Introduction: silicone rubber silicone products is the largest output, the most widely used of a large class of products. After curing silicone rubber with excellent resistance to high and low temperature, weather resistance, water-repellent, electrical insulation, physical inertia and other characteristics of the national defense, health care, industrial and agricultural production and people's daily lives has been applied widely. In this paper, the main characteristics of silicone rubber and the future direction of to do a profile.
1. Characteristics and use of silicone rubber silicone rubber polymer molecule profile from the Si-O (Si - O) bond together into a chain structure, consisting mainly of high molecular weight linear polysiloxane. As the Si-O-Si bond is the composition of the basic bond type, the main connection methyl silicon atom, the introduction of a very small amount of side-chain unsaturated group, the intermolecular forces is small, spiral-shaped molecular structure of methyl outward order and the freedom to rotate, making the silicone rubber than ordinary rubber has better heat resistance, electrical insulation, chemical stability. A typical silicone rubber that is formaldehyde poly siloxane, with a spiral-shaped molecular structure, intermolecular forces of its small, so it has good elasticity, while pointing outside the formaldehyde-based spiral can rotate freely, thereby silicone rubber has a unique surface properties, such as the hydrophobic nature and surface anti-sticking. The following table lists the main characteristics of silicone rubber and uses. Heat resistance: silicon rubber has a much better than ordinary rubber heat resistance, can be almost 150 degrees without ever using performance changes; 200 degrees at 10,000 hours of continuous use; at 350 degrees can also use the period of time. Requirements of the occasion are widely used in heat: heat-resistant handle thermos bottle seal pressure cooker ring cold: ordinary rubber late as -20 degrees to -30 degrees, that is silicone rubber in the -60 degrees to -70 degrees, still has good flexibility, some specially formulated silicone rubber can withstand very low temperatures. Low-temperature sealing weather resistance: ordinary rubber in the role of corona discharge ozone rapidly degraded, while the silicone rubber is not subject to ozone effects. And for a long time in the UV and other weather conditions, the properties are only small changes. Outdoor electrical properties of the sealing material: silicone rubber with high resistivity and temperature in a wide frequency range and its resistance remained stable. While silicone rubber for high-voltage corona discharge and arc discharge with a good resistance. TV high-voltage electrical apparatus high-voltage insulators other conductive parts: When adding conductive fillers (such as carbon black), the conductive silicon rubber contact points will have a keyboard, thermal conductivity: thermal conductivity when adding some filler, the silicone rubber has a thermal conductivity chip thermal gasket copiers, fax machines thermal roll radiation resistance: silicon rubber containing phenyl greatly increased radiation-resistant nuclear power plants with electrical insulation cable connectors Flammability: combustible silicone rubber itself, but add a small amount of flame-resistant agents It will have a flame-retardant and self-extinguishing; and due to the organic halide-free silicone rubber, which when burned does not emit smoke or toxic gases. Various fire situations strict permeability: Silicone rubber and plastic film to play than the regular wax film has better breathability. The other feature is the permeability of different highly selective. Medical supplies gas exchange membrane artificial organs 2. The main properties of silicone rubber and application: its curing temperature of silicone rubber, can be divided into high-temperature (heat) curing type and type and room temperature curing two categories, high-temperature plastic primarily used in the manufacture of silicone rubber products, and plastic at room temperature is mainly as adhesives, potting materials or mold. (1) heat vulcanized silicone rubber (HTV) hot-vulcanized silicone rubber (HTV) silicone products is the most important class, methyl vinyl silicone rubber (VMQ) is the most important varieties of HTV, commonly known as high-temperature plastic. Methyl vinyl silicone rubber (gum) is a colorless, odorless, non-toxic, no mechanical impurities jelly, raw rubber by the need to add the appropriate reinforcing agents, structural control agents, curing agent mixed with additives refining, and then heated compression molding or extrusion, and then by a variety of products made of vulcanized Sec. The products have excellent electrical insulation, arc resistance, corona, spark strong, waterproof, moisture-proof, impact resistance, resistance to shock, with physical inertia, air permeability and other properties. Mainly used in aviation, instrumentation, electronics, marine, metallurgy, machinery, automotive, medical and health departments to do a variety of shapes of seals, gaskets, pipes, cables, also do the human body organs, blood vessels, breathable membrane and rubber molds, precision casting release agents. (2) RTV silicone rubber (RTV) RTV silicone rubber molding and processing generally include condensed into two categories. Plastic molding temperature increase is linear with a vinyl polysiloxane-based gel to hydrogen siloxane as crosslinker, in the presence of a catalyst at room temperature to the temperature cross-linking reaction to become elastic. It has good heat resistance, water repellency, electrical insulation, and because the active end of the introduction, it has excellent mechanical properties, especially in the tensile strength, relative elongation and tear strength markedly on improved. It is suitable for a variety of curing methods, such as radiation vulcanization, peroxide vulcanization molding curing and processing, are widely used in heat, moisture, electrical insulation, high strength silicone rubber products and so on. Condensation-type RTV silicone rubber is silanols and other active substances for the condensation reaction between the