non-naturally occurring hardwood pulp fibers that exhibit a
handsheet tensile strength less than the handsheet tensile strength
of the non-naturally occurring hardwood pulp fiber in its naturally
occurring state as measured according to the Handsheet Tensile
Strength Test Method described herein. In one example, the fibrous
structure comprises at least 5% and/or at least 10% and/or at least
20% and/or at least 30% and/or at least 40% to about 100% and/or to
about 90% and/or to about 80% and/or to about 70% and/or to about
60% by weight on a dry fiber basis of non-naturally occurring
hardwood pulp fibers that exhibit a handsheet tensile strength less
than the handsheet tensile strength of the non-naturally occurring
hardwood pulp fiber in its naturally occurring state as measured
according to the Handsheet Tensile Strength Test Method described
herein.
[0045] In addition to the non-naturally occurring hardwood pulp
fibers, the fibrous structures of the present invention may
comprise softwood pulp fibers, such as Northern Softwood Kraft pulp
fibers (NSK). In one example, the fibrous structure comprises from
about 0 to about 90% and/or from about 10 to about 80% and/or from
about 30 to about 70% by weight on a dry fiber basis of softwood
pulp fibers and from about 10 to about 100% and/or from about 20 to
about 90% and/or from about 30 to about 70% by weight on a dry
fiber basis of hardwood pulp fibers at least a portion of which
comprises non-naturally occurring hardwood pulp fibers that exhibit
a handsheet tensile strength less than the handsheet tensile
strength of the non-naturally occurring hardwood pulp fiber in its
naturally occurring state as measured according to the Handsheet
Tensile Strength Test Method described herein.
[0046] In another example, the fibrous structure of the present
invention comprises one or more enzyme treated hardwood pulp fibers
that exhibit a handsheet tensile strength less than the handsheet
tensile strength of the non-enzyme treated hardwood pulp fiber as
measured according to the Handsheet Tensile Strength Test Method
described herein. In one example, the fibrous structure comprises
at least 5% and/or at least 10% and/or at least 20% and/or at least
30% and/or at least 40% to about 100% and/or to about 90% and/or to
about 80% and/or to about 70% and/or to about 60% by weight on a
dry fiber basis of enzyme treated hardwood pulp fibers that exhibit
a handsheet tensile strength less than the handsheet tensile
strength of the non-enzyme treated hardwood pulp fiber as measured
according to the Handsheet Tensile Strength Test Method described
herein.
[0047] In addition to the enzyme treated hardwood pulp fibers, the
fibrous structures of the present invention may comprise softwood
pulp fibers, such as Northern Softwood Kraft pulp fibers (NSK). In
one example, the fibrous structure comprises from about 0 to about
90% and/or from about 10 to about 80% and/or from about 30 to about
70% by weight on a dry fiber basis of softwood pulp fibers and from
about 10 to about 100% and/or from about 20 to about 90% and/or
from about 30 to about 70% by weight on a dry fiber basis of
hardwood pulp fibers at least a portion of which comprises enzyme
treated hardwood pulp fibers that exhibit a handsheet tensile
strength less than the handsheet tensile strength of the non-enzyme
treated hardwood pulp fiber as measured according to the Handsheet
Tensile Strength Test Method described herein.
Sanitary Tissue Product
[0048] The sanitary tissue products of the present invention may
exhibit a wet burst strength of greater than 420 g and/or greater
than 430 g and/or greater than 440 g and/or greater than 450 g
and/or greater than 460 g to about 2000 g and/or to about 1500 g
and/or to about 1000 g and/or to about 900 g and/or to about 800
g.
[0049] The sanitary tissue products of the present invention may
exhibit an initial total wet tensile of greater than 58 g/in and/or
greater than 60 g/in and/or greater than 62 g/in and/or greater
than 64 g/in and/or greater than 66 g/in to about 500 g/in and/or
to about 450 g/in and/or to about 400 g/in and/or to about 300 g/in
and/or to about 200 g/in and/or to about 100 g/in.
Method for Making Fibrous Structure
[0050] The fibrous structures of the present invention may be made
by any suitable method known in the art so long as one or more
non-naturally occurring hardwood pulp fibers that exhibit a
handsheet tensile strength less than the handsheet tensile strength
of the non-naturally occurring hardwood pulp fiber in its naturally
occurring state as measured according to the Handsheet Tensile
Strength Test Method described herein are used to make the fibrous
structure. In one example, a method for making a fibrous structure
according to the present invention comprises the steps of: [0051]
a. providing a fibrous composition comprising a non-naturally
occurring hardwood pulp fiber that exhibits a handsheet tensile
strength less than the handsheet tensile strength of the
non-naturally occurring hardwood pulp fiber in its naturally
occurring state as measured according to the Handsheet Tensile
Strength Test Method described herein; and [0052] b. depositing the
fibrous composition onto a collection device, such as a fabric
and/or a belt, to form a fibrous structure.
