Human production and use of paint have a long history. Generally, it can be divided into three development stages: the use of natural film-forming substances, the formation of the coating industry, and the production of synthetic resin coatings. A large number of archaeological data, such as paintings from the Amitamira Cave in Spain, rock wall paintings from the Lascaux Cave in France, and lacquer patterns on pottery fragments from the Yangshao Culture Period in China, confirm that in the Neolithic Age in 5000 BC, people used the weapons of wild beasts. Oils, grass and tree sap, and natural pigments are used to prepare original painting substances, and feathers, branches, etc. are used for painting.
Starting point: In 1855, the Englishman A. Parks obtained the patent for making paint with nitrocellulose (nitrocellulose) and established the first factory to produce synthetic resin paint. In 1909, American chemist L.H. Baekeland successfully trial-produced alcohol-soluble phenolic resin. Subsequently, German K. Albert successfully researched rosin-modified oil-soluble phenolic resin coatings. After World War I, in order to open up the market for excess nitrocellulose and meet the needs of the development of automobile production, good solvents such as butyl acetate and ethyl acetate were found, and the construction method of air spraying was developed. In 1925, the production of nitrocellulose paint reached its climax. At the same time, phenolic resin coatings are also widely used in the wood furniture industry. In the production of paints, wheel mills are gradually eliminated, and mechanical grinding equipment such as ball mills and three-rollers are promoted and applied in the paint industry.
Breakthrough In 1927, R.H. Keenl of General Electric Company in the United States broke through the alcoholysis technology of vegetable oil and invented the process of preparing alkyd resin using dry oil fatty acids. Alkyd resin coatings rapidly developed into coating varieties. The mainstream of paint got rid of the traditional method of mixing dry oil and natural resin to make paint, and created a new era in the paint industry. By 1940, melamine-formaldehyde resin was combined with alkyd resin to make paint, which further expanded the application scope of alkyd resin coatings and developed into the main variety of decorative coatings, widely used in industrial coatings.
Era of Great Development After the end of World War II, synthetic resin coating varieties developed rapidly. The United States, Britain, the Netherlands (Shell Company), and Switzerland (Ciba Company) first produced epoxy resin in the late 1940s, providing new raw materials for the development of new anti-corrosion coatings and industrial primers. In the early 1950s, polyurethane coatings with a wide range of properties were put into industrial production at the Farben Bayer Company in the Federal Republic of Germany. In 1950, DuPont of the United States developed acrylic resin coatings, which gradually became the main variety of automotive coatings and expanded to light industry, construction and other sectors. After World War II, there was a surplus of styrene-butadiene latex, and the United States actively researched using styrene-butadiene latex to make water-based latex paints. In the 1950s and 1960s, polyvinyl acetate latex and acrylic latex coatings were developed, which are the largest varieties of architectural coatings. In 1952, the Federal German company Knasak Grisain invented vinyl resin thermoplastic powder coating. Shell Chemical Company developed epoxy powder coatings. The Ford Motor Company of the United States developed electrodeposition coatings in 1961 and implemented industrial production. In addition, in 1968, Bayer Farben of the Federal Republic of Germany was the first to sell light-cured wood paint on the market. Latex coatings, water-soluble coatings, powder coatings and light-curing coatings have significantly reduced the amount of organic solvents in coating products, or even eliminate the use of organic solvents, opening up a new field of low-pollution coatings. With the development of electronic technology and aerospace technology, elemental organic resin coatings, mainly silicone resin, developed rapidly in the 1950s and 1960s and occupied an important position in the field of high-temperature resistant coatings. During this period, heterocyclic resin coatings, rubber coatings, vinyl resin coatings, polyester coatings, inorganic polymer coatings and other varieties were developed and realized industrial production.
With the development of synthetic resin coatings, large-scale resin reactors (see kettle reactors) are gradually adopted, and efficient grinding equipment, such as high-speed dispersers and sand mills, are gradually used in the grinding process. Used to replace the three-roller mill of the 1940s and 1950s.
In order to cooperate with the promotion and application of synthetic resin coatings, coating technology has also undergone fundamental changes. In the 1950s, high-pressure airless spraying was promoted in the shipbuilding industry and steel bridge construction, greatly improving the efficiency of painting.
Electrostatic spraying was developed in the 1960s. It is suitable for large-scale assembly line painting and promotes the further promotion of powder coatings. Electrodeposition coating technology was developed in the 1960s to adapt to the emergence of water-soluble coatings. Especially after ultrafiltration technology solved the wastewater problem of electrodeposition coating, it further expanded its application areas
New stage Since 1973, due to the impact of the oil crisis, the coating industry has developed in the direction of saving resources and energy, reducing pollution, conducive to ecological balance and improving economic benefits. The development of high-solid coatings, water-based coatings and powder coatings, as well as the development of low-energy-consumption curing varieties such as radiation-curing coatings, are its specific manifestations. In 1976, a new type of electrodeposition coating, cathodic electrodeposition coating, developed by the Pittsburgh Flat Glass Industry Company in the United States, improved the anti-corrosion capabilities of automobile bodies and was rapidly promoted. In the 1970s, organic-inorganic polymer emulsions were developed and used in architectural coatings and other fields. Functional coatings (see coatings) became a research topic in the coatings industry in the 1970s, and a series of new varieties were launched. In the 1980s, various architectural coatings developed rapidly. Electronic computers have been used in paint production, testing, and management. Robots (manipulators) have been widely used in special or dangerous situations to replace manual painting. This stage has the following characteristics: ① Guided by modern scientific theories, research and development work is carried out purposefully, which accelerates the development process. For example: the theory of modern chemistry is applied in the coating industry, and coating additives are widely promoted and used. As a result, the product performance and production efficiency of the coating industry have been greatly improved. ②Using polymerization, modification and mixing methods, the variety of synthetic resins with characteristics is increasing, improving the performance of coatings, and increasing the variety of functional coatings. ③ The testing of coating quality has shifted from measuring surface phenomena to measuring the intrinsic quality of coatings. For example, more emphasis is placed on measuring the molecular weight and molecular weight distribution of synthetic resins to understand the quality of synthetic resins, and using scanning electron microscopy to observe the microstructure of coating films to guide products. of production.