The rubber seat of the butterfly valve is one of the key components of the butterfly valve, which is mainly used to realize the sealing function of the butterfly valve. EPDM reclaimed rubber has excellent weather resistance, ozone resistance and chemical corrosion resistance, and can maintain a good sealing effect for a long time in the production of butterfly valve rubber seats, and is widely used in various industrial and civil fields. EPDM reclaimed rubber and a small amount of raw rubber are used together to produce butterfly valve rubber seats, which can further improve the elasticity of valve seats.
1. EPDM reclaimed rubber and a small amount of original rubber are used together to produce butterfly valve vulcanization formula
10 parts of EPDM rubber 4045, 90 parts of ethylene propylene reclaimed rubber of secondary EPDM, 3 parts of zinc oxide, 1.8 parts of stearic acid, 1 part of paraffin, 0.07 parts of deodorant, 5 parts of carbon black N550, 36 parts of rubber reinforcing agent, 7 parts of paraffin oil, 0.5 parts of accelerator CZ, 0.45 parts of accelerator DM, 0.15 parts of accelerator TMTD, 1.33 parts of sulfur; Total 156.3 copies.
2. EPDM butterfly valve rubber seat performance requirements
The rubber seat of the EPDM butterfly valve will be exposed to the natural environment for a long time during use, and the rubber material is required to have good weather resistance and ozone resistance, and it is not easy to age and crack when used in harsh environments; It can effectively resist the erosion of chemical media E4LYY820 ensure the sealing performance of the butterfly valve; It has good elasticity and flexibility, can adapt to the slight deformation of the butterfly plate, ensures the reliability of the seal, and is not easy to become brittle at low temperature; Stable performance over a wide temperature range.
When using EPDM reclaimed rubber instead of EPDM raw rubber to produce butterfly valve rubber seats, it is necessary to fully consider the physical property requirements and cost budget of rubber valve seats, select appropriate EPDM reclaimed rubber, and reasonably design rubber formulas.
3. EPDM reclaimed rubber production butterfly valve rubber seat formula design points
(1) Selection of rubber raw materials
When EPDM reclaimed rubber is combined with a small amount of raw rubber to produce butterfly valve rubber seats, it is recommended to choose EPDM reclaimed rubber with high ethylene content and EPDM rubber with high ethylene content (such as 65%-70%) to improve the heat resistance and chemical corrosion resistance of the rubber.
(2) Vulcanization system design
The selection of vulcanization system has an important impact on the performance of the valve seat, and the vulcanization systems commonly used in the production of butterfly valve rubber seats by EPDM reclaimed rubber include sulfur-accelerator system and peroxide vulcanization system. In the sulfur-accelerator system, accelerator CZ and accelerator DM are commonly used with sulfur; The peroxide vulcanization system is suitable for applications that require no sulfurization reversion.
(3) Reinforcement system design
Carbon black is a commonly used reinforcing agent, which can improve the mechanical strength and wear resistance of EPDM butterfly valve seat, and the commonly used carbon black varieties include N330, N550, etc.; To improve the tensile strength, tear strength and wear resistance of vulcanized rubber, N550 can also improve the processing performance of the rubber, reduce heat generation, and improve the corrosion resistance and aging resistance of the rubber. Fill with calcium carbonate, clay or rubber reinforcing agent to further reduce production costs.
(4) Softening system design
Paraffin oil is a commonly used rubber processing aid in the production of rubber butterfly valve and rubber valve seat, which can play a role in plasticizing, softening, lubricating and improving processing performance; Dioctyl phthalate (DOP) can improve the flexibility and processability of compounds.
4. EPDM reclaimed rubber production butterfly valve rubber seat processing points
When EPDM reclaimed rubber is combined with a small amount of raw rubber to produce butterfly valve rubber seats, the segmented mixing method is generally adopted, and the first stage of mixing is carried out in the internal mixer, and rubber raw materials, carbon black, reinforcing agent, deodorant, paraffin, paraffin oil, zinc oxide, stearic acid, etc. are added; The second stage of mixing adds sulfur and accelerator, and the open mill is thinly fed. EPDM reclaimed rubber valve seat is generally vulcanized at a temperature of about 160°C, and the vulcanization time is determined according to the product.
The use of EPDM reclaimed rubber in the rubber seat of the butterfly valve can not only reduce costs, but also meet the high-performance requirements of the valve seat in terms of weather resistance, ozone resistance, chemical corrosion resistance, elasticity and flexibility. In the future, Xiaobian will continue to share with you the application skills and practical formulas of EPDM reclaimed rubber in other rubber products.
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