[0053] The method may further comprise one or more of the following
steps: creping, compressively dewatering, and through-air-drying
the fibrous structure.
[0054] The fibrous composition may comprise any suitable level of
non-naturally occurring hardwood pulp fibers, such as enzyme
treated hardwood pulp fibers.
Method for Making Sanitary Tissue Product
[0055] The sanitary tissue product of the present invention may be
made by any suitable method known in the art so long as one or more
fibrous structures of the present invention are used to make the
sanitary tissue product.
Test Methods
[0056] Unless otherwise indicated, all tests described herein
including those described under the Definitions section and the
following test methods are conducted on samples, fibrous structure
samples and/or sanitary tissue product samples and/or handsheets
that have been conditioned in a conditioned room at a temperature
of 73.degree. F..+-.4.degree. F. (about 23.degree.
C..+-.2.2.degree. C.) and a relative humidity of 50%.+-.10% for 2
hours prior to the test. Further, all tests are conducted in such
conditioned room. Tested samples and felts and any equipment or
materials should be subjected to 73.degree. F..+-.4.degree. F.
(about 23.degree. C..+-.2.2.degree. C.) and a relative humidity of
50%.+-.10% for 2 hours prior to testing.
Sample Preparation
[0057] To run the tests described below, handsheets must be
prepared. The handsheets are prepared as follows.
[0058] The handsheets are low density handsheets and are prepared
essentially according to TAPPI Standard T205 with the following
modifications which are believed to more accurately reflect the
sanitary tissue product manufacturing process.
[0059] For the handsheets, a fibrous slurry comprising tap water
(with no pH adjustment) and pulp fibers is used.
[0060] An embryonic web is formed by depositing the fibrous slurry
into a 12 inch.times.12 inch handsheet making apparatus on a
monofilament polyester wire supplied by Appleton Wire Co. of
Appleton Wis. The monofilament polyester wire has the following
specifications: dimensions of 13.5 inch.times.13.5 inch; machine
direction warp count of 84.+-.1.5 fibers/inch; cross direction warp
count of 76.+-.3 fibers/inch; warp size/type of 0.17 mm/9FU; shute
size/type of 0.17 mm/WP-110; caliper of 0.016.+-.0.0005 inch; and
air permeability of 720.+-.25 cubic feet/minute.
[0061] The embryonic web is then transferred by vacuum from the
monofilament polyester wire to a monofilament polyester papermaking
fabric supplied by Appleton Wire Co. of Appleton, Wis. and
dewatered by vacuum suction instead of pressing. The monofilament
polyester papermaking fabric has the following specifications:
dimensions 16 inch.times.14 inch; machine direction warp count of
36.+-.1 fibers/inch; cross direction warp count of 30.+-.3
fibers/inch; warp size/type of 0.40 mm/WP-87-12A-W; shute size/type
of 0.40 mm/WP-801-12A-W; caliper of 0.027.+-.0.001 inch; and air
permeability of 397.+-.25 cubic feet/minute.
[0062] The embryonic web and monofilament polyester wire are placed
on top of monofilament polyester papermaking fabric such that the
embryonic web contacts the papermaking fabric (a trilayer
configuration of wire/web/fabric with fabric side down) is formed.
The trilayer configuration is then passed lengthwise across a 13
inch.times. 1/16 inch wide vacuum slot box with a 90.degree. flare
set at a peak gauge reading of approximately 4.0 inches of Hg
vacuum. The rate of the trilayer configuration passing across the
vacuum slot should be uniform at a velocity of 16.+-.5
inches/second. The vacuum is then increased to achieve a peak gauge
reading of approximately 9.0 inches of Hg vacuum and the trilayer
configuration is passed lengthwise across the same vacuum slot at
the same rate of 16.+-.5 inches/second 2 more times to form a
handsheet. Note that the peak gauge reading is the amount of vacuum
measured as the trilayer configuration passes across the vacuum
slot.
[0063] The monofilament polyester wire is then carefully removed
from the handsheet ensuring that no pulp fibers stick to the wire.
The handsheet is then dried on a rotary drum dryer with a drying
felt by passing the handsheet and the papermaking fabric between
the drying felt and rotary drum dryer surface with the papermaking
fabric against the rotary drum dryer surface and again with a
second pass of the handsheet against the rotary drum dryer surface.
