Heat shrinkable film is a kind of film label printed on plastic film or plastic pipe with a special ink. In the labeling process, when heated (about 70℃), the shrink label will shrink quickly along the outer contour of the container and cling to the surface of the container. The heat-shrinkable label mainly includes shrink sleeve labels and shrink wrap label.
Shrink sleeve label is a cylindrical label made of heat shrinkable film as the base material and printed. It has the characteristics of convenient use and is extremely suitable for special-shaped containers. Shrink sleeve labels generally require special labeling equipment to cover the printed sleeve labels onto the container. First of all, the labeling equipment will open the sealed cylindrical sleeve label, sometimes it may need to punch holes; Next, cut the sleeve label into appropriate sizes and sleeve it on the container. Then heat treatment is carried out by using steam, infrared rays or hot air channels so that the casing label is tightly attached to the surface of the container. Due to the high transparency of the film itself, the label has bright color and luster. However, there is a defect of pattern distortion because it must be shrunk during use. Especially for products printed with bar code marks, strict design and printing quality control must be carried out, otherwise, the bar code quality will be unqualified after pattern distortion.
Shrinkwrap labels can be labeled with traditional labeling equipment, and adhesives and higher temperatures are required in the labeling process. In the shrinkage process, hot melt adhesive is preferred because the adhesive at the overlapping part of the film will produce stress effect.
However, the shrink label still needs to be improved. For example, it is necessary to consider the shrinkage rate of the graphic image as well as the shrinkage rate of the shrink film in order to accurately reproduce. The ink used in shrink label printing must also have a certain shrinkage rate in order to accurately reproduce images and texts. Because shrink labels must shrink in the printing process, and bar codes can only be read by accurate reproduction, they must go through strict design and printing quality control. Otherwise, after the pattern shrinks and deforms, the bar code will be unqualified or unreadable. The printability of most heat shrinkable film is not very good, so prepress pretreatment is needed.