The chemical composition of uv coating mainly includes radiation prepolymer, thinner and photoinitiator:

1. Radiation Prepolymers Prepolymers are chemical systems with residual unsaturation molecules. This molecule is capable of cross-linking with other unsaturated molecules when in certain conditions, from a liquid to a solid coating. It is required that these unsaturated molecules must be stable and not react with each other before crosslinking.
Prepolymer type:
1) Epoxy acrylate;
2) Acrylated oil;
3) Acrylic urethane;
4) unsaturated polyester;
5) Polyester acrylate;
6) Polyether acrylate and the like.

2. Diluent diluents are also chemical systems containing unsaturated molecules. Use it to adjust the viscosity, while it is a film-forming substance. Some situations can replace prepolymers. To make the viscosity reach the desired range, it is often necessary to add a small amount of volatile organic solvent to the mixture of prepolymer and diluent, but up to no more than 5%-10%.
Diluents are divided into active and inactive two. Inactive diluents include solvents and plasticizers. Solvents are mainly volatiles. Plasticizers impart certain flexibility to the cured coating, which not only reduces viscosity but also facilitates coating and leveling. The addition of a reactive diluent to the prepolymer can change the viscosity, tackiness, flexibility and hardness. Reactive diluents can be divided into monofunctional and polyfunctional groups.
Monofunctional reactive diluents, such as 2-ethylethyl acrylate, are flammable, volatile, and irritating to the skin. The polyfunctional reactive diluents have low volatility, high flash point, and low skin irritation.
The role of reactive diluents is as follows:
1 Adjust viscosity and leveling
2 and the photoinitiator system determines the curing speed;
3 with high molecular weight prepolymer molecules linked together to accelerate curing;
4 Improve and improve the performance of cured coatings.

3. Photoinitiator A photoinitiator is defined as a molecule that absorbs radiant energy and chemically changes to produce an active intermediate that has the ability to initiate polymerization.
The photoinitiator does not participate in the curing, so the photoinitiator concentration is low, and the amount thereof requires that the initiator itself or its photochemical product must not adversely affect the chemical and physical properties of the polymer after curing. Benzophenones are usually used.
Photoinitiators In the process of initiating polymerization, two more substances are indispensable. Photosensitive type refers to a chemical reaction that transfers energy to a photoinitiator molecule to initiate polymerization after absorbing light energy, and the photosensitizer recovers to its initial inactive state. The other is called photoactive agent or photo-enhancer (usually amines). It mainly enhances the activation rate of photoinitiator. It does not absorb radiation by itself and does not initiate polymerization, but it can increase the curing rate.