Heat shrinkable silicone rubber is introduced-Hong...

Heat shrinkable silicone rubber is introduced         Heat shrinkable silicone rubber is a kind of silicone rubber in the development of new varieties of sixty, it has high resistance to high temperature, special general silicone rubber electric properties of moisture resistance and excellent, also has a useful simple method at 150 ℃ heating contraction of about 50%, fastening to the characteristics of the object on the coated, operation simple and rapid, and convenient site construction, are widely used in various electronic components, instrument and meter insulation, protection and connection.        Silicon rubber is an elastic body, force can cause deformation, out external deformation basically eliminated, it itself has no heat shrinkage. In order to make the silica gel with heat shrink, needs to have the higher melting temperature or the softening temperature of the thermoplastic resin with. Therefore, heat shrinkable silicone rubber composition is the most basic of silicone rubber and thermoplastic resin, the thermal contraction function mainly depends on the interaction between silicone rubber and thermoplastic resin elasticity supporting force.         When using the heating method, can make the composition of thermoplastic resin by glass into a viscous state, in this state, applying external force can make the heat shrinkable silicone rubber elongation; then in keeping the deformation conditions, the melting temperature rapidly cooled to resin under, will make the resin the viscosity and into the glass state. At this time, glass resin support with silicone rubber elasticity to counterbalance each other, when the two balance or supporting force is larger than the elasticity, the deformation is preserved, usually the extension deformation keep called stereotypes.        It is not difficult to see that, in the shaping stage is the supporting force of resin to play a primary role in. But when this setting in the absence of external force, again heated to melting or softening temperature resin on resin again, glassy into viscous state, the resin also lost the support strength, enter to rubber elastic stage. In the rubber elasticity under the action of heat shrinkable silicone rubber, shrinkage is intact, that gives heat shrinkable silicone rubber properties. According to this principle, the ordinary rubber silicone rubber and thermoplastic resin prepared by extrusion, molding, molding, curing, made of semi-finished products, and then semi-finished products are heated to a plastic state of resin, the expansion force applied to a certain size, and in maintaining the expansion state cooling to room temperature, out after the external force, due to the resin is solid, the expansion of the size remains down, get heat shrinkable silicone rubber products. When in use, the heat shrinkable silicone rubber products set to be coated fabric, and then heated to resin is in plastic state, because the silicon rubber elasticity, products to shrink in coated material, connection, protection insulation effect.       Can cooperate in silicone rubber thermoplastic polyethylene, polystyrene and its copolymers and copolymers, polyacrylate, low molecular weight silicone resin, poly organic siloxane, block silicone resin, silicone phenylene silicone, pvdf. The Shanghai rubber products of poly silicon phenylene silicone as thermoplastic resin, light chemical industry research institute uses poly organic siloxane as thermoplastic resin, have developed into heat shrinkable silicone rubber.        Heat shrinkable silicone rubber mixing process and ordinary silicon rubber mixing process, due to join the plastic resin, need to increase a thermal mixing. The main products are pipe forms are used. By extrusion sulfuration, ordinary silicon rubber was finished, and for heat shrinkable silicone rubber is still semi-finished products, the need for expansion forming. Expansion forming process by heating, expansion, cooling and shaping consists of three processes. There is no strict requirements for heating and cooling way, one can use electric, steam or oil heating, water or air cooling; and the expansion of the way are many and varied, but can be broadly divided into the die tip expansion and continuous expansion of die two process. The latter process is advanced, creating favorable conditions for industrial chemical production. Chenguang Research Institute of chemical industry developed by continuous expansion forming process of short tube, the process is simple in equipment, pipe expanding speed, low rejection rate, the finished tube with better strength, heat shrinkage rate of the finished pipe can be maintained at more than 40% in six months, axial shrinkage in 20%, is a relatively advanced expansion forming process.       Heat shrinkable silicone rubber in the cable, motor and other products increasingly wide range of applications. Cable after heat shrinkable silicone rubber tube coating, can make full use of silicon rubber insulation, excellent weathering resistance and other characteristics, expand the scope of the use of cable.