Silicone rubber is a special synthetic elastomer, which is made of linear polysiloxane mixed with reinforcing filler and vulcanized under heating and pressure. It perfectly balances mechanical properties and chemical properties, so it can meet the requirements of many demanding applications today.
Silicone rubber performs well in the following fields:
High and low temperature stability
Inert (tasteless and odorless)
Transparent and easy to color.
Wide hardness range, 10-80 Shore hardness.
chemical resistance
weather ability
airtightness
Electrical property
resistance to compression
In addition to the above excellent properties, silicone rubber is particularly easy to process and manufacture compared with traditional organic elastomers. Silicone rubber is easy to flow, so it can be molded, calendered and extruded with low energy consumption. Easy processing means high production efficiency.
Silicone rubber can be provided in the following forms:
Rubber compound: This ready-made material can be colored and catalyzed according to your processing equipment and end use.
Substrate: This silicone polymer also contains reinforcing fillers. Rubber-based materials can be further mixed with pigments and additives to form rubber compounds to meet your color and other manufacturing requirements.
Liquid Silicone Rubber (LSR): This two-component liquid rubber system can be pumped into appropriate injection molding equipment and then thermally cured into molded rubber parts.
Fluorosilicone rubber compound and base material: fluorosilicone rubber maintains many key properties of silicone, in addition, it also has superior chemical resistance, fuel resistance and oil resistance.
Second, silicone rubber.
Silicone material is mainly composed of silicone oil, silicone rubber, silicone resin and silane coupling agent. Silicone rubber is the largest and most widely used product in silicone. Its main component is linear polysiloxane with high molar mass. Because the Si-O-Si bond is a basic bond type, silicon atoms are mainly connected with methyl groups, and a very small amount of unsaturated groups are introduced into the side chain, so the intermolecular force is small, the molecules are in a spiral structure, and the methyl groups are arranged outward and can rotate freely. Therefore, vulcanized silicone rubber has excellent characteristics such as high and low temperature resistance, weather resistance, hydrophobicity, electrical insulation and physiological inertia, and is widely used in national defense, military industry, medical and health care, industrial and agricultural production and people's daily life.
Main properties and applications of 1. silicone rubber
According to its curing temperature, silicone rubber can be divided into two categories: high temperature (heating) curing type and room temperature curing type. High temperature rubber is mainly used to manufacture various silicone rubber products, while room temperature rubber is mainly used as adhesive, potting material or mold.
(1) Hot vulcanized silicone rubber (HTV)
Hot vulcanized silicone rubber (HTV) is the most important product in silicone, and methyl vinyl silicone rubber (VMQ) is the most important product in HTV, commonly known as high temperature rubber.
Methyl vinyl silicone rubber (raw rubber) is a colorless, tasteless, non-toxic and mechanical impurity-free gel. Raw rubber is mixed with appropriate additives such as reinforcing agent, structure control agent, vulcanizing agent, etc. according to needs, and then heated, molded or extruded, and then vulcanized in two stages to make various products. Its products have excellent electrical insulation, strong arc, corona and electric spark resistance, good waterproof, moisture-proof, impact and vibration resistance, physiological inertia, air permeability and other properties.
It is mainly used in aviation, instruments, electronic appliances, navigation, metallurgy, machinery, automobiles, medical and health departments, and can be used as sealing rings, gaskets, pipelines and cables of various shapes, as well as release agents for human organs, blood vessels, breathable films, rubber molds and precision casting.
(2) room temperature vulcanized silicone rubber (RTV)
Room temperature vulcanized silicone rubber generally includes condensation type and addition type.
Addition room temperature adhesive is an elastomer with linear polysiloxane with vinyl as basic adhesive and hydrogen-containing siloxane as cross-linking agent. In the presence of catalyst, cross-linking reaction occurs at room temperature to medium temperature. It has good heat resistance, hydrophobicity and electrical insulation. At the same time, due to the introduction of active end groups, it has excellent physical and mechanical properties, especially tensile strength, relative elongation and tear strength. Suitable for radiation vulcanization, peroxide vulcanization, addition vulcanization and other vulcanization methods, widely used in heat-resistant, moisture-proof, electrical insulation, high-strength silicone rubber products and so on.
Condensed RTV silicone rubber is characterized by condensation reaction between silicon hydroxyl group and other active substances, which can be crosslinked into elastomer at room temperature. Products are divided into one-component packaging and two-component packaging. One-component room temperature vulcanized silicone rubber (RTV- 1 rubber for short) is one of the main products of condensed liquid silicone rubber. It is usually made of basic polymer, crosslinking agent, catalyst, filler and additives. The product is packed in a sealed hose, extruded when in use, and can be vulcanized into elastomer by itself after contacting with air, which is very convenient to use. Vulcanized rubber can be used for a long time in the temperature range of (-60 ~+200℃), and has excellent electrical insulation, chemical stability, water resistance, ozone resistance and weather resistance, and good adhesion to various metal and nonmetal materials. It is mainly used for coating various electronic components and electrical equipment, and the packaging material plays the role of insulation, moisture-proof and shock-proof; As a surface protection material for semiconductor devices; It can also be used as sealing filler and elastic adhesive.
