There are many reasons for poor hot stamping, and the treatment methods are also different.
To sum up, it is mainly related to factors such as hot stamping temperature and pressure, ink formula, surface characteristics of printed parts, and the properties of anodized aluminum.
① Adding an appropriate amount of waxy detackifier, anti-sticking agent or non-drying oily substance to the ink will also cause the hot stamping to be weak. The solution is to first stick a layer of absorbent paper on the printing plate and press it again to absorb the wax and non-drying oil on the background ink layer, and then perform the hot stamping operation.
②Improper selection of anodized aluminum directly affects the fastness of bronzing. What type of anodized aluminum should be selected according to the size of the hot stamping area and the characteristics of the material to be hot stamped. According to the practical experience of some manufacturers, when choosing anodized aluminum, the hot stamping (general ink color) of ordinary products can be 88-1 type and KURZ PM type; the hot stamping of heavy ink printing materials such as cigarette packs and cosmetics (including printing gold and silver printing) Choose type 88-2; fine handwriting hot-stamping of anodized aluminum such as cigarette labels, cosmetic packaging, etc. has 88-3, 88-4, PM288, etc.; suitable for OPP or PET laminated paper and cardboard with UV ink, glazing There are 88-4 type, K series, LK series, and SP series for hot stamping anodized aluminum for paper and other products.
③When the hot stamping is not firm due to low hot stamping temperature or light pressure, the hot stamping temperature and pressure can be readjusted. Due to the difference of equipment and material to be stamped, stamping time and stamping temperature are different. For example, the high-speed circular press is fast, and the embossing line is in contact, and the hot stamping temperature will be higher than the circular or flat press. Generally, the hot stamping temperature for round pressing is about 190℃～220℃, round pressing is about 130℃～150℃, and flat pressing is about 100℃～120℃. In addition, the hot stamping time, hot stamping temperature and production efficiency are largely restricted by the transfer performance of anodized aluminum.
④ Too much powder on the surface of the printed parts or the surface contains additives such as debonding agent and bright paste, which hinders the adsorption of anodized aluminum and paper. The solution is to remove powder on the surface or solve it in the printing process.
⑤During the printing process, due to the excessive amount of dry oil added in the ink, the surface of the ink layer dries too fast and crystallizes, so that the hot stamping foil cannot be hot stamped. The solution is to prevent crystallization as much as possible during printing. Secondly, after crystallization occurs, the hot stamping foil can be removed, and the printed product can be air-pressed under heating to destroy the crystallization layer before hot stamping. Printed.