U.S. patent application number 10/390533 was filed with the patent office on 2005-01-06 for saccharide treated cellulose pulp sheets.
Invention is credited to West, Hugh.
Application Number | 20050000669 10/390533 |
Document ID | / |
Family ID | 32771659 |
Filed Date | 2005-01-06 |
United States Patent
Application |
20050000669 |
Kind Code |
A1 |
West, Hugh |
January 6, 2005 |
Saccharide treated cellulose pulp sheets
Abstract
Cellulose pulp sheets treated with a saccharide yield less than
20 wt. % knots when fiberized under standard Kamas conditions. The
fiberized sheets when airlaid produce fiber webs that exhibit
desirable densification properties and softness properties.
Inventors: |
West, Hugh; (Seattle,
WA) |
Correspondence
Address: |
WEYERHAEUSER COMPANY
INTELLECTUAL PROPERTY DEPT., CH 1J27
P.O. BOX 9777
FEDERAL WAY
WA
98063
US
|
Family ID: |
32771659 |
Appl. No.: |
10/390533 |
Filed: |
March 14, 2003 |
Current U.S.
Class: |
162/175 ;
162/158 |
Current CPC
Class: |
A61F 13/53 20130101;
A61L 15/28 20130101; A61L 15/28 20130101; D21C 9/005 20130101; A61L
15/20 20130101; A61F 2013/530007 20130101; C08L 1/02 20130101 |
Class at
Publication: |
162/175 ;
162/158 |
International
Class: |
D21H 017/20 |
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A cellulose pulp sheet comprising: cellulose fibers; and a
saccharide, wherein the pulp sheet when fiberized under standard
Kamas conditions yields less than 20 wt. % knots.
2. The cellulose pulp sheet of claim 1 having a density greater
than about 0.3 g/cm.sup.3.
3. The cellulose pulp sheet of claim 1, wherein the cellulose
fibers are wood pulp fibers.
4. The cellulose pulp sheet of claim 1, wherein the saccharide is a
corn syrup.
5. The cellulose pulp sheet of claim 4, wherein the corn syrup is
applied at a solids content less than about 65 wt. %.
6. The cellulose pulp sheet of claim 4, wherein the corn syrup
includes solids that are present in an amount less than 10 wt. %
based on the weight of dry cellulose fiber in the cellulose pulp
sheet.
7. The cellulose pulp sheet of claim 1, wherein the saccharide is a
high fructose corn syrup.
8. The cellulose pulp sheet of claim 7, wherein the high fructose
corn syrup is applied at a solids content less than about 65 wt.
%.
9. The cellulose pulp sheet of claim 7, wherein the high fructose
corn syrup includes high fructose corn syrup solids that are
present in an amount less than about 10 wt. % based on the weight
of dry cellulose fiber in the cellulose pulp sheet.
10. A cellulose pulp sheet consisting essentially of: cellulose
fibers; a corn syrup, wherein the pulp sheet when fiberized under
standard Kamas conditions yields less than 20 wt. % knots.
11. The cellulose pulp sheet of claim 10 wherein the corn syrup is
high fructose corn syrup.
12. A method for producing a saccharide treated cellulose pulp
sheet that when fiberized under standard Kamas conditions yields
less than 20 wt. % knots comprising: providing a cellulose pulp
sheet; and applying a saccharide to the cellulose pulp sheet.
13. The method of claim 12, wherein the cellulose pulp sheet has a
density greater than about 0.3 g/cm.sup.3.
14. The method of claim 12, wherein the cellulose pulp sheet
comprises wood pulp fibers.
15. The method of claim 12, wherein the saccharide is a corn
syrup.
16. The method of claim 15, wherein the corn syrup has a solids
content less than about 65 wt. %.
17. The method of claim 15, wherein the corn syrup is applied to
the cellulose pulp sheet so that the corn syrup solids content of
the saccharide treated cellulose pulp sheet is less than 10 wt. %
based on the dry weight of the cellulose fiber in the saccharide
treated cellulose pulp sheet.
18. The method of claim 12, wherein the saccharide is a high
fructose corn syrup.
19. The method of claim 18, wherein the high fructose corn syrup
has a solids content less than about 65 wt. %.
20. The method of claim 18, wherein the high fructose corn syrup is
applied to the cellulose pulp sheet so that the high fructose corn
syrup solids content of the saccharide treated cellulose pulp sheet
is less than 10 wt. % based on the dry weight of the cellulose
fibers in the saccharide treated cellulose pulp sheet.
21. A cellulose pulp in non-sheet form comprising: a mass of
cellulose fibers, the mass having a density of at least 0.3
g/cm.sup.3; and a saccharide, wherein the cellulose pulp in
non-sheet form, when fiberized under standard Kamas conditions
yields less than 20 wt. % knots.
22. An absorbent product comprising a fiberized cellulose pulp
sheet of claim 1 or 10.
23. An absorbent product comprising a fiberized cellulose pulp of
claim 21.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to cellulose fibers that have
been treated with a saccharide in order to modify the properties of
the cellulose fibers and to methods for applying saccharides to
cellulose fibers.
BACKGROUND OF THE INVENTION
[0002] Cellulose fibers have found widespread application in
absorbent articles, such as diapers and feminine hygiene products.
