Coating technology is widely used in the coating of paper and film substrates and composite packaging. At present, many domestic printing and packaging machinery companies use coating compound equipment, the coating type and squeegee method are relatively single, and the application of coating technology is also greatly restricted. No matter what kind of coating compound equipment, the key part is the coating head, and the coating method used by the coating head will directly affect the quality and effect of coating.
Type and application of sizing
Coating compound equipment is mainly used for sizing and compounding of various reel base materials such as plastic film, paper, anodized aluminum, cloth and leather. It is widely used in various packaging fields and has broad development prospects. The coating compounding equipment is roughly divided into three types: glue coating on the optical roller, glue coating on the anilox roller and hot melt adhesive spray coating.
Smooth roll coating
This sizing coating usually uses two-roll transfer coating. By adjusting the gap between the upper rubber roller and the coating roller, the amount of coating can be adjusted. The structure of the entire coating head part is relatively complicated, requiring high processing precision and assembly precision of the glue roller, coating roller, traction roller and scraper, and relatively high cost. Because this coater mainly uses high-precision smooth rolls for sizing coating, the coating effect is better. The amount of coating is not only adjusted by the gap between the sizing roll and the coating roll, but also by coating. The micro-adjustment of the doctor blade can be controlled flexibly, and the coating accuracy is high. At present, it is also the most widely used in coating compound equipment.
Anilox coating
This type of coating equipment mainly uses anilox (concave) coating rollers for sizing coating. The coating is uniform, and the coating amount is relatively accurate (but the coating amount is difficult to adjust). When coating with an anilox roller, the coating amount is mainly related to the depth of the concave eye of the anilox roller and the accuracy of the type of glue. The deeper the depth of the anilox roller, the more the amount of glue transferred from the concave hole to the substrate; conversely, the shallower the depth of the anilox roller, the smaller the amount of transferred to the substrate. It also has a lot to do with viscosity. The viscosity of the glue is too large and too small are not conducive to the normal transfer of glue. The viscosity of the glue is not easy to transfer, and too thin is easy to flow, making the glue uneven, and it is easy to produce vertical or horizontal watermarks. Therefore, once the types of the anilox roller and the glue are fixed, it is difficult to adjust the coating amount, which is the main reason why the application of the anilox roller is limited.
Hot melt adhesive spray coating
This kind of coating equipment mainly melts the solid type glue by heating, and sprays the glue directly on the substrate through the coating die by hydraulic loading. Hot-melt adhesive coating is a new technology developed in the past ten years. Hot-melt adhesive coating does not require drying equipment and has low energy consumption; hot-melt adhesive is 100% solid adhesive composition and does not contain toxic organic solvents. The common glue coating mostly uses toxic organic solvents (such as benzene, etc.) to dilute the glue, and the poisonous gas caused by it is extremely harmful to the operators. Hot melt adhesive coating has its unique advantages compared with ordinary sizing coating. Hot melt adhesive coating is a green and environmentally friendly coating technology. It has fast production speed, high efficiency, low cost, small equipment footprint, and short investment recovery period. It is an economical investment project and has been widely used in packaging. , Medicine, automobile, clothing, electronics and other industries. Hot-melt adhesive coating has huge market development prospects, the development ratio of this technology in the market will be larger and larger, and new application fields will continue to appear.
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