| 摘要 |
1,254,254. Room-temperature vulcanizable polysiloxane compositions. DOW CORNING CORP. 4 May, 1970 [19 May, 1969], No. 21337/70. Heading C3T. A room-temperature vulcanizable (RTV) composition comprises (A) a triorganosiloxyterminated polydiorganosiloxane having on average 2-4 vinyl radicals per molecule, the remaining organic radicals being C 1-10 hydrocarbon or halohydrocarbon radicals free of aliphatic unsaturation, and having a viscosity from 100 to 100,000 cs. at 25‹ C., (B) an organosilane RHSiCl 2 , where R is a C 1-10 organic radical as above, providing 0-9-1-1 Si-bound H atoms per vinyl group in (A), (C) a compound containing at least 5 wt. per cent of alkoxy groups which is a silane R b Si(OR<SP>11</SP>) 4-b or a partial hydrolysate wherein R is above and R<SP>11</SP> is a C 1-6 alkyl thereof, providing 0-75-2 alkoxy groups per Cl atom in (B), and (D) an organic peroxide in amount 0-1-10 wt. per cent of (A). It is cured by heating it to 90-175‹ C. for at least one minute, to decompose the peroxide, then exposing it to moist air to obtain a cured elastomer. Conventional fillers e.g. silicas and room-temperature catalysts e.g. organotin salts and titanates may be added. In oxamples (A) polydimethylsiloxanes having methylvinylphenylsiloxane, dimethylvinylsiloxane or methylvinylhexylsiloxane end-units, and optionally 5% methylphenylsiloxane units, or 4 methylvinylsiloxane units with trimethylsiloxane end-units, are mixed with (C) ethyl or hexyl orthosilicate or methyl trimethoxysilane, (B) MeHSiC1 2 , EtHSiCl 2 , PhHSiCl 2 or decyl-HSiCl 2 , and (D) t-butyl perbenzoate, benzoyl peroxide, 2 : 4 - dichlorobenzoyl peroxide, 2 : 5 - bis - (tbutylperoxy)-2 : 5-dimethylhexane or t-butyl peroxide. They are heated at 116-175‹ C. for 5-60 minutes, then cured by exposure to ambient air.
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