With packaging The rapid development of the printing industry, the application of hot stamping technology is more and more extensive, especially in the packaging boxes of commodities such as tobacco, wine, food, cosmetics, etc., its application can often play a finishing touch and highlight the design theme. However, the following three types of hot stamping processes are difficult to control and require special attention.
01 hot stamping on UV varnish
UV glazing can improve the gloss of printed products. Its unique high-gloss effect is recognized by customers. It is hot stamping on UV varnish. Although it can get very good visual effect, its process is difficult to control. Since the current hot stamping properties of UV varnish are not mature enough, the resin components and additives of UV varnish are not conducive to hot stamping.
However, the process of hot stamping on UV varnish is unavoidable when processing certain products. For example, the printing of small boxes of "good quality good days" flip-top cigarettes requires three steps of offset printing , hot stamping and glazing in the original production process. After changing to new materials, it can be done after offset printing and glazing. Printing, this can reduce one process, reduce the impact of 1 UV curing, thus avoiding the phenomenon of paper die-cutting, greatly improving production efficiency and reducing scrap rate.
However, at this time, it is necessary to stamp on UV varnish, which puts a high demand on UV varnish and hot stamping aluminum. The author believes that we should pay attention to the following aspects.
(1) Pay attention to controlling the amount of varnish when glazing. UV varnish must have a certain thickness to achieve high brightness, but too thick varnish layer is not good for hot stamping. Generally, when the UV varnish layer is applied by offset printing, the amount of glazing is about 9g/m2. After reaching this value, if it is necessary to increase the brightness of the UV varnish, the coating process parameters (coating roll wire angle and network cable) can be adjusted. A number of) and printing equipment performance (printing pressure and printing speed, etc.) to improve the smoothness and brightness of the varnish layer.
(2) Try to ensure that the varnish coating of the whole batch is relatively stable, and the varnish layer should be thin and flat.
(3) Reasonable selection of hot stamping materials. The hot stamping material is required to have high temperature resistance and good adhesion, and the adhesive layer has good affinity with the resin of the UV varnish.
(4) Accurately adjust the temperature and pressure of the hot stamping plate, because excessive pressure and temperature will destroy the ink performance and make hot stamping more difficult.
(5) The hot stamping speed should not be too fast.
02 first hot stamping
The first hot stamping is a new idea in the design of cigarette packages and the printing industry . The cigarette packs produced by our company mainly include “Golden Famous World Show†(small box) and “Green Jiaoziâ€. The process needs to pay attention to the following matters in actual operation:
(1) The requirements for hot stamping aluminum are very high, and the hot stamping position is required to be very accurate. The surface of the hot stamping pattern is smooth and bright, non-foaming, non-paste, no obvious wiping and scratching, and the edge of the hot stamping pattern. Can not have obvious indentations;
(2) For white cards and glass cards, special attention should be paid to the protection of semi-finished products. In the production process, the influence of various unfavorable factors such as paper deformation should be minimized. This is a smooth process after the hot stamping process and the product qualification rate. Improvement is very helpful;
(3) The adhesive layer of the electrochemical aluminum should have a very high adhesion (special adhesive layer should be developed for the cigarette product if necessary), and the surface tension of the electrochemical aluminum should not be less than 38mN/m;
(4) Before hot stamping, the positioning film must be output first, and the accurate position of the hot stamping plate can be adjusted to ensure the accuracy of hot stamping and printing overprinting;
(5) Before mass production, it is necessary to test the product after hot stamping. The method is to directly reverse the hot stamped aluminum with 1 inch transparent tape to observe whether there is gold powder, defective or hot stamping. Phenomenon, which prevents a large amount of waste during the printing process;
(6) When making film, pay attention to the range of unilateral shrinkage and expansion, usually within 0.5mm.
03 holographic positioning hot stamping
Holographic positioning hot stamping can be applied to printed products with anti-counterfeiting patterns, which greatly improves the anti-counterfeiting ability of the products, and at the same time improves the grade of the products. Holographic positioning hot stamping has very high control requirements for temperature, pressure and speed, and the hot stamping model also has a great influence on its effect. The "Taishan Wangyue" and "Red Jiaozi" used in the cigarette packs produced by our company.
In holographic positioning hot stamping, the accuracy of overprinting is directly related to the quality of the product. The hot stamping film should be expanded by 0.5mm on one side. Usually holographic positioning hot stamping uses hollow stamping. In addition, the cursor of the holographic positioning hot stamping material should be uniform, and the patterns should be evenly arranged to make the machine track the hot stamping cursor accurately.
04 Other notes
(1) The appropriate anodized aluminum must be selected according to the type of substrate. When hot stamping, you must master the temperature, pressure and speed of hot stamping, and treat it according to the different hot stamping materials and hot stamping area.
(2) Paper, ink (especially black ink), dry oil, composite adhesive, etc. with suitable properties should be selected. The hot stamping must be kept dry to avoid oxidation or damage of the hot stamping layer.
(3) The general anodized aluminum specification is 0.64m×120m, one roll for every 10 rolls; the large roll or other special specifications with a width of 0.64m and a length of 240m or 360m can be customized.
(4) When storing aluminum, it should be protected from pressure, moisture, heat and sun, and placed in a cool and ventilated place.
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