The relationship between the characteristics of th

2022-08-03
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The relationship between paper characteristics and printing glazing quality "> the supporting production process of printing, such as trademark labels, product advertisements, invitations, book covers and other printed materials, can increase the gloss and artistic effect of the printed surface, beautify the function and function of the printed materials, make the surface color of the products more colorful, give people a beautiful visual effect, and double the value of the products. Polishing is also an important method to improve the appearance effect, use performance and protection performance of the printed materials, and also to improve the An effective way to improve the quality and grade of printed matter. It is of great significance for improving the quality of color printing products to correctly understand some situations related to the glazing quality of printing products and then take corresponding technological measures for effective control

I. The relationship between paper characteristics and the polishing quality of printed products

the process practice shows that the polishing quality of printed products is directly related to the performance of the paper. The paper with good surface smoothness has weak absorption. After the polishing oil (paint) is coated, the oil layer will float on the surface to form a high brightness film. The paper with poor smoothness, due to its rough surface, will be quickly absorbed by coarse fibers after the polishing coating is applied to the paper surface, so the paper surface will not form a bright coating, and the gloss effect will be poor. Therefore, the higher the smoothness of the paper, the better its glazing effect. In the actual production process, if the smoothness of the paper surface is poor, in order to improve the polishing effect of the print, a layer of casein primer can be coated on the paper surface before polishing to play the role of backing, so that the polished oil layer floats on the paper surface after polishing the print to form a high brightness film. It can be seen that the absorption of the paper surface affects the leveling of the glazing coating from the beginning of coating to drying. This is precisely because the paper surface absorbs the solvent in the glazing coating, which increases the viscosity of the glazing coating over a period of time, and the internal resistance of the coating layer flowing on the paper surface increases, so its leveling is poor, that is, if the glazing oil is not smooth during coating, it cannot form a continuous and uniform film, resulting in poor paper gloss, This is the inevitable performance of paper absorption. Therefore, in the actual production process, the glazing process and glazing coating should be adjusted according to the actual production conditions and the paper's absorption and smoothness. If the paper absorption of the printed matter is too strong, the viscosity of the glazing coating should be appropriately increased, that is, the amount of diluent should be appropriately reduced. Process practice shows that the quality and characteristics of paper and paperboard directly affect the quality of glazing products to a great extent. For example, due to the smooth surface of coated paper, the gloss effect will be significantly improved after polishing. However, the surface gloss of white board paper or white card paper is relatively poor, and the brightness of printed matter after polishing is not significant enough. This is because the polishing oil is easily absorbed by the cardboard fiber and does not float on the paper. In order to make up for the lack of brightness due to the easy oil absorption of paper, the proportion of paint can be appropriately increased, and the method of two passes of varnish can be adopted to increase the brightness of printing

II. The relationship between printing ink and the glazing quality of printed matter

the characteristics of printing ink are also an important factor affecting the glazing quality. The affinity of printing ink layer and the particle size of printing ink will directly affect the coating quality and leveling of glazing oil. If the ink layer on the print cannot be compatible with the glazing coating, it is difficult for the glazing oil to form a smooth and uniform film on the paper. If the printing ink particles are large and the pigment dispersion is small, the leveling property of the varnish on the paper is poor, which makes it difficult to form a high-quality continuous film. When the printing ink layer is not dry well, the polishing coating is also difficult to obtain good gloss effect, and even prone to chain quality problems such as sand holes and bubbles. In addition, the printing ink must have solvent resistance and heat resistance, otherwise the printed text will change color or produce wrinkled skin and other undesirable phenomena. Therefore, the printing ink for glazing products should be alcohol and ester solvent resistant and acid and alkali resistant. At the same time, it should have the characteristics of long-lasting non discoloration and good gloss, and have a strong printing effect on the paper. In order to prevent the variation of printing ink color after glazing and affect the quality of products

