I suggest you buy a copy of "High Temperature (Room Temperature) Vulcanized Silicone Rubber Market Research Report"
Here: /07.asp?id=1150, but I think the version is older. The price/performance ratio is not high, so it’s better to just look at the project.
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Introduction to room temperature vulcanized silicone rubber (RTV)
Room temperature vulcanized silicone rubber (RTV) is a new type of silicone elastomer that came out in the 1960s. The most significant feature of this rubber is that it does not require heating at room temperature. , it can be cured on the spot by applying pressure and is extremely convenient to use. Therefore, it has become an important part of the entire silicone product as soon as it comes out. Room temperature vulcanized silicone rubber is now widely used as adhesives, sealants, protective coatings, potting and molding materials, and has its uses in various industries. Room temperature vulcanized silicone rubber is known as liquid silicone rubber due to its low molecular weight. 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 pre-vulcanized rubber can be made into self-leveling potting material or putty that does not flow but can be scratched. The fillers used in room temperature vulcanized silicone rubber are similar to high temperature vulcanized silicone rubber, and are reinforced with white carbon black to give the vulcanized rubber a tear strength of 10 to 60 kg/cm2. Adding different additives can make the rubber material have different specific gravity, hardness, strength, fluidity and thixotropy, and make the vulcanized rubber have various special properties such as flame retardant, electrical conductivity, thermal conductivity, and ablation resistance.
Room temperature vulcanized silicone rubber can be divided into single-component and two-component room temperature vulcanized silicone rubber according to its packaging method. According to the vulcanization mechanism, it can be divided into condensation type and addition type. Therefore, room temperature vulcanized silicone rubber can be divided into three major types according to different compositions, vulcanization mechanisms and usage processes, namely single-component room temperature vulcanized silicone rubber, two-component condensation type room temperature vulcanized silicone rubber and two-component addition type room temperature vulcanized silicone rubber. .
The raw rubber of one-component and two-component condensation room temperature vulcanization silicone rubber are α,ω-dihydroxypolysiloxane; the addition type room temperature vulcanization silicone rubber contains alkenyl and hydrogen side Polysiloxane with base (or end group), because during curing, good curing effect can often be achieved at a temperature slightly higher than room temperature (50~150℃), so it is also called low temperature vulcanized silicone rubber (LTV) .
These three series of room temperature vulcanized silicone rubber each have their own advantages and disadvantages: the advantage of one-component room temperature vulcanized silicone rubber is that it is easy to use, but the deep curing speed is difficult; the two-component room temperature vulcanized silicone rubber has The advantage is that it does not release heat during curing, has a very small shrinkage, does not expand, and has no internal stress. Curing can be performed both internally and on the surface at the same time, and can be deeply vulcanized. The vulcanization time of addition type room temperature vulcanized silicone rubber mainly depends on the temperature. Therefore, using Temperature adjustment can control the vulcanization speed.
1. One-component room temperature vulcanized silicone rubber
The vulcanization reaction of one-component room temperature vulcanized silicone rubber is initiated by moisture in the air. The commonly used cross-linking agent is methyltriacetoxysilane. Its Si-O-C bond is easily hydrolyzed. The acetoxy group combines with the hydrogen group in the water to form acetic acid, and the hydroxyl group in the water is moved to the original acetoxy group. position, it becomes trihydroxymethylsilane. Trihydroxymethylsilane is extremely unstable and easily condenses with linear silicone with hydroxyl end groups to form a cross-linked structure. Usually, the organic silicone rubber containing silanol end groups and various compounding agents such as fillers, catalysts, and cross-linking agents are put into a sealed hose. When used, it is extruded from the container and vulcanized with the help of moisture in the air. Elastomers also release low molecular weight substances. In addition to methyltriacetoxysilane, the cross-linking agent can also be a silane containing an alkoxy group, an oxime group, an amine group, an amide group, or a ketone group. When it is cross-linked with an alkoxy group and releases alcohol, it is called a dealcoholized one-component room temperature vulcanized silicone rubber. When it is cross-linked with an oxime group, an oxime is generated, which is called a deoxime type room temperature vulcanized silicone rubber. Therefore, with the cross-linking Depending on the agent, single-component room temperature vulcanized silicone rubber can be of many varieties such as deacidification type, deoxime type, dealcoholization type, deamination type, deamidation type and deketone type, but the deacidification type is currently the most widely used. A sort of.
