Laminating process of paper products (3)

UV glazing common problems and solutions


UV Varnish Common Problems and Solutions Common Problems Cause Analysis Improvement Countermeasures Gloss is not good, brightness is not enough The gap between the pressure roller and the coating roller is too small, the coating is too thin and the gap between the two is adjusted. Ethanol and other non-reactive solvents are diluted in excess to add some original Barrel UV Varnish Into the paper Absorption is too strong can be the first base and then UV Varnish coating roller is too thin, the amount of oil is insufficient Replace the coating roller Varnish itself is poor quality Replace with the new Varnish is not completely cured, Viscous UV lamp aging surface, strength weakened in time to repair equipment or replace the lamp, general UV oil curing radiation intensity required is not less than 25mW/cm2 UV Varnish storage time is too long Replace Varnish non-reactive diluent Add Too much adjustment of the UV oil concentration Machine speed is too fast Slow down Machine speed UV light oil on the surface of the print can not be painted, the flower UV light oil viscosity is small, the coating is too thin to adjust the viscosity, adjust the machine thickening coating ink containing the varnish Or too much dry oil can be the first base and then UV oil ink surface anti-adhesive material (silicone oil, dusting) can be the first to remove the surface of the anti-stick material and then UV oil or the first base and then UV oil coated roller pattern Too thin to replace the surface of the coating roller For example, if the solvent is excessively thinned, the roller pitch is too small, etc., reduce the proportion of solvent, adjust the gap between the coating roller and the pressure roller. Bottom oil drying is too thorough. Adjust the primer process or replace the new oil machine too fast. The surface of the speed paper is too rough to make the bottom before the UV oil, or change to a smoother surface. The hardness of the base oil is too low. The UV oil penetrates into the base oil and is microscopically diluted, affecting the UV quality of the curing base oil. , Or UV oil wear resistance poor replacement quality is more stable, more wear-resistant varnish UV lamp aging, curing equipment is not completely repaired or replacement UV lamp UV coating with white spots and pinhole coating is too thin to increase the coating Layer thickness, can also be added a small amount of leveling agent or wetting agent Non-reactive diluent (such as ethanol) Add too much Adjust the concentration of UV oil, or dilute the reactive diluent used in the reaction Printed surface More dust control Print Control the amount of dusting, the production environment and the printed surface should be kept clean The surface is coated with stripes and orange peel phenomenon UV Varnish viscosity is too high should be properly reduced UV Varnish viscosity Coat roller texture is too rough Matte roll should be fine Polish, or switch to offset/rubber Inconsistent indirect coating pressure to ensure uniform pressure to ensure that the uniform coating amount is too large to reduce the amount of coating UV Varnish poor leveling can be added a small amount of leveling agent tape test when the UV oil film easy to pull off the ink contains too much flow Flat agent, defoamer dispersant and other difficult-to-stick additives should be printed to avoid excessive addition of these additives. Ink crystallization. Add 5% lactic acid in the UV oil, damage the adhesion of crystallized film base oil to the ink. Inadequate adhesion to the base oil UV oil adhesion is not good, the surface is not smooth enough to change the adhesion, better smoothness of the UV oil, or the first base and then the UV oil curing is not completely slow down properly Speed, maintenance UV lamp base oil is too thin (too much thinning, too small roller pitch, etc.), adjust the solvent ratio, adjust the roller base oil drying too fast and slow down the base oil drying speed is too rough, no ink seal , The bottom oil all went to the paper to adjust the bottoming process, to increase the thickness of the bottom oil, or to use paper with better flatness and smoothness. The paper had poor absorption. When the ink was not dry, it passed UV. After the ink was dried, it passed UV light. Oil, or change to paper UV light that absorbs better Thickening, gelation phenomenon UV light oil storage time is too long Note the effective use of UV light oil Varnish is not completely protected from light Storage is strictly avoid light Storage temperature is high Storage temperature to 5-25 °C is suitable for residual odor Dry curing does not completely slow down the speed, or maintenance of UV lamp UV Varnish Oxygen interference is poor Replacement of UV Varnish UV Varnish Non-Reactive Diluent Add too much Add to the original barreled UV oil Increase the concentration of surface pits phenomenon

Ink has crystallized

Add 5% lactic acid to the UV oil, destroy the crystallized film or perform de-oiling treatment. The surface tension value is large, the wetting effect on the ink layer is not good to reduce the surface tension value, and the surfactant or the solvent tension or wrinkling phenomenon with a low surface tension value is added.

UV oil is too thick, coating amount is too large, mainly in the roll coating to reduce the viscosity of the UV oil, add the appropriate amount of alcohol solvent dilution, or use offset / blanket polishing coating layer poor toughness UV Varnish Improper selection of self-resin and reactive monomer. Replace with new UV varnish. Polished coating is too thick. Add a small amount of thinner. Use a roller with a large number of meshes. Curing process is not properly controlled. Properly slow down the speed or repair and replace the lamp. After glazing, easy discoloration of the base oil leads to acidity and alkalinity of the discolored base oil. The cure should not be high. The thinner in the UV oil penetrates into the ink and dilute, giving a sense of loss of light. Completely cured

Glazing process detection method

Appearance inspection surface has no effect on the appearance of pits, streaks, film cracks, wrinkles, breakage and other defects. Gloss should be consistent with the pattern or customer requirements. Dry thoroughly, no sticky feeling after oil, no adhesion between Zhang and Zhang. Performance test tape test, there should be a good adsorption between the varnish and the substrate. Scratches on the surface of the prints with the nails, the oil film and the substrate should not scratch off. Folding prints, inspection fold line, oil film can not break. If the customer has wear requirements, it should be tested for wear resistance.

Lamination process The lamination process is a process in which a transparent plastic film is adhered to the surface of a printed product by hot pressing to protect and obtain a glossy effect. The coating process is divided into pre-coating and instant coating. The precoating process requires the use of a precoating film, which only requires unwinding, compounding, winding, and mechanical transmission. That is, the coating needs to be glued on the film, and then it is heat-pressed and adhered to the surface of the printed product. Compared with pre-coating, coating and drying are two more processes