Discussion and Research on the Outer Film Coating Process of PP Woven Bags

Laminating, also known as coating, lamination, or film application, refers to the process of applying a transparent plastic film to the surface of printed materials through heat and pressure. This provides protection against moisture and enhances gloss. Laminating is widely used for surface protection of woven bags, book covers, albums, commemorative albums, postcards, product manuals, calendars, and maps. Currently, common laminated packaging products include Pp Woven Bags, cartons, paper boxes, tote bags, fertilizer bags, seed bags, and self-adhesive labels.

Laminating in Plastic Woven Bag Packaging Printing

Woven bag laminating is a selective reprocessing technique after the woven fabric has been woven. It involves bonding a plastic film coated with adhesive to the woven bag under heat and pressure, forming a double-layered plastic composite product. It is a common reprocessing technique used to enhance the moisture-proof properties of woven bags and is performed before the printing process. Laminated Woven Bags have a smoother, shinier surface due to the added thin, transparent plastic film. This not only enhances the bag's gloss but also provides protection against moisture, water, stains, abrasion, folding, and chemical corrosion. However, due to the inherent quality of the woven bag, high-pressure lamination doesn't significantly improve its weight or thickness. In fact, the high-pressure lamination process slightly weakens the bag's tensile strength, making the laminated bag feel slightly stiffer and less soft than the unlaminated one. From a pre-printing perspective, using a transparent, glossy film results in more vibrant and three-dimensional colors in the printed images, making it particularly suitable for packaging products like organic food, stimulating appetite and consumer desire. Using a matte film gives the product a more sophisticated and elegant feel. Therefore, laminated packaging significantly enhances the grade and added value of product packaging.

The lamination process requires production personnel to apply appropriate processing temperatures and pressures based on the properties of the Woven Bags and inks, ensuring the adhesive firmly bonds the plastic film and Woven Bag together. Quality standards for laminated products include: a clean, smooth, and clear surface; good gloss; no wrinkles or bubbles; no separation between the Woven Bag and the outer film; and no powder residue. The product should be properly dried, without damaging the surface film or Woven Bag. By carefully managing the temperature, pressure, and time during the hot-pressing process, and controlling factors such as adhesive consistency, amount, oven temperature, hot roller temperature, mechanical pressure, and mechanical speed during the fusion stage, problems such as bubbling and weak adhesion can be avoided during lamination.