The Nippon Synthetic Chemical Industry Co., Ltd.

Nippon Synthetic Industry Co., Ltd.

Kiyoharu Kitamura

Mitsuo Shibutani

Kinji Taki

Kouji Hara

Masaaki Yamada

The present invention provides an aqueous emulsion having excellent polymerization stability and standing stability and a redispersible powder. Specifically, the present invention relates to an aqueous emulsion of a polymer obtained by polymerizing an acrylic monomer in the presence of a polyvinyl alcohol containing an acetoacetic ester group; wherein the polyvinyl alcohol containing an acetoacetic ester group has block character [&#x3b7;] of 0.3 to 0.6, hydrolysis degree of at least 97% by mol and acetoacetic esterification degree of 0.01 to 1.5% by mol, and the value obtained by dividing the maximum value by the minimum value of the respective average acetoacetic esterification degree for each of the polyvinyl alcohol containing an acetoacetic ester group separated by particle size of 44 to 74, 74 to 105, 105 to 177, 177 to 297, 297 to 500 and 500 to 1680 &#x3bc;m is 1.0 to 3.0. Also, the present invention relates to a redispersible fiber obtained by drying the aqueous emulsion.

Aqueous emulsion and use thereof

A redispersible synthetic resin powder comprising particles of a polymer made from at least one monomer selected from the group consisting of ethylenically unsaturated monomers and diene monomers, and a polyvinyl alcohol resin having at least one functional group selected from the group consisting of acetoacetoxy group and mercapto group and having a block character &lsqb;&eegr;&rsqb; of 0.3 to 0.6, wherein said polyvinyl alcohol resin is adsorbed onto the surface of said particles. The powder has excellent redispersibility, blocking resistance, film forming property and water resistance, can be easily dispersed into water to form emulsions and is also useful as an admixture for cement and mortar.

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Ibaraki, Japan

Kiyoharu Kitamura