High-temperature vulcanized silicone rubber is a high molecular weight (molecular weight is generally 40 ~ 800,000) of polyorganosiloxane (i.e., the raw rubber) to join the reinforcing fillers and other additives, the use of organic peroxides for the vulcanizing agent, the compression molding (molding, extrusion, calendering) or injection molding and cross-linking into a rubber under high temperature. High-temperature crosslinking into rubber. This rubber is generally referred to as silicone rubber.
The vulcanization of high-temperature vulcanized silicone rubber is generally divided into two stages, the first sub-stage is the silicone raw rubber, reinforcing agent, additives, vulcanizing agent and structure control agent for mixing, and then the mixed material in the metal mold pressurized heating molding and vulcanization, the pressure is about 50 kg/cm2, temperature of 120 ~ 130 ℃, time for 10 ~ 30 minutes, the second stage is to be silicone rubber The second stage is to remove the silicone rubber from the mold and put it into the oven at 200 ~ 250 ℃ for several hours to 24 hours. Further vulcanization of the rubber, while the organic peroxide decomposition and volatilization.
Silicone rubber reinforcing filler is a variety of types of silica, which can make the vulcanized rubber strength increased tenfold. Add a variety of additives is mainly to reduce the cost of rubber, improve the performance of the rubber as well as give the vulcanized rubber a variety of special properties such as flame retardant, conductive and so on. Crosslinking agents are various organic peroxides, such as benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dikuuji peroxide, 2,5-di-tert-butyl peroxyhexane and so on. Structure control agent is in order to avoid the mixing of rubber material placed for too long, produce "structuring" to make the rubber material hard hard, difficult to process and add maturity, can use methyl hydroxy silicone oil or diphenyl dihydroxy alkane as a structure control agent.
Silicone rubber side groups on the main chain can be methyl, ethyl, vinyl, phenyl, trifluoropropyl and so on. The most commonly used is methyl, but other groups may be introduced to improve processing and other properties. Therefore, according to the side groups and the formulation of the rubber, you can get a variety of different uses of silicone rubber, generally can be divided into the following types: general-purpose (containing methyl and vinyl), high and low temperature (containing phenyl, methyl and vinyl), low compression set (containing methyl and vinyl), low shrinkage (de-volatilized), and solvent-resistant (fluoro-silicone rubber) and so on. Several important types of silicone rubber are described below.
I. Methyl silicone rubber
Dimethyl silicone rubber is the earliest commercial production of a silicone rubber, can be in the range of -60 ~ 200 ℃ to maintain good elasticity, aging resistance is good, there are excellent electrical insulation properties as well as moisture-proof, shock-proof and physiologically inert and other characteristics.
Dimethyl silicone rubber is mainly used for strong coating, can also be made into a variety of extruded and calendered products for electromechanical, aviation, automotive and medical industries. However, due to the low vulcanization activity of dimethyl silicone rubber, used in the manufacture of thick products, vulcanization difficulties, the inner layer is easy to bubble and high temperature compression permanent deformation, it has been replaced by methyl vinyl silicone rubber.
II. Methyl vinyl silicone rubber
As a result of the introduction of silicone rubber macromolecular structure of a small amount of vinyl can greatly improve the vulcanization of silicone rubber processing performance, so in the current application of silicone rubber, most of which contain vinyl. Methyl vinyl silicone rubber is the most common type of silicone rubber, currently dominates the production of silicone rubber at home and abroad. Due to its introduction of partially unsaturated vinyl on the side chain, so that its processing performance and physical and mechanical properties are better than two-based silicone rubber. In addition to the general characteristics of dimethyl silicone rubber, it also has a wide range of operating temperatures, can be in a 60 ~ 260 ℃ range to maintain good elasticity, it is easier than the dimethyl silicone rubber vulcanization, has a smaller compression permanent deformation, better resistance to solvent expansion and resistance to high pressure steam stability as well as excellent cold resistance, etc., and because of the use of less reactive peroxide for vulcanization, thus reducing the number of Vulcanization of air bubbles and rubber stability weaknesses. Therefore, the general use of methyl vinyl silicone rubber can be made of products with a greater thickness. Methyl vinyl silicone rubber is the most widely used varieties of silicone rubber, in recent years the emergence of a variety of high-performance and special-purpose silicone rubber, most of them are vinyl silicone rubber as the base rubber, such as high-strength silicone rubber, low compression permanent deformation of the silicone rubber, do not need to be vulcanized silicone rubber, heat-resistant, conductive silicone rubber and medical silicone rubber. Methyl vinyl silicone rubber in the aviation industry, widely used as gaskets, sealing materials and fragile, shockproof parts of the protective layer; in the electrical industry can be used as electronic components and other high-level insulating materials, high-temperature potentiometer dynamic seals, underground long-distance communication equipment seals; in medicine, because of the physiological reaction of methyl vinyl silicone rubber on the human body is small, non-toxic, so it is used for surgical orthopedics, artificial heart valves, blood vessels In medicine, due to the small physiological reaction of methyl vinyl silicone rubber to the human body, non-toxic, it is used as surgical plastic surgery, artificial heart valves, blood vessels.
