Lamination is one of the main processes for the cover of book printing. It is a kind of product which combines the plastic film coated with adhesive. And the paper printed matter after heating and pressurizing to form a paper plastic integrated product. It is one of the common processes of book printing matter at present.
Lamination process is mainly divided into semi-automatic operation and full-automatic operation. Although there are some differences between semi-automatic and full-automatic in the specific operation. The principle is the same: first, the adhesive is coated on the plastic film through the roller coating device. And then the film is softened by the heating of the hot pressing roller. And then the printed matter coated with the substrate and the film are pressed together to form a paper plastic integrated coated product.
According to different classification of raw materials and equipment used
According to the different raw materials and equipment. The lamination process can be divided into two parts: coating process and pre coating process. These two processes are mainly solvent-free hot melt adhesive pre coating dry composite process and emulsion adhesive wet type instant coating process. Solventless hot-melt adhesive pre coating dry-type composite has been condensed into a single hot pressing process, which is widely used in China at present. The core technology of wet adhesive coating process is mainly composed of three aspects: coating, cold pressing and drying. The difference between them is that the coating type is directly pressed after the adhesive is coated and the two pre coating types are dried and then hot pressed after the adhesive is coated.
Classification according to the lamination process of paper printing
According to the laminating process of paper printing, the laminating process can be divided into three categories: dry laminating, wet laminating and pre laminating。
1. Dry laminating
Dry laminating is the most commonly used laminating method in China. It is to coat a layer of adhesive on the plastic film, then evaporate the solvent in the adhesive through the drying and drying channel of the laminating machine, and then dry it, and then glue it with the paper print under the hot pressing state to synthesize the laminating product.
2. Wet laminating
Wet laminating method is to coat a layer of adhesive on the surface of plastic film. Under the condition that the adhesive is not dry, the laminating product is synthesized by bonding the press roll with the paper printed matter. Since the advent of the water-based laminating machine, the water-based laminating process has been popularized and applied, which is inseparable from the characteristics of the wet laminating process, such as simple operation, small amount of binder, no organic solvent damaging the environment, high strength, high grade and easy recovery of the coated printed matter. At present, the coating technology is more and more popular with domestic packaging manufacturers, and has been widely used in gift boxes and handbags and other packaging.
3. Pre coating
The pre coating and laminating method is that the laminating manufacturer directly purchases the pre coated plastic film with adhesive. When laminating is needed, the film and paper printed matter are hot pressed together on the laminating equipment to complete the laminating process. The technology of pre coating and laminating began in 1990s. Through the special equipment, the hot melt adhesive or low temperature resin is uniformly coated on the film substrate according to the design, and the pre coating is obtained. The pre coating and laminating method can eliminate the process links such as adhesive deployment, coating and drying. We can complete the whole laminating process in a few seconds, which will not pollute the environment, have no fire hazard, and do not need to clean the coating equipment. At present, the technology has been used in the field of medicine and food packaging.