The cellulose fibers are generally used as an absorbent medium to
acquire, transport, and hold fluids. While cellulose fibers are
effective at acquiring, transporting, and holding fluids, many
improvements to cellulose fibers have been made over the past
decades to improve the performance properties of cellulose fibers
in absorbent products. For example, U.S. Pat. Nos. 6,340,411 and
5,547,541 describe that webs of cellulose fibers treated with
certain polymeric and nonpolymeric materials require less pressure
to densify the web to a given density as compared to the pressure
needed to densify a similar web without the polymeric or
nonpolymeric material present.
[0003] The cellulose fibers treated with the compositions described
in U.S. Pat. No. 5,547,541 are manufactured by applying the desired
compositions to a wet laid web of cellulose fibers which has been
produced, for example, using a Fourdrinier machine. The treated wet
laid web of cellulose fibers is generally formed into a roll for
bulk delivery to an absorbent product manufacturer. The absorbent
product manufacturer typically unrolls the roll and processes the
web in a fiberization unit that individualizes the fibers and
prepares them for further processing.
[0004] Several challenges are faced by absorbent product
manufacturers when producing products from the treated cellulose
fibers discussed above. The ability of the fibers to be
individualized affects both the visual appearance of the final
product and the ability of the resulting fluff to perform its
function of separating and distributing the superabsorbent
particles which are typically admixed with it. Knots are defined as
clumps or bunches of fibers that have not been individualized. It
is well known that the utility and acceptability of a mat of fibers
decreases with an increasing level of knot content.
[0005] The absorbent product industry is a competitive industry
where there is constant downward pressure on the cost of raw
materials. The search for desirable treatment chemicals is limited
by the need of the industry to use chemicals which are safe and
which are not susceptible to a negative perception by the consuming
public.
[0006] U.S. Pat. No. 3,903,889 describes a process for adhering
absorbent particles to fibers, an airlaid web of crepe paper, or
tissue paper using corn syrup solids, honey, and dextrins which can
be diluted with organic solvents. U.S. Pat. No. 5,789,326 which
discusses U.S. Pat. No. 3,903,889 notes that corn syrup is not a
hygroscopic material and that corn syrup is excluded as an
acceptable binder for attaching superabsorbent particles to fibers
in some embodiments because corn syrup remains tacky upon drying.
U.S. Pat. No. 5,789,326 also describes that such tacky binders make
processing of binder coated fibers difficult, e.g., the application
of neat corn syrup to cellulose fibers makes the fibers more
difficult to fiberize. Poorly fiberized cellulose fibers airlaid
into webs are less desirable compared to airlaid webs of fibers
that are fiberized to a greater extent. Heretofore, corn syrup has
not found use in the manufacture of customized cellulose fibers
which have been treated to modify their properties, despite the
favorable economics of using corn syrup. Manufacturers of absorbent
products continue to look for effective and economical alternatives
to existing cellulose fibers for use in their products.
SUMMARY OF THE INVENTION
[0007] Surprisingly, the present inventors have observed that
cellulose pulp sheets treated with a saccharide in accordance with
the present invention are readily fiberizable within the
requirements of absorbent product manufacturers. Fibers resulting
from the fiberization of cellulose pulp sheets treated with
saccharides in accordance with the present invention exhibit
densification and softness properties that are superior to
densification and softness properties of fibers resulting from
cellulose pulp sheets that have not been treated in accordance with
the present invention. Absorbent product manufacturers will find
saccharide treated cellulose pulp sheets desirable because of their
fiberization properties and the densification and softness
properties of the fibers produced from the treated pulp sheets. In
addition, absorbent product manufacturers will consider saccharides
desirable because of their low cost and perceived safety by the
consuming public and the absence of any negative perception.
[0008] In one embodiment, the present invention relates to a
cellulose pulp sheet that includes cellulose fibers, and a
saccharide, wherein the pulp sheet when fiberized under standard
Kamas conditions yields less than 20 wt. % knots.
[0009] In another embodiment, the present invention relates to a
method of producing a cellulose pulp sheet that when fiberized
under standard Kamas conditions yields less than 20 wt. % knots.
The method includes providing a cellulose pulp sheet and applying a
saccharide to the cellulose pulp sheet.
[0010] In a preferred embodiment, the cellulose pulp sheet consists
essentially of cellulose fibers, a saccharide, and water introduced
with the saccharide as it is applied to the cellulose pulp
sheet.
[0011] In another embodiment, the present invention is a cellulose
pulp in non-sheet form that includes a mass of cellulose fibers,
wherein the mass has a density of at least 0.3 g/cm.sup.3; and a
saccharide, wherein the cellulose pulp in non-sheet form when
fiberized under standard Kamas conditions yields less than 20 wt. %
knots.
[0012] The present invention provides absorbent product
manufacturers with a source of cellulose pulp sheets that exhibit
desirable fiberization properties resulting in fibers that exhibit
desirable densification and softness properties.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The foregoing aspects and many of the attendant advantages
of this invention will become more readily appreciated as the same
become better understood by reference to the following detailed
description, when taken in conjunction with the accompanying
drawings, wherein:
[0014] FIG. 1 is a graph illustrating the difference in
densification properties between fibers resulting from the
fiberization of high fructose corn syrup treated cellulose pulp
sheets of the present invention and fibers resulting from the
fiberization of cellulose pulp sheets which have not been treated
in accordance with the present invention;
[0015] FIG. 2 is a graph illustrating the softness properties of
fibers resulting from the fiberization of high fructose corn syrup
treated cellulose pulp sheets of the present invention compared to
the softness properties of fibers resulting from the fiberization
of cellulose pulp sheets that have not been treated in accordance
with the present invention;
[0016] FIG. 3 is a schematic illustration of a sonic fractionator
used to determine the knot level of fiberized cellulose fibers;
[0017] FIG. 4 is a schematic illustration of a wet laid web
manufacturing line illustrating the application of a saccharide to
a wet laid web of cellulose fibers in accordance with the present
invention; and
[0018] FIG. 5 is a graph illustrating the difference in
densification properties between fibers resulting from the
fiberization of honey, sucrose and maltodextrine treated cellulose
pulp sheets of the present invention and fibers resulting from the
fiberization of cellulose pulp sheets that have not been treated in
accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0019] As used herein, the term saccharide refers to mono-, di-,
oligo-, and polysaccharides.
