Open classification: silicone rubber, silica gel, fine pore silica gel, inorganic silica gel and silica gel desiccant.
Basic information
Name: silica gel
Alias: silicone rubber
English name: silicon dioxide
English alias: silica gel; silicon dioxide
Molecular formula: H2O3Si
Molecular weight: 60.08
CAS login number: 763 1-86-9
EINECS login number: 23 1-545-4.
Explanation of words: chemical formula xsio2 yh2o. Transparent or milky granular solid. It has an open porous structure and strong adsorption capacity, and can adsorb a variety of substances. If water is absorbed, the moisture absorption is about 40%. If cobalt chloride is added, it will be blue after drying and red after absorbing water. Renewable and reusable.
Generally speaking, silica gel can be divided into organic silica gel and inorganic silica gel according to its nature and composition.
Inorganic silica gel is a highly active adsorption material, which is usually prepared by a series of post-treatment processes such as reaction of sodium silicate with sulfuric acid, aging, acid bubble and so on. Silica gel is an amorphous substance with the chemical molecular formula of msio2.nh2o. It is insoluble in water and any solvent, non-toxic, tasteless, chemically stable, and does not react with any substance except strong alkali and hydrofluoric acid. Due to different manufacturing methods, various types of silica gel have different microporous structures. The chemical composition and physical structure of silica gel determine that it has many irreplaceable characteristics: high adsorption performance, good thermal stability, stable chemical properties and high mechanical strength.
Silica gel is divided into macroporous silica gel, coarse silica gel, B-type silica gel and fine silica gel according to pore size. Because of the different pore structures, their adsorption properties have their own characteristics. Macroporous silica gel has higher adsorption capacity at high relative humidity, while microporous silica gel has higher adsorption capacity at low relative humidity, while type B silica gel has a pore structure between coarse pores and fine pores, and its adsorption capacity is also between coarse pores and fine pores. Macroporous silica gel is generally used as catalyst carrier, matting agent, toothpaste abrasive and so on. Therefore, different varieties should be selected according to different uses.
safety performance
The main component of silica gel is silica, which is chemically stable and does not burn. Silica gel is an amorphous silica, and the dust content in the workshop should be controlled at no more than 10 mg/m3. Strengthen ventilation and wear a mask when operating.
Silica gel has strong adsorption capacity and can dry human skin. Therefore, work clothes should be worn when operating. If silica gel enters the eyes, it should be washed with plenty of water and treated by a doctor as soon as possible.
Blue silica gel is toxic because it contains a small amount of cobalt chloride, so contact with food and inhalation should be avoided. In case of poisoning, you should seek medical attention immediately.
Silica gel can be reused after regeneration because it absorbs water vapor or other organic substances in the medium.
First, the regeneration of silica gel after absorbing water vapor.
After silica gel absorbs water, it can be removed by thermal desorption. There are many heating methods, such as electric heating furnace, flue waste heat heating and hot air drying.
The temperature for removing additional heat should be controlled at 120- 180℃, and the blue gel indicator, color-changing silica gel and DL type blue silica gel should be controlled at 100- 120℃. The maximum temperature during the regeneration of various industrial silica gels shall not exceed the following limits:
Coarse pore silica gel shall not be higher than 600℃;
Fine pore silica gel shall not be higher than 200℃;
Blue gel indicator (or color-changing silica gel) shall not be higher than120℃;
Silicone-aluminum adhesive shall not be higher than 350℃.
The water content of regenerated silica gel can be controlled below 2% and can be put into use again.
The second is the regeneration of silica gel after adsorption of organic impurities.
1. Baking method
For coarse porous silica gel, it can be put into a drying furnace and gradually heated to 500-600℃, which takes about 6-8 hours until the colloidal particles are white or yellowish brown. For fine pore silica gel, the calcination temperature should not exceed 200℃.
2. Washing method
After saturated adsorption in saturated steam, silica gel is soaked and rinsed in exothermic water, which can be used with detergent to remove waste oil or other organic impurities, then washed with clear water, dried and dehydrated.
