U.S. patent application number 11/349862 was filed with the patent office on 2006-06-15 for wet strength and softness enhancement of paper products.
Invention is credited to Bruce J. Kokko, David W. White.
Application Number | 20060124264 11/349862 |
Document ID | / |
Family ID | 32908303 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060124264 |
Kind Code |
A1 |
Kokko; Bruce J. ; et
al. |
June 15, 2006 |
Wet strength and softness enhancement of paper products
Abstract
A method for making paper to enhance its wet strength includes
adding separately to a cellulosic paper pulp furnish the following
additives to form a treated pulp: a cationic wet strength resin
whose cationic sites bond to anionic sites of cellulose fibers
contained in the paper pulp furnish, and a hydrophobically modified
anionic polyelectrolyte whose anionic sites bond with cationic
sites of the cationic wet strength resin.
Inventors: |
Kokko; Bruce J.; (Neenah,
WI) ; White; David W.; (Clintonville, WI) |
Correspondence
Address: |
DILWORTH & BARRESE, LLP
333 EARLE OVINGTON BLVD.
UNIONDALE
NY
11553
US
|
Family ID: |
32908303 |
Appl. No.: |
11/349862 |
Filed: |
February 8, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10413693 |
Apr 15, 2003 |
|
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11349862 |
Feb 8, 2006 |
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Current U.S.
Class: |
162/167 |
Current CPC
Class: |
D21H 17/64 20130101;
C08F 8/32 20130101; C08F 8/32 20130101; C08F 8/44 20130101; D21H
21/22 20130101; C08F 8/44 20130101; D21H 17/43 20130101; C08F 8/32
20130101; D21H 17/71 20130101; C08F 8/44 20130101; D21H 23/765
20130101; C08F 222/06 20130101; C08F 222/06 20130101; C08F 210/02
20130101; C08F 8/32 20130101; C08F 210/02 20130101; C08F 8/32
20130101 |
Class at
Publication: |
162/167 |
International
Class: |
D21H 23/00 20060101
D21H023/00 |
Claims
1-18. (canceled)
19. A paper product comprising: a) at least one cellulosic
component possessing anionic sites; b) the reaction product of i.
cationic wet strength resin possessing cationic sites, and ii.
anionic polyelectrolyte possessing anionic sites and hydrophobic
groups.
20. The paper product of claim 19 wherein the cationic wet strength
resin has azetidinium or epoxide functionality.
21. The paper product of claim 20 wherein the cationic wet strength
resin is a polymeric amine epichlorohydrin resin selected from the
groups consisting of polyamide-epichlorohydrin resin, a
polyalkylene polyamine-epichlorohydrin resin,
polyamidoamine-epichlorohydrin resin and an amine
polymer-epichlorohydrin resin.
22. The paper product of claim 19 wherein the anionic
polyelectrolyte is made by reacting a polymeric compound having
anhydride groups with an amine having the formula: HNR.sup.1R.sup.2
wherein R.sup.1 and R.sup.2 are each selected from the group
consisting of hydrogen and a saturated or unsaturated, straight
chain or branched aliphatic group having from 1 to 36 carbon atoms,
with the proviso that at least one of R.sup.1 and R.sup.2 is a
hydrophobic saturated or unsaturated, straight chain or branched
aliphatic group having from about 8 to about 36 carbon atoms.
23. The paper product of claim 22 wherein the hydrophobic aliphatic
group possesses from about 12 to about 24 carbon atoms.
24. The paper product of claim 22 wherein the amine is selected
from the group consisting of octylamine, decylamine, dodecylamine,
tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine,
heptadecylamine, octadecylamine, nonadecylamine, eicosylamine,
N-methyl-N-octylamine, N-methyl-N-decylamine,
N-methyl-N-dodecylamine, N-methyl-N-tridecylamine,
N-methyl-N-tetradecylamine, N-methyl-N-pentadecylamine,
N-methyl-N-hexadecylamine, N-methyl-N-heptadecylamine,
N-methyl-N-octadecylamine, N-methyl-N-nonadecylamine,
N-methyl-N-eicosylamine, N-ethyl-N-octylamine,
N-ethyl-N-decylamine, N-ethyl-N-dodecylamine,
N-ethyl-N-tridecylamine, N-ethyl-N-tetradecylamine,
N-ethyl-N-pentadecylamine, N-ethyl-N-hexadecylamine,
N-ethyl-N-heptadecylamine, N-ethyl-N-octadecylamine,
N-ethyl-N-nonadecylamine and N-ethyl-N-eicosylamine and mixtures
thereof.
25. The paper product of claim 22 wherein the polymeric compound
having anhydride groups is a copolymer of ethylene and maleic
anhydride and the amine is octadecylamine or
N-methyl-N-octadecylamine.
26. The paper product of claim 25 wherein the anionic
polyelectrolyte includes from about 5 mole percent to about 10 mole
percent octadecylamide or N-methyl-N-octadecylamide units.
27. The paper product of claim 22 wherein the anionic
polyelectrolyte is made by reacting a polyolefin-co-maleic
anhydride with the amine in a solvent to form an intermediate
product, separating the intermediate product from the solvent and
dissolving the intermediate product in an aqueous alkali solution
to form a gel, and then treating the gel with an alkali halide
solution.
