The principle of UV curing and the selection of light source systemread count [750] release time：2019-12-20 21:31:00
UV curing Principle and selection of light source system UV curing It is a photochemical reaction. The principle is that there is no solvent volatilization. A photoinitiator or photosensitizer is added to a specially formulated resin. After absorbing the high-intensity ultraviolet light in the ultraviolet light curing equipment, active free radicals or ionic radicals are generated, which triggers polymerization, cross-linking and grafting reactions, converting UV coatings, inks, adhesives, etc. from liquid to solid in a short period of time. Call it curing. The curing device consists of a light source system, a ventilation system, a control system, and a box. The light source system consists of UV lamp tubes, lampshades, transformers, and capacitors.
1. Selection of UV lamp power in the light source system. The lamp power is the radiant energy of UV light. It must first meet the spectral wavelength and power density requirements of UV ink absorption. If the UV lamp power is not enough, no matter how long the illumination time is or how many times it passes through the UV curing device, the complete curing of the product will not be achieved. On the contrary, it will also make the surface layer of UV ink become brittle, aged, and blocked, and the ink adhesion will also be poor, which will make the interlayer bonding force of overprinting worse. This is because the light of the low-power UV lamp cannot penetrate the bottom of the ink layer, and the bottom is not cured or the curing is not sufficient. Generally, the maximum service life of a high-pressure mercury lamp is 800-1000 hours. It should be replaced after the time is reached, because the intensity of the ultraviolet light emitted by the UV lamp gradually becomes weaker, which will affect the curing effect. UV lamp intensity and power generally meet the requirements of 80-120W/cm2, and the power must be selected according to the cured product and curing speed. Because the greater the power, the greater the heat. The intensity of the UV lamp depends on the power density of the UV lamp tube. Common specifications are: 200W/inch, 300W/inch, 400W/inch, and 600W/inch.
2. Reflectors include non-focused, focused and multi-faceted reflective types. Focused type is generally used. The structural feature is that the reflected UV light energy is concentrated and the light curing efficiency is high, which is beneficial to the ink curing of thick ink layers and can completely solidify the deep layers of the ink.
3|. The selection of the transformer must match the power of the UV lamp. The transformer must have sufficient output voltage to ensure that the UV lamp can work at full power. If the output voltage is too high, the lamp will burn out; if the output voltage is too low, the lamp will not be able to operate at full power, resulting in insufficient intensity of ultraviolet output.
4. The capacitor must be matched with the lamp and transformer, and the voltage resistance of the capacitor to be used should be selected according to the voltage output by the transformer. Improper selection will cause capacitor breakdown, thus affecting the normal operation of the UV curing device. UV energy meter LS120 is used to analyze the UV intensity distribution and temperature distribution at various points during the curing process, which facilitates process analysis and formulation of process parameters during the production process.
