UV curing (UV) coating is a new type of environmental friendly coating. Its drying rate is very fast. It can be cured by UV light in a few seconds, and the production efficiency is high.
UV curing coatings are mainly composed of oligomers, active diluents, photoinitiators and additives.
1. Oligomer
Film forming material is the main component of coating, which is the fluid component of coating. The film performance, construction performance and other special properties of the coating mainly depend on the film-forming material. The film-forming material of UV coating is oligomer, and its performance basically determines the construction performance and light curing rate of the coating before curing, the film performance after curing and other special properties.
UV coatings are mainly free radical light curing systems, so the oligomers used are all kinds of acrylic resins. Cationic UV coating oligomers are epoxy resin and vinyl ether compounds.
2.Active diluent
Active diluent is another important component of UV coating. It can dilute and reduce viscosity, and also has the property of adjusting the curing film. Acrylate functional monomers have high reactivity and low volatility, so they are widely used in UV coatings. Acrylic esters are commonly used as active diluents for UV coatings. In the actual formula, mono -, bifunctional and multi-functional acrylates will be used together to make their properties complementary and achieve the purpose of good comprehensive effect.
3. Photoinitiator
Photoinitiator is a special catalyst in UV coatings. It is an important component of UV coatings and determines the UV curing rate of UV coatings.
For colorless varnish UV coatings, 1173, 184, 651 and bp/ tertiary amine are often used as photoinitiators. 184 with high activity, low odor and yellowing resistance, it is the preferred photoinitiator for yellowing resistant UV coatings. In order to improve the light curing rate, it is often used in combination with TPO.
For colored UV coatings, photoinitiators should be itx, 907, 369, TPO, 819, etc. Sometimes, in order to reduce oxygen polymerization inhibition and improve the UV curing rate, a small amount of reactive amine is often added into UV coatings.
4. Additives
Additives are the auxiliary components of UV coatings. The role of additives is to improve the processing performance, storage performance and construction performance of the coating, improve the film performance and endow the film with some special functions. Commonly used additives for UV coatings include defoamer, leveling agent, wetting dispersant, adhesion promoter, matting agent, polymerization inhibitor, etc., which play different roles in UV coatings.
Post time: Jul-05-2022