Study On Preparation Technology Of Modified Polysiloxane

Silicone materials are widely used in industry,agriculture and science and technology because of their excellent properties.For the related application in the polyurethane demoulding and foaming field,we designed and synthesized two modified polysiloxane（modified silicone oil）:long chain alkyl modified silicone oil and si-o-c block modified polyether silicone oil.The low hydrogen-containing silicone oil having a hydrogen content of 0.18%was prepared by telomerization of high hydrogen silicone oil,octamethylcyclotetrasiloxane（D₄）,hexamethyldisiloxane（MM）in the presence of macroporous sulfonic acid resin catalyst.The single factor test was carried out to explore the effects of reaction temperature,reaction time and catalyst dosage on the yields of the low hydrogen silicone oil products.The results showed that the optimum conditions for the synthesis of low hydrogen-containing silicone oil were reaction temperature 60°C,reaction time 10 h,catalyst dosage 2%,giving low hydrogen-containing silicone oil yield 90%.After the catalyst was reused 4 times,the product still had a high yield.The synthesis of alkyl siloxane was performed by hydrosilation of low hydrogen-containing silicone oil andα-olefin in the presence of platinum catalyst.By combination of orthogonal design method and single factor test,the influence of the reaction temperature,reaction time,amount of catalyst and other factors on the conversion rate of alkyl siloxane was studied.The preferable reaction conditions for the synthesis of alkyl siloxane were as follows:the reaction temperature was 110°C;the reaction time was4 hours;amount of catalyst was of 15μg/g,and poly（melthylhydrosiloxane）was added dropwise over a period of 45 minutes.The resulting conversion of low-hydrogen silicone oil was up to 87.75%.The Si-O-C type block polyether modified silicone oil was synthesized from the terminal hydrogen silicone oil and polyethylene glycol with alkaline catalysts.The process conditions for producing high polymerization degree block polyether modified silicone oil（n>10）with different catalysts were explored and optimized.The results showed that the optimum synthesis conditions were the reaction temperature 50°C,reaction time 4 h,and solid base catalyst dosage 1%.The molecular weight of block polyether modified silicone oil was 56 000（n>30）and the product had good stability.