Wet strength resin from aminopolyamide-polyureylene

Disclosed are novel wet strength resins for paper. The resins are produced by reacting an epihalohydrin, such as epichlorohydrin, with an aminopolyamide-polyureylene intermediate derived by reacting methylbisaminopropylamine with oxalic acid or a diester of oxalic acid and with urea.

This invention relates to the synthesis of wet and dry strength resins for 
use in the manufacture of paper, the broke of which can be easily and 
readily repulped. 
Broke is a waste product of the paper industry which, if not recovered and 
utilized, represents a substantial loss. It is customary to repulp the 
broke and reuse it in the paper-making process. Wet strength broke is 
difficult to repulp and the repulping of wet strength broke is discussed 
by Schmalz in TAPPI, Vol. 44, pages 275-280 (April 1961). 
Cationic, water-soluble, thermosetting resins derived by the reaction of 
polyaminoureylenes with epichlorohydrin are known wet strength resins for 
paper. Typical of these resins are the resins of U.S. Pat. No. 3,240,664 
to Earle, Jr. derived by the reaction of epichlorohydrin and a 
polyaminoureylene produced from a polyalkylene polyamine containing a 
tertiary amine group such as methylbisaminopropylamine and urea. Cationic, 
water-soluble thermosetting resins produced by reaction of epichlorohydrin 
and an aminopolyamide (sometimes referred to as a polyaminoamide or 
polyaminopolyamide) derived from a C.sub.3 to C.sub.10 saturated 
dicarboxylic acid and methylbisaminopropylamine are also known and 
described, for example, in U.S. Pat. No. 3,311,594 to Earle, Jr. See also 
U.S. Pat. No. 3,793,279 to Lipowski, U.S. Pat. No. 3,887,510 to Chan et 
al. and U.S. Pat. No. 3,891,589 to Ray-Chaudhuri which disclose the use of 
diesters derived from C.sub.2 to C.sub.20 saturated dicarboxylic acids in 
the preparation of aminopolyamides which are subsequently reacted with 
epichlorohydrin. Further, in U.S. Pat. No. 3,793,279, Lipowski teaches 
producing cationic wet strength resins by reacting certain chain-extended, 
amine-terminated base polyamides with epichlorohydrin and discloses that 
the broke from papers which are treated with these resins is more easily 
recovered than broke from paper treated with other wet strength resins 
such as those disclosed in U.S. Pat. No. 2,926,154 to Keim. Lipowski also 
indicates that acids which decarboxylate, such as oxalic acid, are not 
suitable for making wet strength resins and shows that the products 
prepared from diethylenetriamine and oxalic acid, with or without 
subsequent amine termination and chain extension do not, upon reaction 
with epichlorohydrin, provide cationic resins having wet strength 
properties. 
Now in accordance with this invention it has been found that the resins 
prepared by reacting an epihalohydrin, such as epichlorohydrin, with 
aminopolyamide-polyureylene intermediates derived by the reaction of 
methylbisaminopropylamine with oxalic acid or its diester and with urea 
impart good wet strength to paper and that the paper can be repulped using 
relatively mild repulping conditions. Accordingly, the present invention 
relates to a process for preparing an aqueous solution of a water-soluble, 
cationic thermosetting resin which process comprises reacting 
methylbisaminopropylamine with (a) oxalic acid or a diester of oxalic acid 
and (b) urea to form an aminopolyamide-polyureylene intermediate 
containing tertiary amine groups, the mole ratio of (a) to (b) being from 
about 0.1:1 to about 10:1 and the mole ratio of methylbisaminopropylamine 
to (a) plus (b) being from about 0.9:1 to about 1.2:1, and reacting the 
intermediate in aqueous solution with from about 1 mole to about 1.5 moles 
of an epihalohydrin per mole of tertiary amine groups present in said 
intermediate. 
