The “buckle rubber†phenomenon includes not only paper hair, paper powder, etc. that are buckled on the surface of rubber, but also paper hair, ink residue, etc. that are buckled on the printing plate. It is a headache for lithographers. It not only affects the quality of the product but also affects the production schedule. A slight carelessness can cause serious quality accidents.
First of all, we should analyze the reasons for the "buckle rubber" phenomenon. The analysis is as follows:
1. Paper: The surface of the printing paper is rough and soft, and there are many slags and powders on the surface of the paper. It is easy to adhere to the rubber.
2. Pressure: The pressure of the printing plate and the rubber cover is too light, and the paper hair and paper powder buckled on the rubber cover cannot be transmitted through the printing plate; the pressure of the rubber cover and the pressure roller is lighter, so that some fine impurities cannot be compacted on the paper surface. Walk away and remain on the rubber; the contact pressure between the printing plate and the printing roller on the printing plate is not real, and it is not possible to take away the paper residue, paper powder, etc. from the printing plate, and make the printing plate pile up ink, sticking slag, etc.
3. Improper padding: The plate or rubber pad is not even and uneven, and it tends to accumulate paper hair, paper dust, etc. in the lower position, resulting in partial buckle rubber.
4. Ink viscosity: ink viscosity is too large. Paper peeling force on the surface of the paper, paper on the paper, paper powder, etc. are easily hidden down, severe pull hair, peeling phenomenon.
5. Too much ink impurities: There are too many impurities in the ink in the ink fountain or too much paper on the roller, which is transmitted to the printing plate by the inner roller.
6. Uneven water supply: When there is water on one side of the water roller or there is a little water, the wear of the ink is increased compared to other places, causing the rubber to be buckled with less water.
According to the above six-point analysis, we should adjust the causes one by one to achieve:
1. Try to choose a paper with a solid texture, even pulp, and a smooth surface.
2. Adjust the contact pressure between the ink rollers, the contact pressure between the plate roller and the plate roller and the plate, and the contact pressure between the rollers.
3. Ensure that the ink is clean and free of ink residue, paper hair and other impurities, and stir the ink in the ink fountain. Clean the ink roller frequently and keep it clean.
4. Plates and rubber pads must be flat and clean.
5. The pressure should be slightly larger than normal printing. Try not to turn the pressure gauge so as not to affect the overprint. We have adopted a method of adding 0.09 to 0.15 mm backing paper in the rubber pad. For a two-color machine. The first color to increase the pad, the second color can be fixed. For four-color machines, one-color, two-color increase pad, three-color, four-color unchanged, one color should be slightly thicker than the two-color pad.
Doing so will cause the full-page change to be 0.01 to 0.02mm, which will not cause too much error in overprinting (Note: After adding the backing paper, the blanket should be pressed tightly, otherwise overprinting will be affected).
6. Appropriate addition of ink in the ink reduces the viscosity of the ink. General graphic products should be added 3% to 5% of the relieving agent and 1% to 3% of the varnish; For thick ink products in the field, it is necessary not only to add and remove adhesives and varnish, but also to add about 2%. Dusting powder; printing gold, silver plus 2% to 3% of the escaping agent, can also reduce the "buckle rubber" phenomenon. Light quality water roller should reduce the amount of material to avoid floating on the dirty; velvet water roller can increase the amount of attached department. For quality requirements, printing with coated paper should be minimized or not used to ensure that the ink is bright and shiny. Do not apply retackifiers for those that require hanging plastics.