3. Solvent washing method
Accord to that types of organic substance adsorbed by silica gel, an appropriate solvent is selected to dissolve the organic substances adsorb in the silica gel, and then the silica gel is heated to remove the solvent.
Three, silica gel regeneration should pay attention to the problem
1. In the process of drying and regeneration, attention should be paid to gradually increasing the temperature to avoid the bursting of colloidal particles due to severe drying and reduce the recovery rate.
3. When silica gel is roasted and regenerated, high temperature will change the pore structure of silica gel, obviously reduce its adsorption effect and affect its use value. For blue gel indicator or color-changing silica gel, the desorption regeneration temperature should not exceed 65438 0 20℃, otherwise the color-developing effect will be lost due to the gradual oxidation of the color-developing agent.
3. In general, the regenerated silica gel should be screened to remove fine particles and make the particles uniform.
Storage and packaging
Silica gel has strong hygroscopicity and should be stored in a dry place. There should be a shelf between the package and the ground. Packaging materials include steel drums, paper drums, cartons, plastic bottles, polyethylene plastic composite bags and flexible container bags. Avoid rain, damp and exposure during transportation. Shandong Xinhua Silica Gel: www.xinxuchem.com
silica gel
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The basic structural unit of silicone rubber products is composed of siloxane chains, and the side chains are connected with other organic groups through silicon atoms. Therefore, the structure of silicone products contains both "organic groups" and "inorganic structures". This special composition and molecular structure make it have both the characteristics of organic matter and the functions of inorganic matter. Compared with other polymer materials, the most outstanding features of silicone products are:
1. Temperature resistance characteristics
Silicone products have silicon-oxygen (Si-O) bond as the main chain structure. The bond energy of C-C bond in siloxane is 82.6 kcal/mol, and that of Si-O bond is 65,438+0,265,438+0 kcal/mol. Therefore, silicone products have high thermal stability, and the chemical bonds of molecules will not break or decompose under high temperature (or radiation irradiation). Silica gel is not only resistant to high temperature, but also to low temperature, and can be used in a wide temperature range. The chemical properties and physical and mechanical properties do not change much with temperature.
2. Weather resistance
The main chain of silicone products is -Si-O-, and there is no chemical bond, so it is not easily decomposed by ultraviolet rays and ozone. Silicone has better thermal stability, radiation resistance and weather resistance than other polymer materials. The service life of silicone in natural environment can reach several decades.
3. Electrical insulation performance
Silicone products have good electrical insulation performance, and their dielectric loss, voltage resistance, arc resistance, corona resistance, volume resistance coefficient and surface resistance coefficient are among the best among insulation materials, and the electrical performance is less affected by temperature and frequency. Therefore, they are a kind of stable electrical insulating materials, which are widely used in electronic and electrical industries. Silicone not only has excellent heat resistance, but also has excellent water repellency, which ensures the high reliability of electrical equipment under wet conditions.
4. Physiological inertia
Polysiloxane compounds are one of the most inactive compounds known. They are very resistant to biological aging, have no rejection with animals, and have good anticoagulant properties.
5. Low surface tension and low surface energy
The main chain of silicone is very flexible, and the intermolecular force is much weaker than that of hydrocarbons. Therefore, compared with hydrocarbons with the same molecular weight, it has lower viscosity, weaker surface tension, smaller surface energy and stronger film-forming ability. This low surface tension and low surface energy are the main reasons for many applications: excellent properties such as hydrophobicity, defoaming, foam stability, anti-sticking, lubrication and glazing.
Second, the use of silica gel
Because of these excellent properties, silicone has a wide range of applications. It is not only used as a special material for aviation, cutting-edge technology and military technology departments, but also used in various departments of the national economy. Its application scope has been extended to: architecture, electronics and electricity, textiles, automobiles, machinery, leather and paper, chemical industry and light industry, metals and coatings, medicine and medical treatment.