The rotary drum dryer surface specifications are as follows:
stainless steel polished finish cylinder with internal steam
heating, horizontally mounted; 17 inches in length and 13 inches in
diameter; 230.+-.5.degree. F.; rotation speed of 0.90.+-.0.05
revolutions/minute; dryer felt is endless, 80 inches circumference
by 16 inches wide, No. 11614, style X225, all wool from Noble Wood
Lab Machine Company, Hoosick Falls, N.Y.; dryer felt tension as low
and even as possible without slippage occurring between the dryer
felt and the rotary drum dryer surface and uniform tracking.
[0064] The dried handsheet is 12 inch.times.12 inch with a
resulting target basis weight of 16.5.+-.1 lb/3,000 ft.sup.2 and a
target density of 0.15.+-.0.06 g/cm.sup.3, unless otherwise
noted.
[0065] The dried handsheet is then conditioned as described above
before conducting any tests on the handsheets.
[0066] It will be recognized that the test methods described in
this section require the making of handsheets following the
specific procedure described above. Where a given product is in a
form that includes chemical additives or where the fibrous
structure is subjected to mechanical manipulation in generating the
product, it is to be recognized that the determination of whether
that product is within the scope of the present invention is made
by forming handsheets in accordance with the present description,
and measuring the physical properties of those handsheets, not
measuring the physical properties of the product itself. That is,
the fibers used to construct the product are used to make the
handsheets as described; no application of additives or mechanical
manipulation, aside from that discussed above, should occur.
[0067] From one handsheet, carefully cut four 1 in. wide strips of
sample 6.0.+-.0.1 inches in length in the "MD" direction. From a
second handsheet of the same sample set, carefully cut four 1 in.
wide strips of sample 6.0.+-.0.1 inches in length in the "CD"
direction. It is important that the cut be exactly perpendicular to
the long dimension of the strip. The strip should also be free of
wrinkles or excessive mechanical manipulation which can impact
flexibility. Mark the direction very lightly on one end, keeping
the same surface of the sample up for all strips. Later, the strips
will be turned over for testing, thus it is important that one
surface of the strip be clearly identified, however, it makes no
difference which surface of the sample is designated as the upper
surface.
Handsheet Tensile Strength Test Method
[0068] The Handsheet Tensile Strength Test is performed according
to TAPPI Standards T220 om-88 and T494 om-88 on 1 inch.times.6 inch
(about 2.5 cm.times.15.2 cm) strips of handsheets prepared as
described above. An electronic tensile tester (Intellect II-STD,
Thwing Albert Corp., Philadelphia, Pa.) is used and operated at a
crosshead speed of 4 inches/minute (about 10 cm/minute) and a
starting gauge length of 4 inches (about 10 cm). A minimum of n=8
tests are performed on each handsheet sample (4 machine direction
strips and 4 cross direction strips). The resulting tensile
strength values are recorded in g/in. and are divided by the
average basis weight of the handsheet sample. The handsheet tensile
strength for purpose of the present invention is the average of the
basis weight normalized tensile strength values.
PFR Test Method
[0069] PFR (pulp filtration resistance) is measured using the
following procedure. A sample of 2543 mL of a fiber suspension,
having 0.1% consistency, prepared in a 19 liters tank, through a
registry coupled to the bottom of a proportionate tank, returning
it to the tank through the top portion. Repeat the procedure (note
that the PFR must be carried out after taking 2543 mL for checking
the consistency since the height of the water column inside the
proportionate tank changes the measure value). Measure the
suspension temperature. Record the value in Celsius degrees.
Install the connection for PFR measuring in the inferior registry
of the proportionate tank of sample; Put the 100 mL glass flask
below the connection (note that since it refers to a dynamic
measurement having a specific recipient to this end, there is no
need to calibrate it). With a single and fast movement, open the
valve for sample collection and at the same time activate the
chronometer in order to measure the time, in seconds, required for
filling the 100 mL, flask up to its mark. Record the time "A", in
seconds. Discard the filtrate and without washing the screen of the
connection, measure the time needed for filling the flask again.
Record the time "B" in seconds. Repeat the previous item, recording
the time "C" in seconds. Remove the connection and wash it in
counter flow so as to remove all the pulp retained, checking that
the connection sieve is clean and free of fibers which may dry and
change further tests. Calculate the PFR value as follows:
PFR= {square root over (E.times.(B+C-2A)/1,5)}
wherein: [0070] A, B and C=time measurements in seconds. [0071]
E=1+0.013 (T-75) [0072] T=temperature in Fahrenheit degrees. A
short formula may be used:
[0072] PFR=Kx {square root over (B+C-2A)}
wherein:
K= {square root over (E/1,5)}
then:
K= {square root over ([1+0,013(T-75)])}
[0073] "K" values to temperatures ranging from 70.degree. F.
