The relationship between the most pyrographic pape

2022-07-24
  • Detail

The relationship between printing paper, printing iron and PS plate

in the printing industry (whether printing paper or printing iron), PS plate, as the transmission medium of flat offset printing, is usually aluminum alloy plate with a thickness of 0.15~0.30mm, and a layer of photosensitive liquid is coated on the surface; The size can be selected or determined according to different application occasions and requirements. In the iron printing industry, the printing pattern is transmitted to the iron sheet surface by the water ink balance principle under the action of the appropriate printing pressure by the three rollers of the guide roller, the rubber roller and the embossing roller. The quality of the printing plate depends on the drying process of the PS plate and other influencing factors. It should be said that the printing plate quality is a prerequisite and fundamental for the quality assurance of printing products

this paper describes and discusses some details that should be paid attention to if PS plate is not treated timely and effectively in the drying process

ps plate drying process can be simply illustrated as three basic links, namely, exposure, development and glue protection

I. exposure

exposure is to place the PS plate coated with photosensitive layer on the workbench of the plate printer, place the negative film, and expose the pattern on the negative film to show the basic image on the PS plate through two exposures of main light and light transmission (the exposure conditions for PS plates of all simultaneous pieces are recommended: (1) a 3kW potassium iodide lamp is used as the light source; (2) Lamp plate distance 1m)

the working procedure of printing is automatic control, but the following basic details should be paid attention to, mainly including:

1. The tooth or bite position should meet the process requirements, and the edition should generally be centralized

(1) when the size of the printing plate is the same as that of the iron sheet, pay attention to the 1mm space in front of the plate and expose the cross hairs, and the + lines should also be exposed on the left and right sides

(2) if the size of iron sheet is surplus, negotiate with the customer about the blank position of iron sheet. For customers who have special requirements for iron surplus, they should comply with the corresponding standard requirements so that they can be reserved when printing

(3) when the size of the printing plate exceeds the size of the iron sheet, it can be exposed first and then cover the original position with the iron sheet for two exposures to remove the more images. These are special cases. Generally, plate making should be consistent with the size of iron sheet, which is both economical and reasonable and meets the process requirements

if 0.23712 512/mrt4 is used as the printing process of the tin crown cover, the size of the plate core is 712505mm2. When printing, the front of the plate position can be appropriately left 1~3mm blank, and the tooth position can be left 4~6mm gap (refer to the plate printing instructions of the primex-f450 printing machine of Fuji machinery in Japan for this example)

2. Before the power supply of the plate printer is started, check whether there are foreign objects such as a ruler and a plate repairing knife on the worktable, otherwise the glass frame of the machine will be exploded

3. After the PS plate is placed and the size is positioned, it must be noted that the vacuum air outlet on the side of the machine shall not be covered

4. Setting of exposure time: the main exposure time is usually set at 90~100s, and the light transmission is 15~20s

(1) if the exposure time is too long, the pattern on the PS plate is brittle, easy to fall off and lose some lines, and the printing plate has poor printing resistance

(2) if the exposure time is not enough, the pattern color will be light and empty

(3) when the performance of the lamp tube becomes poor for a long time, the exposure time can be appropriately extended or replaced

5. Taking the PS plate: care should be taken not to bend and make dead marks, otherwise the pattern is blurred, the ink color is empty, and the coloring is poor

II. Development

development the exposed PS plate is placed flat in the development tank to fully wet the developer with it. After about 1 minute, it is taken out and placed on the plate washing table. The dissolved coating of the plate is washed with water to develop the image. The following points shall be paid attention to during development:

1. The configuration ratio of developer and water. Generally, when purchasing the PS version, a certain developer shall be delivered with the version. The ratio of developer and water should be slightly greater than or equal to the use ratio of the original concentrated solution, especially in summer. If the developer concentration is too high, the effective points will be removed. If the concentration is not enough, the development time will be prolonged, which will easily make the layout dirty and affect the durability of the PS version