28. The paper product of claim 19 wherein the anionic
polyelectrolyte is made from a copolymer of an olefin and an
unsaturated organic anhydride, wherein said olefin contains from
about 8 to about 36 carbon atoms.
29. The paper product of claim 28 wherein the olefin is octadecene
and the unsaturated organic anhydride is maleic acid.
30. The paper product of claim 19 wherein the cellulosic component
is derived from kraft pulp.
31. The paper product of claim 19 wherein the anionic
polyelectrolyte is combined with at least one non-substantive
softener.
32. The paper product of claim 31 wherein the non-substantive
softener is selected from the group consisting of fatty alcohol,
fatty acid ester, fatty alcohol ester, alkoxylated fatty alcohol,
esters of polyethylene glycol and/or polypropylene glycol with
fatty acids, Guerbet alcohols and mixtures thereof.
33. The paper product of claim 32 wherein the alkoxylated fatty
alcohol is an ethoxylated, propoxylated, or ethoxylated and
propoxylated fatty alcohol and the fatty acid ester is a sorbitan
fatty acid ester or a fatty acid ester of polyethylene glycol
and/or polypropylene glycol.
34. A hydrophobically modified anionic polyelectrolyte made by
reacting a polymeric compound having anhydride groups with an amine
having the formula: HNR.sup.1R.sup.2 wherein R.sup.1 and R.sup.2
are each selected from the group consisting of hydrogen and a
saturated or unsaturated, straight chain or branched aliphatic
group having from 1 to 36 carbon atoms, with the proviso that at
least one of R.sup.1 and R.sup.2 is a hydrophobic saturated or
unsaturated, straight chain or branched aliphatic group having from
about 8 to about 36 carbon atoms.
35. The hydrophobically modified polyelectrolyte of claim 34
wherein the hydrophobic aliphatic group possesses from about 12 to
about 24 carbon atoms.
36. The hydrophobically modified anionic polyelectrolyte of claim
34 wherein the amine is selected from the group consisting of
octylamine, decylamine, dodecylamine, tridecylamine,
tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine,
octadecylamine, nonadecylamine, eicosylamine, -methyl-N-octylamine,
N-methyl-N-decylamine, N-methyl-N-dodecylamine,
-methyl-N-tridecylamine, N-methyl-N-tetradecylamine,
N-methyl-N-pentadecylamine, N-methyl-N-hexadecylamine,
N-methyl-N-heptadecylamine, N-methyl-N-octadecylamine,
N-methyl-N-nonadecylamine, N-methyl-N-eicosylamine,
N-ethyl-N-octylamine, N-ethyl-N-decylamine, N-ethyl-N-dodecylamine,
-ethyl-N-tridecylamine, N-ethyl-N-tetradecylamine,
N-ethyl-N-pentadecylamine, N-ethyl-N-hexadecylamine,
N-ethyl-N-heptadecylamine, N-ethyl-N-octadecylamine,
N-ethyl-N-nonadecylamine and N-ethyl-N-eicosylamine and mixtures
thereof.
37. The hydrophobically modified polyelectrolyte of claim 34
wherein said hydrophobically modified anionic polyelectrolyte
includes from about 5 mole percent to about 10 mole percent
octadecylamide or N-methyl-N-octadecylamide units.
38. The hydrophobically modified polyelectrolyte of claim 34
wherein the product of the reaction of the polymeric compound and
the amine is further reacted with an alkali in aqueous
solution.
39. A hydrophobically modified anionic polyelectrolyte made by
reacting a polymeric compound having anhydride groups and
hydrophobic groups with an alkali in aqueous solution.
40. The hydrophobically modified anionic polyelectrolyte of claim
39 wherein the hydrophobic groups are saturated or unsaturated,
straight chain or branched aliphatic groups each having from about
8 to about 36 carbon atoms.
41. A composition for enhancing the wet strength of a cellulosic
paper which comprises: a) anionic polyelectrolyte possessing
hydrophobic groups and anionic sites capable of bonding to unbound
cationic sites in a cationic wet strength resin; b) an alkali
compound; and c) water.
42. The composition of claim 41 wherein the anionic polyelectrolyte
is made by reacting a polymeric compound having anhydride groups
with an amine having the formula: HNR.sup.1R.sup.2 wherein R.sup.1
and R.sup.2 are each selected from the group consisting of hydrogen
and a saturated or unsaturated, straight chain or branched
aliphatic group having from 1 to 36 carbon atoms, with the proviso
that at least one of R.sup.1 and R.sup.2 is a hydrophobic saturated
or unsaturated, straight chain or branched aliphatic group having
from about 8 to about 36 carbon atoms.
43. The composition of claim 42 wherein the hydrophobic aliphatic
group possesses from about 12 to about 24 carbon atoms.
