The silicone rubber development market has shown steady growth in recent years. As a globally important industrial material, silicone rubbers are widely used in a number of fields due to their excellent resistance to high temperature, low temperature, aging, insulation, and environmental protection. In the future, with the development of science and technology and industrial upgrading, the application areas of silicone rubber will be further expanded, and the market demand will be more vigorous. What kinds of silicone rubber?
Silicone rubber is the largest number of silicone versatile material in a class, by a variety of dichlorosilane through hydrolysis, polycondensation, and an element of organic elastomers. It can be divided into heat vulcanization type (high-temperature vulcanization silicone HTV), and room temperature vulcanization type (RTV), of which the room temperature vulcanization type is divided into polycondensation reaction type and addition reaction type. High-temperature silicone rubber is mainly used in the manufacture of a variety of silicone rubber products, while room-temperature silicone rubber is mainly used as an adhesive, potting material, or mold. The largest amount of hot vulcanized type, hot vulcanized type and sub-methyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ, the amount and the most popular product brands), methyl vinyl phenyl silicone rubber PVMQ (low temperature, radiation resistance), and other fluoro-silicone rubber, and so on.
The following three aspects of silicone rubber and its applications:
- Additional molding liquid silicone rubber
- HTV high-temperature vulcanized silicone rubber
- How to make silicone rubber perform better?
1. Additional molding liquid silicone rubber
LTV is a kind of LIMS liquid injection molding silicone rubber of LSR. The composition and vulcanization of additive molding liquid silicone rubber-LTV consists of vinyl silicone oil, hydrogen-containing silicone oil, platinum catalyst, reinforcing filler, and additives.
XJY-707 Hydride terminated Polydimethylsiloxane
It can be synthesized through the silicone-hydrogen addition reaction of copolymer polymers due to the molecular structure containing active hydrogen atoms and can be made into a series of active silicone oils. It can be used as a chain extender for liquid silicone rubber.
XJY-711 Hydrogen Terminated Methylhydrogensiloxane /Dimethylsiloxane Copolymer
It is a colorless transparent liquid, that can be applied as a crosslinking agent of silicone rubber.
XJY-8206N Methyl Vinyl MQ Silicone Resin + Vinyl Polydimethylsiloxane
It is a colorless transparent liquid resin with methyl and vinyl consisting of vinyl MQ silicone resin and vinyl silicone oil, which can be used for LSR liquid additive molding silicone rubber.
Vulcanization mechanism
（1）Because organic nitrogen, phosphorus, sulfur, and tin will make the catalyst Pt poisoning, affecting the vulcanization, the vulcanization test should be carried out before use.
（2）Neoprene and other synthetic rubbers, sulfur-containing compounds, soft PVC, amine-cured epoxy resin, PVC insulating tapes, turpentine fluxes and so on will hinder the curing, and they can not be used at the same time.
（3）Moisture and humidity will also affect the vulcanization, please store in a dry place.
(2) Applications of LTV
- Low-strength type is mainly used for coating semiconductor electronic components, and potting materials (with shell), to achieve insulation, moisture, dust, and shock, and improve the performance of the purpose of stabilizing parameters, but it also can be formulated with a variety of paper isolation agent.
- It is a high-strength type with good mechanical properties, and it can be used as electronic components without shell encapsulation materials.
- Good adhesion can be used as semiconductor devices within the protective coating, and mixed with silver powder can be used as a bonding conductive adhesive.
- Aviation-type highly transparent materials can make bulletproof glass and aviation bonding agents.
- The medical types used in plastic surgery, saddle nose orthopedics, and atrophic rhinitis treatment; are beauty; and artificial lenses.
- Filled type for flame retardant potting adhesives, foam adhesives, anticorrosive adhesives, coatings, and inks.
- Liquid injection molding-LIMS buttons, pacifiers, etc.
- One-component adhesives, coatings, and inks.
