Silicone mat, silicone products, silicone rubber seals and other issues?
Introduction of silicone rubber products - Silicone Rubber
Silicone Rubber is a high molecular weight (molecular weight is normally 40 to 80 million) of polysiloxane (ie, raw rubber) by adding a variety of reinforcing fillers and other additives, organic peroxides used as curing agent, by pressure molding (molding, extrusion, rolling) or injection molding, and high temperature cross-linking into the rubber. This rubber generally referred to as silicone rubber.
High-temperature vulcanized silicone rubber vulcanized in two stages, the first phase is silicone rubber, reinforcing agents, additives, curing agents and structural control agents for mixing, then mixing materials increases in the metal mold Heat forming and curing pressure, the pressure of 50 kg / cm2 or so, the temperature is 120 ~ 130 ℃, for 10 to 30 minutes, the second phase is removed from the mold silicone rubber, into the oven at 200 bake at 250 ℃ for several hours to 24 hours. To further vulcanized rubber, while volatile decomposition of organic peroxides.
Silicone rubber reinforcing filler is silica of various types, which can increase ten times the strength of vulcanized rubber. Various additives so as to minimize the cost of rubber, plastic materials to improve performance and give a variety of special properties of vulcanized rubber, such as flame retardant, conductive, etc.. Crosslinking agent is organic peroxides, such as benzoyl peroxide, 2,4 - dichloro benzoyl peroxide, 2 dry base peroxide, 2,5 - t-butyl peroxy hexane . structural control agent is expected to avoid placing too long rubber compound to produce the "structural" to harden plastic material hardens, it is difficult to join the aging process, and can be used methyl-hydroxy-2-hydroxy-phenyl silicone oil, or 2 wins alkanes as the structural control agent.
Silicone rubber main chain side groups can be methyl, ethyl, vinyl, phenyl, trifluoropropyl, etc.. The most common is methyl, can bring in other groups to improve the processing performance and other properties. Thus, according to the side Kiki groups and different rubber formulations, can be a variety of different uses of silicone rubber, are generally divided into the following several types: Tong Yong-type (Han-methyl and vinyl), high temperature and Diwen type (including phenyl, methyl and vinyl), low compression (including methyl and vinyl), low shrinkage (to volatile) and solvent (fluorine rubber), etc.. Here are several important types of silicone rubber.
1. Methyl silicone rubber
Dimethyl silicone rubber is first put into commercial production of a silicone rubber, can be -60 ~ 200 ℃ range to maintain good flexibility, good aging resistance, has excellent electrical insulation properties and moisture, shock and physical inertia, etc. characteristics.
Dimethyl silicone rubber coating is mainly used for strong material, it can be made of extruded and rolled products for the electronics, aerospace, automotive and medical industries. However, dimethyl silicone rubber vulcanized low activity for the manufacture of thick products, the curing difficulties, inner foaming temperature compression and large, it has now been replaced by methyl vinyl silicone rubber.
2. Methyl vinyl silicone rubber
Since the introduction of silicone rubber macromolecular structure of a small amount of vinyl can significantly improve the performance of silicone rubber vulcanization process, so in the current application of the silicone rubber, most with vinyl. Methyl vinyl silicone rubber is the most common of a silicone rubber, silicone rubber at home and abroad now dominate production. As part of its introduction of unsaturated side chain of vinyl, it's processing performance and mechanical properties are better than two base silicone rubber. In addition it has two general characteristics of silicone rubber, it also has a wide temperature range, can be in a range of 60 ~ 260 ℃ to maintain good flexibility, it is easier than the dimethyl silicone rubber vulcanization, has less compression deformation, good solvent resistance and resistance to the expansion of the stability of high-pressure steam and excellent cold resistance, etc., but also because the lower activity of peroxide used for curing, thereby reducing the vulcanization of rubber stability of bubbles and poor weaknesses. So it is generally available with methyl vinyl silicone rubber products making thicker. Methyl vinyl silicone rubber silicone rubber is the most widely used species in recent years, emerging high performance and special-purpose silicon rubber, mostly based on vinyl silicone rubber-based adhesive, such as high strength silicone rubber, low- compression silicon rubber, without post-curing silicone rubber, heat conductive silicone rubber and silicone rubber, etc.. Methyl vinyl silicone rubber in the aviation industry, widely used as gaskets, sealing materials and fragile layer of shock protection components; in the electrical industry can be used for electronic components and other high insulation materials, high temperature potential of the dynamic seals, long-distance communications equipment, underground ring; in medicine, due to methyl vinyl silicone rubber on the human body's physiological response to a small, non-toxic, it is used for orthopedic surgery, artificial heart valves, blood vessels.
