Analysis of the Influencing Factors of Product Luminosity

Gloss can increase the surface gloss of printed products, and at the same time enhance the wear resistance, moisture resistance and water resistance of the products, thereby improving the product performance. However, there are many factors that affect the quality of glazing. It is of great significance to correctly understand the conditions that affect the brightness of glazing and to adopt corresponding technological measures to solve them. This is of great significance to avoid operational blindness and improve production efficiency and product quality. The following analyzes the factors affecting the quality of glazing and proposes corresponding solutions.

1 paper coating quality

The quality of paper coating directly affects the brightness of the product after coating. We know that good quality coated paper has strong surface gloss and weak oil absorption. After coating, a large part of the oil floats on the surface of the paper, and it is easy to form an oily film with a certain brightness. Conversely, if the quality of the paper coating is poor or no coating is performed, due to the strong oil absorption on the paper surface, a considerable part of the oil penetrates into the fibrous structure of the paper after the coating oil is applied, resulting in a lack of brightness after coating. . Therefore, we must choose paper and use good paper for products that need to be glazed. If the paper quality is bad, the oil absorption is strong, and it is a semi-finished product that has already been printed, only by taking the following measures to make up for: the use of high-bright paint; appropriate increase in the proportion of the use of coating oil; appropriate increase in the coating of oil Coating thickness; appropriately reduce the speed of glazing so that the contact time between the paper surface and the applicator roll is properly lengthened; secondary glazing is performed.

2 Varnishing process

Polishing oil as the main material of the glazing process largely determines the effect of glazing on the product. Improper mastering of the glazing oil is also one of the major causes of glazing insufficiency. Practice has shown that the optimal concentration and dosage of coating oil are closely related to the size of oil absorption on the paper surface, the temperature of the production environment, and the speed of the machine. When the oil absorption of the printed paper surface is large, the concentration and amount of the coating oil should be increased accordingly, so that a certain thickness of the light film layer can be formed on the paper surface. If the temperature is high, the varnish becomes thin. When the varnish is blended, it is necessary to appropriately reduce the amount of thinner, so as to increase the concentration of the varnish to increase the brightness of the product. Conversely, if the temperature is low, The concentration of varnish appears to be high, and the amount of diluent must be appropriately increased during the formulation. The speed of the machine when glazing is fast, and the friction coefficient of the rollers of the glazing machine is relatively large. When the glazing oil is heated, it will become dilute. The concentration and the output of the glazing oil have to be adjusted accordingly. In addition, there are many types of varnish, and their characteristics are more or less different to some extent. Therefore, the proportion of coating varnish under various conditions is difficult to quantify with specific values. So, how to explore and master the best process ratio of Varnish in production? The author believes that the most important thing is to sum up the good production experience. Only in this way can we avoid blindness in the process. This requires us to make a careful record of the use of each coating and thinner. The records include the on-site temperature at the time of production, the speed of the machine, the paper quality, and the proportion of coating oil and thinner. , and the glossiness effect of the product after polishing, etc., in order to analyze and summarize the experience, so that the proportion of the dispersion of different manufacturers or different varieties of coating oil and thinner under various production conditions is more in line with the actual production situation, in order to obtain The best glazing effect.

3 operating process and equipment factors

1) The brightness of the coating caused by the speed of the machine is not enough. The speed of the coating machine also has a certain relationship with the brightness of the products. If the speed of the machine is fast, the contact time between the paper surface and the coating roller is short, the oil absorption of the paper surface is also small, and the brightness of the coating is relatively low. Worse. Therefore, when polishing paper with strong paper-absorbing properties, the speed of the machine should be relatively slow to increase the brightness of the product.

2) Whether the gap between the coating roller of the coating machine and the backing roller and the metering roller is appropriate also directly affects the brightness of the product. If the clearance between the coating roller and the backing roller is adjusted too much, it is easy to make the paper surface of the coating contact with the coating roller poor, so that the oil absorption on the paper surface is reduced accordingly. If the gap between the coating roller and the metering roller is too small, the coating amount of the varnish is determined. Therefore, the gap between the applicator roller and the metering roller should be adjusted according to the strength of the paper surface to ensure the gap size. The brightness of the product.

3) Insufficient glazing brightness due to poor equipment. When the roller body on the machine is worn, bent or eccentric, and the shaft head and sleeve of the roller appear beating due to wear and looseness, the gap between the coating roller and the lining roller and the metering roller will also be unstable. , resulting in uneven coating on the coating, the lack of brightness on the surface of the product. In this regard, careful observation and analysis should be adopted to take appropriate measures to eliminate the malfunction. If the rubber roller body is worn or deformed, the car wheel can be machined. If it is not possible to remove the rubber, the roller should be cast again. For the bending deformation of the roller body, correction and correction should be carried out. If the shaft head and the sleeve are worn out, they can be repaired by mechanical processing to eliminate the abnormal coating of the coating caused by looseness of the roller shaft.

Source: "Printing World"

Author: Kang Kai