Detailed explanation of glazing materials and equi

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Post press glazing technology: a detailed explanation of glazing materials and equipment

in the printing industry, the continuous upgrading of equipment accessories has brought continuous technological innovation. Today, the Chinese paper industry will introduce the glazing process from the printing process

glazing process has a long history. With the development and progress of continuous application, the content of science and technology is also higher and higher, and the scope of application is wider and wider. In particular, the rapid development of water-based coating glazing and UV coating glazing that meet the requirements of safety and environmental protection, as well as the wide application of various online glazing methods, have greatly promoted the popularization, application and technological progress of glazing technology

printing glazing vs traditional lamination

the traditional lamination process has gone through many years, and we are no longer unfamiliar with its process. Compared with the glazing process, they have similarities and differences. The so-called printing polish is to reprint one or two times of polish with a field plate or a graphic plate on the surface of the copy that has completed the graphic printing, so as to obtain a bright and transparent film on the surface of the print. Common glazing methods include oily glazing, aqueous glazing and UV glazing

printing glazing can enhance the light resistance of the ink, increase the heat and moisture resistance of the ink layer, and play a role in protecting the imprint, beautifying the product, and replacing the film covering. Compared with film coating, printing and glazing are cheap and simple. They can be used for full plate glazing or local glazing

1 environmental protection

first of all, from the perspective of simple environmental protection, water-based and UV are in line with the trend. Because there are two layers of pollution, white pollution and plastic film pollution. The cover after water-based glazing and UV glazing can be directly recycled without any further treatment

in addition, from the perspective of the general environment of market application, in addition to the packaging of food, drugs and cosmetics, even those electronic products that do not come into direct contact with the human body, because the corporate culture advocates environmental protection and is proud of its original ingredients, it is gradually required to adopt the pollution-free printing method of glazing

with the economic exchanges and cooperation of various countries, a considerable number of printing and packaging enterprises in the coast and the mainland have outsourcing businesses, while western countries have high requirements for environmental protection, and pollution-free water-based glazing and UV glazing have developed quite mature. Especially in food packaging, pharmaceutical packaging and other fields, Europe has set strict standards, and the survival space of film covering and oily glazing that do not meet the standards has been very small

the traditional film covering process will not fade out of the market completely because it can increase the thickness and toughness of the paper and its good water resistance. However, in the face of the improvement of global environmental awareness, products are required to be recycled or biodegraded. The film covering process must strive to improve the pollution of products, working environment and external environment in order to have greater living space

2 cost and efficiency

according to the actual application, the cost of film coating is higher than that of glazing. In the industry, the quotation of glazing is generally no more than half of the film covering, so the traditional film covering has no advantage in cost

the film covering speed of the traditional film covering machine is 30m/min~75m/min, while the current online glazing equipment can fully match the speed of the printing machine, and the stability of the glazing quality has been greatly improved. Without considering the specific requirements of customers, the glazing process is more economical in terms of efficiency

it is worth noting that the transfer film process, which has been used for many times in the past two years, has broken through the boundaries of traditional film covering, and has initially shown its advantages in the application of related color boxes and cigarette packs

second, the characteristics of Polish

there are many kinds of polish, but the commonly used polish can be roughly divided into three categories: Oil-based polish, water-based polish and UV polish. According to the practical application trend of varnishes and the improvement of environmental protection requirements, the use of oily varnishes will be increasingly reduced, while the application space of waterborne varnishes and UV varnishes is very broad. This section mainly introduces waterborne varnishes and UV varnishes

1 water based varnish

water based varnish (called water based varnish in English, also known as dispersed varnish) has a great impact on the cost of all cells. It is mainly composed of water-soluble resin and water-dispersive resin. The water-based varnish is non-toxic and tasteless, eliminates the harm to human body and environmental pollution, and has the advantages of fast drying speed, good film transparency, stable performance, wide equipment adaptability The polish surface has the characteristics of good wear resistance and flatness, wide post press processing adaptability, good heat sealing performance, safe and reliable use, convenient storage and transportation, etc., which have attracted more and more attention from food, medicine, tobacco carton packaging and printing enterprises

the following typical problems should be paid attention to when using UV water-based glazing oil:

① how to ensure that the underlying ink can be fully dried after coating water-based glazing oil, first of all, to ensure the air permeability of the water-based glazing oil, so that the wet ink layer can be exposed to air by the Plexiglas project manager to dry the oxidized conjunctiva; In addition, this problem can also be solved by moderately increasing the hot air temperature

