At the beginning of the 20th century, it was considered incredible for enterprises to engage in basic scientific research. DuPont, which attaches importance to the research and development of new products, believes that scientific research can promote industrial production. So in 1926, Charles Stein, the research director of DuPont, proposed to carry out some basic research.
In 1927, DuPont decided to pay US $250000 a year as research expenses and began to hire chemical researchers.
In 1928, the Institute of basic chemistry was established. At the age of 32, Dr. Wallace carrothers was employed as the head of the Department of mechanical chemistry. Stein's requirement is to "only explore the objective phenomena related to the characteristics and properties of various substances, and don't care about the specific uses of the discovered phenomena." Carothers is a doctor of organic chemistry at the University of Illinois. After graduating in 1924, he successively taught and studied organic chemistry at that university and Harvard University, He highly praised the polymer theory put forward by the German scientist h. Staudinger, which was not accepted at that time.
After being employed by DuPont company in 1928, Carothers presided over a series of studies on obtaining high molecular weight substances by polymerization based on stodinger's high molecular weight theory. He first invented neoprene and then began to study the polymerization of polyester.
In 1930, carrothers' assistant found that the polyester prepared by condensation of ethylene glycol and sebacic acid could extract the silk like cotton candy. Even after cooling, the extracted silk would not harden or break, the length could reach several times of the original, and the strength and elasticity were greatly increased. They had a premonition that this characteristic could be used to spin fibers, but continued research showed that the fiber obtained from this polyester was only of theoretical significance, because it melted below 100 ℃, and was particularly soluble in various organic solvents, but it was slightly stable in water, so it was not suitable for weaving. In fact, on the basis of absorbing these research results, T.R. whinfield snow in Britain used terephthalic acid and diol for polycondensation, and successfully synthesized polyester fiber polyester in 1940, which is a pity for carrothers.
The wheel of history is advancing rapidly. Less than two years after the founding of DuPont's Institute of basic chemistry, the U.S. economy entered the great depression. Fortunately, DuPont's basic research projects did not dissolve even in the great depression, but the difficult times also brought greater pressure to the laboratory of Carothers. They must develop a marketable synthetic fiber to replace the existing ones Outdated rayon. Carothers' team has submitted about 60 patent applications, but as Elmer Bolton, the new research director, likes to say, none of them made him hear the "jingle of cash register". Later, Carothers turned his research focus to polyamide and applied for the previous polyamide patent in 1931 （ＵＳＰ２１３０９４８）。
At the beginning of 1935, the strength and elasticity of PA fiber synthesized by him with glutamine and sebacic acid exceeded that of silk, and it was not easy to absorb water and difficult to dissolve, but the melting point was low and the raw materials were expensive.
On February 28, carrothers synthesized PA66 from hexanediamine and adipic acid with 6 carbon atoms each. The first 6 represents the number of carbon atoms in diamine and the second 6 represents the number of carbon atoms in adipic acid. The appearance and luster of the fiber drawn by this polymer are no less than that of natural silk, and the wear resistance and strength exceed any fiber at that time. DuPont decided to carry out commercial production However, to turn the achievements of the laboratory into commodities, one is to solve the industrial source of raw materials; the other is to develop production technologies and equipment such as transportation, metering and winding in the melt spinning process.
Adipic acid and hexamethylene diamine, the raw materials required for the production of PA66, were only used as reagents in the laboratory at that time. It was necessary to develop and produce adipic acid and hexamethylene diamine in large quantities and at an appropriate price. DuPont chose rich phenol for development experiments. In 1936, it finally developed a new catalytic technology, which can produce adipic acid in large quantities with cheap phenol, and then invented the use of phenol The new process of producing hexanediamine from adipic acid solves the problem of raw material source of PA66. DuPont also pioneered a new melt spinning technology.
In July 1938, DuPont completed the pilot test and produced PA66 fiber for the first time. In the same month, the toothbrush with PA66 as bristle was put on the market and took an extraordinary name - "miracle cluster" In October of the same year, DuPont officially announced the birth of the first synthetic fiber in the world, and named PA66 nylon hole nylon snow, which was called nylon in China. Nylon later became "the general name of all polyamides synthesized from coal, air, water or other substances, with wear resistance and flexibility and similar protein chemical structure".
The front pair of nylon stockings made by DuPont participated in the New York World Expo. People described this magical artificial silk stockings as "as thin as spider silk, as strong as steel wire and as beautiful as silk".
