The emergence of bakelite
1905 One day, the German chemist Bayer experimented with phenol and formaldehyde in a flask and found something sticky in it. He washed it with water, but it didn't come off, and he changed organic solvents such as gasoline and alcohol, but it still didn't work. This made Bayer's brain break. Later, he tried his best to finally get this disgusting thing down. Bayer breathed a sigh of relief and put it down.
A few days later, Bayer wanted to dump these things into the trash can. At this moment, he saw that thing again. The surface is smooth and shiny, with an attractive luster. Bayer took it out curiously and put it on the fire for barbecue. It stopped softening and fell to the ground, but it didn't break. Saw it with a saw. It sawed well. The keen Bayer immediately thought that this might be a good new material.
After people's experiments, it is found that this once "annoying" thing is really "pleasing" now. It is impervious to water, does not deform when heated, has certain mechanical strength, is easy to process, and has good insulation, so it is simply an ideal choice for emerging electrical industries. Therefore, it is widely used in the production of switches, light switches, lamp holders, telephones and other electrical appliances, hence the name "bakelite". Until now, bakelite is still the most important, largest output and most widely used plastic.
Phenolic molding compound, also known as bakelite powder, has good insulation performance and is used to manufacture electrical appliances and daily industrial products. It is made of phenolic plastic with wood flour as filler by pressing.
When the molar ratio of formaldehyde to phenol is less than 1, a thermoplastic product can be obtained, which is called thermoplastic phenolic resin, that is, linear phenolic resin, which contains no further polycondensation groups and can be cured only by adding curing agent and heating. If hexamethylenetetramine is used as curing agent and the curing temperature is 150℃, the molding powder made of filler is commonly called phenolic molding compound. When the molar ratio of formaldehyde to phenol is greater than 1, the first-class resin, thermosetting phenolic resin, can be obtained under the catalysis of alkali, which can be dissolved in organic solvents. The primary resin contains hydroxymethyl which can be further condensed, so it can be cured without curing agent. The second-stage resin is also called semi-soluble phenolic resin, which can be obtained by heating and reacting. It is insoluble, but can swell and soften. After further reaction, the insoluble and insoluble bulk structure C-grade resin, also known as insoluble phenolic resin, was obtained. A-grade resin can also cure itself after long-term storage.
Formaldehyde is toxic to human body, mostly stimulated by gas and inhaled by people. There are two ways to avoid this kind of injury. First, spray paint all the surfaces of plywood for many times to prevent the decomposed formaldehyde gas from spreading to the outside. Brush all surfaces many times, which is impossible for ordinary people, otherwise the cost will be higher than that of using solid wood. 2. Remove formaldehyde gas before it diffuses into the air or into the air. This is the starting point for manufacturers to operate under the slogan of "high technology".