How much is the packaging offset? (106-110)

106. What problems should be paid attention to when using the automatic developing machine?

1 The developer should be warmed up and reach the set temperature before starting to use.
2 The developer's rubber roller should not have dry sand, so as not to scratch the surface of the plate. It is necessary to frequently clean the various rubber rollers in the developing tank, especially the rubberized rubber rollers, to prevent the rollers from drying and damage the driving motor.

107. What factors can cause soiling on the exposed PS plate?

There are two main factors:
1 There are dirt particles or dust and other foreign particles on the print glass and on the film.
2 hand-made collage of small negative film edge, transparent adhesive tape edge marks.

108. What are the differences in methods for dealing with dirt on different parts of the PS plate?

1 If there is excess light blocking material on the plate, since the solid part of the film is completely opaque, it does not affect the quality of the printing plate.

2 If the extra light blocking material is present at the dot site, or at the junction of the field, lines and blanks, it will leave dirt in these places. If the dirt removal agent is used, it is unavoidable to remove the image and text, so it can only be scraped with a scraper and the effect is naturally not good. If the dirt is serious, the plate can only be scrapped.

3 If the dirty spots appear in the blank area and there is a certain distance from the graphic area, it can be removed by removing the dirty agent.

Therefore, before the exposure of the printing plate, we must carefully check the position of the dot and the border between the graphic and the blank to ensure that no dirt occurs. When manually making the imprint, ensure that the edge of the negative and the adhesive tape do not appear on this part.

109. What kinds of methods are there for the PS version in addition to dirty prints? What should you watch out for when using it?

In addition to the dirty version of the PS version, there are two kinds of dirt removal membranes: dirty membrane removal and dirt removal.

(1) Diffusion Membrane Removal The scattering method utilizes a scattering film to scatter light during printing, so that the photosensitive material corresponding to the small spots and the dirty marks on the plate is irradiated with scattered light from various directions.

Remove dirt. This method will affect the reproduction of fine lines in the dots and graphics, thus affecting the quality of printed products. Therefore, the layout of the original with dots and thin lines, generally can not use this dirty method.

When printing text-only books and periodicals, it is common to output single-page negatives, and then collage on the transparent large-format basis. After exposure and development in the ordinary way, there will be a dirty mark around the single-page negative film on the printing plate and the corresponding part of the adhesive tape. It takes a lot of time to remove the dirty matter by a dirt removing agent method, and the dirt is removed by a scattering film. More effective.

The method for removing the dirty film is to divide the exposure into two times, the first is the main exposure, without the diffusion film, and the exposure time is about 4/5 of the normal exposure time; after the completion, the diffusion film is applied for the second time. In the sub-exposure, the exposure time is about 1/2 of the main exposure.

There are no or few dirty marks and fine spots around the PS plate, the small backsheet, and the adhesive tape that have been dried out in this way.

2 In addition to the dirty agent, the dirty method is to remove the dirt with a dirt remover that can dissolve the PS plate photosensitive coating. For the positive PS type and negative PS type, the corresponding dirt remover is used separately to remove dirt.

In addition to the dirty agent in addition to the dirty operation method is: After the plate is developed, remove the dirt agent with a brush, wipe the dirty spots and marks on the plate. Be careful not to let the dirt remover hit the graphic part of the plate or allow the dirt remover to penetrate into the graphic part. After removing the dirty, quickly remove the residual detergent and dissolved photosensitive material on the plate with water.

In addition to the benzene substances contained in the dirty agent, in addition to dirty operation should pay attention to the ventilation of the operating environment, try to avoid inhaling benzene substances or reduce the amount of benzene intake. In addition to the solvent in the dirty agent volatile, pay attention to the seal.

110. What is the use of baking version?

The positive PS plate uses the non-light-sensitive photosensitive layer as a graphic basis for ink. This photosensitive layer still has photosensitivity, and the resistance to alkali after light is poor. After the baking treatment, the molecular structure of the photosensitive layer can be changed from linear to mesh, losing photosensitivity, thereby enhancing the stability, corrosion resistance, and mechanical strength of the graphic part and greatly improving the printing plate's resistance to printing.

Whether you need to bake version depends on the number of prints. In general, printings with less than 50,000 impressions can be printed on the PS plate in the usual way. This does not require additional baking process. Because the photosensitive layer of the dirty parts after baking will be cross-linked and solidified, it can no longer be dissolved in the dirt removing agent and cannot be revised. Therefore, the baking must be performed after thoroughly removing the dirt.

Source: Printing Technology