44. The composition of claim 42 wherein the amine is selected from
the group consisting of octylamine, decylamine, dodecylamine,
tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine,
heptadecylamine, octadecylamine, nonadecylamine, eicosylamine,
N-methyl-N-octylamine, N-methyl-N-decylamine,
N-methyl-N-dodecylamine, N-methyl-N-tridecylamine,
N-methyl-N-tetradecylamine, N-methyl-N-pentadecylamine,
N-methyl-N-hexadecylamine, N-methyl-N-heptadecylamine,
N-methyl-N-octadecylamine, N-methyl-N-nonadecylamine,
N-methyl-N-eicosylamine, N-ethyl-N-octylamine,
N-ethyl-N-decylamine, N-ethyl-N-dodecylamine,
-ethyl-N-tridecylamine, N-ethyl-N-tetradecylamine,
N-ethyl-N-pentadecylamine, N-ethyl-N-hexadecylamine,
N-ethyl-N-heptadecylamine, N-ethyl-N-octadecylamine,
N-ethyl-N-nonadecylamine and N-ethyl-N-eicosylamine and mixtures
thereof.
45. The composition of claim 42 wherein the polymeric compound
having anhydride groups is a copolymer of ethylene and maleic
anhydride and the amine is octadecylamine or
N-methyl-N-octadecylamine.
46. The composition of claim 45 wherein the anionic polyelectrolyte
includes from about 5 mole percent to about 10 mole percent
octadecylamide or N-methyl-N-octadecylamide units.
47. The composition of claim 38 wherein the anionic polyelectrolyte
is made from a copolymer of an olefin and an unsaturated organic
anhydride, wherein said olefin contains from about 8 to about 36
carbon atoms.
48. The composition of claim 44 wherein the olefin is octadecene
and the unsaturated organic anhydride is maleic acid.
49. The composition of claim 41 further including an alkali metal
halide salt.
50. The composition of claim 49 wherein the alkali compound is
sodium hydroxide and the alkali metal salt is sodium chloride.
51. The composition of claim 41 further including a non-substantive
softener.
52. The composition of claim 51 wherein the non-substantive
softener is selected from the group consisting of fatty alcohol,
fatty acid ester, fatty alcohol ester, alkoxylated fatty alcohol,
esters of polyethylene glycol and/or polypropylene glycol with
fatty acids, Guerbet alcohols and mixtures thereof.
53. The composition of claim 52 wherein the alkoxylated fatty
alcohol is an ethoxylated, propoxylated, or ethoxylated and
propoxylated fatty alcohol and the fatty acid ester is a sorbitan
fatty acid ester or a fatty acid ester of polyethylene glycol
and/or polypropylene glycol.
54. A composition for enhancing the wet strength of a cellulosic
paper which comprises: a) anionic polyelectrolyte possessing
hydrophobic groups and anionic sites capable of bonding to unbound
cationic sites in a cationic wet strength resin; b) an aqueous
solution of an alkali compound and alkali halide salt; and c) a
Guerbet alcohol.
55. The composition of claim 54 wherein the anionic polyelectrolyte
is made by reacting a polymeric compound having anhydride groups
with an amine having the formula: HNR.sup.1R.sup.2 wherein R.sup.1
and R.sup.2 are each selected from the group consisting of hydrogen
and a saturated or unsaturated, straight chain or branched
aliphatic group having from 1 to 36 carbon atoms, with the proviso
that at least one of R.sup.1 and R.sup.2 is a hydrophobic saturated
or unsaturated, straight chain or branched aliphatic group having
from about 8 to about 36 carbon atoms.
56. The composition of claim 54 wherein the anionic polyelectrolyte
is made from a copolymer of an olefin and an unsaturated organic
anhydride, wherein said olefin contains from about 8 to about 36
carbon atoms.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present disclosure relates generally to the field of
making disposable paper products and, more specifically, to the
enhancement of the softness and wet strength characteristics of
paper tissue and towels.
[0003] 2. Description of Related Art
[0004] It is often desirable to increase the wet strength of paper
products. For example, paper towels are typically used to wipe up
wet spills and need sufficient strength when wet to prevent
disintegration in use. Typically, wet strength is evaluated in
relation to dry strength. A wet strength paper grade has a wet
strength of at least about 10% to 15% of its dry strength.
[0005] The wet strength of a paper can be enhanced by treating the
paper pulp slurry, or "furnish", with a reactive polymeric material
such as polyamidoamine-epichilorohydrin ("PAE"),
melamine-formaldehyde ("MF") or urea-formaldehyde ("UF")
resins.
[0006] PAE is commonly used. However, it has been found that
certain additives, when used in conjunction with PAE, enhance the
wet strength of the paper even further. For example, U.S. Pat. No.
3,058,873 discloses the use of a water soluble gum such as
carboxymetlhylcellulose ("CMC") to enhance the wet strength
efficiency of PAE. Although CMC is effective it suffers from
disadvantages. In particular, CMC requires the installation of
expensive equipment, and undissolved CMC can form deposits which
interfere with the operation of the paper making machinery.
[0007] U.S. Pat. No. 6,222.006, which is herein incorporated by
reference, discloses an aqueous formulation of a high solids
content wet strength resin which is the product of a reaction
between an epihalohydrin and an end-capped polyaminamide
polymer.
[0008] Another consideration which arises with paper for use as
facial tissue, table napkins, paper towels, is that of softness.
