Conductive rubber sheet is a kind of rubber plate with special functions, which is mostly processed from rubber with greater polarity as the main raw material, such as nitrile rubber, neoprene rubber, etc., which has the characteristics of good conductivity, high strength, wear resistance and heat resistance. Nitrile rubber, neoprene and other original rubber prices are high, tire tread rubber reclaimed rubber is a waste tire tread part of the crushing, desulfurization, refining and other processes to complete, the price is much lower than nitrile rubber; The use of tread reclaimed rubber instead of part of nitrile rubber to produce conductive rubber can effectively reduce the cost of raw materials on the premise of ensuring the quality of rubber sheets.
1. Nitrile rubber/tread reclaimed rubber is used to produce conductive rubber plate vulcanization formula
50 parts of nitrile rubber, 50 parts of tire tread reclaimed rubber, 3 parts of zinc oxide, 1 part of stearic acid, 1 part of antioxidant D, 30 parts of acetylene carbon black, 15 parts of calcium carbonate, 15 parts of clay, 10 parts of superreinforcing agent SR, 12 parts of dibutyl phthalate, 0.7 parts of accelerator DM, 0.4 parts of accelerator CZ, 1 part of sulfur; Total 189.1 copies.
2. Tire reclaimed rubber and nitrile rubber selection skills for conductive rubber sheets
Conductive rubber sheet requires good electrical conductivity, good mechanical strength and wear resistance. The cyano group contained in the molecular chain structure of nitrile rubber is a strong polar group, and the higher the acrylonitrile content, the lower the resistance value, and the better the conductivity in the production of conductive rubber sheets. Compared with the whole tire reclaimed rubber, the effective rubber hydrocarbon E4LYY1220 content is high, the strength is high, the elasticity is good, the wear resistance and tear resistance are high, and the nitrile rubber is used together to produce conductive rubber sheets, which can provide higher mechanical strength for the conductive rubber sheets.
Nitrile rubber and tire tread reclaimed rubber can be used in any proportion to produce conductive rubber sheets, and when the ratio of the two is 1:1, the comprehensive performance of conductive rubber sheets is better; When the conductive rubber sheet has strict requirements for mechanical properties, the proportion of reclaimed rubber can be appropriately reduced; A high proportion of reclaimed tread rubber is used in combination with a small amount of nitrile rubber to produce conductive rubber sheets with low mechanical property requirements.
3. Nitrile rubber/tread reclaimed rubber combined with the production of conductive rubber sheet formula design points
(1) Vulcanization system
When nitrile rubber/tread reclaimed rubber is used to produce conductive rubber sheets, the sulfur-accelerator system is adopted, with the accelerator DM as the main accelerator and the accelerator CZ as the auxiliary accelerator, the vulcanization speed is faster, and the rubber compound has good conductivity and high hardness, elongation, permanent deformation and tear strength.
(2) Reinforcement filling system
Reinforcing agents and fillers have a great influence on the conductivity of nitrile rubber/tread reclaimed rubber. Conductive rubber sheet formulations use high-structure carbon black, such as acetylene carbon black, conductive carbon black; The larger the amount of acetylene carbon black, the better the conductivity of vulcanized adhesive; The appropriate use of metal powder can further improve the conductivity of the rubber compound. When preparing conductive rubber for tire tread rubber reclaimed rubber, clay and calcium carbonate are commonly used as fillers, but too much clay will destroy the conductive properties of the conductive rubber sheet.
(3) Softening plasticizing system
When nitrile rubber/tread reclaimed rubber is used together to produce conductive rubber sheets, it is recommended to use dibutyl phthalate, which has good compatibility with nitrile rubber, especially when the proportion of nitrile rubber is high, it is not easy to exud the surface of the rubber sheet. Petroleum-based softeners such as engine oil, paraffin, petroleum jelly, etc. have strong mutual permeability with nitrile rubber, and the surface of semi-finished rubber and vulcanized finished products is easy to seep out to form a layer of film, which affects the electrical properties of conductive rubber sheets and is not suitable for use.
4. Nitrile rubber/tread reclaimed rubber is used together to produce conductive rubber sheets
When nitrile rubber and tread reclaimed rubber are used in the right proportion to produce conductive rubber sheets, the production process parameters need to be strictly controlled.
(1) Mixing: It is recommended to operate at a lower temperature, 55±5°C for the front roller and 50±5°C for the rear roller, so that the conductive particles, non-conductive particles and rubber are evenly mixed; If the temperature is too high at the beginning of mixing, the conductive particles will be tightly bound to the rubber before they are fully mixed with other non-conductive particles, which will affect the conductive effect.
(2) Vulcanization: In the vulcanization process of nitrile rubber/tread reclaimed rubber combined with rubber compound, it is recommended to use higher temperature vulcanization, and the vulcanization conditions are controlled at 145 °C and 10min. The size of the chain is proportional to the diffusion degree of conductive particles such as carbon black, and the momentum of the generated chain is larger than the momentum of a single particle, so the resistivity of the rubber decreases with the increase of vulcanization temperature, and the conductivity of vulcanized rubber improves.
Conductive rubber sheets are widely used in electronic appliances, industrial manufacturing, automobiles, medical equipment, aerospace and other fields. When using nitrile rubber/tread reclaimed rubber to produce conductive rubber sheets, select appropriate tire reclaimed rubber according to the specific application and performance requirements of conductive rubber sheets, reasonably determine the ratio of nitrile rubber and tread reclaimed rubber, and appropriately adjust the formula and production process parameters to meet the diverse needs of different industries for conductive rubber sheets.
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