How to improve the hot stamping process of printed matter
From the basic process of hot stamping, it can be seen that the three basic elements of hot stamping are: temperature, pressure and hot stamping time. In order to obtain the ideal hot stamping effect, the process parameters such as hot stamping temperature, hot stamping pressure, and hot stamping speed must be reasonably mastered; In addition, the quality of raw materials related to hot stamping must also be guaranteed, such as: the hot stamping adaptability of the substrate, the performance of anodized aluminum materials, and the quality of hot stamping plates. If there is a problem in a certain link, it will definitely affect the final hot stamping effect.
Choose the right substrate. There are many substrates that can be broiled, usually paper, such as: coated paper, whiteboard paper, white cardboard, cloth paper, offset paper and so on. But not all paper hot stamping effect is ideal, if the surface is rough, the paper is loose, such as for book paper, poor offset paper, etc., because the anodized aluminum layer can not be well attached to its surface, the unique metallic luster can not be well reflected, and even hot stamping can not be printed, therefore, the hot stamping substrate should be selected with dense texture, high smoothness, large surface strength of the paper, so as to obtain a good hot stamping effect, the unique anodized aluminum luster is fully reflected.
Choose the appropriate anodized aluminum model according to the different substrates. The structure of anodized aluminum has 5 layers, namely: polyester film layer, shedding layer, color layer (protective layer), aluminum layer and adhesive layer. There are many models of anodized aluminum, such as No. 1, No. 2, No. 8, No. 12, No. 15, etc. In addition to gold, there are dozens of colors such as silver, blue, brown red, green, and red. The choice of anodized aluminum is not only to choose the right color, but also to choose the corresponding model according to the different substrates. Depending on the model, its properties and the range of materials suitable for ironing are also different. Under normal circumstances, the most used hot stamping of paper products is No. 8, because No. 8 anodized aluminum has moderate adhesion and good gloss, which is more suitable for general printing paper or varnished paper and lacquered cloth hot stamping. If hot stamping is done on hard plastic, you should choose another corresponding model, such as No. 15 anodized aluminum.
The quality of anodized aluminum is mainly checked by visual inspection and hand feeling, such as checking the color, brightness and trachoma of anodized aluminum. Good quality anodized aluminum requires uniform color, smooth and clean after hot stamping, and no trachoma. The fastness and tightness of anodized aluminum can generally be checked by rubbing it by hand or trying to stick its surface with scotch tape paper. If the anodized aluminum is not easy to fall off, it means that the fastness and tightness are better, and it is more suitable for hot stamping fine text patterns, and it is not easy to paste the plate when hot stamping; If the anodized aluminum falls off one after another when gently rubbed, it means that its tightness is poor and can only be used for hot stamping with sparse graphics and texts; In addition, pay attention to the broken ends of anodized aluminum, the fewer broken ends the better. It is worth noting that anodized aluminum must be properly kept, should be stored in a ventilated and dry place, can not be mixed with acid, alkali, alcohol and other substances, and there must be moisture-proof, high-temperature, sunscreen and other measures, otherwise anodized aluminum will shorten the service life.
Make a hot stamping plate. Hot stamping plates generally have copper plates, zinc plates and resin plates, relatively speaking, copper plates are the best, zinc plates are moderate, and resin plates are slightly worse. Therefore, for fine hot stamping, copperplate should be used as much as possible. For hot stamping plates, it is required to have a smooth surface, clear graphic lines, smooth edges, and no pitting and burrs. If the surface is slightly uneven or slightly bruised or fluffy, you can gently wipe it with fine charcoal to make it smooth and smooth. The depth of the hot stamping plate should be slightly deeper, at least 0.6mm or more, and the slope should be about 70 °, so as to ensure that the hot stamping graphics and texts are clear, reduce the occurrence of continuous sheets and paste, and improve the printing resistance. The design of the hot stamped text, lines and patterns is very particular. The picture and text should be as thick and thin as possible, sparse and reasonable, if it is too small and too fine, it is easy to lack strokes; If it is too thick and too dense, it will be easy to paste the plate. Control the hot stamping temperature. The hot stamping temperature has a great influence on the melting degree of the hot melt silicone resin shedding layer and the adhesive, and the hot stamping temperature must not be lower than the lower limit of the temperature resistance range of anodized aluminum, which is the lowest temperature to ensure the melting of the anodized aluminum adhesive layer.
If the temperature is too low and the melting is not sufficient, it will cause the hot stamping to be unsuccessful or the hot stamping is not firm, so that the imprint is not strong, incomplete, missing strokes or flowers; At the same time, the high temperature will also oxidize and polymerize the synthetic resin and dye in the color layer, blistering or fogging spots, and lead to oxidation of the surface of the aluminum layer and the protective layer, so that the hot stamping product will reduce its brightness or lose its metallic luster. Generally speaking, the electric heating temperature should be adjusted between 80~180 °C, and the electric heating temperature is relatively higher if the hot stamping area is larger; On the contrary, it is lower. The specific situation should be determined according to the actual temperature of the printing plate, the type of anodized aluminum, the condition of the picture and text, etc., usually to find out the most suitable temperature through the test ironing, and the lowest temperature and can be embossed out of the clear graphic lines as the standard.
It is necessary to reasonably grasp the hot stamping pressure. The hot stamping pressure has a great relationship with the adhesion fastness of anodized aluminum. Even if the temperature is suitable, if the pressure is insufficient, the anodized aluminum cannot be firmly adhered to the substrate, or the phenomenon of fading and blotting will occur; Conversely, if the pressure is too high, the compression distortion of the liner and substrate will be too large, resulting in pasting or coarse imprints. Therefore, the hot stamping pressure should be carefully adjusted.
When setting the hot stamping pressure, the main considerations should be: the properties of anodized aluminum, the hot stamping temperature, the hot stamping speed, the substrate, etc. Generally speaking, the hot stamping pressure should be less when the paper is strong, the smoothness is high, the printed ink layer is thick, and the hot stamping temperature is high and the speed is slow; Otherwise, it should be larger. In addition, similar to the hot stamping liner should also be noted, for smooth paper, such as: coated paper, glass cardboard, it is best to choose a rigid liner paper, so that the imprint obtained is clearer; On the contrary, for coarser paper with poor smoothness, it is better to have a softer liner, especially if the hot stamping area is large. In addition, the hot stamping pressure must be uniform, if the trial printing is found that the local hot stamping is not on or produces hemp, it may be that the pressure here is uneven, you can put thin paper on the flat plate at the place, and make appropriate adjustments.