U.S. patent application number 10/993731 was filed with the patent office on 2005-07-28 for paper making process and starch compositions comprising a crosslinking agent for use in same.
This patent application is currently assigned to Bercen Incorporated. Invention is credited to Capwell, David A..
Application Number | 20050161182 10/993731 |
Document ID | / |
Family ID | 34632849 |
Filed Date | 2005-07-28 |
United States Patent
Application |
20050161182 |
Kind Code |
A1 |
Capwell, David A. |
July 28, 2005 |
Paper making process and starch compositions comprising a
crosslinking agent for use in same
Abstract
The present invention relates to methods for manufacturing paper
or paperboard with improved strength and drainage by introduction
into the fiber furnish, prior to sheet formation, an aqueous starch
dispersion of a gelatinized, self-retaining starch, and an aldehyde
generating compound or a glyoxal releasing compound. The present
invention further relates to pre-gelatinized starch compositions
comprising an aqueous mixture of a pre-gelatinized starch and an
aldehyde generating compound or a glyoxal releasing compound.
Inventors: |
Capwell, David A.; (West
Greenwich, RI) |
Correspondence
Address: |
EDWARDS & ANGELL, LLP
P.O. BOX 55874
BOSTON
MA
02205
US
|
Assignee: |
Bercen Incorporated
|
Family ID: |
34632849 |
Appl. No.: |
10/993731 |
Filed: |
November 19, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60523947 |
Nov 21, 2003 |
|
|
|
Current U.S.
Class: |
162/158 ;
162/175 |
Current CPC
Class: |
C08L 3/02 20130101; C08L
3/08 20130101; C08K 5/3462 20130101; D21H 17/28 20130101; C08L 3/00
20130101; D21H 17/06 20130101; C08K 5/3462 20130101; D21H 21/18
20130101; C08L 3/02 20130101 |
Class at
Publication: |
162/158 ;
162/175 |
International
Class: |
D21H 017/72; D21H
017/28; D21H 017/06 |
Claims
What is claimed is:
1. A method for manufacturing paper or paperboard sheet with
increased strength, the method comprising the steps of: providing a
fiber slurry suitable for use in making paper or paperboard;
incorporating a gelatinized starch composition into the fiber
slurry, wherein the gelatinized starch composition comprises:
gelatinized starch; and an aldehyde generating compound capable of
forming at least two or more covalent bonds to functional groups
present in the starch or fiber when the aldehyde generating
compound is heated above an activation temperature; forming the
paper or paperboard sheet; heating the paper or paperboard sheet at
a temperature above the activation temperature of the aldehyde
generating compound which is sufficient to dry the paper or
paperboard sheet.
2. The method of claim 1, wherein a paper sheet is prepared by the
method of manufacture.
3. The method of claim 1, wherein a paperboard sheet is prepared by
the method of manufacture.
4. The method of claim 1, wherein the starch is self-retaining.
5. The method of claim 4, wherein the starch is a net cationic
starch.
6. The method of claim 4, wherein the starch is pregelatinized
self-retaining starch selected from potato, corn or wheat
starch.
7. The method of claim 1, wherein the gelatinized starch
composition comprises between 0.5% to 50% aldehyde generating
compound based on the dry weight of the starch and aldehyde
generating compound.
8. The method of claim 1, wherein the aldehyde generating compound
reacts with starch or gelatinized starch with a rate sufficiently
slow to permit storage of the composition for at least one day at
room temperature.
9. The method of claim 8, wherein the aldehyde generating compound
reacts with starch or gelatinized starch at a sufficiently slow
rate to permit storage of the composition for at least one week at
room temperature.
10. The method of claim 8, wherein the aldehyde generating compound
reacts with starch or gelatinized starch at a sufficiently slow
rate to permit storage of the composition for at least three weeks
at room temperature.
11. The method of claim 1, wherein the gelatinized starch
composition further comprises at least one aldehyde blocking
compound capable of blocking aldehyde residues.
12. The method of claim 11, wherein the aldehyde blocking compound
loading is at least 10 molar % of the aldehyde generating
compound.
13. The method of claim 11, wherein the aldehyde blocking compound
is selected from the group consisting of C.sub.1-20alcohols,
C.sub.2-20alkylene glycols, and C.sub.1-20alkylamines.
14. The method of claim 11, wherein the aldehyde blocking compound
is selected from the group consisting of methanol, ethanol,
propanol, ethylene glycol, glycerin, propylene glycol and urea.
15. The method of claim 1, wherein the aldehyde generating compound
is a glyoxal releasing compound.
16. The method of claim 15, wherein the glyoxal releasing compound
is a reaction product of at least one molar equivalent of glyoxal
with between about 0.25 and about 5 molar equivalents of one or
more stabilizing agents.
17. The method of claim 16, wherein the glyoxal releasing compound
thermally degrades at the temperature sufficient to dry paper or
paperboard thereby releasing one or more equivalents of
glyoxal.
18. The method of claim 17, wherein the thermally released glyoxal
forms crosslinks between two starch moieties or between a starch
moiety and fiber by reacting with functional groups of the starch
moiety or fiber to form covalent bonds.
19. The method of claim 16, wherein the glyoxal releasing compound
is a reaction product of at least one molar equivalent of glyoxal;
and between about 0.5 and about 5 molar equivalents of stabilizing
agents selected from the group consisting of optionally substituted
urea, optionally substituted thiourea, optionally substituted
imidazolidin-2-one, and optionally substituted
tetrahydro-pyrimidin-2-one.
20. The method of claim 11, wherein the aldehyde generating
compound is a reaction product of at least one molar equivalent of
glyoxal; and between about 1 and about 3 molar equivalent of
stabilizing agents selected from the group consisting of urea,
thiourea, 4,5-dihydroxy-imidazolidin-2-one, and
4-hydroxy-5-(C.sub.1-10-alkyl)-tetrahydro-pyrimidin-2-one.
21. The method of claim 19, wherein the glyoxal releasing compound
is a compound according to Formula I: 10wherein A is an optionally
substituted methylene group, an optionally substituted
C.sub.2-4alkylene group, or a single bond; B is carbonyl,
thiocarbonyl, or an optionally substituted 1,2-ethylene residue;
X.sub.1 and X.sub.2 are independently selected from the group
consisting of oxygen and NR.sub.3; R.sub.1 and R.sub.2 are
independently selected from the group consisting of hydrogen,
hydroxyl, optionally substituted C.sub.1-20alkyl, optionally
substituted C.sub.1-20alkoxy, optionally substituted urea,
optionally substituted thiourea, or R.sub.1 and R.sub.2, taken in
combination, form a N,N'-divalent urea; R.sub.3 is independently
selected at each occurrence of R.sub.3 from the group consisting of
hydrogen, optionally substituted C.sub.1-20alkyl, and blocked
glyoxal residues, where the blocked glyoxal residue is a
1-hydroxy-2-(protected aldehyde residue)-ethan-1-yl group; and
wherein the aldehyde generating compound according to Formula I
thermally degrades to generate at least one equivalent of glyoxal
when heated above an activation temperature.
22. The method of claim 21, wherein the aldehyde generating
compound is a glyoxal releasing compound.
23. The method of claim 22, wherein R.sub.1 and R.sub.2 are
independently selected from the group consisting of hydrogen,
hydroxyl, methanol, ethanol, urea, or R.sub.1 and R.sub.2, taken in
combination, form a N,N'-divalent urea; R.sub.3 is independently
selected at each occurrence of R.sub.3 from the group consisting of
hydrogen, methyl, and ethyl, or R.sub.3 is a blocked glyoxal
residue selected from the group consisting of
1,2-dihydroxy-2-(C.sub.1-4-alkoxy)-ethan-1-yl,
1,2-dihydroxy-2-(3-hydr- oxypropoxy)-ethan-1-yl, and
1,2-dihydroxy-2-(2-hydroxypropoxy)-ethan-1-yl.
24. The method of claim 22, wherein X.sub.1 and X.sub.2 are
NR.sub.3; A is a single bond; B is a carbonyl or thiocarbonyl
group; and R.sub.1 and R.sub.2 are independently selected from
hydroxyl, C.sub.1-6-alkoxy, or blocked glyoxal residues.