In the preparation of the resins of this invention oxalic acid or its 
diester and urea are contacted with methylbisaminopropylamine to produce a 
reaction intermediate containing amide and ureylene linkages. The 
preferred diesters of oxalic acid are the lower alkyl esters and 
particularly dimethyl oxalate, diethyl oxalate, and dipropyl oxalate. The 
methylbisaminopropylamine reactant, also referred to in the art as 
N-bis(aminopropyl)methylamine, has the formula 
##STR1## 
Reaction of oxalic acid or its diester and urea with the amine is 
preferably carried out neat, but can also be carried out in a solution or 
dispersion of the reactants in a suitable solvent such as water, alcohols 
and the like. In the usual procedure oxalic acid or its diester is added 
gradually to the amine over a period of time sufficient to maintain the 
temperature at about 100.degree.-125.degree. C. to prevent decomposition 
of the acid or ester prior to reaction with the amine. Next the 
temperature is raised to about 150.degree. C. to about 200.degree. C. and 
maintained thereat for a length of time sufficient to remove the water of 
polycondensation and produce the diamide of oxalic acid. Then sufficient 
urea is added to react with substantially all of the unreacted 
methylbisaminopropylamine remaining in the reaction mixture and the 
temperature is maintained at about 120.degree. to 240.degree. C. and 
preferably between about 150.degree. C. and 200.degree. C. for about 1/2 
to 2 hours to complete the reaction. Time of reaction depends on 
temperature and is inversely proportional thereto. Usually a total of from 
about 3 to about 7 hours are required to complete the reaction of oxalic 
acid or its diester and urea with the amine. 
In the above reaction, the mole ratio of oxalic acid or its diester to urea 
will range from about 0.1:1 to about 10:1, preferably from about 0.2:1 to 
about 4:1 and more preferably from about 0.25:1 to about 4:1 and the 
preferred mole ratio of methylbisaminopropylamine to total acid 
components, i.e. oxalic acid or its diester plus urea, is from about 0.9:1 
to about 1.2:1 and more preferably about 1:1. 
In converting the polyamide-polyureylene intermediate to a water-soluble, 
cationic, thermosetting resin, the polyamide-polyureylene is reacted in 
aqueous solution with an epihalohydrin, preferably epichlorohydrin. The 
reaction is carried out in solution, using the polyamide-polyureylene 
intermediate in the form of its water-soluble acid salt in those cases 
where the free amine form has limited water solubility. Usually the pH of 
the aqueous solution of the intermediate is adjusted to about 8.5 to about 
9.6 before or immediately after the addition of the epihalohydrin, and the 
temperature of the reaction medium is maintained at from about 40.degree. 
C. to about 100.degree. C. and preferably from about 45.degree. C. to 
85.degree. C. until the viscosity of a 25% solids solution at 25.degree. 
C. has reached about E-F or higher on the Gardner-Holdt scale or the 
Spence-Spurlin viscosity is at least about 20 and preferably ranges from 
about 22 to about 30 seconds. 
The acid salt of the aminopolyamide-polyureylene intermediate is easily and 
readily prepared by adding to an aqueous dispersion of the intermediate a 
water-soluble acid such as hydrochloric acid in an amount essentially 
stoichiometrically equivalent to the tertiary amines of the 
aminopolyamide-polyureylene intermediate whereby essentially all the 
tertiary amines are converted to the ammonium salt. Suitable acids for 
salt formation are water-soluble, are within the skill of the art and 
include inorganic acids such as sulfuric acid, hydrochloric acid, nitric 
acid and phosphoric acid and organic acids such as acetic acid. 
In the aminopolyamide-polyureylene-epihalohydrin reaction, it is preferred 
to use sufficient epihalohydrin to convert all tertiary amine groups to 
quaternary ammonium groups. Satisfactory resins can be prepared by using 
from about 1 mole to about 1.5 moles and preferably from about 1.2 to 
about 1.4 moles of epihalohydrin per mole of tertiary amine of the 
intermediate. When the desired viscosity is reached, sufficient additional 
water is added to adjust the solids content of the resin solution to about 
15% or less and the product is cooled to room temperature, about 
25.degree. C. The resin will contain a plurality of reactive 
##STR2## 
groups. 
The resin is preferably stabilized against premature gelation by converting 
essentially all the reactive 
##STR3## 
groups to inactive 
##STR4## 
groups, X being the halogen of the epihalohydrin and chlorine when the 
epihalohydrin is epichlorohydrin. 
