Some Experiences in Quality Control of Flexographic Printing

Shaanxi Zhongbao Printing Co., Ltd. mainly prints labels, cigarette labels, instant noodle boxes and other packaging and printing products. The company has all used domestic ink (Shaanxi New Century Company's products) for printing, and also won a premium product in the national quality evaluation of flexo products in 1998. According to the practice of the past few years, talk about quality control experience.

First, the rational use of anilox roller

Flexographic printing is particularly important for properly and properly using an anilox roll. In the lithographic printing, the number of lines of the anilox roller is generally high, ensuring that the opening area of ​​the black hole is smaller than the dot area of ​​the smallest area on the printing plate. Generally, the number of lines of the anilox roller is 3-5 times that of the printing plate network cable, and it is preferable to control the ink supply amount to be less than about 5% of the actual printing ink volume. In order to make the anilox roll have accurate ink transfer amount, it must be ensured that the anilox roll is cleaned regularly. There are various cleaning methods such as burning, punching, brushing and sticking. In order to prevent poor smoothness of printing materials and poor printing, use colorless water-based gloss oil and water-based diluting agent to make the printing effect better. In addition, try to use a small plate roller, so that the plate roller and the anilox roller can have more contact, reduce the large plate roller caused by the ink on the plate in the phenomenon of dry paste.

Second, we must pay attention to color network cable production

When the flexible version of the color screen printing is manufactured, problems such as gradation compression, tone reproduction, and gray balance must be considered in the process of color separation of the screen in order to adapt to the characteristics of the flexographic printing.

There are many factors that cause dot gain in the flexographic printing process, such as the accuracy of the printing press, the rationality of the ink supply, the adjustment of the printing pressure, the quality of the printed material, the control of the ink viscosity and the pH value, etc., and should be based on the actual situation in production. Make a corresponding dot-up curve.

Third, control the expansion of outlets

Controlling network expansion is a key issue for the success of flexographic printing. In flexographic printing, the minimum pressure is particularly emphasized. The elasticity of the printing plate is a favorable aspect of the flexographic printing, but controlling the pressure of the flexographic plate is a more difficult aspect. As a result of the dot enlargement, the bright light darkens and the dark tone becomes the actual ground. When adjusting the printing pressure, the pressure of the anilox roller and the plate roller should be as low as possible while ensuring the overall pressure consistency of the printing press.

Fourth, master ink application

More than four years have been all used domestic ink printing, has been applied very handy, the main key to good use of ink is to control and maintain a good ink viscosity and pH value, good use of ink additives, good grasp of the law of ink changes. According to the ink manufacturer's technical specifications provided by the general requirements for operation, different environments and substrates smoothness, ink absorption, to make appropriate adjustments. The ink that has exceeded the shelf life must be used with caution and reasonableness.