Rubber sealing strips are an important part of automobiles, which can improve the sealing, sound insulation, heat insulation, water resistance, etc. of the vehicle, while also helping to improve fuel efficiency. EPDM rubber has excellent heat resistance, weather resistance and ozone resistance, while EPDM reclaimed rubber retains the basic performance characteristics of EPDM rubber. The compounding process is particularly important when using EPDM/reclaimed rubber in combination with rubber for the production of automotive sealing strips.
1. Mixing characteristics of EPDM rubber and EPDM reclaimed rubber
EPDM backbone is known for its saturated structure, which gives it excellent chemical resistance and aging resistance, but it is not easy to wrap rolls during the mixing process, and its roll wrapping performance is mainly achieved by the viscosity of raw rubber Mooney. Compared with EPDM rubber, EPDM reclaimed rubber has good plasticity and fluidity, and has low power consumption during mixing. Therefore, when EPDM rubber/reclaimed rubber is used together, special attention must be paid to the mixing effect of EPDM.
2. EPDM rubber/EPDM reclaimed rubber combined with rubber mixing characteristics
(1) When mixing in the open mill, it is recommended to first use a small roller spacing to make the raw rubber continuously wrap the roller, and then gradually increase the roller spacing and add a compounding agent; Generally, the roller distance should be controlled at 0.2~1 mm, the number of times should be 5~10 times, and the roll temperature should be kept at room temperature. During mixing, the temperature of the front roll is controlled at 40~70°C, and the rear roll is at 50~80°C to optimize the mixing effect. For EPDM rubbers with higher Mooney viscosity or high diene content, the mixing temperature can be appropriately increased and the time can be extended accordingly.
(2) EPDM rubber/EPDM reclaimed rubber combined with rubber is mixed by internal mixer, which can achieve good mixing effect in a short time and at a higher temperature. EPDM rubber has high temperature thermoplasticity, and under the condition of mixing, the complex and oil agent are easier to disperse, and then the complex with good uniformity is obtained.
When EPDM rubber/reclaimed rubber is used together to produce automotive sealing strips, it is recommended to use two-stage mixing, and one-stage mixing will mix raw rubber, filler, reinforcing agent, softener, etc. evenly; The second stage of mixing is E4LYY422 and the vulcanization system is added to complete the mixing process. It should be noted that the extruded rubber material after EPDM rubber/EPDM reclaimed rubber mixed with rubber must be cooled, and the gas will be precipitated after being parked for a period of time to ensure the compactness of the rubber compound and avoid foaming during continuous vulcanization.
When using EPDM reclaimed rubber to reduce the production cost of EPDM rubber sealing strips for vehicles, the mixing process is very important, which directly affects the performance and life of the sealing strips.
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