Three. Methyl phenyl vinyl silicone rubber
Methyl phenyl vinyl silicone rubber is the introduction of methyl vinyl silicone rubber in the molecular chain of methyl phenyl silicone oxygen chain or diphenyl silicone oxygen chain and the product. The introduction of phenyl on the side groups of polysiloxanes greatly reduces the crystallization temperature of the polymer by destroying the regularity of the dimethylsiloxane structure, expanding the low-temperature application range of the polymer material. Therefore, methyl phenyl vinyl silicone rubber in addition to all the methyl vinyl silicone rubber compression permanent deformation is small, the use of a wide range of temperatures, oxidation resistance, weather resistance, shockproof, moisture and good electrical insulation properties, but also has excellent resistance to low temperatures, ablative corrosion resistance and irradiation resistance and other properties.... These properties vary with the different phenyl content in the molecular chain, in general, the phenyl content (phenyl and silicon atom ratio) in 5 to 10% called low-phenyl silicone rubber, which has a unique cold-resistant properties in -70 ~ -100 ℃ can still maintain the elasticity of the rubber is the best of all the rubber low-temperature performance of a kind, coupled with both the advantages of methyl vinyl silicone rubber and the cost is not high, so the trend of replacing methyl vinyl silicone rubber. Replacement of methyl vinyl silicone rubber trend. Phenyl content of 20 to 40% called in the phenyl silicone rubber both the advantages of methyl vinyl silicone rubber and the cost is not high, so there is a big trend to replace methyl vinyl silicone rubber. Phenyl content of 20 ~ 40% called in the phenyl silicone rubber, it has excellent flame-resistant properties, once the fire can be self-extinguishing. Phenyl content of 40 ~ 50% called high phenyl silicone rubber, it has excellent radiation resistance, resistance to γ - rays for 1xI08 roentgen. Generally speaking, with the increase of phenyl content, the rigidity of the molecular chain of silicone rubber gradually increased, the low temperature resistance of silicone rubber gradually decreased, but with the increase of phenyl content, improve the vulcanized rubber flame resistance and irradiation resistance. Content from the rubber garden
Methyl phenyl vinyl silicone rubber is the aerospace industry, cutting-edge technology and other sectors of the national economy, one of the important materials, can be used to make a variety of molded and extruded products used as the aviation industry, cold-resistant rubber and used for ablative, heat aging or radiation-resistant parts of the seals, gaskets, tubes and rods, etc..
Four. Fluorosilicone rubber
Fluorosilicone rubber is γ-trifluoropropyl methyl polysiloxane. Fluorosilicone rubber has excellent resistance to chemicals, solvents and lubricants, this silicone rubber in non-polar solvents in the expansion rate is small, cold resistance and thermal stability is good, good resistance to fire, so in the aircraft, rockets, missiles, cosmic flight, petrochemicals, used as fuel oil and lubricating oil contact hose, gaskets, seals, fuel tanks, such as the village, but also used to make corrosion-resistant clothes, gloves and paints, adhesives, etc.. It can also be used to make corrosion-resistant clothes, gloves and paints, adhesives and so on.
