Effect of moisture change of plate paper after calendering on die cutting precision

Update:05 May 2019
Summary:

In order to increase the beauty of the product and incr […]

In order to increase the beauty of the product and increase the surface finish of the color box, 70%-80% of the carton packaging needs to be glazed and calendered. The glazing is that the printed matter is evenly coated with a layer of varnish on the surface of the printed matter by a glazing oil roller, and then heated to dry the solvent to form a bright layer. Calendering is the re-processing on the basis of printing. With a high temperature of 100-130 ° C and a pressure of about 138 kg / cm 2 , the bright layer formed on the surface of the printed matter is denser and the brightness is higher.
Due to this special process, the water content of the paper itself is severely dehumidified in a short period of time, and the paper inevitably shrinks, and the amount of shrinkage is related to the paper structure and the initial humidity. Although its shrinkage has nothing to do with printing overprinting, it directly affects the precision of die cutting. For example, if a product has a long input size of X and a width of Y, if it is 5 on a pair of K paper and 3 vertical, after printing, a product with a pattern size of 3Y×5X will be obtained. The size of the back paper pattern shrinks, shrinking △X in the lateral direction, and shrinking △Y in the longitudinal direction. The product after die-cutting with the die of the original size is surely inaccurate in die-cutting precision, and even presses, Bleeding, the pattern is not centered. If the customer is not satisfied, the product will be partially or completely scrapped, causing undue losses to the company.
So how to avoid or reduce such errors in specific production? The simpler method is to make molds (die-cutting boards) according to different papers and different shrinkage after calendering, but this often seriously delays the production cycle, and die-cutting The size of the molding will be smaller than the original size. To this end, we should gradually explore the humidity characteristics of various papers commonly used in this unit and the horizontal and vertical shrinkage after calendering. Add this shrinkage amount evenly to the input size of the original when printing, so that the distance after final shrinkage, The entire graphic size meets the standard requirements, which also allows the die-cut version to be produced in advance to ensure the quality and cycle of the product.