What is EPDM reclaimed rubber? EPDM reclaimed rubber is a recycled rubber resource made from waste EPDM rubber sealing strips and other waste EPDM products, retaining the basic performance characteristics of EPDM base rubber. Rubber sealing strips are sealing products that use the elasticity of the lip, cavity, flange, and other parts to generate contact pressure on the surface of the object in contact to achieve sealing. The rubber material must have good processing safety, low Mooney viscosity, good tensile properties, resistance to permanent compression deformation, and aging resistance. Is EPDM reclaimed rubber suitable for making rubber sealing strips?
1. Feasibility analysis of rubber sealing strips for producing EPDM reclaimed rubber
In terms of performance, EPDM reclaimed rubber excels in high and low temperature resistance, ozone resistance, and weather resistance, meeting the aging resistance requirements of rubber sealing strips. From the processing technology perspective, ethylene propylene diene diem reclaimed rubber E6LYY42 better plasticity than raw rubber and easier to mix with raw rubber and additives; Good flowability, fast rolling and extrusion speeds, low shrinkage during rolling and low expansion during extrusion, and few appearance defects in semi-finished products; Vulcanization is fast, with a low tendency to revert to its original sulfur. In terms of price, EPDM reclaimed rubber is much cheaper than EPDM raw rubber, and its use in rubber sealing strip production can effectively reduce raw material costs.
Therefore, EPDM reclaimed rubber can be used in the production of rubber sealing strips, improving the processing performance of rubber materials, reducing sealing strip production costs, and increasing the economic benefits of enterprises.
2. Key Points for Formula Design for Rubber Sealing Strips in the Production of EPDM Reclaimed Rubber
(1) Application methods of EPDM reclaimed rubber in rubber sealing strips
When producing rubber sealing strips with EPDM reclaimed rubber, EPDM reclaimed rubber can be used alone, combined with EPDM rubber, natural rubber, or blended with rubber-plastic blends; It is necessary to fully consider the ozone and aging resistance requirements of sealing strips, and reasonably determine the application method and addition ratio of EPDM reclaimed rubber in sealing strips.
(2) Tips for selecting EPDM reclaimed rubber for rubber sealing strips
When using EPDM reclaimed rubber for rubber sealing strips to reduce costs, it is recommended to choose 60-80 mesh EPDM reclaimed rubber, which has high fineness and avoids impurity contamination; Select EPDM reclaimed rubber with a hardness of 60-80 degrees, tensile strength of ≥8MPa, and elongation at break ≥of 300% to provide the basic mechanical properties for rubber sealing strips; EPDM rubber sealing strips with strict environmental requirements can use environmentally friendly EPDM reclaimed rubber certified by EU RoHS.
(3) Key points for formula design for rubber sealing strips produced by EPDM reclaimed rubber
(1) Vulcanization system: When producing rubber sealing strips with EPDM reclaimed rubber, it is recommended to use a peroxide vulcanization system or an effective vulcanization system, as reclaimed rubber vulcanized rubber has better heat resistance; When using sulfur vulcanization, the amount of sulfur is generally controlled among 0.5 and 1.5 parts, combined with accelerators such as TMTD and CZ.
(2) Reinforcement system: EPDM reclaimed rubber has lower strength than EPDM, so high-wear-resistant carbon black can be used for reinforcement, such as N330 or N550, with dosages of 40-60 parts, and can be used with silica or clay.
(3) Softening and plasticizing system: Adding softeners such as naphthenic oil, paraffin oil, or paste into the EPDM reclaimed rubber sealing strip formulation in 10-20 parts can improve the extrusion performance of the compound. The grease also enhances the elasticity of the compound and reduces deformation during storage, which is especially important for the structural and dimensional stability of the special-shaped sealing strip.
(4) Anti-aging system: Reasonable use of antioxidants RD, 4010NA, or AW to further improve the aging resistance of EPDM reclaimed rubber sealing strips.
(5) Extrusion process adaptation: EPDM reclaimed rubber sealing strips are mostly formed by continuous extrusion, requiring good flowability, smooth surface, and non-scorching of the compound. Appropriately combining lubricants such as stearic acid and paraffin can improve the plasticity of the compound, effectively enhancing extrusion speed and the appearance quality of the finished product.
EPDM reclaimed rubber has good aging resistance, low cost, and is easy to process. It can be used alone or combined with EPDM rubber and butyl rubber to produce rubber sealing strips suitable for building door and window sealing, ordinary automotive door and window seals, static seals for mechanical equipment, cable sheath sealing, and other scenarios; Reasonably designing the EPDM reclaimed rubber sealing strip formula can fully leverage the cost-performance advantage of reclaimed rubber and produce more high-quality sealing strips that are both economical and durable.
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