V. Nitrile silicone rubber
Since the polymer molecular side chain contains β-carbonitrile ethyl or γ-nitrile propyl strong polar groups, greatly increasing the intermolecular chain force, improve the oil resistance, solvent resistance. At the same time, due to the introduction of a certain amount of nitrile alkyl groups, the regularity of the polymer structure is disrupted, and the cold resistance is also greatly improved. The type of nitrile alkyl and its content, has a great influence on the performance, such as containing 7.5 grams of molecular % γ-carbonitrile propyl silicone rubber, low-temperature performance is similar to the low phenyl silicone rubber (its glass transition temperature of -114.5 ℃), oil resistance is better than phenyl silicone rubber. With γ-carbonitrile propyl content increased to 33-50 grams molecular %, the cold resistance decreased, oil resistance improved. With β-carbonitrile ethyl instead of γ-carbonitrile propyl can improve the heat resistance of nitrile silicone rubber, can withstand 250 ℃ hot air aging.
The main advantage of nitrile silicone rubber is excellent oil resistance and bath agent resistance, can be in the range of -60 ~ 180 ℃ to maintain the elasticity, therefore, can be made into oil-resistant rubber products used in the aviation industry, automotive industry and petroleum industry; can also be used as a high-performance aircraft environmental sealants and tank sealant, at -54 ℃ to 200 ℃ above can maintain the seal. Nitrile silicone rubber can be processed by common equipment.
VI. Styrene-supported silicone rubber
Styrene-supported silicone rubber is mainly characterized by excellent radiation resistance, its radiation resistance for the general-purpose methyl vinyl silicone rubber 10 to 15 times, for the high phenyl silicone rubber, 5 to 10 times, so it can be used in the aerospace industry, the atomic energy industry and nuclear reactors and so on, as the resistance to high-energy radiation of the cables, sheaths, gaskets, as well as heat-shrinkable tubes, and so on.
VII. Ethyl silicone rubber
Diethyl silicone rubber produced by the introduction of ethyl on the side chain of polysiloxane, its outstanding performance is particularly good cold resistance, cold resistance is better than dimethyl silicone rubber and general methyl vinyl silicone rubber. The higher the ethyl content, the better the cold resistance. However, the reactivity of ethyl rubber is greater than that of methyl rubber, so heat resistance decreases as the content of ethyl rubber increases. For ethyl silicone rubber to be used at low temperatures, a polymer containing diethylsiloxane links of 8 grams molecular weight is preferred. The use of ethyl silicone rubber temperature is generally -70 - 200 ℃. Content from the rubber garden
VIII. Silicone nitrogen rubber
Silicone nitrogen rubber's main advantage is that it has excellent thermal stability, in 430 ~ 480 ℃ does not decompose, and some can even withstand high temperatures of more than 500 ℃. Silicone nitrogen rubber's outstanding weakness is poor hydrolytic stability, was once considered to have no future. Later, it was found that the polymers introducing cyclic disilazane in the main chain have good thermal stability. Silicone aromatic support modified with cyclic disilazane-containing elastomers, heated to 425 ℃ in air without weight loss, 570 ℃ when the weight loss is only 10%, and has a good hydrolytic stability. Rubber Information Network, xiangjiaoyuan.com Silicone Rubber Products Introduction to the second-room temperature vulcanization of silicone rubber
Room temperature vulcanization of silicone rubber (RTV) is a new type of silicone elastomers introduced in the sixties, the most notable feature of this rubber is that it can be cured at room temperature without heating, pressurized on the spot, and it is extremely convenient to use. Therefore, as soon as it was introduced, it became an important part of the entire silicone products. Now room temperature vulcanized silicone rubber has been widely used as adhesives, sealants, protective coatings, potting and mold making materials, in all walks of life have its uses. Room temperature vulcanized silicone rubber is known as liquid silicone rubber because of its low molecular weight, and its physical form is usually a flowable fluid or viscous paste with a viscosity between 100 and 1,000,000 centistokes. According to the requirements of use, the rubber before vulcanization can be matched into automatic leveling of the filling material or not flow but can be coated and scraped putty. Room temperature vulcanized silicone rubber filler used with high temperature vulcanized silicone rubber similar to the use of silica reinforcement, so that the vulcanized rubber has 10 to 60 kg / cm2 tensile strength. Fill with different additives can make the rubber has a different specific gravity, hardness, strength, mobility and thixotropy, as well as make the vulcanized rubber has a flame retardant, electrical conductivity, thermal conductivity, ablative resistance and other special properties.
