Polyester paint (code Z) is a paint with polyester resin as the main film-forming substance. Polyester resin is formed by polycondensation of polybasic acid and polyol. It is divided into bonds.
Unsaturated polyester resin is a linear polymer prepared by reacting unsaturated dibasic acid (such as maleic anhydride or fumaric anhydride) and diol (such as ethylene glycol, internal glycol). Containing unsaturated groups, such as CH2=CH-CH2 one, one CH=CH one and so on. The mixture of this kind of linear polyester resin and certain monomers (such as styrene , acrylate, vinyl acetate, triallyl cyanurate, etc.), in the presence of initiators and accelerators, can be cured at room temperature. It becomes an insoluble substance, and copolymerizes and solidifies to form a film.
A series of different polymers can be obtained by changing the types and relative dosages of various alcohols and acids . The coating industry uses this resin to make solvent-free unsaturated polyester resin coatings. In the unsaturated polyester resin paint, add some photosensitive substances or directly polymerize the photosensitive substances with unsaturated polyester resin to make photopolymerizable paint. The advantage of photopolymerization paint is that it can be completely cured in a short time, it is convenient to store, and it can use a one-component system, and the loss of styrene monomer is very small during curing. It can be coated on plywood , plastic, paper and other materials. As a solvent-free coating, unsaturated polyester resin paint has been widely used in various fields, such as coatings for chemical storage tanks and wood coatings. Unsaturated polyester is also the raw material of polyester FRP.
Unsaturated polyester coatings have good color, high film hardness, wear resistance, gloss retention, good color retention, certain heat resistance, weather resistance and temperature denaturation resistance, and resistance to weak acids, weak bases and solvents . , can be cured by heat or at room temperature, no solvent volatilization, and can be painted into a thicker coating at one time. Its disadvantages are multi-component packaging, inconvenient use, general adhesion on metal, brittle coating film, poor storage stability of coating, and limited use. The most used are unsaturated polyester varnish, enamel and putty. Varnish is mainly used for high-grade woodware (such as pianos, furniture), room wood decoration and surface decoration of cars, bicycles, sewing machines, electric fans, instruments, hardware, plastics, toys, etc. with high decorative requirements .
Saturated polyester resin is made of phthalic acid and diols, long-chain diols, etc. Saturated polyester resin paint, also known as oil-free alkyd paint, generally uses melamine resin as a crosslinking agent to make polyester baking paint, which is cured by baking. Saturated polyester paint film is tough, wear-resistant and heat-resistant, and is suitable for enameled wire baking varnish and dip-coating insulating baking varnish for motors, transformers , and electrical coil windings.
