During the preparation of silicone impregnated varnish, the ratio of the number of organic groups to silicon atoms, the ratio of the number of phenyl groups to organic groups, the hydrolysis temperature, hydrolysis time, condensation time, vacuum degree and other technological parameters are the key factors affecting the properties of silicone resin.
Silicone impregnated paint can be divided into condensation type and addition type according to different crosslinking curing methods.
Condensed silicone impregnation paint is a silicone resin prepolymer containing Si-OH, Si-OR and other groups, under the action of catalyst OR heating further condensation cross linked into solid products.
The added silicone impregnated paint is cross-linked by the hydrosilicification addition reaction between polysiloxane containing Si-VI bond and siloxane containing Si-H bond under the action of catalyst.
Compared with the condensation type, the addition molding has excellent flame retardant, waterproof, thermal oxidation stability and insulation performance, but also has the advantages of no solvent, no low molecular volatilization during curing, can be used for electrical equipment impregnation insulation treatment.
In addition, the application process of adding molded silicone impregnation paint also has the advantages of simple impregnation application process and post-treatment process, easy to realize automation, energy consumption and labor saving.
The choice of catalyst is very important. The coordination compound of platinum metal has high activity and can trigger the addition curing reaction at a lower temperature. It is widely used as a crosslinker for adding molded silicone resins.