Liquid emulsion polymers useful as pH responsive thickeners for aqueous systems

• US 4,384,096 A
• Filed: 12/23/1980
• Issued: 05/17/1983
• Est. Priority Date: 08/27/1979
• Status: Expired due to Term

• Current Assignee: The Dow Chemical Company (Dow, Inc.)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Sonnabend, Lawrence F.
• Primary Examiner(s): Michl, Paul R.
• Application Number:
  US06/219,480
• Time in Patent Office: 875 Days
• Field of Search: 260/29.6 H, 260/29.6 TA, 260/29.6 RW, 526/313, 526/317, 526/318, 526/320
• US Class Current: 526/313
• CPC Class Codes: C07C 69/54 Acrylic acid esters; Methacrylic acid esters
• CPC Class Codes: C08F 220/286 and containing polyethylene oxide in the alcohol moiety, e.g. methoxy polyethylene glycol (meth)acrylate
• CPC Class Codes: C08F 246/00 Copolymers in which the nature of only the monomers in minority is defined
• CPC Class Codes: C08F 290/062 Polyethers
• CPC Class Codes: C08L 33/02 Homopolymers or copolymers of acids; Metal or ammonium salts thereof
• CPC Class Codes: C08L 33/08 Homopolymers or copolymers of acrylic acid esters
• CPC Class Codes: C09D 7/43 Thickening agents

Abstract

Novel aqueous liquid emulsion polymers are prepared by the copolymerization of (A) about 15-60 weight percent of a C₃ -C₈ α,β-ethylenically unsaturated carboxylic acid monomer, preferably acrylic or methacrylic acid or a mixture thereof with itaconic or fumaric acid, (B) about 15-80 weight percent of a nonionic copolymerizable C₂ -C₁₂ α,β-ethylenically unsaturated monomer, preferably a monovinyl ester such as ethyl acrylate or a mixture thereof with styrene, acrylonitrile, vinyl chloride or vinyl acetate, and (C) about 1-30 weight percent of certain nonionic vinyl surfactant esters, such as nonylphenoxypoly(ethyleneoxy)₉ ethyl acrylate, to give an emulsion copolymer stable as an aqueous colloidal dispersion at an acid pH lower than about 5.0 but responsive to pH adjustment with base. These emulsion polymers adjusted to a pH of about 5.5 or higher are effective thickeners for a wide variety of aqueous systems including cosmetic products, drilling muds, and particularly aqueous coating compositions such as latex paint.

Claims

1. A liquid emulsion polymer useful as a pH responsive thickener for aqueous compositions comprising an aqueous emulsion copolymer of:

A. about 15-60 weight percent based on total monomers of at least one C₃ -C₈ α

,β

-ethylenically unsaturated carboxylic acid monomer of the formula;

##STR10## where R is H and R'"'"' is H, C₁ -C₄ alkyl, or --CH₂ COOX;

R is --COOX and R'"'"' is H or --CH₂ COOX;

or,

R is CH₃ and R'"'"' is H; and

X is H or C₁ -C₄ alkyl;

B. about 15-80 weight percent of at least one nonionic, copolymerizable C₂ -C₁₂ α

,β

-ethylenically unsaturated monomer of the formula;

space="preserve" listing-type="equation">CH.sub.2 ═

CYZ (II)

where

Y is H and Z is --COOR, --C₆ H₄ R'"'"', CN, Cl, ##STR11## or --CH═

CH₂ ;

Y is CH₃ and Z is --COOR, --C₆ H₄ R'"'"', CN or --CH═

CH₂ ;

or

Y and Z are Cl; and

R is C₁ -C₈ alkyl or C₂ -C₈ hydroxyalkyl;

R'"'"' is H, Cl, Br, or C₁ -C₄ alkyl; and

R" is C₁ -C₈ alkyl; and

C. about 1-30 weight percent based on total monomers of at least one nonionic vinyl surfactant ester of the formula;

##STR12## where R is H or CH₃, each R'"'"' is C₁ -C₂ alkyl,

R" is C₈ -C₂₀ alkyl or C₈ -C₁₆ alkylphenyl,

n is an average number from about 6-100 and m is an average number from about 0-50 provided that n≧

m and Σ

(n+m) is about 6-100;

said polymer being stable as an aqueous colloidal dispersion at a pH lower than about 5.0 but becoming an effective thickener for aqueous systems upon adjustment to a pH of about 5.5-10.5 or higher.

