The specific requirement is that the fiber direction of the paper is perpendicular to the axial direction of the bottle body; The water content is about 5% ~ 7%; When the humidity is 40% ~ 80%, a single label remains flat; The curl height of the front and back is not more than 3 mm; It should take more than 8 seconds for the back to curl into a tube when it meets water. In addition to the above elements, the printing quality should meet the requirements of wine labels, otherwise it will bring difficulties to labeling.
Quality problems in beer labels and their causes
1. uneven glue brushing (glue on the top and bottom, no glue in the middle or glue on the left and right). The main reason is that the beer label paper is uneven, and the positive and negative curl height exceeds 3 mm
The bid was abandoned. The main reason is that the curl height of the front of the beer label paper is more than 3mm, and the air between the labels cannot enter during the labeling process, and there are two or more labels when taking labels.
3. The label is pleated or warped (it's ok when the bottle is attached, but the four corners of the label are warped during transmission). The main reason is that the moisture content of label paper is low and it stretches quickly when it meets water.
At present, the technical level of most printing plants can meet the appearance requirements of beer labels. How to control the internal quality of beer labels and meet the labeling requirements is the key point of the process. From the above analysis, it can be seen that the main reason for the curling and warping of beer labels is the low moisture content of beer label paper. If the printing method is different from the post-press processing method, it is necessary to control the printing quality by controlling the moisture change of beer label paper.
Changes of water content in beer label paper under different printing methods
1. Offset labels are printed by single sheet, single color or multiple overprinting, and ink drying is mostly natural conjunctival curing. Because offset printing has ink balance, the water content of label paper is basically the same as that of printed matter.
2. Gravure labels are made by pre-drying, continuous multi-color overprint and winding. After each color printing, the ink is dried by drying and solvent evaporation, and the label will lose water after repeated drying.
According to the law of "paper is wet, it will stretch, while paper is dry, it will shrink". When paper is stretched, it will print offset labels, while when paper is shrunk, it will print gravure labels. Therefore, if the process of gravure printing beer label is not well mastered, the finished product will curl when wet, which will lead to the failure of labeling. How to solve the problem of water content change of gravure beer label to meet the requirements of wine bottle labeling? Might as well pay attention
The following points.
Matters needing attention in gravure printing beer labels
1. Moisture regain: the moisture content of the label paper is restored after printing;
2. Setting: according to different paper properties, adjust the amount of water supplement in the moisture regain process;
3. Leveling: the single finished product after cutting should be leveled;
4. Keep the air humidity in the production workshop.