Sponge rubber washers made primarily from natural rubber have good elasticity, softness, flex resistance, and heat insulation properties, and are widely used in automobiles, construction, and machinery equipment. From a cost perspective, natural rubber is expensive and its price fluctuates significantly, making cost control difficult. Therefore, it is essential to use low-cost and stable reclaimed rubber as a substitute for natural rubber. So, which types of reclaimed rubber can replace natural rubber in the production of sponge washers? How much reclaimed rubber is appropriate to add? How should a formula for sponge rubber washers containing reclaimed rubber be designed?
1. Which reclaimed rubbers can be blended into natural rubber sponge washers?
(1) Latex reclaimed rubber
Reclaimed latex rubber is processed from waste natural rubber, waste latex, and their products. It has characteristics such as high effective rubber hydrocarbon content, good elasticity, low density, and high tensile strength. It is an ideal material to replace natural rubber in the production of sponge rubber gaskets. For black natural rubber sponge gaskets, it is recommended to use black reclaimed latex rubber, which is more cost-effective; for white or colored rubber gaskets, white reclaimed natural latex is recommended, as it is lighter in color and easier to match.
(2) Tire reclaimed rubber
Tire reclaimed rubber is processed from waste tire rubber powder as raw material. It possesses the basic performance characteristics of rubber, with its main components being natural rubber, general synthetic rubber, and carbon black. It is highly compatible with natural rubber and can be used alone or together with natural rubber to produce black sponge rubber gaskets, reducing more raw material costs and saving labor and electricity.
2. Key points in the formulation design of natural rubber sponge gaskets containing reclaimed rubber
When using recycled rubber to reduce the cost of natural rubber sponge gaskets, the rubber compound must have sufficient mechanical strength, good elasticity, low permanent deformation, as well as resistance to compression set and aging. When designing the formula for recycled rubber sponge gaskets, the vulcanization system must match the foaming system to ensure uniform foaming of the rubber compound.
3. Vulcanization formula for natural rubber sponge gaskets containing recycled rubber
(1) Formula for producing black sponge gaskets using a combination of natural rubber and tire recycled rubber
Natural rubber 75 parts, tire reclaimed rubber 25 parts, zinc oxide 4 parts, stearic acid 3 parts, antioxidant 4010 1 part, antioxidant RD 1 part, paraffin 1 part, carbon black N774 15 parts, light calcium carbonate 90 parts, motor oil 15 parts, accelerator CZ 0.8 part, sulfur 1 part, foaming agent H 2.3 parts, sodium bicarbonate 3.8 parts; total 237.9 parts.
(2) Formula for producing colored sponge washers using both natural rubber and latex reclaimed rubber
Natural rubber 50 parts, white natural latex reclaimed rubber 50 parts, zinc oxide 4 parts, stearic acid 3 parts, antioxidant RD 3 parts, paraffin 2 parts, light calcium carbonate 60 parts, accelerator CZ 1.6 parts, accelerator TMTD 0.1 part, sulfur 0.8 part, foaming agent H 4 parts, coloring agent 1 part.
(3) Vulcanization formula for producing black sponge washers using all latex reclaimed rubber
Black natural latex reclaimed rubber 100 parts, zinc oxide 2 parts, stearic acid 6 parts, antioxidant D 2 parts, paraffin 3 parts, spray carbon black 35 parts, vaseline 15 parts, asphalt 5 parts, accelerator DM 1 part, sulfur 2.6 parts, foaming agent H 4 parts, urea 1 part, water 5 parts; total 181.6 parts.
Ultra-fine filtered black latex reclaimed rubber, made from imported mixed-color waste latex gloves, is characterized by high fineness, no impurities, odorless, good elasticity, and high elongation at break. When producing rubber product E5LYY612, it does not require mastication, and by replacing natural rubber at a ratio of 1.3:1, it can significantly improve the product's tear resistance, aging resistance, and flex durability. In actual production, which other types of reclaimed rubber can also partially replace natural rubber for producing sponge washers? We will continue to discuss related issues later.
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