Bakelite, also known as bakelite, is a phenolic plastic filled with wood flour. Bakelite has good electrical insulation properties and high temperature resistance, and is especially suitable for the production of electronic appliances, daily-use industries and automotive parts. Bakelite molding process is also relatively wide, and can be used in injection molding, die casting, transfer molding and other processes.
Characteristics of Bakelite Injection Products
Bakelite is the first type of plastic to be put into industrial production. The chemical name of Bakelite is phenolic plastic. It has high mechanical strength, good insulation, heat resistance and corrosion resistance. Therefore, it is commonly used in the manufacture of electrical materials. Switches, lamp holders, earphones, telephone casings, instrument cases, etc., "Bakelite" is named after this.
Phenolic plastic is a hard and brittle thermoset material.
The characteristics of bakelite are non-absorbent, non-conductive, high-temperature resistant, high-strength, and are often used in electrical appliances. Because of its high insulation and good plasticity like wood, it is called “bakelite”. Bakelite is a powdered phenolic resin which is added to sawdust, asbestos or clay and mixed with a mold at a high temperature. The phenolic resin is the world's first synthetic resin.
Phenolic plastic (bakelite): The surface is hard, brittle and fragile. It has a sound of wood and is mostly opaque dark (brown or black). It does not soften in hot water. It is an insulator whose main component is phenolic resin.
1. Good formability, but shrinkage and directionality are generally larger than aminoplasts and contain moisture volatiles. It should be preheated before molding, and should be vented during the molding process. If it is not preheated, the mold temperature and molding pressure should be increased.
2. The mold temperature has a great influence on the fluidity, and when it exceeds 160 degrees, the fluidity will drop rapidly.
3. The hardening speed is generally slower than that of aminoplasts, and the heat released during hardening is large. The internal temperature of large thick-walled plastic parts tends to be too high, and it is prone to hardening unevenness and overheating.
When the formaldehyde/phenol (molar ratio) is less than 1, a thermoplastic product is obtained, which is called a thermoplastic phenolic resin, that is, a novolak type phenolic resin, which does not contain a further polycondensation group, and is cured by adding a curing agent and heating. For example, hexamethylenetetramine is used as a curing agent, and the curing temperature is 150 ° C. The molding powder mixed with the filler is commonly known as bakelite powder. When the formaldehyde/phenol (molar ratio) is greater than 1, a base-stage resin, that is, a thermosetting phenolic resin, which is soluble in an organic solvent and contains a methylol group capable of further polycondensation, is not required under base catalysis. Adding a curing agent can cure: the reaction is heated to obtain a B-stage resin, also known as a semi-dissolved phenolic resin, which is insoluble and infusible but swellable and soft. Further reaction results in an insoluble and infusible bulk structure, a C-stage resin, also referred to as an insoluble phenolic resin. The long-term storage of the stage A resin also cures itself.
The cured form of the thermosetting phenolic resin is classified into two types: room temperature curing and heat curing. Normal temperature curing can use non-toxic room temperature curing agent NL, but also benzenesulfonyl chloride or petroleum sulfonic acid, but the latter two materials are more toxic and irritating.