Third, the classification of silicone
Silicone is mainly divided into three categories: silicone rubber, silicone resin and silicone oil.
Four, silicone rubber classification
Silicone rubber is mainly divided into room temperature vulcanized silicone rubber and high temperature vulcanized silicone rubber.
Brief introduction and classification of room temperature vulcanized silicone rubber
Room temperature vulcanized silicone rubber (RTV) is a new type of silicone elastomer that came out in 1960s. The most remarkable feature of this rubber is that it can be cured in situ at room temperature without heating or pressure, and it is very convenient to use. So it became an important part of silicone products as soon as it came out. At present, room temperature vulcanized silicone rubber has been widely used as adhesives, sealants, protective coatings, potting and molding materials, and has its uses in all walks of life.
Room temperature vulcanized silicone rubber can be divided into one-component and two-component room temperature vulcanized silicone rubber according to its packaging mode, and can be divided into condensation type and addition type according to vulcanization mechanism. Therefore, RTV silicone rubber can be divided into three types according to composition, vulcanization mechanism and application process, namely, one-component RTV silicone rubber, two-component condensed RTV silicone rubber and two-component addition RTV silicone rubber. These three series of room temperature vulcanized silicone rubber have their own characteristics: one-component room temperature vulcanized silicone rubber has the advantage of convenient use, but the deep vulcanization speed is difficult; Two-component RTV silicone rubber has the advantages of no heat release, small shrinkage, no expansion and no internal stress during curing, and can be cured at the same time on the inner surface and deeply vulcanized; The curing time of addition room temperature vulcanized silicone rubber mainly depends on the temperature, so the curing speed can be controlled by adjusting the temperature.
Among many synthetic rubbers, silicone rubber is the best. It is odorless and nontoxic, and is not afraid of high temperature and cold. It is "poised" and "face neutral" at 300 degrees Celsius and 90 degrees below zero, and still maintains its original strength and elasticity. Silicone rubber also has good electrical insulation, oxygen resistance and aging resistance, light resistance and aging resistance, mildew resistance and chemical stability. Because of these excellent properties, silicone rubber has been widely used in modern medicine. In recent years, hospitals, scientific research units and factories have successfully trial-produced a variety of silicone rubber medical supplies.
Silicone rubber anti-noise earplugs: comfortable to wear, can block noise well and protect the eardrum.
Silicone rubber fetal head aspirator: easy to operate, safe to use, can be deformed according to the size of fetal head, and the fetal scalp will not be sucked up during aspiration, which can avoid scalp hematoma and intracranial injury and greatly alleviate the pain of dystocia pregnant women during delivery.
Silicone rubber artificial blood vessel: It has special physiological function and can be in close contact with the human body, which is not rejected by the human body. After a certain period of time, it will be completely stable with human tissues.
Silicone rubber eardrum repair subsidy: thin and soft, good smoothness and toughness. It is an ideal material for repairing eardrum, with simple operation and quite good effect.
In addition, there are silicone rubber artificial trachea, artificial lung, artificial bone and silicone rubber duodenum tube. And their effect is very ideal.
Application of room temperature vulcanized silicone rubber
With the progress and development of modern science and technology, the application of silicone rubber in medicine will have a broader prospect.
Foamed silicone rubber is based on condensed hydroxyl-terminated silicone rubber, with hydroxyl-containing silicone oil as foaming agent and vinyl platinum complex as catalyst (heating).
T-type catalyst is dibutyltin dilaurate), which is a sponge-like elastomer. It is foamed and vulcanized at room temperature to form holes. In order to improve the quality of foam, some other components, such as silicone oil, should be added to make the vulcanization process produce more gas. Improve hand feeling and reduce foam density. The addition of diphenyl silicone glycol can not only control the foam structure, but also control the viscosity increase of the rubber compound during storage, but the dosage should not be too much, otherwise it will affect the electrical properties of the foam. In order to improve the physical and mechanical properties of the foam, transparent silicone rubber can also be added. The amount of vinyl complex of chloroplatinic acid as catalyst should not be too much, which is based on convenient operation, otherwise the viscosity will increase, which is not conducive to operation; When the amount of catalyst is insufficient, the vulcanization is incomplete, the foam surface is sticky, the elasticity is not good, it is soft and plastic, and the strength is poor.
