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Brief Introduction of Silicone Resin

Nov 13, 2019

Introduction to silicone resin

  Silicone resin

    A polymer comprising a main chain of silicon or oxygen atoms, generally having other hydrocarbon groups attached to the silicon atom. Silicone resin has excellent water resistance and temperature resistance (-100 °F to +600 °F).

Silicone resin for its use

    As a insulating varnish (including varnish, enamel, paint, impregnating varnish, etc.) impregnated H-class motor and transformer coil, and used to impregnate glass cloth, glass fiber and asbestos cloth to make motor casings, electrical insulation windings, etc. [2]

    Bonding mica with silicone insulating varnish can produce a large area of mica sheet insulation material, which is used as the main insulation of high voltage motors.

    In addition, silicone resin can also be used as heat-resistant and pressure-resistant anti-corrosion coatings, metal protective coatings, waterproof and moisture-proof coatings for construction projects, mold release agents, adhesives and secondary silicone plastics for electronic, electrical and national defense. Industrial.

Silicone resin characteristics

1, weather resistance

Weather resistance is one of the main characteristics of silicone resins and is therefore widely used as a base for weathering coatings. The easiest way to test the weather resistance of a paint film is to expose the test piece coated with silicone resin to the outside, and observe the change in gloss or color of the coating and the cracking condition. However, due to the amount of sunlight received by the test piece, temperature changes, rain, snow, wind, frost attack, free dust in the air, and pollution of various chemical substances, it is difficult to have strict standards. It is difficult to compare and analyze. In addition, the cycle of obtaining results is longer (in years), so the use of this method has gradually decreased. Now, the accelerated weathering test machine is used to obtain weather resistance data.

Under accelerated test conditions, the gloss of the coating is maintained at 60%, the alkyd resin coating is 250h, and the alkyd resin coating containing 30% (mass fraction) of siloxane is 750h, containing 50% (mass fraction) of siloxane. The alkyd resin coating was 2000h, and after the urethane coating passed 3000h, the gloss retention rate was still higher than 80%. Among the many factors that can cause the aging of the coating, the irradiation of sunlight, especially ultraviolet rays, is the main cause of the decrease in gloss and surface pulverization of the coating. It is known that the light in the wavelength domain of the spectral distribution of the surface of the earth is very sensitive, which is the source of poor weather resistance of organic resins. It is known that methyl siloxane hardly absorbs ultraviolet light, and siloxane containing PhSiO1.5 or Ph2 SiO chain also absorbs only light below 280 nm (including a small amount of ultraviolet light), so the effect of sunlight on silicone resin Smaller, this is the main reason for the excellent weatherability of silicone coatings.

2, mechanical properties

The requirements for the mechanical properties of silicone depend mainly on the application. Silicone resins used as electrical insulating varnishes, coatings and adhesives are concerned with hardness, elasticity, thermoplasticity and adhesion. The hardness and elasticity of the silicone paint film can be varied over a wide range by adjusting the molecular structure of the resin. When the content of trifunctional or tetrafunctional link is higher, that is, the higher the crosslink density, a film with high hardness and low elasticity can be obtained; the introduction of a large sterically hindered substituent can improve flexibility and thermoelasticity. It is the reason why the flexibility and thermoplasticity of methylphenyl silicone are superior to those of methyl silicone. Therefore, silicone resin does not need to use a special plasticizer, but the proper combination of soft and hard silicone resin can meet the plasticity requirements. When used as a certain coating, the hardness of the pure silicone coating film is insufficient, and the thermoplastic is sufficient; if an organically modified silicone resin is used, it is easy to solve this contradiction. Pigments and catalysts can also affect the hardness and elasticity of silicone resins. Pigments have the effect of accelerating the oxidation of silicone paint films and converting them into harder silica glass. Using a low activity catalyst, since the condensation reaction is incomplete, only a soft coating can be obtained; conversely, a highly active catalyst (such as a compound such as Pb, Al, etc.) can be used to obtain a hard and brittle coating, but some catalysts (such as titanium) The acid ester can effectively increase the hardness of the coating without seriously reducing the elasticity. Silicone has good adhesion to iron, aluminum, silver, tin, glass and ceramics, but it has poor adhesion to copper, especially after high temperature and long-term heat aging. There is an accelerated thermal cracking reaction of silicone. The adhesion of silicone grease to organic materials such as plastics, silicone rubber, etc. depends mainly on the surface energy of the latter and compatibility with silicone. The lower the surface energy and the less compatible the material, the harder it is to bond. The adhesion of the silicone resin to the difficult-to-bond substrate can be improved to some extent by the treatment of the surface of the substrate (including sanding and priming), especially by introducing a tackifying component into the silicone resin.


Contact:Sharon Song(Sales manager)

Zhejiang Runhe Organosilicone New Material Co.,Ltd(Factory)

Zhejiang Runhe Chemical New Material Co.,Ltd(Exporter)


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