Room temperature vulcanized silicone rubber according to its packaging can be divided into single-component and two-component room temperature vulcanized silicone rubber, according to the vulcanization mechanism can be divided into condensation type and addition molding. Therefore, room temperature vulcanized silicone rubber according to the composition, vulcanization mechanism and the use of different processes can be divided into three major types, namely, single-component room temperature vulcanized silicone rubber, two-component condensation room temperature vulcanized silicone rubber and two-component molding room temperature vulcanized silicone rubber.
One-component and two-component condensation room temperature vulcanization of silicone rubber raw rubber are α,ω-dihydroxy polysiloxane; molding room temperature vulcanization of silicone rubber is containing alkenyl and hydrogen side group (or end group) polysiloxane, because in the ripening, often slightly higher than the room temperature of the case (50 ~ 150 ℃) can achieve good ripening results, so, also known as low-temperature vulcanization of silicone rubber (LTV).
The three series of room temperature vulcanized silicone rubber has its own advantages and disadvantages: one-component room temperature vulcanized silicone rubber has the advantage of ease of use, but the deep curing speed is more difficult; two-component room temperature vulcanized silicone rubber has the advantage of curing is not exothermic, shrinkage is very small, no expansion, no internal stress, curing can be carried out at the same time in the interior and the surface, can be deep vulcanization; plus molding room temperature vulcanized silicone rubber vulcanization time The vulcanization time of additive molding room temperature vulcanization silicone rubber is mainly determined by the temperature, therefore, the use of temperature adjustment can control its vulcanization speed
I. One-component room temperature vulcanized silicone rubber
One-component room temperature vulcanized silicone rubber vulcanization reaction is to rely on the moisture in the air to trigger. Commonly used cross-chaining agent is methyl triacetoxysilane, its Si-O-C bond is easily hydrolyzed, acetoxy and hydrogen in the water combined into acetic acid, and the hydroxyl group in the water to move to the original position of the acetoxy, become three hydroxymethylsilane. Trihydroxymethylsilane is extremely unstable, and it is easy to condense with linear silicone whose end group is hydroxyl to become a cross-chain structure. Normally, the silicone rubber containing silanol end group and fillers, catalysts, crosslinking agents and other agents into a sealed hose, when used by the container extrusion, with the help of moisture in the air and vulcanized into an elastomer, at the same time, the release of low molecular matter. In addition to methyltriacetoxysilane, the cross-linking agent can be a silane containing an alkoxy group, an oxime group, an amine group, an amide group, or a ketone group. When cross-linked with alkoxy alcohol released, known as dehydrogenated one-component room temperature vulcanization of silicone rubber, when cross-linked with oxime generated oxime, known as deoxime room temperature vulcanization of silicone rubber, therefore, with the different crosslinking agent, one-component room temperature vulcanization of silicone rubber can be deacidified, deoximilated, dehydrogenated, deaminated, deamidated and deketonized, and so on, many varieties, but dehydrogenated is one of the most widely used at present.
The vulcanization time of one-component room temperature vulcanized silicone rubber depends on the vulcanization system, temperature, humidity, and the thickness of the silicone rubber layer, and increasing the ambient temperature and humidity can speed up the vulcanization process. In typical environmental conditions, generally 15 to 30 minutes after the surface of the silicone rubber can be no sticky, thickness of 0.3 cm layer can be cured within a day. The depth and strength of cure is gradually enhanced in about three weeks.
One-component room-temperature vulcanized silicone rubber has excellent electrical properties and chemical inertness, as well as heat resistance, natural aging resistance, flame resistance, moisture resistance, breathability and other properties. They can maintain elasticity for a long time in the range of -60 to 200℃. It does not absorb heat or exotherm when curing, has small shrinkage after curing, and has good adhesion to materials. Therefore, it is mainly used as an adhesive and sealant, and other applications include in-situ molding gaskets, protective coatings and inlay materials. Many one-component silicone rubber adhesive formulations exhibit automatic bonding properties to a wide variety of materials such as most metals, glass, ceramics, and coagulation, for example, to bare aluminum, with shear strengths of up to 200 lb/?2 and tear strengths of up to 20 lb? /?2 (0.35 J/cm2). When bonding is difficult, the bond strength can be improved by priming the substrate, which can be a reactive silane monomer or resin that, when cured on the substrate, produces a modified surface suitable for silicone bonding. This article is from the rubber information network
Single-component room temperature vulcanization of silicone rubber, although easy to use, but because of its vulcanization is dependent on the lazy atmospheric moisture, so that the thickness of the vulcanized rubber is limited, can only be used for the need to 6 mm thickness of the following occasions.