The stabilization is accomplished by adding a water-soluble acid, 
preferably a hydrogen halide acid such as hydrochloric acid to the resin 
solution until essentially all the reactive groups are changed to the 
inactive form. This is accomplished by adding sufficient water-soluble 
acid to obtain and maintain a pH of from about 1 to 3. The reactive groups 
are thereby changed to the inactive form and the resin solution will be 
stabilized against gelation. When the pH remains at the desired pH for a 
period of about one-half hour at room temperature (about 25.degree. C.) it 
is relatively certain the pH will not change and the resin solution is 
stabilized against gelation. By this means, stable solutions having a 
resins solids content of from about 10% to about 50% can be prepared. 
Hydrogen halide acids that can be employed in the above stabilization 
procedure are hydrochloric acid, hydrobromic acid, hydrofluoric acid, and 
hydroiodic acid. Water-soluble acids other than hydrogen halide acids can 
be used if the halide ion concentration of the reaction mixture is 
sufficiently high, e.g., at least 0.1N, and the reactivity or 
nucleophilicity of the acid anion is sufficiently low that the epoxide 
groups are converted essentially completely to the halohydrin. Examples of 
other water-soluble acids that can be employed include sulfuric acid, 
nitric acid, phosphoric acid and acetic acid. Mixtures of two or more 
water-soluble acids can be used if desired. 
Prior to use in the paper mill the stabilized resin is "reactivated" by 
adjusting the pH of the resin solution to and maintaining it above 8, 
preferably 10.5 and higher. Preferred pH range is 10.5 to 12.0. This 
reconverts essentially all the inactive 
##STR5## 
groups to the reactive cross-linking 
##STR6## 
groups. This pH adjustment is made by the addition of a suitable organic 
or inorganic base such as the alkali metal hydroxides and carbonates, 
calcium hydroxide, benzyltrimethylammonium hydroxide, and 
tetramethylammonium hydroxide. The alkali metals include sodium, 
potassium, cesium and lithium. The base is added preferably as an aqueous 
solution. 
The resins, prepared as herein described, may be incorporated into pulp 
slurry at any point on the wet end of the paper machine. However, prior to 
use, the stabilized resin must be reactivated as above set forth to 
convert the halohydrin groups to epoxide groups. 
The resins of this invention exhibit high "off-the-machine" wet strength 
and moderate to high dry strength. For most purposes, adequate wet 
strength can be obtained by incorporating into the paper from about 0.2% 
to about 3% of the resin based on the dry weight of the pulp.

The invention is further illustrated by the following examples which 
demonstrate the best known embodiments of the invention. In these 
examples, intrinsic viscosity (I.V.) measurements were determined at 
25.degree. C. on a 2% solution in 1M ammonium chloride and Brookfield 
viscosity measurements were determined at 25.degree. C., using a #1 
spindle at 60 r.p.m. unless otherwise indicated. 
EXAMPLE 1 
Part A 
Methylbisaminopropylamine (145.3 grams, 1 mole), urea (48.0 grams, 0.8 
mole) and dimethyl oxalate (23.6 grams, 0.2 mole) were charged to a 
reaction vessel equipped with stirrer, thermometer, heating mantle, 
nitrogen sparge and water trap with condenser. The charge was heated 
gradually to 125.degree. C., maintained at 125.degree. C. for 20 minutes 
and then heated to 240.degree. C. over a period of about 2 hours, the 
methanol and urea by-products being collected during the course of the 
reaction. The reaction mass was held at 240.degree. C. for about 25 
minutes, following which time the temperature was reduced to 130.degree. 
C. Next, 97.8 grams of 37% aqueous HCl and 116 ml of water were added and 
the mixture was thoroughly agitated at 100.degree. C. for about 1 hour to 
provide an aqueous solution of the resulting salt, additional aqueous HCl 
being added as necessary to maintain the pH below 5.6. A clear yellow 
viscous solution having a pH of 4.55 and a solids content of 54.5% was 
obtained. Examination of the solid product by nuclear magnetic resonance 
(C.sub.13 NMR) indicated that the product was an 
aminopolyamide-polyureylene containing 20 mole % of oxamide moieties. The 
product had an I.V. of 0.163. 
Part B 
52.5 grams of the solution of Part A, 160.2 ml of water and 17.4 grams 
(0.188 mole) of epichlorohydrin were placed in a reaction vessel and the 
pH of the solution was adjusted to 9.6 with 21.1 grams of 20% aqueous 
NaOH. The temperature of the resulting solution was raised to 
65.degree.-70.degree. C. and the viscosity of the solution was monitored. 