The vulcanization time of one-component room temperature vulcanized silicone rubber depends on the vulcanization system, temperature, humidity and thickness of the silicone rubber layer. Increasing the temperature and humidity of the environment can speed up the vulcanization process. Under typical environmental conditions, generally after 15 to 30 minutes, the surface of the silicone rubber can become non-sticky, and a 0.3 cm thick adhesive layer can be cured within one day. The depth and strength of the cure gradually builds up over 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 -60~200℃. It does not absorb or release heat when curing, has a small shrinkage after curing, and has good adhesion to materials. Therefore, it is mainly used as adhesives and sealants, but other applications include form-in-place gaskets, protective coatings and caulking materials. Many one-component silicone rubber adhesive formulations exhibit self-bonding properties on a variety of materials such as most metals, glass, ceramics and concrete, such as bare aluminum, with shear strengths up to 200 lb/in. 2. The tear strength can reach 20 pounds·feet/inch2 (0.35 Joules/cm2).
When bonding is difficult, a primer can be applied on the base material to improve the bonding strength. The primer can be a reactive silane monomer or resin. When they are cured on the base material, a layer of modified suitable on silicone bonded surfaces.
Although single-component room temperature vulcanized silicone rubber is easy to use, its vulcanization depends on moisture in the atmosphere, so the thickness of the vulcanized rubber is limited and can only be used in situations requiring a thickness of less than 6 mm. .
The vulcanization reaction of one-component room temperature vulcanized silicone rubber proceeds gradually from the surface to the depth. The thicker the rubber layer, the slower the curing. When the deep part needs to be cured quickly, the layered pouring and gradual vulcanization method can be used. Some rubber can be added each time and then added after vulcanization, which can reduce the total vulcanization time. Adding magnesium oxide can accelerate the vulcanization of deep glue.
Two-component room temperature vulcanized silicone rubber. Two-component room temperature vulcanized silicone rubber can be divided into condensation type and addition type.
2. 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, and its raw rubber is usually Hydroxyl-terminated polysiloxane is combined with other ingredients and catalysts to form a rubber compound. The viscosity of this rubber compound can range from 100 centistokes to one million centistokes. The vulcanization reaction of two-component room temperature vulcanized silicone rubber is initiated not by moisture in the air, but by a catalyst. Usually, the silica gel, filler, and cross-linking agent are packaged as one component, and the catalyst is packaged separately as another component, or other combinations are used, but the catalyst and cross-linking agent must be packaged separately. Regardless of the packaging method, curing begins to occur only when the two components are completely mixed together. The commonly used cross-linking agent is ethyl orthosilicate, and the catalyst is dibutyltin dilaurate. And add appropriate fillers and additives based on the properties of the desired final product. In recent years, many countries have banned the addition of dibutyltin in food bags and plasma bags because dibutyltin dilaurate is a medium-toxic substance. It has been basically replaced by low-toxic octyltin.
The vulcanization time of two-component condensation room temperature vulcanized silicone rubber mainly depends on the type, dosage and temperature of the catalyst. The more catalyst used, the faster the sulfurization will be, and the shorter the storage time will be. At room temperature, the storage time is usually a few hours. If you want to extend the storage time of the rubber, you can use the cooling method. It takes about a day for two-component condensation type room temperature vulcanized silicone rafter glue to fully cure at room temperature, but it only takes 1 hour at a temperature of 150°C. The curing speed can be significantly increased through the synergistic effect of the accelerator γ-aminopropyltriethoxysilane. Two-component room temperature vulcanized silicone rubber can maintain elasticity for a long time in the temperature range of 165 to 250°C, and has excellent electrical properties and chemical stability. It is resistant to water, ozone, and weather aging. In addition, it is simple to use and has strong process applicability. , therefore, widely used as potting and molding materials. After coating and potting various electronic and electrical components with room temperature vulcanized silicone rubber, they can protect against moisture (anti-corrosion, shockproof, etc.) and can improve performance and stability parameters. Two-component room temperature vulcanized silicone rubber is particularly suitable for deep potting The sealing material has a faster vulcanization time, which is superior to single-component room temperature vulcanized silicone rubber.
