Advantages and methods of UV curing glazing

A preliminary study on the advantages and methods of UV curing glazing

painting (or spraying, printing) a layer of colorless and transparent paint on the surface of the printed matter, forming a thin and uniform transparent bright layer on the surface of the printed matter after leveling, drying, calendering and curing, which plays a role in enhancing the surface smoothness of the carrier and protecting the finishing processing function of printed pictures and texts, and has become an important means of post press finishing, Great achievements have been made in the packaging and processing of export products. In the technological innovation of realizing Prepress digital networking and printing multi-color and high efficiency, the overall revolution of printing technology can be completed only by using high-tech to achieve tensile strength and exquisite automation. At present, due to the unique advantages of UV glazing technology itself, it has obvious advantages in the development of post press processing, and is widely used in the surface finishing and processing of printed materials such as packaging and decoration, book covers, picture books, trademarks, advertisements, calendars, large decorations, posters and so on

glazing process can be divided into solvent volatile glazing, UV glazing (UV glazing) and heat curing glazing according to the drying method of glazing oil

advantages of UV glazing

uv glazing is UV curing glazing. It uses UV glazing oil, which can be cured in a very short time after being coated on the surface of printed matter and irradiated by UV light. Its basic principle is: under the irradiation of ultraviolet light, the photoinitiator in UV varnish absorbs radiant energy and forms free radicals or cations, which triggers the polymerization and cross-linking reaction between monomer and prepolymer, and solidifies into a three-dimensional polymer in a very short time

now, as people gradually understand and master UV glazing technology, and the price of UV coating is greatly reduced, UV glazing technology has been rapidly promoted and applied in the field of packaging and printing with its unique advantages. Data shows that the application of UV glazing technology is growing at a rate of% every 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 with other glazing methods, UV glazing has the following advantages:

1, safety and environmental protection

UV coating is used in UV glazing process. UV coating is composed of oligomers, active diluents, photoinitiators, photosensitizers and additives, with a solid content of 100%. There is no solvent volatilization factor, and it is a green product that is safe and does not pollute the environment. Especially in the current era of advocating "green packaging", the environmental protection advantages of UV glazing process in post press processing have been better recognized

2. Not limited by the type of substrate

3. Working at low temperature, it can be used for the printing of thermal substrate (such as plastic)

4. High product quality

uv coating has fast light curing speed, high hardness, good wettability, strong adhesion, and high interruptibility, wear resistance and gloss value. UV polished prints have smooth and bright surface, high hardness, friction resistance, not easy to scratch, and have the advantages of waterproof, no odor and so on

5. The substrate after glazing can be processed immediately and has high adaptability in cutting, forming, folding, etc

6. High efficiency and low cost

UV wavelength is nm, which is invisible light. UV curing adopts long wavelength ultraviolet (UVA) with a wavelength of 316nm. UVA curing speed is fast, and UV oil can be cured into a uniform coating within seconds. The production efficiency is high, and the general drying speed can reach meters/minute; Compared with the glazing and calendering process, the equipment covers a small area, and the comprehensive costs such as material consumption and energy consumption are reduced

uv glazing methods

uv glazing methods have many kinds, and there are also many classification methods, mainly including the following classification methods:

a. according to the relationship between glazing machine and printing machine

according to the relationship between glazing machine and printing machine, glazing can be divided into offline glazing and online glazing. Offline glazing uses a special glazing machine to polish the printed matter, that is, printing and glazing are carried out on their own special equipment. This glazing method is relatively flexible and convenient, with small equipment investment, and is more suitable for professional post press processing manufacturers. However, this glazing method increases the transportation and transfer between printing and glazing processes, resulting in low production efficiency; Online glazing directly connects the glazing unit to the printing machine, that is, printing and glazing are carried out on the same machine, with high speed, high production efficiency and low processing cost, which reduces the handling of prints and overcomes various quality faults caused by powder spraying. However, online glazing has high requirements for glazing technology, glazing oil, drying device and glazing equipment

b. according to the glazing method

according to the glazing method, glazing can be divided into roller coating glazing and printing glazing. Roller glazing is the most common way of glazing. The glazing oil is evenly coated on the surface of the print by the coating roller; Printing glazing: the glazing oil is coated on the print through the glazing plate, so local glazing can be carried out. At present, gravure glazing, flexo glazing, offset printing and silk glazing are often used

c. according to the type of glazing products

according to the type of glazing products, glazing can be divided into full width glazing, local glazing, extinction glazing and artistic glazing. The main function of full width glazing is to protect the printed matter and improve the surface gloss of the printed matter. Full width glazing is generally carried out by roller coating; Local glazing is generally to polish the graphic parts that need to be emphasized on the printed matter. The high gloss picture of the polished part is compared with the low gloss picture of the non polished part to produce a wonderful artistic effect. Local glazing is carried out by printing and glazing; UV matte oil is used for matting and glazing, which is opposite to the effect of heat shrinkable film and stretching film, which usually have high requirements on the tensile properties of materials. It reduces the gloss of the surface of printed matter, thus producing a special effect. Due to the stimulation of human eyes to a certain extent due to high gloss, matting and glazing is a popular glazing method at present; The function of art glazing is to make the surface of glazing products obtain special artistic effects. For example, using UV pearlescent glazing oil on the surface of printing products. 2. The basic properties of fillers will produce pearlescent effects on the surface of printing products, making printing products appear noble and elegant

film coated UV glazing pioneer and beech Xintiandi

UV glazing of film coated products is the method of coating the surface of printed matter and then printing one or two times of varnish on the whole or part to make the surface of printed matter obtain a bright UV varnish film. UV varnish on the coated products can enhance the light resistance of the ink and improve the gloss and three-dimensional sense of the printed matter. Forming a strong contrast. Either full plate glazing or partial glazing can be used

however, the following problems often occur in UV glazing of film coated products: first, the brightness is poor, mainly because the varnish is coated unevenly or diluted excessively, and the viscosity is too low. At this time, it is necessary to adjust the glazing machine and improve the viscosity of the varnish; The second is the adhesion of products printed due to too thick UV varnish coating; Third, the viscosity of UV varnish is too small and the coating is too thin, which will cause the surface of UV gloss oil layer to be scratched. It is necessary to improve the viscosity of UV varnish and increase the coating thickness; Fourth, there are white spots and pinholes on the surface of UV light oil layer, which requires a variety of possible reasons, such as: whether the UV light oil coating is too thin, whether the amount of ethanol diluent is too high, whether there is more dust on the surface of the film, etc; The fifth problem is that the light oil layer and the picture and text are staggered, which is caused by inaccurate overprint

although the UV glazing technology of film covered products has not appeared in China for a long time, its development speed is very fast, and it has achieved good response and application in both the field of commercial printing and the field of packaging printing. It can be said that the application prospect of UV glazing technology for film coated products is very broad

source: International Printing