When the Spence-Spurlin viscosity reached 10 seconds, additional 20% 
aqueous NaOH was added to adjust the pH to 8.2. When the Spence-Spurlin 
viscosity reached 23 seconds, 40 ml of water were added and the pH was 
adjusted to 2 with 37% aqueous HCl. Periodic pH adjustments were made 
until the pH of 2 was constant for about 30 minutes. The resulting 
solution had a solids content of 18.7% by weight and a Gardner-Holdt 
viscosity of C at 25.degree. C. 
EXAMPLE 2 
Part A 
Methylbisaminopropylamine (1.0 mole) and dimethyl oxalate (0.4 mole) were 
charged to a reaction vessel equipped with stirrer, thermometer, heating 
mantle, nitrogen sparge and water trap with condenser and the charge was 
heated gradually to 150.degree. C. over a period of 1 hour. The charge was 
maintained at 150.degree. C. until most of the methanol by-product was 
collected and then the temperature was lowered to 90.degree. C. Next, urea 
(0.6 mole) was added to the vessel and the temperature was increased 
incrementally to 225.degree. C. over about a 2 hour period at which time 
ammonia liberation had ceased and the reaction was considered complete 
(based on titration of the ammonia collected). The temperature of the 
reaction product was lowered to 130.degree. C. and the product was 
thoroughly mixed with 101.2 grams of 37.3% aqueous HCl and 120 ml of water 
to provide a 55.0% aqueous solution of the resulting salt, the pH of the 
solution being 3.90. Examination of the solid product by C.sub.13 NMR 
indicated that the product was an aminopolyamide-polyureylene containing 
40 mole % of oxamide moieties. The product had an I.V. of 0.168. 
Part B 
59.7 grams of the solution of Part A, 176 ml of water and 18.8 grams (0.203 
mole) of epichlorohydrin were placed in a reaction vessel and the pH of 
the solution was adjusted to 9.20 with 21.1 grams of 20% aqueous NaOH. The 
temperature of the resulting solution was raised to 65.degree.-67.degree. 
C. and the viscosity of the solution was monitored. When the 
Spence-Spurling viscosity reached 2.5 seconds, additional 20% aqueous NaOH 
was added to adjust the pH to 8.00. When the Spence-Spurlin viscosity 
reached 25.0 seconds, 100 ml of water were added and the pH was adjusted 
to 2 with 37% aqueous HCl. Periodic pH adjustments were made until the pH 
of 2 was constant for about 30 minutes. The resulting solution had a 
solids content of 13.6% by weight and a Gardner-Holdt viscosity of B at 
25.degree. C. 
EXAMPLES 3 AND 4 
A 50:50 by weight mixture of Rayonier bleached kraft pulp and Weyerhaeuser 
bleached hardwood kraft pulp was beaten to a Canadian Standard freeness of 
500 cc in a Noble and Wood cycle beater. The pulp was then adjusted to pH 
7.5 with 10% NaOH and varying amounts, as specified in Table I, based on 
the dry weight of pulp, of the aminopolyamide-polyureyleneepichlorohydrin 
resins prepared in Examples 1 and 2 were added. The solutions of Examples 
1 and 2 were reactivated for use by diluting 20 grams of each solution to 
about 3% solids with water, and adding, with mixing, sufficient 1N sodium 
hydroxide and water to provide a solution having a resin solids content of 
about 2% and a pH of about 11. The pulp was sheeted on a Noble and Wood 
handsheet machine to provide handsheets having a basis weight of 
approximately 40 pounds per ream (3000 square feet) and the resulting 
handsheets were wet pressed to a 33% solids content and then dried at 
105.degree. C. for 45 seconds on a steam heated drum drier to 3-4% 
moisture. The dry strength was tested "uncured" (after 7 days of natural 
aging) or "cured" (after 30 minutes at 80.degree. C.). The sheets tested 
for wet strength were soaked for two hours in distilled water. Results are 
listed in Table I. 