25. The method of claim 22, wherein X.sub.1 and X.sub.2 are
NR.sub.3; A is a 1,1-C.sub.1-6alkylene group; B is a carbonyl or
thiocarbonyl group; R.sub.1 and R.sub.2 are independently selected
from hydrogen, hydroxyl, C.sub.1-6-alkoxy, or blocked glyoxal
residues; and R.sub.3 is a blocked glyoxal residue selected from
the group consisting of
1,2-dihydroxy-2-(C.sub.1-4-alkoxy)-ethan-1-yl,
1,2-dihydroxy-2-(3-hydroxy- propoxy)-ethan-1-yl, and
1,2-dihydroxy-2-(2-hydroxypropoxy)-ethan-1-yl.
26. The method of claim 22, wherein the glyoxal releasing compound
comprises at least one compound selected from the group consisting
of compounds of the formulae: 11
27. The method of claim 1, wherein the gelatinized starch
composition further comprises a cationic starch containing at least
one ammonium salt.
28. A gelatinized starch composition for use strengthening paper or
paperboard, the composition comprising: a self-retaining
gelatinized starch; at least one aldehyde blocking compound capable
of blocking aldehyde residues; and an aldehyde generating compound
according to the Formula I: 12wherein A is an optionally
substituted methylene group, an optionally substituted
C.sub.2-4alkylene group, or a single bond; B is carbonyl,
thiocarbonyl, or an optionally substituted 1,2-ethylene residue;
X.sub.1 and X.sub.2 are independently selected from the group
consisting of oxygen and. NR.sub.3; R.sub.1 and R.sub.2 are
independently selected from the group consisting of hydrogen,
hydroxyl, optionally substituted C.sub.1-20alkyl, optionally
substituted C.sub.1-20alkoxy, optionally substituted urea,
optionally substituted thiourea, or R.sub.1 and R.sub.2, taken in
combination, form a N,N'-divalent urea; R.sub.3 is independently
selected at each occurrence of R.sub.3 from the group consisting of
hydrogen, optionally substituted C.sub.1-20alkyl, and blocked
glyoxal residues, where the blocked glyoxal residue is a
1-hydroxy-2-(protected aldehyde residue)-ethan-1-yl group; wherein
the aldehyde generating compound according to Formula I thermally
degrades to generate at least one equivalent of aldehyde when
heated above an activation temperature; and wherein the aldehyde
blocking compound loading is at least 10 molar % of the aldehyde
generating compound.
29. The gelatinized starch composition of claim 28, wherein the
aldehyde generating compound is a glyoxal releasing compound.
30. The gelatinized starch composition of claim 29, wherein the
glyoxal releasing compound reacts with starch or gelatinized starch
with a rate sufficiently slow to permit storage of the composition
for at least one day at room temperature.
31. The gelatinized starch composition of claim 29, wherein the
glyoxal releasing compound reacts with starch or gelatinized starch
at a sufficiently slow rate to permit storage of the composition
for at least one week at room temperature.
32. The gelatinized starch composition of claim 29, wherein the
glyoxal releasing compound reacts with starch or gelatinized starch
at a sufficiently slow rate to permit storage of the composition
for at least three weeks at room temperature.
33. The gelatinized starch composition of claim 29, wherein the
glyoxal releasing compound is capable of forming at least two or
more covalent bonds to functional groups present in the starch or
fiber when the glyoxal releasing compound is heated above an
activation temperature.
34. The gelatinized starch composition of claim 29, wherein the
starch is a cationic starch.
35. The gelatinized starch composition of claim 29, wherein the
starch is selected from potato, corn or wheat starch.
36. The gelatinized starch composition of claim 29, wherein the
aldehyde blocking compound is selected from the group consisting of
C.sub.1-20alcohols, C.sub.2-20alkylene glycols, and
C.sub.1-20alkylamines.
37. The gelatinized starch composition of claim 29, wherein the
aldehyde blocking compound is selected from the group consisting of
methanol, ethanol, propanol, ethylene glycol, and propylene
glycol.
38. The gelatinized starch composition of claim 29, wherein R.sub.1
and R.sub.2 are independently selected from the group consisting of
hydrogen, hydroxyl, methanol, ethanol, urea, or R.sub.1 and
R.sub.2, taken in combination, form a N,N'-divalent urea; R.sub.3
is independently selected at each occurrence of R.sub.3 from the
group consisting of hydrogen, methyl, and ethyl, or R.sub.3 is a
blocked glyoxal residue selected from the group consisting of
1,2-dihydroxy-2-(C.sub.1-4-alkoxy)-ethan-1-yl,
1,2-dihydroxy-2-(3-hydroxypropoxy)-ethan-1-yl, and
1,2-dihydroxy-2-(2-hydroxypropoxy)-ethan-1-yl.
39. The gelatinized starch composition of claim 29, wherein X.sub.1
and X.sub.2 are NR.sub.3; A is a single bond; B is a carbonyl or
thiocarbonyl group; and R.sub.1 and R.sub.2 are independently
selected from hydroxyl, C.sub.1-6alkoxy, or stabilized glyoxal
residues.
40. The gelatinized starch composition of claim 29, wherein X.sub.1
and X.sub.2 are NR.sub.3; A is a 1,1-C.sub.1-6alkylene group; B is
a carbonyl or thiocarbonyl group; R.sub.1 and R.sub.2 are
independently selected from hydrogen, hydroxyl, C.sub.1-6alkoxy, or
stabilized glyoxal residues; and R.sub.3 is a blocked glyoxal
residue selected from the group consisting of
1,2-dihydroxy-2-(C.sub.1-4-alkoxy)-ethan-1-yl,
1,2-dihydroxy-2-(3-hydroxypropoxy)-ethan-1-yl, and
1,2-dihydroxy-2-(2-hydroxypropoxy)-ethan-1-yl.
41. The gelatinized starch composition of claim 29, wherein the
glyoxal releasing compound comprises at least one compound selected
from the group consisting of is compounds of the formulae: 13
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention provides methods of manufacturing
paper and paperboard materials having increased strength, and more
particularly provides a method of making paper and paperboard
materials possessing increased wet and dry strength. The present
invention further provides starch compositions suitable for use in
the methods of making paper or paperboard materials with increased
strength provided by the invention. The compositions comprise at
least one type of gelatinized starch and at least one aldehyde
generating compound, or more preferably a glyoxal releasing
compound, which typically is activated during the drying process of
the paper making process.
[0003] 2. Background
[0004] Industrial starch may be utilized in a wide variety of paper
making applications, such as a coating binder or surface treatment
for paper and paperboard materials, and as a strength and retention
wet end additive in papermaking. Starch compositions are frequently
prepared as an aqueous dispersion which is capable of being added
to the pulp slurry. For many commercial applications starch is
gelatinized prior to addition of the starch to the pulp slurry, and
may be carried out by the starch provider or the paper
manufacturer. Gelatinization typically occurs after starch granules
are dispersed as a slurry in water and the resultant aqueous slurry
is heated to a temperature of 50.degree. C. or more, and more
typically to a temperature of 95.degree. C. or more. In certain
gelatinization methods, the starch granules are heated to a
temperature of more than 100.degree. C., such as starch gelatinized
using a commercial jet cooker or another pressurized steam cooker.
Under such conditions starch grains tend to absorb water, swell and
eventually rupture to allow starch fragments and molecules to
disperse in the water. This process of rupturing and dispersion is
generally referred to as "gelatinization" and is an irreversible
reaction, resulting in a relatively thick starch dispersion.
[0005] The crosslinking of starch with multi-functional reagents,
which are reactive with starch hydroxyl groups, is well known.
Glyoxal and polyaldehyde compounds and resins have been previously
utilized as crosslinkers. Simple mixing of glyoxal with a starch
dispersion rapidly affords a gel. However, glyoxal is infinitely
soluble in water and does not interact efficiently with other
chemicals or compositions, particularly heterogeneous materials
dispersed in small quantities in large volumes of water, e.g., such
as gelatinized starch molecules or cellulosic fibers present in the
wet-end of the paper making process. Thus, addition of glyoxal or
other low molecular weight crosslinkers directly to the wet-end of
the papermaking process has not been found to provide benefit to
end product of the paper making process.