3. Methyl phenyl vinyl silicone rubber
Phenyl vinyl methyl silicone rubber in methyl vinyl silicone rubber into the molecular chain segment methylphenyl silica or silica-diphenyl-derived segment products. The polysiloxane side groups on the introduction of the phenyl, as undermining the structure of dimethyl siloxane regularity, greatly reduced the crystallization temperature of the polymer, expanding the scope of application of polymer materials at low temperature. Therefore, methyl phenyl vinyl silicone rubber addition to methyl vinyl silicone rubber compression of all the small, wide temperature range, anti-oxidation, weathering, vibration, moisture, and good electrical insulation properties, but also excellent low temperature resistance, erosion resistance and radiation properties.. These properties with molecular chain phenyl content vary, in general, phenyl content (the ratio of phenyl and silicon atoms) in the 5 to 10% of said low-phenyl silicone rubber, it has a unique cold performance, -70 ~ -100 ℃ can maintain the flexibility of rubber, all rubber in a low-temperature properties of the best, plus it combines the advantages of methyl vinyl silicone rubber and the cost is not high, so much to replace a vinyl silicone rubber trend. Phenyl content of 20 ~ 40%, said that the benzyl methyl vinyl silicone rubber silicone rubber both the advantages and cost is not high, so much the trend to replace methyl vinyl silicone rubber. Phenyl content of 20 ~ 40%, said the phenyl silicone rubber, which has excellent flame retardant properties, once the fire to extinguish. Phenyl content of 40 ~ 50%, said high-phenyl silicone rubber, which has excellent radiation resistance, resistance to γ-rays as 1xI08 Roentgen. In general, as the phenyl content increases, the rigidity of the molecular chain silicone rubber increases, temperature-resistant properties of silicone rubber decreased gradually, but with the phenyl content increases, improved vulcanizate flame and radiation resistant according to sex. Content from the rubber plantation
Phenyl vinyl methyl silicone rubber is the aerospace industry, advanced technology and other sectors of the national economy one of the important materials available for making a variety of molded and extruded products for the aviation industry's cold-resistant rubber and used for ablation, heat aging or radiation-resistant parts of the ring, pad, such as tubes and rods.
4. Fluorosilicone rubber
Fluorosilicone rubber is γ-trifluoropropyl methyl polysiloxane. Fluorosilicone rubber has excellent resistance to chemicals, solvents and oil-resistant properties, such silicone rubber in the non-polar solvents in the swelling of small, cold resistance and thermal stability, resistance to fire of Ye Hao, so the plane , rockets, missiles, space flight, petrochemical fuel and lubricants used as contacts with the hose, gaskets, seals, fuel tanks and so the village can also be used to make corrosion-resistant clothing, gloves and coatings, adhesives, etc. .
5. Silicone rubber nitrile
As the polymer side chain containing β-nitrile, ethyl or propyl γ-polar nitrile groups, greatly increasing the interaction between the molecular chains, improved oil and solvent resistance. Meanwhile, the introduction of a certain amount of alkyl nitrile, destroyed the regularity of polymer structure, but also greatly improved cold tolerance. The type of alkyl nitrile and its content, a great impact on performance, such as containing 7.5 mol% γ-propyl nitrile rubber, low temperature performance and low-phenyl silicone rubber similar to (the glass transition temperature of -114.5 ℃), phenyl silicone oil resistance than good. With the increased content of γ-propyl nitrile to 33 to 50 mole% cold reduction, improved oil resistance. Instead of using β-γ-nitrile nitrile ethyl propyl nitrile rubber can improve the heat resistance, can withstand 250 ℃ hot air aging.
The main advantage of nitrile rubber is oil resistant and high performance bath agent can range -60 ~ 180 ℃ to maintain flexibility, therefore, can be made of oil resistant rubber products for the aviation industry, automobile and oil industries; also environment as a high-performance aircraft fuel tank sealant sealing agent, in -54 ℃ to 200 ℃ or more to remain sealed. Nitrile rubber processing equipment can be common.