On October 24, 1939, DuPont company publicly sold nylon stockings for the first time in the department store where the headquarters is located, requiring each person to buy 3 pairs and provide local address. Therefore, fashionable women from all over the country must first book hotels in the city.
On May 15, 1940, DuPont sold nylon stockings for the first time in the United States. Although each person was limited to one pair, 5 million pairs were sold out on the same day.
Within seven months, nylon stockings brought a profit of $3 million! Many women who couldn't buy them painted lines on their bare legs and pretended to be silk stockings. In a public opinion survey, nylon stockings were what two-thirds of women wanted more. By May 1940, nylon fiber fabrics began to spread all over the United States. Less than two years later, the Pacific War broke out, and nylon immediately disappeared from the civilian market, It is mainly used to produce parachutes, military tents, aircraft tire cord fabrics, military uniforms and other military products. When nylon just returned to the civilian market after the war, beauty loving girls couldn't wait to get home. On the steps at the door of the store, they couldn't wait to put the newly bought nylon silk socks on their legs. This old photo vividly reproduces the scene at that time.
From the beginning of DuPont's basic research without clear application purpose to the birth of nylon, which has changed people's life, the foundation of synthetic fiber industry has been laid in 11 years, with an investment of 22 million US dollars and the efforts of 230 scientists. The invention of nylon has also become a very successful model for enterprises to run basic scientific research. It makes people realize that it is related to technology Compared with science, technology is ahead of production; without scientific research and technical achievements, the development of new products is impossible. Since then, basic scientific research Engaged in or funded by enterprises has sprung up all over the world, making the achievements of basic scientific research more quickly transformed into productivity. Nylon, as a synthetic fiber, has become a blockbuster super fiber Star. In fact, in the year when PA66 was industrialized, DuPont used it to make gears for spinning machinery, but due to poor processing technology, it can not be used on a large scale.
In 1941, Germany processed polyamide with plunger injection molding machine. Due to the limited variety and output, it did not develop much. It was not put into industrial production until after the Second World War.
In 1941, DuPont first developed polyamide molding compounds, which were processed into gears, bearings, wires and cables. By 1948, DuPont had produced 6 kinds and 12 brands of molding products and extruded products. Polyamide has expanded a broad application space as an engineering plastic because of its excellent wear resistance and corrosion resistance, which is used to replace metal in machinery and chemical industry Bearings, gears, pump blades and other parts are manufactured in industries such as, instruments and automobiles. Nylon fiber is to PA plastics as the sun is to stars. The former shines in front of us, so although the latter is equally dazzling, it makes people feel much inferior.
In the decades before World War I and World War II, plastic raw materials gradually changed from coal to oil. People can synthesize thousands of new products from cheap oil, and people's life has become colorful. Natural raw materials can also be used at multiple levels, creating higher economic value. Various plastic varieties have sprung up and realized industrialization, except nylon fiber There are many kinds of PA plastics in the world. During this period, they came out and quickly popularized. The more famous are the following thermoplastic plastics that still produce a lot today.
(1) PS: in 1930, German faben company solved the problems of complex polystyrene process and resin aging discovered by the British in 1911, and began industrial production by bulk polymerization in Ludwigshafen.
(2) PMMA: in 1931, Germany's Roma Haas company first built a factory to produce PMMA, replacing Celluloid as aircraft cockpit cover and windshield.
(3) PVC: as early as 1912, German chemist Fritz klatte He had invented PVC and applied for a patent, but klaette and his greisheim electron company couldn't think of any use for PVC until the patent expired in 1925. However, just a year later, in 1926, the American chemist Waldo Semon Independently invented PVC, and found that this material has excellent water barrier performance and is very suitable for making shower curtains. So Semon and his B.F. Goodrich company applied for a patent for PVC in the United States, so PVC began to be mass produced and applied.
In 1931, the German law company used emulsion polymerization to realize the industrial production of PVC.
In 1933, Simon found that PVC could be processed into soft PVC products by heating and mixing high boiling solvent and Trimethylphenol phosphate with PVC, which made a real breakthrough in the practicability of PVC. British burneman chemical company (Imperial Chemical Company), American United carbon company and gutrich chemical company developed the suspension polymerization of vinyl chloride and the processing and application technology of PVC almost at the same time in 1936. Since then, PVC has been an important plastic variety.
(4) LDPE: in 1933, British burneman chemical industry company found that waxy solids existed on the wall of the polymerization kettle during the test of the reaction between ethylene and benzaldehyde under high pressure, so it invented polyethylene. In 1935, the company also invented the controllable high-pressure polyethylene synthesis method, and began to produce LDPE by high-pressure gas-phase bulk method in 1939.
