Coating compositions for coating fibre cement board

Patent metadata

Field	Value
Publication number	US-2018305574-A1
Application number	US-201615769611-A
Country	US
Kind code	A1
Filing date	Oct 19, 2016
Priority date	Oct 20, 2015
Publication date	Oct 25, 2018
Grant date	—

Abstract

The present invention relates to the use of coating compositions for coating fibre cement boards, which contain at least one acrylate based aqueous polymer dispersions as a binder. The present invention further relates to specific acrylate based aqueous polymer dispersions and to a process for preparing these specific acrylate based aqueous polymer dispersions.

First claim

1 . A method for coating a fiber cement board, comprising applying a coating composition to a surface of the fiber cement board, the coating composition comprising as a binder an aqueous polymer dispersion, which is obtained by free-radically initiated aqueous emulsion polymerization of ethylenically unsaturated monomers M, which comprise:
80 to 99.9% by weight, based on the total weight of monomers M, of at least one monoethylenically unsaturated monomer M1, selected from C 1 -C 10 alkyl acrylates and C 1 -C 10 alkyl methacrylates; 0.1 to 5% by weight, based on the total weight of monomers M, of a monoethylenically unsaturated monomer M2, which is methacrylic acid; and optionally 0 to 19.9% by weight, based on the total weight of monomers M, of one or more ethylenically unsaturated monomers M3, which are different from monomers M1 and M2; wherein the polymerized monomers M comprise less than 10% by weight, based on the total weight of monomers M, of vinylaromatic monomers and less than 0.1% by weight, based on the total weight of monomers M, of ethylenically acidic monomers different from methacrylic acid, wherein the dispersed polymer of the aqueous polymer dispersion has a glass transition temperature Tg in the range from 25 to 75° C., or, in case of a multi-stage polymer a weight average glass transition temperature Tg in the range from 25 to 75° C., and wherein the aqueous polymer dispersion comprises an emulsifier combination comprising i. at least one non-ionic emulsifier having a polyoxyethylene group and ii. at least one anionic emulsifier, wherein the emulsifier combination comprises less than 10%, based on the total weight of the emulsifier combination of anionic emulsifiers having one or more aromatic bound sulfonate groups.

2 . The method of claim 1 , wherein the anionic emulsifier is selected from the group consisting of C 8 -C 22 -alkyl sulfonates, mono-C 8 -C 22 -alkyl sulfates, and the salts of semi esters of sulphuric acid with ethoxylated C 8 -C 22 -alkanols, and mixtures thereof.

3 . The method of claim 1 , wherein the non-ionic emulsifier is selected from ethoxylated C 10 -C 20 -alkanols, and mixtures thereof.

4 . The method of claim 3 , wherein the ethoxylated C 10 -C 20 -alkanol comprises at least one ethoxylated C 10 -C 20 -alkanol having a degree of ethoxylation in the range from 25 to 60.

5 . The method of any of claim 1 , wherein polymer dispersion satisfies at least one of the following features x1 to x5 or any combination thereof:
x1 the total amount of emulsifiers contained in the aqueous polymer dispersion is from 0.5 to 5% by weight, based on the dispersed polymer contained in the polymer dispersion; x2 the weight ratio of anionic emulsifier to non-ionic emulsifier contained in the aqueous polymer dispersion is from 1:1.5 to 5:1; x3 the monomer M1 is selected from mixtures of methylmethacrylate with at least one further monomer M1, which is selected from n-butyl acrylate, isobutyl acrylate, and C 5 -C 10 -alkylacrylates; mixtures of tert.-butylacrylate with at least one further monomer M1, which is selected from n-butyl acrylate, isobutyl acrylate, and C 5 -C 10 -alkylacrylates; and mixtures of methylmethacrylate and tert.-butylacrylate with at least one further monomer M1, which is selected from n-butyl acrylate, isobutyl acrylate, and C 5 -C 10 -alkylacrylates; x4 dispersed polymer of the aqueous polymer dispersion has a glass transition temperature Tg in the range from 30 to 65° C., or, in case of a multi-stage polymer a weight average glass transition temperature Tg in the range from 30 to 65° C.; x5 the polymer dispersion has a VOC of less than 1000 ppm.

