| 摘要 |
An improved process for preparing adhesive repellent coatings is provided. The process includes the steps of: applying to the surfaces which are to be rendered adhesive repellent, an aqueous emulsion containing (1) diorganopolysiloxanes having Si-bonded vinyl groups in their terminal units, (2) organopolysiloxanes having at least 3 Si-bonded hydrogen atoms per molecule ¢preferably wherein the organopolysiloxanes (2) are present in an amount of 1 gram equivalent of Si-bonded hydrogen for each 0.3 to 0.8 gram molecule of Si-bonded vinyl groups in the diorganopolysiloxanes (1)!, and (3) catalysts (known per se) which promote the addition of Si-bonded hydrogen to vinyl groups, present in a catalytic amount preferably, where the catalyst is a platinum-containing compound of from 0.001 to 0.02 per cent by weight based on the weight of the diorganopolysiloxanes (1), and thereafter cross-linking the polysiloxanes (1). The improvement involves the step of mixing the catalyst (3) with the diorganopolysiloxanes (1) prior to the addition of water, preferably where the catalyst (3) is mixed with at least one-half of the total diorganopolysiloxanes (1) in the absence of a dispersing agent and water to form a homogeneous mixture and thereafter the resultant mixture is mixed with a dispersing agent and water. By this improvement, the solutions are more stable. Since the aqueous solurions can be preserved over a long period of time and still produce coatings as good as those obtained from freshly prepared emulsion, optimum utilization of continuously operated coating devices is achieved without migration of the repellent coatings. The coatings so prepared may be used as separating, cover and lining papers, boards, films and cloths. |
