Commonly molded products processed with EPDM rubber as the main raw material include everything from auto parts, industrial products and other fields, and many of them use EPDM reclaimed rubber to reduce costs. So in actual production, when using EPDM reclaimed rubber to produce low-cost ordinary molded products, how should rubber product manufacturers optimize product performance by adjusting the matching system?
1. Vulcanization system
When using EPDM reclaimed rubber to produce ordinary molded products, sulfur-accelerator system vulcanization is the most common. The sulfur content is adjusted to meet the needs of different processing methods and performance. The rubber compound vulcanized by the common vulcanization system with high sulfur content is mainly cross-linked by polysulfide bonds. The reclaimed rubber vulcanizate has good physical and mechanical properties, poor heat resistance and high temperature permanent deformation; low sulfur or sulfur donors are effective in combination The vulcanization system produces a monosulfur cross-linked network. The EPDM reclaimed rubber vulcanizate has good heat resistance, high temperature permanent deformation, and low mechanical strength; a semi-effective vulcanization system can also be selected for comprehensive mechanical strength and special performance requirements.
EPDM molded products with EPDM reclaimed rubber as the main raw material can also be vulcanized with peroxide. The vulcanized rubber produces a carbon-carbon cross-linked network with high bond energy, good heat aging resistance and compression set resistance, and mechanical strength Low. In EPDM reclaimed rubber molded products, resin curing system and quinone oxime curing system are not common.
2. Reinforcing filling system
Carbon black, white carbon black, calcium carbonate, silicate, clay, talc, etc. are commonly used reinforcing agents and fillers for EPDM reclaimed rubber molded products, and can be selected according to the physical and mechanical properties and processing performance requirements of the products. 2LLYY124 The right variety. Generally, large particle size carbon black can be selected for low-hardness molded products, and the rubber material has better elasticity; for higher hardness requirements, reinforcing carbon black can be selected, and a small amount of talc powder can be used to improve carbon black dispersibility.
The addition of mineral fillers will cause the crosslink density of EPDM vulcanizates to decrease, the tensile strength of vulcanizates and other indicators will decrease, and the compression set will increase. Therefore, it is necessary to control the amount reasonably. Light-colored EPDM molded products can be reinforced with white carbon black, or use white carbon black and soft clay together.
3. Softening and plasticizing system
EPDM reclaimed rubber molded products often use paraffin oil, naphthenic oil or linear polyalkylbenzene oil as softening and speeding agents. EPDM reclaimed rubber is more suitable to use paraffin oil with low volatility and high flash point when producing rubber products that work under high temperature conditions for a long time. When peroxide vulcanization is used, polyalkylbenzene oil is generally used as a plasticizer; when paraffin oil and naphthenic oil are selected as the softening and plasticizing system, it is necessary to appropriately increase the amount of peroxide.
When ordinary molded products with EPDM reclaimed rubber as the main raw material are vulcanized with peroxide, rubber product manufacturers also need to pay attention to the reaction between acidic fillers and peroxides, and use metal oxides or aromatic amines to neutralize the rubber. with. Regarding the design of the matching system for ordinary EPDM molded products, there are still many issues that need attention. I will continue to discuss with you later.
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