Foamed silicone rubber is liquid before vulcanization and is suitable for potting. The vulcanized foam can be used at -60~ 159℃ for a long time, and the foam still maintains its original properties after being used at 150℃ for 72 hours or at -60 ~ 170℃ for ten times alternately.
Foamed silicone rubber has high thermal stability, good heat insulation, moisture resistance and impact resistance, especially at high frequency, and is an ideal lightweight packaging material. Used for all kinds of electronic components, instruments, meters, instrument wheels of flying bodies, etc. , can play the role of "three defenses" protection against moisture, earthquake and corrosion. In addition, it can also be used as a filling material for thermal insulation interlayer, a floating material in salt fog environment and a sealing material. Foamed silicone rubber can also be used as filling, repairing and prosthetic materials in plastic surgery.
In order to meet the fire protection requirements of transmission lines, Corning Company of the United States developed flame retardant room temperature vulcanized foamed silicone rubber DC3-6548. This kind of foam silicone rubber is mainly used for fireproof sealing where wires and cables pass (such as roofs, walls, holes in buildings, etc.). ), and its flame retardant performance is very good. Its limiting oxygen index reaches 39 (the limiting oxygen index of most plastics is only 20) and its service life is as long as 50 years. At present, this kind of flame retardant room temperature vulcanized foamed silicone rubber has been widely used in places with harsh environmental conditions or particularly high fire protection requirements, such as nuclear power plants, computer centers, offshore oil production devices and so on.
Brief introduction of two-component condensed RTV silicone rubber 2007-05-24 09:09 Two-component condensed RTV silicone rubber is the most common RTV silicone rubber. Its raw rubber is usually hydroxyl-terminated polysiloxane, which combines with other complexing agents and catalysts to form a compound. The viscosity of this compound ranges from 100 CST to one million CST.
The vulcanization reaction of two-component room temperature vulcanized silicone rubber is not initiated by moisture in the air, but by catalyst. Silicone rubber, filler and crosslinking agent are usually packaged as one component, and the catalyst is packaged as another component separately, or other combination methods are adopted, but the catalyst and crosslinking agent must be packaged separately. No matter what packaging method is adopted, curing only begins when the two components are completely mixed together. The commonly used crosslinking agent is ethyl orthosilicate, and the catalyst is dibutyltin dilaurate. And suitable fillers and additives are added according to the properties of the required final product. In recent years, dibutyltin dilaurate is a moderately toxic substance, which has been banned from being used in food bags and plasma bags in many countries, and has been basically replaced by octyl tin with lower toxicity.
The curing time of two-component condensation room temperature vulcanized silicone rubber mainly depends on the type, dosage and temperature of catalyst. The more catalyst is used, the faster vulcanization and the shorter shelf life. At room temperature, storage time is usually several hours. If you want to prolong the storage time of the rubber mixture, you can use the cooling method. It takes about one day for the two-component condensation type room temperature silicon sulfide rafter to be completely cured at room temperature, but it only takes 1 hour at 150℃. Synergistic effect can significantly improve the curing speed of γ -aminopropyl triethoxysilane.
Two-component room temperature vulcanized silicone rubber can keep elasticity for a long time in the temperature range of 65 ~ 250℃, and has excellent electrical properties and chemical stability, water resistance, ozone resistance and weather resistance. In addition, it is simple to use and has strong process applicability, so it is widely used as potting and molding materials. After all kinds of electronic and electrical components are coated and packaged with room temperature vulcanized silicone rubber, the purpose of moisture-proof (anti-corrosion, shock-proof) can be achieved. Performance and stable parameters can be improved. Two-component RTV silicone rubber is especially suitable for deep potting materials, and its curing time is faster than that of single-component RTV silicone rubber.