III. relationship between production temperature and printing glazing quality

the production process shows that temperature also has a certain relationship with glazing quality. Because, The temperature will affect the concentration of Polish "The last packaging box used up by the consumer can be kept in the post station for consistency and fluidity. Usually, the printing polishing temperature should be controlled at about 20 ℃, which can achieve relatively good results. However, in winter when the temperature is low, the polishing oil is easy to solidify and thicken due to the low temperature, and the fluidity of the polishing oil is poor. The oil film on the surface of the printed product after polishing is easy to be uneven, and the mechanical parts will fail. The quality of the printing coating is also poor That's bad. In order to overcome the problems caused by environmental change factors, the glazing oil should preferably be placed indoors with relatively stable temperature. Generally, the glazing oil shall be placed in the room at room temperature ℃ to maintain a relatively stable fluidity

IV. The relationship between the characteristics of glazing coating and the glazing quality of printing products

the viscosity of glazing coating has a great impact on the leveling and wettability of the coating. When the surface gloss and absorption of printing products are different, the viscosity of the coating used should also be different, so as to achieve better results. This requires that when determining the viscosity of glazing paint, it should be fully considered according to the characteristics of the material, so as to better ensure the quality of glazing. As the paper and paperboard with the same absorption performance have an inverse ratio to the viscosity of the coating, that is, the smaller the viscosity of the coating, the stronger the absorption. Therefore, high gloss paper, paperboard, varnish viscosity can be appropriately low. The surface tension of the glazing coating is also an important factor affecting the coating quality. The glazing coating with small surface tension can easily and better wet and adhere to the surface of the printed product, that is, the surface tension reduces the surface area of the glazing coating, making it smooth and uniform continuous coating. However, the glazing coating with large surface tension has certain limitations on the wetting of the print surface. When the surface of the glazing coating is a typical innovative product that can use the Internet, and the tension value is greater than the surface tension value of the ink layer on the print surface, the coated glazing coating is prone to a certain shrinkage, or even sand holes. In addition, the evaporation rate of solvent in glazing coating also has a great impact on the quality of glazing coating. When the solvent volatilizes too fast, the viscosity of the glazing coating will change too much within a certain period of time, and its leveling property will also change suddenly, making it difficult for the coating to achieve leveling in time and unable to form a continuous and uniform coating layer, which is easy to produce streaks and sand holes, and may also induce moisture condensation, resulting in cracking and whitening of the dried coating

v. the relationship between the crystallization of the printing ink layer and the polishing quality of the printing product

when the coating area of the printing bottom color ink is large, the printing semi-finished products are placed for a long time, and because excessive dry oil is added to the bottom color ink, the printing ink layer forms a crystallization phenomenon on the paper surface. In this way, the coating is not easy to adhere to the ink layer during polishing, which is easy to cause the oil layer to be scratched and uneven. If this is the case, as long as you add 5% lactic acid to the 70mm glazing oil, stir it evenly and then apply it. By using the modified glazing oil, the glass crystalline film on the surface of the printed product can be damaged, so as to achieve the requirement of evenly adsorbing the glazing oil and form a bright film on the ink layer

VI. the relationship between the machine and the polishing quality of printed products

the precision and operation process of the polishing machine are also closely related to the polishing quality of printed products. When the coating roll, coating amount control roll and pressure roll of the machine have bending deformation and poor roundness, and there is a wear gap at the roller head or bearing bush, it will cause instability and uneven polishing coating. In addition, if the gloss of the paper is poor and the absorption is high, and the polishing speed of the machine is too fast, it is easy to cause insufficient brightness of the printing. In order to ensure the polishing quality of printing products, attention should be paid to the lubrication and maintenance of the machine at ordinary times to reduce the wear and looseness of the roller shaft. If the associated parts of the machine coating device have been worn, deformed and other undesirable phenomena, measures shall be taken to repair and correct them in time. In addition, in the process of glazing, attention should be paid to reasonably controlling the glazing speed according to the characteristics of the printed surface to ensure the quality of glazing coating

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