2. The polymer of claim 1 where the carboxylic acid monomer (A) is methacrylic acid, acrylic acid, or a mixture thereof with fumaric or itaconic acid.

3. The polymer of claim 1 containing about 33-55 weight percent of methacrylic acid or a mixture thereof with a minor amount of itaconic acid.

4. The polymer of claim 1 where the comonomer (B) is a monovinyl ester or a mixture thereof with styrene, 2-hydroxyethyl acrylate, acrylonitrile, vinyl chloride or vinyl acetate.

5. The polymer of claim 1 where the comonomer (B) is ethyl acrylate.

6. The polymer of claim 1 where the amount of the carboxylic acid monomer (A) is from about 25 weight percent to about 60 weight percent.

7. The polymer of claim 6 where the vinyl surfactant ester is selected from the group consisting of:

(1) alkylphenoxypoly(ethyleneoxy)ethyl acrylates of the formula;

##STR13## where R is H or CH₃ ;

Y'"'"' is C₈ -C₁₆ alkyl, and n is about 6-100;

(2) alkoxypoly(ethyleneoxy)ethyl acrylates of the formula;

##STR14## where R is H or CH₃, R" is C₈ -C₂₀ alkyl, and n is about 6-50; and

(3) alkoxypoly(alkyleneoxy)ethyl acrylates of the formula;

##STR15## where R is H or CH₃, each R'"'"' is C₁ -C₂ alkyl,

R" is C₈ -C₂₀ alkyl, and,

n is about 6-50 and m is about 1-40.

8. The polymer of claim 1 consisting essentially of:

A. about 35-55 weight percent of methacrylic acid, acrylic acid or mixtures thereof with fumaric or itaconic acid;

B. about 35-50 weight percent of ethyl acrylate or mixtures thereof with styrene, 2-hydroxyethyl acrylate, acrylonitrile, vinyl chloride or vinyl acetate; and

C. about 2-20 weight percent of a vinyl surfactant ester of Formula III.

9. The polymer of claim 8 wherein the vinyl surfactant ester is an alkylphenoxypoly(ethyleneoxy)ethyl acrylate of the formula:

##STR16## where R is H or CH₃ ;

Y'"'"' is C₈ -C₁₆ alkyl, and n is about 6-100.

10. The polymer of claim 8 wherein the vinyl surfactant ester is an alkoxypoly(ethyleneoxy)ethyl acrylate of the formula:

##STR17## where R is H or CH₃, R" is C₈ -C₂₀ alkyl, and n is about 6-50.

11. The polymer of claim 8 wherein the vinyl surfactant ester is an alkoxypoly(alkyleneoxy)ethyl acrylate of the formula:

##STR18## where R is H or CH₃, each R'"'"' is C₁ -C₂ alkyl,

R" is C₈ -C₂₀ alkyl, and,

n is about 6-50 and m is about 1-40.

12. The polymer of claim 1 consisting essentially of:

A. about 40-50 weight percent of methacrylic acid;

B. about 35-50 weight percent of ethyl acrylate; and

C. about 2-12 weight percent of the methacrylic ester of a nonylphenoxypoly(ethyleneoxy)_n ethanol where n is about 6-40.

13. The polymer of claim 12 wherein about 1-15 weight percent of itaconic acid based on the total monomeric weight is substituted for a minor portion of the methacrylic acid.

14. The polymer of claim 13 containing about 40-45 weight percent of methacrylic acid and 2-10 weight percent of itaconic acid.