One-component room temperature vulcanized silicone rubber
The vulcanization reaction of one-component room temperature vulcanized silicone rubber is to react with moisture in the air and vulcanize into elastomer. Using different chain agents, one-component RTV silicone rubber can be deacidified, deoximated, dealcoholized, deaminated, deamidated and ketonized. The curing time of one-component room temperature vulcanized silicone rubber depends on curing system, temperature, humidity and the thickness of silicone rubber layer. Increasing the temperature and humidity of the environment can accelerate the curing process. Under typical environmental conditions, after 15~30 minutes, the surface of silicone rubber will not stick, and the 0.3 cm thick adhesive layer can be cured within one day. The curing depth and strength will gradually increase in about three weeks.
One-component RTV silicone rubber has excellent electrical properties and chemical inertness, as well as heat resistance, natural aging resistance, flame retardancy, moisture resistance and air permeability. They can keep elasticity for a long time in the range of -60~200℃. It does not absorb heat or release heat during curing, and has small shrinkage after curing and good adhesion to materials. Therefore, it is mainly used as adhesive and sealant, and other applications include in-situ forming gasket, protective coating and caulking material. Many formulations of one-component silicone rubber adhesive show self-adhesion to various materials such as most metals, glasses, ceramics and coagulants. When bonding is difficult, primer can be applied to the substrate to improve the bonding strength. Primers can be reactive silane monomers or resins, and when they are cured on the substrate, a modified surface suitable for siloxane bonding is produced. One-component RTV silicone rubber is easy to use, but its vulcanization depends on the moisture in inert atmosphere, which limits the thickness of vulcanized rubber, and can only be used when the thickness is less than 6 mm The vulcanization reaction of one-component RTV silicone rubber is carried out gradually from the surface to the depth, and the thicker the adhesive layer, the slower the curing. When the deep part needs rapid vulcanization, the method of layered pouring and gradual vulcanization can be adopted, and some mixed rubber can be added each time, and then the material can be replenished after vulcanization, so that the total vulcanization time can be reduced. Adding magnesium oxide can accelerate the vulcanization of deep glue.
2. Two-component condensation room temperature vulcanized silicone rubber
The vulcanization reaction of two-component room temperature vulcanized silicone rubber is not initiated by moisture in the air, but by catalyst. Usually, the rubber compound and the catalyst are packaged as one component. Curing begins only when the two components are completely mixed together. The curing time of two-component condensation room temperature vulcanized silicone rubber mainly depends on the type, dosage and temperature of catalyst. The more catalyst is used, the faster vulcanization and the shorter shelf life. At room temperature, storage time is usually several hours. If you want to prolong the storage time of the rubber mixture, you can use the cooling method. It takes about one day for the two-component condensation type room temperature silicon sulfide rafter to be completely cured at room temperature, but it only takes 1 hour at 150℃. The curing speed can be significantly improved by using the synergistic effect of accelerators.
Two-component room temperature vulcanized silicone rubber can keep elasticity for a long time in the temperature range of 65~250℃, and has excellent electrical properties and chemical stability, water resistance, ozone resistance and weather resistance. In addition, it is simple to use and has strong process applicability, so it is widely used as potting and molding materials. After all kinds of electronic and electrical components are coated and packaged with room temperature vulcanized silicone rubber, the purpose of moisture-proof (anti-corrosion, shock-proof) can be achieved. Performance and stable parameters can be improved. Two-component RTV silicone rubber is especially suitable for deep potting materials, and its curing time is faster than that of single-component RTV silicone rubber. Two-component room temperature vulcanized silicone rubber has excellent anti-sticking performance after vulcanization, and the shrinkage rate during vulcanization is extremely small, so it is suitable for making soft molds and molds of epoxy resin, polyester resin, polystyrene, polyurethane, vinyl plastic, paraffin wax, low melting point alloy and so on. In addition, using the high simulation performance of two-component room temperature vulcanized silicone rubber, various exquisite patterns can be reproduced on cultural relics. When using two-component room temperature vulcanized silicone rubber, attention should be paid to: firstly, weigh rubber and catalyst respectively, and then mix them in proportion. The mixing process should be carefully operated to minimize the amount of entrained gas. After the rubber is evenly mixed (uniform color), bubbles can be removed by standing or depressurizing (vacuum degree is 700 mm Hg). After all the bubbles are discharged, it can be vulcanized at room temperature or specified temperature for a certain period of time to vulcanize it into silicone rubber.
