Polyalkyldiallylamine-epihalohydrin resins as wet strength additives for papermaking and process for making the same
View Patent ↗The present invention relates to a process for making polyalkyldiallylamine-epihalohydrin resins, the resultant resins and their uses as wet strength additives for papermaking. These resins are obtained by a two step process, wherein the first step comprises the free radical polymerization or copolymerization of an alkyldiallylamine monomer in its protonated form; and the second step comprises reacting an ADAA polymer or copolymer with epihalohydrin under carefully controlled reaction conditions.
1. A process for forming a polyalkyldiallylamine-epihalohydrin resin comprising the steps of:
(a) forming an alkyldiallylamine polymer by the free-radical polymerization or copolymerization in a first aqueous solution of a hydrohalide salt of an alkyldiallylamine monomer, said alkyldiallylamine polymer having a reduced specific viscosity less than or equal to about 0.20 dL/g and a residual alkyldiallylamine monomer content of less than about 2.0%; and
(b) reacting the alkyldiallylamine polymer with an epihalohydrin in a second aqueous solution, wherein the ratio of epihalohydrin to alkyldiallylamine polymer amine functionality is from about 0.90 to about 1.10, comprising the steps of:
(i) mixing an epihalohydrin and the alkyldiallylamine polymer at a total solids content of about 10 to 30% and a temperature of about 25 to 45° C., resulting in a reaction mixture;
(ii) simultaneously with step (i), adding an aqueous alkaline solution to the reaction mixture to maintain a pH between about 8.0 and 9.0 over a time period of about 4 to 14 hours;
(iii) adjusting the pH of the reaction mixture to 1.0 to 3.0 with a mineral acid;
(iv) heating the reaction mixture to between 70 to 90° C. for about 0.5 to 3.0 hours; and
(v) simultaneously with step (iv), maintaining the pH of the reaction mixture at 1.0 to 3.0 by the addition of mineral acid.
2. The process according to claim 1 , wherein the alkyldiallylamine monomer is selected from the group consisting of N-methyldiallylamine, N-ethyldiallyamine, N-n-propyldiallylamine, N-isopropyldiallylamine, N-butyldiallylamine, N-tert-butyldiallylamine, N-sec-butyldiallylamine, N-pentyldiallyamine, N-n-hexyldiallyamine, N-acetamidodiallylamine, N-cyanomethyldiallylamine, N-β-propionamidodiallylamine, N-(2-hydroxyethyl)diallylamine and mixtures thereof.
3. The process according to claim 1 , wherein the hydrohalide salt of the alkyldiallylamine monomer is a hydrochloride salt.
4. The process according to claim 3 , wherein the alkyldiallylamine monomer is the hydrochloride salt of N-methyldiallylamine.
5. The process according to claim 1 , wherein the reduced specific viscosity of the alkyldiallylamine polymer is between about 0.05 dL/g and about 0.20 dL/g.
6. The process according to claim 5 , wherein the reduced specific viscosity of the alkyldiallylamine polymer is between about 0.10 dL/g and about 0.20 dL/g.
7. The process according to claim 1 , wherein the residual alkyldiallylamine monomer content is less than about 1.0%.
8. The process according to claim 1 , wherein the alkyldiallylamine polymer is a copolymer of the alkyldiallylamine monomer and a vinyl monomer.
9. The process according to claim 8 , wherein the vinyl monomer is an acrylamide, methacrylamide, acrylic acid, methacrylic acid, itaconic acid or mixtures thereof.
10. The process according to claim 1 , wherein the epihalohydrin is epichlorohydrin.
11. A resin comprising the reaction product of the process according to claim 1 .
12. A cellulose matrix comprising the resin of claim 11 .