One-component room temperature vulcanized silicone rubber vulcanization reaction is gradually from the surface to the depth of the rubber layer, the thicker, the slower the curing. When the deep also want to fast curing, can be used in layers of pouring step by step vulcanization method, each time you can add some rubber, such as vulcanization and then add material, so you can reduce the total vulcanization time. Adding magnesium oxide can accelerate the vulcanization of the deep glue.
Two-component room temperature vulcanized silicone rubber two-component room temperature vulcanized silicone rubber can be divided into condensation type and addition molding.
II. Two-component condensation type room temperature vulcanization silicone rubber
Two-component condensation type room temperature vulcanization silicone rubber is the most common type of room temperature vulcanization silicone rubber, the raw rubber is usually hydroxyl capped polysiloxanes, and then with other agents, catalysts, combined with the composition of the compound, the viscosity of this compound can be from the range of 100 centistokes to one million centistokes between. The vulcanization of two-component room temperature vulcanized silicone rubber is not initiated by moisture in the air, but by a catalyst. Usually, the silicone rubber, filler, and crosslinker are packaged as one component, and the catalyst is packaged separately as another component, or other combinations are used, but the catalyst and crosslinker must be packaged separately. Regardless of the packaging method, only when the two components are completely mixed together, curing will begin to occur. The commonly used crosslinker is ethyl orthosilicate and the catalyst is dibutyltin dilaurate. Appropriate fillers and additives are also added depending on the nature of the desired end product. In recent years, many countries have banned the addition of dibutyltin in food bags and plasma bags due to the fact that dibutyltin dilaurate belongs to the medium toxicity level, and has basically been replaced by the low-toxicity octyltin. Rubber Information Network, xiangjiaoyuan.com
The vulcanization time of two-component condensation type room temperature vulcanized silicone rubber mainly depends on the type of catalyst, the amount of catalyst and the temperature. The higher the amount of catalyst, the faster the vulcanization, while the shorter the shelf time. At room temperature, the shelf time is generally a few hours, if you want to extend the shelf time of the rubber, available cooling method. Two-component condensation type room temperature vulcanization silicone rafter adhesive at room temperature to achieve full curing needs about a day's time, but in the temperature of 150 ℃ only 1 hour. The speed of cure can be significantly increased by using the accelerator γ-aminopropyltriethoxysilane for the synergistic effect. Two-component room temperature vulcanization silicone rubber can be in a 65 ~ 250 ℃ temperature range of long-term elasticity, and has excellent electrical properties and chemical stability, water resistance, ozone resistance, climate aging, coupled with simple usage, process applicability, therefore, widely used as a potting and mold making materials. Various electronic and electrical components with room temperature vulcanized silicone rubber coating, potting, can play a moisture-proof (anti-corrosion, shock and other protective effects.). Can improve performance and stabilize parameters. Two-component room temperature vulcanized silicone rubber is particularly suitable for deep potting materials and has a faster vulcanization time, which is better than one-component room temperature vulcanized silicone rubber.
Two-component room temperature vulcanized silicone rubber vulcanization has excellent anti-adhesive properties, coupled with the vulcanization of the shrinkage rate is very small, so it is suitable for use in the manufacture of soft molds for casting epoxy resins, polyester resins, polystyrene, polyurethanes, vinyl plastics, paraffin waxes, low-melting-point alloys and other molds. In addition, the use of two-component room temperature vulcanized silicone rubber's high simulation performance can be reproduced a variety of exquisite patterns. For example, in the cultural relics reproduction can be used to copy the ancient bronze, in the production of artificial leather can be used to copy the snake, python, crocodile and pangolin and other animal skin pattern, to play the effect of fake to real.
Two-component room temperature vulcanized silicone rubber should pay attention to a few specific issues in use: first of all, the base material, crosslinking agent and catalyst were weighed, and then mixed in proportion. Usually two components should be provided in different colors to use, so that the mixing of the two components can be observed intuitively, the mixing process should be carefully operated in order to minimize the amount of entrapped gas. After mixing the rubber (uniform color), can be removed through the static or decompression (vacuum 700 mm Hg) to remove air bubbles, to be all the air bubbles out, at room temperature or at the specified temperature for a certain period of time that is vulcanized into a silicone rubber.