2. HTV high-temperature vulcanized silicone rubber
Due to the poor mechanical properties of HTV raw rubber, it is necessary to add the following components: reinforcing agent: silica; structure control agent; filler; coloring agent: a variety of pigments to do the color paste; a variety of additives; vulcanizing agent: peroxide or addition vulcanization.
Si atom is larger than the C atom, -Si-O-Si- is a spiral structure, the organic group outward, so that the intermolecular force is small, the vulcanized rubber strength is very low, must be added filler reinforcement, otherwise it can not be used.
(1) Electrical properties
Silicone rubber has excellent electrical insulation volume resistance: 101414 ~ 1016Ω.m, in a wide range of temperatures and frequencies in the field, it can maintain stable electrical properties. In addition, even if it is immersed in water, its electrical insulation properties will not decline; therefore, it is most suitable for insulating materials.
(2) Thermal conductivity
Silicone's thermal conductivity than the general coefficient of organic rubber, silicone rubber in the addition of a large number of inorganic fillers can improve the thermal conductivity of silicone rubber, making it work at extreme temperatures these materials can be used in heat sinks and heating rollers.
(3) Steam resistance
Even if immersed in water for a long time, the water absorption of silicone rubber is only 1%; and the mechanical strength and electrical properties will not be affected by almost any (whether cold water, warm water, boiling water, almost no change). However, in the 150 ℃ high-pressure steam environment, the silicone will degrade, and the performance will decline. By improving the formula, selecting the vulcanizing agent, extending the time of the second addition of sulfur, and other measures to improve the steam resistance, but also to develop products with particularly high resistance to steam, and hot water resistance.
(4) Oil, solvent, and chemical resistance
The oil resistance of silicone rubber in a 100℃ environment is slightly worse than that of nitrile rubber and neoprene rubber. At >100℃, silicone rubber is able to exert more excellent oil resistance. Silicone rubber is hardly eroded by polar solvents and weak acids and alkalis, but it will be dissolved in non-polar solvents, but not dissolved, and can be restored to its original state by removing the solvents. Silicone rubber is not resistant to strong acids and alkalis. Solvent chemicals on the silicone rubber to produce swelling, softening, strength loss, and other phenomena, different types of solvents on the impact of silicone rubber is not the same. It can be used for medical devices and making molds.
(5) Compression permanent deformation
Organic rubber at room temperature in the compression permanent deformation is small, but with the temperature change will increase significantly. Silicone rubber in -60 ~ 250 ℃ within the compression permanent deformation is stable, that is to say, silicone rubber in the very temperature used than organic rubber is good. Bending fatigue: silicone rubber bending fatigue resistance is not better than organic rubber. Measures must be taken to develop 8 ~ 10 times the fatigue resistance of the species, it can be used in keyboards and conveyor parts. Strength: at room temperature, the strength of silicone rubber is lower than organic rubber, but at high temperatures, the strength of the retention rate is higher, and the strength is better than organic rubber. Silicone rubber tear strength is low, only to improve the synthesis of the base rubber process as well as mixing rubber filler, the crosslinking agent can be prepared to tear strength of 30 ~ 50 kN / m of the high-strength type of products, suitable for reverse cone molds and large molding products forming materials used.
3. How to make silicone rubber perform better?
The characteristics of silicone elastomers rubber are silicone (polydimethylsiloxane) molecular structure to siloxane bond-based is a very stable structure, so compared with ordinary organic rubbers, silicone compounds have many beneficial properties, such as temperature resistance（low temperatures, electrical insulation, chemical stability. In addition, because the methyl group on the outside of the helical structure can rotate freely, silicones are able to exhibit many unique surface properties, such as water resistance and mold release. How to improve the competitiveness of products?
XJY Silicones is one of the leading silicone MQ resin and VMQ silicone manufacturers in China, with more than 30 years of R&D and manufacturing experience in the silicone industry and more than 15 related patents and technical support to produce silicones. Our silicone raw material products can meet the needs of the silicone rubber field and support the provision of diversified silicone products and customized solutions.
