(1) Comprehensive considerations based on the type, grade, quality, characteristics of the surface to be pasted, the environment of use, and the requirements of the user. If a label made of a transparent polypropylene sticker is applied to a transparent bottle, it can produce a label-free fashion feeling, which can improve the quality of the product and stimulate the consumer's desire to purchase. The flexibility, shrinkage, opacity, processing characteristics and labeling properties of the polyvinyl chloride film are very good, and the color is bright, which has the function of promoting promotional items.
(2) The surface of the film-type self-adhesive label must be smooth and compact, uniform in density, uniform in color and good in light transmission, so as to ensure uniform ink absorption and small color difference of the same batch of printed products.
(3) The thickness of the self-adhesive label should be uniform and the strength index should be qualified. The printing pressure applied during the printing process is related to the thickness of the sticker. If the thickness is uneven, the printing pressure is not uniform, which may cause the writing or the ink color of the label print to be deep and shallow. If the film strength is too poor, the tension of the film during printing is difficult to control, which has a great influence on die cutting and waste discharge.
(4) The self-adhesive label should be flat and the rewinding tension should be uniform. The flatness is good, and it can be correctly transported, operated, registered and wound up during printing. The rewinding tension of the film should be uniform and appropriate. For example, the tension is too small, the film substrate is slack, and the vertical and horizontal overprinting is not accurate; if the tension is too large, the substrate shrinks laterally, the color registration is unstable, and it is difficult to print normally.
(5) Membrane adhesive labels must also have corrosion resistance, aging resistance, no fading, shrinkage, and low expansion ratio. If the corrosion resistance is poor, easy to aging, fade, the resulting label is not durable, and will affect the sale and use of the product. If the shrinkage and expansion ratio are large, it not only affects the overprinting accuracy during printing, but also causes the label to be deformed during use, which affects the sale and use of the product. In particular, labels for high-end goods should try to avoid the embarrassing situation in which the products have not expired, and the labels have deteriorated (label aging includes plastic aging and ink fading, etc.). If necessary, anti-aging tests should be carried out on plastics or labels to test their performance.
(6) The optional self-adhesive label should also maintain good adhesion during the validity period.