# US 2025/0154723 A1 · Interpenetrating polymer network for paper and paperboard coating compositions

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- Number: US 2025/0154723 A1
- Document ID: US20250154723A1
- Status: Published application
- Kind: A1
- Application number: 18/925,076
- Filed: 2024-10-24
- Published: 2025-05-15
- Earliest claimed: 2023-11-13
- Assignees: Buckman Laboratories International, Inc.
- Applicants: Buckman Laboratories International, Inc.
- Inventors: Samuel TEKOBO; Zhiyi ZHANG
- Web page: https://patentgrep.com/patent/US20250154723A1

## CPC

- C08L 33/26: Homopolymers or copolymers of acrylamide or methacrylamide
- D21H 19/12: applied as a solution using water as the only solvent, e.g. in the presence of acid or alkaline compounds
- C08F 265/10: on to polymers of amides or imides
- C09D 7/61: inorganic
- C09D 7/63: organic
- C09D 103/02: Starch; Degradation products thereof, e.g. dextrin
- C09D 133/26: Homopolymers or copolymers of acrylamide or methacrylamide
- D21H 17/28: Starch
- D21H 17/375: {Poly(meth)acrylamide}
- D21H 19/00: Coated paper (coated fibreboard D21J1/08); Coating material (recording sheets characterised by the coating used to improve ink, dye or pigment receptivity B41M5/50)
- C08L 2205/04: containing interpenetrating networks
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- 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
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)

## Abstract

An interpenetrating polymer network (IPN) is described, as well as coating compositions including a combination of a starch solution and the IPN for coating a paper or paperboard. The IPN includes a first copolymer of acrylamide and acrylic acid with a second copolymer of acrylamide and acrylic acid. The first copolymer and the second copolymer are different from each other at least with respect to average molecular weight. Processes of making the IPN and the coating composition as well as coating the paper or paperboard with the coating composition are also described.

## Claims

### Claim 1

An interpenetrating polymer network (IPN) comprising a) a first copolymer that is the reaction product of i) a polymerizable composition comprising at least one acrylamide monomer and at least one acrylic acid monomer and ii) a reactive prepolymer of acrylamide and acrylic acid and b) a second co-polymer of at least acrylamide and acrylic acid, wherein the first copolymer and the second copolymer are different from each other at least with respect to average molecular weight.

### Claim 2 (depends on 1)

The IPN of claim 1, wherein the first copolymer has a first average molecular weight and the second copolymer has a second average molecular weight, and the first average molecular weight is at least 1.5 times higher than the second average molecular weight.

### Claim 3 (depends on 1)

The IPN of claim 1, wherein the first copolymer has a first average molecular weight and the second copolymer has a second average molecular weight, and the first average molecular weight is from 1.5 times to 15 times higher than the second average molecular weight.

### Claim 4 (depends on 1)

The IPN of claim 1, wherein the first copolymer has a first average molecular weight and the second copolymer has a second average molecular weight, and the first average molecular weight is from 2 times to 10 times higher than the second average molecular weight.

### Claim 5 (depends on 1)

The IPN of claim 1, wherein the first copolymer is present in an amount of from 70% to 90% by weight of the IPN, and the second copolymer is present in an amount of from 10% to 30% by weight of the IPN.

### Claim 6 (depends on 1)

The IPN of claim 1, wherein the first copolymer is present in an amount of from 75% to 85% by weight of the IPN, and the second copolymer is present in an amount of from 15% to 25% by weight of the IPN.

### Claim 7 (depends on 1)

The IPN of claim 1, wherein the IPN has a viscosity of from 250 cPS to 3000 cPS at 25 deg C. and 1 atm.

### Claim 8 (depends on 1)

The IPN of claim 1, wherein the first copolymer has a viscosity of from 250 cPS to 4000 cPS at 25 deg C. and 1 atm.

### Claim 9 (depends on 1)

The IPN of claim 1, wherein the IPN has a concentration of 26% to 32% of active solids.

### Claim 10 (depends on 1)

The IPN of claim 1, wherein the reactive prepolymer is a reaction product of a polymerizable composition comprising an acrylamide monomer, an acrylic acid monomer, and sodium hydroxide and the reactive prepolymer having radical chains present.

### Claim 11 (depends on 1)

The IPN of claim 1, wherein the reactive prepolymer has at least one of the following structures:
where x/y is from 0.05 to 0.2, and n is from 3 to 4000, and the “.” represents a radical or dangling covalent bond, and wherein the reactive prepolymer is a living polymer.

### Claim 12 (depends on 1)

The IPN of claim 1, wherein the first copolymer has at least one of the following structures:
wherein x/y is 0.05 to 0.2, n is from 300 to 5000, and the first copolymer is a dead polymer.

### Claim 13 (depends on 1)

The IPN of claim 1, wherein the second copolymer has at least one of the following structures:
wherein x/y is 0.05 to 0.2, n is from 3 to 500, and the second copolymer is a dead polymer.

### Claim 14 (depends on 1)

The IPN of claim 1, wherein the IPN is a sequential interpenetrating polymer network or a sequential semi-interpenetrating polymer network.

### Claim 15 (depends on 1)

A coating composition comprising the IPN of claim 1 and a cooked starch solution.

### Claim 16 (depends on 15)

The coating composition of claim 15, wherein the IPN is present in an amount of from about 5 wt % to about 25 wt %, based on the dry starch weight of the coating composition.

### Claim 17 (depends on 15)

The coating composition of claim 15, wherein the coating composition comprises a chemical structure (4):
wherein n is from 20 to 4000.

### Claim 18 (depends on 15)

The coating composition of claim 15, wherein the viscosity of the coating composition is within 5% of the viscosity of the cooked starch solution.

### Claim 19 (depends on 15)

The coating composition of claim 15, wherein the viscosity of the coating composition is within 1% of the viscosity of the cooked starch solution.

### Claim 20 (depends on 15)

A paper or paperboard product comprising paper or paperboard and a dry coating of the coating composition of claim 15 on at least a portion of said paper or paperboard.

### Claim 21 (depends on 1)

A method of forming the IPN of claim 1, said method comprising
(i) polymerizing a first solution comprising an acrylamide monomer and acrylic acid monomer to obtain the reactive prepolymer; (ii) adding a second solution comprising an acrylamide monomer and acrylic acid monomer to the reactive prepolymer and polymerizing the second solution in the presence of the reactive prepolymer and terminating the reaction to obtain the first copolymer; and (iii) adding a third solution to the first copolymer and polymerizing the third solution in the presence of the first copolymer to form the second copolymer amongst the first copolymer.

### Claim 22 (depends on 21)

The method of claim 21, wherein the first solution, second solution, and third solution have a total weight, and the first solution is from 35% to 65 wt % of the total weight, the second solution is from 10% to 40 wt % of the total weight, and the third solution is from 10% to 40 wt % of the total weight.

### Claim 23 (depends on 21)

The method of claim 21, wherein the first solution, second solution, and third solution each further comprise sodium hydroxide.

### Claim 24 (depends on 21)

The method of claim 21, wherein the polymerizing steps are carried out by heating the solution and adding an initiator and sodium formate over a period of time.

### Claim 25 (depends on 21)

The method of claim 21, wherein the first solution, second solution, and third solution result from a single solution that is separated to obtain the first solution, second solution, and third solution.