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Basic composition of paint

Coatings are generally composed of film-forming materials, pigments, additives, solvents, diluents, etc.

After the construction of the coating, with the evaporation of the solvent and the diluent, the film-forming material is dried and formed into a film. The film-forming material can be formed separately, or it can be bonded to the pigment and other substances to form a film together, so it is also called a binder, which is the basis of the coating.

Early applications were mainly oil and natural resins. With the development of petroleum industry, synthetic resin has replaced oil and natural resin widely used in coating industry. The main application of synthetic resin mainly includes acrylic resin, alkyd resin, polyurethane resin, epoxy resin, amino resin, silicone resin, fluorocarbon resin and so on. The choice of coating resin is mainly based on the structure and performance of the resin, the nature of the substrate, the use of the environment, the construction environment, cost and other factors.

Basic characteristics of resin

acrylic resin

Acrylic resins refer to polymers obtained by homopolymerization or copolymerization of acrylate monomers, including thermoplastic and thermosetting acrylic resins. The characteristics are as follows: light color and high transparency of the paint film; Good light resistance, weather resistance, not easy to yellowing, and good outdoor exposure durability; Thermoplastic resin is easy to use, wide in temperature range and good in drying. Thermosetting resin has better gloss, hardness and chemical resistance after crosslinking with curing agent. For example, two-component polyurethane coating matched with isocyanate curing agent and high-temperature baking coating matched with amino resin; So far, the most successful class of water-based varieties. Water-based one-component acrylic emulsion, water-based two-component hydroxyacrylic emulsion, water-based two-component hydroxyacrylic dispersion and other types of products are widely used in a variety of fields.

alkyd resin

Alkyd resin refers to a modified polyester resin prepared from a polyhydric alcohol, a polybasic acid and a vegetable oil. The characteristics are as follows: low cost and simple process; Low requirements for environmental substrates; High gloss, good fullness and bright color paint; Good hardness and good adhesion; General weather resistance, poor gloss retention and durable volatile light pulverization; Relatively poor drying and low initial hardness; Water-based direction is mainly water-soluble, with slightly less environmental protection.

polyurethane resin

Polymeric compounds containing urethane repeating segments in the molecular structure are called polyurethane resins. Polyurethane resins are formed by polymerization of polyols and polyisocyanates, so there are many types and strong adjustability. Common characteristics are: good adhesion, high strength and good wear resistance; Stretching resistance and excellent flexibility; Good water and solvent resistance; Wide curing temperature range, curing at high and low temperatures; Excellent high temperature and low temperature performance; Good decoration and protection; Aliphatic polyisocyanate has excellent weather resistance; Higher price; Polyurethane resin containing hydroxyl or carboxyl group can be configured with isocyanate curing agent in two components.

Epoxy Resin

Epoxy resin refers to a polymer prepolymer containing two or more epoxy groups. Taking bisphenol A epoxy resin coating as an example, the characteristics are as follows: high crosslinking density and high hardness; Excellent water resistance, chemical resistance, especially alkali resistance; Good adhesion to various substrates and high bonding strength; Low curing shrinkage rate,<2%; Excellent electrical insulation; Poor weather resistance, degradation under ultraviolet radiation; The cured product is brittle, low impact strength, and not too high temperature resistant.
silicone resin

Silicone resin is a cross-linked semi-inorganic polymer with Si-O-Si as the main chain and organic groups on the silicon atoms. It not only has some characteristics of inorganic matter, but also has some properties of organic matter. Excellent weather resistance, not easy to yellowing under ultraviolet radiation; good water resistance, excellent high temperature resistance; excellent electrical insulation, stable dielectric properties in a wide range of temperature, humidity and frequency; moisture-proof, anti-mold, radiation resistance, oxidation resistance characteristics; separate use of paint film is too soft, commonly used acrylic resin, alkyd resin, polyurethane resin, epoxy resin, etc. are modified to improve the hardness and drying degree of the paint film. Silicone resin is mainly to give the paint film color retention, weather resistance; widely used in motor equipment coil dipping varnish, insulating paint, heat-resistant, weather-resistant anti-corrosion coatings, moisture-proof coatings, radiation-proof coatings.
fluorocarbon resin

The fluorocarbon resin refers to a resin synthesized by polymerization of a fluoroolefin or copolymerization of a fluoroolefin and another monomer. Due to the large bond energy of the C- F bond, the coating is endowed with extremely high chemical stability. Good corrosion resistance and chemical resistance; excellent weather resistance, can withstand high-intensity ultraviolet radiation; good thermal stability; excellent electrical properties and flame retardant properties; mainly used in heavy-duty anti-corrosion fields, such as marine anti-corrosion, bridge anti-corrosion, construction, etc.