[0006] U.S. Pat. No. 6,303,000 issued to Floyd et al. (Floyd '000)
discloses gelatinized starch compositions crosslinked with a
glyoxal resin and the use of same in paper making. The crosslinked
starch composition of Floyd '000 comprise the reaction product
formed by heating starch with a blocked glyoxal resin such as those
resins recited in U.S. Pat. No. 4,695,606 (Floyd, '606) during the
gelatinization process. The heating process forms a gelatinized
starch that is crosslinked by the glyoxal resin. More particularly,
Floyd '000 discloses the addition of a crosslinked gelatinized
starch composition to the wet end of the paper making process. In
other words, prior to addition to the wet end, the starch is heated
with the blocked glyoxal resin to gelatinize the starch and induce
a crosslinking reaction between the glyoxal and the starch. The
Floyd '000 patent further discloses that the glyoxal resin can be
pre-mixed with the starch prior to the gelatinization heating step
or added during the starch gelatinization process. Floyd suggests
that pre-mixing the starch and blocked glyoxal resin prior to the
gelation process or addition of the blocked glyoxal resin during
the gelatinization process, affords superior material having
improved shelf stability.
[0007] The Floyd '606 patent describes paper binder compositions
comprising a mixture of an acrylic or vinyl polymer with a blocked
glyoxal resins, e.g., such as the reaction product of glyoxal and a
urea or a cyclic urea. More particularly, the blocked glyoxal resin
is a condensation polymer of glyoxal blocked with urea, cyclic
ureas such as ethylene urea, 4,5-dihydroxyethylene urea and
propylene urea, carbamates, glycols, or polyols.
[0008] In Floyd '000 the addition levels of the gelatinized starch
composition demonstrated to affect a significant improvement in
paper or paperboard strength are relatively high at the level of 40
lb or more dry starch composition per ton of dry pulp. It is well
known in the art of papermaking that significant issues may occur
when relatively high levels of starch are used to produce paper,
including high cost, high levels of effluent Biological Oxygen
Demand (BOD), reduction in paper opacity, machine deposits, and
problems with dewatering and drying the paper or paperboard leading
to reduced production rates. It would thus be desirable to have
paper strength compositions that are effective at lower levels of
usage.
[0009] As an alternative approach, it would be desirable to have a
starch composition including a stabilized aldehyde generating
compound or a stabilized glyoxal compound that is activated upon
drying of the formed paper and paperboard materials. It would also
be desirable to provide methods of making paper and paperboard with
increased strength using such starch compositions.
SUMMARY OF THE INVENTION
[0010] The present invention provides storage stabile,
pre-gelatinized starch compositions that include at least one
glyoxal releasing compound or at least one aldehyde generating
compound. These compounds facilitate a process of manufacturing
paper or paperboard having improved strength using less
pre-gelatinized starch composition than previous paper or
paperboard manufacturing processes. Preferably, the manufacturing
processes of certain embodiments of the invention provide paper or
paperboard materials with equivalent strength and a reduced basis
weight when compared to paper or paperboard materials made with
previous paper manufacturing processes.
[0011] In accord with the present invention, a method for
manufacturing paper and paperboard materials with increased
strength, the method comprising the steps of:
[0012] providing a storage stabile, gelatinized starch composition
comprising gelatinized starch and at least one aldehyde generating
compound capable of forming at least two or more covalent bonds to
functional groups present in the starch or fiber when the aldehyde
generating compound is heated above an activation temperature;
[0013] providing a fiber slurry suitable for use in making paper or
paperboard;
[0014] incorporating a gelatinized starch composition into the
fiber slurry;
[0015] forming a paper or paperboard sheet; and
[0016] heating the paper or paperboard sheet at a temperature above
the activation temperature of the aldehyde generating compound and
which is sufficient to dry the paper or paperboard sheet.
[0017] The present invention also provides gelatinized starch
compositions which are suitable for strengthening paper prepared by
the methods of the invention where the starch composition comprises
a mixture of:
[0018] a self-retaining gelatinized starch;
[0019] at least one aldehyde blocking compound capable of blocking
aldehyde residues; and
[0020] an aldehyde generating compound according to the Formula I:
1
[0021] wherein
[0022] A is an optionally substituted methylene group, an
optionally substituted .alpha.,.omega.-C.sub.2-4-alkylene, or a
single bond;
[0023] B is carbonyl, thiocarbonyl, or an optionally substituted
1,2-ethylene residue;
[0024] X.sub.1 and X.sub.2 are independently selected from the
group consisting of oxygen and NR.sub.3;
[0025] R.sub.1 and R.sub.2 are independently selected from the
group consisting of hydrogen, hydroxyl, optionally substituted
C.sub.1-20alkyl, optionally substituted C.sub.1-20alkoxy,
optionally substituted urea, optionally substituted thiourea, or
R.sub.1 and R.sub.2, taken in combination, form a N,N'-divalent
urea;
[0026] R.sub.3 is independently selected at each occurrence of
R.sub.3 from the group consisting of hydrogen, optionally
substituted C.sub.1-20alkyl, a blocked dialdehyde compound (e.g., a
stabilized dialdehyde compound) comprising at least two protected
aldehyde residues, and a blocked glyoxal residue, where the blocked
glyoxal residue is a 1-hydroxy-2-(protected aldehyde
residue)-ethan-1-yl group;
[0027] wherein the aldehyde generating compound according to
Formula I thermally degrades to generate at least one equivalent of
glyoxal or a compound comprising two or more aldehyde residues when
heated above an activation temperature; and
[0028] wherein the aldehyde blocking compound loading is at least
10 molar % of the aldehyde generating compound.
[0029] Preferred aldehyde generating compounds according to Formula
I include glyoxal releasing compounds such as those compounds in
which (i) A is a single bond and R.sub.1 and R.sub.2 are hydroxyl,
or (ii) R.sub.3 contains a glyoxal residue that can generate
glyoxal, or compounds satisfying both conditions (i) and (ii).
[0030] Other aspects of the invention are discussed infra.
[0031] For purposes of the present invention, the term
"self-retaining starch" means any starch, that through its
functionality, has the property of being retained effectively in
the paper or paperboard web during the process of sheet
consolidation during the papermaking process. Though not limited to
the general description, this usually requires that the starch have
a net cationic charge for retention on the generally anionic fibers
used to make paper and paperboard.
[0032] Thus, a "self-retaining gelatinized starch" is added to the
papermaking slurry at some point before consolidation of the paper
web and is substantially retained or adsorbed onto the fiber
components of the slurry and becomes a component of the paper or
paperboard.
[0033] For the purposes of the present invention, the term
"aldehyde generating compound" refers to materials that upon
activation by heat will generate compounds containing two or more
reactive aldehyde residues that are then available for reaction
With functional groups that generally react in an aqueous
environment with aldehyde groups. Moreover, the term aldehyde
generating compound includes those compounds capable of generating
polyaldehyde compounds upon thermal degradation and compounds
capable of generating one or more aldehyde groups in sequence such
that two or more covalently connected aldehyde residues are
generated during the thermal degradation of the aldehyde generating
compound. Particularly preferred aldehyde generating compounds
release glyoxal or generate one or two aldehyde groups which are
derived from glyoxal.
[0034] For the purposes of the present invention, the term "glyoxal
releasing compound" refers to materials that upon activation by
heat will generate compounds containing reactive glyoxal moieties
that are then available for reaction with functional groups that
generally react in an aqueous environment with glyoxal. In general,
glyoxal releasing compounds are a subset of aldehyde generating
compounds.
[0035] For the purposes of the present invention, the term "blocked
aldehyde residue" refers to structures in which at least one
aldehyde group is hindered from forming free or active aldehyde
groups under storage or wet end paper making conditions. Similarly,
the term "blocked glyoxal residue," as used herein, refers to
structures in which the glyoxal releasing group is hindered from
forming a free or active aldehyde group under the current
conditions present.
[0036] For the purposes of the present invention, the term
"stabilizing agent" refers to any compound or combination of
compounds capable of forming a cyclic ring structure which
comprises one or more equivalents of glyoxal as a part of the ring
structure or as a substituent thereof. Preferred stabilizing agents
are capable of masking, blocking or otherwise protecting one, or
preferably, two aldehyde functional groups of glyoxal from
undergoing undesired reactions prior to the drying step of the
paper making process.
[0037] For the purposes of the present invention, the term
"aldehyde blocking agent" refers to any compound or combination of
compounds capable of masking, blocking or otherwise protecting an
aldehyde functional group and preferably are capable of masking or
blocking aldehyde functional groups in an aqueous environment.