[0020] Monosaccharides are carbohydrates that cannot be hydrolyzed
into smaller, simpler carbohydrates. Examples of monosaccharides
include glucose, fructose, glyceraldehyde, dihydroxyacetone,
erythrose, threose, ribose, deoxyribose, galactose, and the
like.
[0021] Disaccharides are carbohydrates that on a molar basis
undergo hydrolysis to produce only two moles of a monosaccharide.
Examples of disaccharides include maltose, sucrose, cellubiose,
lactose, and the like.
[0022] Oligosaccharides are carbohydrates that on a molar basis
undergo hydrolysis to produce 3 to 10 moles of a monosaccharide.
Examples of oligosaccharides include those found in corn syrups and
other mixtures of breakdown products from polysaccharides, and the
like.
[0023] Polysaccharides are carbohydrates that on a molar basis
undergo hydrolysis to produce more than ten moles of a
monosaccharide. Examples of polysaccharides include starch, chitin,
hemicelluloses such as galactomannan, other polysaccharides found
in seaweed, and the like.
[0024] It should be understood that the term saccharide as used
herein not only refers to individual saccharides such as glucose,
fructose, or lactose, but also includes mixtures of
monosaccharides, disaccharides, oligosaccharides, and/or
polysaccharides.
[0025] Examples of saccharides that include a mixture of
monosaccharides, disaccharides, oligosaccharides, or
polysaccharides include corn syrup, high fructose corn syrup, and
honey. Corn syrup is generally a mixture of dextrose (glucose),
maltose, and maltodextrines and is available from numerous
commercial sources. High fructose corn syrup generally includes
fructose, dextrose, disaccharides, and other saccharides. Corn
syrup and high fructose corn syrup typically are available as
aqueous solutions and have a solids content that ranges from 70 to
85 wt. %. An exemplary high fructose corn syrup is available from
Archer-Daniels Midland Company under the trademark Corn Sweet.RTM.
42. It should be understood that other high fructose corn syrups
that are available from Archer-Daniels Midland Company and other
commercial sources are useful in the present invention.
[0026] Honey useful in accordance with the present invention
contains fructose and glucose as the predominate carbohydrates,
with maltos and sucrose present in small percentages. Honey is
available from numerous commercial sources.
[0027] Exemplary cellulose pulp sheets useful in the present
invention are derived from plant sources such as cotton, flax,
bagasse, hemp, jute, rice, wheat, bamboo, corn, sisal, kenaf, peat
moss, and the like. Preferred cellulose pulp sheets are wood pulp
sheets such as those described in U.S. Pat. No. 5,789,326.
Generally, such wood pulp sheets can be produced by a chemical,
thermomechanical, or chemithermomechanical process. Suitable wood
pulp sheets may also be pretreated prior to the application of the
saccharide in accordance with the present invention. Examples of
suitable pretreatments include cross-linking the fibers, treating
the fibers to effect their wettability, or bleaching the fibers.
Additionally, other fibers, natural or synthetic, may be included
in the pulp sheet. Examples of other fibers include silk, wool,
linen, rayon, lyocell, polyethylene, polypropylene, polyester,
polyamide, and the like.
[0028] As used herein, the term knot refers to a mass of individual
fibers that have not been separated from each other. Fiberized
masses of fibers having lower knot levels are preferred over
fiberized masses that have higher knot levels because the presence
of knots generally viewed as preventing the fibers from performing
their functions of distribution of any superabsorbent polymer (if
present), providing pad integrity, fluid distribution and liquid
holding capacity. Excessive knots are also viewed as unsightly and
detrimental to the visual acceptance of the finished product.
Saccharide-treated cellulose pulp sheets of the present invention
when fiberized under standard Kamas conditions described below,
yield less than 20 wt. % knots as determined by the test described
below in more detail. These fibers may be densified via the
application of pressure in a press or nip-roll.
[0029] The solids content of the saccharide applied to the
cellulose pulp sheet is less than about 65 wt. %. When the
saccharide has a solids content less than about 65 wt. %, the
cellulose pulp sheet treated with the saccharide when fiberized
under standard Kamas conditions yields less than about 20 wt. %
knots. When corn syrup, high fructose corn syrup, honey, or sucrose
is used as the source of saccharide, it can be diluted with water
in order to reduce the solids content to below about 65 wt. %.
Preferably, no other agents are used to dilute the saccharide, such
as organic solvents so that the cellulose pulp sheets of the
present invention preferably consist only of cellulose fibers,
saccharide, and water introduced to the cellulose fibers with the
saccharide and water that is present as moisture in the cellulose
pulp sheet.
[0030] With the particular saccharides corn syrup and high fructose
corn syrup, which are typically available with a solids content on
the order of 70% or greater, diluting the corn syrup or high
fructose corn syrup to a solids content of less than about 65 wt. %
surprisingly results in a cellulose pulp sheet that when fiberized
under standard Kamas conditions yields less than 20 wt. % knots.
