Patent EA-001896-B1 (EA)
Title: Water-redispersible powdered film-forming polymer composition, process for preparing same, pseudolatex based thereon
Inventor: GUERIN GILLES
IPC: C04B40/00
Filed: 1996-10-21
Abstract: 1. A water-redispersible pulverulent composition, comprising: a powder of one or more water-insoluble film-forming polymers prepared from at least one ethylenically unsaturated monomer; at least one nonionic polyoxyalkylenated surfactant; and at least one water-soluble polyelectrolyte belonging to the family of weak polyacids characterised with pK from 3 to 6 in the form of free acid. 2. A pulverulent composition according to Claim 1, wherein the water-insoluble film-forming polymers are vinyl or acrylate homopolymers and vinyl acetate, butadiene-styrene, acrylate-styrene, acrylate and butadieneacrylatestyrene copolymers. 3. A pulverulent composition according to Claim 1 or 2, wherein the water-insoluble film-forming polymer has a level of surface acidity of not more than 100 microequivalents of -COOH functions per gram of polymer. 4. A pulverulent composition according to any of Claims 1-3, wherein the nonionic surfactant is selected from the group consisting of: ethoxylated or ethoxy/propoxylated fatty alcohols, ethoxylated or ethoxy/propoxylated triglycerides, ethoxylated or ethoxy/propoxylated fatty acids, ethoxylated or ethoxy/propoxylated sorbitan esters, ethoxylated or ethoxy/propoxylated fatty amines, ethoxylated or ethoxy/propoxylated bis(1-phenylethyl)phenols, ethoxylated or ethoxy/propoxylated tris(1-phenylethyl)phenols, ethoxylated or ethoxy/propoxylated alkylphenols. 5. A pulverulent composition according to any of Claims 1-4, wherein the water-soluble polyelectrolyte is selected from organic origin weak polyacids characterised with pK from 3 to 6, obtained by monomer polymerization, having the following general formula:   wherein R1-R4 can be identical or different and are H, CH3, CO2H or (CH2)nCO2H with n=0-4. 6. A pulverulent composition according to Claim 5, wherein the polyelectrolytes have a weight average molecular mass of less than 20,000 g/mole. 7. A pulverulent composition according to any of Claims 1-6, further comprising at least one additional ionic surfactant. 8. A pulverulent composition according to any of Claims 1-7, wherein the content of powder of film-forming polymer is between 40 and 90 parts by weight per 100 parts of the pulverulent composition. 9. A pulverulent composition according to any of Claims 1-8, wherein the amount of nonionic surfactant varies between 1 and 20 parts by weight per 100 parts of the pulverulent composition. 10. A pulverulent composition according to any of Claims 1-9, wherein the amount of water-soluble polyelectrolyte is between 7 and 50 parts by weight per 100 parts of the pulverulent composition. 11. A pulverulent composition according to any of Claims 7-10, wherein the weight ratio of the nonionic surfactant and the additional surfactant is between 5 and 10. 12. A pulverulent composition according to any of Claims 1-11, wherein the weight ratio of the nonionic surfactant and the water-soluble polyelectrolyte is between 30:70 and 10:90. 13. A pulverulent composition according to any of Claims 1-12, further comprising a powdered mineral filler of particle size less than 10 μm, preferably, less than 3 μm. 14. A process for the preparation of a pulverulent composition according to any of Claims 1-13, comprising: removing the water from an aqueous emulsion comprising water-insoluble film-forming polymer prepared by aqueous emulsion polymerization and at least said one nonionic surfactant, at least said one water-soluble polyelectrolyte selected from weak polyacids characterised with pK from 3 to 6 in the form of free acid, and, optionally, at least one additional surfactant or one anti-caking agent; and spraying the dry residue into a powder of desired particle size. 15. A process according to Claim 14, wherein the aqueous emulsion has a dry extract of between 30 and 70% by weight. 16. A process according to any of Claims 14 and 15, wherein drying is carried out by atomization. 17. A process according to Claim 16, wherein all the amount or the part of mineral filler is added during the atomization. 18. A pseudolatex obtained by redispersion of a pulverulent composition as defined in any of Claims 1-13 in water. 19. A use of pseudolatex according to Claim 18 or a pulverulent composition as defined in any of Claims 1-13 as additions to hydraulic binders, adhesives, paints and paper coating compositions.