| 摘要 |
<p>This invention is a method of producing a latex of crosslinked polydiorganosiloxane. The latex yields an elastomer upon removal of the water. The latex is prepared by homogenizing a mixture of hydroxyl endblockedpolydiorganosil- oxane, less than 75 millimoles of surface active anionic catalyst per kilogram of polydiorganosiloxane where said surface active anionic catalyst is dodecylbenzene sulfonic acid or hydrogen lauryl sulfate, and water to yield an oil-in-water emulsion. This emulsion is them admixed with from 0.5 to 15 parts by weight of an alkoxy silicon compound selected from a silane of the formula R'<Sub>a</Sub>Si(OR<Sup>3</Sup>)<Sub>4-a</Sub> where R' is a monovalent hydrocarbon radical of up to 12 carbon atoms, R<Sup>3</Sup> is an alkyl radical of 1 to 6 carbon atoms, and a is 0 or 1, a partial hydrolyzate of the silane, or mixtures of silane and partial hydrolyzate. The resulting emulsion is maintained at a temperature of about 15 to 30 °C for at least5 hours at a pH of less than 5 until a crosslinked polymer is formed, then the emulsion is admixed with sufficient base to raise the pH to greater than 7. The crosslinked polymer present in the latex is reinforced by adding greater than 1 part by weight of colloidal silica sol or silsesquioxane to the 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 preparation to yield an elastomer.</p> |