(21.degree. C.) and 77.degree. F. (25.degree. C.).
TABLE-US-00002 .degree. C. .degree. F. "K" factor 21.0 69.8 0.7884
21.5 70.7 0.7933 22.0 71.6 0.7982 22.5 72.5 0.8031 23.0 73.4 0.8080
23.5 74.3 0.8128 24.0 75.2 0.8176 24.5 76.1 0.8223 25.0 77.0
0.8270
[0074] The pulp filtration resistance (PFR) can be obtained by
measuring the Canadian Standard Freeness (CSF) according to TAPPI
Standard T-227 om-09. CSF is related to PFR by the following
equation: PFR=78918*CSF.sup.-1.4688.
Wet Burst Strength Test Method
[0075] Wet burst strength may be measured using a Thwing-Albert
Burst Tester Cat. No. 177 equipped with a 2000 g load cell
commercially available from Thwing-Albert Instrument Company,
Philadelphia, Pa.
[0076] Wet burst strength is measured by taking two sanitary tissue
product samples. Using scissors, cut the samples in half in the MD
so that they are approximately 228 mm in the machine direction and
approximately 114 mm in the cross machine direction, each two (2)
plies thick (you now have 4 samples). First, condition the samples
for two (2) hours at a temperature of 73.degree. F..+-.2.degree. F.
(about 23.degree. C..+-.1.degree. C.) and a relative humidity of
50%.+-.2%. Next age the samples by stacking the samples together
with a small paper clip and "fan" the other end of the stack of
samples by a clamp in a 105.degree. C. (.+-.1.degree. C.) forced
draft oven for 5 minutes (.+-.10 seconds). After the heating
period, remove the sample stack from the oven and cool for a
minimum of three (3) minutes before testing. Take one sample strip,
holding the sample by the narrow cross machine direction edges,
dipping the center of the sample into a pan filled with about 25 mm
of distilled water. Leave the sample in the water four (4)
(.+-.0.5) seconds. Remove and drain for three (3) (.+-.0.5) seconds
holding the sample so the water runs off in the cross machine
direction. Proceed with the test immediately after the drain step.
Place the wet sample on the lower ring of a sample holding device
of the Burst Tester with the outer surface of the sample facing up
so that the wet part of the sample completely covers the open
surface of the sample holding ring. If wrinkles are present,
discard the samples and repeat with a new sample. After the sample
is properly in place on the lower sample holding ring, turn the
switch that lowers the upper ring on the Burst Tester. The sample
to be tested is now securely gripped in the sample holding unit.
Start the burst test immediately at this point by pressing the
start button on the Burst Tester. A plunger will begin to rise
toward the wet surface of the sample. At the point when the sample
tears or ruptures, report the maximum reading. The plunger will
automatically reverse and return to its original starting position.
Repeat this procedure on three (3) more samples for a total of four
(4) tests, i.e., four (4) replicates. Report the results as an
average of the four (4) replicates, to the nearest g.
Initial Total Wet Tensile Test Method
[0077] The initial total wet tensile of sanitary tissue products of
the present invention is determined using a Thwing-Albert EJA
Material Tester Instrument, Cat. No. 1350, equipped with 5000 g
load cell available from Thwing-Albert Instrument Company, 14
Collings Ave. W. Berlin, N.J. 08091.10% of the 5000 g load cell is
utilized for the wet tensile test.
[0078] i. Sample Preparation--A strip of sample to be tested [2.54
cm (1 inch) wide by greater than 5.08 cm (2 inches)] long is
obtained.
[0079] ii. Operation--The test settings for the instrument are:
Crosshead speed--10.16 cm/minute (4.0 in/minute) Initial gauge
length--2.54 cm (1.0 inch)
[0080] Adjust the load cell to read zero plus or minus 0.5
grams.sub.force.
[0081] iii. Testing Samples--One end of the sample strip is placed
between the upper jaws of the machine and clamped. After verifying
that the sample strip is hanging straight between the lower jaws,
clamp the other end of the sample strip in the lower jaws.
[0082] a. Pre-Test--Strain the sample strip to 25 grams.sub.force
(+/-10 grams.sub.force) at a strain rate of 3.38 cm/minute (1.33
in/minute) prior to wetting the sample strip. The distance between
the upper and lower jaws now being greater than 2.54 cm (1.0 inch).
This distance now becomes the new zero-strain position for the
forthcoming wet test.
[0083] b. Wet Test--While the sample strip is still at 25
grams.sub.force (+/-10 grams.sub.force), it is wetted, starting
near the upper jaws, a water/0.1% Pegosperse.RTM. ML200 (available
from Lonza Inc. of Allendale, N.J.) solution [having a temperature
of about 73.degree. F..+-.4.degree. F. (about 23.degree.
