UV glazing has many advantages and broad prospects
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Applying (or spraying, printing) a layer of colorless and transparent paint on the surface of the printed matter. After leveling, drying, calendering and curing, a thin and uniform transparent bright layer is formed on the surface of the printed matter to enhance the smoothness of the surface of the carrier. The glazing process for protecting the finishing and processing functions of printed graphics has become an important means of post-press finishing, and has achieved great results in the packaging processing of foreign trade export products. In the technological innovation of pre-press digital network and multi-color printing, post-press processing can achieve the overall revolution of printing technology only by using high-tech to achieve exquisite automation. At present, due to the unique advantages of UV glazing technology, it has obvious advantages in the development of post-press processing. It is widely used in packaging and decoration, book covers, albums, trademarks, advertisements, calendars, large decorations, posters and other printed materials. The surface finish is processed.
The glazing process can be divided into solvent volatilization glazing, UV glazing (ultraviolet glazing) and heat curing glazing according to the drying method of varnish.
UV glazing advantage
UV glazing is UV curing glazing. It is UV varnish. After being applied to the surface of the printed matter, the UV illuminating varnish can be cured in a short period of time. The basic principle is: under the irradiation of ultraviolet light, the photoinitiator in the UV coating oil absorbs the radiant energy to form a radical or a cation, which initiates the polymerization and crosslinking reaction of the monomer and the prepolymer in a short time. A high molecular polymer solidified into a three-dimensional network structure.
Now with the gradual understanding and mastery of UV glazing technology and the significant reduction in the price of UV coatings, UV glazing technology has been rapidly promoted and applied in the field of packaging and printing with its unique advantages. According to some data, the application of UV glazing technology is growing at a rate of 12-14% per year. It is believed that UV glazing technology will become the main process of post-press processing to increase the added value of products. Compared to other glazing methods, UV glazing has the following advantages:
1. Safe and environmentally friendly.
The UV coating process uses UV coating. The UV coating consists of oligomers, reactive diluents, photoinitiators, photosensitizers and additives. It is 100% solid content, no solvent volatilization factor, and it is safe and non-polluting. Environmental green products. Especially in the era of “green packaging”, the environmental advantages of UV glazing in post-press processing have been well recognized.
2. Not subject to the type of substrate.
3, working at low temperatures, can be used for the printing of heat-sensitive substrates (such as plastic).
4. The product quality is high.
UV coating has fast curing speed, high hardness, good wettability, strong adhesion, and high interferability, wear resistance and gloss value. The surface of the UV-coated product is flat, bright, high-hardness, friction-resistant, scratch-free, and has the advantages of waterproofness and no odor.
5. After the glazing, the substrate can be processed immediately, and has high adaptability in cutting, forming and folding.
6, high efficiency and low cost.
UV wavelength is 200-400nm, it is invisible light, UV light curing uses long-wavelength ultraviolet (UVA) with a wavelength of 316nm. UVA light curing speed is fast, and UV oil can be cured into a uniform coating in 1-2 seconds. The production efficiency is high, and the general drying speed can reach 100-300 m/min. Compared with the glazing calendering process, the equipment covers a small area, and the comprehensive cost of material consumption and energy consumption costs decreases.
UV glazing mode
There are many UV glazing methods, and there are many classification methods. There are mainly the following classification methods:
A. According to the relationship between the glazing machine and the printing machine
According to the relationship between the glazing machine and the printing machine, the glazing can be divided into offline glazing and online glazing. Off-line glazing uses a special glazing machine to glaze the printed matter, that is, printing and glazing are carried out on their respective special equipments. This glazing method is more flexible and convenient, and the equipment investment is small, which is more suitable for professional post-press processing. Used by the manufacturer, but this glazing method increases the transportation transfer between the printing and glazing process, and the production efficiency is low; the online glazing directly connects the glazing unit to the printing machine, that is, printing and glazing on the same machine. On-going, fast speed, high production efficiency, low processing cost, reduced handling of printed products, overcoming all kinds of quality faults caused by dusting, but on-line glazing technology, glazing oil, drying equipment and The requirements for glazing equipment are very high.
B. Press the glazing method
According to the glazing method, the glazing can be divided into roller coating and printing glazing. Roller coating is the most common glazing method. The coating varnish coats the varnish on the surface of the printed product uniformly. The glazing is applied to the printed product through the glazing plate. Partial glazing, commonly used in the gravure glazing, flexographic glazing, offset glazing and screen glazing.
C. Press the glazing product type
According to the type of glazing products, glazing can be divided into full-surface light, partial glazing, matt glazing and artistic glazing. The main function of the full-surface light is to protect the printed matter and improve the surface gloss of the printed matter. The full-surface light is generally applied by roller coating; partial glazing is generally applied to the printed image on the printed matter. The high-gloss picture of the glazing portion is compared with the low-gloss picture without the glazing portion, producing a wonderful artistic effect, the partial glazing is performed by printing glazing; the matt glazing is UV matt oil, and The effect of ordinary glazing is the opposite. It is to reduce the gloss of the printed surface, which produces a special effect. Because the gloss is too high, it has a certain degree of stimulation to the human eye. Therefore, matt glazing is a popular one. Light mode; the role of art glazing is to obtain a special artistic effect on the surface of the glazing product. For example, the use of UV pearl varnish to glaze on the surface of the printed product will produce a pearlescent effect on the surface of the printed product, making the printed product appear noble and elegant. .
Film UV glazing opens up new horizons
UV coating of coated products is a method of printing one or two varnishes in whole or in part after coating the surface of the printed matter to obtain a bright UV varnish layer on the surface of the printed matter. After the film is coated, the UV varnish can enhance the light resistance of the ink and improve the gloss and three-dimensionality of the print. Form a strong contrast. You can use either full glazing or partial glazing.
However, the UV coating of the film product often has the following problems: the first brightness is not good, mainly because the varnish coating is uneven or the varnish is excessively diluted, and the viscosity is too low. At this time, it is necessary to adjust the glazing machine and increase the light. The viscosity of the oil; the second is due to the adhesion of the UV varnish coating is too thick; third, the viscosity of the UV varnish is too small, the coating is too thin will cause the surface of the UV varnish to smear, need to improve the varnish viscosity, Increase the thickness of the coating; the fourth is the phenomenon of white spots and pinholes on the surface of the UV varnish layer. This requires a variety of possible reasons, such as whether the UV varnish coating is too thin and the amount of ethanol diluent added is too high. Whether the dust on the surface of the film is large or so; the fifth problem is that the varnish layer and the graphic are staggered, which is caused by inaccurate overprinting.
Although the UV glazing technology of the film product has appeared in China for a short time, its development speed is very fast, and it has achieved good response and application in both the commercial printing field and the packaging printing field. It can be said that the application prospect of the UV glazing technology of the film product is very broad.