Talking about the Factors Affecting the Quality of Offset Printing

Content: Quality is the life of a business. The quality of the product is directly related to the market competitiveness of the company. In the printing production process to ensure the quality of printed matter, eliminate the quality problems caused by technical errors, it is necessary to pay attention to the work. This article analyzes the printing process and discusses the following factors that affect the quality of the printed product.

First, the impact of film on print quality

The process of developing and fixing the film after exposure directly relates to the sharpness and contrast of the image on the film. Therefore, for making-version-film, the key is to look at the density of the graphic part and the contrast between the graphic part and the non-graphic part. The higher the density, the greater the contrast and the better the quality of the system-plate-film, and the quality of the printed-printed plate produced by it can be guaranteed. In addition, the thickness of the system-printing-film base also has an impact on the quality of the system-plate-making. In general, the thin film is better than the thick film.

Second, the sun - version - the impact of print quality

During the sun-printing process, the intensity of the light source, the distance from the source to the plate, and the length of the exposure time all affect the quality of the sun-plate. Strong light source, short distance, relatively short exposure time; weak light source, long distance, relatively long exposure time. Under a certain light source and distance, as the exposure time increases, the decomposition of the film of the plate-plate-light-seeing part is intensified until the surface of the photopharmaceutical film is completely decomposed. If the exposure time continues to increase, no light is seen on the edge of the film surface due to the radiation of strong light, and the photosensitive film gradually begins to decompose, so that the printed-printed-image lines produced will become thin or even missing. blurry. If the exposure time is not enough, the non-graphic part of the photopharmaceutical film surface is not completely decomposed, and the non-graphic part of the printing-printing-developing film still has a film, and it will become dirty when printed on the machine. In addition, the exposure time required for different brands of print-printing is different and must be noticed.

In addition, the degree of adhesion between the film and the printing plate-printing plate also affects the quality of the tanning-printing plate during the tanning-printing-vacuum printing. If the tiling is not carried out, the printed plate-printed plate may be ghosted and blurred. Such as failure.

Third, the development of the print quality

1. Developer concentration

The developer concentration is too large, the development is too fast, easy to cause India - plate - excessive development, graphic lines become thinner, fine dots or light and thin images are unclear, affect the printing quality; developer concentration is too small, see photolysis of drugs Membrane surface is not easy to clean, easy to print on the machine - version -.

2. Development time

The development time is too long, the printing film surface of the printed-printed-unvisible light is easily dissolved, and the printing-printing plate-graphics will become light and thin, resulting in false printing and unclear printing; the development time is too short, and the light is too short. The decomposed film surface is not easy to remove completely, and it is easy to get dirty when printing. The proper development time is the printing-printing-developing rinse, and the photo-degraded film surface is just flushed. If the concentration of the liquid is relatively large, the development time should be shortened accordingly; otherwise, the development time should be extended accordingly.

Fourth, the impact of ink transfer on print quality

The printing process is actually the process of ink transfer. In general, the overall ink transfer rate of offset printing is low, about 38%. Printing --- version --- after contact with the blanket after the ink, ink transfer rate of about 50%; blanket and then contact with the paper, ink transfer rate of about 76%. It is very important to control the transfer rate of the ink. Ink suitability, ink balance, printing --- --- --- blanket performance and paper, printers, etc. will affect the transfer of ink.

1. Effect of ink properties on ink transfer

The inks with low viscosity and high fluidity are easier to transfer, and the transfer rate is higher; the transfer rate of inks with high viscosity and low fluidity is small. To increase the ink transfer rate, the viscosity and fluidity of the ink must be controlled. The performance of the ink will also vary slightly with the change of the environment, and the viscosity of the ink will be relatively low at high temperatures. When the temperature is low, the viscosity of the ink will be higher. In actual production, inks of different types, types, and different drying methods should be selected according to actual conditions. In addition, the addition of appropriate amount of ink in the ink, you can adjust the ink performance, is conducive to control the dot increase, increase the ink transfer rate.

2. Effect of blanket performance on ink transfer

Blanket must have good ink absorption and ink transfer, but also must have oil, acid, alkali, good elasticity and other characteristics. If the blanket is not completely cleaned after printing, the ink retained in the fluff will gradually harden, causing the villous structure on the surface of the rubber to be damaged, which will directly affect the ink-receiving rate of the blanket and reduce the ink transfer rate of the blanket. For this reason, after the printing is completed, the blanket should be thoroughly washed. If the downtime is relatively long, a layer of pumice powder can be rubbed on the surface to keep the surface of the blanket in a villous structure. Ensure that the blanket has good ink receptivity and ink transfer.

3. The Influence of the Suitability of Paper, Printing and Printing on the Quality of Printing

The suitability of paper is mainly reflected in smoothness, whiteness, stiffness and other aspects. Paper with high smoothness requires a relatively small amount of ink; paper with poor smoothness requires a relatively large amount of ink. In the printing process, different papers vary according to their surface conditions, and the amount of ink required varies accordingly. With the same variety, the same quantity, and the same price, the paper with higher smoothness and whiteness has a better print quality than the paper with lower smoothness and whiteness.

Imprint--Version--Version--The quality of base sand, metal-plate-face-hydrophilicity, and the oleophilicity of coated polymer resin film surface are related to the suitability and influence of imprint-printing-- Ink transfer and - plate - surface ink balance. In the process of making-printing, the quality of exposure and development will also affect the performance of printing-printing.

4. The Influence of the Ink Balance on Printing Quality

The ink-and-wash balance is a relative balance, not an absolute balance. In the process of high-speed operation of equipment, printing and printing --- the image part and the non-graphic part are both inked and watery, and they infiltrate each other. Therefore, the ink emulsification will inevitably occur on the printing plate. phenomenon. If the amount of water and ink is not well controlled, the ink emulsification will inevitably deepen, resulting in the occurrence of paste in the printing --- --- ---, and --- --- version. Printing methods are usually used to reduce the amount of water, the appropriate increase in the amount of ink, but some will reduce the amount of ink. In addition, ink emulsification - with - ring - environment -, conditions change with different changes, in actual production, should be based on the actual situation, should grasp the ink viscosity and run - the version - the pH value of the liquid to control the ink Quantity and amount of water, with printing - version - not paste - version, not dirty - version - prevail.

5. The influence of printing pressure on printing quality

The printing pressure refers to the printing ---printing --- the interaction between the cylinder and the blanket cylinder, the blanket cylinder and the impression cylinder, which is a necessary condition for ink transfer. Printing pressure is too small, ink is not easy to transmit, ink is light and weak; printing pressure is too large, and the amount of ink is extended to non-graphical parts, making the dot gain serious, image distortion, but also easy to print --- version --- And blanket resistance decreased. Therefore, the mechanical pressure must be properly adjusted. Different quantitative papers require different printing pressures, and only proper printing pressure can ensure uniform ink and uniform shades.

Fifth, the impact of the post-press process on product quality

The impact of the post-press process on product quality is mainly reflected in the size of the product specifications, whether the pages are incomplete, and whether the order is reversed. Whether the binding is firm and the appearance is beautiful. The post-printing process is also a process that cannot be ignored in the entire printing process.

There are many factors that affect the quality of printed products. However, from the process point of view, the above-mentioned several major factors are more likely to bring about quality problems. By understanding these factors and controlling them, you can ensure the quality of your prints, reduce the number of unqualified products you can avoid, reduce printing costs, and increase your competitiveness.

Source: China Equipment Network