The influence of the ink layer condition of printed products on the laminating quality of laminating machines

The ink layer condition of printed products mainly refers to the properties of paper, ink performance, ink layer thickness, image surface, and printed image integral density. Their influence on the laminating quality is mainly the influence on the bonding strength between printed products and films.

1. Ink layer thickness. When the ink layer of printed products is thick and the image area is large, these inks change the porous surface characteristics of the paper, close many paper fiber pores, hinder the penetration and diffusion of adhesives, make it difficult for printed products to bond with plastic films, and easily cause delamination, bubbles and other faults.

2. The role of ink diluents. Commonly used ink diluents include white ink, Willy oil and gloss paste. Among them, white ink has obvious powdery particles, which are not tightly combined with the binder. After printing, these pigment particles will float on the paper surface, which will hinder the bonding. Willy oil is rolled from aluminum hydroxide and binder. Because aluminum hydroxide is light, it often floats on the surface of the ink layer after printing. During lamination, an isolation layer is formed between the adhesive and the ink layer, resulting in poor bonding or bubbles. The glossy paste is made of resin, dry vegetable oil, drier, etc. It has a fine texture and bright film. It has similar properties to the laminating adhesive with conjugated multi-bond terpene resin as the main component. They have good affinity and can firmly adsorb the polypropylene film on the surface of the ink.

3. Adding dry oil. Adding dry oil to the ink can accelerate the drying of the print, but a large amount of dry oil will easily form a shiny and smooth low interface d layer on the surface of the ink layer, making it difficult for the adhesive to wet and penetrate, affecting the fastness of the lamination. Therefore, the amount of dry oil added should be controlled.

4. Powder spraying. Offset printing uses the process of powder spraying to avoid the print from being stained, and a layer of fine particles is formed on the surface of the powdered ink layer. During lamination, the adhesive is not bonded to the ink layer everywhere, but to these powders, forming a false adhesion phenomenon, which seriously affects the quality of lamination. Therefore, for products to be laminated, powder spraying technology should be avoided. For printed products that have been powdered, dry cloth should be used to wipe off the powder one by one.

5. Gold and silver ink prints. Gold and silver ink is made of metal powder and binder. The distribution uniformity and fixation of these metal powders in the binder are very poor, and the ink layer is easily separated during drying. These separated metal powders form a barrier between the ink layer and the adhesive layer, affecting the effective bonding of the two interfaces. After this product is placed for a period of time, wrinkles and bubbles will appear. Therefore, the lamination of gold and silver ink prints should be avoided.

6. Drying condition of the ink layer of the printed product. When laminating when the ink is not completely dry, the high boiling point solvent contained in the ink can easily swell and elongate the plastic film, which is the main reason for bubbles and delamination of the product after lamination. The full drying of the ink layer is the primary condition to ensure the quality of the ink layer. For products that are not dry and need to be inked urgently, they can be dried.