Waterless offset printing technology common problems and solutions
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
Waterless offset printing is an environmentally friendly printing method because it does not use fountain solution and greatly reduces the emission of volatile organic solvents.
1, the back is dirty
The main reason for the dirty back is that the amount of ink is too large, the powder is insufficient, and the powder is uneven.
Solution:
Adjust the printing status to the best and reduce the amount of ink if allowed;
A dusting powder having a suitable particle diameter and distribution density is selected, and a distribution density of a dusting powder having a diameter of usually 20 μm or more is 5 to 10 pieces/mm 2 .
2, the delivery is not uniform
The reason for the paper being misaligned is that there is static electricity in the delivery section.
Solution:
Put a carbon cloth on the delivery roller;
Install a static elimination fan or an electrostatic bar in the delivery section;
Install a humidifier, if it has a humidifier, enhance its humidification function;
Install the static elimination rod at the final transfer roller, and clean the dust on the static elimination rod frequently. If it ages, replace it in time.
3, ink skin
The ink is mainly caused by paper powder, crust impurities of the ink, and the like.
Solution:
When there is ink on the watermark version, the operator can directly scrape off, and the water-free silicone layer is very easy to be scratched. If you don't pay attention, there will be scratches, which will cause the whole version to be scrapped, and the waterless offset It is also not possible to use a water roller having a function of removing the ink, so that in order to prevent the ink from reaching the printing plate, a de-inking roller can be installed at the first inking roller;
Replace the rubber roller that absorbs the ink difference;
Dry a solid strip at the mouth of the plate and attach the ink to the strip;
Non-graphic part plus solid ribbon, but pay attention to the back is dirty;
Thoroughly clean the ink roller and ink fountain, and replace the aging ink roller;
De-inking tools for waterless offset printing.
4, the pile of ink, the graphic part is missing
The main reason for the lack of ink and graphic parts is that the waterless offset ink has too high viscosity or the surface strength of the paper is too low.
Solution:
Select a waterless offset ink with a lower ink viscosity;
The temperature of the printing paper should not be too low. The paper should be sent to the printing workshop as early as possible to adjust the paper to the appropriate temperature.
Reduce printing speed (forced emergency response);
Clean the blanket and use the old paper that is not easy to cause the ink to be evenly distributed at the beginning of printing (the old paper should be reused many times, depending on the surface condition of the paper).
5, scratches
The abrasion is mainly caused by the tapping caused by the static electricity of the paper.
Solution:
Put anti-static tape on the paper-receiving roller to reduce static electricity caused by friction between the rollers and prevent the paper-receiving roller from sticking to the ink;
Install a static remover on the take-up reel.
6, ghost
Ghosts are mainly caused by poor ink flow. For some special patterns, it is more difficult to completely remove ghosts.
Solution:
Add color blocks outside the image to increase the fluidity of the ink;
Pay attention to the aging of the ink roller, and confirm that the pressure of the ink roller is within a suitable range;
Avoid excessive thickness of the ink layer and adjust the printing pressure and plate layout temperature to a suitable state;
When using imposition printing, if there is room for the printing layout, try to evenly distribute the position of the graphic;
In the case of not being dirty, it is allowed to have a certain amount of movement by the plate roller.
7, dirty
Dirty is caused by a decrease in ink viscosity caused by an increase in temperature of the printing press.
Solution:
When printing more than 10,000 pieces of work, the printing machine will continue to rise due to high-speed operation, and the surface of the printed sheet will gradually become dirty. In this case, it can be eliminated by lowering the set temperature of the cooler. Dirty, of course, it takes some time, the temperature of the cooler can be set separately according to the long version of the job and the short version of the job. For example, when printing a long version, after printing thousands of sheets, you can follow the long version of the job. The temperature standard reduces the temperature of the chiller, but this is not conducive to stabilizing the temperature of the printing shop;
Reduce the temperature of the printing machine, such as reducing the cooling temperature of the ink circulation part of the printing equipment, increasing the fluidity of the air around the printing machine by increasing the number of fans, and reducing the heat retention of the printing machine;
Increase air conditioning and refrigeration capacity;
Reduce the printing speed (forced emergency response).
8, color difference
Colors printed on waterless offset printing are slightly different from those printed by water printing, and it is necessary to perform color matching.
Solution:
When using waterless offset printing for printing and printing, if the color of the printed and reprinted printing is inconsistent with the printing with water printing (there may be changes in the publishing curve of water printing), first confirm that there is water printing. The curve is published, and then the publication curve of the waterless offset is adjusted accordingly (pre-made a number of waterless offset printing curves).
9. Poor surface smoothness
The poor smoothness in the field is mainly caused by the pressure between the printing plate and the blanket cylinder being too low, the viscosity of the ink is too high, the ink on the printing machine is dry, and the pressure of the inking roller is too small.
Solution:
Confirm that the pressure between the plate and the blanket cylinder is appropriate;
Replace the blanket with good smoothness;
Confirm the plate layout temperature and set the appropriate cooling temperature using the appropriate type of ink;
Confirm that the ink on the press is dry, if necessary, clean the ink roller or spray the anti-drying agent.