 |
Description  |
|
|
BACKGROUND OF THE INVENTION
This invention relates to the products obtained by reacting a polyamine
salt with an epihalohydrin. Such products are widely used as additives to
improve the wet and dry strength of paper products. More particularly, the
invention describes an improved process by which such additives may be
obtained with greater efficiency.
DISCUSSION OF THE PRIOR ART
U.S. Pat. No. 3,700,623 describes a water-soluble resinous reaction product
of (A) a linear polymer comprising units of the formula
##STR1##
where R is a hydrogen or lower alkyl, and R' is hydrogen, alkyl or a
substituted alkyl group wherein the substituent is a group which will not
interfere with polymerization through a vinyl double bond and is selected
from the group consisting of carboxylate, cyano, ether, amino, amide,
hydrazide and hydroxyl groups and (B) from about 0.5 to about 1.5 moles of
an epihalohydrin per mole of secondary plus tertiary amine present in said
polymer, said product being formed at a temperature of from about
30.degree. to about 80.degree. C. and a pH of from about 7 to about 9.5.
Two divisional applications claiming the above U.S. patent as the parent
were issued as U.S. Pat. Nos. 3,833,531 and 3,840,504. These claim
respectively, a process for making the product claimed in U.S. Pat. No.
3,700,623 and a specified amine copolymer/epihalohydrin reaction product.
The basic process claimed in U.S. Pat. No. 3,833,531 comprises
(1) reacting in aqueous solution
(a) a linear polymer wherein from 5 to 100% of the recurring units have the
formula
##STR2##
where R is hydrogen or lower alkyl and R' is alkyl or a substituted alkyl
group wherein the substituent is a group which will not interfere with
polymerization through a vinyl double bond and is selected from the group
consisting of carboxylate, cyano, ether, amino, amide, hydrazide and
hydroxyl groups with (b) from about 0.5 to about 1.5 moles of an
epihalohydrin per mole of secondary plus tertiary amine present in said
polymer at a temperature of about 30.degree. to about 80.degree. C. and a
pH from about 7 to about 9.5 to form a water-soluble resinous reaction
product containing epoxide groups; and then
(2) reacting the resinous reaction product, in aqueous solution, with from
about 0.3 equivalent to about 1.2 equivalent per equivalent of
epihalohydrin of a water-soluble acid selected from the group consisting
of hydrogen halide acids, sulfuric acid, nitric acid, phosphoric acid,
formic acid and acetic acid until the epoxide groups are converted
substantially to the corresponding halohydrin group and an acid-stabilized
resin solution is obtained.
The polyamine which is reacted with the epichlorohydrin in the process
described in the above patent is prepared by polymerizing the hydrohalide
salt of a diallylamine having the formula
(CH.sub.2 .dbd.C (R)--CH.sub.2).sub.2 N R',
wherein each R is independently selected from the group consisting of
hydrogen and lower alkyl groups and R' is hydrogen, or an alkyl or
substituted alkyl group, either alone or as a mixture with other
copolymerizable monomers in the presence of a free radical catalyst and
then neutralizing the salt to give the polymer free base.
It has now been found that the manner in which this polyamine is prepared
has a very significant effect on the properties and efficacy of the final
product as a wet strength resin and the efficiency of the reaction by
which the final product is obtained.
STATEMENT OF THE INVENTION
The present invention describes a process for the production of an acid
stabilized resin solution which process comprises
(A) polymerizing an aqueous solution of a diallyl amine salt having the
formula [(CH.sub.2 .dbd.C (R)--CH.sub.2).sub.2 NHR'.sym.].sub.n X.sup. ;
wherein the R groups are the same or different and are selected from
hydrogen and lower alkyl groups, R' is selected from hydrogen, alkyl and
substituted alkyl groups and X.sup. is an anion other than a halide anion
derived from an acid in which the final pKa is less than 2 and n is an
integer from 1 to 3 and is the valence of the anion; either alone or as a
mixture with other copolymerizable monomers, in the presence of a free
radical catalyst to form a polymer in which from 5 to 100% of the
recurring units are derived from the diallylamine:
(B) raising the pH of the solution sufficiently to convert part or all of
the monomeric and polymeric amine salt functionalities to free amine
groups but not so high as to precipitate the polyamine from solution;
(C) reacting the polyamine with from about 0.5 to about 1.5 mole of an
epihalohydrin per mole equivalent of secondary plus tertiary amine present
in said solution, at a temperature of about 30.degree. to about 80.degree.