Two-component room temperature vulcanized silicone rubber has excellent anti-stick properties after vulcanization. The shrinkage rate during vulcanization is extremely small, so it is suitable for making soft molds for casting epoxy resin, polyester resin, polystyrene, polyurethane, vinyl plastic, paraffin, low melting point alloy, etc. In addition, it is used. The high simulation performance of two-component room temperature vulcanized silicone rubber can reproduce various exquisite patterns. For example, it can be used to reproduce ancient bronzes in the reproduction of cultural relics, and can be used to reproduce the skin patterns of snakes, pythons, crocodiles, pangolins and other animals in the production of artificial leather. , which has the effect of confusing fakes with real ones.
When using two-component room temperature vulcanized silicone rubber, you should pay attention to several specific issues: first, weigh the base material, cross-linking agent and catalyst separately, and then mix them in proportion. Usually the two components should be provided in different colors so that the mixing of the two components can be visually observed. The mixing process should be carefully operated to minimize the amount of trapped gas. ), the bubbles can be removed by standing still or decompressing (vacuum degree 700 mmHg). After all the bubbles are discharged, it can be vulcanized into silicone rubber by leaving it at room temperature or at a specified temperature for a certain period of time.
In addition to the methyl group, the side groups on the main chain of the two-component room temperature vulcanized silicone rubber siloxane can be replaced with other groups such as phenyl, trifluoropropyl, cyanoethyl, etc. to improve its low temperature resistance and resistance to Heat resistance, radiation resistance or solvent resistance. At the same time, heat resistance, flame retardant, thermal conductivity, and electrical conductivity additives can be added as needed to produce silicone rubber with ablation resistance, flame retardancy, thermal conductivity, and electrical conductivity. p>
1. Methyl room temperature vulcanized silicone rubber
Methyl room temperature vulcanized silicone rubber is an old variety of general-purpose silicone rubber. It is water-resistant, ozone-resistant, arc-resistant, corona-resistant and weather-aging resistant. and other advantages. It can be used in a temperature range of 60 to 200°C. Therefore, it is widely used as a filling and sealing material for electronic and electrical components. It can also be used to make molds for moisture-proof, shock-proof, and high-temperature resistant filling and sealing materials. , used for casting polyester resin, epoxy resin and low melting point alloy parts. It can also be used as dental impression material. It can be coated with methyl room temperature vulcanized silicone rubber on cotton cloth and paper bags for transportation. Conveyor belts and bags for sticky items.
2. Methyl diphenyl room temperature vulcanized silicone rubber
In addition to the excellent properties of methyl diphenyl room temperature vulcanized silicone rubber, methyl diphenyl room temperature vulcanized silicone rubber is better than methyl diphenyl room temperature vulcanized silicone rubber. Room temperature vulcanized silicone rubber has a wider operating temperature range (-100~250℃). Low phenyl room temperature vulcanized silicone rubber (108-1) with a phenyl content of 2.5 to 5% can maintain elasticity under low temperature conditions of -120°C. It is currently the best low-temperature performance variety of silicone rubber; the phenyl content is 10 ~20% room temperature glue (108-2) has good radiation resistance, ablation resistance and self-extinguishing properties. If a certain amount of heat-resistant additives such as Fe2O3 are added to it, the thermal aging performance can be improved, and it is suitable for 250 Used at high temperatures above ℃ or used as ablation-resistant putty coatings and encapsulating materials.
Methyl phenyl room temperature adhesive, like other room temperature adhesives, can be used for dipping, impression and release. If you want to increase the adhesion with other materials, you must perform surface treatment on the adhered material before using the material. The surface treatment steps are as follows: Clean the surface of the material 1 to 2 times with acetone solvent, and then treat it with a surface agent 1 ~2 times, bake in a 60°C oven for a few minutes. At this time, a layer of less sticky film will be formed on the surface of the material, and the glue can be applied.
3. Methyl block room temperature vulcanization silicone rubber
Methyl block room temperature vulcanization silicone rubber is a modified variety of methyl room temperature vulcanization silicone rubber. It is capped by a hydroxyl group It is a polymer of polydimethylsiloxane (107 gum) and methyltriethoxysilane oligomer (molecular weight 3 to 5). Under the catalysis of dibutyltin dilaurate, the hydroxyl groups in polydimethylsiloxane and the ethoxy groups in polymethyltriethoxysilane are condensed to form a three-dimensional polymer. After vulcanization, the elastic The silicone rubber has higher mechanical strength and adhesive force than methyl room temperature vulcanization silicone rubber, and can be used for a long time in a temperature range of 70 to 200°C.
