The Difference Between Silicone Rubber and Silicone Resin

Silicone rubber (English name: Silicone rubber) is divided into heat vulcanized type (high temperature vulcanized silicone HTV) and room temperature vulcanized type (RTV). Among them, the room temperature vulcanized type is further divided into condensation reaction type and addition reaction type.

High temperature silicone rubber is mainly used to manufacture various silicone rubber products, while room temperature silicone rubber is mainly used as adhesive, potting material or mold. The heat vulcanized type has the largest dosage. The heat vulcanized type is further divided into methyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ, the largest dosage and product brand), methyl vinyl phenyl silicone rubber PVMQ (resistant to low temperature and radiation), and others include nitrile silicone rubber, fluorosilicone rubber, etc.

Silicone resin, scientific name polysiloxane resin (English name: Silicone resin) is a polyorganosiloxane with a highly cross-linked network structure. It has the dual characteristics of organic resin and inorganic material. Silicone resin has unique physical and chemical properties.

Classification of silicone resin Silicone resin is a cross-linked semi-inorganic polymer with silicon-oxygen-silicon as the main chain and organic groups connected to silicon atoms. It is produced with the direct method of silicone monomer. Silicone resin has outstanding weather resistance, which is beyond the reach of any organic resin. Even under strong ultraviolet radiation, silicone resin is resistant to yellowing.

Silicone resin adhesives and organic silicone adhesives can be divided into adhesives based on silicone resin and adhesives based on silicone rubber according to the source of raw materials. The former is mainly used for bonding metals and heat resistance. Silicone resin has good bonding performance for metals such as iron, aluminum and tin, and is also easy to bond to glass and ceramics, but has poor adhesion to copper. Organic silicone adhesives based on pure silicone resin.

Characteristics:

Silicone rubber has excellent heat resistance, cold resistance, dielectric properties, ozone resistance and atmospheric aging resistance. The outstanding performance of silicone rubber is its wide operating temperature range, which can be used for a long time at -60℃ (or lower temperature) to +250℃ (or higher temperature). However, the mechanical properties of silicone rubber, such as tensile strength and tear strength, are relatively poor. Its physical and mechanical properties are not as good as most synthetic rubbers at room temperature. In addition, except for nitrile silicone and fluorosilicone rubber, general silicone rubber has poor oil resistance and solvent resistance. Therefore, silicone rubber is not suitable for occasions under ordinary conditions, but it is very suitable for many specific occasions.

Organic silicone resin is mainly used as: insulating varnish (including varnish, enamel, color paint, impregnation paint, etc.) to impregnate H-class motors and transformer coils, and to impregnate glass cloth, glass cloth silk and asbestos cloth to make motor casings, electrical insulation windings, etc. Using organic silicone insulating varnish to bond mica can produce large-area mica sheet insulation materials, which are used as the main insulation of high-voltage motors.

In addition, silicone resin can also be used as heat-resistant and weather-resistant anti-corrosion coatings, metal protective coatings, waterproof and moisture-proof coatings for construction projects, release agents, adhesives, and secondary processing into silicone plastics for use in the electronics, electrical and defense industries, as semiconductor packaging materials and electronics and electrical silicone resins can be roughly divided into several categories according to their main uses and cross-linking methods, such as silicone insulating varnishes, silicone coatings, silicone plastics and silicone adhesives.

Silicone resins can include small molecule silicone compounds, and the molecular weight does not have to be very large. Silicone rubber must be a polysilane with a certain molecular weight and a rubbery state.

Silicone resin coatings have many disadvantages: poor film-forming properties, including high curing temperature and long time, inconvenient large-area construction, and poor adhesion of the coating to the base layer. Fluorination modification is mainly to increase the solvent resistance, oil repellency (anti-stickiness) and reduce the surface energy of silicone resins. The critical surface tension of silicone resins is lower than that of other resins, but higher than that of fluororesins.