Typically preferred aldehyde blocking agents release or unmask the
aldehyde group at elevated temperatures such as the temperature
used to dry paper or paperboard.
DETAILED DESCRIPTION OF THE INVENTION
[0038] Self-retaining gelatinized starch compositions of the
present invention comprise an aqueous dispersion containing at
least one self-retaining gelatinized starch and at least one
aldehyde generating compound or glyoxal releasing compound that are
suitable for imparting increased strength to paper. Preferred
aqueous self-retaining gelatinized starch compositions of the
invention comprise at least one glyoxal releasing compound
comprising at least one blocked glyoxal residue which is capable of
generating reactive aldehyde groups and/or releasing glyoxal upon
heating the glyoxal releasing compound. Typically preferred aqueous
self-retaining gelatinized starch compositions of the invention are
resistant to gelation and viscosity increase during storage,
particularly when stored at a temperature of 40.degree. C. or less.
Moreover, preferred gelatinized starch compositions of the
invention have a sufficiently low viscosity to permit the
composition to flow.
[0039] The self-retaining gelatinized starch compositions of the
present invention are particularly useful for manufacturing paper
or paperboard sheet having increased strength at the same basis
weight, or having the same strength with reduced basis weight. The
methods for manufacturing paper or paperboard typically comprise
providing a fiber slurry suitable for use in making paper;
incorporating a gelatinized starch composition into the fiber
slurry; forming the paper and paperboard materials; heating the
paper and paperboard materials at a temperature above the
activation temperature of the aldehyde generating compound or
glyoxal releasing compound and which is sufficient to dry the
paper.
[0040] Starch sources useful in the practice of the present
invention include, for example, potato, corn, waxy corn, red milo,
white milo, wheat, tapioca, and the like. Preferred starch sources
include potato, corn and wheat. Preferably, the starch composition
comprises a self retaining starch, i.e. a starch having a net
cationic charge. In particular starches containing cationic or a
combination of cationic and anionic functional groups, the
so-called amphoteric starches, including all the known commercial
cationic and amphoteric starches, can be used. More preferably, the
starch composition, which comprises a commercial pregelatinized
cationic starch such as, but not limited to, those sold by Penford,
Grain Processing Corporation (GPC), National Starch, Raisio and
Staley, are suitable for use in the compositions and paper making
methods provided by the invention.
[0041] In addition to the pre-gelatinized starches, any of the mill
cooked starches commonly used in the wet-end of the paper machine
can be used if cooled prior to addition of the glyoxal releasing
compound.
[0042] Gelatinized starch composition suitable for use in the paper
making methods of the invention generally comprise between about
0.5% to about 50% of at least one aldehyde generating compound or
glyoxal releasing compound based on the combined dry weight of the
starch and aldehyde generating compound or glyoxal releasing
compound. Preferred gelatinized starch compositions comprise
between about 0.5% and about 10, or 15, or 20, or 25, or 30% by dry
weight of at least one aldehyde generating compound or glyoxal
releasing compound.
[0043] The gelatinized starch compositions of this invention can be
used alone or in combination with other separately added strength
developing additives commonly used in papermaking. These include
cationic guar gum, cationic hemicelluloses, chitosan, anionic
polyacrylamide strength resins as described in U.S. Pat. No.
5,543,446, cationic reactive polyacrylamide strength resins as
described in U.S. Pat. No. 3,556,932, and the various types of
commercial wet strength resins including the common and well known
aminopolyamide-epichlorohydrin and melamine- or urea-formaldehyde
resins. They also can be used in combination with the separately
added starch added to the wet end or as a surface treatment, as is
commonly practiced in the papermaking process to develop strength
or improve other aspects of papermaking.
[0044] In particularly preferred methods of the invention, the
aldehyde generating compound thermally degrades at the temperature
sufficient to dry paper thereby releasing or generating enough
aldehyde groups to crosslink the starch and/or fiber. Preferred
aldehyde generating compounds generate one or more equivalents of
glyoxal and/or glyoxal equivalents during the thermal degradation.
More preferably, at least a portion of the released glyoxal from
the thermal degradation of the aldehyde generating compound reacts
with functional groups present in the starch or on the fiber
surface to form covalent crosslinks between two starch molecules or
particles or between starch and fiber.
[0045] In preferred methods of making paper provided by the
invention, the aldehyde generating compound is a glyoxal releasing
compound which comprises a reaction product of at least one molar
equivalent of glyoxal with between about 0.25 and about 5 molar
equivalents of one or more stabilizing agents. More preferably, the
glyoxal releasing compound comprises the reaction product of
between one and three equivalents of glyoxal and between one and
two, three or four equivalents of one or more stabilizing
agents.
[0046] Typically preferred stabilizing agents suitable for use in
the glyoxal releasing compounds or aldehyde generating compounds of
the invention include those chemical compounds capable of reacting
with at least one and preferably at least two aldehyde groups to
form one or two thermally labile functional groups which release an
unblocked aldehyde functional group when heated above an activation
temperature. In preferred embodiments, the activation temperature
is between about 75.degree. C. and about 250.degree. C., more
preferably the activation temperature is between about 90.degree.
C. and about 150.degree. C.
[0047] In preferred methods of making paper, the gelatinized starch
composition may comprise a glyoxal releasing compound prepared by
the reaction of
[0048] at least one molar equivalent of glyoxal; and
[0049] between about 0.5 and about 3 molar equivalents of
stabilizing agents selected from the group consisting of optionally
substituted urea, optionally substituted thiourea, optionally
substituted imidazolidin-2-one, and optionally substituted
tetrahydro-pyrimidin-2-one- .
[0050] In certain preferred methods of making paper provided by the
present invention, the gelatinized starch composition further
comprises one or more aldehyde blocking compounds which are capable
of reversibly blocking residual aldehyde residues present in the
gelatinized starch composition, e.g., unblocked aldehyde groups in
the aldehyde generating compound, the glyoxal releasing compound or
aldehyde groups present in glyoxal containing byproducts which may
be generated during the synthesis of the glyoxal releasing
compound. In preferred embodiments, aldehyde blocking compounds can
be selected from amines, particularly alkyl amines, alcohols such
as alkanols, alkylene glycols and other aldehyde blocking
compounds, which liberate a free aldehyde upon exposure to elevated
temperatures. Certain preferred aldehyde blocking compounds
include, for example, methanol, ethanol, 1- and 2-propanol,
propylene glycol, and the like.
[0051] In preferred papermaking methods of the invention, the
gelatinized starch composition may further comprise one or more
optionally substituted C.sub.1-20alcohol, optionally substituted
C.sub.2-20alkylene glycol or a combinations thereof may be also
incorporated, as an aldehyde blocking compound to block residual
aldehydes present in the aldehyde generating compound, the glyoxal
releasing compound or aldehyde groups present in byproducts
produced during the preparation of the glyoxal releasing
compound.
[0052] More preferably, paper making methods of the invention
comprise the use of a glyoxal releasing compound which is the
reaction product of
[0053] between 0.5 and 2 molar equivalent of glyoxal; and
[0054] between about 1 and about 3 molar equivalent of stabilizing
agents selected from the group consisting of urea, thiourea,
4,5-dihydroxy-imidazolidin-2-one, and
4-hydroxy-5-(C.sub.1-10-alkyl)-tetr- ahydro-pyrimidin-2-one.
[0055] Particularly preferred gelatinized starch compositions which
are suitable for use in the paper making processes of the invention
include compositions in which the glyoxal releasing compound is the
reaction product of glyoxal and at least one stabilizing agent
selected from urea, thiourea, 4,5-dihydroxy-imidazolidin-2-one, and
4-hydroxy-5-(C.sub.1-10-a- lkyl)-tetrahydro-pyrimidin-2-one and
further comprise at least 10 molar percent of an aldehyde blocking
compound selected from propylene glycol, methanol, ethanol,
n-propanol, and isopropanol.
