Bakelite Material used in CNC factory
Basic Introduction
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 often used to manufacture electrical materials, such as switches, lamp holders, headphones, telephone cases, instrument cases , etc., hence the name "Bakelite".
The advent of Bakelite is of great significance to industrial development.
Mechanical properties
Bakelite is a hard and brittle thermosetting material.
The characteristics of bakelite are that it does not absorb water, does not conduct electricity, is resistant to high temperatures, and has high strength. It is often used in electrical appliances. It is also called "bakelite" because it has high insulation and good plasticity like wood. Bakelite is made from powdered phenolic resin, which is mixed with sawdust, asbestos or clay, and then pressed into a mold at high temperatures to produce the finished product. Phenolic resin is the world's first artificially synthesized resin.
Phenolic plastic (Bakelite): The surface is hard, brittle and easy to break. It makes a sound like a wooden board when knocked. It is mostly opaque and dark (brown or black). It does not soften in hot water. It is an insulator, and its main component is phenolic resin.
Forming performance
Feature
1. It has good moldability, but its shrinkage and orientation are generally greater than those of amino plastics , and it contains water and volatiles. It should be preheated before molding and exhausted during molding. If it is not preheated, the mold temperature and molding pressure should be increased.
2. Mold temperature has a great influence on fluidity. Generally, when it exceeds 160 degrees, fluidity will drop rapidly.
3. The hardening speed is generally slower than that of amino plastics, and the heat released during hardening is large. The internal temperature of large thick-walled plastic parts is prone to be too high, which is prone to uneven hardening and overheating.
Usage
When the formaldehyde/phenol (molar ratio) is less than 1, a thermoplastic product can be obtained, which is called thermoplastic phenolic resin, that is, linear phenolic resin . It does not contain further condensation groups and can only be cured by adding a curing agent and heating. For example, hexamethylenetetramine is used as a curing agent, the curing temperature is 150 ° C, and the molding powder mixed with fillers is commonly known as bakelite powder. When the formaldehyde/phenol (molar ratio) is greater than 1, the first stage A resin, that is, thermosetting phenolic resin, is obtained under alkali catalysis. It can be dissolved in organic solvents. The A stage resin contains hydroxymethyl groups that can further condense, so it can be cured without adding a curing agent: the B stage resin is obtained by heating, also known as semi-soluble phenolic resin, which is insoluble and infusible but can swell and soften. Further reaction will obtain the insoluble and infusible bulk structure C stage resin, also known as insoluble phenolic resin. The A stage resin can also cure itself after long-term storage.
The curing forms of thermosetting phenolic resin are divided into room temperature curing and heat curing. Room temperature curing can use non-toxic room temperature curing agent NL, or benzenesulfonyl chloride or petroleum sulfonic acid, but the latter two materials are more toxic and irritating.
