Product quality is the life of a company. The quality of a 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. The following will be analyzed from the printing process to discuss the main factors affecting the quality of printed products.
First, the impact of plate-making film on printing quality
The development and fixing process of film (film film) after exposure is directly related to the sharpness and contrast of the film image on the film. Therefore, the key to making the film (film) depends on the density of the graphic part, and the graphic part and the non-image. The contrast of the text part, the higher the density is, the greater the contrast is, and the better the quality of the plate-making film is, the quality of the plate produced by it can be guaranteed. In addition, the thickness of the plate-making film also affects the plate-making quality. In general, the thin film (film film) is better than the thick film.
Second, the impact of printing on print quality
During the printing process, the intensity of the light source and the distance between the light source and the exposure time will 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 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 side because of the strong radiation, the photo-resist film begins to gradually decompose, so that the resulting plate graphic lines will become thin or even missing, blurred. If the exposure time is not enough, the non-graphic part of the photopharmaceutical film surface is not completely decomposed, and after the plate is developed, the non-graphics and the drug film will be dirty. 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 vacuumized, the degree of adhesion between the film and the plate also affects the printing quality. If the printing plate is affixed to the plate, it may cause problems such as ghosting, inaccurate printing, and unclear printing.
Third, the development of the print quality.
A: developer concentration
The concentration of developer is too large and the wet image is too fast, which may cause excessive development of the printing plate graphic. The thin lines of the graphic lines are thin and the dots are missing or the graphic is unclear. The printing quality is affected, the developer concentration is too small, and the light is decomposed. Membrane surface is not easy to clean, easy to dirty version when printing.
B: Development time
If the development time is too long, the surface of the film where the plate is not visible will be easily dissolved, the plate image will be lightened, and the thinning will cause the printing product to be unrealistic; when the development time is too short, the photo-degradation film surface will be too short. It is not easy to remove completely 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, whereas the development time should be extended.
Fourth, the impact of ink transfer on print quality
In fact, the printing process is the process of ink transfer. In general, the total ink transfer rate of tinplate printing is low, about 38%. After the printing plate is inked, the ink transfer rate is about 50%. The blanket is then in contact with the tinplate. Film contact, ink transfer rate of about 76%, control of ink transfer rate is very important, ink fitness, ink balance printing blanket performance tinplate, printing presses will affect the ink transfer.
1. Effect of ink performance on ink transfer
The ink with low viscosity and high fluidity is easy to transfer, the transfer rate is high in viscosity, and the ink with low flowability has a low transfer rate. To increase the ink transfer rate, the viscosity of the ink must be controlled so that each fluidity is good. The performance of the ink will change with the environment. The length of time the printer runs will change slightly. When the temperature is high, the viscosity of the ink is relatively low. When the temperature is low, the viscosity of the ink is relatively high. In actual production, different models should be selected according to the actual situation. The type and ink of different drying methods. In addition, adding appropriate amount of ink in the ink can adjust the ink performance, which is beneficial to control the dot gain, or reduce the ink transfer rate.
2. The effect of blanket performance on ink transfer.
The blanket must have good ink absorption and ink transfer properties, and it must also have characteristics such as oil resistance, acid resistance and alkali resistance. If the blanket is not thoroughly cleaned after printing, the ink retained in the pile will gradually harden, causing the villous structure on the surface of the blanket to be damaged, directly affecting the ink-receiving rate of the blanket, and decreasing the ink transfer rate of the blanket. During printing, the blanket must be cleaned regularly to maintain the elasticity of the blanket. After the printing is completed, the blanket should be thoroughly washed. If the downtime is long, wipe the surface with a rubber reductant or wipe with water. The cleaning is performed so that the surface of the blanket always maintains the original velvet-like structure, and the blanket is guaranteed to have good ink-receiving and ink-transmitting properties.
3, the influence of the suitability of tin plate on printing quality
The adaptability of tinplate is mainly reflected in the degree of tension, whiteness and stiffness of the coating. The amount of ink required for a material with a large coating tension is relatively small, and the surface tension of the coating is small so that the amount of ink is greater than the shrinkage during the printing process. The tension of the different tinplate coating materials in the different changes in the ink required to have a corresponding change, in the same species with the same amount of the same price conditions, the material of the degree of tension, high degree of whiteness of the product, certain To adapt to print quality is better. The hydrophilicity of the quality metal plate surface of the printing plate base sand and the oleophilic property of the coating polymer resin film face the compatibility of the printing plate affecting the ink transfer and the layout ink balance. In the plate making process, the exposure and development will also be good or bad. Affect the performance of the printing plate.
4. Effect of ink balance on printing quality
The ink-and-wash balance is a relative balance rather than an absolute balance. During the process of high-speed operation of the equipment, both the pattern part and the non-pattern part of the printing plate are inked and water infiltrated. Therefore, ink emulsification will inevitably occur on the printing plate. If the amount of ink is not well controlled, it will inevitably deepen the ink emulsification, resulting in the printing plate, dirty version. When printing, the method of reducing the amount of ink to increase the amount of ink is usually used. However, sometimes the amount of ink is also reduced. In addition, the ink emulsification varies with the change of the environmental conditions. In actual production, the ink should be grasped according to the actual situation. The viscosity and the pH of the fountain solution control the amount of ink and the amount of water. The printing plate does not have to be pasted and the plate is not subject to product quality requirements.
5, the impact of printing pressure on print quality
The printing pressure is the pressure between the printing ink rollers, and the interaction force between the printing roller and the impression roller between the plate cylinders. It is a necessary condition for the ink transfer. The printing pressure is too small for the ink to transmit and the ink traces. When it is too strong, the printing pressure is too high, and the amount of ink spreads to the non-patterned part, making the dot gain serious and the image distorted. At the same time, it is also easy to make the printing plate and blanket resistant to printing force drop. (For example, the plate is easy to wear, the elasticity of the blanket is reduced, ghosting, overprinting is inaccurate, and the length of the plate becomes longer). Therefore, the mechanical pressure must be properly adjusted. Different amounts of tinplate require different printing pressures, and only suitable printing pressure can ensure uniform ink and uniform shade.
Fifth, the effect of prepress and post-printing processes on product quality
1. Before printing, you must check the equipment's surrounding environment, hygiene, and precautions before using the raw materials (the verification of the process, ink sequence, selection of tinplate, size and other inspections are correct and incomplete. Only in this way can production be performed to ensure quality accidents.
2. The influence of the post-printing process on product quality is mainly reflected in the product specification size, whether the inner tinplate is incomplete, whether the order is reversed, whether the packaging is firm and the appearance is neat and beautiful, and the post-printing processing process is also a non-negligible combination in the entire printing process. Process.
In short, there are many factors that affect the quality of printed products, but from the process point of view, the above-mentioned several main factors are likely to bring quality problems. Understand these factors and control, you can ensure the stability of the printing quality, reduce the need to avoid substandard products The emergence of the lower printing costs, improve competitiveness and efficiency, all of the above technical for reference.
Ao Ruijin Mao Wenxian