Self-adhesive labels are usually coated with transparent BOPP film on paper self-adhesive materials. BOPP labels(PRINT-LABELS) can achieve the purpose of protecting pattern, waterproof, anti-corrosion and increasing the stereoscopic impression of labels. Other types of films, such as PET and PVC, can also be used as composite films, but their application is not common. Due to the high cost, the coating of paper roll materials has been gradually replaced by UV glazing technology.
Self-adhesive labels are divided into single-sheet coated paper and roll coated paper according to the printing and processing methods of raw materials. A single sheet of paper is coated on a laminating machine. The reel material is compounded at a compounding station in labeling machine or a special compounding machine.
1. Sheet-fed laminating
According to the functions of the laminating equipment and the characteristics of the composite film, there are two laminating methods for single-sheet self-adhesive labels:
That is, coating and compounding-completed on a laminating machine. The compounding process comprises the following steps of: firstly, coating an adhesive on the surface of a drum BOPP film, volatilizing solvent in the adhesive through a drying device, then compounding a single sheet of paper with the drum film at a compounding station, and extruding the sheet of paper and the drum film into a whole under a hot drum to finish the laminating process.
Pre-coated film compounding-the surface of the composite film is pre-coated with adhesive, and there are hot melt adhesive and pressure sensitive films. The laminating machine is equipped with a heating impression cylinder. When laminating, the pre-coated film contacts with a single sheet of paper. Under the action of a hot-pressing roller, the adhesive melts, making the film and the paper adhere into a whole. If a pressure sensitive composite membrane is used, the heating power supply can be turned off, and only pressure compounding is used.
2. Web laminating
According to the different equipment, web coating can be divided into:
Composite film compounding with bottom paper-it is carried out on a labeling machine, using a special composite film with bottom paper and covered with film under the action of a compounding device. This is a traditional film covering method. In recent years, it has been replaced by the process of using bottomless paper composite membrane.
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