C..+-.2.2.degree. C.)] is delivered to the sample strip via a 2 ml
disposable pipet. Do not contact the sample strip with the pipet
and do not damage the sample strip by using excessive squirting
pressure. The solution is continuously added until the sample strip
is visually determined to be completely saturated between the upper
and lower jaws. At this point, the load cell is re-adjusted to read
zero plus or minus 0.5 grams.sub.force.
[0084] The sample strip is then strained at a rate of 10.16
cm/minute (4 inches/minute) and continues until the sample strip is
strained past its failure point (failure point being defined as the
point on the force-strain curve where the sample strip falls to 50%
of its peak strength after it has been strained past its peak
strength). The straining of the sample strip is initiated between
5-10 seconds after the sample is initially wetted. The initial
result of the test is an array of data points in the form of load
(grams.sub.force) versus strain (where strain is calculated as the
crosshead displacement (cm of jaw movement from starting point)
divided by the initial separation distance (cm) between the upper
and lower jaws after the pre-test.
[0085] The sample is tested in two orientations, referred to here
as MD (machine direction, i.e., in the same direction as the
continuously wound reel and forming fabric) and CD (cross-machine
direction, i.e., 90.degree. from MD). The MD and CD wet tensile
strengths are determined using the above equipment and calculations
in the following manner:
ITWT(g.sub.f/inch)=Peak Load.sub.MD(g.sub.f)/1(inch.sub.width)+Peak
Load.sub.CD(g.sub.f)/1(inch.sub.width)
Non-limiting Examples
Example 1
Multi-ply Sanitary Tissue Product Using Non-Enzyme Treated Hardwood
Pulp Fibers (Control)
[0086] A pilot scale Fourdrinier papermaking machine is used in the
present example. A 3% by weight aqueous slurry of Northern Softwood
Kraft (NSK) (50/50 mixture of softwood pulp marketed by Abitibi
Bowater Incorporated of Montreal, PQ, Canada and by Zellstof
Celgar, Mercer International from Castlegar, BC, Canada mill) is
made up in a conventional re-pulper. The NSK slurry is refined
gently and a 3% solution of a permanent wet strength resin (i.e.
Kymene 1142 marketed by Hercules Incorporated of Wilmington, Del.)
is added to the NSK stock pipe at a rate of 1% by weight of the dry
fibers. The adsorption of Kymene 1142 to NSK is enhanced by an
in-line mixer. A 1% solution of Carboxy Methyl Cellulose (CMC)
(i.e. FinnFix from CP Kelco U.S., Inc. of Atlanta, Ga.) is added
after the in-line mixer at a rate of 0.35% by weight of the dry
fibers to enhance the dry strength of the fibrous substrate. A 3%
by weight aqueous slurry Eucalyptus fibers (from Fibria's Aracruz,
Brazil mill) is made up in a conventional re-pulper. A 1% solution
of defoamer (i.e. Advantage DF285 marketed by Hercules Incorporated
of Wilmington, Del.) is added to eucalyptus line before the in-line
mixer at a rate of 0.05% by weight of the dry fibers.
[0087] The NSK furnish and the Eucalyptus fibers are fed to the
head box and deposited onto a Fourdrinier wire as a homogenous
mixture to form an embryonic web. Dewatering occurs through the
Foudrinier wire and is assisted by a deflector and vacuum boxes.
The Fourdrinier wire is of a 5-shed, satin weave configuration
having 84 machine-direction and 76 cross-machine-direction
monofilaments per inch, respectively. The embryonic wet web is
transferred from the Fourdrinier wire, at a fiber consistency of
about 19% at the point of transfer, to a photo-polymer fabric
having 150 SP cells per square inch, 25 percent knuckle areas and
18.5 mils of photo-polymer depth. Further de-watering is
accomplished by vacuum assisted drainage until the web has a fiber
consistency of about 23%. The patterned web is pre-dried by air
blow-through to a fiber consistency of about 60% by weight. The web
is then adhered to the surface of a Yankee dryer with a sprayed
creping adhesive comprising aqueous solution of Polyvinyl Alcohol
(PVA) (i.e. Vinylon 88-44 marketed by Wego Chemical and mineral
corporation of Great Neck, N.Y.) at a rate of 0.1% by weight and a
crepe aid (i.e. Unicrepe 457T20 marketed by Georgia Pacific
Chemicals LLC of Atlanta, Ga.) at a rate of 0.025% by weight of the
dry fibers. The fiber consistency is increased to an estimated 96%
before the dry creping the web with a doctor blade. The doctor
blade has a bevel angle of about 25 degrees and is positioned with
respect to the Yankee dryer to provide an impact angle of about 81
degrees; the Yankee dryer is operated at about 800 fpm (feet per
minute) (about 244 meters per minute). The dry web is formed into
roll at a speed of 760 fpm (232 meters per minutes).