The tactile feeling of softness can be enhanced by decreasing dry
strength and/or increasing the lubricity of the paper. This can be
done by, for example, introducing hydrophobic groups into the paper
as part of cationic or anionic surface active agents. However,
surfactant molecules are relatively small and do not easily remain
on the surface of the paper fibers because they are poorly retained
and have a tendency to migrate into the fiber walls, thereby losing
effectiveness. Also, surfactants can reduce wet strength as well as
dry strength.
[0009] What is needed is an improved method for increasing the wet
strength of paper, while giving the paper a more cloth-like-feel,
or softness.
BRIEF SUMMARY OF THE INVENTION
[0010] A method is provided herein for making a cellulosic-paper to
enhance its wet strength and softness. The method comprises:
[0011] a) providing a pulp furnish containing at least one
cellulosic component possessing anionic sites;
[0012] b) adding separately to the pulp furnish to form a treated
pulp,
[0013] i. cationic wet strength resin possessing cationic sites
which bond to anionic sites on the cellulosic component of the pulp
furnish, there being present cationic wet strength resin possessing
unbound cationic sites, and
[0014] ii. anionic polyelectrolyte possessing anionic sites and
hydrophobic groups, with anionic sites of the anionic
polyelectrolyte bonding to unbound cationic sites of the wet
strength resin;
[0015] c) forming the treated pulp into a sheet; and,
[0016] d) drying the sheet.
[0017] Preferably, the cationic wet strength resin has azetidinium
or epoxide functionality.
[0018] Preferably, the anionic polyelectrolyte is made by reacting
a polymeric compound having anhydride groups with an amine having
the formula: HNR.sup.1R.sup.2
[0019] wherein R.sup.1 and R.sup.2 are each selected from the group
consisting of hydrogen and a saturated or unsaturated, straight or
branched aliphatic group having from 1 to 36 carbon atoms, with the
proviso that at least one of R.sup.1 and R.sup.2 is a hydrophobic
saturated or unsaturated, straight chain or branched aliphatic
group having from about 8 to about 36 carbon atoms.
[0020] The method advantageously increases the wet strength and the
wet/dry tensile strength ratio while using less additive. Also, the
hydrophobically modified anionic polyelectrolyte disclosed herein
provides a liquid substitute for CMC as well as being a molecular
carrier for non-ionic softeners such as Guerbet alcohols.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The present invention employs a hydrophobically modified
anionic polyelectrolyte ("HMAP") as a wet strength enhancement
additive in conjunction with a wet strength resin agent to provide
increased wet strength and a high wet/dry tensile strength ratio.
The term "polyelectrolyte" refers to water soluble molecules having
many repeating units, some or all of which have charged
functions.
[0022] The wet strength resin agent can be any cationic resin which
can form a covalent or ionic bond with cellulose fibers. Preferred
cationic wet strength resins include those having azetidinium or
epoxide functionality. Such resins include
polyamidoamine-epichlorohydrin (PAE) resin,
poly(diallylamine)-epichlorohydrin resin, polyalkylene
polyamine-epichlorohydrin resin (PAPAE). Quaternary ammonium
epoxide resins are also useful. Other cationic wet strength resins
include melamine-formaldehyde resins and urea-formaldehyde
resin.
[0023] A particularly suitable wet strength agent is PAE, which
contains cationic sites which form ionic bonds with the carboxyl
sites on the cellulosic pulp fibers. PAE suitable for use as a wet
strength agent is commercially available from various suppliers. A
PAE wet strength agent suitable for use in the present invention is
commercially available under the designation AMRES LA-12 from
Georgia-Pacific Corp. of Atlanta, Ga.
[0024] The amount of wet strength agent used preferably ranges from
about 1 pound per metric ton to 30 pounds per metric ton of dry
fiber, more preferably from about 10 pounds per metric ton to about
20 pounds per metric ton.
[0025] The preferred amount of wet strength agent depends upon the
demand for a given furnish. In practice, one first determines the
wet strength resin demand of a furnish (i.e., the amount of wet
strength resin needed to bond to the anionic sites of the
cellulosic component of a pulp furnish), and then determines the
excess amount of wet strength resin needed to achieve the desired
wet strength. Being anionic, the HMAP molecules of the present
invention attach to the excess cationic sites of the wet strength
resin.
[0026] The papermaking fibers useful in the present invention
include both bleached and unbleached hardwood fibers, bleached or
unbleached softwood fibers, bleached or unbleached recycled fibers,
synthetic fibers, non-woody fibers, and blends of the
aforementioned fiber types. For paper towels, particularly
suitable-fibers include bleached softwood kraft, and bleached
softwood chemithermomechanical pulp ("BCTMP").
