Solving Dirt on EPDM Rubber Product Molds

EPDM rubber has a low density, allowing for significant filler and rubber oil content without major changes in physical and mechanical properties. However, in practical production, the rubber oil used for filling may contain volatile components, leading to mold deposits. How can this issue be resolved? What other factors contribute to mold deposits in the production of EPDM rubber products, and how can rubber product manufacturers address them?

1. Skillful selection of rubber filling oil: When filling EPDM rubber products with a large amount of rubber oil, choosing low-volatility rubber oil can reduce deposits. If volatile rubber oil must be used, the quantity can be appropriately reduced, or an oil-in-rubber substitute can be used instead. In practical production, petroleum-based rubber oil tends to volatilize under high-temperature conditions.

2. Skillful selection of other additives: EPDM rubber product vulcanization systems consist of vulcanizing agents and accelerators. The addition of certain accelerators, such as TMTD (which is prone to blooming), can cause mold deposit issues. It is important to select a vulcanization system that minimizes deposits. TBTD can be tried as a substitute for TMTD. The cautious use of mold release agents helps reduce mold deposits. The appropriate use of specialty additives effectively reduces the occurrence of deposits.

3. Enhancing heat tear resistance of EPDM rubber: Experimental studies have shown that better heat tear resistance of the rubber compound leads to easier mold release and reduced mold deposits. In practical production, filling EPDM rubber compounds with a large amount of coarse mineral fillers can decrease heat tear resistance. Therefore, reducing filler content and adopting measures to improve heat tear resistance can minimize mold deposits.

4. Adjusting the curing conditions: When producing EPDM rubber products, especially injection-molded EPDM products, longer curing at lower temperatures reduces the occurrence of mold deposits. When using a combination of EPDM reclaimed rubber and EPDM virgin rubber, manufacturers need to consider the basic properties of both types of rubber and determine the optimal curing conditions.

Currently, many EPDM rubber product manufacturers use EPDM reclaimed rubber to reduce material costs. In practical production, formulations containing EPDM reclaimed rubber have lower rubber filler and oil content compared to formulations using pure virgin rubber, which helps reduce deposits to some extent. However, it is crucial not to choose reclaimed rubber softened with volatile rubber oil when reducing costs by using EPDM reclaimed rubber to avoid mold deposits.

Compared to EPDM virgin rubber, EPDM reclaimed rubber has better flowability, higher plasticity, and lower heat sensitivity. Its use in EPDM product manufacturing not only reduces material costs but also improves rubber processing. In the future, I will have the opportunity to discuss techniques for cost reduction using EPDM reclaimed rubber in EPDM rubber product manufacturing.

Email: grace@gofairubber.com