Preparation of an aqueous dispersion of copolymer particles of vinyl acetate and a cyclic ketene acetal monomer

Patent metadata

Field	Value
Publication number	US-11111329-B2
Application number	US-202016822292-A
Country	US
Kind code	B2
Filing date	Mar 18, 2020
Priority date	Apr 10, 2019
Publication date	Sep 7, 2021
Grant date	Sep 7, 2021

Abstract

The present invention relates to a method comprising the steps of a) contacting under emulsion polymerization conditions vinyl acetate; a cyclic ketene acetal monomer; and a monoethylenically unsaturated acid monomer or a salt thereof; to form an aqueous dispersion of copolymer particles comprising structural units of vinyl acetate, the cyclic ketene acetal, and the monoethylenically unsaturated acid monomer or a salt thereof; wherein the cyclic ketene acetal monomer is characterized by following structure:where n and the R groups are as defined herein. The method of the present invention provides a water-borne dispersion that is substantially free of volatile organic solvents and that provides a readily degradable polymer that is useful, for example, in the manufacture of biodegradable packaging products.

First claim

The invention claimed is:

1. A method for preparing an aqueous dispersion of vinyl acetate-cyclic ketene acetal copolymer particles comprising the steps of:
a) contacting under emulsion polymerization conditions at a temperature in the range of from 30° C. to 55° C., and at a pH in the range of from 6.0 to 9.0:
1) 75 to 98.5 parts by weight of vinyl acetate;
2) 1 to 20 parts by weight of a cyclic ketene acetal monomer; and
3) 0.05 to 5 parts by weight of a monoethylenically unsaturated acid monomer or a salt thereof; to form an aqueous dispersion of copolymer particles comprising structural units of vinyl acetate, the cyclic ketene acetal, and the monoethylenically unsaturated acid monomer or a salt thereof;

wherein the cyclic ketene acetal monomer is the following structure:

where n is 0, 1, or 2;
R is H or C 1 -C 6 -alkyl;
R 1 and R 2 are each independently H, C 1 -C 12 -alkyl, phenyl, or vinyl; or R 1 and R 2 together with the carbon atoms to which they are attached, form a fused benzene ring or a fused C 3 -C 7 cycloaliphatic ring; and
R 1 ′ and R 2 ′ are each independently H or C 1 -C 12 -alkyl; or R 1 and R 1 ′ and/or R 2 and R 2 ′ form an exocyclic double bond;
with the proviso that when n is 1:
R 3 and R 3 ′ are each independently H, C 1 -C 12 -alkyl, phenyl, or R 3 and R 3 ′ form an exocyclic double bond or a spirocycloaliphatic group or spiro-2-methylene-1,3-dioxepane group;
with the proviso that when n is 2:
each R 3 is H, C 1 -C 2 -alkyl, or together with the carbon atoms to which they are attached form a double bond, a fused benzene ring, or a fused C 3 -C 7 -cycloaliphatic ring.

2. The method of claim 1 wherein the cyclic ketene acetal monomer, the vinyl acetate, and the monoethylenically unsaturated acid monomer or a salt thereof are contacted under emulsion polymerization conditions at a temperature in the range of from 35° C. to 55° C., and at a pH in the range of from 6.5 to 8.5.

3. The method of claim 2 wherein cyclic ketene acetal monomer is selected from the group consisting of:

4. The method of claim 3 wherein the cyclic ketene acetal monomer is 2-methylene-1,3-dioxepane, and the monoethylenically unsaturated acid monomer is a sulfur acid containing monomer or a salt thereof; wherein the 2-methylene-1,3-dioxepane, the vinyl acetate, and the sulfur acid containing monomer or a salt thereof are contacted under emulsion polymerization conditions at a temperature in the range of from 35° C. to 50° C. and at a pH in the range of from 7.5 to 8.5; wherein the aqueous dispersion of polymer particles comprises structural units of vinyl acetate and 2-methylene-1,3-dioxepane.

5. The method of claim 4 wherein the sulfur acid containing monomer or salt thereof is selected from the group consisting of 2-acrylamido-2-methyl-1-propanesulfonic acid, salts of 2-acrylamido-2-methyl-1-propanesulfonic acid, vinyl sulfonic acid, salts of vinyl sulfonic acid, 2-sulfoethyl acrylate, 2-sulfoethyl methacrylate, 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate, sodium styrene sulfonate, 2-propene-1-sulfonic acid and salts of 2-propene-1-sulfonic acid.

6. The method of claim 5 wherein the sulfur acid containing monomer or salt thereof is a salt of 2-acrylamido-2-methyl-1-propanesulfonic acid.

7. The method of claim 6 wherein the aqueous dispersion of polymer particles further comprises less than 20 weight percent 4-hydroxybutyl acetate based on the weight of structural units of 2-methylene-1,3-dioxepane in the polymer particles; wherein the 2-methylene-1,3-dioxepane, the vinyl acetate, and the sulfur acid containing monomer or a salt thereof are contacted under emulsion polymerization conditions at a temperature in the range of from 35° C. to 45° C.

8. The method of claim 4 wherein the aqueous dispersion of polymer particles further comprises less than 10 weight percent 4-hydroxybutyl acetate based on the weight of structural units of 2-methylene-1,3-dioxepane in the polymer particles.

9. The method of claim 5 wherein the aqueous dispersion of polymer particles further comprises less than 2 weight percent 4-hydroxybutyl acetate based on the weight of structural units of 2-methylene-1,3-dioxepane in the polymer particles.

10. The method of claim 7 wherein the aqueous dispersion of polymer particles further comprises less than 1 weight percent 4-hydroxybutyl acetate based on the weight of structural units of 2-methylene-1,3-dioxepane in the polymer particles.

Assignees

• Rohm & Haas

Inventors

• Carter Matthew
• Even Ralph C
• Hejl Andrew

Classifications

• C08F18/08 Primary

  Vinyl acetate · CPC title

• C08L31/04 Primary

  Homopolymers or copolymers of vinyl acetate · CPC title

• C08J3/03 Primary

  in aqueous media · CPC title

• C08G63/005

  Polyesters prepared from ketenes · CPC title

• B65D65/466

  Bio- or photodegradable packaging materials · CPC title