3. Two-component addition molding room temperature vulcanized silicone rubber
Two-component addition room temperature vulcanized silicone rubber can be divided into elastic silicone rubber and silicone rubber, the former has lower strength and the latter has higher strength. Their vulcanization mechanism is based on the addition reaction (hydrosilylation reaction) between the vinyl group (or propylene group) on the end group of raw silicone rubber and the hydrosilylation group on the cross-linking agent molecule. In this reaction, no by-products are released. Because low molecular weight substances are not released during crosslinking, the addition room temperature vulcanized silicone rubber does not shrink during vulcanization. This vulcanized rubber has the advantages of non-toxicity, high mechanical strength, excellent hydrolysis resistance (even under high pressure steam), good low compression deformation, low flammability, deep vulcanization, controllable temperature and so on. It is a kind of silicone rubber developed vigorously at home and abroad. Two-component room temperature vulcanized silicone rubber can keep elasticity for a long time in the temperature range of 65 ~ 250℃, and has excellent electrical properties and chemical stability, water resistance, ozone resistance and weather resistance. In addition, it is simple to use and has strong process applicability, so it is widely used as potting and molding materials. After all kinds of electronic and electrical components are coated and packaged with room temperature vulcanized silicone rubber, the purpose of moisture-proof (anti-corrosion, shock-proof) can be achieved. Performance and stable parameters can be improved. Two-component RTV silicone rubber is especially suitable for deep potting materials, and its curing time is faster than that of single-component RTV silicone rubber.
Two-component room temperature vulcanized silicone rubber has excellent anti-sticking performance after vulcanization, and the shrinkage rate during vulcanization is extremely small, so it is suitable for making soft molds and molds of epoxy resin, polyester resin, polystyrene, polyurethane, vinyl plastic, paraffin wax, low melting point alloy and so on. In addition, various exquisite patterns can be reproduced by using the high simulation performance of two-component room temperature vulcanized silicone rubber. For example, in the reproduction of cultural relics, it can be used to copy ancient bronzes, and in the production of artificial leather, it can be used to copy the dermatoglyphics of snakes, pythons, crocodiles, pangolins and other animals, which has the effect of confusing the real with the fake.
Several specific problems should be paid attention to when using two-component room temperature vulcanized silicone rubber: first, weigh the base material, crosslinking agent and catalyst respectively, and then mix them in proportion. Generally, the two components should be provided in different colors, so that the mixing of the two components can be observed intuitively, and the mixing process should be carefully operated to minimize the amount of entrained gas. After the rubber is mixed evenly (with uniform color), bubbles can be removed by standing or depressurizing (vacuum degree is 700 mm Hg). After all the bubbles are discharged, they can be vulcanized at room temperature or specified temperature for a certain period of time and then vulcanized into silicone rubber.
The side groups on the main chain of two-component RTV silicone rubber can be replaced by other groups besides methyl, such as phenyl, trifluoropropyl and cyanoethyl. To improve its low temperature resistance, heat resistance, radiation resistance or solvent resistance. At the same time, additives with heat resistance, flame retardancy, thermal conductivity and electrical conductivity can be added as needed to prepare silicone rubber with ablation resistance, flame retardancy, thermal conductivity and electrical conductivity.
