| 摘要 |
1408154 Foamable and cross-linkable ethylene polymers DOW CORNING Ltd 20 Feb 1973 [29 Feb 1972] 9265/72 Heading C3C A foamable and cross-linkable (in the presence of water) composition comprises (1) an ethylene homopolymer or copolymer with a minor molar proportion of propylene, butylene and/or hexene-1, the polymers having in the molecule chemically bonded silyl groups of formula -SiR n X 3-n ,where R is a monovalent hydrocarbon radical, X is an alkoxy or alkoxyalkoxy radical having less than 6 C atoms, or an oximo radical having less than 14 C atoms (i.e. of general formula -ON=Y, where Y is R<SP>1</SP> 2 C= or where R<SP>1</SP> is a monovalent hydrocarbon radical which may be halogenated, and R<SP>11</SP> is a divalent and R<SP>11</SP> is a olivalent hydrocarbon radical which may be halogenated hydrocarbon radical which may be halogenated, Y having less than 14 C atoms), and n is 0, 1 or 2; (2) a blowing agent; and (3) a siloxane condensation catalyst. The polymers may be made by grafting the ethylene polymer with a silane of formula CH 2 =CHSiR n X 3-n , where R, X and n are as above. The composition is foamed and cross-linked by exposing it to a temperature at which the blowing agent is activated and to water. In the examples polyethylene was grafted with vinyltrimethoxysilane and the polymer was then mixed with azodicarbonamide, sodium bicarbonate or ammonium carbonate as blowing agent, dibutyltin dilaurate as catalyst, together with zinc oxide and stearic acid, the mixtures were then either milled into a sheet and then foamed in a mould, or extruded to form a foamed rod, and the foams were then finally treated with water to effect or promote cross-linking. |