Heat treating saccharide treated cellulose pulp sheets as described
in the examples also results in treated sheets that can be
fiberized under standard Kamas conditions yielding less than 20 wt.
% knots. Furthermore, as illustrated in the examples, treated pulp
sheets which are not fiberized for 1-2 months after saccharide
treatment yield less than 20 wt. % knots.
[0031] In accordance with the present invention, the amount of
saccharide added to the cellulose pulp sheet can vary across a wide
range. On the upper end, the amount of saccharide added to the
cellulose pulp sheet is generally limited to an amount that
maintains the water content of the cellulose pulp sheet below about
20 wt. %. When the saccharide has a solid contents less than 65 wt.
% as described above, amounts of saccharide up to about 65 wt. %
based on the dry weight of the fiber can be added. Adding lesser
amounts of saccharide to the cellulose pulp sheet will provide the
improved densification and softness properties of the fluff
produced from such saccharide treated cellulose pulp sheet.
[0032] In preferred embodiments of the present invention, the
saccharide is added to the cellulose pulp sheet in an amount that
results in a dry solids content of less than about 20 wt. % based
on the weight of dry cellulose fiber in the treated cellulose pulp
sheet and more preferably less than 10 wt. %. As noted above, such
dry solids content can be achieved using a saccharide that has been
diluted with water. The extent of the dilution of the saccharide,
and therefore the ratio of water to saccharide solids, should be
selected so that the desired degree of saccharide solids can be
achieved without introducing so much water that the pulp sheet
becomes difficult to fiberize due to the addition of excess water.
It is well known that pulp which is too wet is difficult to
fiberize. The dilution should not be so great that when the
saccharide solution is added to the cellulose pulp sheet to achieve
the desired saccharide content, the saccharide-treated cellulose
pulp sheet yields more than 20 wt. % knots when fiberized under
standard Kamas conditions. A water content of the cellulose pulp
sheet after being treated with saccharide of about 10 wt. % based
on the weight of the total product is exemplary. Lower water
contents are contemplated with an upper limit of about 15-20 wt. %
based on the need to avoid poor fiberization.
[0033] Sufficient amounts of saccharide should be added to the
cellulose pulp so that when the cellulose pulp is fiberized, the
knot yield is below 20 wt. % and the resulting fibers exhibit ease
of densification properties and/or softness properties that are
superior to the ease of densification and softness properties of
the cellulose pulp without being treated with a saccharide.
Improved ease of densification properties result when about 5.0 wt.
% dry saccharide solids based on the dry cellulose fiber content of
the pulp sheet. Lower amounts of dry saccharide solids in the
treated cellulose sheets are within the present invention; for
example, amounts down to about 0.5 wt. % based on the dry fiber
content of the cellulose pulp are within the scope of the present
invention.
[0034] The saccharides are applied to the cellulose pulp sheet in a
number of different ways. The present invention is not limited to
any particular application technique. Examples of suitable
application techniques include spraying, rolling, dipping, and the
like. The saccharide can be applied to one or both sides of the
cellulose pulp sheet.
[0035] The procedure for determining knot yield of a
saccharide-treated pulp sheet is described below. The cellulose
pulp sheet is first subjected to the standard Kamas fiberization
conditions described below at about 70.degree. F. and relative
humidity of about 50%. Standard Kamas fiberization conditions are
carried out in a Kamas Cell Mill.RTM. laboratory hammermill
fiberization unit available from Kamas Industri AB of Sweden
(typ--Kvarn H. 01 M-NR 7.102.2516). The hammermill is operated at
the following conditions:
1 Parameter Setting Breaker bar gap 4 mm Exit screen hole size 19
mm Rotor speed 3,000 rpm Pulp sheet mass feed rate 2.75 to 2.8
grams per second Pulp sheet width 2 inches Hammermill rotor
diameter 12 inches (tip-to-tip distance) Number of hammers 4 around
circumference of rotor
[0036] The fiberized pulp is collected and tested for knot yield in
the following manner.
[0037] The knot content is determined using a sonic knot device
used to classify fiberized pulp into fractions based on screen mesh
size. The first collected fraction is the large knots and is
defined as that material that is captured by a No. 5 mesh screen.
The second fraction is the intermediate knots and is defined as the
material captured by a No. 8 mesh screen. The third fraction is the
smaller knots and is defined as the material captured by a No. 12
mesh screen. The fourth fraction is the accepts, or the singulated
fibers, and is defined as that material that passes through the No.
5, No. 8, and No. 12 mesh screens, but is captured by a No. 60 mesh
screen. The separation is accomplished by sound waves generated by
a speaker that are imposed upon a pre-weighed sample of the
fiberized saccharide-treated cellulose pulp placed on the first
layer No. 5 mesh screen that is near the top of a separation column
where the speaker sits at the very top. After a set period of time,
each fraction from the No. 5, No. 8, and No. 12 screens is removed
from the separation column and is added back to the No. 5 screen
for a second pass through the sonic test. After the set period of
time, each fraction from the No. 5, No. 8, and No. 12 screens is
removed from the separation column and weighed to obtain the weight
fraction of knots. For the purposes of the present invention, the
predetermined time was 6 minutes.
[0038] Referring to FIG. 3, a more detailed description of the
apparatus used for the sonic knot test is provided.
