Natural rubber has high mechanical strength and good elasticity, but the heat resistance is average, so when using natural rubber to produce heat-resistant rubber sealants, it is mostly used in combination with styrene-butadiene rubber, neoprene and recycled rubber to improve the heat resistance and aging resistance of the rubber. As a product of waste rubber recycling, reclaimed rubber has good performance and low price, and the production of general heat-resistant sealant can effectively reduce the cost of raw materials under the premise of ensuring the performance of rubber compounds.
1. Natural rubber/reclaimed rubber is used together to produce a general heat-resistant rubber vulcanization formula
(1) 75 parts of natural rubber, 25 parts of recycled rubber, 19 parts of zinc oxide, 0.8 parts of stearic acid, 2 parts of antioxidant D, 35 parts of carbon black N774, 30 parts of clay, 15 parts of mica powder, 4 parts of heavy oil, 2.3 parts of accelerator TMTD, 0.4 parts of sulfur, total: 208.5 parts.
(2) 75 parts of natural rubber, 25 parts of recycled rubber, 15 parts of zinc oxide, 1.2 parts of stearic acid, 1 part of antioxidant D, 23 parts of carbon black N774, 30 parts of clay, 7.5 parts of mica powder, 4 parts of heavy oil, 2.3 parts of accelerator TMTD, 0.4 parts of sulfur; Total: 184.4 parts.
2. Natural rubber/reclaimed rubber is used to produce a general heat-resistant rubber formula design
Rubber sealing products require the rubber compound to have sufficient mechanical strength, good elasticity and low permanent deformation, and the general heat-resistant sealant also requires certain high temperature resistance and aging resistance. When natural rubber/reclaimed rubber is used together to prepare general heat-resistant sealant compounds, reasonable design of vulcanization system and reinforcing filling system can further improve the heat aging resistance of vulcanized rubber compounds.
(1) Vulcanization system
In the vulcanized rubber structure formed by the low-sulfur yellow vulcanization system, the monosulfide bond and the disulfide bond are dominant, and this cross-linked structure makes the natural rubber/reclaimed rubber vulcanized rubber have high heat resistance, reduce the compression and permanent set of the rubber, and meet the basic performance requirements of general sealing rubber products. In the low-sulfur vulcanization system, appropriately increasing the amount of zinc oxide can reduce the amount of sulfur to a certain extent, activate the vulcanization system, improve the vulcanization efficiency, and improve the aging resistance of vulcanized rubber.
(2) Reinforcement filling system
Carbon black N774 is a high-tensimile semi-reinforcing furnace black, which has good dispersion and reinforcing properties, which can improve the hardness, strength and wear resistance of rubber, as well as the weather resistance E4LYY424 and oxidation resistance of rubber. Inorganic fillers are more heat-resistant than carbon black compared to carbon black. The reinforcing performance of clay is lower than that of silica and higher than that of calcium carbonate, which is easy to disperse in rubber and has a large amount of use, which can improve the process performance of rubber compounds; Increase the density and density of rubber, and improve the heat resistance and chemical resistance of rubber products.
When natural rubber/reclaimed rubber is used to prepare heat-resistant sealant compounds, a reasonable design of vulcanization system and reinforcing filling system can improve the heat resistance and aging resistance of vulcanized rubber while meeting the basic mechanical properties and elastic requirements. In addition, in actual production, choosing the right antioxidant and softener can also improve the heat resistance of natural rubber/reclaimed rubber to a certain extent, meet the physical property needs of more heat-resistant sealing rubber products, expand the scope of use, and improve economic benefits.
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