Methyl block room temperature vulcanized silicone rubber has the properties of shockproof, moisture-proof, waterproof, breathable, ozone resistance, weather aging resistance, and resistance to weak acids and weak alkali. It has good electrical insulation properties, good adhesive properties, and is low cost. Therefore, it can be widely used in potting, coating, impression, demoulding, drug carrier release and other occasions. Electronic components potted with methyl block room temperature adhesive have the functions of shockproof, moisture-proof, sealing, insulation, and stabilization of various parameters. Applying methyl block room temperature glue directly to the speaker can reduce and eliminate the mid-frequency points of the speaker. After vulcanization, the resonant frequency performance of the speaker can be reduced by about 20 Hz. After adding a certain amount of additives to the methyl block room temperature adhesive, it can be used as a paper anti-sticking agent. After applying a thin layer of methyl block room temperature adhesive on the candy and biscuit conveyor belts in the food industry, the anti-stick properties of the canvas can be improved, thereby improving the appearance of the food and increasing the utilization rate of raw materials.
Add an appropriate amount of fumed silica to the methyl block room temperature adhesive, which can be used to install window glass, curtain walls, window frames, seams of prefabricated panels, and expansion joints of airport runways. In addition, it can also be used as an adhesive for magnetic cores and templates in electronic computer memories, and as an adhesive for conductive silicone rubber and non-conductive silicone rubber. Treating fabrics with methyl block room temperature vulcanized silicone rubber can improve the fabric's feel, softness and bending resistance.
4. Room temperature vulcanized nitrile silicone rubber
Room temperature vulcanized nitrile silicone rubber is polyβ-nitrile ethyl methyl siloxane. Room temperature vulcanized silicone rubber has the light resistance of silicone rubber. In addition to its resistance to ozone, moisture resistance, high and low temperature resistance and excellent electrical insulation properties, its main feature is its resistance to non-polar solvents such as aliphatic and aromatic solvents. Its oil resistance is close to that of ordinary oil-resistant nitrile rubber and can be used Used for sealing and filling of oil-contaminated parts and oil-resistant electronic components.
5. Room temperature vulcanized fluorosilicone rubber
Room temperature vulcanized fluorosilicone rubber is polyγ-trifluoropropylmethylsiloxane. Its main feature is that it is resistant to fuel oil, Resistant to solvents and high temperature degradation, and also has good extrusion properties. Mainly used for sealing and caulking of the overall fuel tank of supersonic aircraft, fluorosilicone rubber gaskets, and gasket bonding and fixation; bonding of silicone rubber and fluorosilicone rubber, as well as fuel oil resistance and solvent resistance parts in chemical engineering and general industry of bonding.
6. Room temperature vulcanization phenylene silicone rubber
Room temperature vulcanization phenylene silicone rubber is a silophenyl (biphenyl) siloxane polymer. Its outstanding advantage is that it has excellent Resistant to high-energy radiation. Tests have proven that after being irradiated by 1x109 Roentgen γ-rays or 1x1018 neutrons/cm2, the rubber can still maintain elasticity, which is 10 to 15 times greater than room temperature vulcanization methyl silicone rubber and 5 to 5 times greater than room temperature vulcanization phenyl silicone rubber. 10 times.
Room temperature vulcanized phenylene silicone rubber can be used in the atomic energy industry, nuclear power plants, and spaceflight as high-temperature and radiation-resistant adhesive sealing materials and insulating protective layers for motors.
3. Addition room temperature vulcanized silicone rubber
Two-component addition room temperature vulcanized silicone rubber is divided into elastic silicone gel and silicone rubber. The former has lower strength and the latter has higher strength. higher. Their vulcanization mechanism is based on the addition reaction (hydrosilylation reaction) between the vinyl group (or propylene group) on the silicone rubber end group and the silicon hydrogen group on the cross-linking agent molecule.
In this reaction, hydride-functional polysiloxane is used as a cross-linking agent (vulcanizing agent) and chloroplatinic acid or other soluble platinum compounds are used as catalysts. The vulcanization reaction takes place at room temperature. No by-products are released.