6. Phenylene silicone rubber
Phenylene main characteristics of silicone rubber with excellent resistance to radiation, the radiation resistance for the common methyl vinyl silicone rubber of 10 to 15 times as high phenyl silicone rubber of 5 to 10 times, therefore, can be used aerospace industry, nuclear industry and nuclear reactor as a high-energy radiation-resistant cables, sheathing, gaskets, and heat shrinkable tubes.
7. Ethyl silicone rubber
The introduction of the ethyl side chain on the obtained diethyl silicone rubber, its outstanding performance is especially good cold, cold better than the dimethyl silicone rubber and methyl vinyl silicone rubber in general. The higher content of ethyl, cold as possible. However, the reactivity ratio of methyl ethyl large, therefore, with the ethyl content is, the heat resistance decreased. Used as a low-temperature ethyl silicone rubber, to the polymer containing silicon-oxygen segment diethyl 8 mol% is appropriate. Ethyl silicone rubber temperature is generally -70 - 200 ℃. Content from the rubber plantation
8. Silicone rubber N
The main advantage of silicone rubber, nitrogen is a superior thermal stability, in the 430 ~ 480 ℃ does not decompose, and some even over 500 ℃ high temperature capability. Nitrogen silicon rubber prominent weakness poor hydrolytic stability, once was not considered promising. Later discovered that the introduction of the main chain ring disilazane the polymer has good thermal stability. Support modification of silicon containing aromatic ring disilazane elastomer, in the air is not heated to 425 ℃ weight loss, 570 ℃ when the weight loss of only 10%, and has good hydrolytic stability. Rubber Information Network, xiangjiaoyuan.com silicone rubber products introduction of 2 - silicone rubber
RTV silicone rubber (RTV) is the advent of the sixties a new silicone elastomer, this rubber is the most notable feature at room temperature without heating, pressure can be cured in situ, very easy to use. As a result, the advent of silicone products on to become an important component. RTV silicone rubber is widely used as adhesives, sealants, protective coatings, potting and molding materials, in all walks of life has its purpose. RTV silicone rubber as low molecular weight, it is known as liquid silicone rubber is known, its physical form is usually the flow of fluid can be cream or thick, its viscosity centistokes at between 100 ~ 1000000. According to the use of the request, the pre-vulcanized rubber material dubbed material automatic leveling of the perfusion flow but can be painted or not scrape the putty. RTV silicone rubber filler used in a similar high temperature vulcanized silicone rubber, reinforced with silica to make vulcanized rubber with 10 to 60 kg / cm 2 tensile strength. Fill can add different compound additives have different specific gravity, hardness, strength, mobility and thixotropy, and to make vulcanized rubber with flame retardant, conductive, thermal conductivity, resistance to erosion and other special features.
RTV silicone rubber its packaging can be divided into single-component and two-component RTV silicone rubber, curing mechanism can be divided according to type and processing condensation forming. Therefore, by component RTV silicone rubber, curing mechanism and the use of technology can be divided into three types, namely, one-part RTV silicone rubber, two-component condensation-type RTV silicone rubber and two-component addition cure silicone rubber .
Single component and two-component condensation-type RTV silicone rubber raw rubber are α, ω-dihydroxy polysiloxane; add molding silicone rubber is alkenyl and hydrogen containing side groups (or terminal group) of polysiloxane, because aging often the case in slightly higher than room temperature (50 ~ 150 ℃) can achieve a good curing effect, therefore, also known as low-temperature vulcanized silicone rubber (LTV).
Three series of room temperature vulcanized silicone rubber has advantages and disadvantages: one-component RTV silicone rubber has the advantage of easy to use, but more difficult in deep curing speed; two-component room temperature vulcanized silicone rubber has the advantage of tightly heat curing shrinkage rate is very small, not expansion, no internal stress, curing can be internal and surface at the same time, you can deep sulfide; add molding silicone rubber vulcanization time depends mainly on temperature, therefore, the temperature of the regulator can control the curing speed.