[0088] Two plies of the web are formed into a 2-ply paper towel by
embossing and laminating them together using PVA adhesive. The
2-ply paper towel has about 47 g/m.sup.2 basis weight and contains
65% by weight Northern Softwood Kraft and 35% by weight Eucalyptus
furnish. The 2-ply towel exhibits a wet burst strength of about 418
g, total dry tensile of about 2297 g/in and wet burst strength to
total dry tensile ratio of 0.18.
Example 2
Multi-ply Sanitary Tissue Product Using Enzyme Treated Hardwood
Pulp Fibers (Invention)
[0089] A paper towel is made by a method similar to that of Example
1, but replacing the Eucalyptus fibers with enzyme treated
Eucalyptus pulp fibers from Fibria, Brazil. The Eucalyptus pulp
fibers are treated by Fibria as follows. A xylanase enzymatic
treatment stage is carried out using a xylanase charge of 1
kilogram of xylanase/ton of cellulose, pH of about 7, temperature
of 75.degree. C., in a 3 hour treatment, using a suspension at 11%
consistency. An acid step is then performed at 90.degree. C., pH of
about 3 to 4.5 using sulfuric or hydrochloric acid to set the pH,
for 3 hours and 11% consistency.
[0090] After the enzymatic treatment, a method to denature the
enzyme was conducted, which consisted of washing the treated
cellulose, dewatering until a consistency of 25 to 30% by weight is
achieved, and heating of the medium to 85 to 95.degree. C. for 10
to 15 minutes.
[0091] The xylanase can be obtained from Novozymes A/S of Bagsvxrd,
Denmark. The xylanase is used at a rate of 0.1% by weight of dry
pulp fibers during the bleaching sequence having an acid step.
[0092] The 2-ply paper towel made has about 47 g/m.sup.2 basis
weight and contains 65% by weight Northern Softwood Kraft and 35%
by weight xylanase treated Eucalyptus. The 2-ply towel exhibits a
wet burst strength of about 465 g, total dry tensile of about 2337
g/in and wet burst strength to total dry tensile ratio of 0.20.
Example 3
Multi-ply Sanitary Tissue Product Using Enzyme Treated Hardwood
Pulp Fibers (Invention)
[0093] A paper towel is made by a method similar to that of Example
1, but replacing the Eucalyptus fiber with enzyme treated
Eucalyptus pulp fibers from Fibria, Brazil. The Eucalyptus pulp
fibers are treated by Fibria as follows. A first enzymatic
treatment stage is carried out using a xylanase charge of 0.5
kilogram of xylanase/ton of cellulose, pH of about 7, temperature
of 75.degree. C., in a 3 hour treatment, using a suspension at 11%
consistency. A second enzyme treatment stage is performed using a
cellulase charge of 1 kilogram of cellulase/ton of cellulose, pH of
about 7. The acid step is performed at 90.degree. C., pH of about 3
to 4.5 using sulfuric or hydrochloric acid to set the pH, for 3
hours and 11% consistency.
[0094] After the enzymatic treatment, a method to denature the
enzyme was conducted, which consisted of washing the treated
cellulose, dewatering until a consistency of 25 to 30% by weight is
achieved, and heating of the medium to 85 to 95.degree. C. for 10
to 15 minutes.
[0095] The xylanase and cellulase can be obtained from Novozymes
A/S of Bagsvxrd, Denmark. The xylanase is used at a rate of 0.05%
by weight of dry pulp fibers and the cellulase is used at a rate of
0.1% by weight of dry pulp fibers during the bleaching sequence
having an acid step.
[0096] The 2-ply paper towel has about 47 g/m.sup.2 basis weight
and contains 65% by weight Northern Softwood Kraft and 35% by
weight xylanase and cellulase treated Eucalyptus. The 2-ply towel
exhibits a wet burst strength of about 464 g, total dry tensile of
about 2331 g/in and wet burst strength to total dry tensile ratio
of 0.20.
