As a printing factory, the
printing plate dirty is a common failure for printing services,
but in a sense it is a typical failure. In the process of production, specific
analysis must be carried out according to the signs and parts of the layout. In
the process of production, specific analysis must be carried out according to
the signs and parts of the layout, find out the cause of the failure, and take
effective measures to prevent and solve it. Generally speaking, the printing
plate dirty can be classified as tinting, oil dirty and so on.
1. Tinting
Tinting is a phenomenon of dirty a
relatively large and low density of non-graphic parts. It has no lipid base on
the dirty parts. Because of this, the non-graphic part of the tinting, visible
on the printed paper, may be visible on the printing plate, may not be seen. From
the surface of the printed matter, the dirty spots are sometimes floating
around, and there is a possibility that the first and the last dirty spots are
in different locations. In addition, the printed matter which have tinting the
ink was dull and dim.
The most important cause of tinting is ink
emulsification caused by ink imbalance. In addition, there are paper quality,
water, ink roller and printing pressure.
The specific causes and treatments are as
follows:
(1) The ink tolerance is insufficient and
emulsified in wetting liquid.
Treatment: for soft or thin ink to increase
the consistency of ink, water - wet short - silk ink is added.
(2) The emulsifying agent is precipitated
from the paper coating and causes the tinting.
Treatment: change paper or harden ink.
(3) in multicolor printing, if all kinds of
ink are dirty, it could be paper problems. If only one or two colors of ink occur
tinting and the other ink is printed clearly, it is a matter of printing ink or
printing plate. Monochrome machines have similar phenomena.
Treatment: change paper, harden ink or change
ink.
2. Oil dirty
Oil dirty is the printing plate should not
feel oil part feel oil, make the ink stick on it, form the printing plate
dirty. The main causes of the blank part of the printing plate feel oil: The
blank part of the water is not sufficient or the single wet solution is acidic,
or other causes destroy the hydrophilic layer of the blank part of the plate.
The biggest characteristic of oil dirty is:
The dirty parts are more fixed. And the dirty parts are not easy to erase, In
addition, use water with liquid medicine and peach gum can be eradicated, but
the oil with serious damage to the abscess cannot be eradicated.
The reason for the oil dirty in printed
matter is that the relationship with the printing plate and the relevant parts
of the friction are in doubt. Ex.:
(1) Printing plate/rubber cloth roller is
too much pressure.
(2) The ink roller pressure is too high.
(3) The plate is not tightened when
installed.
(4) The inks are lipid and the dosage of
additives is improper.
(5) The pH value of wetting liquid is too
high.
(6)
Rubber cloth is old and lack of elastic.