② the gloss of water-based varnish coating is lower than that of UV varnish. In practice, a small amount of high boiling point solvent can be added to water-based varnish to moisten lotion particles and promote them to form a film with good flatness, so as to improve the surface flatness of the film, and finally achieve the purpose of improving the gloss of water-based varnish coating

2uv glazing oil

uv glazing is a method of curing glazing paint by UV (the abbreviation of ultra violet). It has the characteristics of rapid curing of paint and low temperature curing, and the ink is not easy to fade, which is helpful to solve many problems in the gloss processing of paper printed matter. Therefore, it has been widely used in the gloss processing of paper containers, trademarks, book covers, packaging boxes and other printed matter

uv varnish contains almost no solvent, and the emission of organic volatile matter is very small, so air pollution is reduced; UV varnish does not contain solvents, so it does not need heat energy during curing, and its curing energy consumption is relatively small. In addition, UV varnish has strong affinity for ink and firm adhesion; UV glazing is polyamide (nylon oil has high effective components, less volatilization, and relatively low consumption; the printed surface after UV curing is more wear-resistant, drug-resistant and chemical resistant, and has good stability, and can be scrubbed with water and ethanol; UV glazing products are not easy to adhere, and can be stacked up after curing, which is conducive to the processing of subsequent processes.

uv glazing oil should pay attention to the following typical problems when using:

① UV glazing oil is not suitable for operation on permeable paper 。 Because the low molecular materials in UV paint are easy to penetrate into the paper, causing the paper to darken or even soak. At present, most UV varnishes are used on printing paper with aluminum coating

② the main reasons for the poor adhesion of UV varnish are: the crystallization of printing ink layer or the improper use of ink additives and antiskid agents. The printing process should be improved, and ink additives should not be used or used less

③ the main reasons for the poor brightness of UV varnish are: poor paper quality, different surface roughness, uneven coating or too thin varnish, low viscosity and other reasons

three glazing equipment

printing glazing equipment is divided into glazing machine (including calender) and printing glazing linkage machine. The polishing machine is generally operated by a single machine, with slow processing speed and slightly poor quality stability, and often needs to be calendered again. At present, large offset printing manufacturers at home and abroad mostly use printing online glazing to improve the glazing speed and quality. It can be said that printing online glazing is the development trend of glazing machinery

printing online glazing can be roughly divided into two categories:

1 printing and glazing linkage machine

printing and glazing linkage machine is used for glazing and coating by printing unit. Its basic form is to use the last printing sheet of sheet fed offset press for glazing and coating. There are generally two forms of glazing and coating by using the printing unit: one is to use the wetting device for glazing and coating, and the other is to use the inking device for glazing and coating

using the existing printing unit on the sheet fed lithographic press for glazing and coating, the production covers a small area, while saving additional equipment investment. It is the simplest and most economical option at present. However, its glazing and coating effect is not very good, and it is only suitable for products with simple coating and low requirements

2 printing machine online glazing device

online glazing is carried out by an independent glazing unit on the printing machine, which has high production efficiency and stable glazing quality. It can use resin plate or traditional rubber cloth for glazing. Like the printing device, it is all monitored and controlled by the printing machine control center, such as horizontal and circumferential registration adjustment, diagonal registration adjustment of photosensitive resin plate, etc

the online glazing device can perform thick and uniform glazing coating for the whole surface of the substrate or local graphics and texts. The glazing can be done with blanket or flexo for fine local glazing; It can be engaged in both water-based glazing and UV glazing

when online glazing system is selected, the advantages of roller glazing are obvious, but the investment is relatively large. Roller glazing can accurately control the thickness of the glazing coating, does not depend on the printing speed, and is rarely affected by the viscosity fluctuation of the glazing oil. A typical glazing device is the closed doctor blade system, which is composed of ceramic grain roller, closed doctor blade and flexible resin coated plate roller. This online polishing is fast and efficient, and the corrugated roller can be replaced quickly. Selecting different corrugated rollers can accurately complete the coating as required, which can not only obtain a full glazing coating, but also carry out accurate local glazing

glazing has become an important means of post press processing. With the continuous maturity of glazing technology and the increasingly clear development direction of non pollution, consistent operation and diversification of glazing products, it will also achieve great results in the processing of foreign trade export product packaging. Glazing technology will be the most promising surface processing technology of packaging and printing

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