1. Polyurethane two-component resin synthetic coatings (PU)
Polyurethane two-component resin synthetic lacquer is the abbreviation of polyurethane paint. It is composed of polyisocyanates and polyhydroxyl compounds. It is a continuous membrane surface with polyurethane as the main film forming material. It is one of the main varieties of wood finishing varnish at home and abroad.
PU two-component coatings, a group containing polyisocyanate (---NCO) oligomers (or adduct), used as curing agents. The second component is polyhydroxyl (---OH) compound or tree, pigments, fillers, solvents, catalysts and other additives. A mixture of a and B two components and PU diluent is mixed proportionally and applied to the surface of the object, that is, the cross-linking reaction of ---OH and ---NCO occurs. The resin is solidified from the small molecule into a three-dimensional network macromolecule.
The film forming process of PU two-component coatings is a chemical reaction process of proportionate mixture of a and B two components. Therefore, in practical operation, it is not possible to increase or decrease the dosage of curing agent at any time to meet certain needs or solve problems in painting. Increasing the curing dose will make the paint film crisp, easy to pin holes, bubbles, and reduce adhesion. Reducing the dosage will make the film soft, dry, hard enough and scratch resistant.
The advantages of PU paint are as follows:
A, good anticorrosive properties, paint film heat resistance, water, chemicals, solvents, acid and alkali, generally in 40 - 120 - C can be used normally.
B, has good physical and mechanical properties, hard and wear-resistant, fullness, high gloss, good flexibility, with high decorative effect.
C, good adhesion to various surfaces, can react with OH containing wood fibers, effectively seal wood and have strong adhesion.
D, high solid content (50----70%), high construction efficiency, low coating cost and wide application range (the national furniture industry 60% uses PU coating).
A, the construction environment is high, sensitive to water, paint film damage is not easy to repair;
B, two components blending is inconvenient, the ratio is strict, and the use time after paint is limited (the activation period is limited).
C, multiple times of spraying and grinding, slow drying speed and long construction period.
2, unsaturated polyester coatings (PE)
Unsaturated polyester paint is a straight chain polyester resin made from unsaturated two membered ester and diol, and then it is made up of monomer diluent and related auxiliaries. In the presence of initiator (white water) and accelerant (blue water), the coating can be crosslinked into insoluble film. Unsaturated polyester lacquer is a three component coating, that is, the paint component composed of tree ester filler and auxiliaries, and the curing agent composition composed of initiator and its excipient, and also a thinner (usually unsaturated monomer, such as styrene), which takes part in cross-linking reaction and acts as a film forming agent. Thinner is not only solvent but also film-forming material in unsaturated polyester paint.
The main film forming material of PE paint:
A, main agent: unsaturated polyester resin
B, LAN Shui: accelerant, activator, with strong reducibility, can form redox initiating system with peroxide, enhance the initiation effect of polyester resin, and make the resin crosslinked at room temperature or lower temperature. The performance of blue water is relatively stable, and it is not easy to fail.
C, Whitewater: initiators, usually all kinds of peroxy compounds and hydrogen peroxide compounds, play a role in initiating polymerization in paint and promoting the curing and crosslinking of polyester. White water is unstable, flammable and explosive, and should be kept away from light and low temperature. Otherwise, it will be invalid if the time is longer.
D and diluent: unsaturated monomers are both crosslinking agents and solvents. The most commonly used styrene is styrene.
The advantages and disadvantages of PE paint are compared.
A, not easy to hang and blister, can be thickly coated at a time, saving labor and time.
B, high solid content (close to 100%), high hardness and good fullness.
C, solvent free, no toxic or harmful gas release, no pollution to the environment.
D, film heat resistance, chemical resistance is strong, especially suitable for tea tables, conference tables, tables and other guest rooms, restaurant furniture surface finishing.
A, strong smell and strong irritation.
B is brittle and difficult to polish.
C, multi component allocation is inconvenient and the activation period is short.
D, high risk of construction.
Attention should be paid to the construction of PE lacquer mixture.
A, lanshui and white water must be placed separately (to prevent direct mixing of blue and white water and explosion).
B, do not mix blue and white water at the same time, otherwise easy to fire. When painting, the main ingredients should be divided into two parts, one is garland water, the other is mixed with white water, and then the mixture is mixed 1/2 times before spraying.
It is not suitable to paint too much at a time. On the basis of the ratio of white water on the packaging pot, the amount of blue and white water can be increased or reduced according to the environment and climate (temperature and humidity). When the blue water is added for a long time, the paint is green and black, affecting its transparency. When white water is added, the activation time is short, the paint film is crisp, adhesion, flexibility is not good, and it is easy to peel off.