[0039] The device consists of a loudspeaker 1a housed inside a
polycarbonate cylinder 1b. The loudspeaker is a Radio Shack 12"
diameter model (Cat. No. 40-1034, power handling capability=75 W
RMS and 150 W max., with a nominal impedance of 8 Ohms.). Under
operation it is fed by an amplifier which results in the generation
of a square wave input signal (of 26 volts peak-to-peak) set to
result in a continuous ultra-low frequency tone at 13.0-13.6 Hz.
Sound from the speaker passes through a loose sheet of plastic bag
material 2 that is sealed against the walls of the polycarbonate
cylinder to protect the speaker from the fluff fibers.
[0040] The polycarbonate cylinder is connected via two spacer discs
3 to a Tyler equivalent 5 mesh screen 4 (USA Standard testing
sieve, ASTME-11 specification, No. 5). Which in turn is connected
to two more spacer discs 5 and 6, an 8 mesh screen 7, two more
spacer discs 8 and 9, a 12 mesh screen 10, then a 60 mesh screen
11, and finally a 200 mesh screen 12. All screens and spacers are
from the same manufacturer and are of equal 12" diameter and "nest"
tightly into one another to create a unified stack. A good seal
between the various screens and spacers is maintained with tape and
"O-rings" to prevent air leaks. At the base of the stack the exit
from the 200 mesh screen is sealed by a plastic bag 13 containing a
hole 14 in its wall of .about.1.25" diameter (this allows escape of
air from the stack). The device is supported by resting on the rim
of screen 12.
[0041] Air is supplied to the unit at three locations 15, 16, and
17 into spacers 3, 5, and 9, respectively, via small (.about.3-5 mm
diameter) pipes fitted with fan type spray nozzles at their ends.
The function of the air is to assist in gently separating the fiber
mass as it is processed. Just before the start of each sonic cycle,
about 1 to 3 ml of anti-static solution ("Heavy Duty Staticide"
#2002 from VWR Company Cat. #58611-225) is pumped into tube 15 by a
peristaltic pump at 19. When the airflow is turned on at the start
of the sonic cycle the anti-static solution in tube 15 is ejected
via a spray nozzle located on the end of tube 15 as a fine mist
spray over the pulp 18 which is lying on the 5 mesh screen below.
The function of the anti-static is to prevent static
clumping/clinging together of the fibers.
[0042] Air flow rate is targeted to be 5.4 to 5.6 SCFM at location
15; 4.3 to 4.6 SCFM at location 16, and 2.5 to 2.8 SCFM at location
17. The air supply to the unit is at .about.6-7% relative humidity
(RH) at room temperature. The whole unit is contained in a sound
proof box operated in a lab at 50% RH and 70-75F.
[0043] Prior to initiation of the sonic knot test, the samples of
fiberized cellulose prepared from the pulp sheets treated with
saccharide are conditioned at 50 percent relative humidity at
23.degree. C., for a minimum of 4 hours. Five gram samples of the
fiberized cellulose pulp are employed in 3 separate runs. As a
further preparatory matter, a 5 gram sample of fiberized cellulose
pulp that has not been treated with a saccharide is run through the
different screens in order to distribute anti-static material
throughout the different screens.
[0044] The incoming air pressure should be 20-25 psi at rest, and
20-24 psi when running. Pressure settings for the respective
screens are as follows:
2 The Screen Air Flow (SCFM) 5 mesh 5.4 to 5.6 8 mesh 4.3 to 4.6 12
mesh 2.5 to 2.8
[0045] The knot determination procedure begins by running two 5
gram samples of a control cellulose pulp (Weyerhaeuser Company CF
416 from Columbus, Miss.) that has been fiberized under the
standard Kamas conditions. The weight of the two runs for each
screen is recorded and then the weights for both runs is added
together and the percentage of knot yield is calculated as
described below in more detail. The collected knots for the control
samples are not rerun. When the control samples fall within the
ranges of 7-8 wt. % knots proceed on to the test of the treated
samples. Attaining this level of knots on the CF 416 sample ensures
that the sonic unit, air flow, and other parameters, are operating
properly. If the control samples do not fall within the established
ranges for knots, adjust the equipment so that it does. Adjustments
can be made to the air flows and voltage driving the square wave to
the speaker to achieve operation within the desired range.
[0046] Once the sonic fractionator has been calibrated as described
above, the test samples of the fiberized treated cellulose pulp
sheet can be evaluated in the following manner. As generally
described above, the overall procedure is to run three 5 gram
samples of the fiberized cellulose pulp, collect the knots from all
three runs, and then run the collected knots combined for a second
pass.
[0047] The first 5 gram sample of fiberized pulp is placed on the
top screen and distributed uniformly by hand without compacting.
The fiberized pulp should be broken up into at least 30 to 40 small
pieces. The speaker assembly is placed on top of the upper screen.
The anti-static material delivers 1-3 ml of liquid over the sample.
The fractionator is started and cycled for six minutes, after which
it is stopped. After the cycle stops, the anti-static pump delivers
1 to 3 ml of anti-static material into the airstream, preparing the
equipment for the next sample to be tested. After the cycle is
stopped, the knots collected on the 5, 18, and 12 mesh screens are
gathered by hand and weighed separately to the nearest 0.01 gram.
