Uv glazing materials and process indicators (2)

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. Photoinitiators are defined as molecules that absorb radiant energy and undergo chemical changes to produce reactive intermediates that have 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.

Third, uv coating the chemical process.

The basic composition of photo-curing materials are prepolymers, diluents, photoinitiators, auxiliaries, and pigments. The curing chemical process of light is excited by the absorption of photon energy by photoinitiators to form free radicals, which initiate polymerization of the prepolymer and the diluent (initiate molecular chain growth).

Fourth, the uv light oil on the surface of the print process:

1. In addition to powder on the general printing machine has a powder removal device, when the printing ink color is large, commonly used dusting to solve the dirty problem. However, the dusting glue sticks to the surface of the ink like sandpaper. After applying uv light oil, there is no gloss. Therefore need to remove powder. Removal method: First use a brush to sweep, the direction of the brush's rolling is opposite to the direction of the paper's movement; the powder is swept and then sucked into the outdoor through the suction duct. When the powder and the ink are mixed together into a granular form and cannot be cleaned, two light rollers can be used to press the surface of the paper to flatten the powder particles.

2. Corona treatment Some printing materials, such as pp or pet, have poor affinity for uv gloss oil. Some inks contain wax and many are not affluent to uv oil. The use of high-voltage discharge treatment to improve affinity can be achieved. Evenly adhered to uv oil.

3. Bottom oil on the oil seepage paper should be first on the white base oil, the paper seal the pores, improve whiteness, and then on the best uv oil. Such as the surface coating layer of thin white paper, if painted directly uv Varnish. The oil will quickly penetrate into the bottom layer and will not shine. Instead, it will reflect the bottom ash color and make the paper surface blue after glazing. If you first hit a layer of bottom, then apply uv oil to solve this problem. Base oils are generally hot dry type.

4.uv coating uv varnish.

5. Cool the fan through the uv cured print to reduce the surface temperature. One purpose is to avoid paper deformation and the other is to prevent post-curing from continuing. (To be continued)