(I) Methyl room temperature vulcanized silicone rubber
Methyl room temperature vulcanized silicone rubber is an old variety of general silicone rubber, which has the advantages of water resistance, ozone resistance, arc resistance, corona resistance and weather aging resistance. It can be used in the temperature range of 60 ~ 200℃. Therefore, it is widely used as a potting material for electronic and electrical components, and a moistureproof, shockproof and high and low temperature resistant potting material for instruments and meters. It can also be used to make molds and cast polyester resin, epoxy resin and low melting point alloy parts. It can also be used as a dental impression material. Coating methyl room temperature vulcanized silicone rubber on cotton cloth and paper bags can be made into conveyor belts and packaging bags for conveying sticky articles.
(II) Methyl diphenyl room temperature vulcanized silicone rubber
Methyl diphenyl RTV silicone rubber not only has excellent properties of methyl RTV silicone rubber, but also has a wider service temperature range (-100 ~ 250℃) than methyl RTV silicone rubber. Low-phenyl room-temperature vulcanized silicone rubber (108- 1) with 2.5-5% phenyl can keep elasticity at the low temperature of-120℃, and it is the best variety of silicone rubber at present. Room temperature adhesive (108-2) with phenyl content of 10 ~ 20% has good radiation resistance, ablation resistance and self-extinguishing. 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 use at a high temperature above 250℃ or as an ablative putty coating and packaging material.
Methyl phenyl room temperature adhesive, like other room temperature adhesives, can be used for impregnation, stamping and demoulding. If the adhesion with other materials is to be increased, the surface of the adhered material must be treated before use. The steps of surface treatment are as follows: clean the surface of the material with acetone solvent for 65,438+0 ~ 2 times, then treat it with surfactant for 65,438+0 ~ 2 times, and bake it in an oven at 60℃ for several minutes. At this time, a film with less sticky hands can be formed on the surface of the material, and then glued.
(3) methyl block room temperature vulcanized silicone rubber
Methyl block RTV silicone rubber is a modified variety of methyl RTV silicone rubber, which is a polymer of hydroxyl-terminated polydimethylsiloxane (107 glue) and methyltriethoxysilane oligomer (molecular weight 3 ~ 5). Under the catalysis of dibutyltin dilaurate, hydroxyl groups in polydimethylsiloxane and ethoxy groups in polymethyltriethoxysilane condense to form polymers with three-dimensional structure. The vulcanized elastomer has higher mechanical strength and adhesion than methyl room temperature vulcanized silicone rubber, and can be used for a long time in the temperature range of 70 ~ 200℃.
Methyl block RTV silicone rubber is shockproof, moisture-proof, waterproof, breathable, ozone-resistant, weather-resistant, weak acid and alkali-resistant. It has good electrical insulation, good adhesion and low cost. Therefore, it can be widely used in potting, coating, stamping, demoulding, drug carrier release and other occasions. Electronic components encapsulated by methyl block room temperature adhesive have the functions of shock resistance, moisture resistance, sealing, insulation and stable parameters. If the methyl block room temperature adhesive is directly coated on the loudspeaker, the intermediate frequency point of the loudspeaker can be reduced and eliminated, and the resonance frequency performance of the loudspeaker after vulcanization can be reduced by about 20 Hz. After adding a certain amount of additives, methyl block room temperature adhesive can be used as paper release agent. After coating a thin layer of methyl block room temperature adhesive on candy and biscuit conveyor belts in food industry, the anti-sticking performance of canvas can be improved, thus improving the appearance of food and improving the utilization rate of raw materials.
Adding a proper amount of fumed silica into methyl block room temperature adhesive can be used to install the joints of window glass, curtain wall, window frame, prefabricated board and expansion joint of airport runway. In addition, it can also be used as an adhesive for magnetic cores and templates in electronic computer memories, as well as for conductive silicone rubber and non-conductive silicone rubber. Treating fabrics with methyl block room temperature vulcanized silicone rubber can improve the handle, softness and bending wear resistance of fabrics.
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