The knots are saved from all screens for the final pass described
below. Care should be taken not to bang the screens on the counter
to remove knots. Cellulose pulp stuck on the bottom or around the
top edges of a screen should be added into the next screen in
sequence. The accepts collected on the 60 mesh screen should be
gathered by hand and weighed to the nearest 0.01 gram and saved for
reweighing after the final pass described below. Fines collected on
the 200 mesh screen should be gathered gently first by brush to
collect as much as possible into one area on the edge of the
screen. Once gathered, the screen can be turned upside down and
tapped on a counter gently so that the fines fall out. The fines
should be gathered with fingers or a plastic scraper and weighed to
the nearest 0.1 gram and saved for reweighing after the final pass
described below. The inside surface of the speaker assembly that
fits on top of the 5 mesh screen should be checked visually or by
feel for collection of pulp. Any pulp collected there should be
removed after the end of each cycle and saved for later. At the end
of the three 5.0 gram runs, the pulp collected from the speaker
should be combined with the collected knots to be rerun.
[0048] The foregoing is then repeated with each of the addition two
5.0 gram samples. All the knots collected from the 5, 8, and 12
mesh screens from each of the three runs is then combined and
placed into the top 5 mesh screen and distributed evenly. Any pulp
collected from the inside of the speaker assembly as described
above should be added to the knots on the top screen. The collected
pulp should be broken up into small pieces.
[0049] The fractionator should then be run for one more six minute
cycle. When the cycle stops, the knots collected on the 5, 8, and
12 mesh screens should be gathered by hand and weighed separately
to the nearest 0.01 gram. The accepts on the 60 mesh screen should
be collected after this final run and combined with the saved
accepts from the first runs described above. The combined saved
accepts should be weighed to the nearest 0.01 grams.
[0050] The fines collected on the 200 mesh screen during this final
pass should be combined with the saved fines from the first passes
described above. The combined fines should then be weighed to the
nearest 0.01 gram.
[0051] Again, the inside surface of the speaker assembly should be
checked for any miscellaneous pulp that has collected there. This
collected pulp should be weighed to the nearest 0.01 gram and
recorded as Miscellaneous Weight.
[0052] To determine the percent knot yield by the pulp sample, an
Adjusted Starting Weight for the pulp should be determined by
subtracting the Miscellaneous Weight from the Total Starting Pulp
Weight:
Adjusted Starting Weight=Total Starting Pulp Weight-Miscellaneous
Weight (1)
[0053] To determine the percent knot yield, divide the weight of
the knots after the final run by the Adjusted Starting Weight and
multiply by 100 to provide a percentage using the following
formula:
(Final Recorded Weight of Knots.div.Adjusted Starting
Weight).times.100=% Knot Yield (2)
[0054] The foregoing calculation is done for each of the knot
weights for their respective 5, 8, and 12 mesh screens. The total
knot yield is then determined by adding the percentages of the 5,
8, and 12 mesh screens together.
[0055] Cellulose pulp sheets treated with a saccharide in
accordance with the present invention when fiberized under standard
Kamas fiberization conditions yields less than 20 wt. % knots using
the test procedure described above. The fiberized pulp of the
present invention exhibits densification and softness properties
that are improved compared to fibers produced from the same
cellulose pulp sheets that have not been treated in accordance with
the present invention. The preparation of treated cellulose pulp
sheets of the present invention and the sheet densification and
softness properties of the fiberized pulp sheets are described in
more detail in the examples that follow.
EXAMPLE 1
Preparation of High Fructose Corn Syrup Treated Cellulose Pulp
[0056] Southern Pine fluff in sheet form available from
Weyerhaeuser Company under the designation NB 416 from New Bern,
N.C. with a starting moisture content of 6% by weight (based on
total sheet weight) was coated in a Black Brothers gravure-type
roll coater with a solution of corn syrup. The gravure coater
results in the application of a uniform coating of the corn syrup
solution over one entire surface of the pulp sheet from where it is
rapidly soaked up by the sheet. The corn syrup was a high fructose
corn syrup available from Archer-Daniels Midland Company of
Decatur, Ill. under the trademark CORN SWEET.RTM. 42. The corn
syrup had a solids content of 71% with the balance being water.
This corn syrup was diluted with water to a solid content of 54.5
wt. % based on total solution weight before its application to the
wood pulp sheet. This 54.5 wt. % solution was applied to the wood
pulp sheet at a rate of 15.5 parts solution to 100 parts of pulp
sheet, resulting in a loading of active on a (dry basis) corn syrup
solids of 9 wt. % based on the dry fiber content of the pulp sheet
(equivalent to 7.3 wt. % corn syrup solids based on the total final
product weight). The final total moisture content of the wood pulp
cellulose sheet treated with corn syrup is 11.3 wt. % based on the
total final product weight.
[0057] The treated sheet was stored in a plastic zippered bag for
24 hours at room temperature to allow the added moisture to migrate
and reach equilibrium within the whole sheet. The sheet was then
fiberized in a laboratory Kamas Mill Hammermill operating under the
standard Kamas fiberization conditions described above. Knot
content was measured using the sonic knot device described above
and resulted in a knot yield of 19% by weight.
EXAMPLE 2
Preparation of High Fructose Corn Syrup Treated Cellulose Pulp
Sheet Using Diluted Corn Syrup
[0058] The procedure in Example 1 was reproduced except that the
CORN SWEET.RTM. 42 corn syrup was diluted to a solids content of
52.2 wt. % based on total solution weight using water. 10.58 parts
of the corn syrup solution were added to 100 parts of the NB 416
wood pulp cellulose sheet. This resulted in a loading of active (on
a dry basis) corn syrup solids of 5.88 wt. % based on the dry fiber
content (or an equivalent 5.0 wt. % corn syrup solid based on the
total final product weight). The final total moisture content of
the wood pulp sheet treated with corn syrup was 10 wt. % based on
the total final product weight. Knot yield after fiberization was
16% for the above sample.
