Glazing method and advantages and defects of glazing machine
At present, there are two kinds of UV glazing method.
(1) Three roller type (ink roller, coating roller, pressure roller). The advantage of this method is fast and adjustable; The defect is that it is not suitable to polish on tissue paper. Although some glazing machines have wind knives, but the glazing effect on thin paper is not safe, the oil layer is thick. Therefore, this method is suitable for board paper.
(2) tooth type (imprint roller with teeth). The advantage of this method is that thin and thick paper are suitable for oil saving, oil layer thickness is easy to adjust, because the diameter of the imprint drum is large, the pressure is large; The defect is that the speed is not easy to adjust.
When using UV glazing oil in packaging and printing, because of the influence of skills, data, equipment, environment and other factors, there are often some problems. When summed up, there are the following questions.
(1) UV varnish and ink incompatibility, stripes and orange peel appearance.
Specific performance is UV oil coated on some ink bead, curing like orange peel, or although can be coated evenly without foaming, but if the sharp tool scraping, UV oil layer will be separated from the ink layer. The primary reason is that the UV varnish viscosity is too high; The rubber roller line is too thick (the amount of coating is too large), the appearance is not smooth; Coating pressure is not uniform; The leveling of UV varnish is poor. The solution is to first play a layer of bottom oil, and then coated UV oil, or after the disposal of electric spark UV oil, appropriate mixed with alcohol infrared oil.
(2) UV varnish adhesion is not good, oil can not be coated or flower. The primary reason is that the UV varnish viscosity is too small, the coating is too thin; Ink adjusting oil or dry oil content is too high; Printing ink surface crystallization; Printing ink additives are not suitable; The appearance of ink anti adhesion data (silicone oil, powder) too much; Gelatinized roller line is too thin; Light curing conditions are not suitable. The solution is to reduce the UV varnish viscosity, reduce the amount of coating; Adjust the pressure evenly; The coating roll should be ground fine and polished; Participate in the gloss leveling agent. When printing should adopt the corresponding measures according to the glazing conditions; UV varnish can be thickened appropriately; When necessary, the bottom oil or select a special light oil; An adhesive base oil is applied to the printed goods.
(3) UV gloss and brightness after the ambition. The first reason is the lack of oil supply; Paper surface brightness is not good or rough appearance is not fine, absorption is too strong; UV varnish viscosity is too small, the coating is too thin; Excessive dilution of non-reactive solvents such as ethanol; UV oil coating is not uniform. The solution is to apply the base oil first. In addition, UV oil expiration or UV oil quality doubt will also make after glazing is not bright. According to the different appropriate progress of UV varnish viscosity and coating amount of paper, the paper with strong penetration absorption can be coated with a layer of bottom oil or replace the paper with good smoothness.
(4) UV oil layer is brittle, when the fold crease brittle crack. Can use polyurethane oil, fold when the first indentation, tissue paper fold with hand do not use bamboo fold. UV oil layer is too thick will also present this problem, can adjust the amount of oil.
(5) Alcohol UV oil is easily dissolved by ethanol after curing. Such as wine box on UV oil, in the process of transport if there is a bottle break, wine will be UV oil dissolved. The solution is to use UV oil that is insoluble in alcohol.
(6) boring is not good, curing is not complete, the appearance of sticky. The first reason is that the UV intensity is not good; Ultraviolet tube aging, strength weakening; UV varnish storage time is too long; Do not participate in the reaction of diluent participate too much; The machine is too fast. Solution: when the curing speed is less than 0.5s, the power of the high-pressure mercury lamp should be ensured not less than 120W/cm; Lamp to timely update: when necessary to participate in a certain amount of UV light oil curing promoter, speed up boring.
(7) UV oil coating too thick is not economic and will form brittle crack. The solution is to heat the UV oil to 50-55℃ or add diluent in the UV oil.
(8) UV oil after curing active burst. The reason is that UV light is excessive, the external temperature of the subject is too high. Solution IS TO INCREASE LAMP TUBE AND BE ILLUMINATED OBJECT EXTERIOR INTERVAL, MAKE BE ILLUMINATED OBJECT IS FAR FROM LAMPSHADE FOCAL POINT, AFTER CURABLE AGILE COOLING, USABLE COOL AIR OR COLD ROLL PRESS OR WITH AIR COOL, WATER COOL ILLUMINANT.
(9) on the occurrence of oil spot. The primary reason is that the amount of oil thickness is not good, the pressure light temperature is not good, the pressure plate is not suitable, the quality of paper is not consistent. Appropriate information should be adjusted or replaced for the specific situation.
(10) the glazing coating has white spots and pinholes. The first reason is that the coating is too thin; Rubber roller is too fine; Excessive participation of non-reactive diluents (e.g., ethanol); Print appearance more dust. Should adhere to the production environment and printing appearance cleaning; Increase the coating thickness; To participate in a small number of lubricating additives: diluent best to participate in the response of the active diluent.
(11) Large residual odor. The primary reason is that UV varnish curing is not complete; Lack of ultraviolet light or aging lamp tube; Poor antioxidant ability of UV varnish; UV varnish non-reactive diluent to participate in too much. UV varnish should be completely cured, strengthen ventilation, and replace the type of UV varnish when necessary.
