The laminating film of the self-adhesive laminating machine is generally a transparent BOPP film laminated on a paper-based self-adhesive material, which can achieve the purpose of protecting the pattern, waterproofing, anti-corrosion, and increasing the three-dimensional sense of the label. Other types of films, such as PET and PVC, can also be used as composite films, but their applications are not universal. Due to the high cost of paper roll material coating, it has been gradually replaced by UV coating process.
        1. Laminating method of self-adhesive laminating machine
        The self-adhesive laminating machine is divided into sheet paper laminating and roll material laminating according to the printing process of raw materials. The sheet of paper is laminated on the laminator. The roll material is compounded on the compounding station of the labeling machine or on a special compounding machine.
        1. Sheet paper laminating
        According to the function of the laminating equipment and the characteristics of the composite film, there are two laminating methods for single-sheet self-adhesive labels:
        Instant coating compound-finish on laminating machine. The compounding process is: firstly, the adhesive is coated on the surface of the BOPP film on the roll, and the solvent in the adhesive is volatilized by the drying device, and then the single sheet of paper is compounded with the roll film at the compounding station. The two become one under the squeeze of the roller to complete the coating process.
        Pre-coated film composite-The surface of the composite film is pre-coated with adhesive, and there are two types of films, hot melt adhesive and pressure sensitive. The laminating machine is equipped with a heated embossing roller. When laminating, the pre-coated film is in contact with a single sheet of paper. Under the action of the hot pressing roller, the adhesive melts, so that the film and the paper are bonded together. If a pressure-sensitive composite film is used, the heating power can be turned off, and only pressure is used for composite.
        2. Roll paper laminating
        According to the different equipment, roll paper film can be divided into:
        Composite film with bottom paper is used for lamination-on the labeling machine, a special composite film with bottom paper is used, and the film is covered under the action of a composite device. This is a traditional way of laminating. In recent years, it has been replaced by the process of using bottomless paper composite film.
        Bottomless paper composite film lamination-carried out on the labeling machine, the principle of lamination is basically the same as the bottom paper composite film lamination process. The bottomless paper film is rewinded to replace the bottom paper by the surface smoothness (surface tension) of its own material. After the adhesive is bonded to its surface, it can be peeled off without leaving any adhesive marks. The material used in the bottomless paper film is a BOPP film with low surface tension. Bottomless paper film has low cost and is currently the most widely used lamination material.
        Dry laminating-carried out on laminating machine or gravure printing machine, mainly used for laminating film materials. The dry laminating film of the roll material is suitable for mass label products, with good film quality and low cost. After the roll label is coated, the secondary processing such as die-cutting and waste discharge is usually carried out on the processing machine, such as some battery labels and wine labels.
         UV coating process-the latest foreign technology, mainly used in the unit type rotary label machine with UV drying device. The process principle is: the surface of the film material is first printed with a UV adhesive by a common printing unit, and the adhesive becomes a pressure-sensitive adhesive after being cured by a UV drying device. Then the ordinary BOPP film (the general composite surface has been corona treated) is compounded with the reel material at the laminating station to complete the laminating process. The cost of UV coating is low, the tension of the composite film is small, no special film is needed, and it is suitable for high-speed production. UV coating is a promising process and has been applied in developed countries in Europe and America.
        2. Technical requirements of self-adhesive laminating machine
        There are many factors involved in the coating process. It is necessary to understand the impact of various process parameters on the quality of the coating, and correctly handle the relationship between them to achieve the best results. The technical parameters and precautions involved in the laminating process are as follows:
       1. Drying temperature-control between 50 ~ 70 ℃, not only can fully volatilize the solvent, but also will not cause the film to overheat and deform;
        2. Compounding temperature-the temperature of the impression cylinder is controlled at 70～90℃, which can melt the adhesive and the film will not be deformed by overheating;
        3. Compound pressure-ensure that the axial pressure of the impression cylinder is consistent, and the pressure should be kept within 150-250 kg/cm²;
         4. Adhesive coating-the coating should be thin, control at 3-8 g/cm², and the thickness should be 5-8μm, avoid excessive coating;
        5. Machine speed-single paper should be controlled at 35～45 sheets/min, web paper should be at 3～10m/min, and it is also related to other parameters;
        6. Film tension-adjust the tension to the lowest level to achieve the correct coating and compounding, and avoid excessive tension;
        7. Cylinder precision-The surface of the impression cylinder is required to be smooth and clean, without scratches and pits. It is necessary to ensure mechanical accuracy indicators such as ellipticity and concentricity;
        8. Environmental factors-keep the environment clean and require air purification devices. Control the temperature and humidity of the workshop to prevent the deformation of paper or film;
        9. Ink thickness-deep ink and shallow printing are required to avoid excessively thick ink layer causing a drop in surface tension and weakening of the film;
        10. Ink drying-the ink should be dried thoroughly to avoid blistering;
        11. Ink additives-control the amount of desiccant to prevent crystallization of the ink layer. The surface of the crystalline ink will have a weak film.
        As long as you correctly understand and understand the principle and process of the self-adhesive printing ink brushing process, comprehensively consider the various conditions and reasons that affect the quality, and take corresponding technical measures, you will surely be able to print out the various products that the market welcomes. Rubber prints.