[0027] In one embodiment, the HMAP compound of the present
invention is made by reacting a polymer containing anhydride groups
with a primary or secondary amine having the formula:
HNR.sup.1R.sup.2
[0028] wherein R.sup.1 and R.sup.2 are each selected from the group
consisting of hydrogen and a saturated or unsaturated, straight
chain or branched aliphatic group having from 1 to 36 carbon atoms,
with the proviso that at least one of R.sup.1 and R.sup.2 is a
hydrophobic saturated or unsaturated, straight chain or branched
aliphatic group having from about 8 to about 36 carbon atoms,
preferably from about 12 to 24 carbon atoms. Suitable preferred
primary and secondary amines include for example, octylamine,
decylamine, dodecylamine, tridecylamine, tetradecylamine,
pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine,
nonadecylamine, eicosylamine, N-methyl-N-octylamine,
N-methyl-N-decylamine, N-methyl-N-dodecylamine,
N-methyl-N-tridecylamine, N-methyl-N-tetradecylanime,
N-methyl-N-pentadecylamine, N-methyl-N-hexadecylamine,
N-methyl-N-heptadecylamine, N-methyl-N-octadecylamine,
N-methyl-N-nonadecylamine and N-methyl-N-eicosylamine,
N-ethyl-N-octylamine, N-ethyl-N-decylamine, N-ethyl-N-dodecylamine,
N-ethyl-N-tridecylamine, -ethyl-N-tetradecylamine,
N-ethyl-N-pentadecylamine, N-ethyl-N-hexadecylamine,
N-ethyl-N-heptadecylamine, N-ethyl-N-octadecylamine,
N-ethyl-N-nonadecylamine and N-ethyl-N-eicosylamine and mixtures
thereof.
[0029] The anhydride-containing polymer can be any addition type
polymer having anhydride groups, for example, a copolymer of a
polyolefin such as polyethylene, polypropylene, polystyrene with an
unsaturated organic anhydride such as maleic anhydride.
[0030] The resulting HMAP compound includes amide-containing units
which have --C(O)NR.sup.1R.sup.2 amide groups and --COOH groups.
Preferably, the HMAP includes from about 1 mole percent to about 30
mole percent amide-containing units, more preferably from about 5
mole percent to about 10 mole percent amide-containing units. The
--COOH groups preferably are neutralized by reaction with an alkali
metal hydroxide such as NaOH, KOH, etc. The resulting material can
form as a superabsorbent gel which can be treated with an alkali
metal halide (e.g., NaCl, KCl) to provide a viscous fluid.
[0031] In another embodiment, the HMA can be made from a copolymer
containing fatty groups (e.g., C.sub.8 to C.sub.36 straight or
branched chain aliphatic groups) and anhydride functionality. Such
a polymer can be made by copolymerizing a C.sub.8 to C.sub.36
olefin. (e.g., octene, decene, dodecene, tridecene, tetradecene,
pentadecene, hexadecene, heptadecene, octadecene, nonadecene,
eicosene, etc.) with an unsaturated anhydride (e.g., maleic
anhydride). A preferred copolymer is octadecene-maleic anhydride
copolymer, which is commercially available from Sigma-Aldrich
Chemical Co. of Milwaukee Wis. The HMAP is preferably made by
reacting the copolymer with an alkali (e.g., NaOH, KOH) in an
aqueous solution so as to form anionic sites on the polymer
chain.
[0032] Preparation of a wet strength paper product can be achieved
by adding a wet strength agent (e.g., PAE) to the paper pulp
furnish under suitable reaction conditions. By way of illustration,
reaction conditions can include ambient temperature, a pH of from
about 7.3 to about 7.5, and a reaction time of 1 to 10 minutes, for
example). Typically, the wet strength agent is added as an, aqueous
solution of from about 3% to about 1% or less.
[0033] The HMAP can be added to the furnish either before or after
the cationic wet strength resin. The pulp is then formed into
sheets which are then dried by conventional means. Optionally, the
sheets can be heat cured, for example, in a forced air oven.
[0034] Advantageously, the HMAP of the present invention further
enhances the retention of non-substantive softeners which are
non-ionic and do not form chemical linkages to cellulose fibers.
The HMAP serves as a molecular carrier to facilitate retention of
the non-substantive softeners by the cellulose fibers.
Non-substantive softeners include, for example, fatty alcohols and
their esters, fatty acid esters such as sorbitan fatty acid esters,
alkoxylated fatty alcohols, e.g., those obtained from the reaction
of a fatty alcohol with ethylene oxide, propylene oxide, etc., or
mixtures thereof, esters of polyethylene glycols and/or
polypropylene glycols with fatty acids, Guerbet alcohols, and
mixtures thereof. The aforementioned fatty alcohols can possess one
or two terminal hydroxyl groups, e.g., lauryl alcohol, palmityl
alcohol, stearyl alcohol, dimer fatty alcohols, and the like, and
the fatty acid moiety of the aforementioned fatty acid esters can
be derived from fatty acid moieties containing one or two
carboxylic acid groups, e.g., lauric acid, palmitic acid, stearic
acid, dimer fatty acids, and the like.
[0035] Guerbet alcohols ("Guerbalhols") are produced by the
catalytic condensation of a lower alcohol ("the Guerbet reaction")
to produce a higher molecular weight branched alcohol. The Guerbet
alcohols typically have the formula
R.sup.3CH.sub.2CH.sub.2CHR.sup.3CH.sub.2OH wherein R.sup.3 is an
aliphatic group containing at least 8 carbon atoms. Preferred
Guerbet alcohol molecules contain from about 20 to about 60 carbon
atoms. In particular, a preferred Guerbet alcohol composition is
available under the designation Guerbahol HMW, a mixture of 50%
C.sub.20 Guerbet alcohols, 25% C.sub.40 Guerbet alcohols and 25%
C.sub.60 Guerbet alcohols, available from Colonial Chemical Inc. of
South Pittsburg, Tenn.
