The performance characteristics of friction materials determine the production process
Phenolic resin is an important component in the structure of friction materials, and it is important to understand its process performance characteristics. The molding process can be divided into casting molding and compression molding. The production of phenolic friction materials uses a hot press forming process. There are two reasons why phenolic pressed plastics are solidified and molded under heating and pressure conditions. The first is the fluidity factor of pressed plastic. In the production of friction materials, in order to obtain the required friction performance and mechanical strength of the friction materials, the dosage of fillers and fiber reinforcements usually accounts for 80% to 90% of the formula components, while the dosage of resin binders is only It accounts for 10%~20%, so the fluidity of its pressed plastic is relatively poor. If the casting molding process is used, the pressed plastic cannot be filled with the wood cavity to obtain a molded product.
We usually have to use a heating and pressurizing molding process, so that the pressed plastic flows under a certain pressure in the mold cavity heated to the curing temperature (170~180°C), fills the mold cavity, and is cured by heat, thereby obtaining cured molding. products. The second is that the phenolic resin in the compression plastic further undergoes a polycondensation reaction at the curing temperature, gradually transforming from a linear structure or a branched chain structure into a three-dimensional cross-linked network structure, and finally solidifies. During this process, the resin will release moisture and other low-molecular substances, which will generate large steam pressure at the molding temperature (150°C). If they escape from the surface of the molded product, the product will be damaged and scrapped. Therefore, the products in the mold need to maintain a high molding pressure before they are fully solidified.