Two-component room temperature vulcanized silicone rubber (RTV-2 rubber for short) is not as convenient to use as RTV- 1 rubber, but its component ratio is varied. A variety can obtain vulcanized products with various specifications and properties, and can also be deeply vulcanized, so it is widely used for insulation, packaging, caulking and sealing in industries such as electronic appliances, automobiles, machinery, construction, textiles, chemicals, light industry and printing. In addition, RTV-2 has excellent demoulding property, so it is widely used as a soft mold material for copying and manufacturing cultural relics, handicrafts, toys, electronic appliances, mechanical parts and so on.
One of the typical applications of silicone sealants is the glass curtain wall. The glass and aluminum alloy frame are bonded with silicone structural adhesive as the external wall material, and the expansion joints are sealed with silicone weatherproof adhesive. Other applications include peripheral sealing of aluminum alloy doors and windows and plastic steel doors and windows, flat seam sealing of glass installation and movable slots, sealing of rivets and fixing screws, waterproof sealing of sanitary ware in kitchen, bathroom and toilet, and waterproof sealing between countertops, walls and furniture; Sealing of aquarium, ceiling, metal roof, window, counter, partition and color steel plate; Used for waterproof sealing between plates such as high-grade highways.
RTV includes sealants used in aerospace, nuclear power plants, electronics, machinery, automobiles and other industries, silicone potting materials used for potting electronic components, and silicone molding compound used as soft mold materials. The demand for these varieties is relatively small and complete, but they are indispensable on many occasions. silicon rubber
Among many synthetic rubbers, silicone rubber is the best. It is odorless and nontoxic, and is not afraid of high temperature and cold. It is "poised" and "face neutral" at 300 degrees Celsius and 90 degrees below zero, and still maintains its original strength and elasticity. Silicone rubber also has good electrical insulation, oxygen resistance and aging resistance, light resistance and aging resistance, mildew resistance and chemical stability. Because of these excellent properties, silicone rubber has been widely used in modern medicine. In recent years, hospitals, scientific research units and factories have successfully trial-produced a variety of silicone rubber medical supplies.
Silicone rubber anti-noise earplugs: comfortable to wear, can block noise well and protect the eardrum.
Silicone rubber fetal head aspirator: easy to operate, safe to use, can be deformed according to the size of fetal head, and the fetal scalp will not be sucked up during aspiration, which can avoid scalp hematoma and intracranial injury and greatly alleviate the pain of dystocia pregnant women during delivery.
Silicone rubber artificial blood vessel: It has special physiological function and can be in close contact with the human body, which is not rejected by the human body. After a certain period of time, it will be completely stable with human tissues.
Silicone rubber eardrum repair subsidy: thin and soft, good smoothness and toughness. It is an ideal material for repairing eardrum, with simple operation and quite good effect.
In addition, there are silicone rubber artificial trachea, artificial lung, artificial bone and silicone rubber duodenum tube. And their effect is very ideal.
With the progress and development of modern science and technology, the application of silicone rubber in medicine will have a broader prospect.
Silicone rubber is a polymer elastic material with both inorganic and organic molecular bonds. Its molecular primary key consists of silicon atoms and oxygen atoms alternately (-Si-O-Si-). The bond energy of silicon-oxygen bond is 370kj/mol, which is much larger than that of ordinary rubber (240KJ/mol), which is one of the main reasons for the high thermal stability of silicone rubber. Silicone rubber has the widest working temperature range (-100 ~ 350 oc) and excellent high and low temperature resistance. In addition, it also has excellent thermal stability, electrical insulation, weather resistance, ozone resistance, air permeability, high transparency, tear strength, excellent heat dissipation, excellent adhesion, fluidity and demoulding. Some special silicone rubbers also have excellent oil resistance and solvent resistance. Application of silicone rubber: it can be used to mold electronic components such as high-pressure wheels; It is used to produce televisions, computers, photocopiers and so on. It is also used as a molding gasket requiring weatherability and durability, a packaging material for electronic components and a protective material for automobile electrical components. It can be used for construction and repair, joint sealing of expressways and joint sealing of reservoirs and bridges. In addition, there are special purpose silicone rubber, such as conductive silicone rubber, medical silicone rubber, foamed silicone rubber, molded silicone rubber, heat shrinkable silicone rubber and so on.
What is silicone rubber?
Silicone rubber is a unique synthetic elastomer, which is made of polymer crosslinked by oxygen and silicon. It perfectly balances mechanical properties and chemical properties, so it can meet the requirements of many demanding applications today.
Silicone rubber performs well in the following fields:
High and low temperature stability
Stability (tasteless and odorless)
Transparent and easy to color.
