Glazing and calendering process solutions in the h

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Solutions to glazing and calendering in printing technology (I)

a. what is glazing

glazing is to apply (or spray, print) a layer of colorless and transparent paint (glazing oil) on the surface of the print. After leveling, drying and calendering, a thin and uniform transparent bright layer is formed on the surface of the print. Glazing includes overall glazing, local glazing, gloss glazing, matte (extinction) glazing and special paint glazing

b. why should printed matter be polished

glazing is to beautify printed matter, protect printed matter, strengthen the publicity effect of printed matter and improve the practical value of printed matter. After polishing, the surface of the printed matter appears smoother, making the incident light produce uniform reflection, and the ink layer is brighter. Glazing is the process of coating the surface of printed matter with glazing oil. Take appropriate measures to protect the surface of paper or paperboard prints after printing and before final processing. After the printing is polished, a bright film is covered on the surface. Its application scope includes:

① book binding, such as envelopes, covers, inserts, so we should try our best to avoid the occurrence of the above phenomena in our work, as well as calendars, calendars, advertisements, publicity samples, etc. after glazing, the printed matter can increase luster and bright colors

② packaging and decoration paper products, such as paper bags, envelopes, trademarks, etc., play a role in beautifying and protecting goods after polishing

③ cultural goods, such as playing cards, postcards and gold printed patterns, can resist mechanical friction and chemical corrosion after polishing

④ daily necessities, food, etc. Such as cigarette, food, detergent and other trademarks can play a moisture-proof and mold proof role after polishing

⑤ pressing copper foil on the hard cover can make the appearance beautiful. Its brightness is very high, much like gold. If the copper is less and the base is not firmly combined, good adhesion can be obtained after glazing

c. what are the technical requirements for polish

in addition to the characteristics of colorless, tasteless, strong gloss, rapid drying and chemical resistance, an ideal glazing oil must also have the following properties

① the film has high transparency, no discoloration and environmental protection. Efforts are made under the trend of lightweight, intensive and ecological in the automotive industry. In order to obtain excellent glazing effect for decoration printing, it depends on the formation of a colorless and transparent film on the surface of the printing sheet, and the graphics and texts do not change color after drying. And it should not change color or turn yellow due to the sun or long use time

② the film has certain wear resistance. Some polished prints require certain wear resistance and scratch resistance after polishing. Due to the adoption of assembly line production processes such as high-speed box making machine, cardboard box packaging machine device and book cover, the surface of printed matter is subject to friction, so it must have wear resistance

③ it has certain flexibility. The bright film formed by any kind of polish on the surface of printed matter must maintain good elasticity to adapt to the flexibility of paper or paperboard, and will not be damaged or cracked, or fall off

④ the film has good environmental resistance. Some of the printed matter after glazing is used to make all kinds of packaging cartons. In order to protect the packaged products, the environmental resistance of the glazing film must be good. For example, the packaging of food, cigarettes, cosmetics, clothing and other commodities must be moisture-proof and mildew proof. In addition, the chemical properties of the dried film should be stable. The performance cannot be changed due to contact with weak acids or bases and other chemicals in the environment

⑤ it has a certain adhesion to the surface of printed matter. Due to the influence of the integral density value of the graphic ink layer on the surface, the surface adhesion adaptability of the printed matter is greatly reduced. In order to prevent the film from cracking and falling off in use after drying, it is required that the film has strong adhesion, and has a certain adhesion to the ink and various auxiliary materials for ink mixing

⑥ good leveling and smooth film surface. There are many kinds of printing materials for printing. In addition to the influence of printing pictures and texts, there are great differences in surface absorption, smoothness, wettability and so on. In order to make the glazing paint form a smooth film on different product surfaces, it is required that the glazing oil has good smoothness and the film surface is smooth after film formation

⑦ wide adaptability for post press processing. After the printing is polished, it generally needs to go through post-processing, and the industry voice is weak, such as molding, hot stamping, anodized aluminum processing, etc. Therefore. It is required that the post press processing adaptability of the glazing film should be wide. For example, the heat resistance is good, and the bonding phenomenon cannot occur after hot stamping anodized aluminum; It has high solvent resistance, and the dried film can not bubble, wrinkle and stick due to the influence of adhesives in post-processing

(to be continued)

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