| 摘要 |
1,125,389. Polysiloxane foams. GENERAL ELECTRIC CO. 13 Dec., 1965 [4 Jan., 1965], No. 52893/65. Headings C3C and C3T. Organopolysiloxane foams are prepared by mixing together (A) a nitrogen-containing silicon compound having the structural unit # SiOY, where Y is an amine radical selected from -NR 2 and a heterocyclic amine and is bonded to silicon by a Si-O-N linkage, R being a monovalent hydrocarbon radical, and the remaining valences of the silicon atom are satisfied by -OY radicals, oxygen, R radicals, halogenated R radicals, divalent hydrocarbon radicals and mixtures thereof, (B) a linear organosilicon polymer having a viscosity of at least 1000 cp. at 25‹ C., consisting of units of the formula -Si(R 2 ) 2 -O- and terminal units -Si(R 2 ) 2 -X, where X is hydroxy optionally mixed with up to 50% molar of hydride, and R 2 is defined as R, halogenated R, or cyanoalkyl, (C) a silicon hydride having at least one organic radical per silicon atom, and (D) a hydroxylated material (A) being used in an amount so that the ratio of -OY radicals to -X radicals is at least 1: 3 molar and (C) and (D) are used in proportions of 1% to 75% by weight of B and up to 50% by weight of B respectively. The silicon hydride is preferably a siloxane having Si-H bonds, and suitable hydroxylated materials are water, hydroxylamine and aliphatic alcohols. The foamable mixture may be preserved in an air-tight container without foaming, but will foam upon exposure to atmospheric moisture. It may be foamed in situ to form a covering, e.g. for an electrical component. |