C. and a pH from about 7 to about 9.5, to form a water-soluble resinous
reaction product containing epoxide groups; and
(D) reacting the resinous reaction product in aqueous solution, with from
about 0.3 equivalents to about 1.2 equivalents per equivalent of
epihalohydrin of a watersoluble acid selected from the group consisting of
hydrogen halide acids, sulfuric acid, nitric acid, phosphoric acid, formic
acid and acetic acid until an acid-stabilized resin solution is obtained.
Conventionally the polyamine is produced by the polymerization of the
diallylamine in the presence of a hydrohalide acid and after the formation
of the polymer is complete, the pH is raised to liberate the polyamine
which is then reacted with an epihalohydrin. Thus, the reaction mixture
contains a large amount of halide ion associated with the polyamine halide
salt.
It has now been found that the epihalohydrin reacts with such halide ion in
accordance with the following reaction:
##STR3##
where X.sub.1 and X.sub.2 are the same or different halogen atoms.
Thus, epihalohydrin is removed from the reaction mixture as dihalopropanol
and is thus unable to react with the polyamine. The dihalopropanol itself
it much less reactive towards amines than is the epihalohydrin. This
competing reaction is therefore, a serious limitation on the efficiency
with which the expensive epihalohydrin can be used in the formation of the
final polymeric adduct.
Up till now the most effective way to overcome this defect was to separate
the polyamine from the halidecontaining reaction mixture in which it was
formed as is disclosed in U.S. application Ser. No. 685,227, filed Mar. 1,
1978, but this of course involves the expense of introducing an extra step
into the production sequence and this is not generally a favored
alternative.
It has now been found that substantially the same results can be obtained
by forming the polyamine in the presence of a strong non-hydrohalide acid
having a final pKa of not more than 2, such as sulphuric acid (second pKa
1.92), nitric acid (pKa 1.34), perchloric acid (pKa 0.73), trichloroacetic
acid (pKa 0.64), benzene sulfonic acid (pKa 0.70) and the like. This is
based on the unexpected discovery that the reaction of anions derived from
such acids with epihalohydrins is very much slower than the reaction of
halide ions with epihalohydrins. Thus, the extent to which the
epihalohydrin reactant is removed from the reaction to form an essentially
useless by-product is greatly reduced.
The term "final pKa" is used to indicate the pKa at which the ionization of
the acid anion is complete. Thus, for phosphoric acid it is the pKa at
which the third acid hydrogen proton is removed (12.36) and for sulphuric
acid it is the pKa at which the bisulfate ion becomes the sulfate ion
(1.92).
It should be noted that phosphoric and oxalic acids are excellent in amine
salt polymerization and in epichlorohydrination--but seriously interfere
in one or more aspects of wet strength development such as retention on
pulp fibers and thermoset curing.
The wide pKa separations associated with differing H.sup.+ ionization
constants in such acids as H.sub.3 PO.sub.4, H.sub.2 C.sub.2 O.sub.4, etc.
is believed to cause the observed buffering action occurring during
deliberate pH change and is characteristic of association reactions
between amine (basic) and acid (acidic) groups comprising the salt.
Particularly preferred on account of their cheapness and the extreme
slowness of their reaction with epihalohydrins are the nitrate ion and the
sulfate ion and derived species such as the bisulfate ion.
It is also surprisingly found that the use of an amine salt other than the
hydrohalide markedly speeds up the polymerization rate, that is, the rate
at which the polyamine is formed. It is speculated that this may reflect
the greater ability of the halide ion to act as a chain transfer agent and
as a chain terminator. Whatever the cause, it is found that the conversion
of monomer to polymer is substantially greater at a given point in time
when the amine salt polymerized is a salt of a strong acid other than
hydrohalide acid.