Example 4
Multi-ply Sanitary Tissue Product Using Non-Enzyme Treated Hardwood
Pulp Fibers (Control)
[0097] A pilot scale Fourdrinier papermaking machine is used in the
present example. A 3% by weight aqueous slurry of Northern Softwood
Kraft (NSK) (marketed by Weyerhaeuser Co. Federal Way, Wash.) is
made up in a conventional re-pulper. The NSK slurry is passed
through a refiner at no load and a 1% solution of a aldehyde
functionalized cationic polyacrylamide temporary wet strength resin
(i.e. PAREZ 750C marketed by Kemira Chemicals, Inc. of Kennesaw,
Ga.) is added to the NSK stock pipe at a rate of 0.125% by weight
of the dry fibers. A 3% by weight aqueous slurry Eucalyptus fibers
(from Fibria's Aracruz, Brazil mill) is made up in a conventional
re-pulper. A 1% solution of a aldehyde functionalized cationic
polyacrylamide temporary wet strength resin (i.e. PAREZ 750C
marketed by Kemira Chemicals, Inc. of Kennesaw, Ga.) is added to
the Eucalyptus stock pipe at a rate of 0.025% by weight of the dry
fibers.
[0098] The NSK furnish and the Eucalyptus fibers are layered in the
head box and deposited onto a Fourdrinier wire as different layers
to form an embryonic web. Dewatering occurs through the Foudrinier
wire and is assisted by a deflector and vacuum boxes. The
Fourdrinier wire is of a 5-shed, satin weave configuration having
84 machine-direction and 76 cross-machine-direction monofilaments
per inch, respectively. The embryonic wet web is transferred from
the Fourdrinier wire, at a fiber consistency of about 19% at the
point of transfer, to a photo-polymer fabric having 20 Structured
Linearly Aligned Molding cells per square inch, 40 percent knuckle
areas and 11.6 mils of photo-polymer depth. Further de-watering is
accomplished by vacuum assisted drainage until the web has a fiber
consistency of about 26%. The patterned web is pre-dried by air
blow-through to a fiber consistency of about 54% by weight. The web
is then adhered to the surface of a Yankee dryer with a sprayed
creping adhesive comprising aqueous solution of Polyvinyl Alcohol
(PVA) (i.e. Vinylon 88-44 marketed by Wego Chemical and mineral
corporation of Great Neck, N.Y.) at a rate of 0.1% by weight and a
crepe aid (i.e. Unicrepe 457T20 marketed by Georgia Pacific
Chemicals LLC of Atlanta, Ga.) at a rate of 0.025% by weight of the
dry fibers. The fiber consistency is increased to an estimated 96%
before the dry creping the web with a doctor blade. The doctor
blade has a bevel angle of about 25 degrees and is positioned with
respect to the Yankee dryer to provide an impact angle of about 81
degrees; the Yankee dryer is operated at about 800 fpm (feet per
minute) (about 244 meters per minute). The dry web is formed into
roll at a speed of 672 fpm (205 meters per minutes).
[0099] Two plies of the web are formed into toilet paper products
by laminating them together using a hot melt adhesive (i.e.
Cycloflex 34-121C marketed by Henkel Corporation of Bridgewater,
N.J.). A cationic quad based surfactant at a rate of 0.375% by
weight of the dry fibers also applied to the product. The 2-ply
toilet paper has about 50.4 g/m.sup.2 basis weight and contains 35%
by weight Northern Softwood Kraft and 65% by weight Eucalyptus
furnish. The 2-ply toilet paper exhibits an initial total wet
tensile of about 56.6 g/in, total dry tensile of about 475.6 g/in
and initial total wet tensile to total dry tensile ratio of
0.119.
Example 5
Multi-ply Sanitary Tissue Product Using Enzyme Treated Hardwood
Pulp Fibers (Invention)
[0100] A toilet paper is made by a method similar to that of
Example 4, but replacing the Eucalyptus fiber with enzyme treated
Eucalyptus pulp fibers from Fibria, Brazil. The Eucalyptus pulp
fibers are treated by Fibria as follows. A xylanase enzymatic
treatment stage is carried out using a xylanase charge of 1
kilogram of xylanase/ton of cellulose, pH of about 7, temperature
of 75.degree. C., in a 3 hour treatment, using a suspension at 11%
consistency. An acid step is then performed at 90.degree. C., pH of
about 3 to 4.5 using sulfuric or hydrochloric acid to set the pH,
for 3 hours and 11% consistency.
[0101] After the enzymatic treatment, a method to denature the
enzyme was conducted, which consisted of washing the treated
cellulose, dewatering until a consistency of 25 to 30% by weight is
achieved, and heating of the medium to 85 to 95.degree. C. for 10
to 15 minutes.
[0102] The xylanase can be obtained from Novozymes A/S of Bagsvard,
Denmark. The xylanase is used at a rate of 0.1% by weight of dry
pulp fibers during the bleaching sequence having an acid step.
