Pad printing ink
The process of pad printing ink transfer is briefly described as follows: first pour the oil pan into the oil pan, and then the ink will be coated on the surface of the printing plate driven by the inking device; the scraper will scrape off the ink coated on the surface of the printing plate, as shown in the figure The ink in the text will remain in the pit; the pad printing head moves to the top of the printing plate to stick the ink in the pit of the printing plate; the pad printing rubber head moves to the substrate to print the ink on the product surface.
The process of pad printing ink filling the pits of the printing plate requires that the pad printing ink has good fluidity and cannot be dried before the pad printing rubber head is dipped; after the ink is dipped by the pad printing head, it must be ensured that the ink has sufficient plasticity, that is, the ink cannot There are changes in form. The transfer of ink on the surface of the rubber head is similar to the release state of the thermal transfer film, which must be completely transferred without major changes.
Pad printing ink requirements:
1. Fast and stable drying. Compared with screen printing ink, the drying speed of pad printing ink is faster. If the drying speed is too slow, the transferability will be affected, but this is relative. If the drying speed is too fast, the ink will dry on the printing plate. deep. In addition, it is very important for the pad printing ink to have a more stable drying speed range. When the ink is brought from the oil pan into the printing plate, transferred to the surface of the rubber head, and printed on the surface of the product, the amount of ink transferred is very small. To ensure the stability of printing suitability, the ink must maintain a stable drying speed, so the purity of the solvent in the pad printing ink should be higher than that of the screen printing ink.
2. The color concentration of pad printing ink is higher. The ink layer of pad printing ink is similar to that of offset printing. In order to obtain brighter colors, the color concentration of the pigment in the ink must be high, but too high a color concentration means that the adhesion will decrease. Obviously, we will have to refine the molecules of the pigment And choose better resin to make up for this deficiency.
3. Pad printing ink has more stable colloidal properties. Ink is a kind of suspension, and it will appear delamination when it is left for a long time. A uniform amount of ink is obtained on the head surface, which is similar to offset printing ink properties.
Marabu Pad printing ink
Although screen printing ink is able to be used by the pad printer. Appropriative pad ink is recommended by the pad printing expert because of steady surface tension and nice ink transfer result. There are three kinds of pad inks in Chinese pad printing market.
This glossy pad printing ink is distinguished by particularly high resistance. Being an one-component ink, it is very quick-drying and easy to be processed. To raise surface stability or other stabilities, hardener can be added. This pad printing ink can be widely used. On rigid PVC, polystyrene, ABS, acrylic glass, polyester, thermosetting plastics and varnished surfaces. Because of its high resistance, it can also be utilized for products subject to high mechanical stress, the effects of hand perspiration or cleaning agents, such as control knobs, camera housings etc. Under certain circumstances, this ink is also suitable for poly-acetal materials.
High-gloss, quick-curing two-component ink for high-demand adhesion, scratch resistance, mechanical and chemical resistance. By using a matte paste, the degree of gloss can be varied. Materials that are difficult to print on, such as pre-treated polyethylene and polypropylene, thermosetting plastics, metals and varnished surfaces, but also polyurethane, polyamide, melamine resins, powder-coated surfaces and suchlike are easily printed. It can also be used for polyacetal under certain circumstances.
Glossy, quick-drying pad printing ink with good resistance to many chemicals such as oils, greases, alcohol. Hardener can be added to further raise surface stability and other properties. Tampapol TPY is primarily used for printing on packaging made of pre-treated polyethylene and polypropylene, ABS as well as rigid PVC. It is also widely used for thermosetting plastics, metals and varnished surfaces.
The UV-curable pad printing ink Tampacure TPC is particularly suited to print onto
By adding hardener, TPC adheres excellently to
many other substrates such as
Pre-treated polyethylene (PE),
Pre-treated polypropylene (PP),
When printing onto metals, an addition of
Adhesion Modifier UV-HV 1 may improve the
adhesion of the ink. In the case of printing onto
polyethylene and polypropylene, please make
sure to pre-treat the surface of your substrate
by flaming or Corona discharge as usual.
As per our experience, you can achieve a good
adhesion with the Tampacure TPC with a
surface tension of at least 48 mN/m. On polypropylene,
you can also apply a thin film of our
colourless Primer P 2 for surface pre-treatment.
Since all the print substrates mentioned may be
different in printability even within an
individual type, preliminary trials are essential
to determine the suitability for the intended
The UV-curable Tampacure TPC is particularly
suited when printed parts are immediately to
be processed further, resp. when excellent
mechanical and chemical resistances are
With multicolour printing, it is important to
note that Tampacure TPC can be printed weton-
wet, without an intermediate UV-curing.
When printing overlapping motives with
opaque colour shades, however, the individual
ink films must be cured one by one.
If the different ink layers do not overlap, it is
possible to cure all printed layers with one
single pass through the curing unit. Due to
their transparency, 4-colour process shades can
also be cured with one pass through the curing
unit. Nevertheless, preliminary tests are always
According to the required curing speed, a UVcuring
unit (medium-pressure mercury lamps)
of 80-120 W/cm is necessary.
The curing speed of the ink is generally dependant
upon the kind of UV-curing unit
(reflectors), number, age, and power of the
UV-lamps, the printed ink film thickness,
colour shade, substrate in use, as well as the
The adhesion of the ink is usually tested by a
tape test after the ink has been cooled down to room temperature (approx. 20° C).
UV Pad Printing ink contains solvents. Parallel to
physical drying and the evaporation of the solvents
used, the actual hardening of the ink film
is caused by a chemical cross-linking reaction
started by the UV-light. UV Pad printing ink
is a slightly post-curing UV
ink which will achieve its best resistances after
24 hours. If hardener has been added, the
curing speed will be reduced. Due to this,
adhesion and scratch resistance should be
tested only after 24 hours. A final curing of the
ink film will be reached after approx. 48 hours.
The pot life (processing period) at room
temperature (approx. 20°C) with hardener will
be about 12-16 h. Higher temperatures reduce
pot life. . If the mentioned times are exceeded,
the ink's adhesion and resistance may be
reduced even if the ink characteristics show no
When using hardener, the processing and
curing temperature must not be lower than
15°C as irreversible damage can occur. Please
also avoid high humidity for several hours after
printing as the hardener is sensitive to
Pigments of medium to high fade resistance are
used in UV Pad printing ink. Owing to this, all UV Pad printing ink
shades are generally suited to a short-term outdoor
use of up to one year related to the
moderate Central European climate.
After proper and thorough drying, the ink film
exhibits outstanding rub and scratch resistance
and is resistant to a large number of chemicals,
oils, greases, and solvents, as well as
perspiration. These resistances can further be
improved by adding 5% hardener.
UV pad printing ink is not press-ready and must
therefore be adjusted to the required viscosity
with the corresponding thinners prior to
printing. In the case of higher requirements to
the ink’s resistance or reactivity, there are
different additives available.