Plastic, literally speaking, refers to a plastic material, that is, plastic material. Therefore, clay, gypsum, cement and molten glass are all plastics. Nowadays, plastic refers to the material molded by resin at a certain temperature and pressure.
The yellow translucent sticky substance secreted by some tree trunks is resin. A purple sticky substance secreted by lac insects in India is also a resin and an animal-derived resin. They are all natural resins, and most of the plastics made now are artificial resins.
Dissolve resin in solvent to form paint or coating. Turpentine and shellac have been used as coatings since ancient times. Put the resin in a roller and press it into thin sheets. If it is transparent, it is cellophane. Extruding the solution or melt of resin through holes, drying or cooling to form fibers; After the resin is put into the mold, it is heated and pressed into plastic products. After being transferred underground for several years, natural resin was pressed into amber under certain conditions. This is a natural plastic product, which was used by officials and businessmen in ancient China to make rings, ornaments, cigarette holders and so on.
Chemically speaking, resin is a polymer compound. Cellulose nitrate is a polymer compound. 1846, a 24-year-old young man, Mennard, a chemistry professor in Pelosi's private laboratory, dissolved low-nitrogen nitrocellulose in a mixed solution of ether and ethanol to make a colloidal liquid, which was called collodion from the Greek Kolla, and we translated it into collodion. The solvent in collodion volatilizes, leaving a tough and transparent film. Then at 1848, J. Parker Maynard, a medical student at Harvard University in the United States, published "The Original Application of a Cotton Solution in Surgery" in Boston Journal of Medicine and Surgery. A solution of cotton to Surgey shows that the transparent film left after the solvent in collodion volatilizes can protect the wound by covering the surgical wound with collodion.
This has attracted the attention of some people. Alexander Parkes (18 13- 1890), a metal art dealer in Birmingham, England, made many experiments during the period of 1855- 1862, adding camphor, a little castor oil and pigment to collodion until the solvent volatilized. Made into hilts, women's brooches, earrings, pencil cases, etc. His surname is parksine, which was exhibited at 1862 London International Expo and won a bronze medal. 1866 Paxsing Company was established for production. Due to inaccurate ingredients and other reasons, the company went bankrupt two years later. One of his partners, Daniel Speer (1832-? ) took over the company and changed its name to Salonite, and the product was renamed Salonite.
At the same time, Hai Ete (1837- 1920), a printer in New Jersey, USA, is also trying fake ivory with the same raw material. At that time, due to the lack of ivory and raw materials for making billiards in the United States, a billiards dealer offered a reward of $65,438+$0,000 to collect alternative raw materials for making billiards. At first, Hyatt glued sawdust and shredded paper together, but the quality was poor. Once I accidentally cut my finger and the wound was coated with collodion. I found collodion very sticky, and learned that the British used it to make Paxsin, so I tried it. He just added camphor instead of castor oil to the ethanol and ether solution of nitrocellulose, and tried to prevent the product from shrinking due to solvent volatilization in the molding process, and finally made billiards. So on April 6, 1869, he obtained a patent with the trade name celluloid, which we transliterated as celluloid. 187 1 year celluloid company was established, and 1872 products appeared on the market. It not only makes billiards, but also makes combs, waterproof collars, wrist guards and chest protectors. , and even sold in all parts of China and Japan in Asia (Figure 37- 1). 1898, British Gibb invented celluloid table tennis.
Celluloid has achieved commercial success, surpassing paxson and Si Long Ritter. Hyatt didn't get the bonus, but became a rich man.
Because nitrocellulose is flammable, its application in industrial production is limited. Phenolic resin makes up for this shortcoming. Phenolic resin is the product of the reaction between phenol and formaldehyde (HCHO). Phenol is a product of coal tar and can also be made from benzene in coal tar. Formaldehyde is obtained by methanol oxidation, and 40% formaldehyde aqueous solution is also called formalin, which is a preservative.
Phenolic resin was created by Belgian-born American chemist Backlander (1863- 1944). He received his doctorate in natural science from Ghent University in Belgium, where he worked as an assistant professor of chemistry, and then moved to the United States. He once invented a kind of printing paper that was particularly sensitive to light, won a monopoly, became rich economically, and set up a laboratory in his home to engage in chemical manufacturing research.
