EPDM recycled rubber has excellent high and low temperature resistance, ozone resistance, and weather resistance, and can be used alone or in combination with EPDM to produce various automotive seals, effectively reducing raw material costs. Automotive seals are required to have good weather resistance, ozone resistance, sunlight aging resistance, compression set resistance, etc. When using EPDM recycled rubber to produce automotive sealing strips, the performance requirements of sealing strips in different parts are different.
Automotive rubber seals can be divided into solid rubber strips and sponge rubber strips according to the structure of rubber materials, and different varieties of automotive rubber seals use different compounds.
1. Design of vulcanization system for the production of EPDM recycled rubber for automobile sealing strips
(1) EPDM recycled rubber solid rubber strip vulcanization system: commonly used sulfur-accelerator system, the amount of accelerator is large, generally follow the principle of multiple varieties, less dosage, avoid frost spraying; When the automobile solid sealing strip has extremely high requirements for heat resistance and aging resistance, the peroxide vulcanization system can be used, which is only suitable for the salt bath continuous vulcanization method.
(2) EPDM recycled rubber sponge strip vulcanization system: sulfur vulcanization system is the most commonly used, and the amount of vulcanization system compound is larger than that of solid glue formula; Peroxide vulcanization systems are limited to salt bath vulcanization.
2. Design of EPDM recycled rubber production of automobile sponge sealing strip foaming system
When using EPDM recycled rubber as the main raw material to produce automotive sponge foam rubber sealing strips, commonly used blowing agents include AC, OBSH, TSH, etc. The smaller the particle size of the blowing agent, the larger the surface area, so the heat transfer is more effective, thereby improving the efficiency of the blowing agent. In order to reduce the thermal decomposition temperature of the blowing agent, some foaming auxiliaries can be used. For example, zinc oxide can be used as a foaming aid for AC, and TEA can be used as a foaming aid for sulfonylhydrazines.
3. Design of EPDM recycled rubber production automobile sealing strip reinforcement filling system
(1) EPDM recycled rubber solid rubber strip reinforcement filling system: adopt fast pressure furnace black, semi-reinforced furnace black, general furnace black and other varieties with good extrusion performance and reinforcement effect, such as N550, N650, N774, SP5000 carbon black, etc. The filler is mostly calcium carbonate, talc, clay and other mineral fillers and carbon black.
(2) EPDM recycled rubber sponge strip reinforcement filling system: N600 and N700 series carbon black is easy to disperse, used in the production of EPDM recycled rubber sponge strips, a finer E5LYY917 sponge structure can be obtained, too much carbon black will lead to uneven foaming size of EPDM recycled glue; The use of mineral fillers with smaller particle size as auxiliary fillers for automotive EPDM recycled adhesive seals can not only reduce costs, but also act as a nucleating agent for foaming, improving the uniformity of sponge structure.
It is recommended that when using microwave (UHF) continuous vulcanization, N550 carbon black should be used on the one hand to ensure the balance of solid glue and sponge adhesive on UHF energy absorption. On the other hand, by adding white mineral fillers (such as fine-grained calcium carbonate, etc.), the absorption of UHF energy by solid rubber can be inhibited.
4. Design of EPDM recycled rubber production automobile sealing strip softening system
(1) EPDM recycled rubber solid rubber strip softening system: mostly paraffin-based oil, naphthenic oil or aromatic oil with good compatibility with EPDM. Paraffin-based oil has the characteristics of high saturation, low volatile content, light color, high temperature resistance and excellent UV resistance. Naphthenic oil has the characteristics of excellent low temperature resistance and good color stability, and has better compatibility and higher tensile strength and tear strength than paraffin-based oil. Aromatic oil has the characteristics of high aromatic hydrocarbon content (better compatibility with EPDM) and low volatile content, but it has potential carcinogenic risks.
(2) EPDM recycled rubber sponge strip softening system: paraffin-based oil and naphthenic oil are usually selected for operating oil.
When using EPDM recycled rubber to produce rubber seals in different parts, sealing strip manufacturers can choose the appropriate EPDM recycled rubber according to actual needs, reasonably determine the mixing ratio of recycled rubber, and later share with you the low-cost vulcanization formula of EPDM rubber/EPDM recycled rubber and solid rubber and sponge sealant strips.
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