15. The polymer of claim 1 having an average particle size of about 500-3000 A and a Brookfield viscosity of about 50-50,000 cps as a 1 percent aqueous solution in ammonium salt form at pH 9.0 and 25°

C.

16. A liquid aqueous colloidal dispersion useful as a pH responsive polymeric thickener for aqueous compositions and containing about 10-50 weight percent of the polymer of claim 1 and having a pH of about 2.5-5.0.

17. The liquid aqueous colloidal dispersion of claim 16 where the polymer consists essentially of:

A. about 40-50 weight percent of methacrylic acid;

B. about 35-50 weight percent of ethyl acrylate; and

C. about 2-12 weight percent of the methacrylic ester of a nonylphenoxypoly(ethyleneoxy)_n ethanol where n is about 6-40.

18. A process for making the liquid aqueous colloidal dispersion of claim 16 comprising emulsion copolymerizing the monomeric mixture at a pH of about 2.5-5.0 in the presence of a free-radical producing initiator at a temperature between about 60°

-90°

C.

19. The process of claim 18 wherein the emulsion copolymerization gives a polymer having an average particle size of about 500-3000 A and a Brookfield viscosity of about 50-50,000 cps as a 1 percent aqueous solution in ammonium salt form at pH 9.0 and 25°

C.

20. The process of claim 18 wherein the monomeric mixture consists essentially of:

A. about 40-50 weight percent of methacrylic acid;

B. about 35-50 weight percent of ethyl acrylate or a mixture thereof with styrene, 2-hydroxyethyl acrylate, acrylonitrile, vinyl chloride, or vinyl acetate; and

C. about 2-12 weight percent of the methacrylic ester of an alkylphenoxypoly(ethyleneoxy)ethyl acrylate of the formula;

##STR19## where R is H or CH₃ ;

Y'"'"' is C₈ -C₁₆ alkyl, and n is about 6-100.

21. A thickened aqueous composition having a pH within the range of about 6.5-11.0 comprising an aqueous composition containing a water-soluble or dispersible material and an effective amount of a liquid emulsion polymer of claim 1.

22. The thickened aqueous composition of claim 21 wherein the aqueous composition is a slurry of titanium dioxide.

23. The thickened aqueous composition of claim 21 wherein the aqueous composition is a colloidal dispersion of a water-insoluble polymer.

24. The thickened aqueous composition of claim 21 wherein the aqueous composition is a natural, synthetic or artificial latex.

25. The thickened aqueous composition of claim 21 wherein the liquid emulsion polymer consists essentially of:

A. about 40-50 weight percent of methacrylic acid;

B. about 35-50 weight percent of ethyl acrylate; and

C. about 2-12 weight percent of the methacrylic ester of a nonylphenoxypoly(ethyleneoxy)_n ethanol where n is about 6-40.

26. A process for making a thickened aqueous composition which comprises:

(1) blending with the aqueous composition a sufficient amount of the liquid emulsion polymer of claim 1 to thicken the aqueous coating composition and

(2) adjusting the pH of said blend within a range of about 6.5-11.0 as necessary to dissolve the emulsion polymer therein and thus thicken the aqueous composition.

27. The process of claim 26 wherein the aqueous composition is a colloidal dispersion of a water-insoluble polymer.

28. The process of claim 26 wherein the aqueous composition is a natural, synthetic or artificial latex.

29. The process of claim 26 wherein the aqueous composition is a synthetic latex.

30. The process of claim 26 wherein the liquid emulsion polymer consists essentially of:

A. about 40-50 weight percent of methacrylic acid;

B. about 35-50 weight percent of ethyl acrylate; and

C. about 2-12 weight percent of the methacrylic ester of an alkylphenoxypoly(ethyleneoxy)ethyl acrylate of the formula;

##STR20## where R is H or CH₃ ;

Y'"'"' is C₈ -C₁₆ alkyl; and

n is about 6-100.