Specific non-halide salts of the diallylamines which can be polymerized to
provide the polymer units of the invention include the sulphates,
bisulphates, nitrates, perchlorates, trichloroacetates, and sulfonates of
diallylamine, N-methyldiallylamine, 2,2'-dimethyl-N-methyldiallylamine,
N-ethyldiallylamine, N-isopropyldiallylamine, N-n-butyldiallylamine,
N-tert-butyldiallylamine, N-n-hexyldiallylamine, N-octadecyldiallylamine,
N-acetamidodiallylamine, N-cyanomethyldiallylamine,
N-.beta.-propionamidodiallylamine, N-acetic ethyl ester substituted
diallylamine, N-ethylmethylether substituted diallylamine,
N-.beta.-ethylaminodiallylamine, N-hydroxyethyldiallylamine and
N-aceto-hydroazide substituted diallylamine.
Diallylamines and N-alkyldiallylamines, used to prepare the polymers
employed in this invention, can be prepared by the reaction of ammonia or
a primary amine with an allyl halide employing as a catalyst for the
reaction a catalyst that promotes the ionization of the halide such, for
example, as sodium iodide, zinc iodide, ammonium iodide, cupric bromide,
ferric chloride, ferric bromide, zinc chloride, mercuric iodide, mercuric
nitrate, mercuric bromide, mercuric chloride, and mixtures of two or more.
Thus, for example, N-methyldiallylamine, in good yield, can be prepared by
reaction of two moles of an allyl halide, such as allyl chloride, with one
mole of methylamine in the presence of an ionization catalyst such as one
of those enumerated above. To avoid the need to regenerate the amine from
the salt product before polymerization, it is possible to use a non-halide
allyl salt during the amine formation but such reactions often do not
readily and easily occur and this technique is less preferred in general.
In preparing the homopolymers and copolymers for use in this invention,
reaction can be initiated by redox catalytic system. In a redox system,
the catalyst is activated by means of a reducing agent which produces free
radicals without the use of heat. Reducing agents commonly used are sodium
metabisulfite and potassium metabisulfite. Other reducing agents include
water-soluble thiosulfates and sulfites, hydrosulfites and reducing salts
such as the sulfate of a metal which is capable of existing in more than
one valence state such as cobalt, iron, manganese and copper. A specified
example of such a sulfate is ferrous sulfate. The use of a redox initiator
system has several advantages, the most important of which is efficient
polymerization at lower temperatures. Conventional peroxide catalysts such
as tertiarybutyl hydroperoxide, potassium persulfate, hydrogen peroxide,
and ammonium persulfate used in conjunction with the above reducing agents
or metal activators, can be employed.
As stated above, the linear polymers of diallylamines which are reacted
with an epihalohydrin in accordance with this invention can contain
different diallylamine units and/or contain units of one or more other
copolymerizable monomers. Typically, the comonomer is a different
diallylamine, a monoethylenically unsaturated compound containing a single
vinylidene group or sulfur dioxide, and is present in an amount ranging
from 0 to 95 mole percent of the polymer. Thus, the polymers of
diallylamine are linear polymers wherein from 5 to 100% of the recurring
units are monomer units derived from (1) a vinylidene monomer and/or (2)
sulfur dioxide. Preferred comonomers include acrylic acid, methacrylic
acid, methyl and other alkyl acrylates and methacrylates, acrylamide,
methacrylamide, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl
ethers such as the alkyl vinyl ethers, vinyl ketones, such as methyl vinyl
ketone and ethyl vinyl ketone, vinyl sulfonamide, sulfur dioxide or a
different diallylamine.
Specific copolymers which can be reacted with an epihalohydrin include
copolymers of N-methyldiallylamine and sulfur dioxide copolymers of
N-methyldiallylamine and diallylamine; copolymers of diallylamine and
acrylamide, copolymers of diallylamine and acrylic acid; copolymers of
N-methyldiallylamine and methyl acrylate; copolymers of diallylamine and
acrylonitrile; copolymers of N-methyldiallylamine and vinyl acetate;
copolymers of diallylamine and methyl vinyl ether; copolymers of
N-methyldiallylamine and vinylsulfonamide; copolymers of
N-methyldiallylamine and methyl vinyl ketone; terpolymers of diallylamine,
sulfur dioxide and acrylamide; and terpolymers of N-methyldiallylamine,
acrylic acid and acrylamide.