EXAMPLE 3
Preparation of High Fructose Corn Syrup Treated Cellulose Pulp
Sheet Treated With Heat
[0059] An additional sample of the corn syrup treated wood pulp of
Example 1 was further evaluated on a Fitz Hammermill feeding an
M&J continuous airlaid pad forming device. A portion of the
corn syrup treated pulp sheet of Example 1 was first run as-is on
the Fitz Hammermill. The resultant fiberized pulp was collected.
The remaining portions of the treated pulp sheet were sealed inside
plastic bags double layered to prevent moisture loss and heated for
24 hours at 150.degree. F. in a laboratory oven. After heat
treatment, the pulp sheet was allowed to cool back to room
temperature while still in the plastic bags and was then fiberized
on the Fitz Hammermill under the same conditions used for the
non-heat-treated pulp. Both heated and non-heated pulps were tested
for knot content by the sonic method described above. The knot
content of the two samples was similar; however, the physical
appearance of the pulp which received the heat treatment exhibited
a marked lack of fiber clumping as compared to the unheated sample.
The absence of fiber clumping for the heated sample is evidence of
further improvement of fiberization quality (over that which is
indicated by sonic knots alone). Absence of fiber clumps indicates
the positive effect of heating during the period where the corn
syrup is soaking into and distributing itself amongst the fibers of
the sheet.
EXAMPLE 4
Preparation of High Fructose Corn Syrup Treated Cellulose Pulp
Sheet After Storing at Room Temperature
[0060] An NB 416 wood pulp sheet is treated with high fructose corn
syrup in accordance with Example 1 described above. The treated
sheet is stored at room temperature in zippered plastic bags to
prevent moisture loss for a period of two months. After the storage
time, the fiberization characteristics are retested by Kamas
fiberization using the standard Kamas fiberization conditions and
the knot content is evaluated using the sonic method. Knot content
of the treated sheet was 12 wt. %, a significant drop compared to
the knot content of the sheet tested in Example 1. The foregoing
suggests that prolonged storage at room temperature of a wood pulp
cellulose sheet treated with the corn syrup of Example 1 can effect
the fiberization properties of the sample.
EXAMPLE 5
Densification and Softness Properties of Fibers Produced From High
Fructose Corn Syrup Treated Cellulose Pulp Sheets
[0061] High fructose corn syrup treated wood pulp sheets of NB 416
were prepared according to Example 2. The treated sheets were
fiberized in a laboratory hammermill different from the Kamas Cell
Mill.RTM. described above, but one which closer resembles the
set-up of hammermills used in commercial fiberization operations.
The fiberized pulp was fed to a commercial airlaid rotating
circular pocket former of the type used on commercial diaper
manufacturing lines.
[0062] The above fiberized corn syrup treated pulp and untreated
pulp were airlaid into pads of about 400 grams per square meter
basis weight, measuring about 12 inches long and five inches wide.
The pads were densified in a hydraulic flat press under loads of
either 0 psi, 50 psi, 100 psi, and 150 psi. The pressure was only
held momentarily and then released. Different pads were used for
each of the successively higher loads. Caliper (thickness) of the
pads was determined using a caliper gage with a wide "foot" design
to apply only moderate pressure to the pad (i.e., it does not
materially densify the pad in the act of determining caliper). The
densities of the pads were calculated from the caliper and basis
weight measurements.
[0063] Results of the density measurements versus applied pressure
are shown in FIG. 1 and show that the high fructose corn syrup
treated pulp attains a higher density for a given pressure compared
to the untreated pulp.
[0064] The softness of the airlaid pads was determined by measuring
a cantilever "bend length" for the pad as the long axis of the pad
is extended out over a 45.degree. inclined plane. The distance
between the edge over which the pad is pushed and the outermost tip
of the pad where it touches down on the 45.degree. inclined plane
is recorded in centimeters as the "bend length," and provides a
measure of relative softness. A long bend length implies a stiff
(or less soft) pad. Results of the softness test (across the range
of applied pressures) are shown in FIG. 2 and illustrate that the
high fructose corn syrup treated wood pulp fibers has softness
properties superior to those of the untreated wood pulp cellulose
fibers.
EXAMPLE 6
Preparation of Honey and Sucrose Treated Cellulose Pulp Sheets
[0065] Pieces of southern pine pulp in sheet form available from
Weyerhaeuser Company under the designation NB 416 from New Bern,
N.C., having a starting moisture content of 6 wt. % based on the
total sheet weight, were prepared measuring about 4 inches wide by
20 inches long. One hundred parts of the cellulose pulp sheet was
coated with one of the following solutions using a laboratory
syringe. The saccharide containing solution was applied on to one
side of the cellulose pulp sheet. The first solution was an aqueous
solution containing 44 wt. % solids of common table honey. The
second solution was an aqueous solution containing 50 wt. % solids
of white table sugar, i.e., sucrose. The honey containing solution
was applied in an amount of 11.8 parts and the sucrose containing
solution was applied to a separate sample of cellulose pulp sheet
in the amount of 10.4 parts.
[0066] The treated sheets were placed in a sealed plastic bag for
24 hours and fiberized under the standard Kamas fiberization
conditions. Knots were determined as described above and resulted
in yields of 17 wt. % for the cellulose pulp sheet treated with the
honey solution, and 15 wt. % for the cellulose pulp sheet treated
with the sucrose solution.
