Solid silicone resin is a kind of organosilicon polymer material that appears solid at room temperature and forms through highly cross-linking and curing. Its main chain is alternately composed of silicon-oxygen bonds (Si-O-Si), with organic groups such as methyl and phenyl connected to the side chains, forming a typical three-dimensional network cross-linked structure. Different from liquid silicone resin, solid silicone resin has larger molecular weight and higher cross-linking density. It is insoluble in common organic solvents and features more outstanding thermal stability, mechanical strength and electrical insulation. It is an indispensable key category in the high-end organosilicon material system, widely used in high-temperature resistant coatings, electrical insulation, composite bonding, precision electronic packaging and other high-end industrial fields.
The mainstream synthesis of solid silicone resin adopts hydrolysis polycondensation process with alkyl alkoxysilane or alkyl chlorosilane as basic raw materials. Under acid-base catalysis, the raw materials are hydrolyzed step by step in a mixed system of water and inert solvent to generate active silanol intermediates. Then linear and branched prepolymers are gradually formed by heating polycondensation. After solvent removal, high-temperature precuring, crushing and screening, solid powder or block products are obtained. The core of the process is to accurately control the hydrolysis rate, reaction temperature and holding time, and reasonably adjust the ratio of methyl to phenyl groups, so as to customize solid silicone resin products with different hardness, heat resistance and flexibility. Compared with liquid silicone resin, solid silicone resin requires no additional solvent dilution with extremely low VOC and excellent storage stability. It will not agglomerate or deteriorate after long-term storage, suitable for solvent-free green production systems.
This material has irreplaceable comprehensive physical and chemical advantages. It has excellent heat resistance, with long-term service temperature up to 280～350℃ and short-term resistance above 400℃. It does not melt, flow or suffer obvious thermal weight loss under high temperature, and its thermal aging resistance is far better than ordinary epoxy and phenolic resins. Its electrical insulation performance is stable with high volume resistivity and breakdown strength, and the insulation parameters fluctuate slightly under changing temperature and humidity, meeting the strict insulation requirements of H-grade and above motors, transformers and electrical appliances. At the same time, it features excellent weather resistance, acid and alkali corrosion resistance, low moisture absorption, high hardness and wear resistance. It will not pulverize or crack after long-term outdoor use, adapting to complex corrosive working conditions.
With the upgrading of high-end manufacturing and green chemical industry, the process of solid silicone resin is iterating towards low impurities, high cross-linking and solvent-free. By optimizing the catalytic system and purification process, the content of metal ions and volatile impurities is greatly reduced to meet the high purity requirements of semiconductors, new energy electronics and other fields. Through group modification and cross-linking structure regulation, the rigidity and toughness are further balanced, solving the shortcomings of high brittleness and weak impact resistance of traditional solid silicone resin. With stable and reliable comprehensive performance, solid silicone resin has become the core substrate for high-temperature resistant, high-insulation and long-life industrial products, continuously supporting the upgrading of high-end equipment and new material industry.