EPDM belongs to non-polar rubber, with weak chemical reactivity, low surface energy and poor adhesion. It is easy to have poor adhesion when vulcanizing with metal, so appropriate measures should be taken. Rubber and metal bonding methods include direct bonding and indirect bonding. Ethylene propylene rubber and metal bonding are commonly used indirect methods. When bonding, it requires not only sandblasting, pickling, phosphating, electroplating and other treatments on the metal surface, but also correct selection of bonding process and adhesive system with strong adhesion.
To improve the adhesion among EPDM and metal, the following principles should be followed.
1. Select appropriate bonding system
When EPDM was bonded to metal, the "m-methyl-white" system consisting of resorcinol (tackifier RS), formaldehyde donor (tackifier RH) and precipitated silica could significantly improve the adhesive strength of EPDM; Generally, the dosage of tackifier RS and RH is among 1.5-3.5 phr, and the dosage of white carbon black is controlled at about 10 phr.
2. Select appropriate ethylene propylene rubber
In actual production, selecting EPDM raw rubber with low ethylene content, low oil content, medium or relatively high molecular weight and diene content can improve the reactivity of rubber compound, and then improve the bonding strength among EPDM rubber compound and metal.
3. Use of tackifier
When EPDM rubber needs to be bonded to the metal skeleton, appropriate use of rosin derivatives, terpene resins, alkyl phenolic resins, coumarone resins, petroleum resins and asphalt and other viscosity increasing substances in the EPDM product formula can significantly improve the adhesion strength of EPDM. In actual production, proper increase of carbon black content is conducive to bonding, in which carbon black with high reinforcement and structure has higher surface activity, which can simultaneously improve the strength and bonding strength of EPDM vulcanizate.
4. Reduce the dosage of compounding agent unfavorable to adhesion
Softener is not good for improving adhesion, so it is necessary to control the amount of softener in the formulation of EPDM rubber products within a certain range. The migration of processing aids such as paraffin wax, microcrystalline wax, lubricant, internal release agent and easily ejected material 2ELYY1229 to the bonding interface will reduce the bonding strength. The adhesive materials required to be bonded should generally be avoided. If they must be used, they must be controlled within the allowable amount.
EPDM rubber is a kind of synthetic rubber with high price. When producing rubber products with EPDM as the main raw material, EPDM recycled rubber can be used appropriately to replace EPDM rubber. The above principles can also be followed to improve the adhesion among EPDM/EPDM recycled rubber and metal; Later, Xiaobian will continue to share with you specific measures to improve the adhesion among EPDM/recycled rubber and metal skeleton.
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