Two-component room temperature vulcanized silicone rubber silicone rubber main chain of the side groups in addition to methyl, can be replaced with other groups such as phenyl, trifluoropropyl, cyanoethyl, etc., in order to improve its resistance to low temperatures, heat, radiation, or solvent resistance and other properties. At the same time, heat-resistant, flame-retardant, thermally conductive and electrically conductive additives can also be added as needed to produce silicone rubber with ablative, flame-retardant, thermally conductive and electrically conductive properties.
1. Methyl room temperature vulcanized silicone rubber
Methyl room temperature vulcanized silicone rubber for the old varieties of general-purpose silicone rubber, with water resistance, ozone resistance, arc resistance, corona resistance and weather aging and other advantages. It can be used in a 60 ~ 200 ℃ temperature range. Therefore, it is widely used as filling and sealing materials for electronic and electrical components, and filling and sealing materials for moisture-proof, shock-proof, and high and low temperature-resistant instruments and meters. It can also be used to make molds for casting polyester resin, epoxy resin and low melting point alloy parts. It can also be used as dental impression material. With methyl room temperature vulcanized silicone rubber coated in cotton cloth, paper bags, can be made for conveying sticky goods conveyor belts and bags.
2. Methyl biphenyl room temperature vulcanized silicone rubber
Methyl biphenyl room temperature vulcanized silicone rubber in addition to methyl room temperature vulcanized silicone rubber has excellent performance, than the methyl room temperature vulcanized silicone rubber has a wider range of use temperature (-100 ~ 250 ℃). Phenyl content of 2.5-5% of low-phenyl room temperature vulcanized silicone rubber (108-1) can be -120 ℃ at low temperatures to maintain the elasticity of the current silicone rubber in the low-temperature performance of one of the best varieties; phenyl content of 10-20% of the room-temperature rubber (108-2) has a very good resistance to irradiation, ablation and self-extinguishing, if you add a certain amount of heat-resistant additives, such as Fe2O3, and so on, can improve the heat aging performance, suitable for 250 to 250 ℃. Heat aging performance, suitable for use at high temperatures above 250 ℃ or do ablative putty coating and encapsulation materials.
Methyl phenyl room temperature adhesive and other room temperature adhesive, can be used for impregnation, molding and film removal. If you want to increase the adhesion with other materials, you must use the material before the material, the material to be adhered to the surface treatment, surface treatment steps are as follows: acetone solvent on the surface of the material to clean 1 ~ 2 times, and then processed with a surface agent for 1 ~ 2 times in the 60 ℃ oven for a few minutes, this time in the formation of a layer of the surface of the material is less sticky film, can be on the adhesive.
3. Methyl block room temperature vulcanized silicone rubber
Methyl block room temperature vulcanized silicone rubber is methyl room temperature vulcanized silicone rubber modified varieties, it is by the hydroxyl head of polydimethylsiloxane (107 rubber) and methyltriethoxysilane oligomer (molecular weight of 3 ~ 5) **** polymer. Catalyzed by dibutyl tin dilaurate, polydimethylsiloxane in the hydroxyl and polymethyltriethoxysilane in the ethoxy condensation to generate a three-way structure of the polymer, after vulcanization of the elastic to the body than the methyl room-temperature vulcanization of the silicone rubber has a high mechanical strength and adhesive force, can be used for a long period of time in a temperature range of 70 ~ 200 ℃.
Methyl-segmented room temperature vulcanized silicone rubber has shockproof, moisture-proof, waterproof, breathable, ozone-resistant, weather-resistant aging, weak acid and alkali resistance. It has good electrical insulation properties, also has good adhesion, and low cost. Therefore, it can be widely used for potting, coating, molding, stripping, releasing drug carriers and other occasions. Methyl blocking room temperature adhesive potting of electronic components with shockproof, moisture, sealing, insulation, stabilization of various parameters and other functions. Methyl embedded room temperature adhesive directly coated to the speaker, can reduce and eliminate the mid-frequency points of the speaker, after vulcanization of the speaker resonance frequency performance can be reduced by about 20 Hz. In the methyl segmented room temperature adhesive with a certain amount of additives can be used as paper anti-adhesive. In the food industry, candy, cookie conveyor belt coated with a thin layer of methyl blocking room temperature adhesive, can improve the anti-adhesive properties of canvas, thus improving the appearance of food, improve the utilization of raw materials. Content from the rubber garden
In the methyl segmented room temperature adhesive by adding the appropriate amount of gas phase method of silica, can be used for the installation of window glass, curtain walls, window frames, prefabricated panels of the joints, the expansion joints of the airport runway. In addition, it can also be used as an adhesive for magnetic cores and templates in electronic computer memory, and as an adhesive for conductive silicone rubber and non-conductive silicone rubber. Methyl-segmented room temperature vulcanized silicone rubber treatment of fabrics can improve the feel of the fabric, softness and resistance to curved abrasion.
