How can I improve the printing level of inks?

The fact is,
, in most cases, leveling agents do not improve the printing leveling of inks
. According to our many years of application experience, ink leveling problems can not be solved by leveling agent alone.is a leveling agent? Leveling agent is generally used in coating formulation, the main role is to promote the flow and leveling of coating liquid on the coating surface, especially in the coating drying process to adjust the surface pressure in a uniform and low level, eliminate the difference in surface pressure, inhibit the formation of Benaud vortex, the thicker the coating film (e.g. 100 m), the more the need for leveling agent to play this role, so that the solvent can be evenly volatile throughout the surface, to achieve smooth and even bright surface .
a similar smooth surface, but also the effect that print pursues. Therefore, when the print appears water marks, mottled or shrink holes and other defects, the first reaction can be solved by adding leveling agents to the ink.
1: The red ink printing sample with poor printing level
this judgment is inaccurate. Compared with the coating,
ink is characterized by a thin film thickness generally
, after the film thickness is only about 5 m, the drying process solvent volatile effect is smaller,
at this time the ink "flat" may be more depends on its spread on the substrate,
at this time the use of leveling agent can not be a good solution to the flattening of the ink.
should
the Q2 problem of improving the "flattening" of gravvy inks?
1. Printing conditions
the depth of the plate, the angle of the mesh and other parameters and printing speed. General plate is relatively shallow, the number of lines is relatively large, flow level is good. At the same time, the layout of the trench and mesh wall, the angle of the net hole, etc. will affect the flow level of ink. When printing speed is fast, flow level is also better.
2. Ink viscosity and fluidity
the general ink viscosity is relatively high, printing level is better. However, the viscosity is too high, and when the printing speed is too fast, it also affects the printing suitability of the ink.
3. Wetting of the substrate by ink
this is common in water-based inks, the surface pressure of the ink must be lower than the surface energy of the substrate. When the ink sheet is relatively high, printing ink on the substrate can not be very good spread, resulting in shrink holes and other defects.
Q3
to improve the "flat" problem of gravvy inks?
1. Improving printing
suggests increasing printing viscosity and printing speed, and increasing the speed of plate network lines.
2. Improves the viscosity and fluidity of the ink
(1) select the right resin and pigment.
the smoothness of the actual ink depends to a large extent on the wetting and stabilization effect of the resin on the pigment. Ink flow is not good reason is often the interaction between pigments affect the flow of ink, so light oil generally rarely has a bad leveling problem, the more pigment powder in the ink system, the more difficult the level.
example, the printing ink with nitride cotton dispersion is better, printing with chlorine vinegar or polyether resin is better.
(2) add a suitable dispersant.
improves the wetting and wrapping of pigments, reducing the interaction between pigment powders, thereby improving ink flow and improving ink printing leveling.
2: Pigment-to-pigment interactions affect ink flow and leveling
e.g. TEGO® Disperse 760 W, ZETASPERSE® 182 recommended for water-based ink improvement, TEGO® Disperse 675 recommended for solvent inks, etc. Examples of applications such as:
Figure 3: ZETASPERSE® 182 Application in water-based flexible version
3. Improve the wetting of inks to substrates
For water-based gravate inks, by adding substrate moisturizers, reduce the surface pressure of the ink, improve the spread of ink on the substrate. Based on our application experience, the following wetting agents are recommended to solve the wetting problems of different substrates.
(1) for absorbent substrates,
such as general paper inks, TEGO® Wet 5XX (TEGO® Wet 500 or TEGO® Wet 510 series or SURFYNOL ® series (SURFYNOL® 104, SURFYNOL® 420, SURFYNOL ® 440).
Figure 4: 0.3% TEGO® Wet 500 (left),
Blank (right)
(2) for non-absorbent substrates,
Common substrate moisturizers can not meet the requirements, you can use high-performance substrate moisturizer DYNOL® (810/604) series. In the following water-based graved inks for BOPP printing, it can be seen that DYNOL® 604 and DYNOL®810 are much better used here than SURFYNOL® 104E. DYNOL ® 604 performance, DYNOL ® 810 cost-effective. Of course, this is not to say that SURFYNOL ® can not be used in water-based plastic inks, which depends mainly on the performance of the main resin in the ink and the amount of solvents.
5: BOPP printing water-based gravvy inks add xx% DYNOL® 604, DYNOL® 810, SURFYNOL® 104E
(
3) for some particularly difficult to wet the substrate
(e.g. poorly processed PP), DYNOL® can not completely solve the problem. Silicone substrate moisturizer TEGO® Wet 2XX (TEGO® Wet 240 and TEGO® Wet 245 are recommended to reduce static surface stress better, while dynamic surface stress is moderate. The following explains why
TEGO ® Wet 2XX
for this application.
generally speaking, silicone substrate wetting agent because of the molecular weight is relatively large, so the static surface pressure is better, the drop dynamic surface is not very good. The figure above is a dynamic chart tested with a bubble method, you can see that the traditional silicone substrate wetting agent TEGO® Wet 270, TEGO® Twin 4100, competitors in the drum speed is relatively slow, the test results are relatively high. TeGO ® Wet 245 because the molecular weight is relatively small, good compatible, so the surface stress by the velocity of the bubble is relatively small. Second, the lower dynamic table is better than TEGO® Wet 240, it is more unstable than TEGO® Wet 245 bubble, good stability, lower static table.
below is TEGO® WET 240 application of PVC water-based wood-printed printing inks
Figure 6: PVC water-based wood-printed printing inks added 1% TEGO® WET 240 (left), competition (right)
.