Preparation of a coatings formulation with alkali swellable polymer particles

Patent metadata

Field	Value
Publication number	US-11161986-B2
Application number	US-201816497475-A
Country	US
Kind code	B2
Filing date	Feb 26, 2018
Priority date	Mar 27, 2017
Publication date	Nov 2, 2021
Grant date	Nov 2, 2021

Abstract

The present invention relates to a process comprising the step of contacting an aqueous dispersion of swelled polymer particles with a rheology modifier and a binder to form a coatings composition with a VOC of less than 50 g/L. The swelled polymer particles arise from neutralization of alkali swellable polymer particles having a high acid core content and a low T g shell. The composition arising from the process of the present invention is useful for improving open time, especially for low VOC coatings applications.

First claim

The invention claimed is:

1. A process for preparing a coatings composition comprising the steps of a) contacting an aqueous dispersion of alkali swellable polymer particles with a base to form an aqueous dispersion of swelled polymer particles; and b) contacting the aqueous dispersion of swelled polymer particles with a rheology modifier and a binder to form a coatings composition with a VOC of less than 50 g/L; wherein the alkali swellable polymer particles comprise a shell having a T g of not greater than 25° C. and an acid functionalized core; wherein the core-to-shell ratio is in the range of 1:3.2 to 1:6; and wherein the coatings composition comprises 2 to 20 percent by weight of swelled polymer particles based on the weight of total solids in the coatings composition.

2. The process of claim 1 wherein the aqueous dispersion of alkali swellable polymer particles has a solids content in the range of from 10 to 35 weight percent, based on the weight of the aqueous dispersion of alkali swellable polymer particles.

3. The process of claim 2 wherein the viscosity of the dispersion of alkali swellable polymer particles prior to base addition is in the range of 10-100 mPa·s, and the aqueous dispersion of swelled polymer particles has a viscosity that is at least 50 mPa·s higher than the alkali swellable polymer particles.

4. The process of claim 1 wherein the acid functionalized core of the alkali swellable polymer particles comprises from 30 to 50 weight percent structural units of a carboxylic acid monomer, and from 50 to 70 weight percent structural units of a nonionic ethylenically unsaturated monomer, based on the weight of the core; and wherein the shell of the alkali swellable polymer particles has a T g of not greater than 20° C. and comprises structural units of a monomer having a T g of greater than 50° C., structural units of a monomer having a T g of less than 10° C., and structural units of an acid monomer.

5. The process of claim 4 wherein the acid functionalized core of the alkali swellable polymer particles comprises from 35 to 45 weight percent structural units of methacrylic acid or acrylic acid, based on the weight of the core; and from 55 to 65 weight percent structural units of the nonionic ethylenically unsaturated monomer, wherein the nonionic ethylenically unsaturated monomer is methyl methacrylate or butyl methacrylate; wherein the shell comprises from 40 to 60 weight percent structural units of the monomer having a T g of greater than 50° C., wherein the monomer having a T g of greater than 50° C. includes styrene or methyl methacrylate; from 38 to 59 weight percent structural units of the monomer having a T g of less than 10° C., wherein the monomer having a T g of less than 10° C. is butyl acrylate; and from 0.2 to 5 weight percent structural units of the acid monomer, wherein the acid monomer is methacrylic acid or acrylic acid; and wherein the average diameter of the alkali swellable polymer particles is in the range of from 150 nm to 900 nm.

6. The process of claim 5 wherein the base is a non-volatile base, wherein the aqueous dispersion of the swelled polymer particles has a viscosity at least 100 mPa·s higher than the aqueous dispersion of alkali swellable particles, and wherein the base is contacted with the alkali swellable polymer particles at a temperature in the range of from 15° C. to 60° C.

7. The process of claim 6 wherein the base is LiOH, NaOH, or KOH; wherein the base is contacted with the alkali swellable polymer particles at a temperature in the range of from 20° C. to 40° C.; wherein the viscosity of the swelled polymer particles is in the range of from 200 mPa·s to 1500 mPa·s, and wherein the coating composition exhibits a change of viscosity of less than 500 mPa·s after the aqueous dispersion of swelled polymer particles is contacted with the binder and the rheology modifier.

8. The process of claim 1 wherein the concentration of swelled polymer particles is in the range of from 5 to 15 weight percent, based on the weight of solids in the coatings composition; the concentration of binder solids is in the range of from 5 to 40 weight percent, based on the weight of solids in the coatings composition; and the concentration of rheology modifier is in the range of from 0.5 to 5 weight percent, based on the weight of solids in the coatings composition.

9. The process of claim 8 wherein the coatings composition further includes at least one component selected from the group consisting of dispersants, pigments, defoamers, surfactants, solvents, extenders, coalescents, biocides, opaque polymers, and colorants.

10. A process for preparing a coatings composition comprising the step of contacting an aqueous dispersion of swelled polymer particles with a rheology modifier and a binder to form a coatings composition with a VOC of less than 50 g/L, wherein the swelled polymer particles have a core-shell morphology, wherein the shell has a T g of not greater than 25° C. and the core comprises water and a salt of a carboxylic acid; and wherein the coatings composition comprises from 1 to 20% by weight of the swelled polymer particles based on the total solids in the coatings composition.

Assignees

• Dow Global Technologies Llc
• Rohm & Haas

Inventors

• Bardman James K
• Derocher Jonathan
• Hejl Andrew
• Vandyk Anthony K
• Wang Lin
• Yeung Kimy

Classifications

• C08L33/08

  Homopolymers or copolymers of acrylic acid esters · CPC title

• C09D7/43

  Thickening agents · CPC title

• C09D133/08

  Homopolymers or copolymers of acrylic acid esters · CPC title

• C09D5/024 Primary

  characterised by the additives · CPC title

• C08J3/005 Primary

  Processes for mixing polymers · CPC title