The epihalohydrin which is reacted with the polymer of a diallylamine can
be any epihalohydrin, i.e., epichlorohydrin, epibromohydrin,
epifluorohydrin, or epiidohydrin and is preferably epichlorohydrin. In
general, the epihalohydrin is used in an amount ranging from about 0.5
mole to about 1.5 moles and preferably about 1 mole to about 1.5 moles per
mole of secondary plus tertiary amine present in the polymer.
The resinous reaction products of the invention can be prepared by reacting
a homopolymer or copolymer of a diallylamine as set forth above with an
epihalohydrin at a temperature of from about 30.degree. C. to about
80.degree. C., and preferably from about 40.degree. C. to about 60.degree.
C. until the viscosity measured on a solution containing 20% to 30% solids
at 25.degree. C. has reached a range of A to E and preferably about C to D
on the Gardner-Holt scale. The reaction is preferably carried out in
aqueous solution to moderate the reaction, and at a pH of from about 7 to
about 9.5. When the desired viscosity is reached, sufficient water is
added to adjust the solids content of the resin solution to about 15% or
less and the product cooled to room temperature (about 25.degree. C.). The
resin solution obtained is then stabilized by adjusting to a pH of at
least about 6 and preferably to a pH of below about 5. Any suitable acid
such as hydrochloric, sulfuric, nitric, formic, phosphoric and acetic acid
can be used to adjust the pH.
The aqueous resin solutions can be applied to paper or other felted
cellulosic products by tub application or by spraying, if desired. Thus,
for example, preformed and partially or completely dried paper can be
impregnated by immersion in, or spraying with, an aqueous solution of the
resin, following which the paper can be heated for about 0.5 minute to 30
minutes at temperatures of 90.degree. C. to 100.degree. C. or higher to
dry same and cure the resin to a water-insoluble condition. The resulting
paper has greatly increased wet and dry strength, and therefore this
method is well suited for the impregnation of paper such as wrapping
paper, bag paper and the like, to impart both wet and dry strength
characteristics thereto.
The preferred method of incorporating these resins in paper, however, is by
internal addition prior to sheet formation, whereby advantage is taken of
the substantivity of the resins for hydrated cellulose fibers. In
practicing this method, an aqueous solution of the resin in its uncured
and hydrophilic state is added to an aqueous suspension of paper stock in
the beater, stock chest, Jordan engine, fan pump, head box or at any other
suitable point ahead of sheet formation. The sheet is then formed and
dried in the usual manner.
The "off-the-machine" wet strength obtained with the resins of the
invention will be satisfactory for most applications. Additional wet
strength can be obtained by subjecting the paper to a heat treatment.
Satisfactory temperatures will be of the order of from about 105.degree.
C. to about 150.degree. C. for a period of time from about 12 to 60
minutes, time varying inversely with temperature.
While the reaction products herein described impart substantial wet
strength to paper they also improve the dry strength of paper when present
in relatively small amounts. The reaction products obtained by the process
of the invention can be added to a fibrous cellulosic substrate such as
paper in amounts that can range up to 15 kilos per metric ton of
substrate. Generally, the levels of addition in commercial operations is
from 1 to 10 and especially from 2 to 8 kilos per metric ton.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following Examples are illustrative of the invention only and are not
intended to imply any limitation or restriction thereof.
Example 1 describes the test method used to evaluate acids which may be
used to form the amine salts before polymerization. The other Examples
describe the production of polyamine adducts and the performance of such
adducts as wet strength additives when applied to cellulosic substrates.
EXAMPLE 1
The fundamental discovery underlying this invention is that halide ions
react much more rapidly with epihalohydrin than do anions derived from
other strong acids. This Example describes a method by which the various
anions can be compared under readily reproducible conditions. It is based
on the fact that the reaction between the epihalohydrin and the anion
releases hydroxyl ions which therefore raise the pH of the reaction
mixture. The extent to which the pH rises is therefore an indication of
the extent of the reaction; the rapidity with which the pH rises is
indicative of the rate of the forward reaction.
Saturated solutions in deionized water at 25.degree. C. of the sodium salts
of each of the anions to be evaluated were prepared and 20 ml. of each
solution were added to separate vials and 0.067 gram of AR epichlorohydrin
was added to each. Each vial was capped and shaken vigorously. The pH of
each was taken at the indicated time intervals. The results are set forth
in Table 1.