Backlander initially tried to make a substitute for Indian shellac. Lac is widely used in coating, papermaking, printing and medicine, and the United States needs to import a large amount from India every year. He read a paper on the reaction between phenol and formaldehyde published by German chemist Bayer in 1872, in which he wrote that a black sticky object was formed during the reaction, which was difficult to remove from the container. Because it is insoluble in water and other solvents, it must be discarded with the container.
So Backlander studied the reaction between phenol and formaldehyde, designed and built a solid reaction kettle, which was successful for two years by increasing the pressure and temperature and selecting the catalyst.
Dr miriam c nagel Backlander's bakelite. Journal of Chemical Education,1980,57 (11).
1907 Backlander issued a patent on heat and pressure. This patent relates to the manufacturing technology of phenolic resin produced by the reaction of phenol and formaldehyde. Backlander added wood chips and other materials to phenolic resin to make various products. 1909, he set up a company named after his own surname, and named the product bakelite after his own surname. We call it bakelite, which is very suitable because of its good electrical insulation, high mechanical strength, heat resistance and water resistance. Widely used in the production of electrical appliances industry to manufacture electrical sockets, lamp holders and switches. Especially after the First World War (1914-1918), the electrical industries such as radio and broadcasting developed rapidly, and the demand for them increased. It has been used to this day. Bakelite is the earliest industrialized plastic in the world, which surpassed celluloid and led to the emergence of new plastics.
Almost at the same time, in 1897, W. Krische, a printer in Hanover, Germany, and Adolf Spitteler, a chemist in Bavaria, made a hard bone-like plastic from casein and formaldehyde, which was marketed as galalith and Egypt. 1909 Latvian chemist Victor Schutze also obtained a patent for this product, which was produced in Britain on 19 13. Casein can be extracted from milk, soybeans, peanuts and other substances, so these substances have also become raw materials for making plastics. Until now, this casein plastic has also been used to make buttons and some handicrafts.
19 18, Hans John, a chemist in slava, Czech Republic, used urea to react with formaldehyde to prepare urea-formaldehyde resin, which can be used to make adhesives or transparent glass-like materials. Urea ((NH2)2CO), also known as urea, exists in the urine of human beings and some animals. It is a white crystal, an important nitrogen fertilizer, a feed for ruminants and a raw material for making plastics.
This kind of urea-formaldehyde resin is different from dark phenolic resin, colorless, light-resistant, high hardness, high strength, non-flammable and light-permeable. After several years of research, Austrian chemist Fritz Pollack found that it can not only transmit light well, but also transmit ultraviolet rays that ordinary silicate glass can't transmit, so it is a good substitute for silicate glass. He made a glass window and assembled it in a university building, but it soon broke. It turns out that urea-formaldehyde resin is easy to absorb moisture in the air when it is wet, but it is easy to release moisture in relatively dry air, which makes this glass break under the action of internal tension. In order to overcome this shortcoming, we decided to use fillers and press them into products by hot pressing. Colorless and transparent water-based resin was mixed with ground cellulose, dried and pressed at the temperature of 140~ 145℃, so that the product was no longer broken, but lost its transparency. Nevertheless, this resin is still used to make clothing products.
Then the British chemist Rossit used thiourea ((NH2)CS, a substance similar to urea) instead of urea to condense with formaldehyde to make thiourea formaldehyde resin. 1926 British cyanide company (later renamed British plastics industry company) was put into production with the trade name of Baertl. Used together with urea-formaldehyde resin to make tableware.
In the 1920s, resin made of furfural instead of formaldehyde appeared again. Furfural, also known as furfural, comes from agricultural and sideline products such as rice bran, cotton husk and corncob, which reduces the price of plastics. In 1930s, melamine (c3h6n 6)- formaldehyde resin appeared again. Melamine is made of calcium carbide, and the plastic made of melamine formaldehyde resin is fireproof, waterproof, oil-resistant and heat-resistant. It is an electrical insulator and can be used as an arc-resistant material.