TW282475B - Acrylic multilayer polymer powder - Google Patents

Abstract

An acrylic multilayer polymer powder which comprises a coagulated powder obtained by coagulating an emulsified latex of an acrylic multilayer polymer with a polymer melt-initiating point of 235 deg.C or higher and having at least one soft polymer inner layer comprising a polymer with a glass transition point Tg of 25 deg.C or lower when polymerized alone and a rigid polymer outermost layer comprising a polymer with a glass transition point Tg of 50 deg.C or higher when polymerized alone, the coagulated powder after drying comprising not more than 40 wt% of a fine powder of a particle size of 212 (muon)m or less, and the volume of gaps of a pore size of 5 (muon)m or less of the coagulated powder after drying being not more than 0.7 cc per dry unit weight as measured by a mercurial pressure method, in which the soft polymer layer comprises a polymer prepared from 40-90 wt% of an alkyl acrylate with an alkyl group of 8 carbon atoms or less, 10-60 wt% of a monofunctional monomer with at least one vinyl group which is copolymerizable therewith and, with respect to 100 wt% of these monomer components, 0.1-10 wt% of a graft-linking agent and 0.1-10 wt% of a polyfunctional crosslinking agent with at least 2 vinyl groups; the rigid polymer layer comprises a polymer prepared from 60-100 wt% of an alkyl methacrylate with an alkyl group of 4 carbon atoms or less and 0-40 wt% of an unsaturated monomer with which it is copolymerizable; the proportion of the outermost layer to the total amount of the acrylic multilayer polymer is 10-60 wt%; the acrylic multilayer polymer comprises a 3-layer polymer of which (alpha) 20-30 wt% is an innermost polymer layer obtained by polymerizing a mixture comprising 5-70 wt% of at least one selected from alkyl acrylates with an alkyl group of 8 carbon atoms or less and styrene, 30-95 wt% of methyl methacrylate, and 0.2-5 wt% of a graft-linking agent and 1-5 wt% of a polyfunctional crosslinking agent with respect to 100 wt% of these monomers; (beta) 25-45 wt% is an intermediate polymer layer obtained by polymerizing a mixture comprising 70-90 wt% of an alkyl acrylate with an alkyl group of 8 carbon atoms or less, 10-30 wt% of an aromatic vinyl monomer, 1-3 wt% of a graft-linking agent and 0.1-1 wt% of a polyfunctional crosslinking agent with respect to 100 wt% of these monomers; and (gamma) 35-55 wt% is an outermost layer obtained by polymerizing a mixture consisting of 85-97 wt% of methyl methacrylate and 3-15 wt% of an alkyl acrylate of 4 carbon atoms or less. A desired monomer is subjected to emulsion polymerization to produce an emulsified latex of an acrylic multilayer polymer, which is then poured into a coagulating solution for coagulation.