Silicone rubber mixing process
Silicone rubber compounding process:
1. Mixing mill mixing
Two-roll mills roll ratio of 1.2 to 1.4: suitable, quick roll in the post, the higher ratio leading to faster mixing, smooth low-speed film than you can. Roller to pass a cooling water, mixing temperature below 40 ℃ appropriate, to prevent scorching or curing agent volatilization. Roll away from the small mixing pm (1 ~ 5mm), and then gradually enlarged. Charging and operation of the order: raw rubber (including roll) - → reinforcing filler - → structure control agents - → heat-resistant additives - → coloring agents - → thin through 5 - → cutting, heat treatment oven - → back to refining - → curing agent - → thin links - → parked overnight - → return refining - → a film. Rubber or not by the oven heat treatment, after joining the heat-resistant additives, curing agent and then adding thin links, parking overnight back to refining, and then parked a few days back to refining the film used. Mixing time of 20 to 40 minutes (mixing mill specifications φ250mm × 620mm). If alone precipitated silica or weak reinforcing filler (titanium dioxide, zinc, etc.), the compound may be no need to include structural control agent. Should be slowly adding filler to prevent the fill material and raw rubber spheroid formed by accumulation of plastic floating in the top of the uneven dispersion result. If you want to join a lot of filler, preferably in two or three times to join, and in the process planning tool to ensure good dispersion. Found to have granule tendency of rubber, can be tightened to improve the mixing roller distance. Splice plate on the falling particles should be clean with a brush and collected, immediately roll back to rubber mixing machine, otherwise the mixing rubber compound containing the knots caused by poor surface appearance. Increment of reinforcing filler filler should be added after completion, can be used from a wide roll. Installed plastic capacity (rubber compound): φ160mm × 320mm mixing machine for 1 ~ 2 kg; φ250mm × 620mm rubber mixing machine for 3 ~ 5kg. Silicone rubber mixing machine joining the slow roll package (front roll), mixing time is quickly package fast roll (after roll), mixing must be able to operate on both sides. As the silicone rubber compound is quite soft and can be common when the assigned sub-mixing tool operation, communication could not be as thin as ordinary rubber sheet pulled down, while the use of steel, nylon or plastic scraper scraped wear. In order to facilitate cleaning and to prevent oil leakage into the gel should be used activity baffle. Fumed silica Gigalight on human health, and should take appropriate measures for labor protection. Such as when used directly in the mixing powdered peroxide, explosion-proof measures must be taken to the best use of cream peroxide. If the compound mixed with impurities, lumps, etc., can be re-pass filter rubber machine rubber compound filter, filtration, generally 80 ~ 140 mesh sieve by mixing mill mixing, which include: 1) package roll: raw rubber bag at the front roller; 2) eat flour process: the need to add the additives according to some logical sequence, accession, accumulation of plastic to pay attention to the volume, less difficult to mix, more will roll is not easy mixing. After the package after eating flour roll. Which generally charge order: raw rubber reinforcing agent → agent → heat → structure control additives; 3) turn refining process: better, faster, more uniform mixing. Knife: a, oblique knife (8 knife) b, triangle bag method; c, hit twisting operation method; d, trace and glue method (take the knife) should also consider the issue, the loaded rubber mixing mill capacity; roller temperature: less than 50 degrees; mixing time: no specific provisions, see operator proficiency. Use kneader, internal mixer with other similar process control, according to kneader capacity, hardness, put some raw rubber. White carbon black. Release agents, brighteners, silicone oil. Mixing the two and a half hours, pulls out the vacuum and a half hours. Can be poured. Cooling, said the weight of a certain proportion to increase curing agent. If purchased directly rubber compound. Curing agent can be added directly 9f
2. Mixer mixing
Using this method can enhance productivity and improve working conditions. Test showed that the performance of sealed rubber compound material and open performance rubber compound material similarity. 2L laboratory mixer with a mixing time of 6 to 16 minutes, mixing no special difficulties. Mixing machine when using φ160mm loading coefficient of 0.74, the mixing can be carried out normally. Discharge temperature and reinforcing filler of the type: When using weak reinforcing fillers and precipitated silica, the latex temperature below 50 ℃; when using fumed silica, the latex temperature about 70 ℃ |
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