[China Packaging Network News] Since the heat shrinkable film is a stretch oriented in the production process, and heat shrink during use of the thermoplastic film. Therefore, no matter which printing method is adopted for printing, the horizontal and vertical shrinkage of the material and the allowable deformation error in each direction of the decorative graphic after shrinking must be taken into account before the design of the surface pattern, so as to ensure the pattern shrinking onto the container, The exact reduction of text and barcode.
1. The direction of the pattern Whether the heat shrinkable film is gravure or flexographic printing, the printing is mainly printed in India, and the direction relative to the pattern on the printing plate should be positive. Nowadays, there is also a printed shrink film. In this case, the pattern on the plate should be reversed.
2, the level of the pattern is limited by the shortcomings of the flexographic printing, if the shrink film using flexo, the image level should not be too delicate, while the use of gravure can require more rich image layers.
3, the size of the design of the heat shrinkable film material used for printing lateral shrinkage rate of 50% to 52% and 60% to 62%, under special circumstances can reach 90%, longitudinal shrinkage requirements in 6% to 8%. However, when the film shrinks instantaneously, due to the limitation of the container, the horizontal and vertical directions cannot be completely contracted. In order to ensure accurate reduction of the printed pattern, text, and bar code, the shape of the container must be taken into consideration, and the correct size is calculated according to actual conditions. Deformation rate. For heat-shrinkable labels that need to convert the sheet-like film into a tube shape and use an adhesive to seal the overlapped parts together, care should be taken not to design graphics at the sealing area, so as not to affect the adhesion fastness.
4. Placement of bar code Usually, the bar code placement direction should be consistent with the printing direction, otherwise it will cause the bar code lines to be distorted, thus affecting the scan results and causing misreading. In addition, the color selection of label products should be based on spot colors as much as possible, and the production of the white version is a must, and it can be made full or hollowed out according to the actual situation. The color of the bar code should follow the general requirements, that is, the color of the bar and the empty should match the bar code color matching principle. Printing material selection. The printing of heat shrink labels has been briefly analyzed above, affecting their quality. In addition to controlling the printing process, materials play a decisive role. Therefore, choosing the right material is the key. The thickness of the film material is determined according to the application field and cost of the heat shrink label, the characteristics of the film, the shrinkage property, the printing process, and the labeling process requirements. Generally, the film thickness of the shrink film label should be 30 μm-70 μm, and 50 μm, 45 μm, and 40 μm are more commonly used, depending on the labeling performance of the labeling device. For the selected label material, the shrinkage of the film material is generally required to be within the application range, and the transverse (TD) shrinkage is higher than the longitudinal (MD) shrinkage. The transverse shrinkage of commonly used materials is 50% to 52% and 60% to 62%, and in special cases it can reach 90%. The longitudinal shrinkage requirement is 6% to 8%. In addition, because the shrink film is very sensitive to heat, high temperatures must be avoided during storage, printing, and shipping.