①the RTV-2 molding silicone rubber with good operating performance

　　② better fluidity for silicone rubber and easy operation for low viscosity

　　③ the smaller the shrinkage, the better

　　④ good tension for silicone rubber

　　⑤ the silicone rubber mold should not deform

　　⑥ the hardness of the silicone rubber should be adapted to the products

　　⑦ high-temperature resistance, high form turnover frequency, the use life as long as possible, acid and alkaline resistance, and ageing resistance.