The wide application of labels and the continuous development of label varieties naturally promote the development of label printing technology. Label printing covers all printing methods such as flat, convex, concave, and net, and the application situation of each country is different. However, from the development trend of global labels in recent years, it can be seen that flexographic printing, narrow web printing, and digital printing have become new bright spots in label printing in European and American countries, as well as the development trend of label printing.

In 2012, the output value of label printing in my country was 19 billion yuan, and the output was 2.5 billion square meters, a year-on-year increase of 20%; in 2011, the output value of label printing was 23 billion yuan, and the output reached 3 billion square meters, a year-on-year increase of 20%. my country's label printing industry has achieved rapid growth with the development of the market economy, especially the rapid development of daily chemicals, food, detergents, medicine, cosmetics, household appliances and small household appliances, supermarkets, logistics and other industries. After several years of development, The label printing industry chain has been formed. According to a survey conducted by Qianzhan.com, in 2011, the capital's publishing copyright work will accelerate the transformation of its development mode, using mechanism innovation as a breakthrough point, continuously deepen reforms, accelerate resource integration, promote the integration of high-tech and publishing industries, and innovate and improve the public cultural service system of press and publication. Optimize the government management model, improve the service level, and strive to create a new situation in the capital's publishing and copyright work. From the "2013-2017 China Label Printing Industry Market Research and Investment Forecast Analysis Report" as of the end of November 2012, the revenue of the press and publishing industry in Beijing reached 46.617 billion yuan, a year-on-year increase of 9.45%; total assets reached 93.515 billion yuan, a year-on-year increase of 8.74 %; The total profit is 3.059 billion yuan; more than 115,800 employees are employed. The total revenue of the press and publishing industry ranks fourth among the 9 major areas of the city's cultural and creative industries.

Label printing covers several main printing methods. In the plate-making stage, different printing methods are selected according to the nature of different products, and the plate-making process is also different for different printing methods.

The process flow of flexographic plate making is: manuscript-film (negative film)-exposure-washing-drying-post-processing.

1. The manuscript design suitable for flexible printing should have the following characteristics: more colors, but less overprinting; no need to reproduce particularly small details; the network line is not too high, but the color printing effect can be obtained; it can be online for packaging processing.

2. Film (yin film). It meets the requirements of plate making, with clear pictures and texts, accurate dimensions and specifications; with matte film, the density of the four corners of the film is required to be the same; using medical film positive characters; measured with a transmission densitometer, the white level density is below 0.06; the black level density is above 3.5.

3. Exposure includes back exposure and main exposure.

Label printing

①, back exposure. The support film of the photosensitive resin plate upwards and the protective film downwards are laid flat in the exposure drawer to receive exposure. Ultraviolet light penetrates the support film to cure the photosensitive adhesive layer. To establish a stable base, the washing depth can also be controlled to strengthen the bonding force between the support film and the photosensitive resin layer. The back exposure time is determined according to the required substrate thickness.

②, the main exposure. Also known as front exposure, the photosensitive resin plate supporting film faces down and the protective film faces up. Lay it flat in the exposure drawer. Tear off the protective film once in a row, and then stick the film surface on the photosensitive resin plate. The vacuum film flat female 1 is not a high yield * Female A inspection method is covered on the film (non-medicinal) The film is evacuated to make the film and the photosensitive resin layer adhere tightly. Ultraviolet rays pass through the vacuum film and the transparent part of the film to polymerize and cure the photosensitive part of the plate. The length of the main exposure time is determined by the plate model and the strength of the light source. The exposure time is too long If it is too short, the slope of the picture and text will be too straight, the lines will be bent, and the small characters and dots will be washed out. On the contrary, if the exposure time is too long, the version will be applied and the writing will be blurred.

If there are large, small, thick and thin lines on the same printing plate, cover them with black film as appropriate and expose them separately. Small parts will not be lost due to washing to ensure the quality of the printing plate.

4. Rinse. The non-sensitized part is washed and dissolved, and the photopolymerized relief is retained. The length of the plate-washing time is determined by the thickness of the printing plate and the depth of the print. If the washing time is too short, unsensitized resin will be left on the plate, which will affect the depth of the plate. If the washing time is too long, the plate will swell, resulting in deformation or fine parts. Fall off.

5. Drying. Remove the washing solvent to restore the original size and thickness of the printing plate. The baking temperature is between 50-60℃. The baking time is determined by the thickness of the plate and the length of the washing time, generally two hours for thick plates and one hour for thin plates. If the baking time is too long and the baking temperature is too high, the printing plate will become brittle and affect the printing life. If the baking temperature is too low, the drying time will be prolonged. If the baking time is too short, the plate will be rotten during printing.

6. Post-processing. That is, debonding and post-exposure. The photosensitive resin is completely hardened (polymerized) to reach the required hardness index, and the viscosity of the printing plate is eliminated to facilitate the transfer of ink. The post-treatment time is obtained from the test, and the purpose is not to crack or stick.