# US 2018/0023254 A1 · High efficiency wet strength resins from new cross-linkers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0023254 A1 - Document ID: US20180023254A1 - Status: Published application - Kind: A1 - Application number: 15/722,944 - Filed: 2017-10-02 - Published: 2018-01-25 - Earliest claimed: 2012-07-19 - Assignees: Georgia-Pacific Chemicals LLC - Applicants: Georgia-Pacific Chemicals LLC - Inventors: Clay E. Ringold; Cornel Hagiopol; Dexter C. Johnson - Web page: https://patentgrep.com/patent/US20180023254A1 ## CPC - D21H 21/20: Wet strength agents - C08G 73/06: Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule - D21H 11/04: Kraft or sulfate pulp - D21H 17/33: Synthetic macromolecular compounds - D21H 17/52: Epoxy resins - D21H 17/55: Polyamides; Polyaminoamides; Polyester-amides - D21H 17/56: Polyamines; Polyimines; Polyester-imides - D21H 23/04: Addition to the pulp; After-treatment of added substances in the pulp - D21H: PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR - C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS ## Abstract Compositions and methods related to new wet strength resins are provided. By using functionally-symmetrical cross-linkers and mono-functional modifiers, and separating the steps of reacting a prepolymer with the cross-linkers from the reaction of intermediate cross-linked prepolymer with epichlorohydrin, new wet strength resin products are provided having improved properties. ## Claims ### Claim 1 A strengthening resin comprising a polyamine partially crosslinked with a bridging moiety and having azetidinium ions and a charge density of at least 2.4 mEq/g of solids. ### Claim 2 (depends on 1) The strengthening resin of claim 1, wherein the charge density is about 2.5 mEq/g of solids to about 4 mEq/g of solids, and wherein the bridging moiety is derived from a functionally symmetric cross-linker is selected from: wherein R4 is (CH2)t, wherein t is 1, 2, or 3; wherein x is from 1 to about 100; wherein y is from 1 to about 100; wherein x′+y′ is from 1 to about 100; wherein z is from 1 to about 100; wherein a q/p ratio is from about 10 to about 1000; a copolymer of an acrylate monomer, a methacrylate monomer, an alkene monomer, or a diene monomer, with an azetidinium-functionalized monomer selected from and a combination thereof, wherein the fraction of azetidinium-functionalized monomer to the acrylate monomer, the methacrylate monomer, the alkene monomer, or the diene monomer in the copolymer is from about 0.1% to about 12%; and a combination thereof. ### Claim 3 (depends on 1) The strengthening resin of claim 1, wherein the charge density is about 2.5 mEq/g of solids to about 4 mEq/g of solids, and wherein the bridging moiety is derived from a functionally symmetric cross-linker comprising a di-acrylate compound, a bis(acrylamide) compound, a di-epoxide compound, a polyazetidinium compound, N,N′-methylene-bis-methacrylamide, a poly(alkylene glycol) diglycidyl ether, or any combination thereof. ### Claim 4 (depends on 3) The strengthening resin of claim 3, wherein the functionally symmetric cross-linker comprises the di-acrylate compound. ### Claim 5 (depends on 3) The strengthening resin of claim 3, wherein the functionally symmetric cross-linker comprises the bis(acrylamide) compound. ### Claim 6 (depends on 3) The strengthening resin of claim 3, wherein the functionally symmetric cross-linker comprises the di-epoxide compound. ### Claim 7 (depends on 3) The strengthening resin of claim 3, wherein the functionally symmetric cross-linker comprises the N,N′-methylene-bis-methacrylamide. ### Claim 8 (depends on 3) The strengthening resin of claim 3, wherein the functionally symmetric cross-linker comprises the poly(alkylene glycol) diglycidyl ether. ### Claim 9 (depends on 1) The strengthening resin of claim 1, wherein the polyamine comprises a polyamidoamine. ### Claim 10 (depends on 1) The strengthening resin of claim 1, wherein the azetidinium ions are formed by reacting an epihalohydrin and the polyamine partially crosslinked with the bridging moiety. ### Claim 11 (depends on 1) The strengthening resin of claim 1, wherein the polyamine partially crosslinked with the bridging moiety has an azetidinium equivalent weight of 2,000 to about 3,800. ### Claim 12 (depends on 1) The strengthening resin of claim 1, wherein the polyamine partially crosslinked with the bridging moiety has a weight average molecular weight of 900,000 to about 1,700,000. ### Claim 13 (depends on 1) The strengthening resin of claim 1, wherein the polyamine partially crosslinked with the bridging moiety contains less than 10,000 ppm of 1,3-dichloro-2-propanol. ### Claim 14 (depends on 1) The strengthening resin of claim 1, wherein the polyamine partially crosslinked with the bridging moiety has a charge density of about 2.5 mEq/g of solids to about 3.5 mEq/g of solids, an azetidinium equivalent weight of 2,000 to about 3,500, a weight average molecular weight of 900,000 to about 1,700,000, and contains less than 10,000 ppm of 1,3-dichloro-2-propanol. ### Claim 15 A process for strengthening paper, comprising contacting a plurality of fibers with a strengthening resin comprising a polyamine partially crosslinked with a bridging moiety and having azetidinium ions and a charge density of at least 2.4 mEq/g of solids. ### Claim 16 (depends on 15) The process of claim 15, wherein the charge density is about 2.5 mEq/g of solids to about 4 mEq/g of solids, and wherein the bridging moiety is derived from a functionally symmetric cross-linker comprising a di-acrylate compound, a bis(acrylamide) compound, a di-epoxide compound, a polyazetidinium compound, N,N′-methylene-bis-methacrylamide, a poly(alkylene glycol) diglycidyl ether, or any combination thereof. ### Claim 17 (depends on 16) The process of claim 16, wherein the polyamine partially crosslinked with the bridging moiety has a charge density of about 2.5 mEq/g of solids to about 3.5 mEq/g of solids, an azetidinium equivalent weight of 2,000 to about 3,500, a weight average molecular weight of 900,000 to about 1,700,000, and contains less than 10,000 ppm of 1,3-dichloro-2-propanol. ### Claim 18 (depends on 15) The process of claim 15, wherein the plurality of fibers comprises cellulose fibers or synthetic fibers. ### Claim 19 A strengthening resin, comprising a polyamidoamine partially crosslinked with a bridging moiety and having azetidinium ions, a charge density of about 2.5 mEq/g of solids to about 4 mEq/g of solids, an azetidinium equivalent weight of 2,000 to about 3,500, a weight average molecular weight of 900,000 to about 1,700,000, and contains less than 10,000 ppm of 1,3-dichloro-2-propanol, wherein the bridging moiety is derived from a functionally symmetric cross-linker comprising a di-acrylate compound, a bis(acrylamide) compound, a di-epoxide compound, a polyazetidinium compound, N,N′-methylene-bis-methacrylamide, a poly(alkylene glycol) diglycidyl ether, or any combination thereof, and wherein the azetidinium ions are formed by reacting epichlorohydrin and the polyamidoamine partially crosslinked with the bridging moiety. ### Claim 20 (depends on 19) The strengthening resin of claim 19, wherein the polyamidoamine partially crosslinked with the bridging moiety has a charge density of about 2.5 mEq/g of solids to about 3.5 mEq/g of solids, and wherein the functionally symmetric cross-linker comprises the di-acrylate compound, the bis(acrylamide) compound, the di-epoxide compound, N,N′-methylene-bis-methacrylamide, the poly(alkylene glycol) diglycidyl ether, or any combination thereof.