Coating a printed paper product with a transparent plastic film is called lamination. The production principle of lamination: First, the adhesive is applied to the film through a roller coating device, and then heated by a hot pressing roller to soften the film. Then, the printed matter coated with the substrate is pressed and pressed together with the film to form a lamination product that combines the two.
Like album printing, the cover and the outside of the packaging box in brochure printing are easily worn out. In order to improve the surface gloss and use effect of printed products, film covering is a process frequently used by Yingli Printing Factory. This process is applicable to various commodity packaging, which can protect and beautify products and improve their value.
During the process of product lamination in a printing factory, the most common problem is that the product film does not adhere firmly to the printed matter, which is prone to blistering or peeling off, which affects the beauty and use of the product. To completely solve this problem, printing needs to be considered in combination with ink and printing technology.
The lamination process is generally relatively simple, using adhesives to bond printed matter and film together. The porous and porous structure on the surface of printed matter is conducive to the penetration and diffusion of adhesive, and the ink in the graphic and text areas of printed matter is the main reason for the poor adhesion of printed matter to the film.
The impact of ink on the film covering effect is mainly the effect of the surface properties of the ink after drying on the adhesive. When the ink dries, the main component of the surface layer is the ink diluent, which may also contain some other substances. For example, 1. The powdery particles in the white ink component will float on the surface layer of the ink due to insufficient binding force with the binder, and then dry; 2. The aluminum hydroxide in the Villi oil component also floats on the surface of the ink due to its light weight; 3. The film forming resin, which is a component of the bright paste, can improve the film forming effect of the ink, and is also located on the surface of the ink.
When laminating, the white ink pigment particles on the surface of the ink layer will hinder the adhesive and affect its further penetration on the surface of the printed ink layer; The aluminum hydroxide in Villi oil is prone to form an isolation layer, hindering the interaction between the adhesive and the ink layer, leading to blistering or poor adhesion; Brightening paste is beneficial for film covering, with similar composition and adhesive properties, and good affinity. Therefore, when adding ink diluents, comprehensive consideration should be given to the film covering effect of the product. The particle size of the ink can also affect the film covering effect. If the particles are too large, it will affect the bonding effect between the film and the printed surface, which can easily lead to blistering and poor adhesion. In particular, gold and silver ink is not suitable for laminating products printed with gold and silver ink because metal pigment particles will separate after the ink dries, impeding the mutual bonding of the ink layer and the adhesive.
Printed matter needs to be completed through printing. As mentioned above, the surface performance of the dried ink can affect the film covering effect, and under the premise of using appropriate ink, factors such as printing format, ink layer thickness, and drying effect can also cause poor adhesion of the film covering. If the printing format is too large, it will reduce the contact area between the paper surface and the adhesive, exacerbating the decline in the adhesion effect between the printed surface and the adhesive, and greatly reducing the quality and service life of the coated product. Therefore, it is necessary to avoid laminating large format or field printed products. If the printing ink is used too thick, the blocking effect on the adhesive will be increased, which will directly cause delamination and further failure to adhere. Comparing the characteristics of the ink layer obtained by various printing processes, offset printing has the lowest ink layer thickness, ranging from 1 to 2 μ m. Therefore, it is best to choose offset printing for prints requiring film covering, and pay attention to controlling the overprinting effect of color printing and the final ink layer thickness of the print.