What is the role of waterborne polyurethane in coatings?

Update:Let's talk about the role of resin in coatings, for example1. The role of alkyd resin2. The role of acrylic resin3. The ...
Let's talk about the role of resin in coatings, for example
1. The role of alkyd resin
2. The role of acrylic resin
3. The role of amino resin
4. The role of epoxy resin
5. The role of polyurethane resin

1. Bisphenol A epoxy resin cured product has good chemical resistance, especially alkali resistance; excellent adhesion to various substrates, high bonding strength, wide bonding surface; curing High mechanical strength, excellent electrical insulation, excellent hardness and excellent water resistance, can be used as structural materials; low curing shrinkage, less than 2%, is a coating with the smallest shrinkage in thermosetting plastics. However, the weather resistance is poor, and it will degrade under ultraviolet light irradiation, resulting in a decline in performance, which limits its outdoor use, and the cured product is brittle, has low impact strength, and is not very resistant to high temperature.

2. Polyurethane coating has a wide curing temperature range and can be cured under high and low temperature conditions. The formed paint film has strong adhesion, good wear resistance, high and low temperature resistance, and has good decorative and protective properties. Therefore, Widely used for decoration and protection of furniture, automobiles, airplanes, steel equipment, etc.

3. Long oil alkyd resins are mainly used as architectural coatings, medium oil alkyd resins are mainly used for air-drying industrial coatings, and can also be used as refinish paints for automobiles, trucks and heavy goods vehicles, and short oil alkyd resins are mainly used for amino and amino Resin is used as an industrial drying topcoat such as metal furniture coatings, bicycles, radiators, etc.

4. The coatings prepared from acrylic resins have the characteristics of light color, high transparency, light resistance, weather resistance, good outdoor exposure durability, such coatings are not easy to decompose or turn yellow under ultraviolet radiation, and have a wide range of operating temperatures.
In fact, the role of resin in coatings is the same, that is, as a film-forming substance, it is a carrier for pigment filler additives. Alkyd resin is cheap, acrylic resin is good, amino is generally used as a curing agent for thermosetting resin, epoxy resin Resin has good adhesion to metal, good resistance to salt spray, etc. Polyurethane resin seems to be mostly water-based.