High Speed Inline Coating
for Sheet Fed Printing Presses
High Speed Inline Coating for Sheet Fed Printing Presses
 Preconditions
- up to 12,000 prints/h the usual
processing instructions are to be
observed
- for High Speed Inline Coating with a printing
speed of up to 18,000 sheets/h the processing
range must be adapted regarding
- substrate
- ink layer thickness
- coating viscosity
- coating selection
- performance of the dryer
- distance under the dryer
High Speed Inline Coating for Sheet Fed Printing Presses
 Substrate - Ink
- the combination of substrate and
ink should be selected in a way to
assure a good bond between ink
and substrate
- poor ink drying cannot be improved
by coating
- the result is bad rub resistance and
insufficient scotch tape resistance
High Speed Inline Coating for Sheet Fed Printing Presses
 Adhesion Substrate - Ink
Ink
Coating
Paper
High Speed Inline Coating for Sheet Fed Printing Presses
 Ink Layer Thickness
- Overinking of the ink layer thickness
with parallel inline coating will reduce
the performance of the printing press
- as by reducing the printing speed the
drying time is adjusted
High Speed Inline Coating for Sheet Fed Printing Presses
 Ink Layer Thickness
Normal Inking
Ink
Paper
Coating
Overinking
Ink
Paper
Coating
High Speed Inline Coating for Sheet Fed Printing Presses
 Cell Volume of the Screen Rollers
- the cell volume of a screen roller is indicated
with the scoop amount of water in ml/m²
- the coating application amount corresponds to
about 1/3 of the indicated cell volume of the screen
roller
Example:
A cell volume of the screen roller
of 15 g/m² corresponds to
approx 5 g/m² coating application
High Speed Inline Coating for Sheet Fed Printing Presses
 Gloss Diagram after 24h Drying
55
Gloss in %
50
Wet-onWet
Printing
45
3 g/m²
2 g/m²
40
1 g/m²
35
30
0
5
10
Drying Time in h
15
20
High Speed Inline Coating for Sheet Fed Printing Presses
 Coating Viscosity
- the coating viscosity
depends on the temperature
and is determined with a 4 mm
DIN cup at 20°C
- when the temperature in the
coating rises the viscosity will
decrease
- in case of a viscosity decrease, e.g.
below 25 sec., an even coating
application cannot be assured any
more
High Speed Inline Coating for Sheet Fed Printing Presses
 Viscosity depending on the Temperature
Viscosity in s
100
80
60
40
20
15
25
35
Temperature in °C
45
High Speed Inline Coating for Sheet Fed Printing Presses
Variable Coating Viscosities
Cooling Units for Coatings
by EASYLAC keep the
coating stable in viscosity
High Speed Inline Coating for Sheet Fed Printing Presses
 Too high Coating Viscosity
- a too high coating viscosity, e.g.
above 65 sec. can be adjusted by
dilution with water to the required
viscosity
- a too high coating viscosity in
connection with High Speed Inline
Coating will lead to splashing
High Speed Inline Coating for Sheet Fed Printing Presses
 Dilution of the Coatings with Water
80
Viscosity in sec.
DIN 4 mm Cup at 20 °C
70
60
50
40
30
20
0
4
8
12
approximate Water Amount in %
16
20
High Speed Inline Coating for Sheet Fed Printing Presses
Coating Selection
- the drying behaviour of
coatings depend on the
coating type
- if for example the following
coating types are used:
- matt
- semi matt
- protection
- gloss
- high gloss
- UV coatings
their drying behaviour will be
considerably different
High Speed Inline Coating for Sheet Fed Printing Presses
Coating Selection
Rule of thumb:
For dispersion coatings:
The higher the gloss, the
slower the thorough
drying
High Speed Inline Coating for Sheet Fed Printing Presses
Gloss Diagram: different coatings on the same substrate
90
Gloss in %
Drying time in s
80
70
60
50
40
30
20
10
0
Carton DL 1176 DL 1351
GD2printed
DL VP
385
DL 1200 DL 1300 DL 1150
DL 1650
DL VP
9756
High Speed Inline Coating for Sheet Fed Printing Presses
 Influence of the Surface Structure of the Substrate
80
Gloss in %
70
Carton 1
60
50
Carton 2
40
30
0
2
4
6
8
Application Amount g/m² wet
10
12
High Speed Inline Coating for Sheet Fed Printing Presses
UV Coatings
- UV coatings dry immediately by
photo-polymerisation using short wave
light
- the acetone test shows whether the
coatings have dried thoroughly
High Speed Inline Coating for Sheet Fed Printing Presses
Performance of the Dryers
- the drying behaviour of the coatings is
determined by the performance of the dryer
- the thorough drying of dispersion coatings
is primarily determined by the available
amount of air
 The more air, the better for the
thorough drying
- beginning at a pile temperature of approx.
35 °C problems may occur in the pile
High Speed Inline Coating for Sheet Fed Printing Presses
Drying of UV Coatings
- for UV coating processes the condition of the
UV lamps and a sufficient performance are
responsible for a good coating result
- the temperature in the pile is also decisive for UV
coatings and may be responsible for subsequent
problems in print finishing
- too high temperatures may result in breaking of the
printed matter during the grooving and folding process
High Speed Inline Coating for Sheet Fed Printing Presses
Drying Distance
An extended delivery between
coating tower and delivery is
advantageous for the printing
speed.
A short delivery is a disadvantage
for High Speed Inline Coating.
High Speed Inline Coating for Sheet Fed Printing Presses
Printing Press with Double Extended Delivery
High Speed Inline Coating for Sheet Fed Printing Presses
Special Coating Applications
- for special coating applications, as e.g.
application of blister coating, a coating
amount of 6 – 8 g/m² has to be applied in
order to assure good bonding with the
plastic foil
High Speed Inline Coating for Sheet Fed Printing Presses
 Result
High Speed Inline Coating with 18.000 prints/h will
not present any problems if the appropriate coatings
are used and the printing press is well adjusted.