TABLE I 
______________________________________ 
Ad- 
di- Tensile Strength (lbs/inch) 
tion Dry Wet 
Ex. Resin % of Basis Un- Un- 
No. of pulp Weight 
cured Cured cured Cured 
______________________________________ 
3 Ex. 1 0.25 39.9 21.8 23.2 3.94 4.43 
0.50 39.6 22.0 22.2 4.98 5.44 
0.75 39.9 24.8 26.5 5.84 6.55 
4 Ex. 2 0.25 40.0 21.9 24.2 3.99 4.35 
0.50 39.5 23.6 25.6 5.40 6.01 
0.75 39.9 24.4 23.8 5.23 5.86 
Blank -- 40.0 19.6 19.9 0.59 0.64 
______________________________________ 
EXAMPLE 5 
Part A 
Methylbisaminopropylamine (145.3 grams, 1.0 mole) was charged to a reaction 
vessel equipped with stirrer, thermometer, heating mantle, nitrogen sparge 
and water trap with condenser and the charge was heated to 130.degree. C. 
Anhydrous oxalic acid (43.2 grams, 0.48 mole) was dissolved in 70 ml of 
water at 70.degree.-75.degree. C. and the oxalic acid solution was added 
dropwise to the vessel over a period of about 40 minutes while maintaining 
the contents at 115.degree.-130.degree. C. After completion of the 
addition, the temperature was raised to 180.degree.-184.degree. C. over a 
period of about 3 hours and maintained thereat until the water was 
removed. The temperature of the reaction mass was next decreased to 
90.degree. C. and 31.3 grams (0.52 mole) of urea were added. The 
temperature of the mixture was gradually raised to 180.degree.-183.degree. 
C. and maintained thereat for 1.25 hours while the ammonia was removed. 
Next the temperature was reduced to about 150.degree. C. and the product 
was thoroughly mixed with 98.6 grams of 37% aqueous HCl and 160 ml of 
water to provide an aqueous solution of the resulting salt, the pH of the 
solution being 2.0. The resulting solution had a total solids of 48.6% by 
weight. Examination by C.sub.13 NMR indicated that the product was an 
aminopolyamide-polyureylene. The product had an I.V. of 0.183. 
Part B 
66.0 grams of the solution of Part A and 169 ml of water were charged to a 
reaction vessel and the charge was adjusted to a pH of 8.65 with 24.4 
grams of 20% aqueous NaOH. Epichlorohydrin (18.7 grams, 0.203 mole) was 
added giving 20% reaction solids, the temperature of the resulting 
solution was raised to 50.degree.-52.degree. C. and the viscosity of the 
solution was monitored. When the Spence-Spurlin viscosity reached 25 
seconds, 50 ml of water were added and the pH was adjusted to 2 with 37% 
aqueous HCl. The temperature was increased to 65.degree. C. and periodic 
pH adjustments were made until the pH of 2 was constant for about 1 hour. 
The resulting solution had a total solids content of 15.1% by weight and a 
Gardner-Holdt viscosity of C at 25.degree. C. 
EXAMPLE 6 
Part A 
Anhydrous oxalic acid (63.0 grams, 0.70 mole) and 100 ml of water were 
charged to a reaction vessel equipped with stirrer, thermometer, heating 
mantle, nitrogen sparge and water trap with condenser and the charge was 
heated to 110.degree. C. Methylbisaminopropylamine (145.3 grams, 1.0 mole) 
was added dropwise over a period of 50 minutes, following which time the 
temperature of the reaction mass was raised to 180.degree. C. over 2.83 
hours and maintained at 180.degree. C. until the water of polycondensation 
was removed. The temperature of the reaction mass was next reduced to 
50.degree. C. and urea (18.0 grams, 0.30 mole) was added. The temperature 
was then raised to 180.degree. C. over a period of 40 minutes and 
maintained at 180.degree. C. while the by-product ammonia was collected 
(about 35 minutes). The temperature was next decreased to 150.degree. C., 
102 grams of 37% aqueous HCl and 165.2 ml of water were added and the 
mixture was thoroughly agitated at 90.degree. C. to provide an aqueous 
solution of the resulting salt. A clear yellow viscous solution having a 
pH of 2.8, a solids content of 45.0% and an I.V. of 0.127 was obtained. 