1. One-component RTV silicone rubber
One-component RTV silicone rubber vulcanization reaction is to rely on water from the air caused. Commonly used cross-linking agent is methyl 3-acetoxy-silane, and its Si-OC bond is easily hydrolyzed acetoxy hydrogen bonding with water into acetic acid, which will go to the original hydroxyl water acetyl oxygen position, a 3-hydroxy-methyl silane. 3-hydroxy-methyl silane very unstable, with the hydroxyl end groups for the condensation of a linear silicone cross-linking structure. Normally, alcohol-terminated silicon-containing organic silicone rubber and fillers, catalysts, crosslinking agents, and sealed the hose with the dose, the use of time out of the container, by means of air into the water and the sulfide elastomers, and release low molecular weight materials. Crosslinking agent addition of methyl 3-acetoxy-silane, but also can contain alkoxy, oxime, amine, amide, keto silane. When cross-linking with the alkoxy alcohol after release, as dealcoholized one-component RTV silicone rubber, when and oxime oxime generated after crosslinking, as deoximation type RTV silicone rubber, therefore, with the cross-linking different agents, one component RTV silicone rubber for deacidification type deoximation type dealcoholized, de amine, off and off Keto Amide-type and many other varieties, but the acid removal type is the most widely used a kind.
One-component RTV silicone rubber vulcanization time depends on the curing system, temperature, humidity and the thickness of silicone rubber to improve the environment temperature and humidity, can make the vulcanization speed up the process. In a typical environmental conditions, generally 15 to 30 minutes, the silicone rubber surface can not sticky, the layer thickness of 0.3 cm can be cured in one day. Curing depth and intensity in three weeks or so will be gradually increased.
One-component RTV silicone rubber has excellent electrical properties and chemical inertia, and heat resistance, natural aging, flame resistance, moisture, ventilation and other properties. Their range of -60 ~ 200 ℃ to maintain long-term flexibility. It is cured without heat-absorbing, tightly heat, curing shrinkage is small, good adhesion of the material. So, mainly for adhesives and sealants, Other applications include in situ forming gaskets, protective coatings and caulking materials. Many one-component silicone rubber adhesive formulations to demonstrate a variety of materials such as most metals, glass, ceramics and concrete with automatic adhesive properties, such as bare aluminum, the shear strength of up to 200 lb /? 2, tear strength up to 20 pounds?? /? 2 (0.35 joules / cm 2). When the bonding difficulties, can be carried out on the substrate primer to improve bonding strength, primer can be with the reactive silane monomer or resin substrate when they are cured, generate a suitable modification Silicone adhesive on the surface.
One-component RTV silicone rubber although easy to use, but it is by curing lazy moisture in the atmosphere, so that the thickness of vulcanized rubber is restricted only for the needs of the thickness of 6 mm the following occasions.
One-component RTV silicone rubber vulcanization The depth of reaction is carried out gradually from the surface, the thicker layer, the slower curing. When the deep need fast curing, curing method can be used stratified water gradually, each time adding some plastic materials, such as curing after feeding, thus reducing the total curing time. MgO can accelerate the deep rubber vulcanization.
Two-component room temperature vulcanized silicone rubber two-component room temperature vulcanized silicone rubber molding and processing can be divided into condensation type.
2. Two-component condensation-type RTV silicone rubber
Two-component condensation-type RTV silicone rubber is the most common type of room temperature vulcanized silicone rubber, the raw rubber is usually hydroxy-terminated polysiloxane, and then the other with the agent, the composition of the catalyst combination of rubber, this rubber viscosity range from 100 centistokes to 1 million centistokes between. Two-component RTV silicone rubber vulcanization reaction does not depend on the moisture in the air, but to be triggered by the catalyst. Is usually silicone rubber, filler, crosslinking agent, as a component packaging component packaging as another catalyst alone, or with other combinations, but must be the catalyst and the crosslinking agent packaged separately. No matter what packaging, only when the two components together until completely mixed beginning to solidify. Commonly used cross-linking agent is ethyl silicate, the catalyst is dibutyltin dilaurate. According to the nature of the final product required to add appropriate fillers and additives. In recent years, many countries as dibutyltin dilaurate are moderately toxic levels of substances in the food bag and blood bag ban by adding dibutyltin has been largely replaced by low toxicity, octyl tin.