[0056] In other preferred methods of making paper, the aldehyde
generating compound is a compound according to Formula I: 2
[0057] wherein
[0058] A is an optionally substituted methylene group, an
optionally substituted .alpha.,.omega.-C.sub.2-4alkylene, or a
single bond;
[0059] B is carbonyl, thiocarbonyl, or an optionally substituted
1,2-ethylene residue;
[0060] X.sub.1 and X.sub.2 are independently selected from the
group consisting of oxygen and NR.sub.3;
[0061] R.sub.1 and R.sub.2 are independently selected from the
group consisting of hydrogen, hydroxyl, optionally substituted
C.sub.1-20alkyl, optionally substituted C.sub.1-20alkoxy,
optionally substituted urea, optionally substituted thiourea,
or
[0062] R.sub.1 and R.sub.2, taken in combination, form a
N,N'-divalent urea;
[0063] R.sub.3 is independently selected at each occurrence of
R.sub.3 from the group consisting of hydrogen, optionally
substituted C.sub.1-20alkyl, and blocked glyoxal residues, where
the blocked glyoxal residue is a 1-hydroxy-2-(protected aldehyde
residue)-ethan-1-yl group;
[0064] wherein the aldehyde generating compound according to
Formula I thermally degrades to generate at least one equivalent of
a poly(aldehyde) compound when heated above an activation
temperature; and
[0065] wherein the aldehyde blocking compound loading is at least
10 molar % of the aldehyde generating compound.
[0066] Preferred aldehyde generating compounds of Formula (I) are
glyoxal releasing compounds. More preferred glyoxal releasing
compounds according to Formula I include those compounds wherein
(i) A is a single bond and R.sub.1 and R.sub.2 are hydroxyl, or
(ii) R.sub.3 contains a glyoxal residue that can generate glyoxal,
or compounds satisfying both conditions (i) and (ii).
[0067] Preferred glyoxal releasing compounds according to Formula I
which are suitable for use in the paper making methods of the
invention include those compounds in which:
[0068] R.sub.1 and R.sub.2 are independently selected from the
group consisting of hydrogen, hydroxyl, methanol, ethanol, urea,
or
[0069] R.sub.1 and R.sub.2, taken in combination, form a
N,N'-divalent urea;
[0070] R.sub.3 is independently selected at each occurrence of
R.sub.3 from the group consisting of hydrogen, methyl, and ethyl,
or
[0071] R.sub.3 is a blocked glyoxal residue selected from the group
consisting of 1,2-dihydroxy-2-(C.sub.1-4-alkoxy)-ethan-1-yl,
1,2-dihydroxy-2-(3-hydroxypropoxy)-ethan-1-yl, and
1,2-dihydroxy-2-(2-hydroxypropoxy)-ethan-1-yl.
[0072] Other preferred glyoxal releasing compounds according to
Formula I which are suitable for use in the paper making methods of
the invention include those compounds in which:
[0073] X.sub.1 and X.sub.2 are NR.sub.3;
[0074] A is a single bond;
[0075] B is a carbonyl or thiocarbonyl group; and
[0076] R.sub.1 and R.sub.2 are independently selected from
hydroxyl, C.sub.1-6alkoxy, or blocked glyoxal residues.
[0077] Still other preferred glyoxal releasing compounds according
to Formula I which are suitable for use in the paper making methods
of the invention include those compounds in which:
[0078] X.sub.1 and X.sub.2 are NR.sub.3;
[0079] A is a 1,1-C.sub.1-6alkylene group;
[0080] B is a carbonyl or thiocarbonyl group;
[0081] R.sub.1 and R.sub.2 are independently selected from
hydrogen, hydroxyl, C.sub.1-6alkoxy, or blocked glyoxal residues;
and
[0082] R.sub.3 is a blocked glyoxal residue selected from the group
consisting of 1,2-dihydroxy-2-(C.sub.4-alkoxy)-ethan-1-yl,
1,2-dihydroxy-2-(3-hydroxypropoxy)-ethan-1-yl, and
1,2-dihydroxy-2-(2-hydroxypropoxy)-ethan-1-yl.
[0083] Particularly preferred aldehyde generating compound or
glyoxal releasing compounds suitable for use in the paper making
processes of the invention include, but are not limited to, the
following compounds: 3
[0084] Each of which may optionally be mixed with one or more
aldehyde blocking compounds such as from propylene glycol,
methanol, ethanol, n-propanol, and isopropanol. More preferably the
glyoxal releasing compounds are admixed with at least 10, 15, 20,
25, or more molar percent of an aldehyde blocking compound. While
not wishing to be bound by theory, addition of the aldehyde
blocking compound generally prevents the aldehyde generating
compound or glyoxal releasing compound from comprising unblocked
aldehyde residues and thereby increases the stability of
gelatinized starch compositions comprising one or more aldehyde
generating compound or glyoxal releasing compound provided by the
invention.
[0085] Other preferred methods of the invention include those in
which the starch component of the starch composition further
comprises a cationic starch which is functionalized with at least
one ammonium salt. More preferably, the ammonium salts incorporated
into the starch composition comprises an alkylated ammonium cation
and a small counter anion. Particularly preferred ammonium salts
include tetraalkylammonium halide salts, N-alkyl pyridinium halide
salts, or salts generated from the use of Dow Quat.TM. 180, a
common cationizing agent for preparing cationic starch.
[0086] Preferred starch compositions of the invention comprise a
self retaining starch, i.e. a starch having a net cationic charge.
In particular, commercial pregelatinized cationic starch such as,
but not limited to, those sold by Penford, Grain Processin
Corporation (GPC), National Starch, Raisio and Staley are suitable
for use in the gelatinized starch compositions provided by the
invention. Starch sources such as potato, corn, waxy corn, red
milo, white milo, wheat, tapioca, and the like may be used.
Preferred starch sources include potato, corn and wheat.
[0087] In addition to the pre-gelatinized starches any of the mill
cooked starches commonly used in the wet-end of the paper machine
may be used if cooled prior to addition of the aldehyde generating
compound or glyoxal releasing compound.
[0088] Gelatinized starch compositions of the invention typically
comprise between about 0.5% to about 50% of at least one aldehyde
generating compound or glyoxal releasing compound based on the
combined dry weight of the starch and aldehyde generating compound
or glyoxal releasing compound.
[0089] The gelatinized starch compositions of the invention
comprise the use of an aldehyde generating compound or a glyoxal
releasing compound which is stable in the presence of starch at
about room temperature. That is, gelatinized starch compositions of
the invention comprise an aldehyde generating compound or a glyoxal
releasing compound which does not substantially react with starch
at room temperature, that is the reaction with starch is
sufficiently sluggish as to preclude the accumulation of
significant amounts of the reaction product during routine storage
time periods.
[0090] In particularly preferred gelatinized starch compositions of
the invention, the aldehyde generating compound or glyoxal
releasing compound thermally degrades at the temperature sufficient
to dry paper or paperboard thereby releasing one or more
equivalents of glyoxal or reactive aldehyde groups. More
preferably, at least a portion of the aldehyde groups released from
the thermal degradation of the aldehyde generating compound or
glyoxal releasing compound reacts with functional groups of the
starch or fiber to form covalent crosslinks between two starch
moieties or between a starch moiety and a fiber.
[0091] In preferred gelatinized starch compositions of the
invention, composition comprises:
[0092] a self-retaining gelatinized starch;
[0093] at least one aldehyde blocking compound capable of blocking
aldehyde residues of glyoxal; and
[0094] an aldehyde generating compound according to the Formula I:
4
[0095] wherein
[0096] A is an optionally substituted methylene group, an
optionally substituted C.sub.2-4alkylene group, or a single
bond;
[0097] B is carbonyl, thiocarbonyl, or an optionally substituted
1,2-ethylene residue;
[0098] X.sub.1 and X.sub.2 are independently selected from the
group consisting of oxygen and NR.sub.3;
[0099] R.sub.1 and R.sub.2 are independently selected from the
group consisting of hydrogen, hydroxyl, optionally substituted
C.sub.1-20alkyl, optionally substituted C.sub.1-20alkoxy,
optionally substituted urea, optionally substituted thiourea,
or
[0100] R.sub.1 and R.sub.2, taken in combination, form a
N,N'-divalent urea;
[0101] R.sub.3 is independently selected at each occurrence of
R.sub.3 from the group consisting of hydrogen, optionally
substituted C.sub.1-20alkyl, and blocked glyoxal residues, where
the blocked glyoxal residue is a 1-hydroxy-2-(protected aldehyde
residue)-ethan-1-yl group;
[0102] wherein the aldehyde generating compound according to
Formula I thermally degrades to generate at least one equivalent of
glyoxal when heated above an activation temperature; and
[0103] wherein the aldehyde blocking compound loading is at least
10 molar % of the glyoxal releasing compound.