[0036] It has been found that Guerbet alcohols can serve as
softeners for paper tissue and towels and increases the wet/dry
ratio percentage. The Guerbet alcohol is added to the pulp furnish
and preferably combined with the HMAP of the invention as an
emulsion.
[0037] Features of the invention are illustrated by the following
Examples.
EXAMPLE 1
[0038] British handsheets were prepared to a target basis weight of
about 55 g/m.sup.2 using an unrefined furnish of 1:1 bleached
hardwood and softwood Kraft pulps. A number of tests were preformed
in which tests designated as D-1 and D-2 were in accordance with
the present invention and the remaining tests were for comparison
purposes. The test results are set forth in table below. In each
test, to prepare the handsheets 10 g of fibers at 3% consistency
were treated for 5 minutes with a selected dosage of AMRES LA-12
PAE wet strength (W.S.) resin as a 1% aqueous-solution. In tests
A-1, A-2, C-1, C-2, D-1, D-2, and E-1, E-2, the dosage of Amres
LA-12 was 20 pounds per metric ton (lbs/ton). In tests B-1, B-2,
B-3, the dosage of Amres LA-12 was 8 lbs/ton.
[0039] The mixture was then diluted with 10 liters of tap water and
the pH was adjusted to 7.5.+-.0.2. Then, either CMC, HMAP, a
non-hydrophobically modified anionic polyelectrolyte ("AP"), or
nothing further, was added. In tests A-1, A-2, and B-1, B-2 no
further additive was used. In tests C-1 and C-2, CMC was added at a
dosage of 4 lbs/ton. In tests D-1 and D-2 the HMAP of the present
invention was employed at a dosage of 1.6 lbs/ton. In tests E-1 and
E-2, a non-hydrophobically modified anionic polyelectrolyte ("AP")
was used, also at a dosage of 1.6 lbs/ton.
[0040] HMAP was prepared by treating 2.4197 g (0.0165 mol) of
polyethylene-co-maleic anhydride with 0.4149 g (0.0015 mol)
N-methyl-N-octadecylamine in refluxing acetone overnight,
evaporating the acetone in vacuo, and redissolving in 200 mL of a
solution of 0.0564 g of NaOH in deionized water to yield a
superabsorbent gel. The latter was 1.58% solids. An 112.87 g
aliquot of the gel was treated with 4.58 g of a saturated aqueous
solution of sodium chloride to provide a highly viscous fluid. The
pH of the fluid was 10.
[0041] The non-hydrophobically modified AP was prepared by treating
21439 g (0.0170 mol) of polyethylene-co-maleic anhydride with about
0.08 g (0.0014 mol) N-ethyl-N-methylamine in stirring acetone in a
sealed flask at room temperature for two days, evaporating acetone
in vacuo, and redissolving in a solution prepared by mixing 17 mL
1.0 N NaOH and 50 mL deionized water to yield a viscous fluid at pH
6.4. A few drops of 10 N NaOH was added to bring pH to 7.5 and
provide a clear colorless fluid having a solids content of
4.473%.
[0042] Sheets were formed at pH 7.5, pressed between blotters, but
without plates, at 15 psi for 5 minutes, then dried on a rotating
dryer drum, cured at 105.degree. C. for 5 minutes in a forced air
oven, and tested for the properties set forth in the table
below.
[0043] Charge density was determined by titration using a Mutek
PCD-02 streaming current detector and standardized DADMAC or PVSK
reagents.
[0044] Dry tensile and wet tensile strengths were determined by
standard testing of 3'' strips in an Instron type tester.
[0045] Breaking length ("B.L.") is a-measure of tensile strength
and denotes the length of paper strip which would be self
supporting if held vertically.
[0046] As can be seen from the data in the table below, the HMAP of
the invention performed comparably with CMC. However, the dosage of
HMAP was only 1.6 lbs/ton as compared with 4 lbs/ton of the CMC.
That is, when using the HMAP wet strength enhancement additive of
the present invention, a reduction of 60% by wveight of dosage can
be achieved. The average wet tensile strength produced by the HMAP
of the invention (i.e., 1123 grams/1'') is superior to the test
results achieved by using wet strength agent Amres LA-12 alone
(i.e., 934 grams/1'' for tests A-1,2, and 777 grams/1'' for tests
B-1,2,3). Moreover, the average wet breaking length achieved by the
HMAP of the invention (i.e., 0.81) is also superior to the wet
breaking length achieved by wet strength agent Amres LA-12 alone
(i.e., 0.66-average for tests A-1,2 and 0.55 average for tests
B-1,2,3).
[0047] The importance of the hydrophobic component of the HMAP is
illustrated by the fact that the average wet B.L./dry B.L. for the
HMAP of the invention was 32% whereas the average wet B.L./dry B.L.
ratio for the non-hydrophobically modified AP was only 26.3%.
