Hard rubber is a vulcanized rubber with more sulfur content, which is a black and hard substance at room temperature, almost inelastic, with good electrical insulation and chemical stability, and is widely used in the production of electrical insulation products, rubber linings and other products. Tire reclaimed rubber has the basic performance characteristics of rubber, low price, good elasticity, can be used alone or with natural rubber, synthetic rubber to prepare hard rubber, effectively reduce the cost of raw materials.
1. The advantages of using tire reclaimed rubber for hard rubber
The use of tire reclaimed rubber in the preparation of hard rubber can not only reduce the cost of raw materials, but also improve the process performance of rubber compound and the performance of finished products, which is manifested in the following points:
(1) The rubber mixed with reclaimed rubber has good fluidity, small shrinkage of the rubber material, which is convenient for calendering and extrusion operations, and has few appearance defects of semi-finished products; (2) The heat generation of mixing, hot mixing, extrusion, calendering and other materials is lower than that of pure raw rubber compounds, which is very important for rubber compounds with high carbon black content, which can avoid scorching due to high rubber temperature; (3) The thermoplasticity of the rubber mixed with reclaimed rubber is small, which reduces the deformation of the product during direct steam vulcanization; (4) The heat generation is reduced, and the heat generation of mixing, hot mixing, extrusion, and calendering is lower than that of pure raw rubber compounds, which can avoid scorching due to high rubber temperature.
2. Key points of the formula design of hard rubber mixed with tire reclaimed rubber
(1) Vulcanization system: when tire reclaimed rubber alone or tire reclaimed rubber is used in combination with natural rubber and styrene-butadiene rubber to produce hard rubber, sulfur is generally used as a vulcanizing agent, and the dosage is among 20% and 50%; For hard rubber with high electrical insulation requirements, sulfur-free sulfur is recommended. Use medium and slow accelerators such as quacs and aldehydes and amines, or calcium oxide and magnesium oxide combined with sulfur to improve vulcanization efficiency and shorten vulcanization time.
The combination of sulfur and selenium can promote vulcanization while improving the heat resistance and electrical insulation of tire reclaimed rubber and hard rubber products.
(2) Filling system: hard rubber is generally filled with a large number of fillers to save raw rubber and reduce costs, commonly used fillers are hard rubber powder, white powder, clay, talc, barite powder, silica, diatomaceous earth, etc. When using tire reclaimed rubber to prepare acid-resistant hard rubber, clay, white lean powder, barite powder, silica and diatomaceous earth can be used; When hard rubber requires light resistance and heat resistance, it is recommended to fill it with calcium carbonate.
(3) Softening system: the rational use of softener in the preparation of tire reclaimed rubber hard rubber can improve the process performance of rubber mixing, calendering, extrusion, etc., and increase the viscosity E4LYY314 rubber material; Commonly used softeners are mineral oil, petroleum jelly, bitumen, paraffin, coumaron resin, dry oil or ointment. Hard rubber uses asphalt and coumaron resin as softeners to increase the viscosity of tire reclaimed rubber; The reclaimed rubber hard rubber using paraffin wax and petroleum jelly has little deformation; Paraffin, rapeseed oil, and linseed oil can give hard rubber a better gloss.
Stiffeners and antioxidants are generally not used in hard rubber formulations. When using tire reclaimed rubber to prepare hard rubber, a reasonable design formula can further optimize the quality of the finished product and the production process, and reduce more costs. Follow-up to share with you the preparation of tire reclaimed rubber, hard rubber vulcanization formula and processing points.
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