TABLE 1
______________________________________
pH at indicated time
Salt Solution 0 sec. 10 sec. 10 min.
18 hrs.
______________________________________
Sodium chloride
6.41 9.05 -- 9.33
Sodium sulfate
6.35 6.37 6.58 7.71
______________________________________
The very rapid increase in pH shown by the sodium chloride
solution/epichlorohydrin mixture is indicative of the extent of the
interference of this reaction with the polyamine/epihalohydrin reaction in
the process of the prior art. Conversely, the non-halide salts show a very
much slower byproduct reaction.
EXAMPLE 2
This Example describes the production of a wet-strength resin by the
process of the invention.
A flask was fitted with an addition funnel, a thermometer, a stirrer and a
nitrogen inlet tube. The flask was charged with 222.4 grams (2.0 moles) of
flash-distilled N-methyldiallylamine and 200 ml. of deionized water. To
the flask were added 204.1 grams of 50% by weight aqueous solution of 96%
sulfuric acid. The addition was done at 10.degree.-15.degree. C. After all
the acid had been added 14.3 grams of deionized water were added along
with 1-2 drops of 96% sulfuric acid to adjust the pH to 3.5. The flask and
contents were then nitrogen purged to remove air.
To this amine salt solution were added 10.0 grams of 50% aqueous ammonium
persulfate solution and while blanketing with nitrogen throughout, the
temperature was raised to 50.degree. C. The reaction became strongly
exothermic and for a brief period, after about 90 minutes, the temperature
rose to 90.degree. C. before being controlled and reduced to 60.degree. C.
where it remained for the rest of the polymerization. After two hours, the
solution had become very viscous and orange in color. A further 4.00 grams
of the 50% ammonium persulfate solution were added to finish off the
reaction. After six hours of stirring under a nitrogen blanket the
reaction was shut down and a viscous organic resin solution remained.
Analysis of this solution showed that a conversion (monomer to polymer) of
96.8% had been achieved.
A charge of 43.3 grams (0.10 monomer unit equivalent) of the
poly(N-methyldiallylamine)sulphate salt prepared above was placed in a
flask and 65.4 grams of water and 4.50 grams of 10% aqueous sodium
hydroxide were added to raise the pH to 8.42. The temperature of the
mixture was 10.degree. C.
The dropwise addition of 9.25 grams (0.10 mole) of epichlorohydrin to the
stirred polyamine was begun. The stirred reaction mixture was initially
maintained at 10.degree. C. for 15 minutes after which the temperature was
allowed to rise to 50.degree. C. During the reaction at 50.degree. C.
until the time the reaction was killed, the mixture became more viscous
and the pH slowly dropped. A total of 20 equiv. % of 10% sodium hydroxide
was added incrementally to maintain the reaction pH above 7.
After 200 minutes the reaction was killed by addition of 0.80 gram of 96%
sulphuric acid with stirring and cooling.
The resulting polymer adduct had a Gardner viscosity of E.sup.- and a pH at
25.degree. C. of 2.31.
Two further polymeric adducts according to the invention were prepared by
essentially the same process as is set forth above in Example 2. For
purposes of comparison a polymeric adduct was prepared according to the
prior art, i.e., using the hydrochloride salt of the amine produced by an
otherwise similar method. The results obtained are set forth in Table II
below.
TABLE II
__________________________________________________________________________
SUMMARY OF EXAMPLES 2-4
EPIHALOHYDRIN POLYMERIC ADDUCT
Polymer Adduct
Ratio Added
pH at
% Gardner
Resin
Epi %
Example
Identification
E/A.sup.(1)
NaOH.sup.(2)
25.degree. C.
Solids
Viscosity
Yield
Conv.
DCP.sup.(3)
Note
__________________________________________________________________________
2 Poly(N-methyldi-
allylamine.
1.0 0.31 2.31
16.43
E.sup.-
97.9%
96.4%
1.25
A
H.sub.2 SO.sub.4 salt)/Epi
3 Poly(N-methyldi-
allylamine.