characteristics at room temperature can become cross-linked silicone rubber elastomer, the product is divided into two kinds of one-component packaging and two-component packaging form. One-component RTV silicone rubber (RTV-1 short plastic) is condensed liquid silicone rubber is one of the main products. Usually based polymers, crosslinking agents, catalysts, fillers and additives formulated. Products packed in a sealed tube, the use out of, their own after contact with air into the elastomer curing, extremely easy to use. Vulcanized rubber in (-60 ~ +200 ℃) temperature range long-term use, with excellent electrical insulation properties and chemical stability, the ability of water resistance, ozone resistance, weather aging, a variety of metals and non-metallic materials with good adhesive take of. Mainly used for a variety of electronic components and electrical equipment, coating, encapsulation material from the insulation, moisture, shock effect; as semiconductor devices, surface protection material; also be used as elastic sealing materials and adhesives interstitial. Two-component room temperature vulcanized silicone rubber (RTV-2 rubber referred to) the use of RTV-1 is not easy to glue, but the proportion varied components, a variety of performance specifications can be a variety of curing products, but also the depth of curing, which is widely used in electronic appliances, automobiles, machinery, construction, textile, chemical, light industry, printing industry for insulation, packaging, caulking, sealing, moisture and shock and production of the roller material. In addition, RTV-2 has excellent mold release, and thus as a soft-mode materials is used extensively for artifacts, crafts, toys, electronics, mechanical parts such as replication and manufacturing. Silicone sealant is one of the typical applications of glass curtain wall. The glass and aluminum frame structure with a silicone adhesive material received as a wall, expansion joints are made with silicone rubber weather sealing. Other applications include for aluminum doors and windows and sealing around windows and doors, glass installation and mobile slot seam, rivets and screws sealed: kitchen, bathroom, sanitary ware and bathroom countertops, walls, furniture between the waterproof seal; aquarium, ceiling, metal roof, windows, counters, wall panels, color plate seals; for highway section between the waterproof caulking and sealing. RTV sealant in addition to construction, also includes for the aerospace, nuclear power, electronics, machinery, automobile industry, sealing materials, potting of electronic components used in silicone potting material, as soft silicone mold material mold plastic. Relatively small demand for these species, but in many cases is essential.
3. Development of China's rubber industry since 1943, the U.S. Dow Corning (DC) company was the first industrial production of organic chlorosilane since, after 50 years of development, in today's international market, the formation of silicone DC, GE, RP, Wacker, Shin-Etsu's five strong situation. The world's major silicone dozen professional companies, methylchlorosilane increasing scale of production, and secondary processed products of silicone oil, silicone rubber, silicone resin, silane coupling agent, silane surfactants is widely used in various industrial sectors, silicone-based products as many as 5,000 kinds of specifications, production and sales increasing. The past 30 years, silicone industrial products maintained a growth rate of 8% to 15%, far more than the general national economic growth. At present the application of organic silicon in China has been very extensive, the number and variety continue to grow, applications continue to broaden, China has become the most potential of silicone products market. (1): Heat vulcanized silicone rubber as the industrial structure of different countries and regions, high-level structure of silicone are not the same, such as the United States, silicone rubber silicone market share of 25 to 30%, about 40% in Europe and Japan more than 50 %, of which nearly half of the heat curing silicone rubber, silicone rubber in China accounted for a greater proportion, about 60%. In China, the heat curing silicone rubber is mainly used for electrical and electronic industry, office automation equipment and automotive industry, with the development of national economy, the demand for heat curing silicone rubber is not less than 20% of the annual growth rate. Heat vulcanized silicone rubber production technology complex, high value-added products in the world of organic silicon market, its share of sales accounted for about 10%, sales are up 30 to 40%. The use of heat curing silicone rubber extrusion products can be broadly divided into 35%, 30% of molded products, wire and cable with 30%, 5% coating materials, consumption growth of 4 to 6%. In developed countries, heat curing silicone rubber raw rubber and rubber production scale and production technology has reached a high level, the United States back in the early 1960s, Dow Corning Corporation have a continuous polymerization-kiloton device. In our earliest research and HTV silicone rubber and production units are Chenguang Chemical Research Institute and Research Institute of Jilin Chemical Company, the first production plant was built in 1960, the production scale of 5t / a. To now, China has built more than 40 of raw rubber production equipment sets, with a total production capacity of nearly 80,000 tons. However, domestic manufacturers of silicone rubber widespread low productivity, inadequate technical support, production of high-grade rubber and less problems. According to incomplete statistics, China's 2003 heat curing silicone rubber raw rubber production to 4 million tons, while the actual year of China's rubber consumption of nearly 10 million tons of high quality rubber most dependent on imports. At present, China silicone rubber consumption in excess of 10% of world consumption, the fastest growing application area is the production of silicone rubber conductive keys (key pads). Plants concentrated in Shenzhen, Xiamen, Nantong and other regions, key glue has become hot vulcanized silicone rubber largest user; silicone