Part B 
74.6 grams of the solution of Part A and 114 ml of water were charged to a 
reaction vessel and the charge was adjusted to a pH of 9.0 with 20.5 grams 
of 20% aqueous NaOH. Epichlorohydrin (18.0 grams, 0.195 mole) was added 
dropwise, giving 25% reaction solids, and the temperature was raised to 
50.degree. C. and the viscosity of the solution was monitored. When the 
Spence-Spurlin viscosity reached 30 seconds, 50 ml of water were added and 
the pH was adjusted to 0.5 with 10 grams of 37% aqueous HCl. The 
temperature was increased to 65.degree. C. and periodic pH adjustments 
were made until a pH of 2 was constant for about 30 minutes. The resulting 
solution had a total solids content of 19.0% by weight and a Gardner-Holdt 
viscosity of D+ at 25.degree. C. 
EXAMPLES 7 AND 8 
The resin solutions of Examples 5 and 6 were activated for use using the 
procedure set forth in Examples 3 and 4, and paper sheets were prepared 
using the resulting solutions and tested in accordance with the procedure 
of Examples 3 and 4. Strength properties of the sheets are set forth in 
Table II below. 
TABLE II 
______________________________________ 
Ad- 
di- Tensile Strength (lbs/inch) 
tion Dry Wet 
Ex. Resin % of Basis Un- Un- 
No. of pulp Weight 
cured Cured cured Cured 
______________________________________ 
7 Ex. 5 0.25 40.0 21.5 22.3 4.11 4.90 
0.50 40.0 25.0 25.7 5.46 6.47 
0.75 40.0 23.7 24.2 5.55 6.33 
8 Ex. 6 0.25 40.0 21.8 22.9 3.91 4.63 
0.50 40.0 22.3 23.5 4.83 5.87 
0.75 40.0 24.1 25.2 5.43 6.47 
Blank -- 40.0 19.3 19.5 0.64 0.65 
______________________________________ 
EXAMPLES 9 TO 11 
Handsheets were prepared in accordance with the procedure of Examples 3 and 
4 using 0.25% (based on the dry weight of the pulp) of the resins of 
Examples 2, 5 and 6. Samples of uncured handsheets were repulped in 
aqueous NaOH at a pH of 12 and at a temperature of 85.degree. C. Repulping 
of the paper sheets was carried out according to TAPPI method 205 m-58 at 
a mixer speed of 2800 r.p.m., a pulp consistency of 1.3% and a pH of 12. 
The degree of repulping (fiber separation) was measured and reported in 
integers ranging from 1-6, the integer 6 indicating substantially complete 
repulping. Test results are set forth in Table III below. 
TABLE III 
______________________________________ 
Ex. Resin Degree of Repulping (after minutes) 
No. of 5 10 20 30 40 50 
______________________________________ 
9 2 1 2 4 5 5 6 
10 5 &lt;1 2 4 5 6 
11 6 1 3 5 6 
______________________________________ 
EXAMPLE 12 
Part A 
Methylbisaminopropylamine (889.3 grams, 6.12 moles) and 50 ml of water were 
charged to a resin kettle equipped with stirrer, thermometer, heating 
mantle, nitrogen sparge and water trap with condenser and the charge was 
heated to 135.degree. C. Anhydrous oxalic acid (324.1 grams, 3.6 moles) 
was dissolved in 446 ml of water at 75.degree.-80.degree. C. and the 
oxalic acid solution was added dropwise to the kettle over a period of 1.5 
hours while maintaining the contents at 122.degree.-136.degree. C. After 
completion of the addition, the temperature was raised to 175.degree. C. 
over a period of 1.8 hours and maintained thereat until the water was 
removed. The temperature of the reaction mass was next decreased to 
90.degree. C. and urea (144.1 grams, 2.4 moles) was added. The temperature 
of the mixture was gradually raised to 190.degree. C. and maintained 
thereat until the evolution of ammonia ceased. A very viscous clear yellow 
aminopolyamide-polyureylene having an I.V. of 0.206 resulted and was 
poured into an aluminum pan. The above procedure was repeated three times 
and the products were combined. 
Part B 
The combined products of Part A (3313 grams), 3806 ml of water and 1780.4 
grams of 37% aqueous HCl were thoroughly mixed to provide a 45.2% aqueous 
solution of the resulting salt, the pH of the solution being 2.8. 
