The most commonly used reinforcing agents when using latex recycled rubber or natural rubber/latex recycled rubber combined with rubber to produce rubber products are carbon black and silica, and the varieties and dosages of reinforcing agents used in natural recycled rubber products in different usage occasions and different colors are very different. So how to correctly choose carbon black and silica in the production of natural latex recycled rubber products?
1. Classification and performance characteristics of carbon black
Rubber carbon black is a form of carbon element, which is mainly used to reinforce rubber, which can significantly improve the wear resistance, tensile strength and tear strength of natural latex recycled rubber products. Carbon black can be divided into E5LYY411 hard carbon black and soft carbon black according to reinforcing properties; According to the use performance, it can be divided into ultra-wear-resistant carbon black, medium-super wear-resistant carbon black, high wear resistant carbon black, fine-grained carbon black, fast-pressed carbon black, general carbon black, high-limit elongation carbon black, semi-reinforced carbon black, hot cracking carbon black, easy-to-mix groove black, etc.
2. Classification and performance characteristics of silica
Silica is a general term for white powdered X-ray amorphous silicic acid and silicate products, which can be divided into precipitation (wet) silica and vapor phase (dry or burning) silica according to the production method. Compared with carbon black, silica has a higher specific surface area and finer particles; After the natural latex recycled rubber is reinforced with silica, the tensile strength, tear strength and wear resistance of vulcanized rubber are high, but the elasticity decreases.
3. Selection skills of carbon black and silica in the production of natural latex recycled rubber products
(1) When using latex recycled rubber to produce black and dark rubber products, carbon black is usually the main product; If it is a white, light, or colored product, silica can be used instead of carbon black. When choosing carbon black, pay attention to the particle size, structure, surface activity and pH value of carbon black; Compared with gas-phase silica, precipitation silica has low price and good processability, and is more suitable for the production of ordinary light-colored latex recycled rubber products.
(2) When using silica for reinforcement of light-colored and colored rubber products produced by natural latex recycled rubber, it is recommended to use organic activators diethylene glycol (DEG), glycerin, triethanolamine (TEA), polyethylene glycol (PEG), etc. (5%-10% of the amount of silica) to adjust the vulcanization rate.
(3) When latex recycled rubber and natural rubber/latex recycled rubber are used to produce rubber products that require high wear resistance, high tensile strength and high tear resistance, high wear resistance carbon black, medium and super wear resistance carbon black, etc., with small particle size and large specific surface area, can form a strong chemical bond with rubber molecules and significantly improve the mechanical properties of the rubber material.
(4) When using latex recycled rubber to produce rubber products with high tear resistance, the best effect is to use trough carbon black or modified furnace carbon black.
(5) Natural latex recycled rubber products do not have high requirements for strength, but when the elasticity and processing performance are good, they can be used for fast pressing furnace black, general furnace black, semi-reinforced furnace black, etc.
(6) pH value affects the vulcanization efficiency of latex recycled glue, and the latex recycled rubber material using furnace carbon vinyl material should be combined with aftereffect accelerators (CZ, NOBS, etc.), and the dosage should not be too large.
(7) The ozone resistance and aging resistance of silica is better than that of carbon black, which can improve the service life of latex recycled rubber products to a certain extent.
(8) When using latex recycled rubber to produce extruded calendered products, it is required to be easy to disperse, low heat generation, and high fluidity, and it is recommended to use silica, fast-pressing furnace black or general-purpose furnace black.
There are still many things to pay attention to when choosing carbon black or silica as a reinforcing agent for natural latex recycled rubber products, and we will continue to discuss related issues with you later.
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