Flange sealing gaskets are mainly used in pipelines, valves, pump bodies, and equipment flange connections, serving to seal the medium and prevent leakage; Flange gaskets in different usage environments have varying requirements for heat resistance, weather resistance, compressive resilience, and media resistance of the rubber compound. EPDM reclaimed rubber is made from EPDM machine head rubber, unvulcanized compound, or waste EPDM rubber products, retaining the basic properties of EPDM base rubber. It can be used together with EPDM rubber to produce flange sealing gaskets, meeting usage requirements while reducing raw material costs.
1. Application advantages of EPDM reclaimed rubber in producing flange sealing gaskets
Flange sealing gaskets are in a long-term bolt pre-tension compression state, requiring the compound to have appropriate hardness, elasticity, and permanent compression deformation. EPDM reclaimed rubber has good weather resistance, ozone resistance, and water resistance, as well as certain tensile strength and hardness, meeting the basic performance requirements of flange sealing gaskets. It can be used together with EPDM rubber to produce outdoor pipelines, water supply and drainage equipment, sewage treatment facilities, and some flange gaskets in seawater environments.
Compared to using all EPDM rubber, EPDM reclaimed rubber is cheaper and has better plasticity and flowability; Reasonable blending of EPDM reclaimed EPDM reclaimed rubber in flange gaskets can reduce raw rubber costs and improve the processing performance of the rubber material; 20%-60% EPDM reclaimed rubber can be added to medium- and low-pressure flange gaskets, with the specific dosing ratio determined by the quality of the reclaimed rubber and the finished product performance.
2. Key points for formula design of flange sealing gaskets for the production of EPDM reclaimed rubber
When producing flange gaskets using EPDM rubber and reclaimed EPDM rubber, the formulation design must balance compression rebound, anti-aging, and processing stability.
Flange sealing gasket vulcanization systems using EPDM reclaimed rubber should be selected based on operating temperature and performance requirements. For general environments, a sulfur-accelerator system can be used E6LYY725, while for products with high requirements for heat resistance and compression permanent deformation, DCP peroxide vulcanization systems are recommended; For reinforcing filler systems, N330, N550, or N774 carbon black can be selected, combined with fillers such as calcium carbonate, kaolin, and talc powder to adjust hardness and cost; For the softening system, materials such as paraffin oil and paste can be used to improve the processing performance of the compound compound, with reasonable control of softener dosage to avoid excessive softening affecting the gasket's compression permanent deformation.
3. Key Points of the Flange Sealing Gasket Manufacturing Process for EPDM Reclaimed Rubber
When producing flange sealing gaskets with ethylene propylene diene diem rubber and reclaimed EPDM rubber, whether the packing dispersion is uniform and the compound temperature is stable will affect the subsequent molding quality.
During the mixing process of EPDM rubber and EPDM reclaimed rubber, the starting temperature can be controlled among 35-55°C, and the powder discharge temperature can refer to 105-120°C, adjusted according to equipment, filling amount, and formula; After mixing, molding or curing the rubber sheet is performed according to product dimensions and structure, followed by cutting; The vulcanization temperature, time, and pressure should be determined based on vulcanization test results and the thickness of the EPDM reclaimed rubber flange. If necessary, segmented vulcanization or post-vulcanization processes should be used to improve gasket performance stability.
When adding EPDM reclaimed rubber to flange sealing gaskets, it is recommended to select EPDM reclaimed rubber with appropriate specifications based on the specific performance requirements of the gasket. EPDM reclaimed rubber Grade 1 uses EPDM die head rubber and unvulcanized EPDM rubber as the main raw materials. After sorting and crushing, it is filtered and molded into a twin-screw 80-mesh dual-channel system, retaining over 90% of the original molecular weight and rubber chain structure. It features no migration, resistance to high and low temperatures, aging resistance, smooth and bright product surface, labor and electricity saving, and simple smelting process. Used in flange sealing gasket production, it reduces production costs by an average of 20%.
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