How is product technology iteration divided in this sub-paint?

The first generation of lacquer is natural lacquer, which is made of raw lacquer collected by sumac trees and tung oil and rosin. It is a natural coating product. The molecular structure of urushiol, the main film-forming substance, contains both aromatic hydrocarbons and aliphatic long side chains, so urushiol has dual characteristics of aromatic and aliphatic. Urushiol polymer was formed under the catalytic oxidation of laccase, and the long side chain was oxidized and polymerized to form a three-dimensional network structure. Therefore, it has excellent physical and chemical properties. Poor flexibility and brittleness; The impact resistance is poor, only 30cm;; The alkali resistance of paint film is poor; In addition, the weather resistance is poor, and it is easy to lose light, crack and age under sunlight, because ultraviolet rays will break the carbon bond of urushiol and degrade the polymer structure.

The second generation of natural coatings industrial production era. Its landmark event was 1773, and the British Witting Company collected and published the formula of refining varnish with natural resin and drying oil. 1790, the first paint factory was established in Britain. In the early production of colored paints in the coating industry, the pigments were transferred to drying oil, and then mixed and diluted to a suitable viscosity during construction; /kloc-in the mid-9th century, the factory directly prepared the coating suitable for construction, namely ready mixed paint. From then on. The coating preparation and production process are completely controlled by the coating factory, which promotes the development of large-scale production.

The third generation is the era of synthetic resin paint. /kloc-in the middle of the 0/9th century, synthetic resin appeared, and the film-forming materials changed, entering the period of synthetic resin paint. 1855, an Englishman, A. Parks, obtained the patent of nitrocellulose (nitrocellulose) coating and established the first synthetic resin coating factory. 1909, American chemist L.H. Baekeland successfully trial-produced alcohol-soluble phenolic resin. Subsequently, K. Albert, a German, successfully studied rosin modified oil-soluble phenolic resin coatings. ...

The fourth generation is the era of two-component products of synthetic resin. Its landmark event was that the United States, Britain, the Netherlands (Shell Company) and Switzerland (Ciba Company) first produced epoxy resin in the late 1940s, which provided new raw materials for the development of new anticorrosive coatings and industrial primers. Later, in the early 1950s, Faben Bayer Company of the Federal Republic of Germany put polyurethane coatings with various properties into industrial production.

The fifth generation is the era of environmental protection paint. The coating industry is developing in the direction of saving resources and energy, reducing pollution, benefiting ecological balance and improving economic benefits, mainly including water-based coatings, powder coatings and solvent-free coatings with high solid content. This stage has the following characteristics: ① under the guidance of scientific theory, research and development work is carried out purposefully, which accelerates the development process; (2) With the methods of * * * polymerization, modification and mixing, the varieties of characteristic synthetic resins are increasing, the performance of coatings is improved, and the varieties of functional coatings are increasing; ③ The detection of coating quality has changed from measuring surface phenomenon to measuring internal quality of coating.