Use of printing plates.

1.   For cutting printing plates before mounting on a printing cylinder, it is necessary to use only a sharpened knife and not to allow cuts on the polyester base and its peeling from the photopolymer layer. Cutting of one side of the printing plates should be carried out in one continuous movement of the knife, in the "base up" position of the printing plates.

2.   Double-sided mounting tape must have adhesive properties that meet the conditions for use of printing plates. When mounting, the joints of the mounting tape and printing plates should be avoided. If the back side of the printing plates is treated with solvent before installation, wait until it has completely evaporated.

3.   It is recommended to use a rubber roller that creates the necessary pressure, but does not damage the effective surface of the printing plates, in order to ensure a uniform and tight fit of the printing plates to the mounting tape. There should be no air bubbles between the printing cylinder and the mounting tape, and also between the mounting tape and the plate.

4.   Do not allow debris or dust to enter between the mounting tape and the base of the printing plates. After gluing the printing plates to the printing cylinder, it is desirable to carry out additional sealing around the perimeter of the plate to prevent ink from flowing between the tape and the printing plate during printing.

5.   No sharp tools can be used to dismantle the printing plates. Dismantling should be started from the plate joint on the side parallel to the cylinder axis. Separation of the plate from the cylinder should be carried out at an obtuse angle avoiding the formation of creases. After removing the plate, it is necessary to remove adhesive residue from both the base and the surface of the printing cylinder with a solvent, and to clean the printing plates from ink.

6.   In the printing process, due to the contact of the printing plates with the ink, the photopolymer swells and the hardness of the printing plates decreases. To achieve a stable quality of color transfer during the circulation process, it is necessary to minimize the content of aggressive substances that cause swelling, including irreversible one.

 

7.   Various substances act as swelling catalysts depending on the ink type:

  • for alcohol-based inks, these can be acetates (as drying accelerators and binders) and moderators - ethoxypropanol and methoxypropanol;

  • for water-based inks, it can be antifoams, which are often produced on the basis of mineral oils;

  • UV-inks and agents for cleaning plates from UV-inks contain substances (monomers) that cause irreversible swelling of photopolymer forms, therefore, it is necessary to conduct additional compatibility testing for UV-inks.

8.   When using printing plates, the resistance of photopolymers to various solvents must be taken into account. For more information on the resitance, please see Referral Information section.