Lamination refers to the application of transparent plastic film to the surface of printed matter by hot pressing to protect and increase gloss. It is widely used in various industries because of its durability and aesthetics, such as book covers, postcards, packaging boxes, brochures and so on. Among them, lamination is also an important process in the manufacture of self-adhesive labels. It helps to improve the label’s abrasion resistance, water resistance, dirt resistance, chemical corrosion resistance and other properties.
However, a common challenge in the lamination process is the occurrence of wrinkling and air bubbles in the film, which can affect the quality and functionality of the label. In this article, we’ll explore the causes and solutions to the problem of wrinkling and brittle laminations, ensuring a flawless finish to the required standards.
Optimizing substrate selection:
Some film materials have quality defects when they leave the factory, with bubbles or small wrinkles in themselves. Most of these bubbles occur on the glue of the film itself, which are often difficult to find with the naked eye. When encountering such defective raw materials, they should be checked frequently during the production process, and the materials should be found and replaced in time to avoid increasing material loss. Enterprises with conditions are recommended to install online automatic testing equipment to check product quality and find and deal with problems in a timely manner. Inspection and conditioning of the material prior to lamination work can minimize the risk of wrinkling. Poor quality or damaged material may cause wrinkling problems. Replace any defective components to ensure smooth lamination.
Control moisture content:
Moisture is a major contributor to wrinkled and brittle labels. Moisture or humidity in the environment can affect the lamination process. If the film or substrate absorbs moisture, it can swell or shrink unevenly, causing wrinkles during lamination. Both substrate and laminate should be stored in a dry environment to prevent these problems. Substrates should be stored in a controlled environment to maintain their moisture balance. Likewise, laminating materials, such as adhesives and films, should be stored and handled properly to prevent moisture absorption. Regular monitoring and testing of moisture levels helps ensure optimal conditions for the lamination process.
Maintain proper lamination temperature:
Paper and plastic film are compounded by hot pressing. Controlling temperature during lamination is critical to successful results. Lamination equipment should be calibrated and maintained to ensure precise temperature control. Too high a temperature will cause the adhesive to become too thin and cause over-extrusion, while too low a temperature will prevent proper bonding. Regular monitoring and adjustment of lamination temperature based on the specific lamination material being used can help avoid problems with film wrinkling.
Consider tension magnitude:
Uneven tension during lamination can cause the film to stretch or shrink unevenly, resulting in wrinkles. The uneven tension here may be a problem with film materials, printing materials, or printing equipment. Once this happens, it is easy to cause the film to fold, and it is a relatively obvious large fold. We need to adjust the equipment or replace the material to solve it. Make sure the laminator is properly calibrated to maintain even tension and even pressure on the film. Regular maintenance and machine adjustments can help prevent wrinkles.
Press roller maintenance:
Most self-adhesive label lamination materials are extruded on the surface of printed materials by silicone or polyurethane rollers. If the pressure roller is uneven, it will cause uneven pressure on the composite film. Insufficient pressure can lead to poor bonding and air trapping, which can lead to weakness and wrinkling. On the other hand, too much pressure can deform the label or cause the adhesive to over-extrude. The folds caused by this situation are generally large and easy to detect with the naked eye. We can balance the pressure at both ends of the pressure roller by adjusting the springs at both ends of the pressure roller. In addition, when the composite roller is found to be aging or has hard damage on the surface, it may also cause small air bubbles or folds. In this case, the composite roller should be replaced in time.
Implement proper handling and storage:
After the lamination process is complete, proper handling and storage of laminated labels is critical to prevent wrinkling and brittleness. Labels should be allowed sufficient time to cure and set before further processing or packaging. Proper stacking and storage techniques should be used to prevent any stress or bending that could cause deformation. Providing adequate protection from moisture, heat and direct sunlight will help maintain the integrity of the laminated label.
Quality control and inspection:
Implementing a robust quality control system is critical to identifying and correcting any issues with laminated labels. Periodic inspections should be performed at all stages of the lamination process for any signs of wrinkling, blistering or other defects. An automatic inspection system can be employed to ensure consistent quality and minimize human error. Any defective labels shall be identified and corrected promptly to maintain the required standard.
Lamination film wrinkling during label lamination can be attributed to several factors. Wrinkling problems can be mitigated by considering the quality of the film, controlling tension, maintaining pressure rolls, and controlling temperature and humidity. Selecting a high-quality film, ensuring proper machine alignment, maintaining pressure rollers, and creating a controlled lamination environment are critical steps in achieving smooth, perfectly laminated labels. By paying attention to these factors and continuously improving your lamination process, you can improve the overall quality and appearance of your labeled products.
