EPDM rubber seals have excellent high and low temperature resistance, ozone resistance, weather resistance, good resilience, electrical insulation, water resistance, etc., and are widely used in automobile, construction, petrochemical, electric power and other industries. EPDM reclaimed rubber is processed from EPDM unvulcanized rubber compound or waste EPDM rubber products as raw materials, which retains the basic performance characteristics of EPDM original rubber, and can be used alone or in combination with EPDM to produce rubber sealing strips, effectively reducing the cost of raw materials.
1. Stability of mechanical properties of EPDM reclaimed rubber
Compared with EPDM reclaimed rubber, the mechanical properties of EPDM reclaimed rubber are slightly insufficient in terms of elasticity and tensile strength. The raw material source of EPDM reclaimed rubber is complex, and the stability of mechanical properties will be affected by the fluctuation of raw material quality. When using EPDM reclaimed rubber to produce rubber seals, the tensile strength, elongation at break, hardness, Mooney viscosity and other aspects of each batch of reclaimed rubber must be strictly tested to ensure the stability of the mechanical properties of EPDM reclaimed rubber.
2. The proportion of EPDM reclaimed rubber in the rubber sealing ring
EPDM reclaimed rubber has good compatibility with EPDM rubber and can be used in any proportion. Under normal circumstances, the mixing ratio of EPDM reclaimed rubber in the EPDM rubber sealing ring formula is controlled at 30%-50%, and the sealing ring has better performance and lower cost. The performance requirements of rubber seals are different in different applications, and it is recommended to determine the optimal ratio of combined use through experiments.
3. Optimization of the formula of rubber sealing ring for the production of EPDM reclaimed rubber
When using EPDM reclaimed rubber to reduce the production cost of rubber seals, it is necessary to reasonably adjust the formula according to the specific performance requirements of rubber seals. Proper adjustment of the vulcanization system can enhance the sealing performance of the sealing ring and balance the elasticity and hardness of the rubber compound. Reinforcing fillers can not only improve the physical properties of the product, but also improve the processability of EPDM rubber and EPDM reclaimed rubber.
Sulfur vulcanization systems and peroxide vulcanization systems are two common options: sulfur vulcanization systems are lower cost and suitable for products with general performance requirements; The peroxide vulcanization system, on the other hand, has better heat resistance and compression set, and is suitable for high-performance seals. Reinforcing fillers can significantly improve the mechanical properties and wear resistance of the seals. Carbon black is a commonly used reinforcing agent to improve mechanical strength and wear resistance; It can also be used with silica, calcium carbonate, clay, etc.
4. Adjustment of the production process of rubber sealing ring containing EPDM reclaimed rubber
The processing properties of EPDM reclaimed rubber are different from EPDM original rubber, and special attention needs to be paid in the mixing and vulcanization process. The fluidity of reclaimed rubber is good, so it is recommended to fully compound the original rubber and then add reclaimed rubber to ensure the uniformity of the rubber compound. In addition, the vulcanization temperature and time should also be adjusted according to the characteristics of the reclaimed rubber to avoid under-sulfur or over-sulfur. In actual production, the rationality of the processing technology can be verified through small-scale and pilot tests to ensure that the performance of the sealing ring meets the design requirements.
5. EPDM rubber/EPDM reclaimed rubber is used to produce sealing ring vulcanization formula reference
70 parts of EPDM rubber, 30 parts of Hongyun excellent environmental protection EPDM reclaimed rubber, 4.5 parts of zinc oxide, 1 part of antioxidant RD, 45 parts of carbon black N550, 5 parts of paraffin oil, 7 parts of DCP; Total 162.5 copies.
When using EPDM reclaimed rubber to replace part of EPDM rubber in the production of sealing rings, it is necessary to comprehensively consider the quality stability of reclaimed rubber, the proportion of blending, the selection of vulcanization system, the design of reinforcing filling system, and the optimization and adjustment of processing technology, so as to ensure the quality of finished rubber seals and reduce more raw material costs and production energy consumption.
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