TABLE-US-00001 TABLE Properties of Handsheets Within, and Outside,
the Scope of the Invention Mutek Dry Wet Wet/Dry W.S. Resin CMC
HMAP.sup.(1) AP.sup.(2) Charge Basis Wt. Tensile Dry B.L. Tensile
Wet B.L. B.L. Handsheets lbs/ton lbs/ton lbs/ton lbs/ton (mL)
(g/m.sup.2) (g/1'') (km) (g/1'') (km) (%) A-1.sup.(3) 20 0 0 0
cationic 54.3 2801 2.12 964 0.69 32.4 A-2.sup.(3) 20 0 0 0 cationic
55.7 3173 2.24 903 0.64 28.5 Avg A-1, 2 -- -- -- -- cationic 55.0
2987 2.18 934 0.66 30.4 B-1.sup.(3) 8 0 0 0 -0.016 54.1 3401 2.48
798 0.58 23.4 B-2.sup.(3) 8 0 0 0 -0.022 55.7 2981 2.11 747 0.53
25.1 B-3.sup.(3) 8 0 0 0 -0.025 55.7 3337 2.33 786 0.55 23.5 Avg
B-1, 2, 3 -- -- -- -- -0.021 55.2 3240 2.30 777 0.55 24.0
C-1.sup.(3) 20 4 0 0 -0.030 55.9 3963 2.79 1226 0.86 30.9
C-2.sup.(3) 20 4 0 0 -0.018 54.7 3749 2.70 1292 0.93 34.5 Avg C-1,
2 -- -- -- -- -0.024 55.3 3856 2.75 1259 0.90 32.7 D-1.sup.(4) 20 0
1.6 0 -0.016 56.7 3672 2.55 1239 0.86 33.8 D-2.sup.(4) 20 0 1.6 0
-0.017 56.7 3326 2.52 1006 0.76 30.3 Avg D-1, 2 -- -- -- -- -0.017
56.7 3499 2.53 1123 0.81 32.0 E-1.sup.(3) 20 0 0 1.6 -0.066 52.9
4127 3.07 1047 0.78 25.4 E-2.sup.(3) 20 0 0 1.6 -0.048 56.1 4268
2.99 1161 0.81 27.2 Avg E-1, 2 -- -- -- -- -0.057 54.5 4198 3.03
1104 0.80 26.3 .sup.(1)Polyethylene-co-maleic anhydride having 7.8
mole percent N-methyl-N-octadecylamide (hydrophobic) units.
.sup.(2)Polyethylene-co-maleic anhydride having 7.8 mole percent
N-methyl-N-methylamide (non-hydrophobic) units. .sup.(3)Outside the
scope of the invention. .sup.(4)Within the scope of the
invention.
EXAMPLE 2
[0048] British handsheets were prepared in accordance with the
procedure set forth in Example I with a dosage of 20 lbs/ton Amres
LA-12, except that the HMAP employed was a polyethylene-co-maleic
anhydride polymer containing 7.8 mole percent octadecylamide units
made in accordance with the following procedure:
[0049] A flask was charged with 7.29 g (0.059 mol)
polyethylene-co-maleic anhydride, 1.22 g (0.0045 mmol)
octadecylamine and 100 mL acetone, and heated at reflex with
stirring over a two day period. The acetone was removed under
vacuum and the solids were dissolved in a stirred solution of 4.37
g sodium chloride and 4.62 (0.12 mol) sodium hydroxide in 863 mL
deionized water over a 24 hour period to yield a hazy viscous fluid
having an active polymer solids content of 1.3% by weight. A dosage
of 1.6 lbs/ton of the resulting HMAP was employed to prepare the
handsheets.
[0050] The handsheets were tested in accordance with the procedures
set forth in Example 1 and exhibited the following properties:
TABLE-US-00002 Mutek charge -0.023 mL Basis weight 54.9 g/m.sup.2
Dry tensile 3552 g/l'' Dry breaking length 2.6 km Wet tensile 1019
g/l'' Wet breaking length 0.74 km Wet/dry tensile % 29%
EXAMPLE 3
[0051] British handsheets were prepared in accordance with the
procedure set forth in Example 1 with a dosage of 20 lbs/ton Amres
LA-12, except that the HMAP employed was prepared from a
polyoctadecene-co-maleic anhydride polymer and alkali in accordance
with the following procedure.
[0052] A beaker was charged Keith 2.24 g (0.56 mol) sodium
hydroxide, 800 mL deionized water, and 10 g (0.0289 mol)
polyoctadecene-co-maleic anhydride. The polyoctadecene-co-maleic
anhydride was obtained from Sigma-Aldrich Chemical Co. under the
product number designation 41,911-7. The slurry was stirred over a
water bath at 70.degree. C. for 3 hours to provide a clear,
colorless solution having 1.496% by weight solids content. A dosage
of 3.9 lbs/ton of the resulting HMAP was used to prepare the
handsheets.
[0053] The handsheets were tested in accordance with the procedure
set forth in Example 1 and exhibited the following properties.