[0103] The 2-ply toilet paper has about 50.4 g/m.sup.2 basis weight
and contains 35% by weight Northern Softwood Kraft and 65% by
weight xylanase treated Eucalyptus. The 2-ply toilet paper exhibits
an initial total wet tensile of about 62.6 g/in, total dry tensile
of about 475.4 m/in and initial total wet tensile to total dry
tensile ratio of 0.132.
Example 6
Multi-ply Sanitary Tissue Product Using Enzyme Treated Hardwood
Pulp Fibers (Invention)
[0104] A toilet paper is made by a method similar to that of
Example 4, but replacing the Eucalyptus fiber with enzyme treated
Eucalyptus pulp fibers from Fibria, Brazil. The Eucalyptus pulp
fibers are treated by Fibria as follows. A first enzymatic
treatment stage is carried out using a xylanase charge of 0.5
kilogram of xylanase/ton of cellulose, pH of about 7, temperature
of 75.degree. C., in a 3 hour treatment, using a suspension at 11%
consistency. A second enzyme treatment stage is performed using a
cellulase charge of 1 kilogram of cellulase/ton of cellulose, pH of
about 7. The acid step is performed at 90.degree. C., pH of about 3
to 4.5 using sulfuric or hydrochloric acid to set the pH, for 3
hours and 11% consistency.
[0105] After the enzymatic treatment, a method to denature the
enzyme was conducted, which consisted of washing the treated
cellulose, dewatering until a consistency of 25 to 30% by weight is
achieved, and heating of the medium to 85 to 95.degree. C. for 10
to 15 minutes.
[0106] The xylanase and cellulase can be obtained from Novozymes
A/S of Bagsvxrd, Denmark. The xylanase is used at a rate of 0.05%
by weight of dry pulp fibers and the cellulase is used at a rate of
0.1% by weight of dry pulp fibers during the bleaching sequence
having an acid step.
[0107] The 2-ply toilet paper has about 50.4 g/m.sup.2 basis weight
and contains 35% by weight Northern Softwood Kraft and 65% by
weight xylanase and cellulase treated Eucalyptus. The 2-ply toilet
paper exhibits an initial total wet tensile of about 65.8 g/in,
total dry tensile of about 519.6 g/in and initial total wet tensile
to total dry tensile ratio of 0.127.
Example 7
Multi-ply Sanitary Tissue Product Using Enzyme Treated Hardwood
Pulp Fibers (Invention)
[0108] A toilet paper is made by a method similar to that of
Example 4, but replacing the Eucalyptus fiber with enzyme treated
Eucalyptus pulp fibers from Fibria, Brazil. The Eucalyptus pulp
fibers are treated by Fibria as follows. A xylanase enzymatic
treatment stage is carried out using a xylanase charge of 0.5
kilogram of xylanase/ton of cellulose, pH of about 7, temperature
of 75.degree. C., in a 3 hour treatment, using a suspension at 11%
consistency. An acid step is then performed at 90.degree. C., pH of
about 3 to 4.5 using sulfuric or hydrochloric acid to set the pH,
for 3 hours and 11% consistency.
[0109] After the enzymatic treatment, a method to denature the
enzyme was conducted, which consisted of washing the treated
cellulose, dewatering until a consistency of 25 to 30% by weight is
achieved, and heating of the medium to 85 to 95.degree. C. for 10
to 15 minutes.
[0110] The xylanase can be obtained from Verenium Corporation of
San Diego, Calif. The xylanase is used at a rate of 0.05% by weight
of dry pulp fibers during the bleaching sequence having an acid
step.
[0111] The 2-ply toilet paper has about 50.4 g/m.sup.2 basis weight
and contains 35% by weight Northern Softwood Kraft and 65% by
weight xylanase treated Eucalyptus. The 2-ply toilet paper exhibits
an initial total wet tensile of about 68.4 g/in, total dry tensile
of about 505 g/in and initial total wet tensile to total dry
tensile ratio of 0.135.
[0112] The dimensions and values disclosed herein are not to be
understood as being strictly limited to the exact numerical values
recited. Instead, unless otherwise specified, each such dimension
is intended to mean both the recited value and a functionally
equivalent range surrounding that value. For example, a dimension
disclosed as "40 mm" is intended to mean "about 40 mm."
[0113] Every document cited herein, including any cross referenced
or related patent or application, is hereby incorporated herein by
reference in its entirety unless expressly excluded or otherwise
limited. The citation of any document is not an admission that it
is prior art with respect to any invention disclosed or claimed
herein or that it alone, or in any combination with any other
reference or references, teaches, suggests or discloses any such
invention. Further, to the extent that any meaning or definition of
a term in this document conflicts with any meaning or definition of
the same term in a document incorporated by reference, the meaning
or definition assigned to that term in this document shall
govern.
[0114] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
* * * * *