4. Room temperature vulcanization of nitrile silicone rubber
Room temperature vulcanization of nitrile silicone rubber is a poly β-carbonitrile ethyl methicone silicone, room temperature vulcanization of guessing silicone rubber in addition to silicone rubber light, ozone, moisture, high and low temperatures and excellent electrical insulation properties, the main feature is the resistance to non-polar solvents, such as aliphatic, aromatic solvents, good performance, and the performance of its oil and ordinary oil-resistant NBR is close to the oil-resistant, can be used as oil-contaminated parts and oil-resistant NBR, and can be used as an oil contamination parts and oil-resistant NBR. It can be used as sealing material for oil pollution parts and oil resistant electronic components.
5. Room temperature vulcanized fluorosilicone rubber
Room temperature vulcanized fluorosilicone rubber is a polyγ-trifluoropropylmethylsiloxane, which is mainly characterized by fuel oil resistance, solvent resistance and high temperature anti-degradation properties, but also has a good performance of extrusion. Mainly used for supersonic aircraft overall fuel tank sealing, embedded seams, fluorosilicone rubber gaskets, gasket bonding fixed; silicone rubber and fluorosilicone rubber bonding, as well as chemical engineering and general industry fuel oil resistant; solvent resistant parts of the bond.
6. Room temperature vulcanization benzene-supported silicone rubber
Room temperature vulcanization benzene-supported silicone rubber is silicone benzene (biphenyl) supported siloxane polymer, its outstanding advantage is that it has excellent resistance to high-energy rays. Tests have proved that after 1x109 roentgen γ-rays or 1xl018 neutrons / cm2 neutron irradiation, can still maintain the elasticity of the rubber, than the room temperature vulcanization of methyl silicone rubber is 10 to 15 times larger than the room temperature vulcanization of phenyl silicone rubber is 5 to 10 times larger than the room temperature vulcanization of phenyl silicone rubber.
Room temperature vulcanization phenyl silicone rubber can be applied to the atomic energy industry, nuclear power devices and space flight as high temperature, radiation-resistant adhesive sealing materials and motor insulation layer.
Three. Add molding room temperature vulcanization silicone rubber
Two-component add molding room temperature vulcanization silicone rubber has elastic silicone gel and silicone rubber, the former lower strength, the latter higher strength. Their vulcanization mechanism is based on the silicone raw rubber end group on the vinyl (or propylene-based) and crosslinking agent molecules on the silicone hydrogen-based addition reaction (hydrosilylation reaction) to complete.
In this reaction, hydride-functional polysiloxanes are used as cross-linkers (vulcanizing agents) and chloroplatinic acid or other soluble platinum compounds are used as catalysts. The vulcanization reaction is carried out at room temperature. No by-products are released. Since the crosslinking process does not release low molecules, additive molding room temperature vulcanized silicone rubber in the vulcanization process does not produce shrinkage. This type of vulcanized rubber is non-toxic, high mechanical strength, excellent hydrolysis resistance stability (even under high pressure steam), good low compression deformation, low combustibility, can be deep vulcanization, as well as the speed of vulcanization can be controlled by the temperature and so on, so it is a class of domestic and foreign vigorously developed silicone rubber.
Addition of room temperature vulcanization of silicone rubber packaging is generally divided into M, N two components for packaging: the catalyst and vinyl-containing silicone polymers as a component of the energetic group; hydrogen-containing polysiloxane crosslinking agent as another component.
