The main factors affecting the quality of printed products

Quality is the life. 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 main factors affecting the quality of the printed product.

First, the impact of plate-making film on printing 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 the plate-making 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 plate-making film, and the quality of the printing plate produced with it can be guaranteed. In addition, the thickness of plate-making film base also has an impact on plate-making quality. Generally, thin-film film is better than thick-film film.

Second, the impact of printing on print quality
During the printing process, the intensity of the light source, the distance of the light source from the plate material, and the length of the exposure time all affect the quality of the printing 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 in the visible part of the plate is intensified until the photo-defective film surface is completely decomposed. If the exposure time continues to increase, no light is seen on the edge of the pellicle film surface due to exposure to strong light, and the photographic film gradually begins to decompose, so that the resulting printed image line will become thin, even missing and blurred. If the exposure time is not enough, the non-graphic part will not be completely resolved on the surface of the photochemical film, and the non-graphic part of the printing plate will still have a film, and it will become dirty on the printing. In addition, the exposure time required for different brands of plates is not the same and must be noticed.

In addition, when the printing plate is evacuated, the degree of close contact between the film and the printing plate also affects the quality of the printing plate. If the printing is not carried out, the printed plate may suffer from ghosting and blurring.

Third, the development of the print quality
1. Developer concentration
The concentration of developer is too large and the development is too fast, which can easily cause excessive development of the printing plate. The lines of the images and lines are thin, the fine dots are missing or the images are thin and unclear, affecting the printing quality; the concentration of the developer is too small, and the concentration of the developer is too small. Difficult to clean, easy to dirty when printing on the machine.

2. Development time
If the development time is too long, the film surface where the printing plate is not exposed to light will be easily dissolved, and the printing plate image will become light and thin, resulting in false printing and unclear printing; the development time is too short, and the photolysis film is too short. It is not easy to completely remove the surface and it is easy to get dirty when printing. The proper development time is when the plate is washed after development, and the photolytic film surface just flushes out. 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%. After the printing plate is in contact with the blanket, the ink transfer rate is about 50%; the blanket is then in contact with the paper, and the ink transfer rate is about 76%. It is very important to control the transfer rate of the ink. Ink suitability, ink balance, printing plate, blanket performance, and paper, printers, etc. will affect the ink transfer.

1. Effect of ink properties on ink transfer
Low viscosity. The more mobile inks are easier to transfer, the transfer rate is higher, and the inks with high viscosity and low fluidity have low transfer rates. To increase the ink transfer rate, the viscosity and fluidity of the ink must be controlled. The ink's performance will also vary slightly with the environment. When the temperature is high, the viscosity of the ink is relatively low; when the temperature is low, the viscosity of the ink is higher. In actual production, inks of different types, types, and different drying methods should be selected according to actual conditions. In addition, adding a suitable amount of ink in the ink, you can adjust the ink performance, is conducive to control the dot increase to 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. Influence of the adaptability of paper and printing plate on printing quality
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.

The quality of the base plate of the printing plate, the hydrophilicity of the metal plate, and the oleophilicity of the surface of the coated polymer resin are related to the suitability of the printing plate, affecting the ink transfer and the ink balance of the plate. In the plate-making process, exposure and development will also affect the performance of the plate.

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 the equipment, both the graphic part and the non-graphic part of the printing plate are inked and watered, and they infiltrate each other. Therefore, ink emulsification will inevitably occur on the printing plate. If water and ink are not well controlled, it will inevitably deepen the emulsification of the ink, resulting in stencils and dirty plates in printing. 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, the ink emulsification will vary with changes in the environment, conditions, in actual production, should be based on the actual situation, should grasp the ink viscosity and the pH of the fountain solution to control the amount of ink and the amount of water, to the printing plate does not paste Edition, not dirty version prevail.

5. The influence of printing pressure on printing quality
Printing pressure refers to the interaction between the plate cylinder and the blanket cylinder, the blanket cylinder and the impression cylinder, and it is a necessary condition for ink transfer. The printing pressure is too small, the ink is not easy to convey, the ink is light and weak; the printing pressure is too large; the ink volume expands to the non-graphical part, making the dot gain serious and the image distorted. It is also easy to make the printing plate and the blanket resistant to the printing force. decline. 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.