| 摘要 |
This invention is a method of producing an aqueous latex of crosslinked polydiorganosiloxane. The latex yields an elastomer upon removal of the water. The latex is prepared by homogenizing a mixture of hydroxyl endblocked polydiorganosiloxane; a silane of the formula Ra'Si(OR3)4-a where R' is a monovalent hydrocarbon radical of up to 12 carbon atoms, R3 is an alkyl radical of 1 to 6 carbon atoms, a partial hydrolyzate, or mixture of silane and hydrolyzate, and a is 0 or 1; a surface active anionic catalyst of the formulae R2C6H4SO3H wherein R2 is a monovalent hydrocarbon radical of at least 6 carbon atoms, R2OSO2OH, or <IMAGE> wherein R4 is H or R2; and water. The resulting emulsion is maintained at a temperature of 15 DEG to 30 DEG C. for at least 5 hours at a pH of less than 5 until a crosslinked polymer is formed, then this emulsion is admixed with base to a pH of greater than 7. The resulting emulsion is reinforced by adding greater than 1 part by weight of colloidal silica sol or silsesquioxane to yield a latex. Removal of water from the latex results in a reinforced elastomer. This method yields a latex which can be applied and dried immediately after mixing to yield an elastomer. |