0.8 0.26 2.33
16.76
E 99.5%
97.6%
0.96
A
H.sub.2 SO.sub.4 salt)/Epi
4 Poly(N-methyldi-
allylamine/
1.0 0.26 2.85
20.43
N 99.2%
95.8%
1.48
B
diallylamine
H.sub.2 SO.sub.4 salt)/Epi.sup.(4)
Comparative
Poly(N-methyldi-
diallylamine.
0.8 0.26 2.0 15.45
E/E.sup.+
91.4%
91.2%
3.07
C
HCl Salt)-Epi
__________________________________________________________________________
.sup.(1) Ratio of equivalents of epihalohydrin to amine monomer unit
equivalents.
.sup.(2) Equivalents per monomer unit equivalent of amine.
.sup.(3) Weight percent of dichloropropanol in the final reaction mixture
adjusted to 25% by weight of total solids.
.sup.(4) Nmethyldiallylamine/diallylamine are in a 1:1 molar ratio.
A Polyamine obtained in 96.8% conversion from monomer after 6 hours.
(56.4% in 1.0 hour).
B Polyamine obtained in 97.8% conversion from monomers after 6 hours.
C Polyamine obtained in only 84.8% conversion from monomer after 72 hours
Polyamine therefore contained 15.2% of unconverted monomer.
The data given in Table II clearly show that the process of the invention
gives much better results by comparison with the prior art process in
that:
1. the formation of the polymer proceeds much more quickly and reaches a
higher monomer to polymer conversion level;
2. the efficiency with which the epichlorohydrin is incorporated into the
polymeric adduct is greater; and
3. the amount of dichloropropanol by-product obtained is more than halved.
EXAMPLE 5
This example shows the cured and uncured wet tensile strengths obtained
when the polymeric adducts of Examples 2 to 4 are applied to a cellulosic
substrate in the manner described in Example 6 and compares them with the
values obtained using the comparative adduct described in Table II.
The results are set forth in Table III below.
TABLE III
______________________________________
CURED AND UNCURED
WET TENSILE STRENGTHS IN g/cm.
Uncured Cured
Application Level
Application Level
kg/metric ton kg/metric ton
Example 2.5 5.0 7.5 2.5 5.0 7.5
______________________________________
2 430 593 697 523 664 773
3 371 532 629 447 593 670
4 307 416 557 379 500 602
Compara- 384 500 609 447 561 682
tive
______________________________________
This table shows that the effect of changing the salt carries through to
the wet-strengths obtained. This efficiency difference is perhaps
attributable at least in part to the presence of the larger proportion of
unreacted monomer in the polyamine adduct prepared using the polyamine
chloride salt. Note that Example 4 was prepared using an amine copolymer
and therefore, is not strictly comparable with the other data reported in
this table.
EXAMPLE 6
This Example sets forth a comparison of wet strength resins in which the
amine prepolymer is produced (A) in the form of the chloride salt (the
prior art); and (B) in the form of the nitrate salt (the invention).
PRODUCTION OF RESIN (PRIOR ART)
1. Production of Prepolymer
A reaction vessel was charged with 222.4 g (2.0 moles) of flash-distilled
N-methyldiallylamine, 200 g of deionized water and 219.4 g of 36%
concentrated hydrochloric acid. This produced a solution with a pH of 3.5
and an amine hydrochloride salt concentration of 45.0% by weight. The
addition was preformed at 10.degree.-15.degree. C. with the hydrochloric
acid being added dropwise with good stirring and cooling to maintain the
temperature in the above range. The two phase reaction mixture cleared
rapidly as the pH dropped below about 6 to 7. A nitrogen purge was
introduced and the system was left overnight at 0.degree.-22.degree. C.
To the above reaction mixture was added, in one charge, 5.00 g of ammonium
persulfate ("APS") solids in the form of 11.5 g of a 45% aqueous solution.
The nitrogen purge was continued while the reaction vessel was heated to
50.degree. C., with continued stirring, over a period of 30 minutes.
At about 45.degree. C. the reaction became exothermic and air jet cooling
was initiated to maintain the temperature at about 50.degree. C. At 0.75
hr. an increase in viscosity was noted and at 2.5 hrs. the exotherm
subsided and gentle heating was initiated to maintain the reaction
temperature. The reaction was continued under nitrogen, with stirring, at
50.degree. C. for a further 21/2 days after which a solution containing
44.85% total solids, (44.10% in terms of monomer-derived solids), having a
pH of 1.52 and a Gardner viscosity of E/E.sup.+ was obtained. The process
is summarized in Table IV.