Two-component condensation-type RTV silicone rubber vulcanization time depends on the type of catalyst, amount and temperature. The more the faster curing catalyst, the shorter the time while on hold. At room temperature, the time usually set aside a few hours, to set aside time to extend the plastic materials, available cooling methods. Two-component condensation-type RTV silicone rubber rafters in order to achieve full cure at room temperature a day or so, but the temperature at 150 ℃ only 1 hour. Through the use of accelerator γ-aminopropyl triethoxysilane were synergistic effect can significantly improve the cure rate. Two-component RTV silicone rubber available in a 65 ~ 250 ℃ temperature range remains flexible and has excellent electrical properties and chemical stability, the ability of water, ozone resistance, resistance to weathering, coupled with use of simple, powerful process applicability therefore, widely used as a potting and molding materials. A variety of electronic, electrical components coated with silicone rubber, potting, you can play a moisture (corrosion, shock and other protection. Can improve the performance and stability parameters. Two-component room temperature vulcanized silicone rubber is particularly suitable for filling in so deep sealing material and has a faster curing time, and this is better than the one-component RTV silicone rubber between.
Two-component RTV silicone rubber has excellent anti-sticking after the performance, with minimal shrinkage during curing, therefore, suitable for the manufacture of soft tooling for the casting resin, polyester resin, polystyrene, Polyurethane, vinyl, wax, low melting point alloy mold. In addition, the use of two-component RTV silicone rubber with high simulation performance can copy a variety of exquisite patterns. For example, available on the Heritage copy to copy the ancient bronzes, in leather production can be used to copy the snakes, pythons, crocodiles and pangolins and other animals, striae, serve as real effect.
Two-component room temperature vulcanized silicone rubber should pay attention to the use of several specific questions: First, the base material, crosslinking agent and catalyst were weighed and then mixed in proportion. Usually the two components should be available in different colors to use, it can be directly observed from the mixing of two components, mixing process should be done carefully in order to minimize the amount of gas attached. After the rubber mix (color uniform), can be standing or decompression (700 mm Hg vacuum) to remove air bubbles, all bubbles to be discharged, the provisions at room temperature or in temperature for a period of time that is vulcanized into the silicon rubber.
Two-component room temperature vulcanized silicone rubber siloxane main chain side groups than methyl, the can with other groups such as phenyl, trifluoropropyl, cyanoethyl, etc. replaced to improve their resistance to cold, heat resistance to radiation or solvent properties. Meanwhile, heat can be added as needed, flame retardant, thermal conductivity, conductive additives to the system was resistant to erosion, fire, thermal and electrical conductivity properties of silicone rubber.
1. Methyl silicone rubber
Methyl silicone rubber silicone rubber for the common old varieties with water, ozone resistance, arc resistance, corona resistance and resistance to weather and aging. It can be a 60 ~ 200 ℃ temperature range. Therefore, the widely used electronic and electrical components of the injection, and sealing materials, instrumentation, moisture, shock resistance, high temperature injection, and sealing materials. Can also be used to make molds for casting polyester resin, epoxy resin and the low melting point alloy parts. Also be used as dental impression material. Methyl silicone rubber coating in the cotton, paper bag, it can be made of conveyor belt for conveying sticky materials and bags.
2. Double-phenyl-methyl silicone rubber
Phenyl methyl silicone rubber double addition of methyl silicone rubber with good performance, compared with methyl silicone rubber with a wider temperature range (-100 ~ 250 ℃). Phenyl content of 2.5 to 5% of the low-phenyl silicone rubber (108-1) in -120 ℃ low temperature flexibility, is the low temperature performance of silicone rubber in one of the best varieties; phenyl content of 10 ~ 20% of the room temperature plastic (108-2) has good resistance to irradiation, ablative and self-extinguishing nature, if adding a certain amount of heat which additives such as Fe2O3, and so can improve the thermal aging resistance, suitable for 250 ℃ and high temperature ablation-resistant putty to use or make coatings and encapsulation materials.
Methylphenyl room temperature glue and other adhesive at room temperature, as do impregnation, impression and the mold release used. To increase the adhesion with other materials must use the material before the material being adhesive surface treatment, surface treatment of the following steps: using acetone solvent on the surface of cleaning 1 or 2 times, and then deal with a surfactant ~ 2 times within a drying oven at 60 ℃ for a few minutes, then a layer of material little sticky surface membrane, can be the glue.