High-strength molding room temperature vulcanized silicone rubber due to low line shrinkage, vulcanization does not release low molecules, so it is an excellent material for mold making. In the machinery industry has been widely used in the mold to casting epoxy resin, polyester resin, polyurethane, polystyrene, vinyl plastics, paraffin, low melting point alloys, coagulation and so on. The use of additive molding choking temperature vulcanization of silicone rubber high simulation, no corrosion, molding process is simple, easy to take off the mold and other characteristics, suitable for cultural relics reproduction and reproduction of fine arts and crafts. Please remember our website:Rubber Garden
Silicone rubber products introduced three-silicone gel
Plasticizing room temperature vulcanization of silicone rubber for the colorless or yellowish transparent oily liquid, vulcanized into a soft transparent silicone gel. This gel can be in the -65 ~ 200 ℃ temperature range of long-term elasticity, it has excellent electrical properties and chemical stability, water resistance, ozone resistance, weather aging, water repellent, moisture-proof, shockproof, non-corrosive, and has the advantages of physiological inertia, non-toxic, tasteless, easy to perfusion, can be deep vulcanization, low line shrinkage, easy to operate, etc., Silicone gel in the electronics industry is widely used as an electronic components Moisture-proof, smuggling, insulation coating and potting materials, electronic components and assemblies of dust-proof, moisture-proof, shockproof and insulation protection. Such as the use of transparent gel potting electronic components, not only can play a role in shockproof waterproof protection, but also can see the components and can be detected with a probe component failure, replacement, damage to the silicone gel can be again potting repair.
Silicone gel due to high purity, easy to use, and a certain degree of elasticity, so it is an ideal transistors and integrated circuits within the coating material, can improve the qualification rate of semiconductor devices and reliability; silicone gel can also be used as an elastic adhesive for optical instruments.
In the medical silicone gel can be used as implanted organs such as artificial breasts, and used to repair damaged organs.
Foam silicone rubber. Foam silicone rubber is a condensed hydroxyl sealing end of the silicone rubber as the base material, hydroxyl hydrogen silicone oil for the foaming agent, vinyl platinum complex for the catalyst (heating catalyst for the dibutyl tin dilaurate), vulcanized at room temperature foaming a spongy spongy elastomer. In order to improve the quality of the foam body should also add some other components, such as containing silicone oil, so that the vulcanization process produces more gas; improve the feel of the foam body and reduce the density. The addition of diphenylsilanediol can not only control the structure of the foam body, but also control the viscosity of the rubber material in the storage process, but its dosage can not be too much, otherwise it will affect the electrical properties of the foam body. In order to improve the physical and mechanical properties of the foam body, can also be added transparent silicone rubber. The dosage of vinyl complex of catalyst chloroplatinic acid can not be too much, subject to the convenience of operation, otherwise it will make the viscosity increase unfavorable to the operation; when the dosage of catalyst is insufficient, the vulcanization is incomplete, and the surface of the foam body is sticky, elasticity is not good, soft with plasticity, and the strength is poor. copyright Rubber Information Network
Foam silicone rubber is liquid before vulcanization, suitable for potting materials. After vulcanization of the foam body can be used at -60 ~ 159 ℃ for a long time, by 150 ℃, 72 hours of aging, or a 60 ~ 70 ℃ ten times the use of hot and cold alternation, the foam body still maintains the original performance. Foam silicone rubber due to high thermal stability, good thermal insulation, insulation, moisture resistance, shock resistance, especially in the high-frequency shock resistance, so it is an ideal lightweight packaging materials. It is used for "three-proof" protection. In addition, it can also be used as filler material for adiabatic interlayer and floating material in salt spray atmosphere as well as sealing material. Foam silicone rubber in medicine can also be used as orthopedic filling, repair and clothing materials. The United States in order to apply the fire protection requirements of the transmission lines, developed into a flame-retardant room temperature vulcanization foam silicone rubber DC3-6548, this foam silicone rubber is mainly used for wire and cable through the place (such as roofs, walls, buildings, etc. at the holes) of the fire sealing, flame retardant performance is very good, its limit oxygen index of 39 (the majority of plastics limit oxygen index is only 20), the service life of up to 50 years. Its ultimate oxygen index is 39 (most plastics have an ultimate oxygen index of only 20) and its service life is up to 50 years. At present, this flame retardant room temperature vulcanization foam silicone rubber has been widely used in nuclear power plants, computer centers, offshore oil recovery devices and other harsh environmental conditions, or fire prevention requirements of particularly high field
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