Examination by C.sub.13 NMR indicated that the product contained 63.7 mole 
% oxamide moieties. The resulting salt had an I.V. of 0.171. A portion 
(1366.5 grams) of the salt solution and 2096 ml of water were placed in a 
reaction vessel and the pH of the solution was adjusted to 9.0 with 366.0 
grams of 20% aqueous NaOH. Epichlorohydrin (343.4 grams, 3.17 moles) was 
added, the temperature of the resulting solution was raised to 50.degree. 
C. and the viscosity of the solution was monitored. When the 
Spence-Spurlin viscosity reached 30 seconds, the pH was adjusted to 0.4 
with 37% aqueous HCl. Periodic pH adjustments were made until a pH of 2 
was constant for 1 hour. Five additional portions of the salt solution 
were reacted with epichlorohydrin, as above, and the resulting solutions 
combined to give a composite solution having a total solids content of 
17.4% by weight, a Gardner-Holdt viscosity of B+, and a Brookfield 
viscosity of 31.3 cps. Examination of the composite product by C.sub.13 
NMR indicated that 95.8 mole % of the tertiary amine groups were 
quaternized. 
EXAMPLES 13 TO 15 
The composite resin solution of Example 12 was activated for use using the 
procedure set forth in Examples 3 and 4 and paper sheets were prepared 
using the resulting solution and the mixture of bleached kraft pulp of 
Examples 3 and 4 (Example 13), Chesapeake unbleached kraft pulp (Example 
14) or Manitoba unbleached kraft pulp (Example 15). Strength properties of 
the sheets are set forth in Table IV below. 
TABLE IV 
______________________________________ 
% of Tensile Strength (lbs/inch) 
Ex. Resin Basis Dry Wet 
No. Added Weight Uncured 
Cured Uncured 
Cured 
______________________________________ 
13 0.25 39.6 22.2 23.0 4.10 4.50 
0.50 40.1 23.6 22.7 5.05 5.55 
0.75 39.7 22.7 23.5 5.45 6.06 
Blank -- 39.5 17.9 18.2 0.55 0.49 
14 0.25 39.9 26.2 25.7 4.57 4.64 
0.50 39.7 25.7 25.7 5.53 6.16 
0.75 40.1 26.8 28.9 6.75 7.24 
Blank -- 41.1 21.7 21.8 0.68 0.67 
15 0.25 40.0 23.2.sup.(1) 
23.4 4.47.sup.(1) 
4.79 
0.50 40.0 25.6.sup.(1) 
27.1 6.11.sup.(1) 
6.90 
Blank -- 41.3 23.7 23.3 0.71 0.72 
______________________________________ 
.sup.(1) after 10 days of natural aging. 
Samples of the uncured sheets containing 0.25% resin (based on dry weight 
of the pulp) of Examples 13 to 15 were aged naturally for extended periods 
of time and then repulped according to the procedure of Examples 9 to 11. 
The test results are set forth in Table V below. 
TABLE V 
______________________________________ 
Sheet Days of 
of Ex. 
Natural Degree of Repulping (after minutes) 
No. Aging 5 10 20 30 40 50 60 
______________________________________ 
13 14 &lt;1 2 4 5 6 
14 14 &lt;1 &lt;1 1 2 3 3 4 
15 35 &lt;1 2 4 5 5 6 
______________________________________ 
EXAMPLE 16 
Part A 
Methylbisaminoproplyamine (290.6 grams, 2.0 moles) and 50 ml of water were 
charged to a resin kettle equipped with stirrer, thermometer, heating 
mantle, nitrogen sparge and water trap with condenser and the charge was 
heated to 124.degree. C. Oxalic acid dihydrate (201.7 grams, 1.6 moles) 
was dissolved in 160 ml of water at 70.degree.-80.degree. C. and the 
oxalic acid solution was added dropwise to the kettle over a period of 35 
minutes. After completion of the addition, the temperature was raised to 
185.degree. C. over a period of 1.2 hours and maintained thereat until the 
water was removed. The temperature of the reaction mass was next decreased 
to 155.degree. C. and urea (24.0 grams, 0.4 mole) as a warm (60.degree. 
