PS version of the common problems in the printing process and solutions

The task of the PS version is to transmit the graphic part as accurately as possible to the blanket. Graphic part of the hydrophilic, non-graphic part of the ink. But in reality it is not so ideal. There will be various issues related to the PS version. Let us cite some of them and discuss them.

1, the layout of non-graphic part of the dirty, non-graphic part of the ink

The reasons are as follows:

A. The chemical composition of the fountain solution is improperly configured and erodes the hydrophilic layer of the blank portion. This is done by replacing the dampening fluid with a dampening fluid that is properly configured according to the manufacturer's instructions.

B. The roller sleeve of the plate roller is dirty or worn, damaging the blank surface. Treatment method: clean or replace the version of the water roller sleeve, wet wash can protect the printing plate.

C. Inking too much during halftone printing causes the ink to spread, which eventually sensitizes the non-graphic area.

Treatment method: Use thinner ink film for printing.

D. Sand with sandpaper on the rubber blanket is retained, and the printing plate is worn. Ball-buying measures: Clean the rubber cloth, change the paper; Add anti-accumulation agent to the fountain solution; Adjust the amount of water to the minimum, add more concentrate, gum arabic and or alcohol or alcohol substitute as needed Makes the printing plate non-graphical part to keep clean on the basis of reducing the amount of water; in the BB type printing, reduces the pressure between the printing plate and the rubber cloth. If an impression cylinder is present, the pressure between the impression cylinder and the paper should be checked; if the build-up occurs mainly in the first printing unit, the amount of water should be increased to help clarify the squash on the paper.

E, aluminum base oxidation. Oxidizes dirty and looks like a lot of clear dots or doughnut-shaped spots on the canal. It often appears in areas that have long been in contact with wet reel water rollers. Plates tend to oxidize if they are too slow to dry, or stored in moist places before development or during two printing runs. If the printing press breaks while the plate is not yet dry, the plate will also oxidize. Action: Follow the recommended plate handling procedure. Store plates in a dry place. During the plate making process, a cheesecloth is used to quickly dry the plate. In the printing process, such as parking, should rely on the printing roller to leave, open the empty car until the plate is dry.

F. Incorrect working of the water roller and ink roller in the ink system, may cause the print to appear dirty in the peripheral or axial direction. Measures: Check the pressure of each roller in the ink system, cleanliness, geometric accuracy, and overall condition.

G. Pre-exposure (grayed) occurs in the pre-printing stage of the plate. Measure: Store the plate in a light-proof box; install appropriate safety lighting equipment at the plate making site.

H. The ink is too soft or too oily. At this time, contact the ink manufacturer.

I. Excessive dampening solution causes the imprinting to be snow flakes; the ink color appears solid in gray, and the color is dark on the ground; in the zoomed-in state, the unevenness in the field is found, filled with tiny white spots. Excessive fountain solution emulsifies in the ink. When the ink film is split, the water droplets are exposed, and these water droplets hinder the transfer of the ink to the paper. At this point to reduce the amount of water supply.

2, PS plate part of the wear

There are two reasons: First, there are too many resins in the fountain solution; second, there is too much acid in the fountain solution. The solution is to re-allocate the fountain solution and check the pH.

3, the printing plate has white fibrous

This is mainly due to the fact that the paper fluff is too much or that the roll fabric is peeled off. The method is to clear the printing plate.

4. The graphic part of the plate cannot be properly inked

There are two reasons: First, the printing plate graphic area has cured resin or repair solution, so only hydrophilic is not pro-ink; second is the accumulation of ink on the roller, plate and rubber cloth is too short or Immersed in water.

The method is to wipe the plate with a damp cloth, reduce the amount of water, and protect the minimum amount of water needed to clean the non-graphical parts.

5. Graphic loss

The reason is that the pressure of the blanket cylinder and plate cylinder is too heavy. The processing method is to check the printing pressure.

6, the ink on the plate after baking is too slow

The reason is that the thermosetting layer is too thick. The treatment method is to wash with a phosphoric acid solution or wash with a plate cleaner.

7, there is a scratch on the plate

The reason is that the outer layer of the paper roll before the machine has a small sand, or small sand grains embedded in the surface of the printing roller. The processing method is to remove two or three layers of paper on the paper roll of the machine and clean the rubber roller.

8, plate cracking

The PS version may have cracks along the bay line at the end of the edition or the end of the edition. There are two reasons: One may be the wrong size of the plate. Does not evenly cling to the drum body. This may be due to inaccurate bending, plate movement on the plate bending machine, or serious wear of the plate bending machine; the other is that the printing plate is not clean in the slits, and residual ink makes the printing plate not installed properly. The head or the end of the layout is under severe stress.

The PS version plays an important role in printing. It consists of a photosensitive layer and a plate base. The photosensitive layer should have good lipophilicity; the plate base is a blank part and should have good hydrophilicity. PS plate should meet the following requirements: flat layout, uniform thickness, dimensional stability, not easily deformed, no dirt, scratches and defects on the surface, can firmly adhere to the photosensitive layer of glue and can not undergo chemical changes, after surface treatment Good hydrophilicity and abrasion resistance, high resistance to printing.