| 摘要 |
PROBLEM TO BE SOLVED: To obtain a polysiloxane composite polymer particle capable of forming a film excellent in stain resistance, weathering resistance, gloss and adhesion, and to provide a process for preparing the same. SOLUTION: The objective polysiloxane composite polymer particle comprises a core portion (A) and a shell portion (B) covering it, the core portion (A) being a crosslinked polymer and the shell portion (B) being a non-crosslinked polymer, and further has a polysiloxane around the surface of the shell portion (B). The process for preparing the polysiloxane composite polymer particle comprises a first step wherein a polymerizable monomer containing 0.01-5 wt.% of a crosslinkable monomer is polymerized by emulsion polymerization thereby forming a crosslinked polymer particle in a latex form, a second step wherein a polymerizable monomer containing no crosslinkable monomer is polymerized in the presence of the crosslinked polymer particle in the latex form obtained in the first step thereby enveloping the crosslinked polymer particle obtained in the first step in a non-crosslinked polymer and a third step wherein either an alkoxy silane compound or a low mol.wt. organosiloxane compound, or both of them are added in the presence of the polymer particle obtained in the second step thereby effecting condensation reaction.
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