3. Methyl silicone rubber block
Methyl-block-methyl silicone rubber is RTV silicone rubber modified varieties, it is by the hydroxyl head of polydimethylsiloxane (107 gel) and methyl silane oligomer ( molecular weight of 3 to 5) of the copolymer. In dibutyl tin dilaurate as catalyst, polydimethylsiloxane in the hydroxy and poly methyl triethoxysilane ethoxy condensation in three-generation structure of the polymer, after the bomb by the vulcanization to the body than methyl silicone rubber with high mechanical strength and adhesion, can be a 70 ~ 200 ℃ temperature range of long-term use.
Methyl silicone rubber block shock, moisture, waterproof, breathable, ozone resistance, resistance to weathering, resistance to weak acid weak base properties. It is a very good electrical insulation properties, but also has good adhesion and low cost. Therefore, can be used in potting, coating, die, mold release, the release of drug delivery and other occasions. Plastic encapsulation at room temperature with methyl-block electronic components are shock, moisture, sealing, insulation, stability, the role of various parameters. The methyl-block room temperature plastic coating directly to the speaker, the speaker can reduce and eliminate points of IF, after the speaker resonance frequency performance after vulcanization can be reduced about 20 Hz. Gel at room temperature in methyl-block with a certain amount of additive into the paper can be used as anti-adhesives. In the food industry, candy, cookies belt on a thin layer of methyl-block room temperature plastic, it can improve the anti-sticking properties camp to improve the appearance of food, improve the utilization of raw materials.
Gel at room temperature in methyl-block adding an appropriate amount of fumed silica, can be used to install windows, curtain walls, window frames, prefabricated panel joints, expansion joints airport runway. In addition, computer memory can be done in the core and adhesive templates can also be made conductive and non-conductive silicone rubber silicone rubber adhesives. Block with a methyl silicone rubber handle fabrics can improve the fabric handle, soft, and wear resistance of song.
4. Room temperature vulcanized silicone rubber eye
Nitrile at room temperature vulcanized silicone rubber is poly-β-nitrile methyl siloxane, silicone rubber RTV guess except with silicone rubber lightfastness, resistance to ozone, resistant to moisture, resistance to high and low moderate high electrical insulation properties, the main features of the non-resistant polar solvents, such as resistance to aliphatic, aromatic solvents, good performance, its oil resistance and oil-resistant nitrile rubber with close to normal can be used as components of oil pollution and oil sealing of electronic components filling material injection.
5. Silicone rubber room temperature vulcanizing fluorine
RTV fluorosilicone rubber is poly γ-trifluoropropyl methyl siloxane, its main characteristic is resistant to fuel oil, solvent and high temperature resistance to degradation, also has good extrusion properties. Mainly used in supersonic aircraft integral fuel tank sealing, caulking, fluorine silicon rubber gasket, gasket bonded fixed; silicone rubber and fluoro silicone rubber adhesive, and chemical engineering and general industrial fuel oil resistance; solvent parts bond.
6. Room temperature vulcanized silicone rubber phenylene
Room temperature vulcanized silicone rubber in which silicon-phenylene benzene (biphenyl) support siloxane polymer, and its advantage is excellent performance of resistance to high-energy rays. Test proved that γ-ray Roentgen withstand 1x109 or 1xl018 neutron / cm 2 after neutron irradiation, can still maintain elasticity, compared with room temperature vulcanized silicone rubber is 10 to 15 times higher than room temperature vulcanized silicone rubber-phenyl-5 ~ 10 times.
Room temperature vulcanized silicone rubber phenylene applicable atomic energy industry, nuclear power plants and space flight so as temperature, radiation-resistant adhesive sealing materials and electrical insulation protection layer.
3. Add molding silicone rubber
Two components additional flexible silicone rubber silicone rubber silicone gel and divided, the former lower strength, which strength is higher. Their curing mechanism is based on the organic end groups on the silicone rubber vinyl (or allyl) and the crosslinking agent molecules on the addition reaction of silicon-hydrogen hydroxyl (hydrogen silicide reaction) to complete.
In the reaction, with hydride functional polysiloxane used as crosslinking agent (curing agent) chloroplatinic acid or other soluble platinum compound as catalyst. Curing reaction was carried out at room temperature. Do not release by-products. Because cross-linking process does not release low molecular weight material, so add molding silicone rubber in the curing process does not produce contraction. This type of vulcanized rubber non-toxic, high mechanical strength, excellent resistance to hydrolytic stability (even under the high pressure steam), good low compression set, low flammability, may be the depth of curing, and curing speed can be used to control the temperature advantages, it is to develop a class of domestic silicone rubber.