[0104] Preferred aldehyde generating compounds of Formula (1) are
glyoxal releasing compounds. More preferred glyoxal releasing
compounds according to Formula I include those compounds wherein
(i) A is a single bond and R.sub.1 and R.sub.2 are hydroxyl, or
(ii) R.sub.3 contains a glyoxal residue that can generate glyoxal,
or compounds satisfying both conditions (i) and (ii).
[0105] Particularly preferred gelatinized starch compositions of
the invention include those compositions which are a homogeneous
solution or a dispersion in an aqueous media.
[0106] Other preferred gelatinized starch composition comprise an
aldehyde generating compound or a glyoxal releasing compound
according to Formula I wherein the aldehyde generating compound or
glyoxal releasing compound reacts with starch or gelatinized starch
with a rate sufficiently slow to permit storage of the composition
for at least one day at room temperature. More preferably, the
gelatinized starch composition is stable for at least three days or
for at least seven days. Particularly preferred gelatinized starch
compositions are stable for two weeks or more or for a month or
more.
[0107] Other preferred gelatinized starch composition of the
invention include those compositions in which the aldehyde blocking
compound is selected from the group consisting of
C.sub.1-20alcohols, C.sub.2-20alkylene glycols, and
C.sub.1-20alkylamines. More preferably the aldehyde blocking
compound is selected from the group consisting of methanol,
ethanol, propanol (n-propanol, isopropanol, or a mixture thereof),
ethylene glycol, and propylene glycol.
[0108] Yet other preferred gelatinized starch composition of the
invention include glyoxal releasing compounds according to Formula
I wherein
[0109] R.sub.1 and R.sub.2 are independently selected from the
group consisting of hydrogen, hydroxyl, methanol, ethanol, urea,
or
[0110] R.sub.1 and R.sub.2, taken in combination, form a
N,N'-divalent urea;
[0111] R.sub.3 is independently selected at each occurrence of
R.sub.3 from the group consisting of hydrogen, methyl, and ethyl,
or
[0112] R.sub.3 is a blocked glyoxal residue selected from the group
consisting of 1,2-dihydroxy-2-(C.sub.1-4-alkoxy)-ethan-1-yl,
1,2-dihydroxy-2-(3-hydroxypropoxy)-ethan-1-yl, and
1,2-dihydroxy-2-(2-hydroxypropoxy)-ethan-1-yl.
[0113] Additional preferred gelatinized starch composition of the
invention include glyoxal releasing compounds according to Formula
I wherein
[0114] X.sub.1 and X.sub.2 are NR.sub.3;
[0115] A is a single bond;
[0116] B is a carbonyl or thiocarbonyl group; and
[0117] R.sub.1 and R.sub.2 are independently selected from
hydroxyl, C.sub.1-6alkoxy, or blocked glyoxal residues.
[0118] Still other preferred gelatinized starch composition of the
invention include glyoxal releasing compounds according to Formula
I wherein
[0119] X.sub.1 and X.sub.2 are NR.sub.3;
[0120] A is a 1,1-C.sub.1-6alkylene group;
[0121] B is a carbonyl or thiocarbonyl group;
[0122] R.sub.1 and R.sub.2 are independently selected from
hydrogen, hydroxyl, C.sub.1-6-alkoxy, or blocked glyoxal residues;
and
[0123] R.sub.3 is a stabilized glyoxal residue selected from the
group consisting of 1,2-dihydroxy-2-(C.sub.1-4-alkoxy)-ethan-1-yl,
1,2-dihydroxy-2-(3-hydroxypropoxy)-ethan-1-yl, and
1,2-dihydroxy-2-(2-hydroxypropoxy)-ethan-1-yl.
[0124] Particularly preferred gelatinized starch composition of the
invention include aldehyde generating compounds or glyoxal
releasing compounds according to Formula I, wherein the aldehyde
generating compound or glyoxal releasing compound comprises at
least one compound selected from the group consisting of compounds
of the formulae: 5
[0125] An aqueous self-retaining gelatinized starch composition
comprises a starch which is self-retaining due to a net cationic
charge. The net charge of the starch also assists the gelatinized
starch in absorbing and retaining the aldehyde generating compounds
or glyoxal releasing compound from the aqueous media of the
composition. The net charge of the starch may also increase the
strength of the interaction between the starch and aldehyde
generating compounds or glyoxal releasing compound and the surface
of the slightly anionic fiber of the pulp slurry.
[0126] Although not wishing to be bound by theory, the gelatinized
starch composition, e.g., the essentially unreacted mixture of
gelatinized starch and an aldehyde generating compounds, are
incorporated into the pulp slurry of the wet end of the paper
manufacturing process in an essentially unreacted form. After
consolidation of the paper or paperboard web, exposure of the web,
which comprises the gelatinized starch composition, to temperatures
sufficient to dry the sheet under commercial paper drying
conditions, which also induces degradation of the aldehyde
generating compound, thereby releasing reactive aldehyde groups or
glyoxal compounds having reactive aldehyde residues or a
combination thereof. After release from the aldehyde generating
compound, the reactive aldehyde groups or glyoxal compounds having
reactive aldehyde residues react with functional groups,
particularly hydroxyl and amine groups, from one or more starch
molecules or moieties or the fiber surface to generate covalent
bonds.
[0127] Gelatinized starch compositions provided by the invention
may be prepared by any suitable method of forming an admixture of
the aqueous starch solution and the aldehyde generating compound.
Typically the aldehyde generating compound is added to the aqueous
starch solution and the combined material is intimately mixed to
form a substantially homogeneous composition. Although the mixing
process may be carried out at room temperature, it is often
desirable to gently heat the mixture while mixing to reduce the
viscosity of the aqueous starch solution. In general, warming the
mixture to between about 25.degree. C. and about 40.degree. C. is
sufficient to reduce the viscosity without degradation of the
aldehyde generating compound or initiating a reaction between the
starch and the aldehyde generating compound. The blending or mixing
of the starch and aldehyde generating compound is typically
complete in less than 24 hours and is preferably complete in less
than about 12, 8, or 6 hours. In particularly preferred methods of
making the gelatinizes starch compositions of the invention the
mixing or blending step is complete in between about 1 and about 3
hours.
[0128] The shelf life of the gelatinized starch composition is
typically dependent upon, among other things, the concentration of
the starch, the concentration of the aldehyde generating compound,
the rate at which the starch will degrade back to its crystalline
form and the rate at which the aldehyde generating compound reacts
with the starch at ambient or storage temperature.
[0129] The shelf-life measurements as used herein refer to the
ability of the gelatinized starch composition to be transferred
between storage and reactor vessels by traditional pumping means
used in the papermaking industry. The gelatinized starch
compositions of the invention comprising of at least one aldehyde
generating compound or glyoxal releasing compound, has generally
reached its' shelf life limit when the gelatinized starch
composition can not be pumped from the storage vessel. A typical
starch composition can be defined to be transferable if its
viscosity is less than 15000 cps.
[0130] Stability of the gelatinized starch compositions of the
invention are typically measured based upon the viscosity
measurement of the composition. In general, any gelatinized starch
composition of the invention which has a viscosity of 10,000 cPs or
less after about one (1), two (2), or three (3) weeks, or more
preferably after one month, is considered to have sufficient
stability. Viscosity of the gelatinized starch compositions are
routinely measured suing a Brookfield viscometer having a #4
spindle rotating at 10 or 20 rpm.
[0131] In preferred methods of making paper provided by the present
invention the aldehyde generating compound or the glyoxal releasing
compound is generally a polar, non-ionic compound and,
consequently, has minimal affinity for direct interacting with
fiber present in the pulp slurry which is weakly anionic.
Applicants have surprisingly discovered that the preferred aldehyde
generating compound or glyoxal releasing compounds interact with
cationic starch molecules and are localized to the fiber of the
paper slurry when the cationic starch adheres to the fiber surface.
Although not wishing to be bound by theory, the interaction between
the cationic starch and the aldehyde generating compound or glyoxal
releasing compound is likely due, in part, to dipole or
electrostatic interactions between the starch and the aldehyde
generating compound or glyoxal releasing compound.
