Analysis on the influencing factors of the hottest

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Analysis of influencing factors of UV printing quality III

III Discussion on UV light source

generally speaking, those printed with UV ink are generally referred to as UV printing. The main principle of UV printing is UV radiation, and the radiation line is a type of electromagnetic wave. Different radiation energy is distinguished by different wavelengths. The wavelengths of different energy form the electromagnetic spectrum. According to the length of the wavelength, they are divided into the following types (from short to long): cosmic ray, gamma ray X-ray, ultraviolet, visible spectrum, infrared, microwave and radio wave, etc

as mentioned in the preface, the electromagnetic spectrum is divided into (from short to long) cosmic ray, gamma ray, X-ray, ultraviolet, visible spectrum, infrared, microwave and radio wave according to the length of the wavelength. Among them, ultraviolet is defined by the International Commission on illumination. According to the length of the wavelength, it can be divided into three kinds: respectively:

(I) uva:

that is, ultraviolet with a wavelength within the electromagnetic spectrum range of 315~400mm, It is the most harmless and common ultraviolet ray, because it has the smallest energy. It is cross called Blacklight, that is, near ultraviolet ray. It is usually used in relatively harmless and make fluorescent substances emit ultraviolet light. Because it is also called photochemical line, it represents the energy output that can produce the maximum polymerization hardening efficiency when UV ink is used, and this point is usually used to measure whether the UV light source has been attenuated. This point is an important reference point for measurement

(II) uvb:

refers to ultraviolet light with wavelength in the electromagnetic spectrum range of 280~315mm, which is the most typical destructive ultraviolet light. Because it has enough energy to damage biological tissue, it will cause skin cancer. Because the ozone layer has been destroyed recently, it is very important to reduce the time of exposure to sunlight. This wavelength does not play an effective role in UV ink printing, so unless there is a special need, the energy distribution of UV lamps generally used in UV printing in this area is less valued

(III) uvc:

that is, ultraviolet light with wavelength in the electromagnetic spectrum range of 100~280mm, and short wavelength UVC are almost completely absorbed in the air. In terms of the use of UV printing, it has the effect of strengthening the hardening of the surface of the ink film. In recent years, there is a method of UV printing by blowing the surface of the printed matter with nitrogen. Its purpose is to reduce the chance of UVC producing ozone, and make the radiant energy in UVC can be fully used for polymer hardening and curing drying. Although this method is more cost-effective, it improves the efficiency of polymer hardening and drying to the best level

IV The introduction of UV ink BS EN 1364 ⑴: 1999 wall introduction

while UV ink is made by using a certain wavelength of UV radiation and through instantaneous photochemical reaction polymerization and curing (ultra violet curing). Its hardening speed can be adjusted by the type and amount of photoinitiator, the intensity of UV lamp, the speed of drying and the number of UV lamp. It is precisely because of the requirements of the longitudinal load and transverse load borne by the UV lock: line radiation, UV ink has the characteristics of rapid line drying, and this UV characteristic enables it to be printed on non paper, such as PVC (polyvinyl chloride), pet (polyethylene terephthalate), synthetic paper... Etc., and because it can be quickly line drying, reprocessing or reverse reprinting can be done without waiting, Therefore, there is no need to spray powder when drying. Even if printed on paper, it has higher gloss and friction resistance

the advantages and disadvantages of UV printing are shown in [table 4]

advantages and disadvantages 1 No volatile matter and powder spraying problem 1 The price of raw materials and equipment is too high 2 Can improve the quality of finished products 2 The cost of drying equipment is too high 3 Increase the output of products 3 Better ventilation equipment is required 4 Reduce the demand for production space 5 Low energy demand

UV inks are mainly composed of pigments, quasi polymers, monomers, photoinitiators, sensitizers and fillers. The structural differences between UV inks and conventional oxidation inks are shown in Table 5

composition and structure of ink UV ink traditional oxidized ink pigment quasi high polymer versicolor monomer solvent light coincidence starter (sensitizer) desiccant additives additives

improve resource utilization table 5 composition and structure comparison table of UV ink and traditional oxidized ink

from table 5, it can be clearly seen that the corresponding composition and function between UV ink and traditional ink are similar, Its chemical composition and structure are completely different

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