Silicone varnish resistant to 200~250 ℃; The coating made with silicone resin as base material, aluminum powder, heat-resistant filler and glass material can withstand 300~700 ℃. But silicone coatings generally need high temperature (150~200 ℃) curing, curing time is long, poor adhesion to the bottom, poor resistance to organic solvents, high temperature when the mechanical strength of the film is not good, the price is more expensive. The silicone resin modified by organic resin can improve its adhesion, curing property and construction property, making it more suitable for the application of coatings, but at the same time, it will reduce the heat resistance of coatings to a certain extent.

 Silicone modified coating
1 Epoxy resin modified silicone coating
Epoxy resin has excellent mechanical properties, electrical properties, chemical resistance, bonding properties, easy molding and low cost, etc. Combined with the characteristics of high temperature resistance, weather resistance, hydrophobicity and high electrical strength of silicone resin, it can produce high temperature resistance and heat insulation coatings with excellent performance. In the process of synthesis of modified silicone resin, the most important problem is the blending of silicone resin and common organic resin. The properties of copolymers are closely related to the compatibility of silicone and organic resins. From the point of view of molecular aggregation state, because these two resins can not achieve effective mixing, into a phase, for heterogeneous blend system, with the extension of time, the system appears phase separation, can not give full play to the excellent performance of the two resins; Therefore, the key of silicone modification is to improve the blend property of resin. Silane coupling agent is a commonly used compatibilizer. Yangde epoxy modified polysiloxane as the base material, adding high temperature and radiation resistant color filler and excellent flame retardant and fire retardant, and N-7 curing agent with GT series of temperature curing high temperature and radiation resistant equipment special fire retardant coating, the coating in 900 ℃ oil flame condition, 1.5h temperature resistance, The temperature of the sample substrate is 300 ℃. Using water-based silicone resin and inorganic sodium silicate solution as the base material, condensation aluminum phosphate as the reaction curing agent, by adding hollow ceramic microspheres and metal aluminum powder and other functional fillers, the heat insulation coating with high temperature resistance of 600 ℃ and remarkable heat insulation effect was prepared.

2 Polyurethane modified silicone coatings
Polyurethane modified silicone resin can be prepared by transesterification of the alkoxy group in the polysiloxane molecule and part of the hydroxyl group in the polyurethane prepolymer. The resin can be cured at room temperature, overcoming the shortcomings of curing silicone coating at 150~250 ℃. The preparation of block copolymer of waterborne polysiloxane and polyurethane by proper chemical synthesis method can maintain the characteristics of wear-resisting, tearing resistance and bending resistance of polyurethane material, and at the same time have the advantages of low temperature flexibility and low surface tension. Wu Di et al. used polyurethane to modify silicone resin, so that the silicone resin has the property of room temperature curing, but still has good heat resistance, weather resistance and electrical insulation and other properties, the prepared film can withstand a variety of acid, alkali, salt and chemical reagent erosion.

3 Acrylic resin modified silicone coating
Acrylic resin is generally chain-shaped linear structure, belongs to thermoplastic material, extremely sensitive to temperature, performance is "hot sticky cold brittle"; In addition, acrylic resin film water resistance, organic solvent resistance is poor; However, silicone modified acrylate can effectively combine the advantages of silicone and acrylate respectively, which not only retains the excellent physical and mechanical properties of acrylic resin, but also improves the heat resistance, solvent resistance and salt spray resistance.