Pulverisierbare Acrylatharze

摘要

1330661 Pulverizable acrylate resins; powder coating materials BAYER AG 11 Sept 1970 [31 Dec 1969] 43562/70 Heading C3P [Also in Division B2] Pulverizable resins having a softening point of from 75‹ to 110‹ C. and an average molecular weight of from 500 to 10,000, are prepared by copolymerizing in bulk (A) 10-90% by weight of at least one ester of (meth)acrylic acid and a C 1 -C 20 alcohol, the ester not containing hydroxyl or carboxylic acid groups, (B) 0-50% by weight of at least one olefinically unsaturated monomer containing at least one hydroxyl group, (C) 0-40% by weight of at least one olefinically unsaturated carboxylic acid, (D) 0-40% by weight of (meth)acrylamide or at least one N-substituted derivative thereof and (E) 0-70% by weight of at least one monomer selected from styrene, α-methyl styrene, acrylonitrile, vinyl acetate, vinyl propionate, vinyl alkyl (C 1 -C 8 ) ethers, methacrylonitrile, allyl acetate, vinyl chloride and vinylidene chloride, the percentages totalling 100 and at least one monomer selected from (B), (C) and (D) being copolymerized when a monomer (E) is copolymerized; the polymerization being carried out in a first stage at a temperature of from 100- 150‹ C. with an initiator which decomposes into free radicals below 100‹ C. up to a conversion of 70-90% by weight, and then in a second stage at a temperature of from 130-170‹ C. with an initiator which decomposes into free radicals at a temperature of from 100-170‹ C. up to a conversion of at least 95% by weight. The process can be conducted continuously or batchwise. Monomer (A) is suitably an alkyl or cycloalkyl (meth)acrylate; monomer (B) may be a hydroxyalkyl ester of (meth)acrylic, maleic, fumaric or itaconic acid or a partial allyl or vinyl ether of a polyhydric alcohol; monomer (C) may be acrylic, methacrylic, crotonic, maleic, fumaric or itaconic acid. Initiators for use in the first stage include t-butyl perpivalate and t-butyl peroctoate (many others are also listed) and initiators useful in the second stage include di-t-butyl peroxide, t-butyl hydroperoxide, cumyl hydroperoxide, methyl ethyl ketone peroxide and t-butyl perbenzoate. A polymerization regulator may be present during the polymerization, e.g. n- or t-dodecyl mercaptan, cyclohexene or carbon tetra-chloride. The resins obtained can be reacted or mixed with reactive components such as isocyanates, N-methylol compounds, polycarboxylic acids or anhydrides, polyepoxides and blocked isocyanates. The resins are useful for forming protective or insulating coatings on materials such as metals, porcelain, ceramics, plastics and wood.