Overview of Formulation Technology of Silicone Pouring Sealant


Background


There are many kinds of filling materials, but now most of them are synthetic polymers. Among them, epoxy resin, polyurethane elastomer and silicone polymer are the most widely used polymers. Facing the problems of moisture resistance, heat resistance and internal stress, there are some difficult problems in the application of polyurethane, such as soft surface, easy foaming, inadequate curing and brittle curing at high temperature. Under harsh working conditions, polyurethane filling materials are often difficult to meet the requirements of moisture, heat, aging and high and low temperature resistance. Silicone polymer materials are widely used for the sealing protection of electronic and electrical components because of their special structure of silicon-oxygen bond main chain, unique weather resistance, aging resistance, excellent high and low temperature resistance, good hydrophobic mechanical properties, electrical insulation, etc. It belongs to other materials, such as the application technology of low melting point glass powder, to be shared separately.


2. Silicone sealant


Composition and Classification of 2.1 Silicone Pouring Adhesive


Silicone sealant is composed of silicone resin, crosslinking agent, catalyst and thermal conductive material. Silicone rubber sealant can be divided into room temperature vulcanized silicone rubber, two-component formed silicone rubber sealant (ARC silicone rubber) and two-component condensed silicone rubber sealant (RTV silicone rubber) according to molecular structure and cross-linking method.


ARC silicone rubber has no release of small molecule, easy control of cross-linking structure, shrinkage rate below 0.2%, electrical properties, elasticity and other advantages over RTV silicone rubber, and superior technological properties, which can be cured at room temperature and in a short time after heating. Therefore, ARC silicone rubber sealant is recognized as a new type of material for electronic industry with great development prospects at home and abroad.


2.2 Dual Component Additive Formed Silicone Rubber Sealant


The common two-component silicone rubber filling glue is composed of vinyl-terminated silicone oil as base glue, hydrogen-containing silicone oil as cross-linking agent and aluminium trioxide (A l2O3) as thermal conductive filler. Methacryloxypropyl trimethoxysilane (KH570) can be added as coupling agent and platinum catalyst (PL-2600) as catalyst.






Vinyl silicone oil is used as the base glue and anhydrous transparent silicone powder 507 containing amphilene is used as the main functional filler. The anti-sinking, thixotropy and thickening functions of AMINE Q702 nanometer light silicon powder can be added to reduce the weight of base rubber materials and the proportion of finished products. Appropriate alcohol diluted organic solvents can be added during the experiment.


From Guangdong Qichen