2. Preparation Wet/Dry Strength Resin
A reaction vessel was charged with 33.37 g (0.10 amine monomer unit
equivalents) of the amine prepolymer solution prepared above. The total
solids charged (theory) was 14.966 g. In addition 4.50 g. (0.01125
equivalent) of a 10% aqueous sodium hydroxide solution and 67.86 g. of
water were charged into the vessel. The resultant pH was 8.35
The reaction commenced at 10.degree. C. when 7.40 g. (0.08 mole) of
epichlorohydrin was added over a 1 minute period with stirring. Over the
next hour the temperature rose to 50.degree. C., the solution first became
turbid and then cleared and the pH dropped to below 7.80.
At intervals during the reaction dropwise additions of 2.0 g. amounts of
10% aqueous sodium hydroxide were made to maintain the pH above 7.
After a little more than three hours the Gardner viscosity had risen to F/G
and the reaction was killed, (i.e. short-stopped) by addition of 0.50 g.
of 96% sulphuric acid with continued stirring and cooling.
The properties of the final solution are set forth in detail in Table V
below.
Production of Resin B (Illustrative of the Invention)
1. Production of the Prepolymer
A reaction vessel was charged with 111.18 g. (1.00 mole) of
N-methyldiallylamine, 90.0 g. (1.00 equivalent of hydrogen ion) of 70% AR
nitric acid and 147.18 g. of deionized water. The initial pH at 25.degree.
C. was 4.55.
This amine salt solution was then polymerized using a solution of 2.25 g.
of AR ammonium persulfate in 2.25 g. of deionized water at a temperature
of 60.degree. C.
The formation of the amine salt and the polymerization technique followed
substantially the same procedures as were outlined in the corresponding
description of the preparation of Resin A with the difference that the
polymerization reaction was complete after 10 hours. The process is
summarized in Table IV.
The Gardner viscosity of the prepolymer after adjustment to 45% total
solids by addition of water was E/E.sup.+ and the pH at 25.degree. C. was
1.34.
2. Reaction with Epichlorohydrin
A reaction vessel was charged with 39.21 g. (0.100 amine monomer unit
equivalent) of the amine prepolymer salt produced as described above. To
the same vessel were added 75.6 g. of deionized water and 4.50 g. (0.01125
equivalent) of 10% aqueous sodium hydroxide solution. This solution then
was clear and had a pH of 8.37.
The reaction was begun by addition of 7.40 g. (0.08 mole) of
epichlorohydrin over a 1 minute period to the above reaction mixture at
10.degree. C. The reaction was continued in the manner described above in
relation to the preparation of Polymer A.
The properties of the final Polymer B are set forth in Table V below.
TABLE IV
______________________________________
POLY(AMINE SALT) SYNTHESES
Polymer Salt Prepared
Poly(N-methyldi-
Poly(N-methyldi-
allylamine allylamine
HCl Salt) HNO.sub.3 Salt)
______________________________________
Reaction Parameters and
Conditions Employed .sup.(1)
Amine Salt Charged Moles
2.00 1.00
(NH.sub.4).sub.2 S.sub.2 O.sub.8 g/amine salt,
5.00 2.25
moles
Temp. C..degree./
Time, Hrs. 50.degree. C./72 hrs.
60.degree. C./10 hrs.
Run Conc. % 45% 50%
M/P Conversion, % .sup.(2)
84.8% 93.1%
Aqueous Poly(Amine Salt)
Solution Properties
Solution Conc. %
44.85% 45.10%
Gardner Viscosity
E/E.sup.+ E/E.sup.+
Solution pH 1.52 1.34
Monomer Unit Equiv.
Wt., gms. .sup.(3)
333.65 g. 392.07 g.
______________________________________
.sup.(1) Stirred 4necked round bottomed flask, N.sub.2 blanketed
throughout.
.sup.(2) Determined gravimetrically, via double precipitation of resin
from A.R. acetone.
.sup.(3) Grams aqueous resin solution obtained divided by amine salt mole
(equivalents) charged.
