UV glazing materials and process indicators (1)

In recent years, uv (ultraviolet) glazing technology is gaining popularity in the printing field. So what is uv? What is the use of uv for printing? What are the benefits of using uv technology for printing? and many more. Below we take these problems to get closer to uv.

Uv is the abbreviation of Ultraviolet Ultraviolet in English. Ultraviolet light is a band in the electromagnetic spectrum. Waves with a wavelength of 100 nm to 400 nm are called ultraviolet rays. The uv that we generally say in printing is actually the abbreviation of ultraviolet curing, that is, the process that the printed matter is dried under ultraviolet irradiation after the printing is finished.

First, the advantages and disadvantages of uv polishing:

advantage

1 There is no solvent in the formula, so there is no problem caused by solvent evaporation;

2 Fast curing at room temperature;

3 Reduce energy consumption. Curing speed, so that the required energy per unit area decreases;

4 can be coated with heat sensitive substrate;

5 The coating process is simple and easy;

6 Save space, much shorter than infrared heat drying oven;

7 Finished products can be stacked immediately;

8 Excellent coating performance.

Shortcomings

1 If you do not use harmful monomers, it is often difficult to prepare coatings with very low viscosity;

2 expensive;

3 has skin irritation;

4 uv light source will produce ozone;

5 The coating has low adhesion and shrinkage.

Second, the chemical composition of uv coating oil.

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 The diluent is also a chemical system 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. (To be continued)