Adhesive Label Quality Control (I)

Self-adhesive label printing belongs to special printing. In general, printing and post-press processing are completed on the labeling machine at one time, that is, multiple processing operations are completed on several stations of a single machine. Because of on-line processing, the control of the quality of self-adhesive labels is a comprehensive issue of printing and processing. Comprehensive consideration and implementation must be taken from the selection of raw materials, configuration and adjustment of equipment, and formulation of process routes, and tracking of label products. Application at the customer's place to further improve the quality of the label product.
First, the choice of raw materials When selecting raw materials, we must use high-quality, all physical and chemical indicators are qualified stickers, do not use expired or physical and chemical indicators of unstable products. Because the latter is low in price, due to the unstable quality of such materials, it consumes a great deal in various processes, and even leads to the normal processing of equipment. The waste of raw materials also wastes a lot of manpower and material resources, resulting in the processing of finished labels. The cost is not necessarily low, and even more severely punished is that customers may be returned or even lost.
The choice of raw materials should be considered from the following two aspects.
1. The printing and processing characteristics of self-adhesive materials (1) The surface gloss and color consistency of the surface material, and the uniformity of the density.
These indicators determine the uniformity of the ink-absorbing material of the self-adhesive material, and also determine the color difference of the same batch of label printing products. The coating strength of the face material determines whether a large amount of paper powder will be produced during printing, and is also an important indicator of the quality of printing.
(2) The uniformity of the thickness of the base paper and the surface material and the strength index.
These indicators are not only related to printing performance, but also an important indicator of die-cutting uniformity speed and edge breakage. If these indicators are too low, the labeler cannot produce at high speed.
(3) The flatness of the material or the uniformity of the rewind tension.
Whether it is single-sheet printing or web printing, the flatness of the material determines whether the paper can be fed correctly during printing, run and register, and take delivery. For reel material, the rewind tension will play an important role in the flatness of the end face of the reel material, the presence of glue penetration, and the correct registration.
(4) Adhesive, silicone oil coating uniformity and correct coating amount.
These indicators directly affect the peeling force (leaving force) between the endorsements and the backing paper. The size of the peeling force directly affects the speed of die cutting, waste discharge, and the machine. The peeling force also determines the labeling status, that is, the application situation. In addition, the amount of glue applied will also affect the condition of the glue on the end face of the material. Therefore, the purchase of adhesive materials should be carefully examined, and those materials with the right amount of coating and silicon coating should be selected.
2. Application characteristics of self-adhesive materials (1) Types of adhesive When choosing self-adhesive materials, the first thing to do is to determine whether the industrial mixture you need for the self-adhesive labels you make is permanent or removable. Whether it is a paste or reflowable, and whether the product has special requirements on the chemical properties of the label adhesive.
(2) Surface condition of the labeling object What kind of material is the surface of the labeling object, whether it is wood, glass or plastic, and whether the surface is smooth or rough, and this kind of index determines what kind of adhesive should be used.
(3) The shape and strength of the labeling object The labeling object is a plane or a curved surface, is a large diameter or a small diameter, is a single curved surface or a spherical surface, and the object is a rigid body or is compressible and deformable. These indicators have a direct relationship with the choice of surface materials and adhesives.
(4) The environment in which the sticker is used The environment in which the tag is affixed is whether it is outdoor or indoor, whether it is in a high or low temperature environment, and whether the environment is corrosive or dry or wet. Based on these indicators, matching facestocks and adhesives can be selected.
(5) The use of self-adhesive labels is manual labeling or automatic labeling. The method of labeling the label can determine the type of label material, the type of ink, and the printing method.
Second, the ink of the right choice The choice of ink from the ink's own quality, color and ink on the substrates of the wetting situation - that is, the adhesion of the ink fastness and other aspects to consider. Although there are many kinds of self-adhesive materials, their surface materials can basically be divided into paper, aluminum foil and thin film. At present in China, the printing of adhesive labels is mainly printed by embossing (web printing) and offset printing.
The paper surface material generally has no ink fastness problem, so the requirements for the ink are not high, and there is a certain degree of interchangeability and versatility with non-brand inks. However, due to the very strict surface tension requirements of aluminum foil and film materials, the following principles should be followed in selecting the ink: (To be continued)