C.) 50% aqueous solution was added dropwise while maintaining the reaction 
mixture at 155.degree.-158.degree. C. After completion of the urea 
addition the temperature of the mixture was gradually raised to 
185.degree. C. and maintained thereat until the evolution of ammonia 
ceased. Part of the resulting molten aminopolyamide-polyureylene product 
was isolated as the neat free amine and had an I.V. of 0.206. The 
remaining portion of the product was converted to its ammonium chloride 
salt by adding 143.4 grams of 37.9% aqueous HCl and 400 ml of water and 
agitating the mixture thoroughly at 90.degree. C. to provide an aqueous 
solution of the resulting salt. A clear yellow solution having a pH of 
4.0, a solids content of 40.6% and a Brookfield viscosity of 70.3 cps at 
25.degree. C. was obtained. The salt had an I.V. of 0.181. 
Part B 
226.9 grams of the solution of Part A and 188.2 ml of water were charged to 
a reaction vessel and the charge was adjusted to a pH of 8.65 with 32 
grams of 20% aqueous NaOH. Epichlorohydrin (46.3 grams, 0.5 mole) was 
added quickly giving 30% reaction solids, and the temperature was raised 
to 50.degree. C. and the viscosity of the solution was monitored. When the 
Spence-Spurlin viscosity reached 50 seconds, the pH was adjusted to 0.6 
with 17.9 grams of 37.9% aqueous HCl. The temperature was increased to 
60.degree. C. and periodic pH adjustments were made until a pH of 2 was 
constant for about 30 minutes. The resulting solution had a total solids 
content of 22.7% by weight, a Gardner-Holdt viscosity of E at 25.degree. 
C. and a Brookfield viscosity of 92.6 cps at 25.degree. C. 
EXAMPLE 17 
Part A 
The procedure of Example 16, Part A was repeated except that 226.9 grams 
(1.8 moles) of oxalic acid dihydrate and 12.0 grams (0.2 mole) of urea 
were used. The resulting molten aminopolyamide-polyureylene isolated as 
the neat free amine had an I.V. of 0.101, and the aqueous solution of its 
HCl salt had a pH of 4.3, a solids content of 44.3%, a Brookfield 
viscosity of 36.5 cps at 25.degree. C. and an I.V. of 0.086. 
Part B 
213.2 grams of the solution of Part A and 209.5 ml of water were charged to 
a reaction vessel and the charge was adjusted to a pH of 8.50 with 48 
grams of 20% aqueous NaOH. Epichlorohydrin (46.3 grams, 0.5 mole) was 
added quickly giving 30% reaction solids. The temperature of the reaction 
mixture was raised to 65.degree. C. and the viscosity of the solution was 
monitored. When the Spence-Spurlin viscosity reached 32 seconds, the pH 
was adjusted to 0.3 with 37.9% aqueous HCl. The temperature was maintained 
at 65.degree. C. for an additional 3 hours and periodic pH adjustments 
were made with 20% aqueous NaOH to provide a product solution having a pH 
of 1.8. The resulting solution had a total solids content of 22.8% by 
weight, a Gardner-Holdt viscosity of C and a Brookfield viscosity of 50.3 
cps at 25.degree. C. 
EXAMPLES 18 AND 19 
The resin solutions of Examples 16 and 17 were activated for use using the 
procedure set forth in Examples 3 and 4, and paper sheets were prepared 
using the resulting solutions and tested in accordance with the procedure 
of Examples 3 and 4. Strength properties of the sheets are set forth in 
Table VI below. 
TABLE VI 
______________________________________ 
Ad- 
di- Tensile Strength (lbs/inch) 
tion Dry Wet 
Ex. Resin % of Basis Un- Un- 
No. of pulp Weight 
cured Cured cured Cured 
______________________________________ 
18 Ex. 16 0.25 40.3 22.0 22.5 3.53 4.48 
0.50 40.3 22.7 22.9 4.46 5.46 
0.75 39.5 22.1 22.8 5.04 5.97 
19 Ex. 17 0.25 40.4 19.6 20.5 2.41 2.87 
0.50 39.7 21.3 21.5 3.28 3.66 
0.75 40.6 21.5 23.0 4.00 5.23 
Blank -- 40.0 20.1 20.1 0.62 0.63 
______________________________________ 
The uncured sheets containing 0.25% resin (based on dry weight of the pulp) 
were repulped according to the procedure of Examples 9 to 11. The test 
results are set forth in Table VII below. 
TABLE VII 
______________________________________ 
Ex. Degree of Repulping (after minutes) 
No. 5 10 20 
______________________________________ 
18 2 5 6 
19 5 6 
______________________________________