Wide hardness range, 10~80 Shore hardness.
chemical resistance
weather ability
airtightness
Electrical property
resistance to compression
In addition to the above excellent properties, silicone rubber is particularly easy to process and manufacture compared with traditional organic elastomers. Silicone rubber is easy to flow, so it can be molded, calendered and extruded with low energy consumption. Easy processing means high production efficiency.
Silicone rubber can be provided in the following forms:
Rubber compound-this ready-made material can be colored and catalyzed according to the user's processing equipment and end use.
Base material-This silicone polymer also contains reinforcing fillers. The rubber base material can be further mixed with pigments and additives to form a rubber mixture, which can meet the color and other manufacturing requirements of users.
Liquid Silicone Rubber (LSR)- This two-component liquid rubber system can be pumped into appropriate injection molding equipment and then thermally cured into molded rubber parts.
The fluorosilicone rubber compound and the basic material fluorosilicone rubber keep many key properties of silicone. In addition, it has excellent resistance to chemical fuels and oils.
Silicone rubber is a kind of linear high molecular weight polysiloxane, the molecular weight is generally above 654.38+0.5 million, and its structural form is similar to silicone oil. According to the different organic groups attached to silicon atoms, there are many kinds of silicone rubber, such as dimethyl silicone rubber, methyl vinyl silicone rubber, methyl phenyl silicone rubber, fluorine silicone rubber, nitrile silicone rubber, ethyl silicone rubber and ethyl phenyl silicone rubber.
According to the different vulcanization methods, silicone rubber can be divided into two categories: high temperature vulcanization (thermal vulcanization) silicone rubber and room temperature vulcanization (including low temperature vulcanization) silicone rubber. No matter which type of silicone rubber is vulcanized, there will be no exothermic phenomenon. High temperature vulcanized silicone rubber is a high molecular weight polysiloxane (molecular weight is generally 400,000 ~ 800,000), while room temperature vulcanized silicone rubber has a low molecular weight (30,000 ~ 60,000), and there are one or two functional groups at both ends (sometimes in the middle) of the molecular chain. Under certain conditions (moisture in the air or suitable catalyst), these functional groups can react to form high molecular weight cross-linked structures. Room temperature vulcanized silicone rubber can be divided into condensation type and addition type according to its vulcanization mechanism; According to its packaging methods, it can be divided into two components and one component.
The nature of the silicon-oxygen bond that constitutes the main chain of silicone rubber determines that silicone rubber has advantages that natural rubber and other rubbers do not have. It has the widest working temperature range (-100 ~ 350 oc) and excellent high and low temperature resistance. In addition, it has excellent thermal stability, electrical insulation, weather resistance, ozone resistance, air permeability, high transparency, tear strength, excellent heat dissipation and excellent adhesion. In the service temperature range, silicone rubber can not only maintain certain softness, resilience and surface hardness, but also have no obvious change in mechanical properties, and can resist long-term thermal aging.
Because of the special properties of silicone rubber, it can be used to mold electronic components such as high-voltage wheels, which makes the products have excellent anti-leakage performance and excellent demoulding performance. Used in the production of televisions, computers, photocopiers, etc. , with good heat dissipation and insulation performance. It is also used as a molding gasket requiring weatherability and durability, a packaging material for electronic components and a protective material for automobile electrical components. Silicone rubber can be used in construction and maintenance, joint sealing of expressways and joint sealing of reservoirs and bridges. Silicone rubber can also be used in coatings with strong adhesion, weather resistance, alkali resistance and water resistance. Because of its high temperature resistance, silicone rubber is widely used in manufacturing automobile parts. In addition, there are special purpose silicone rubber, such as conductive silicone rubber, medical silicone rubber, foamed silicone rubber, molded silicone rubber, heat shrinkable silicone rubber and so on.
Silicone rubber performs well in the following fields:
High and low temperature stability
Stability (tasteless and odorless)
Transparent and easy to color.
Wide hardness range, 10~80 Shore hardness.
chemical resistance
weather ability
airtightness
Electrical property
resistance to compression
In addition to the above excellent properties, silicone rubber is particularly easy to process and manufacture compared with traditional organic elastomers. Silicone rubber is easy to flow, so it can be molded, calendered and extruded with low energy consumption. Easy processing means high production efficiency.
Silicone rubber can be provided in the following forms:
Rubber compound-this ready-made material can be colored and catalyzed according to the user's processing equipment and end use.
Base material-This silicone polymer also contains reinforcing fillers. The rubber base material can be further mixed with pigments and additives to form a rubber mixture, which can meet the color and other manufacturing requirements of users.
Liquid Silicone Rubber (LSR)- This two-component liquid rubber system can be pumped into appropriate injection molding equipment and then thermally cured into molded rubber parts.
The fluorosilicone rubber compound and the basic material fluorosilicone rubber keep many key properties of silicone. In addition, it has excellent resistance to chemical fuels and oils.