Matters needing attention in the printing process of coated paper
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Coated paper is an important material for the packaging and decoration printing process. The quality of the printing of the product depends largely on the superiority and inferiority of the material itself and the degree to which the operator has mastered the characteristics of the paper. That is to say, in order to print the coated paper products, the corresponding technical measures must be taken according to the characteristics of the paper. Therefore, it is necessary to understand and understand the technical requirements of printing coated paper.
The classification of coated paper is divided into single-sided light and double-sided light according to the difference of filling and calendering in the process. From the nature of the coating, the casein coating is further divided. Therefore, coated paper is also called coated paper. Due to the defects in the process of some domestic coated papers, it is easy to produce different degrees of powder removal and stretching variation, especially single-sided coated paper is more prone to curling defects, affecting the accuracy of overprinting. Some of the art of printing coated paper is improperly operated, and it is easy to produce sticky (over-bottom), powdering, slow-drying, star-light illuminating, etc., so the following problems should be noted.
1. For each batch of coated paper, before it is put into use, it should deal with the paper's smoothness, pH, absorbency, dryness, stretchability and surface bond strength, etc., and test and analyze it. The characteristics of the paper, the corresponding process measures, such as adjusting the viscosity, fluidity, dryness and anti-sticking measures of the ink, in order to achieve standardized scientific production, to prevent the occurrence of poor printing;
2, to better the pad technology and printing pressure to ensure that the printing ink layer is uniform and bright. The printing pressure of coated paper should be uniform and appropriate. Excessive pressure is easy to produce bad powder, and it is easy to cause unclear defects in the dot blot and increase the wear of the printing plate. On the contrary, it is easy to cause the dot imprinting to be weak, and blindly increase the ink layer to compensate for the embossing caused by insufficient pressure. As a result, it is easy to produce adverse effects such as sticky, slow drying, overprinting, etc., so the printing plate paper pressure should be uniform. , to be appropriate. The liner is made of a neutral hard material.
3, printing trademarks, packaging products with coated paper, often with a light color as the background color, through the overprinting. In this way, the right process is improperly printed, and it is easy to cause some problems and affect the quality. Therefore, when blending the base color ink, heat-resistant and light-resistant inks should be used as much as possible, and the thinner is preferably formulated with a bright paste, so that the ground color can be placed. The final printing effect is better, to prevent the base color from being printed and easily rubbed to damage the ink layer.
4. Since the copper plate is smooth on the surface and the ink absorption capacity is poor, when printing the solid version of the large layout, it should try to achieve "deep ink thin printing". That is, the ink phase is appropriately deepened, so that the ink layer is correspondingly or thinner during printing, that is, it can meet the requirements of printing hue, and can reduce the chance of occurrence of overprinting, and can prevent the color from being printed. In addition, due to the poor adhesion of the paper, the printed ink layer may be easily discolored by falling off the powder. For this reason, the first color of the printing may be made of No. 19 resin oil as the varnish. In order to make the superimposed ink layer bright, some varnish and dry oil may be added to the ink.
5, coated paper due to the large amount of paint, the printing process often encounters the phenomenon of powder removal and the print surface of the printed product. In this case, you should pay attention to check whether the loading process operation, such as the printing plate is not biased, because the paper surface pressure is too large, it is easy to crush the coating powder on the surface of the coated paper, resulting in powder removal and Black shadow spots. In addition, it should also check whether the ink viscosity is suitable. If the printing ink layer is too thick and too sticky, it is also one of the reasons for the paper surface falling off and stacking the layout. In this case, the auxiliary material should be considered to adjust the ink. Quality, the above quality problems can be better overcome.
6. It is necessary to turn off the anti-sticking technology of the coated paper. Coated paper has weak ink absorption and smooth back surface. Therefore, printing with large amount of ink or multi-color overprinting is prone to sticky problems, so it should be overcome by anti-sticking measures, such as taking appropriate amount of light oil. The anti-adhesive agent is evenly mixed, and the liquid is added to the ink and then stirred evenly, and a good anti-sticking effect can be obtained when printing. However, the amount of anti-adhesive agent should be properly controlled, and should not exceed 4%, so as to avoid the occurrence of defects such as ink emulsification, printing ink layer fading and ink layer gloss.
In short, as long as the printing of copper paper is in control of its characteristics, and the correct printing and operation technology, it can not only improve the printing efficiency, but also effectively ensure the printing quality.