| 摘要 |
The invention comprises organoacyloxydisilanes of the formula (R)n(Si)2(OAc)6-n, where R is an aryl or alkyl radical of 1 to 7 carbon atoms, Ac is a saturated aliphatic acyl radical and n is 1 to 3, and compositions curable to the solid, elastic state upon exposure to moisture which comprise (1) a compound of the above formula and (2) a liquid silanol chain-stopped diorganopolysiloxane in which the organo groups (R1) are monovalant hydrocarbon or halohydrocarbon radicals or cyanoalkyl radicals. The diorganopolysiloxanes have the formula HO(R12SiO)xH, where x is at least 10. The organoacyloxydisilanes may be prepared by reacting an organohalodisilane (R)n(Si)2(X)6-n, where X is halogen, with an acid anhydride or an alkali metal salt of an acid having an Ac radical. When R is alkyl, the organochlorodisilanes are prepared by reacting the organic chloride and heated silicon in the presence of copper. When R is aryl, the organochlorodisilanes are prepared by reacting hexachlorodisilane with an aryl Grignard reagent in e.g. ether. The curable compositions are prepared by simple mixing and cured by exposure to moisture. Suitable Ac groups are: acetyl, propionyl, butyryl, hexoyl, 2-ethylhexoyl, octanoyl, isovaleryl, and stearyl. Suitable R groups are: phenyl, tolyl, xylyl, and alkyl radicals containing from 1 to 7 carbon atoms. Suitable R1 groups are: alkyl, alkenyl, cycloaliphatic, aryl, aralkyl, halogenated monovalant hydrocarbon radicals, and cyanoalkyl.ALSO:Mixtures of certain polysiloxanes and organoacyloxydisilanes are coated on stainless steel plates and allowed to cure by standing at room temperature for 24 hours. The mixtures used are (Ex. 2) a silanol chain-stopped dimethyl polysiloxane and 1,2-dimethyl tetraacetoxydisilane (Ex. 5) a copolymer of diphenylsiloxane units and dimethyl siloxane units, and ethylpentapropionoxy disilane, and (Ex. 6) a silanol chain-stopped dimethylpolysiloxane and phenylpentaacetoxydisilane. In a comparative example, methyl tri-acetoxysilane is mixed with a silanol chain-stopped dimethylpolysiloxane, and the mixture coated on stainless steel and allowed to cure.
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