(5) PTFE: known as the king of plastics, also known as Teflon or fluoroplastics, was first introduced to the market by DuPont in 1943.
During this period, there were not only a variety of plastics, but also a sharp increase in output. The total output of plastics in the world soared from 10000 tons in 1904 to 600000 tons in 1944. One year after Baekeland's death in 1945, the annual output of plastics in the United States alone has exceeded 400000 tons.
The great development of the plastic age -- flowers bloom after World War II
During World War II, the strong demand for synthetic rubber greatly promoted the research progress of petrochemical and polymer materials. Polymer materials mainly refer to synthetic fibers, plastics and synthetic rubber with synthetic resin as raw materials, of which 80% of synthetic resin is used to produce plastics. During the five years from 1946 to 1950 after the war, an average of 27 billion barrels of oil resources were discovered in the Middle East every year, nine times the world's annual oil production at that time.
In the 1960s, the price of oil was $1.50 a barrel. In the 1950s and 1960s, the "four major" purchase heat of cars, televisions, refrigerators and washing machines appeared all over the world. These are inseparable from synthetic materials based on synthetic resin and represented by plastics. Therefore, since this period, the world petrochemical industry has developed rapidly, and the raw materials of synthetic resin have gradually changed from coal tar to petrochemical products. Many key new technologies have been successfully developed in Europe, America and Japan, making more plastic varieties put into industrial production. During this period, the more famous is the invention of Ziegler Natta catalyst, which makes polyolefins (mainly including PE and PP) become plastics with large output in the world, and enables people to design polymer structures according to the requirements of those in need, So as to optimize product performance. Ziegler and Natta also won the Nobel Prize in chemistry in 1963 for this great achievement.
Ziegler, a German chemist, found in 1953 that using alkyl aluminum and titanium tetrachloride as catalysts can produce a polyethylene different from the previous industrialization.
LDPE, which was industrialized in 1939, is made under high pressure. Its molecular structure is like a branch. There are many branches. Therefore, the molecules are arranged irregularly, the density of the material is low, the property is soft, and the melting point is low. It is only suitable for food packaging bags, hoses and other things. The PE molecular structure found by Ziegler is like a thin line without bifurcation. The molecules can be arranged neatly and crystallized. Therefore, it has high density, high melting point and high strength. It can be used to make things with high hardness, such as barrels, bottles, tubes and rods. It is now called HDPE. Ziegler himself did not realize the significance of his invention at that time, and only applied for a patent for ethylene polymerization. Later, Ziegler's work aroused great interest of the Italian chemist Nata. Natta improved the catalyst used by Ziegler to make it suitable for propylene polymerization, and obtained PP with high yield, high crystallinity and high temperature resistance of 150 ℃. This new product is called directional PP. Natta is also an expert in X-ray diffraction structure analysis. His work in this field enables people to deeply understand the relationship between the structure and properties of polymers, which is very important. Since then, people can purposefully design the polymer structure to meet the expected requirements, and the varieties of synthetic materials are more diversified, especially the polyolefin plastic series. By the 1970s, a plastic variety with large output in the world has been formed, and it still ranks first in the output of various plastic varieties, accounting for about one third of the total plastic output.
Once a major breakthrough is made in science and technology, the speed of industrial development will be amazing.
With the advent of nylon and polyester in the 1940s, the output of man-made fiber soon exceeded that of wool at that time. After World War II, especially in the 16 years from 1958 to 1973, the plastic industry developed rapidly driven by rich and cheap petrochemical products. In 1970, the output had reached 30 million tons. In addition to the sharp increase in output, plastic varieties also show the characteristics of a hundred flowers in full bloom: ① a series of varieties are developed from a single large variety through copolymerization or blending modification. For example, in addition to producing a variety of brands, PVC has also developed chlorinated PVC, vinyl chloride vinyl acetate copolymer, vinyl chloride vinylidene chloride copolymer, impact resistant PVC modified by blending or graft copolymerization, etc.
② A series of new varieties of high-performance engineering plastics have been developed. Such as polyoxymethylene POM, polycarbonate PC, ABS resin, polyphenylene ether PPE, polyimide PI, etc.
③ New technologies such as reinforcement, compounding and blending are widely used to give plastics more excellent comprehensive properties and expand the scope of application.
