Printing and printing Gravure printing is divided into two processes: printing (original printing) and printing (reverse printing). It is more common to print in ore bags. Printing inks on printed materials (such as OPP), and then sandwiching them in the middle, there are other materials inside and outside, that is, three-layer composite bags. Such a bag is firm and clean, and it can prevent the leakage of the package, the contamination of the package with the ink, and the packaging of the liquid, food, and the like. As the name suggests, the ink is printed on the surface of the package and generally has no other compound. Common materials are basically tubular film, opaque film, single-layer film, etc., such as milk bags, bread bags, grocery bags and some food bags. The milk bag is special, because the printing material of the milk bag is black and white film or white film. The material itself is opaque, so it can only be printed on the surface, while other varieties are not required for the firmness and leakproofness of the package. Making a single-layer bag is inexpensive. Single-layer bags can only print ink on their surface because they prevent chemical ink from contaminating the package. The difference between printed and printed finished packaging is relatively simple. Because the printed packaging has a composite film on the printing surface, the printing ink on the bag will not be easily scraped off, and the color is brighter and smoother from the outside. The print is printed on the surface of the print, so the printed ink on the bag can be easily scraped off, and the appearance is darker and the hand feels rougher. The printing and printing are reversed in the order of color printing. The printing principle of printing is from deep to light (such as BK-C-M-Y-W), and the printing is from shallow to deep (such as W-Y-M-C-BK). Before designing the packaging, we must master whether the future printing of the packaging is printed or printed. If it is printed, the design restrictions are not very large, and can be routinely produced, but if it is printed, Consider the following:

1. The light mesh color should not be too shallow. Due to the ink and the process, the color on the shallow network is congenitally bad, and the level of the pattern is poor. Therefore, the gradient from deep to zero is used with caution. The most, no gradient, if you must add a gradient, etc. For the pattern of the shallow net, the color of the shallowest part should not be less than 25% of the color, and the 25% of the color amount will become blurred after the final printing, but it is visible, so the phenomenon that the gradient suddenly breaks can be avoided.

2. Try to avoid placing color photos. Complex color photographs will obviously lose texture due to insufficient coloring of shallow nets. For example, an orange will show a highlight in the surface of the cortex, so the printed result will have a large bump in the highlight. The anti-white, no excess. If you have to place a color photo, it is the most helpless solution to increase the amount of light in the high light or shallow network.

3. The pattern cannot be filled to the edge of the finished product. In two cases, if it is a cylinder film (the film blown from the raw material itself is cylindrical), it can only be flattened and printed, because its finished product is the most printed, large width, no surplus, so the pattern width Filling the film width will not leave room for the error of the film, and the deviation caused by filming during printing is unavoidable. At this time, if a deviation occurs, the ink is printed outside the finished product, which not only causes the finished product to lack a pattern but also misprints the ink onto the expensive rubber roller of the printing press to cause corrosion. The solution is to subtract 25 mm from the sides of the width of the film when designing the pattern. If the film is 500 mm wide, the design pattern width is 450 mm centered. In another case, such as a bread bag, the bagging method of the bread bag is eager, that is, the joint of the bag is bonded at a high temperature of the cutter. If there is ink at the joint at this time, the adhesion will be affected, and the finished bag will be opened and touched without any firmness. The solution is to leave a 5mm blank at each joint.

Third, the way to form a bag Before designing a package, we should also know its way of bagging, in order to design its pattern before the template. Generally, there are the following types of bag forming methods: three-side sealing bag, middle sealing bag, side sealing bag, tube bag, three-dimensional bag, side sealing punching bag, three-dimensional bag, sheet. Three-side sealing bag: that is, only one side of the opening is packed into the package before packaging, and the other three sides are heat sealed. Middle sealing bag: also called back sealing bag, the opening is sealed with three sides, but its sealing is on the back, and there is no heat sealing on both sides of the bag. Side sealing bag: Some milk bags and soy sauce bags are bagged in this way, and an obvious heat sealing is on the side. Cartridge: only the upper and lower seals are in the shape of a cylinder. Generally, there is no back pattern. If there is a back pattern, it needs to be made separately by two files. Punch bag: similar to the middle bag, but the bag has M-shaped concave on both sides, generally there is a lined box inside the bag. Side seal clip pocket: similar to the clip pocket, but the seal is not on the back, but on one of the sides of the M clip. Three-dimensional bag: It is tapered, with a bottom seat, the bag can stand upright, and some tea bags are three-dimensional bags. Sheet: No bag, such as the packaging of a beverage bottle, just a plastic film.