Addition of RTV silicone rubber packaging is generally sub-M, N for packaging two components: the catalyst and capable of containing vinyl groups as a component of organic silicon polymer; hydrogen polysiloxane cross chain agent for another component.
Increase in molding high-strength silicone rubber as low linear shrinkage, curing time is not release low molecular weight, and therefore an excellent material for molding. In the machinery industry has been widely used to mold to cast epoxy resin, polyester resin, polyurethane, polystyrene, vinyl plastic, wax, low melting point alloy, coagulation upper. The use of addition stifled the high temperature vulcanized silicone rubber simulation, non corrosive, molding process is simple and easy mold release characteristics, suitable for copying and arts and crafts heritage replication.
Silicone rubber products introduced ter - silicone gel
Add molding silicone rubber is a colorless or slightly yellow transparent oily liquid, after curing a soft transparent silicone gel. This gel can be -65 ~ 200 ℃ temperature range of long-term flexibility, it has excellent electrical properties and chemical stability, water resistance, ozone resistance, resistance to weathering, water-repellent, moisture, shock, no corrosion, and has physiological inert, non-toxic, odorless, easy-to-perfusion, to deep curing, linear shrinkage rate, simple operation, silicone gel is widely used in the electronics industry electronic components moisture, smuggling, coating and insulation potting materials, electronic components and assemblies from dust, moisture, shock, and insulation protection. If a transparent gel encapsulation of electronic components, not only can play the role of shock waterproof protection, you can also see the components and can be detected with probe component failure, replacement, damage to the silica gel can be re-potting repair.
Because silicone gel high purity, easy to use, has a certain flexibility, it is an ideal transistors and integrated circuits within the coating material, can improve the passing rate of semiconductor devices and reliability; silicone gel can also be flexibility of optical instruments used for adhesive.
In the medical silicone gel can be used as planting the body's organs such as artificial breasts, as well as to repair damaged organs.
Foam silicone rubber. Foam rubber is a hydroxy terminated condensation type silicone rubber as the base, hydroxyl hydrogen silicone oil as a foam, vinyl platinum complex as catalyst (heated catalyst is dibutyltin dilaurate), formed at room temperature vulcanizing a perforated foam sponge-like elastomer. In order to improve the quality of foam also adding some other components, such as those containing silicone to produce more gas curing process; improve the feel and reduce the foam density. Added diphenyl silicone glycol can not only control the foam structure, but also control the compound viscosity increases during storage, but the amount can not be too much, otherwise it will affect the electrical properties of foam. In order to improve the physical and mechanical properties of foam, can also join the transparent silicone rubber. Chloroplatinic acid catalyst the amount of vinyl complex can not be too much to easy to operate subject to, otherwise it would not help increase the viscosity of operation; When the catalyst is insufficient, incomplete curing the bubble surface is sticky, elastic good, with soft plastic, the intensity difference.
Foam liquid silicone rubber vulcanization was before, suitable for potting material. Foam after curing at -60 ~ 159 ℃ for long term, after 150 ℃, 72 hours of aging, or a 70 ℃ 60 ~ 10 10 times the use of alternating hot and cold, foam, remains the original performance. Foam silicone rubber because of high thermal stability, good heat insulation, insulation, moisture, shock resistance, especially in the high frequency of resistance to shock, it is an ideal lightweight packaging materials. For "three defenses" protection. In addition, insulation can also make sandwich filling materials and salt spray atmosphere of floating materials and sealing materials. Foam silicone rubber in medicine can also be used as orthopedic fill, repair and Ying clothing materials. Corning to apply U.S. anti-fire requests transmission lines, develop into a flame-retardant foam at room temperature vulcanized silicone rubber DC3-6548. This foam silicone rubber is mainly used for wire and cable through the Service (such as roof, walls, buildings, holes, etc.) fire seals, fire-retardant properties are very good, limiting oxygen index of 39 (most plastic LOI 20 ), the service life up to 50 years. At present, this flame-retardant foam at room temperature vulcanized silicone rubber is widely used in nuclear power plants, computer centers, offshore oil installations and other harsh environmental conditions, or high fire for special occasions. |
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