6 . The method of claim 1 , wherein the aqueous polymer dispersion, is obtained by free-radically initiated aqueous emulsion polymerization of ethylenically unsaturated monomers M, wherein at least 95% of the monomers M are added to the polymerization reaction under polymerization conditions.

7 . The method of claim 6 , wherein the monomers M2 are added during the addition of monomers M1 and wherein the period for the addition of monomers M2 is at least 30% of the period for the addition of monomers M1.

8 . The method of claim 1 , where the coating composition comprises at least one pigment.

9 . The method of claim 1 , wherein the coating composition is a clear coat.

10 . (canceled)

11 . An aqueous polymer dispersion, which is obtained by free-radically initiated aqueous emulsion polymerization of ethylenically unsaturated monomers M, which comprise:
80 to 99.9% by weight, based on the total weight of monomers M, of at least one monoethylenically unsaturated monomer M1, selected from C 1 -C 10 alkyl acrylates and C 1 -C 10 alkyl methacrylates; 0.1 to 5% by weight, based on the total weight of monomers M, of a monoethylenically unsaturated monomer M2, which is methacrylic acid; and optionally 0 to 19.9% by weight, based on the total weight of monomers M, of one ore more ethylenically unsaturated monomers M3, which are different from monomers M1 and M2; wherein the polymerized monomers M comprise less than 10% by weight, based on the total weight of monomers M, of vinylaromatic monomers and less than 0.1% by weight, based on the total weight of monomers M, of ethylenically acidic monomers different from methacrylic acid, wherein the dispersed polymer of the aqueous polymer dispersion has a glass transition temperature Tg in the range from 25 to 75° C., or, in case of a multi-stage polymer a weight average glass transition temperature Tg in the range from 25 to 70° C., and wherein the aqueous polymer dispersion comprises an emulsifier combination comprising i. at least one non-ionic emulsifier having a polyoxyethylene group, which is selected from ethoxylated C 10 -C 20 -alkanols and comprises at least one ethoxylated C 10 -C 20 -alkanol having a degree of ethoxylation in the range from 25 to 60; and ii. at least one anionic emulsifier, which is selected from C 8 -C 22 -alkyl sulfonates, mono-C 8 -C 22 -alkyl sulfates, and the salts of semi esters of sulphuric acid with ethoxylated C 8 -C 22 -alkanol s, wherein the emulsifier combination comprises less than 10%, based on the total weight of the emulsifier combination of anionic emulsifiers having one or more aromatic bound sulfonate groups.

12 . The aqueous polymer dispersion of claim 11 , wherein the aqueous polymer dispersion satisfies at least one of the features a) to e) or any combination thereof
a) the total amount of emulsifiers contained in the aqueous polymer dispersion is from 0.5 to 5% by weight, based on the dispersed polymer contained in the polymer dispersion; b) the weight ratio of anionic emulsifier to non-ionic emulsifier contained in the aqueous polymer dispersion is from 1:1.5 to 5:1; c) the monomer M1 is selected from mixtures of methylmethacrylate with at least one further monomer M1, which is selected from n-butyl acrylate, isobutyl acrylate, and C 5 -C 10 -alkylacrylates; mixtures of tert.-butylacrylate with at least one further monomer M1, which is selected from n-butyl acrylate, isobutyl acrylate, and C 5 -C 10 -alkylacrylates; and mixtures of methylmethacrylate and tert.-butylacrylate with at least one further monomer M1, which is selected from n-butyl acrylate, isobutyl acrylate, and C 5 -C 10 -alkylacrylates; d) the dispersed polymer of the aqueous polymer dispersion has a glass transition temperature Tg in the range from 30 to 60° C., or, in case of a multi-stage polymer a weight average glass transition temperature Tg in the range from 30 to 60° C.; e) the polymer dispersion has a VOC of less than 1000 ppm.

13 . The aqueous polymer dispersion of claim 11

Assignees

• Basf Se

Inventors

• Tissier Nicolas
• Mollat Du Jourdin Xavier
• Denu Hans-Juergen

Classifications

• C04B41/483 Primary

  Polyacrylates · CPC title

• C09D7/65

  macromolecular (C09D7/41-C09D7/48 take precedence) · CPC title

• C09D7/63

  organic · CPC title

• C04B41/63

  Macromolecular compounds · CPC title

• C04B28/02

  containing hydraulic cements other than calcium sulfates · CPC title