Author: Guangdong ink factory Tanhong Min
With the improvement of people's brand awareness, various beer manufacturers pay more and more attention to the image of beer packaging, not only make a fuss on the body label, but also seal the beer bottle with a cap label. The material of the beer cap and body logo is different. The body logo is usually printed on synthetic paper, and the cap logo is printed on pure aluminum foil. Therefore, the cap label has much higher requirements on the printing process and post-press processing than the body logo. In addition, for beer manufacturers, in addition to the requirement for a beautiful cap label, it is also required to be easy to operate when labeling, and meet the requirements of water resistance and frost resistance. In order to meet the requirements of both beer manufacturers and printing manufacturers, the gravure printing ink used for the beer cap label is very important. Here is a simple analysis of how to choose beer cap gravure printing ink.
Ink basic performance requirements and test methods
1. Printing ink adhesion fastness requirements
If the ink adhesion fastness is not enough, the printing factory may appear faded after printing, embossing, slitting and labeling in the brewery. Therefore, the adhesion fastness is the index that should be considered first when selecting ink. The method of detecting the adhesion fastness is usually to print the ink on the aluminum foil substrate and stick it with tape, if it does not fade, it is qualified, otherwise it is unqualified.
2. Printing ink gloss and vividness requirements
Although aluminum foil itself has a metallic mirror effect, if inks with good gloss and vividness can be used, the printed patterns will be more vivid and beautiful. As beer manufacturers, they certainly hope that their packaging will give people a high-end feel, so it is important that the ink has sufficient gloss and vividness.
3. Printing ink smoothness requirements
If the slip of the label is not enough, the label will stick together to reduce the work efficiency, but it should not be too slippery, otherwise the knife edge will slip during the post-printing, and even the production date and batch number may not be printed The phenomenon. Therefore, the smoothness of the printing ink should be appropriate.
The usual method of detecting slippage is to align two 20? × 20? Unembossed prints printed with the full version of the ink, face to face, and fix one of them to 30 ° and 45 ° respectively. Test: At an angle of 30 °, if the printing slips down, it means that the ink's smoothness is too high; at an angle of 45 °, if the printing does not slip down, it means the ink's smoothness is not enough. That is to say, the printed piece cannot slide down at an angle of 30 °, and can slide down at an angle of 45 °.
4. Requirements for water resistance and frost resistance of printing inks
In the summer, people usually drink beer after chilling it, and it feels refreshing, so it is required that the printing ink can resist water and not fade at low temperatures. The usual test method is to place the printed piece in the refrigerator for 8 hours or soak in ice water for 8 hours, wipe it by hand, and it will be qualified if it does not fade.
Selection and use of ink
1. Selection of gravure printing ink for beer cap label
Beer cap gravure printing ink can be divided into varnish, transparent ink and translucent ink according to the characteristics. It depends on the packaging requirements.
(1) If the printed part is required to have the light reflection effect on the metal surface, transparent ink should be used, but this type of ink is more expensive.
(2) If the printing color is bright, semi-transparent ink is generally selected; if you want to get a more vivid color, you can print a layer of varnish or white ink on the aluminum foil substrate, and then print the translucent ink. A method of applying a layer of varnish after printing translucent ink. In contrast, the former will get more vivid colors.
(3) Some labels have only a small part of the pattern, most of which are bare aluminum foil. At this time, a layer of varnish must be printed, otherwise the label is fragile and not easy to cut.
2. Use of beer cap gravure printing ink
After selecting the required ink type, the following methods are usually used during printing.
(1) Control of ink printing viscosity
The control of ink printing viscosity is usually adjusted according to the printing speed of the printing machine. If the machine speed is fast, the viscosity is lowered; when the machine speed is slow, the viscosity is adjusted higher. Usually follow the following principles (viscosity test conditions: use the 3 # Zahn cup test at room temperature 25 ℃).
â‘ When the speed of the printing press is 30 ~ 80m / min, the viscosity of the ink is controlled at 16 ~ 22s.
â‘¡When the speed of the printing press is 80 ~ 120m / min, the viscosity of the ink is controlled at 12 ~ 16s.
â‘¢When the speed of the printing press is 120 ~ 150m / min, the viscosity of the ink is controlled within 9 ~ 12s.
It is worth noting that in the printing process, to control the printing viscosity range of the ink, it is necessary to add solvent to the ink from time to time.
(2) Preparation of dilution solvent
Dilution solvents can be divided into three types: quick-drying, medium-drying and slow-drying according to the speed of volatilization.
â‘ For benzene-soluble inks, the usual dilution solvents are as follows.
Quick-drying type: toluene? Isopropyl alcohol? Ethyl acetate = 5? 3? 2.
Medium dry type: Toluene? Isopropanol? Butyl acetate = 6? 3? 1.
Slow drying type: xylene? N-butanol? Butyl acetate = 5? 3? 2.
â‘¡For alcohol-soluble inks, the usual dilution solvents are as follows.
Quick-drying type: ethanol? Ethyl acetate = 5? 5.
Medium dry type: Isopropyl alcohol? Butyl acetate = 6? 4.
Slow drying type: n-butanol? Butyl acetate = 5 ~ 5.
Generally, the dilution solvent is selected according to the printing speed. A fast-drying thinner should be used for a fast printing speed, and a slow-drying thinner should be used for a slow printing speed. According to the requirements of the dilution and resin precipitation, which destroys the ink, which is also the basis for ensuring the printing effect.
(3) Control of ink color
The aluminum foil substrate is different from other materials, as long as the color of the ink is slightly different, the color difference printed on the aluminum foil substrate will be very obvious, so the control of color density is very critical. In addition, when reducing the color density in the printing process, you cannot use dilution solvents blindly, but should be used with a diluent, because the dilution solvent will significantly reduce the viscosity of the ink, but the diluent only dilutes the ink, and does not reduce the ink Viscosity. Therefore, when adjusting the color density, the diluent and diluent are usually used together. For spot color inks, it is best to be able to use the spot colors prepared by the ink manufacturer, which can reduce the ink color difference.
In addition, printing manufacturers should accumulate their own printing experience data and adjust their printing technical parameters according to different printing conditions to ensure that they can achieve the best printing results.
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