[0132] As used herein, "alkyl" is intended to include both branched
and straight-chain saturated aliphatic hydrocarbon groups, having
the specified number of carbon atoms. Examples of alkyl include,
but are not limited to, methyl, ethyl, n-propyl, i-propyl, n-butyl,
s-butyl, t-butyl, n-pentyl, and s-pentyl. Preferred alkyl groups
are C.sub.1-6 alkyl groups. Especially preferred alkyl groups are
methyl, ethyl, propyl, butyl, and 3-pentyl. The term C.sub.1-4
alkyl as used herein includes alkyl groups consisting of 1 to 4
carbon atoms, which may contain a cyclopropyl moiety. Suitable
examples are methyl, ethyl, and cyclopropylmethyl. The term "alkyl"
is also intended to include cycloalkyl and cycloalkylalkyl groups
where there term "cycloalkyl" is used as defined herein.
[0133] "Cycloalkyl" is intended to include saturated ring groups,
having the specified number of carbon atoms, such as cyclopropyl,
cyclobutyl, cyclopentyl, or cyclohexyl. Cycloalkyl groups typically
will have 3 to about 8 ring members.
[0134] "Alkenyl" is intended to include hydrocarbon chains of
either a straight or branched configuration comprising one or more
unsaturated carbon-carbon bonds, which may occur in any stable
point along the chain, such as ethenyl and propenyl. Alkenyl groups
typically will have 2 to about 8 carbon atoms, more typically 2 to
about 6 carbon atoms.
[0135] "Alkynyl" is intended to include hydrocarbon chains of
either a straight or branched configuration comprising one or more
carbon-carbon triple bonds, which may occur in any stable point
along the chain, such as ethynyl and propynyl. Alkynyl groups
typically will have 2 to about 8 carbon atoms, more typically 2 to
about 6 carbon atoms.
[0136] "Alkoxy" represents an alkyl group as defined above with the
indicated number of carbon atoms attached through an oxygen bridge.
Examples of alkoxy include, but are not limited to, methoxy,
ethoxy, n-propoxy, i-propoxy, n-butoxy, 2-butoxy, t-butoxy,
n-pentoxy, 2-pentoxy, 3-pentoxy, isopentoxy, neopentoxy, n-hexoxy,
2-hexoxy, 3-hexoxy, and 3-methylpentoxy. Alkoxy groups typically
have 1 to about 8 carbon atoms, more typically 1 to about 6 carbon
atoms.
[0137] In the papermaking process wood pulp is prepared, bleached
if required, cleaned, and run through a series of beaters or
refiners until it is a fine slush. At this point fillers and other
additives, such as the gelatinized starch compositions of the
invention, can be mixed in. When preparation is complete, the slush
is pumped onto a fast-moving wire screen where it becomes
consolidated into a continuous web or sheet of paper or
paperboard.
[0138] As the consolidating web travels with the moving wire,
excess water is drained away leaving a crude paper or paperboard
sheet. The sheet is then squeezed between rollers or presses to
remove some of the remaining water and to ensure uniform thickness
and smoothness. Finally, the web is run over a series of heated
rollers or heating devices to remove most of the remaining water.
The paper may be "finished" in any number of ways, including but
not limited to, surface treatments, calendaring, or coating. The
finished paper is spooled onto `parent rolls` termed the reel.
EXAMPLES
[0139] The present invention is further illustrated by the
following examples which should not be construed as limiting in any
way. The contents of all cited references (including literature
references, issued patents, published patent applications) as cited
throughout this application are hereby expressly incorporated by
reference. The practice of the present invention will employ,
unless otherwise indicated, conventional techniques, which are
within the skill of the art. Such techniques are explained fully in
the literature.
[0140] In the following example, laboratory handsheets were
prepared using the MK sheet forming device in semi-automatic mode.
Pulp was beaten to 300 CSF (Canadian Standard Freeness) using a
laboratory beater. Additions were made to a 1% slurry of the pulp
prior to addition to the headbox. Sheets (12.times.12") were formed
using conventional practice, pressed, and dried at 120.degree. C.
using 2 passes through a felted rotating cylinder dryer. A pass is
one rotation around the heated drum. The speed of this rotation is
adjustable. For this study the rotation took 1 minute. The pulp
slurries were prepared in ordinary tap water without pH adjustment.
Old Corrugated Containers (OCC) was obtained from commercial box
clippings.
Example 1
Preparation of a Mixture of 4,5-dihydroxy-imidazolidin-2-one and at
Least One Aldehyde Blocking Compound
[0141] A 1000 ml flask was charged with glyoxal (40% in water, 145
grams, 1 mole) and the contents of the flask were stirred and
warmed to 55.degree. C. Urea (50% in water, 120 grams, 1 mole) was
added to the stirred glyoxal solution over four hours at 55.degree.
C. To this mixture propylene glycol (38 grams, 0.5 moles) and a
catalytic amount of sulfuric acid (98%, typically about 1 gram) was
added. The reaction mixture was then heated to 70.degree. C. for
two hours to generate the product, of which the predominant
reaction produce had the structure, as follows: 6
Example 2
Preparation of a Cyclic Glyoxal with Pendant Blocked Glyoxal
Residues
[0142] A 1000 ml flask was charged with glyoxal (40% in water, 435
grams, 3 moles) and the contents of the flask were stirred and
warmed to 55.degree. C. Urea (50% in water, 120 grams, 1 mole) was
added to the stirred glyoxal solution over two hours at 55.degree.
C. A catalytic amount of sulfuric acid (98%, typically about 1
gram) was added to the reaction mixture to accelerate the
cyclization reaction. The reaction mixture was allowed to stir for
four hours and then propylene glycol (152 grams, 2 moles) was
added. The reaction mixture was then heated to 70.degree. C. for
two hours to generate the product, of which the predominant
reaction produce had the structure, as follows: 7
Example 3
Dry Strength Evaluation of Paper Manufactured with a Gelatinized
Starch Composition Comprising the Compound of Example 1 as the
Glyoxal Releasing Compound
[0143] A handsheet study demonstrating strength improvements
included one handsheet set prepared without a starch additive and
three sets of sheets with different starch compositions. Handsheets
are 15 gm (12 in.times.12 in). Sample 3A was a control OCC furnish
with no additives. Sets 3B thru 3D were made with the identical
furnish and conditions but a different starch additive was used in
each set.
[0144] Set 3B contained a cationic pregelatinized potato starch
(Penford PAR 6048AR, available from Penford Products, Inc.), at 10
lb/ton and is referred to herein as the "starch only" control. Set
3C was prepared with a gelatinized starch composition comprising a
mixture of Penford PAR 6048AR and the glyoxal releasing compound
provided in Example 1. The mixture was prepared by mixing the
glyoxal releasing compound into the Penford PAR 6048AR (25%) at
32.degree. C. over 1 hour with agitation. The resulting mixture had
a solids content of 23.7% by weight.
[0145] Set 3D was prepared using the same gelatinized starch
composition as was used in Set 3C except that the gelatinized
starch composition was prepared by mixing the glyoxal releasing
compound from Example 1 into a Penford PAR 6048AR at 90.degree. C.
over 30 minutes with agitation (pre-reaction process). In both 3C
and 3D the glyoxal releasing compound was blended into Penford PAR
6048AR at 10% by weight dry on dry. The combination was added to
the OCC slurry at 10 lb/ton.
1 TABLE I Sample Description Dry Tensile Shelf-Life 3A fiber
control 46.04 NA 3B starch control 47.26 6 months 3C cold blend
57.65 3 months 3D pre-reacted 55.72 3 weeks
[0146] The results demonstrate that the dry strength of the
paperboard was improved when the glyoxal releasing compound was
added to the starch. Performance in terms of strength development
and stability are best when the material is added to the starch
under mild conditions (example 3C). Moreover, treatment of the
gelatinized starch composition under the conditions of the
pre-reaction process reduces the stability of the starch
composition.
Example 4
Dry Strength Evaluation of Paper Manufactured with a Gelatinized
Starch Composition Comprising the Compound of Example 2 as the
Glyoxal Releasing Compound
[0147] A handsheet study demonstrating strength improvements
included one handsheet set prepared without a starch additive and
three sets of sheets with different starch compositions. Handsheets
are 15 gm (12 in.times.12 in). Sample 4A was a control OCC furnish
with no additives. Sets 4B thru 4D were made with the identical
furnish and conditions but a different starch additive was used in
each set.
