PUR products are divided into two categories: foaming products and non foaming products. PUR materials have excellent properties, wide uses and many kinds of products, especially PUR foam plastics. The physical structure layer of PUR hot melt adhesive machine system is specific and three-dimensional. The specific and three-dimensional structure can be regarded as a combination of multiple modules and form the overall layout of the hot-melt adhesive composite machine system.
The combination of PUR hot melt adhesive machine is too complex or the pressure on the two ends of the compound roller is not uniform. It will cause wrinkles on the surface of the composite membrane and form an empty tunnel at the end of the composite ruffles, which will affect the fastness of the finished products. The effective way to solve this problem is to increase the amount of coating, appropriate drying temperature, and increase the pressure of the compound properly.
(1) to increase the amount of coating, the amount of coating is too little or the surface of the substrate is not coated with adhesive, which will lead to the hard bonding of the two substrate when the composite is composite. We can choose the deeper web roller or increase the rubber roller pressure and reduce the contact pressure between the scraper and the anilox roller to increase the amount of glue on the surface of the substrate. For some plastic film substrates, corona treatment can be made before coating, so that the surface of HP can be increased, so as to improve the ability of base material to adsorb adhesives and increase the amount of glue on its surface.
(2) the choice of appropriate drying temperature is too high or too low, which will affect the bonding fastness of the composite film. When the coating substrate is too hot to be heated or steamed through high temperature, the surface of the adhesive will be carbonized, which destroys the bonding ability of the adhesive. When the drying temperature is too low, the information of the manufacturer is incomplete, the viscosity of the adhesive is poor, and the adhesive is not firm. After a period of time, the composite film is easy to form bubbles and destroy the compound quality of the product. Of course, we can choose a high temperature and good steaming adhesive digital printing machine to adapt to high temperature drying, such as the use of polyurethane adhesives.
(3) increase the compound pressure appropriately, the compound pressure of the compound machine is too large or the pressure of the two ends of the compound roller is not uniform, which will cause the surface wrinkle of the composite membrane, and form an empty tunnel after the compound ruffle, which will affect the fastness of the finished product. The compound pressure can be improved by increasing the compound pressure properly. In addition, in order to improve the bonding effect and quality of the composite film, we should avoid impurities such as foreign matter and dust on the adhesive or substrate composite surface. In the end of the operation, we should carefully observe the various problems and failures in the production process, and use the above method to eliminate the failure. When there are a number of problems or failures, a single method may not be taken into consideration, and it should be avoided at this time.
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