Due to its many advantages such as low cost, light weight, insulation, non-corrosion and non rust, plastics have gradually replaced structural materials such as metal, wood and cement with an amazing increase rate (an increase of 12-15% per year). Its output has exceeded aluminum in the 1950s, and then copper and zinc. It has been close to the output of wood and cement in the 1970s, In the early 1980s, the volume has exceeded the representative of the industrial era - steel. In 1991, the world output of plastic raw materials (resins) exceeded 100 million tons for the first time, and in 2003, it exceeded 200 million tons.
Plastic and life -- love is also plastic, hate is also plastic
The invention of plastic products not only improves the quality of human modern life, but also promotes the progress of human social civilization. All aspects of food, clothing, housing, transportation, communication and entertainment closely related to people's life have formed an indissoluble bond with plastic products, which not only enriches people's life, but also brings convenience and benefits to people, and has become an indispensable part of people's daily life. It can be said that plastic products can be seen where there are people. The per capita annual consumption of plastics in the world was 8kg in 1970, 13.4kg in 1980, 22.5kg in 1995, and more than 50kg in industrialized countries. The countries with large per capita plastic consumption are the United States, Belgium and Germany, which exceeded 150kg in 2001.
Since ancient times, natural fibers such as cotton, hemp, silk and wool have been used as the source of clothing materials, but their production growth rate lags far behind people's demand. The emergence of synthetic fiber makes people find that things in coal and oil can make clothes comparable to natural fibers through chemical reaction. Therefore, synthetic fiber is also called chemical fiber. Chemical fiber and plastic are different forms of products processed from synthetic resin. The vigorous nylon socks revolution not only made nylon widely known, but also promoted more chemical fiber and plastic products to the market. In addition to nylon fiber (nylon), there are polyester fiber, which is well-known as "Dacron", and polyacrylonitrile fiber, which is commonly known as artificial wool, Polypropylene (PP) fiber, which is lipophilic, hydrophobic, strong and durable, polyvinyl alcohol (PVA) fiber, which has good water absorption and is known as synthetic cotton, and polyurethane fiber, which is famous for Lycra. After blending these synthetic fibers with natural fabrics, they can not only maintain the advantages of natural fabrics, but also overcome their disadvantages. Therefore, they have been around the world with natural fibers for only a few decades. Statistics show that in 1996, the world's synthetic fiber output was the same as the world's total cotton, reaching 19 million tons. There are also some synthetic fibers with special properties, such as polyamide (PA) fiber Kevlar launched by DuPont, which can be used to make protective articles such as headgear and armor for battlefield, as well as police bulletproof vests.
PI fiber can withstand high temperature and radiation. Various sole materials are also made of plastics. The well-known wear-resistant soles include polyurethane (PU) plastics and styrene butadiene styrene block copolymer (SBS) plastics. Strong and beautiful PVC, PE, Pu plastic sandals, slippers, rain shoes and miner's shoes have long made straw sandals withdraw from the historical stage. In addition, plastic film shopping bags for easy access to clothes can be seen everywhere. Plastic jewelry is widely used in the decoration of clothes because of its low price and beauty. Women's favorite headflowers are mostly made of acrylate plastic (acrylic) or unsaturated polyester plastic.
The eater is the beginning of all things and the foundation of personnel. There is also a saying that "food is the most important thing for the people", which shows the importance of eating. However, over the past few thousand years, people have been used to the restrictions on the growth of fruits and vegetables in spring, summer, autumn and winter. Food that can not be eaten temporarily can only be preserved by air drying or pickling. With the development of social civilization, the time of food production and the life span of food preservation can be changed by scientific and technological means. Plastics have also made great contributions in this regard. With the plastic greenhouse, we can eat fresh fruits and vegetables all year round; With ABS plastic plate as the inner container of the refrigerator, the food will not rot in hot summer; With PE fresh-keeping film and PP fresh-keeping box, fruits and vegetables are not easy to dehydrate and dry, and food will not taste; With all kinds of plastic tableware resistant to cleaning and high temperature sterilization, we don't have to worry about the fragments of the porcelain bowl scratching our hands; With non-toxic plastic food packaging bags, there will be a wide range of small foods on supermarket shelves; With transparent PET plastic bottles, all kinds of drinks and bottled water give people more choices besides drinking boiled water and fresh fruit juice. Coca Cola once claimed that glass bottles were better packaging materials in the 1970s. Only glass bottles could really maintain the balance between temperature and bubbles. However, the soaring cost of aluminum cans in the 1990s and the recycling of glass bottles made it difficult for Coca Cola to globalize, so plastic bottles were pushed to the front desk. At that time, BusinessWeek listed this as one of the 100 details of globalization. The beer industry calls it a sign of a complete separation from the beverage industry. However, due to the diversification of plastics, beer bottles, an important position of glassware, are also in danger of being lost.