TABLE-US-00003 Mutek charge -0.051 mL Basis weight 56.5 g/m.sup.2
Dry tensile 3721 g/l'' Dry breaking length 2.6 km Wet tensile 1059
g/l'' Wet breaking length 0.74 km Wet/dry tensile % 29%
EXAMPLE 4
[0054] British handsheets were prepared in accordance with the
procedure set forth in Example I with a dosage of 20 lbs/ton Amres
LA-12 except as follows.
[0055] HMAP was prepared from polyethylene-co-maleic anhydride and
octadecylamine and combined with a Guerbet alcohol in accordance
with the following procedure.
[0056] A flask was charged with 7.29 g (0.058 mol)
polyethylene-co-maleic anhydride, 1.22 g (0.0045 mol)
octadecylamine, and 100 mL acetone and heated at reflux with
stirring overnight. The solution was transferred to a beaker and
allowed to thoroughly evaporate over a hot water bath. The solids
were then dispersed by stirring in a solution of 4.59 g (0.114 mol)
sodium hydroxide, 4.49 g sodium chloride, and 8.19 g Guerbahol HMW
in 863 mL deionized water over the weekend to yield a white
emulsion having a pH of 10 and an active polymer solids of
1.395%.
[0057] The HMAP and Guerbahol HMW were added to the pulp furnish as
a combined emulsion at respective dosages of 1.6 lbs/ton and 1
lb/ton to prepare the handsheets.
[0058] The handsheets were tested and exhibited the following
properties: TABLE-US-00004 Mutek charge -0.014 mL Basis weight 54.7
g/m.sup.2 Dry tensile 3656 g/l'' Dry breaking length 2.6 km Wet
tensile 1032 g/l'' Wet breaking length 0.74 km Wet/dry tensile %
28% Guerbahol retention % 56%
EXAMPLE 5
[0059] British handsheets were prepared in accordance with the
procedure set forth in Example I with a dosage of 25 lbs/ton Amres
LA-12 except as follows.
[0060] HMAP, prepared from polyoctadecene-co-maleic anhydride
reacted with alkali (sodium hydroxide), w as combined with
Guerbahol HMW in accordance with the following procedure.
[0061] A beaker was charged with 2.28 g (0.057 mol) sodium
hydroxide, 800 ml deionized water, 10 g (0.029 mol)
polyoctadecene-co-maleic anhydride, and 2.39 g Guerbahol HMW, and
stirred over a water bath at 70.degree. C. for 3 hours to provide a
white emulsion having an active polymer solids of 1.646%. The
polyoctadecene-co-maleic anhydride was obtained from Sigma-Aldrich
Chemical Co. under the product number designation 41,911-7.
[0062] The HMAP and Guerbahol HMW were added to the pulp furnish as
a combined emulsion at respective dosages of 5.6 lbs/ton and 1
lb/ton to prepare the handsheets.
[0063] The handsheets were tested and exhibited the following
properties: TABLE-US-00005 Mutek charge -0.016 mL Basis weight 55.7
g/m.sup.2 Dry tensile 2938 g/l'' Dry breaking length 2.1 km Wet
tensile 970 g/l'' Wet breaking length 0.68 km Wet/dry tensile % 33%
Guerbahol retention % 60%
COMPARATIVE EXAMPLE
[0064] This Comparative Example is outside the scope of the
invention.
[0065] British handsheets were prepared in accordance with the
procedure set forth in Example I with a dosage of 20 lbs/ton Amres
LA-12 except as follows.
[0066] An emulsion of Guerbahol HMW and PEG-600-monolaurate was
prepared as follows:
[0067] A beaker was charged with 13 g, Guerbahol HMW. A solution of
1.19 g Lumulse 60-L brand PEG-600-monolaurate in 15 mL deionized
water treated with a tiny amount of Dow Anti-foam was slowly added
to the Guerbahol HMW while stirring using a PowerGen 700 Emulsifier
fitted with a OMNI-Tip.RTM. Plastic Disposable Rotor Stator
Generator Probe at about 13000 rpm until a smooth white emulsion
was obtained (about 30 min) having a solids of 44.54%.
[0068] CMC was added to the pulp furnish at a dosage of 4 lbs/ton
and the Guerbahol HMW emulsion was added at a dosage of 1 lb/ton of
Guerbahol HMW to produce the hand sheets.
[0069] The handsheets were tested and exhibited the following
properties: TABLE-US-00006 Mutek charge -0.031 mL Basis weight 55.6
g/m.sup.2 Dry tensile 4219 g/l'' Dry breaking length 3.0 km Wet
tensile 1312 g/l'' Wet breaking length 0.93 km Wet/dry tensile %
31% Guerbahol retention % 38%
[0070] As can be seen from Examples 4 and 5, the Guerbet alcohol
retention achieved by the HMAP of the invention was significantly
higher (56% and 60%) than the Guerbet alcohol retention achieved by
CMC in the Comparative Example (38%).
[0071] While the above description contains many specifics, these
specifics should not be construed as limitations on the scope of
the invention, but merely as exemplifications of preferred
embodiments thereof. Those skilled in the art will envision many
other possible variations that are within the scope and spirit of
the invention as defined by the claims appended hereto.
* * * * *