| 摘要 |
1,262,209. Foamable acrylic resins. ROHM G.m.b.H. 12 Dec., 1969 [27 Dec., 1968], No. 60823/69. Headings C3C and C3P. Synthetic resins capable of foaming when heated comprise (a) a polymer of at least 20 weight per cent of acrylic or methacrylic acid and (b) formamide or a monoalkyl formamide. The resins may be prepared by polymerization in the formamide, or by mixing or swelling preformed polymer therewith. The polymers may also comprise acrylic and methacrylic amides, nitriles and esters, styrene, vinyl esters, maleic anhydride and vinyl pyrrolidone and crosslinking agents. Specified alkyl formamides are N-methyl, N-ethyl and N-propyl formamides. Polymerization may be effected in bags of polymer foil or chambers of glass plates or metal sheets, in the presence of peroxide, azo or redox initiators and optionally silica, asbestos or polymers of acrylic or vinyl esters, vinyl ethers or vinyl acetals. The products may be heated to 170‹ to 300‹ C. to effect simultaneous foaming and imidization of the resins. Examples describe the polymerization of (1-4, 10 and 11) methacrylonitrile and methacrylic acid, together with (5) methyl methacrylate and (6) styrene, (7) acrylonitrile and methacrylic acid, (8) acrylamide and methacrylic acid, (9) methacrylonitrile and acrylic acid and (14) methacrylic acid in the presence of formamide, benzoyl peroxide and t-butyl perpivalate; of (12) methacrylonitrile and methacrylic acid in the presence of monomethyl formamide, benzoyl peroxide and t-butyl perpivalate; and of (13) methacrylonitrile and methacrylic acid in aqueous suspension in the presence of polyacrylic acid, urea, formamide, azodiisobutyronitrile and dilauryl peroxide. |