Since no low molecular weight substances are released during the cross-linking process, addition type room temperature vulcanization silicone rubber does not shrink during the vulcanization process. This type of vulcanized rubber is non-toxic, has high mechanical strength, has excellent hydrolysis resistance (even under high-pressure steam), good low compression deformation, low flammability, can be deeply vulcanized, and the vulcanization speed can be controlled by temperature, etc. Advantages, so it is a type of silicone rubber currently being vigorously developed at home and abroad.
The packaging method of addition room temperature vulcanized silicone rubber is generally divided into two components: M and N: the catalyst and the silicone polymer containing vinyl energetic groups are used as one component; A hydrogen polysiloxane cross-linker is used as another component.
High-strength addition type room temperature vulcanized silicone rubber has a low linear shrinkage and does not release low molecules during vulcanization, so it is an excellent material for molding. It has been widely used in the machinery industry to make molds to cast epoxy resin, polyester resin, polyurethane, polystyrene, vinyl plastics, paraffin, low melting point alloys, concrete, etc. Utilizing the characteristics of high simulation, non-corrosion, simple molding process, and easy demoulding of addition-type thermally vulcanized silicone rubber, it is suitable for the reproduction of cultural relics and art crafts.
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Project Introduction
This technology includes:
1. Use dimethyldichlorosilane hydrolyzate as raw material, crack it into rings and water, and then dry it to obtain DMC.
2. HTV raw rubber is obtained by ring-opening polymerization of DMC, VMC and vinyl-terminated low-viscosity silicone oil as raw materials. The required equipment, static mixer and low molecular weight remover, has independent intellectual property rights.
3. HTV raw rubber, white carbon black and additives are mixed in a kneader to obtain the finished mixed rubber.
Chenguang Institute has a series of process technologies with single-machine production capacity from 150 tons to 5,000 tons. This technology has been successfully transferred at home and abroad, and 90% of domestic HTV raw rubber production is produced using this technology. The three wastes produced by this production line are potassium siloxanolate, trimethylamine and methanol. The amount of potassium siloxanolate generally accounts for 1‰ to 2‰ of the weight of the hydrolyzate. The annual emissions of trimethylamine and methanol are about 60kg and 30kg respectively (based on a 1500t/a scale), which are not enough to cause a major impact on the environment. The cyclic bodies released after dehydration and low molecular weight removal can be returned and used as raw materials.
Product application fields
Hot vulcanized silicone rubber (HTV) is a type of silicone product with the largest output and wide application. Reinforcing fillers, vulcanizing agents and other additives are added to hot vulcanized silicone rubber raw rubber, and mixed rubber is formed. It can be processed into various silicone rubber products by general rubber processing methods such as molding and extrusion. Silicone rubber has excellent high and low temperature resistance and can be used for a long time in the range of -60 to 250°C. It also has excellent electrical insulation properties, is resistant to ozone, weather aging, hydrophobic, moisture-proof, and has good physiological inertness. Therefore, it is widely used in aerospace, aviation, electronics, electrical, construction, machinery, metallurgy, automobiles, instrumentation, textile, chemical industry, light industry, food, medicine and health and other sectors. Especially in the field of electronics and electrical, such as conductive buttons for computers, calculators, telephones, etc., insulation layers for wires and cables, insulators for high-voltage transmission lines, lightning arresters, various gaskets, various sealing rings for automobiles, etc.
Market prospects
The production and consumption of silicone rubber in developed countries in the world have reached a very high level and are developing very rapidly. The world's consumption of hot vulcanized silicone rubber compounds in 1995 was 125,000 tons. Mainland China's production capacity of hot vulcanized silicone rubber raw rubber in 1995 was approximately 9,000 tons, and the country produced nearly 5,000 tons of raw rubber and 7,000 tons of mixed rubber. Due to the rapid development of China's silicone rubber products industry in recent years, mainland China also imported more than 5,000 tons of silicone rubber compound in 1995. Therefore, mainland China's consumption of silicone rubber compounds accounts for about 10% of world consumption. Currently, the demand for hot vulcanized silicone rubber is about 15,000 tons/year.
Investment status
All or part of this technology can be transferred. Investment status can be discussed in person.
Company name: Zhonglan Chenguang Chemical Research Institute
Contact person: Ping Lei Chen Yan
Telephone: 86-28-85533217
Email: cgrici@hotmail.com