Commodity packaging uses a variety of processes to make new decorative solutions. Good solutions are those that use a lot of plastics and films with variable surface characteristics, new effect colors, and glazing systems for finishing. However, not all of them can be processed as the designer wants, and they can be printed, finished and processed without problems into attractive prints. The more finishing methods used, the more specialized the entire process. Before making a decision to invest in equipment, it is important to carefully consider which process is best for which product and which new business area can be used to produce what product.
Flexible plate unit and sheet-fed offset printing for online finishing
In the packaging and printing industry, most sheet-fed offset presses are equipped with a flexographic coating unit, and this situation is also increasing in the field of parts printing. Offset printing companies began to use flexographic printing technology in this way. Equipped with a cavity scraper and anilox roller, it can be used for glazing, and it can also perform accurate local glazing. The flexographic printing unit is located behind the offset printing unit. It is usually used for online glazing or partial glazing of printed products. When the flexographic printing unit is located in front of the offset printing unit, the surface of the printing material can be pretreated, for example, white varnish is coated on metal paper or transparent plastic, and the flash effect is printed by the color offset printing method in the subsequent process.
The advantages of offset printing are high printing quality, low pre-press and plate costs. The characteristic of flexographic printing is that it can form a thicker coating with a simpler process and can adapt to the printing of larger pigment particles. Flexographic printing ink is similar to thin gravure ink in viscosity. Compared with offset printing, it can form a thicker and uniform ink ink layer, and use different anilox rollers to change the ink film thickness. The particle size of metal pigments for offset printing is 3.5 μm, and the particle size of metal pigments for gravure and flexographic printing is 8 to 9 μm. These flexographic printing units are commonly used to coat opaque white coatings, milky white coatings, metal coatings, foam printing and scattering applications, and UV glazing coatings.
Sheet-fed flexo printing machine for offline finishing
Sheet-fed flexographic printing machines are often used as coating machines in corrugated board printing. The new sheet-fed flexographic printing machine for packaging printing and finishing is equipped with a gripper conveying system to ensure accurate conveyance between the printing unit and the printing unit. The printed materials range from thin paper to cardboard with a thickness of 1.25mm.
The design of the sheet-fed flexographic printing machine is the same as that of the sheet-fed offset printing machine. There are two flexographic printing units in the offset printing unit, which can be used as a varnishing machine for coating UV coating or effect coating. Some special coating methods require thick coating, such as foam printing, fragrance printing, shielding coating, gum coating, iridescent printing and thick pigment coating for metal effect. This type of machine can precisely control the quantity of coating.
High-quality packaging requires advanced finishing and requires multiple coating units / flexographic printing units. If the five or six printing presses with the glazing unit are only used for glazing or multiple coating, it will soon become a "bottleneck" in production. Sheet-fed flexo printing machines used offline can also enter the field of high-quality packaging and finishing.
Sheet-fed offset press and UV technology with multiple finishing effects
The volume of printing business using UV technology has increased by nearly three times. UV technology represents the highest level of quality and has the characteristics of high efficiency and good consistency when glazing. Of particular interest is that the UV coating has a high gloss value and excellent scratch resistance. Under the UV lamp radiation of the printing machine, the UV ink and varnish film are cured within a fraction of a second, and the printed sheet can be directly post-processed. The problems of powder spraying and solvent evaporation naturally disappeared.
However, it is not simply to buy equipment to master the UV printing and finishing process. Printing plants that use UV technology need to accumulate various experiences and digest the increased investment costs, material and energy costs. In factories where traditional printing and UV technology are mixed, it is necessary to plan the conversion time and adjust the printing parameters. UV prints still smell, which needs to be further improved. However, the advantages of UV far outweigh the disadvantages. A wide variety of non-absorbent printed materials is a real challenge for parts printing, packaging and label printing.
Launch mixed operations
UV printers need to be adjusted according to the special requirements of printing plants and their products. Even for small format offset printing, the powerful UV technology is equivalent to the UV technology used in large and medium format offset printing in all aspects. Those who are new to UV, it is better to start from the mixed operation of UV and traditional printing, the original finishing and glazing will operate as a UV printer. In the future, the waterless UV sheetfed offset printing machine will also reveal the finishing advantages in non-absorbent printing materials. This printing method can image CTP anhydrous offset printing plates and CTP traditional offset printing plates on the same direct plate making machine. , Without chemical development.
The demand for plastic films is also increasing. In the past, silk screen printing monopolized this market share, and today's offset printing plants have also entered this high-selling market because of the use of UV technology. However, screen printing is now also using UV technology to compete fiercely with its strong competitors. Because the high temperature generated by the ultraviolet beam generator affects the dimensional stability, it threatens the printing and finishing processes that require precise overprinting. Therefore, the UV system needs to greatly reduce the amount of radiated light and cure in an inert gas chamber filled with nitrogen.
Online double coating
The double coater is a model that replaces the pure UV Machine. The double coater can use UV coating device to coat much cheaper traditional ink on the machine, and can also use some special color inks that have been tested. However, the prerequisite is that there are two coating units on the printing press, and the drying part is located between the two coating units.
Finishing process worthy of careful consideration of hybrid technology
The sheet-fed offset press used can use either traditional mineral oil-based inks or mixed inks, but the printing press must be modified accordingly. Since the surface chemical properties of the mixed ink are ultimately the same as those of the UV ink, it is necessary to avoid the disadvantages of poor coating adhesion and impurities in the bright layer.
High gloss and matt effect can be realized in one printing press. Use mixed colors to print on the first printing unit, then the ink is dried on the UV intermediate drying device. The individual elements are then coated with traditional inks and traditional printing varnishes, followed by the final UV coating and hardening. In all parts of the graphic elements printed with mixed inks / varnishes, the interaction of normal inks and UV varnishes A matte, shiny, structured surface is formed, similar to a plastic coating, which is both visible and touchable, showing an interesting design feature. From this point of view, there are still many options for different combinations of effects.
It can be said that hybrid technology is not only a way of UV technology, but also a system. Manufacturers who cannot fully use UV machines in parts printing will use hybrid technology.
Use of natural gas (natural gas or liquefied petroleum gas) and to help with the help of a certain shape of flame thrower mixed combustion of high temperature flame to PP PE surface oxidation treatment, can greatly improve the surface tension of the plastic material, improve the printing ink adhesion molecules, prevent ink from falling out, flame treatment is polar plastic containers for surface treatment technology of printing quality stability is the most effective. It can be made into a flame processor independently, and it can also install the Automatic Screen Printing Machine to form the production line.
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