rubber insulators and surge arresters in place of porcelain, glass, steel insulators, surge arresters of the third generation of products in harsh climatic environments , now has foreign transmission system for its large, China's coastal areas have begun to use, the market prospect is very broad; with silicone rubber sealant for automobiles produced in China with a capacity of several tons, of which heat vulcanized silicone about 3,000 tons of rubber, and with the improvement of automotive-grade silicon rubber consumption will be significantly increased; In addition, the silicone rubber in the power cable, nuclear power plants, ships and other control cables, electronic equipment internal wiring, motors, TV, etc. Lead-out aspects of a good prospect. In the civil context, with hot vulcanized silicone rubber nipple of nursing bottle, thermos bottle stopper, a pressure cooker gaskets and hoses and other food vending machines have been widely used, some of the raw rubber and rubber have been exported to foreign countries, such as dawn Chemical Research hospital pacifier with rubber export to Iran for several years, indicates that China silicone rubber products have entered the international market. In modern medicine, silicone rubber has been very extensive and important uses, such as noise abatement measures for the manufacture of silicone rubber ear plugs, rubber suction fetal head, artificial blood vessels, tympanic membrane repair piece, artificial airway, artificial lungs, artificial bone, silicon Rubber duodenal tubes, etc., effects are very good. (2) RTV silicone rubber (RTV) as the status of the main RTV adhesive sealants, potting materials and mold. Largest amount of total species are used in the construction and decoration market sealant products (commonly known as "glass glue"), mainly for high-rise buildings such as glass curtain wall and other new construction in the form of adhesive sealing requirements. In developed countries, the amount of silicone sealant to keep the most recent years, more than 10% annual growth rate. According to statistics, China's 2000 consumption of silicone sealant up to 5 million metric tons, and is an annual rate of 20% - 30% growth rate. Silicone Building Sealant which most of the domestic market by foreign companies of Dow Corning, GE and other companies take. In recent years, with the technological level and the expansion of market demand, the rapid development of silicone sealant production, many companies invest and build factories or expand the scale, has formed Zhejiang, Guangdong and two silicone sealant production base. As the organic silicon industry, technological progress, the quality of domestic silicone rubber has been greatly improved, along with the price of domestic structural adhesive is much lower than the Jin Koujiao make homemade glue in the cost performance on an absolute advantage. On the other hand, the domestic manufacturers, timely delivery, and can provide users with fast, attentive service, domestic brands over the years with good effect, winning more and more users, the market share of structural adhesive made from a few years ago 10% to 50% or more.
4. Problems and develop recommendations (1) heat curing silicone rubber silicone rubber developed world production and consumption have reached a very high level, and develop very rapidly. Although China in recent years in HTV's production technology and production capacity has been greatly improved, and there have been some silicone rubber production technology and products into the international market. But overall speaking, China's rubber industry with the international advanced level, there is still a large gap. Therefore, the development and establishment of larger economies of scale with the heat curing silicone rubber raw rubber and rubber plant, rubber series of varieties, especially the development of high-quality varieties, for change in China's rubber output and rely on a variety of foreign status and the promotion of organic silicon and related industries and technological progress has a great significance. (2) RTV silicone rubber to one-component sealant, for example, due to disorderly competition in the market, most manufacturers to reduce costs, lower prices of recycled material used as the main raw material, also used by cross-linking Most of the products for a number of small factories, the quality of instability, resulting in decline in the overall quality of the final product, performance is affected. High-performance sealant is mainly used imports and packing products, such as curtain wall with the structural adhesive and weather such as plastic. These are the future should pay attention to solve the problem. High-performance buildings and processing silicone rubber sealant is to develop hot spots. Building Sealant focus is to improve the dry time and curing time, and the adhesion with the substrate, especially with the pouring of concrete adhesion. And should achieve continuous production, to overcome the intermittent presence of the production process with plastic is less stable, loss of large effect are not disadvantages. Silicone rubber was mainly to improve its flexibility and transparency, there is the development of single-component silicone rubber. For other special uses of silicone rubber, silicone rubber potting compound, such as flame retardant, high damping silicone rubber, high corrosion resistance of high tear resistant silicone rubber, silicone rubber anti-electromagnetic interference, high temperature (350 ℃ above) such as silicone rubber, although aggregate demand is not great, but on China's national defense construction and economic development of cutting-edge technology and have an irreplaceable role, which also requires us to make great efforts to research and development.
Editor's note: The Magic of silicone rubber is changing our lives, but we also see that with the international advanced level, my level of silicon rubber in terms of scientific research or practical application of technologies from the existence of a gap, the need in silicone rubber research and production people work together to continuously develop more and better silicon rubber products to meet the needs of the people.