Bakelite is phenolic resin. Phenolic resin (PF) is a kind of industrial plastic products. The raw materials of phenolic resin production are mainly phenol and aldehyde, and phenol and formaldehyde are commonly used. They are polymerized by condensation reaction under the catalysis of acid, base and other catalysts. There are two kinds of industrial production: dry process and wet process.
Under the action of different catalysts, phenol and aldehyde can produce two kinds of phenolic resins: one is thermoplastic phenolic resin, the other is thermosetting phenolic resin. The former can be cured into block structure by adding curing agent and heating, while the latter can be cured into block structure by heating without adding curing agent.
Thermoplastic phenolic resin and thermosetting phenolic resin can only be used through the exchange network formed by curing. The curing process is the continuation of shape polycondensation and the formation of shape products. This process is different from the melting and curing of general thermoplastics. Both physical and chemical processes are irreversible.
Phenolic resin can be injection molded in a similar way to thermoplastic. PF for injection molding requires good fluidity, can be molded under low injection pressure, high thermal stiffness, fast hardening speed, good surface gloss of plastic parts, easy demoulding, and no mold pollution. However, injection molding also has its disadvantages. For example, the melt is limited by the type of filler, so it is not suitable to use more inserts to form plastic parts. A large number of gates and channels cannot be recycled after curing, and can only be discarded.
In a word, thermoplastic phenolic resin can be produced by ordinary injection molding machine, but the process conditions are strictly controlled. Thermosetting phenolic resin must be produced by a special injection molding machine for phenolic resin, and the mold also adopts a special design structure.
It is widely used in electrical accessories, sockets, lamp holders, sandwich machine shells, etc; However, its fragile performance and troublesome pressing process may limit its development. With the emergence of other plastics, bakelite products are not easy to see now. Although bakelite products need to be heated for molding, the processing time is longer than that of ordinary plastics, and the mold wear is larger, which requires higher requirements for steel, but because of its advantageous position in the price of raw materials, it is still a substitute for many plastic parts.
Post time: Jul-15-2022