[0148] Set 4B contained a cationic pregelatinized potato starch
(Penford PAR 6048AR), at 10 lb/ton and is referred to herein as the
"starch only" control. Set 4C was prepared with a gelatinized
starch composition comprising a mixture of Penford PAR 6048AR and
the glyoxal releasing compound provided in Example 2. The mixture
was prepared by mixing the glyoxal releasing compound into the
Penford PAR 6048AR (25%) at 32.degree. C. over 1 hour with
agitation. The resulting mixture had a solids content of 23.7% by
weight.
[0149] Set 4D was prepared using the same gelatinized starch
composition as was used in Set 4C except that the gelatinized
starch composition was prepared by mixing the glyoxal releasing
compound from Example 2 into Penford PAR 6048AR at 90.degree. C.
over 30 minutes with agitation (pre-reaction process). In both 4C
and 4D the glyoxal releasing compound was blended into Penford PAR
6048AR at 10% by weight dry on dry. The combination was added to
the OCC slurry at 10 lb/ton.
2 TABLE II Sample Description Dry Tensile Shelf-Life 4A fiber
control 46.04 NA 4B starch control 47.26 6 months 4C cold blend
52.47 1.5 days 4D pre-reacted ND <1 hour
[0150] The results demonstrate that the dry strength of the
paperboard was improved when the glyoxal releasing compound of
Example 2 was added to the gelatinized starch composition.
Performance in terms of strength development and stability were
best when the material was added to the starch under the mild
conditions (example 4C). Treatment of the gelatinized starch
composition with harsh conditions, such as those of set 4D,
resulted in a gelatinized starch composition that was not usable
for use in commercial applications, due in part to a short shelf
life.
Example 5
Preparation of Cyclic Amide with Pendent Blocked Glyoxal Units
[0151] Sodium bicarbonate (7.5 grams) was introduced into a sealed
nitrogen filled round bottom flask fixed with heating, cooling,
reflux, distillation, pH probe, temperature probe and constant
pressure addition apparatus. Formaldehyde (37% in water, 172 grams,
2 moles) was then added to the flask. Propionaldehyde (116 grams, 2
moles) was then slowly added to the reaction mixture over 2 hours
at 30.degree. C. Upon complete addition of the propionaldehyde, the
reaction solution was heated to 45.degree. C. for 4 hours. Urea
(120 grs (2 moles)) was then added and the temperature of the
reaction mixture increased to 60.degree. C. for 2 hours. Residual
raw materials and a small amount of reaction by-products were then
removed from the reaction flask by vacuum distillation. Sulfuric
acid (98%, 6.25 grams) was added to the material remaining in the
flask after distillation and the reaction mixture was held at
60.degree. C. for 4 hours.
[0152] Glyoxal (40% by weight in water; 290 grams, 2 moles) and
propylene glycol (152 grams, 2 moles) were added sequentially at
55.degree. C. to the reaction mixture. The reaction mixture was
allowed to stir for an hour after complete addition of each
reagent, e.g., glyoxal and propylene glycol.
[0153] The reaction mixture was returned to room temperature and
the pH was adjusted to about 6.5 by addition of sodium bicarbonate.
The predominate glyoxal releasing compound formed by the reaction
is represented by the structure, as follows: 8
Example 6
Dry Strength Evaluation of Paper Manufactured with a Gelatinized
Starch Composition Comprising the Compound of Example 5 as the
Glyoxal Releasing Compound
[0154] A handsheet study demonstrating strength improvements
included one handsheet prepared without a starch additive and three
sets of sheets with different starch compositions. Handsheets are
15 gm (12 in.times.12 in). Sample 6A was a control OCC furnish with
no additives. Sets 6B thru 6D were made with the identical furnish
and conditions but a different starch additive was used in each
set.
[0155] Set 6B contained a cationic pregelatinized potato starch
(Penford PAR 6048AR), at 10 lb/ton and is referred to herein as the
"starch only" control. Set 6C was prepared with a gelatinized
starch composition comprising a mixture of Penford PAR 6048AR and
the glyoxal releasing compound provided in Example 5. The mixture
was prepared by mixing the glyoxal releasing compound into the
Penford PAR 6048AR (25%) at 32.degree. C. over 1 hour with
agitation. The resulting mixture had solids of 23.7%.
[0156] Set 6D was prepared using the same gelatinized starch
composition as was used in Set 6C except that the gelatinized
starch composition was prepared by mixing the glyoxal releasing
compound from Example 5 into Penford PAR 6048AR at 90.degree. C.
over 30 minutes with agitation (pre-reaction process). In both 6C
and 6D the glyoxal releasing compound was blended into Penford PAR
6048AR at 10% by weight dry on dry. The combination was added to
the OCC slurry at 10 lb/ton.
3 TABLE III Sample Description Dry Tensile Shelf-Life 6A fiber
control 46.04 NA 6B starch control 47.26 6 months 6C cold blend
57.47 1 month 6D pre-reacted 56.41 5 days
Example 7
Production Scale Paper Manufactured Using Gelatinized Starch
Composition in Which the Glyoxal Releasing Compound is the Compound
Provided by Example 1
[0157] A 10 tote trial of a gelatinized starch composition was
prepared by mixing the comprising a glyoxal releasing compound
provided by Example 1 and Penford PAR 6048AR cationic potato starch
(7%:93% by weight of glyoxal releasing compound:starch) to give a
final combined concentration of 21% (less than 3000 cps). The
gelatinized starch composition was added to the paper making
process at several locations in the wet end of the paper making
process, such as the suction side of the machine chest fan pump and
the suction side of the pressure screen. During this trial the
average dosage rate of the gelatinized starch composition was about
10 pounds per ton.
[0158] The paper manufacturing method using the gelatinized starch
composition having a glyoxal releasing compound provided by Example
1 provides the following benefits: (1) reduced the basis weight of
the paperboard by approximately 1.5%; (2) increased the speed of
the machine by approximately 6%; (3) maintained the ring crush and
Mullen test parameters of the paperboard while the speed was
increased and the basis weight was reduced; (4) increased drainage
from the consolidated web; (5) reduced filler machine chest
turbidity; and (6) reduced white water turbidity.
Example 8
Preparation of a Cyclic Glyoxal Compound with Pendant Glyoxal
Residues and No Aldehyde Blocking
[0159] A 1000 ml flask was charged with glyoxal (40% in water, 435
grams, 3 moles) and sulfuric acid (98%, 2 grams) and was stirred
and warmed to 65.degree. C. Urea (50% in water, 120 grams, 1 mole)
was added to the stirred glyoxal solution over four hours at
65.degree. C. The reaction mixture was held for two hours at
70.degree. C. to generate the product, of which the predominant
reaction product had the structure, as follows: 9
Example 9
Demonstration of Stability for glyoxal Releasing Compounds in a
Self-Retaining Starch Solution
[0160] Penford PAR 6048AR cationic potato starch was blended with
the glyoxal releasing compounds taken from example 1, 5, and 8. In
addition, unreacted/unblocked glyoxal was used as a comparison. The
blending was done at ambient temperature and for 30 minutes. The
blend ratio and starch solids are listed in Table IV. A Brookfield
RV viscometer (spindle #5/10 rpm/25.degree. C.) was used to measure
the viscosity.
4TABLE IV 10% Active Starch Solids 15% Active crosslinker
Crosslinker Viscosity Glyoxal Example #1 Example #8 Example #5 2
Hours Gel (0.5 hr) 300 cPs Gel (0.5 hr) 350 cPs 4 Hours Gel 300 cPs
Gel 300 cPs 6 Hours Gel 300 cPs Gel 300 cPs 8 Hours Gel 300 cPs Gel
300 cPs 24 Hours Gel 300 cPs Gel 300 cPs
[0161] The results in Table IV demonstrate that the blocked
aldehyde containing compounds of type demonstrated in Examples 1
and 5 can produce stable mixtures with starch while unblocked
aldehyde containing compounds, like that of example 8, and glyoxal
will not produce stable mixtures with starch.
[0162] The disclosures of all articles and references mentioned in
this application, including patents, are incorporated herein by
reference.
[0163] The invention and the manner and process of making and using
it, are now described in such full, clear, concise and exact terms
as to enable any person skilled in the art to which it pertains, to
make and use the same. It is to be understood that the foregoing
describes preferred embodiments of the present invention and that
modifications may be made therein without departing from the spirit
or scope of the present invention as set forth in the claims. To
particularly point out and distinctly claim the subject matter
regarded as invention, the following claims conclude this
specification.
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