TABLE V
______________________________________
EPICHLOROHYDRINATIONS OF POLY(AMINE SALTS)
Polymer Salt Employed
Poly(N-methyldi-
Poly(N-methyldi-
allylamine allylamine
HCl Salt) HNO.sub.3 Salt)
(Polymer A)
(Polymer B)
______________________________________
Reaction Parameters and
Conditions Employed
NaOH, Eq. % (1)
22.5 25.0
pH Range at .degree.C.
8.35-7.11 8.37-6.31
E/A (2) 0.80 0.80
Conc., % 20% 20%
Temp. C.degree. (3)
10.degree. C..fwdarw.
10.degree. C..fwdarw.
50.degree. C.
50.degree. C.
`Kill` Viscosity
Gardner (4) F/G H
Reaction Time. Hrs.
3:05 3:30
Resin (EPI Adduct)
Solution Properties
Resin Yield % (5)
91.0% 101.3%
Conc., % 15.39% 17.34%
Gardner Viscosity (4)
D.sup.+ /E.sup.-
E.sup.+ /F.sup.-
Solution pH 2.00 2.07
% DCP at T.S. found (6)
2.04% 0.72%
EPI Conv., % (7)
61.9% 89.3%
______________________________________
(1) An initial addition of 11.25 equivalent % of 10% NaOH raised the
solution pH from 1.5 to 8.3-8.4; thereafter, incremental addition was
maintained as needed to build solution viscosity.
(2) Moles epi/amine monomer unit equivalent charged.
(3) Initial 10.degree. C. temp.; gradual rise to viscosity building temp.
to 50.degree. C.
(4) at room temperature.
(5) (Determined solids/theoretical solids) .times. 100.
(6) Via G.L.C. analysis resin solution.
(7) Based on determination of DCP (dichloropropanol).
EPI Conversion (%) = 100 -?
##STR4##
##STR5##
PREPARATION OF PAPER
A pulp of 50/50 bleached softwood and hardwood Kraft with Canadian Standard
Freeness of about 450 and a pH of 7.0 was treated with the appropriate
amount of resin and the treated pulp was made into a 8 inch square
handsheet. The press consistency was 36.1% and the paper sheet was dried
at 95.degree. C. to a moisture level of 4.1% using a drum rotation speed
of 2 minutes per revolution.
To measured aliquot samples of the above pulp slurry were added, with
stirring, measured amounts of the appropriate resin. Prior to addition to
the pulp slurry the polymers were activated by the addition, over several
seconds, of 7.0 meq. of 25% aqueous sodium hydroxide per gram of resin
solids; the resin concentration was pre-adjusted to 3.0% solids with
deionized water. The activated mixture was stirred throughout the NaOH
addition and then for 1.0 minute at room temperature before being finally
diluted to 1.2% concentration by addition of more deionized water.
WET STRENGTH TESTING
The wet tensile strengths of Polymers A and B are compared in Table VI. The
cured samples had been subjected to heating at 90.degree. C. for 15
minutes. The uncured samples were tested straight from the
paper-production operation. Both were wetted before testing on an Instron
Tensile Tester.
TABLE VI
______________________________________
WET STRENGTH OF PAPERS TESTED
POLYMERS A AND B
AT DIFFERENT ADDITION LEVELS
Addition Uncured Tensile
Cured Tensile
Level in Strength in Strength in
Kg/metric g/cm (Average g/cm (Average
Polymer ton of 4) of 4)
______________________________________
A (Prior Art)
2.5 329 482
5.0 443 666
7.5 518 747
B (Invention)
2.5 411 639
5.0 529 830
7.5 647 1023
______________________________________
From this it can be seen that the wet tensile strength of the Polymer B
produced using the nitrate salt is very much more effective than that
produced using the chloride salt.
Moreover, comparison of the results in Tables IV and V shows that it is
produced very much more efficiently with fewer by-products.
The above Examples are for illustration only and are not intended to imply
any limitation of the invention. It will be appreciated that many minor
variations and additions might be made without changing the essential
nature of the invention. It is intended that all such variations and
additions shall be embraced within the purview of this invention.
* * * * *
|
|
 |
|
 |
Description |
|
