Analysis of the causes of the most popular film co

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Analysis on the causes of dull and blistering of coated prints

part of the coating method of color packaging is to use biaxially oriented polypropylene film, and the coated products will appear dull or blistering. The author has studied and analyzed this problem. The tensile force required for the fracture of the total heat sealed specimen under the action of tensile force leads to the following points

1 improper temperature control

when coating different substrates, the temperature of the electrically heated steel drum must be adjusted according to the covered products. If the film coated substrate 102 petroleum asphalt is gold card paper, the temperature of the steel roller should be controlled at 70 ~ 80 ℃; If it is covered with 250g/m2 or 300g/m2 gray paper, the temperature should be adjusted to 80 ~ 90 ℃. Whiteboard absorbs much more water than gold card paper during placement. Especially in rainy days and winter, if the temperature is not adjusted properly, the coated products will not be bright. When laminating, it is sometimes found that there are obvious drops of water or steam on the silicone drum, which is caused by the paper absorbing a large amount of water. The film covering temperature of such products must be increased. For general products, the temperature of the drying channel can be controlled at 50 ~ 60 ℃, and the glued film can be used to stick it with fingers at the exit of the drying channel without obvious traces, and it can be a little sticky. If the coating temperature is adjusted too high, it will blister. Therefore, the temperature of the heating steel drum must be controlled according to the product characteristics when laminating

2 insufficient pressure

according to the needs of customers, the thickness of substrate materials is mostly inconsistent. In order to speed up the technological progress, the pressure between the silicone drum and the steel drum should be adjusted according to the thickness of the substrate paper. If the pressure is too small, the film of the coated products is not firm, not bright, and easy to wrinkle, said Yang Jie, vice president of the Automotive Materials Engineering Research Institute of the technology center of Great Wall Motors Co., Ltd; Too much pressure will cause membrane wrinkles and paper deformation

3 glue output

when using stretched polypropylene film for coating, glue must be applied to the film. The amount of glue is applied on the moving film by rotating a transmission steel roller installed in the glue box. The control of the amount of glue is controlled by a steel blade falling on the steel roller. Light pressure and large glue quantity; The pressure is heavy and the amount of glue is small. The amount of glue should be well controlled, which can cover firmly and evenly without crystal points. If the amount of glue is too large, the covered product will also have no luster

in the process of gluing, special attention should be paid to prevent small particles and foreign matters after glue solidification from remaining in the glue tray. If there is something left, it will be taken up by the rubber roller during rotation and stuck on the rubber blade, and a glue free white print will appear here. Therefore, after a long-term shutdown of the laminating machine, before the laminating machine is started, the glue pump and the glue bucket box should be cleaned with laminating water or high boiling kerosene to ensure that the glue on the rubber roller is normally coated on the film without marks

4 keep the drum clean

after a long time of pressing, the steel drum will be in direct contact with the membrane, and with the effect of temperature, some debris will be left on the steel drum. The silica gel roller is directly in contact with the back of the paper of the covered product, coupled with the separation of the paper spacing, a lot of glue is directly pressed on the glue roller to produce accumulation, which will affect the brightness of the covered product. In serious cases, it will also wrinkle the covered products. Therefore, we must keep the drum clean and shut down at any time to ensure the quality of coated products

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