Claims
- 1. An acrylic polymer powder which is redispersible in water consisting essentially of a spray dried aqueous dispersion of an acrylic polymer consisting essentially of 85 to 99 wt % acrylate and methacrylate esters, 1-15 wt % olefinically unsaturated carboxylic acid comonomer and, optionally, up to 20 wt % other comonomers, the aqueous acrylic polymer dispersion prepared by emulsion polymerization of the monomers in the presence of a surfactant and then neutralized with a base to at least pH 7, and containing a post-added dispersing aid consisting essentially of polyvinyl alcohol.
- 2. The acrylic polymer powder of claim 1 in which the polyvinyl alcohol is 87-99 mole % hydrolyzed.
- 3. The acrylic polymer powder of claim 1 in which the polyvinyl alcohol has a degree of polymerization of 200-5000.
- 4. The acrylic polymer powder of claim 1 in which the dispersion contained 2-25 wt % polyvinyl alcohol, based on polymer content of the dispersion.
- 5. The acrylic polymer powder of claim 1 in which the dispersion contained 5-15 wt % polyvinyl alcohol, based on polymer content of the dispersion.
- 6. The acrylic polymer powder of claim 1 which also contains melamine formaldehyde, lignosulfonate salt, polyvinyl pyrrolidone, poly(vinylformamide), hydroxyethylcellulose or poly(meth)acrylate as another dispersing aid.
- 7. An acrylic polymer powder which is redispersible in water consisting essentially of a spray dried aqueous dispersion of an acrylic polymer consisting essentially of 85 to 99 wt % acrylate and methacrylate esters, 1-15 wt % olefinically unsaturated carboxylic acid comonomer and, optionally, up to 20 wt % other comonomers, the aqueous acrylic polymer dispersion prepared by emulsion polymerization of the monomers in the presence of a surfactant and then neutralized with a base to at least pH 7, and containing 2-25 wt %, based on acrylic polymer content of the dispersion, of a post-added dispersing aid consisting essentially of polyvinyl alcohol which is 87-99 mole % hydrolyzed and has a DPn of 200-5000.
- 8. The acrylic polymer powder of claim 7 in which the acid comonomer is acrylic acid, methacrylic acid, iraconic acid and/or crotonic acid.
- 9. The acrylic polymer powder of claim 8 in which the polymer contains 3-10 wt % acid comonomer.
- 10. The acrylic polymer powder of claim 9 which comprises 5-15 wt % polyvinyl alcohol.
- 11. The acrylic polymer powder of claim 9 which also contains melamine formaldehyde, lignosulfonate salt, polyvinyl pyrrolidone, poly(vinylformamide), hydroxyethylcellulose or poly(meth)acrylate as another dispersing aid.
- 12. An acrylic polymer powder which is redispersible in water consisting essentially of a spray dried aqueous dispersion of an acrylic polymer consisting essentially of 85 to 99 wt % acrylate and methacrylate esters, 1-15 wt % olefinically unsaturated carboxylic acid comonomer which is at least one of acrylic acid, itaconic acid, citraconic acid, methacrylic acid, crotonic acid or cinnamic acid, and, optionally, up to 20 wt % other comonomers, the aqueous acrylic polymer dispersion prepared by emulsion polymerization of the monomers in the presence of a surfactant and then neutralized with a base to at least pH 7 and containing 2-25 wt % based on acrylic polymer content of the dispersion, of a post-added dispersing aid consisting essentially of polyvinyl alcohol which is 87-89 mole % hydrolyzed and has a DPn of 200-5000.
Parent Case Info
This is a continuation of application Ser. No. 07/986,956, filed on Dec. 8, 1992, now abandoned.
US Referenced Citations (9)
Foreign Referenced Citations (4)
Number |
Date |
Country |
4185606-A |
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JPX |
4185607-A |
|
JPX |
314116 |
Jan 1990 |
JPX |
314117 |
Jan 1990 |
JPX |
Continuations (1)
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Number |
Date |
Country |
Parent |
986956 |
Dec 1992 |
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