In 1999, Swedes successfully introduced a pen snow plastic beer bottle with excellent barrier performance and UV radiation resistance to the market. At present, pen plastic beer bottles have a firm foothold in the Nordic market. With this kind of unbreakable beer bottle, people can take beer into crowded places such as stadiums and cinemas without worrying that the bottle after drinking will hurt people.
In addition to being used in food packaging, plastics have low density (about 1 / 3 ~ 1 / 2 of natural stone density, about 1 / 2 ~ 2 / 3 of concrete density, only 1 / 8 ~ 1 / 4 of steel density), high specific strength (glass fiber reinforced plastic composite - glass fiber reinforced plastic has higher specific strength than steel and wood), and low thermal conductivity (the thermal conductivity of foam plastics is close to air), acid, alkali, salt, corrosion, insulation, decoration and so on. It also plays an important role in building materials and decoration materials. There are more common plastic doors and windows, pipes, handrails, buckles, floor coils, floor tiles, sanitary ware and foam plastics.
PVC plastic is a versatile plastic building material. Our plastic doors and windows, pipes, handrails, buckles, floor coils, floor tiles and foam plastics are made of PVC. The common pipes for drinking water are non-toxic PE and PP plastic. The popular plastic tap water pipe, PPR water pipe, is a kind of PP plastic. Nowadays, the glass fiber reinforced plastic (commonly known as FRP) sanitary appliances in our kitchen countertops and bathrooms are as white as jade, beautiful and strong. They have gradually replaced ceramic and metal sanitary baths and become the trend of the times.
In the 21st century, people pay attention to fast, convenient and safe travel. Plastic products on all kinds of transportation tools can be seen everywhere. Plastic composite components manufactured by advanced technology have the characteristics of high specific strength, high specific stiffness, beautiful appearance and strong weather resistance. They can not only reduce the weight of transportation tools, but also reduce processing procedures, reduce energy consumption, multi-purpose and improve the quality of transportation The advantages of safety performance and recyclability. In today's global energy shortage, it is of great significance. People's commonly used means of transportation is cars. The amount of plastic used in cars has exceeded 10% of the total weight of cars, and has even reached more than 20% in Europe, America, Japan and other countries. Moreover, the more high-grade cars, the more plastic is used, such as Audi A2 car The total mass of plastic parts has reached 220kg, accounting for 24.6% of the total materials. The vehicle with obvious weight reduction and energy saving effect belongs to the aircraft. According to expert calculation, for each ton of aircraft weight reduction, 300-400 kg of fuel can be saved, so the plastic on the aircraft is a great contributor to reducing costs.
The cockpit cover, windshield and porthole on the aircraft are all polymethylmethacrylate (PMMA) called plexiglass It is made of plastic or PC plastic. The seats and luggage compartments inside the aircraft are made of a variety of plastic alloy products. The tail wing of the U.S. B-777 passenger plane is also made of plastic products. The special plastic peek snow has been used in the engine of the U.S. Boeing aircraft. On the Boeing 787 dream aircraft just launched in July this year, carbon fiber composites Carbon fiber reinforced plastic (CFRP) has replaced aluminum as the main material of the aircraft. The shadow of plastic can also be found on military aircraft and spacecraft.
The airframe of the U.S. F-22 stealth fighter and the main wing and airframe of the Japanese F2 fighter are made of plastic parts. When the spacecraft returns to the earth's atmosphere, due to friction with the air, the surface temperature is as high as more than 5000 degrees. Because it is covered with a special plastic coat with excellent heat insulation effect, only the outer plastic layer is turned into ash at such high temperature The interior of the ship was safe and sound.
Modern life is inseparable from communication, and communication equipment is inseparable from plastic. Any telephone and mobile phone in the world are wrapped in a plastic shell, and any wire, network cable and telephone line are also covered in a plastic coat. Even the glass optical fiber dominating the world has been replaced by plastic optical fiber in short-distance communication. The Internet and TV computers with plastic shell make it easier to watch TV and watch TV The Internet has become an important way of entertainment and leisure for people. People can watch wonderful football matches, enjoy the beautiful natural scenery and understand the colorful world without leaving home. Scientists are still trying to replace the silicon materials inside these electrical appliances with low-cost and soft plastic chips. It is difficult to imagine how TV, computer and Internet could be popularized without plastic. (to be continued...).
