The Preparation Of Silicone Foam

Silicone foam is general made up of base gum,foaming agent,all kinds of packing,catalyst,etc.It can foam vulcanization molding after mixing in a short period of time.Silicone foam material has properties such as excellent flexibility,high and low temperature resistance material,physical inert,etc.It has been has been widely used in the national economy and in the daily life.This article focuses on preparation and properties of silicone foam condensation type.By using stannous iso caprylate as catalyst,condensation foam of siloxane such as hydroxy siloxane and hydrogen siloxane were taken place,for the preparation of silicone foam.And the test of SEM and TGA were analyzed.This airticle first discusses the hydrogen release speed in the reaction of different hydroxyl compounds and hydrogen siloxane under the condition of stannous isocaprylate.The experimental results show that,under the same reaction conditions,the reaction rate of different kinds of reactants has very big difference:when the hydroxyl compound is ethanol,with four kinds of hydrogen siloxane order reaction velocity is 1,3,5,7-Tetramethylcyclotetrasiloxane(DH4)>0.25%hydrogen silicone oil>3H,5H-Octamethyltetrasiloxane(D4H2)>1.5%hydrogen silicone oil;When thehydrogen siloxane is DH4,its reaction rate with three kinds of polyol size followed by ethanol>Isopropyl alcohol>hydroxyl-terminated silicone oil(viscosity is 40 mPa.s).Results show that the main factors influencing the reaction speed is steric hindrance of reactants.Based on the above experimental results,with different kinds and proportion of mixture of hydroxyl compounds and hydrogen siloxane mixture as base gum,the flame retardants,aluminum hydroxide,fumed silica and other solid packing were added for the preparation of silicone foam by using stannous iso caprylate as the catalyst.The type and proportion of hydroxyl compounds and the hydrogen siloxane,kind and amount of solid packing,and the dosage of catalyst’s influence on foam and the product performance was discussed.The best formula for the preparation of silicone foam was determined:5.50 to 6.50 g of 80000 mPa.s end hydroxyl silicone oil viscosity,6.00 to 7.00 g of 3000 mPa.s end hydroxyl silicone oil viscosity,5.00 to 6.00 g of 40 mPa.s end hydroxyl silicone oil viscosity,0-1.00 g Ph2Si(OH)2,1.40 to 1.60 g D4H2,0.40 to 0.60 g of 0.25%hydrogen containing the amount of hydrogen containing silicone oil,0.50 to 0.90 g of stannous iso caprylate,5.00 to 9.00 g of 2000-3500 mesh aluminum hydroxide,1.50 to 2.50 g of FR-208 type flame retardant agent and 0.80 to 1.00 g of 6000 mesh fumed silica.Under the condition of this formula,silicone foam was prepared,SEM and TGA analysis was taken place,and its density,average pore diameter and obturator rate was measured.This article also simply discusses the reaction of hydroxyl compounds and hydrogen siloxane under the platinum catalyst condition.Found under the Karstedts platinum catalyst,hydroxyl-terminated silicone oil(viscosity 3000 mPa.s)can react with DH4 to preparate silicone foam;Under the same catalyst and ethanol as foaming agent,the silicon hydrogen addition reaction of the vinyl silicone oil and hydrogen siloxane can also take place,for the preparation of silicone foam.