2. Control of development time. In general, it is appropriate to place the PS plate in the developer tank for about 1 minute (there will be obvious bubbles in the plate during development). Too long development time will remove the image on the layout, and insufficient development time will make the layout dirty

3. If there are any extra spots or images on the developed plate, it can be removed with revision paste, and then washed with clean water (when revising, you can dip a brush with an appropriate amount of revision paste and gently smear it on the more images or spots, and then stay for a while to wash them with water)

4. Development temperature. It is suitable to be carried out at room temperature (232 ℃). Too high room temperature will make the plate point reducibility worse; Too low temperature will reduce the developing ability

5. The development shall be carried out in a dark room to avoid natural light

III. glue protection

after development, some Arabic gum should be applied to the image and text parts and non image and text parts on the surface of the PS plate to prevent the printing plate from getting dirty and the plate from being scratched during the printing process. Although the plate protection work is simple and easy, attention should also be paid to the following two aspects during the actual operation time:

1. Glue cleaning

(1) after the developed PS plate is cleaned with water, use a rubber scraper or sponge to gently wipe off the excess water on the surface to apply glue. When applying, a cotton towel or sponge without depilation can be dipped with an appropriate amount of protective glue to wipe the panel in both vertical and horizontal directions, so as to be even and thin (if the coating is too thick, it is easy to peel off, and if it is too thin or uneven, it will not play a protective role)

(2) after the rubber is finished, put the plate on the workbench to dry (the fan can be used in summer, and the far infrared can be used in winter, which is convenient for storage and use. If conditions permit, the plate copying machine can be used for better effect)

2. Clear edition. For the printing plates that are reused, the ink on the surface can be cleaned with gasoline or ink cleaner, plate cleaning paste, etc. after each use to expose the primary color before gluing. In addition to paying attention to the above three basic links, the printing work also needs to understand the closely related common sense of daily plate protection and correction

(1) revision. Proofreading refers to checking and proofreading the negative film according to the original sample on the proofreading platform, mainly including: ① the size and specification of the manuscript surface; ② Core size; ③ Whether the layout + word lines and lines coincide; ④ Whether the picture and text lines are clear; ⑤ Whether the back of the negative is scratched (if necessary, the layout must be repaired with an opaque adhesive bag or a drawing pen, adding a pen or removing a pen)

note: the size of printing plate shall be consistent with that of iron sheet; The layout should have a + line and a center line, which are the basic signs of the standard version; The printing plate is usually marked with four basic marks: y, m, C and K (representing yellow, magenta, blue and black respectively), and there are 10% - 100% lines at the top of the plate to show the contrast between the sparse lines and the main pattern

(2) storage and protection of printing plates. ① Moisture and high temperature shall be avoided during the storage of PS plate. The recommended storage condition is 10 ℃ ~30 ℃, and the relative humidity shall not be greater than 65%. Otherwise, the PS plate is easy to be damaged by alkalization; ② The room shall be kept clean and dust-free to prevent direct sunlight; ③ When storing reusable printing plates, pay attention to the relative position of the plates. At the same time, it is best to separate the plates with paper liners in the middle; ④ In case of spots, scratches and other phenomena during printing, stop the machine to brush PS cleaning solution on the plate and add a small amount of fountain solution in the bucket to improve the printing resistance of the plate and obtain excellent printing quality

in a word, plate printing is an auxiliary work for the preparation of printing process. Although the process is relatively simple, the quality of printing plate is produced by Evonik products. The quality of printing products is directly affected by the quality of printing plate

based on the above, in the actual operation process, in addition to paying attention to the basic operation links in the automatic shutdown after the friction times of the printing process reach the set value and various factors affecting the printing quality, the position and role of the printing plate in the iron printing process can not be ignored, because no qualified standard plate, no matter how beautiful the pattern will not be presented

Copyright © 2011 JIN SHI