Fault analysis and treatment of the most popular p

Fault analysis and treatment of glazing processing

first, there are streaks or wrinkles on the film surface

the possible reasons are: the viscosity value of glazing paint is high, and the paint is too late to level, so streaks are easy to appear. According to the different suitability of the printed matter, the glazing paint with good leveling and wettability can be selected; Or add an appropriate amount of diluent to reduce the viscosity of the coating. If the coating amount is too large, the coating amount can be reduced by adjustment; Sometimes, the glazing coating has poor wettability to the ink layer on the surface of the print, which affects the smoothness of the drying film, or the leveling property of the coating is poor, and the process conditions do not match the suitability of the coating. Other types of glazing coatings may be used or the process conditions may be changed to match the performance of the coating

second, the printed matter adheres to each other

the reason is: the solvent in the glazing paint is volatile, and the drying performance of the paint is poor. We can consider changing the solvent with high evaporation rate or changing the type of glazing paint; It may also be that the coating film is too thick, the solvent inside the coating is not completely volatilized, and the residue is high, reducing the thickness of the film layer; Or the working temperature is low in glazing coating or calendering, and the drying time is short, which makes the coating dry poorly. It can improve the working temperature in glazing coating and calendering, reduce the machine speed, and make the coating dry completely

III. poor gloss of film-forming film

if it is the quality problem of coating, it should be considered to use a high-quality coating according to the process and economic requirements; If the coating is too thin, the coating amount is insufficient or the coating concentration is small, and it is not easy to fill up the surface of the printed matter with high roughness and strong absorption, the coating amount should be increased, and the coating plastic recycling granulator should process the waste plastics in daily life to generate the plastic raw material concentration required by the enterprise again, or apply a layer of gloss primer before processing, and then polish and coating; It may also be that the temperature during glazing, coating, drying and calendering is low, and the calendering pressure is small, then the process parameters should be adjusted during operation to increase the temperature and pressure; It is also estimated that the reason is the equipment itself. If the calendered steel strip is worn and the gloss smoothness decreases, it is necessary to repair and improve the surface condition of the calendered steel strip

IV. after calendering, the blank part of the print is light colored, and the light colored part changes color

the reason may be: the glazing coating solvent has a certain dissolution effect on the ink layer, which requires changing the coating type or changing the solvent composition; If the ink dries poorly and the solvent resistance of the ink layer is not good, it is necessary to improve the ink drying condition, and then polish and coat after the ink dries, so as to reduce the amount of solvent that dissolves the ink in the glazing materials; If the coating layer is not completely dried and the solvent residue in the film layer is high, it is necessary to increase the drying temperature or reduce the machine speed during glazing and coating, extend the drying time and reduce the solvent residue in the coating

v. uneven coating, bubbles, pockmarks, etc.

the reason is: the surface tension value of glazing coating is large, and the wetting effect on the ink layer on the surface of printed matter is not good. We should reduce its surface tension value and improve the wetting effect of coating on the ink layer according to different samples and experimental forces; The solvent in the coating volatilizes poorly, and the solvent residue in the coating is high. You can use the solvent with high volatilization rate or press polish after thoroughly drying the coating; It may also be that the machine speed in glazing and coating is too fast and the drying temperature is low, which makes the coating drying incomplete and the solvent volatilization incomplete, so the process conditions of glazing and coating should be adjusted; The ink layer on the surface of printed matter will also produce crystallization, which requires effective measures, such as removing the oil on the crystallization surface of the ink layer or roughening, improving the wetting effect of the coating on the ink layer, so as to weaken or eliminate the adverse effect of the crystallization of the ink layer on the glazing coating

VI. blistering on the film surface

the reason is: during the calendering process, the pressure is too high, and the temperature of the calendering steel strip is too high, which makes the coating film locally soften, which requires appropriately reducing the calendering pressure and temperature; It may also be that the glazing coating is matched with the calendering process conditions. After the coating layer on the surface of the print is cooled, the stripping force of the same light band is poor. It is necessary to change the process conditions to match the glazing coating, reduce the calender speed, and improve the stripping force between the coating layer and the same light band

VII. In calendering, the process of poor adhesion between printed matter and glazing tape is very troublesome, and this is the process of users. They also have to pay a certain amount of money to start and eliminate

the reason is: the coating is too thin, and the coating amount should be increased; If the viscosity of the coating is too low, increase the viscosity of the coating; Then, the pressure of calendering is too small and the calendering temperature is insufficient. It is necessary to increase the calendering temperature and pressure in order to avoid accidental injury or death

VIII. After calendering, the surface of printed matter is easy to crack

the reason is that the high temperature makes the printed matter dehydrated too much in calendering, and the water content is reduced, so the paper fiber becomes brittle. The working temperature in calendering should be reduced, and effective measures should be taken to maintain a certain water content in the printed matter; Excessive pressure in calendering reduces the extensibility and plasticity of printed matter, and the toughness becomes worse, which can reduce the pressure in calendering; If the post-processing adaptability of glazing paint is poor, the glazing paint with good post-processing adaptability should be re selected; If the post-processing process conditions are not suitable, the post-processing process conditions can be adjusted to match the suitability of the printed matter after calendering

IX. the brightness of the film surface on both sides is inconsistent after calendering

the reason is: during calendering, the pressure on both sides of the calendering belt is not equal, or the wear on both sides of the calendering belt is not consistent, the pressure on both sides of the calendering Belt should be adjusted to make it equal, and the parallelism of the hot pressing roller and the transmission roller should be adjusted to make the tension on both sides of the calendering belt consistent and wear evenly; It may also be that the thickness of the glazing coating is uneven on both sides, so it is necessary to adjust the glazing coating mechanism, check the parallelism and gap between the metering roller and the coating roller, and make the coating thickness on both sides as consistent as possible

reprinted from: Printed today