[0067] Ease of densification for each of the two samples described
above was determined by first preparing freshly fluffed material in
a laboratory Waring blender, running for about 30-60 seconds on
high speed, using approximately 1.5 grams of the treated pulp sheet
per sample. The resulting 1.5 grams of fluff was formed into
circular pads measuring about 7 cm in diameter using a laboratory
airlaid pad former. The initial weight and caliper of the pads were
determined and then each pad was subjected to momentary pressure in
a flat press (laboratory Carver press) at each of three,
successively higher pressures of 50 psi, 100 psi, and 150 psi.
After pressing at each pressure, the caliper was redetermined using
a caliper gauge that applies a modest pressure so that the pad is
not materially compressed and these readings used to calculate
density. The results are illustrated in FIG. 5 and illustrate the
densification properties of fibers prepared from cellulose pulp
sheets treated with a saccharide in accordance with the present
invention versus fibers produced by fiberizing the NB 416 pulp
sheet described above.
[0068] The foregoing examples describe the present invention in the
context of a particular saccharide, namely, high fructose corn
syrup. It should be understood that the present invention is not
necessarily limited to high fructose corn syrup and that other
saccharides, such as those of Example 6, are considered to be
within the scope of the present invention.
[0069] FIG. 4 illustrates a wet laid sheet manufacturing line such
as a pulp sheet manufacturing line 10 for manufacturing the treated
cellulose pulp sheets of the present invention. In this
manufacturing line, a pulp slurry 12 is delivered from a headbox 14
through a slice 16 and onto a Fourdrinier wire 18. The pulp slurry
12 typically includes wood pulp fibers and may also include
synthetic or other non-cellulose fibers as part of the slurry.
Water is drawn from the pulp deposited on wire 18 by a conventional
vacuum system, not shown, leaving a deposited pulp sheet 20 which
is carried through a dewatering station 22, illustrated in this
case as two sets of calendar rolls 24, 26 each defining a
respective nip through which the pulp sheet or mat 20 passes. From
the dewatering station, the pulp sheet 20 enters a drying section
30. In a conventional pulp sheet manufacturing line, drying section
30 may include multiple canister dryers with the pulp mat 20
following a serpentine path around the respective canister dryers
and emerging as a dried sheet or mat 32 from the outlet of the
drying section 30. Other alternate drying mechanisms, alone or in
addition to canister dryers, may be included in the drying stage
30. The dried pulp sheet 32 has a maximum moisture content pursuant
to the manufacturer's specifications. Typically, the maximum
moisture content is no more than 10% by weight of the fibers and
most preferably no more than about 6% to 8% by weight. The dried
sheet 32 is taken up on a roll 40 for transportation to a remote
location, that is, one separate from the pulp sheet manufacturing
line, such as at a user's plant for use in manufacturing products.
The dried pulp sheets have a basis weight of about 200 g/m.sup.2 to
about 1000 g/m.sup.2 or more and a density on the order of at least
about 0.3 g/cm.sup.3 and more preferably 0.5 g/cm.sup.3. Dried
cellulose pulp sheets having the foregoing basis weights and
densities that are useful in the present invention are structurally
distinct from lighter basis weight sheets of wet laid or airlaid
wood pulp fibers such as crepe paper, tissue paper, paper towels,
or other types of paper-like wet laid or airlaid webs of cellulose
fibers. Alternatively, the saccharide can be applied in a
manufacturing line that does not employ a Fourdrinier wire and
produces cellulose pulp in non-sheet form, such as chunks or slabs,
that can be collected in a baling apparatus 42 from which bales of
the pulp 44 are obtained for transport to a remote location. The
cellulose pulp in non-sheet form useful in the present invention
has a density that is greater than about 0.3 g/m.sup.3 and more
preferably greater than about 0.5 g/m.sup.3.
[0070] A saccharide of the type explained in detail below is
applied to the pulp sheet from one or more saccharide applying
devices, one of which is indicated at 50 in FIG. 4. Any applying
device may be used, such as streamers, sprayers, roll coaters,
curtain coaters, immersion applicators, or the like. Sprayers are
typically easier to utilize and incorporate into a pulp-sheet
manufacturing line. As indicated by the arrows 52, 54, and 56, the
fiber treatment composition may be applied at various locations or
at multiple locations on the pulp sheet manufacturing line, such as
ahead of the drying stage 30 (indicated by line 52), intermediate
the drying stage 30 (as indicated by line 54), or downstream from
the drying stage 30 (as indicated by the line 56). Application of
the saccharide after some drying has taken place, for example at
location 54, is preferable and more preferably at 56 after the
drying stage. If the saccharide is applied at location 56 in an
amount which would cause the moisture content of the sheet to
exceed the desired maximum level, an additional drying stage (not
shown) may be included in the pulp manufacturing line to bring the
moisture content down to the desired level.
[0071] The rolls 40 or bales 44 of the treated wet laid web of
fibers may be transported to a remote location for use by a user.
These rolls or bales are then refiberized by a fiberizing device,
such as a hammermill which may be used alone or in conjunction with
other devices such as picker rolls or the like for breaking up the
sheet 32 or bales 42 into individual fibers. Depending on the end
use, the individualized fibers may be combined with particulate
material, such as superabsorbent particles, and/or airlaid into a
web and densified.
[0072] With this approach, the end user of the treated fibers may
readily select particles to be combined with the fibers. The user
has flexibility in air laying or otherwise processing the treated
fibers of the present invention into a finished product.
[0073] While the preferred embodiment of the invention has been
illustrated and described, it will be appreciated that various
changes can be made therein without departing from the spirit and
scope of the invention.
* * * * *