Printed water coating process

As we all know, the printed film is one of the printed surface finishing technology, and it is an auxiliary process of printing. It is the plastic film bonded to the printed material through the adhesive to achieve the effect of improving the glossiness, strength and aesthetic effect of the printed surface. The purpose is to make it water-resistant and wear-resistant, which is an effective means to improve the quality of printed materials and commodities. Therefore, the merits of the quality of the coated film are mainly examined from the aspects of brightness, strength, and adhesiveness of the product.

For the laminating process, it mainly uses two types of materials: film and adhesive. Films used for laminating mainly include biaxially-stretched propylene film (BOPP), polyvinyl chloride (PVC), etc. Among them, BOPP film is most widely used. The adhesives used in the film can be divided into oily film glue and water-soluble film glue. For water-based glue, EVA resin (ethylene vinyl acetate copolymer resin), acrylic resin, etc. are the most commonly used in production; in terms of its chemical structure, there are single-component and two-component products.

Since the development of the water-based laminating machine in the 1990s, the water-based laminating technology has been promoted and applied. The water-based laminating film has been favored by customers because of its features of high brightness, high grade, easy recycling, and no pollution. Ever since its establishment in 1995, Hengtai Color Printing Co., Ltd. has produced many water-based film-coated products such as wine boxes, wine boxes, wine labels, handbags, and posters. The process of water-based film coating has also accumulated some experience. Here, we will discuss with you through the following aspects:

1 Printing dusting

Because water-based glue can dissolve powder on the surface of printed products, it is incomprehensible when the film product has snow flakes. In fact, the reason is simple. Water-based glue itself is also limited by its solubility. When the amount of powder sprayed on the printed matter is greater than the ability of the glue to dissolve, the excess part cannot be dissolved or covered by the glue, and there will be a large amount of snow spots. In this case, there are several solutions:

First, coordinate the process up and down, minimize the amount of dusting during printing. In our company, there are Roland, Heidelberg two types of machines, because the dusting device and the organization is not the same, for the same product, Roland computer machine than the Heidelberg machine in the spray evenly to some control.

Second, in the film, the appropriate increase in the amount of glue, to increase the ability of glue dissolved powder spray. In actual production, the maximum amount of glue to be glued is the maximum amount of glue when the edge of the product does not overflow.

Third, the surface of the printed matter is sprayed and dusted before the film is coated. The surface may be wiped by hand or other powder removing devices may be provided on the machine.

2 Cleaning

Because the water-based film glue dries quickly, if it does not flow and it is exposed to the air for too long, it will dry the crust and attach it to the coating roller or pressure roller, resulting in local coating or glue layer being too thin At the same time, the local pressure is increased, so the coating roller and the pressure roller should be kept clean during the film coating process. In addition, there is too much dust in the surrounding environment or there is dry rubber and cut film fragments in the glue. Can also affect the quality of the film, so be sure to pay attention to cleanliness, pay attention to the glue storage, can be added in the actual and production process of glue filtration device.

3 Paper release

Paper detachment phenomenon is easy to appear in the printing area is relatively large and large field products, because the surface of the ink layer is thick, the glue is difficult to wet, diffusion, penetration, and thus the bond is not strong. The solution is:

First, check the glue production date and shelf life to see if the glue is deteriorating.

Second, the film is in the shelf life, the surface corona value is how much.

Third, with reference to the technical indicators of glue, in the actual production whether the correct operation in accordance with the regulations.

Fourth, replacement of other brands of large viscosity glue.

Fifth, improve the humidity of the film and the product when it is dry.

4 Deformation

There are several reasons for the deformation:

First, the amount of glue is too large, the paper absorbs moisture and deformation, so in the premise of ensuring product quality, should minimize the amount of glue.

Second, the film tensile deformation is serious, this time should be properly adjusted to the film's loose tension, in ensuring the film is flat with the paper fit, the smaller the tension the better.

Third, the winding tension is too large, this time according to the circumstances, in ensuring the product is delivered to the roller, the tighter the better.

Fourth, the temperature and humidity of the external environment where the product is located vary greatly.

In general, with the rapid development of the printing and packaging industry, continuous innovation in technology and the emergence and replacement of new materials, we will also face new problems and new challenges. Hang Tai Color Printing will also keep pace with the times to seek higher development.

Reprinted from: China Design Printing Network