1. Optimized Drying and Curing Processes for New Functional Products
Dr. Kai K. O. Bär
adphos Digital Printing GmbH
Optimized Drying and Curing Processes for New Functional Products
NIR is a trademark of adphos.
adphos owns more than 200 patents- or patent applications on the NIR-technology
InPrint Show, November 10th, 2015 – Munich/Germany

2. Thin Layer Film Applications Functional Coatings and Treatment On
 1 µm to 0.1 mm
one/more
Wet/dry or gaseous or organic or non-organic coatings
InkJet
Roll coating (flexo, gravure, offset)
Screen
Curtain
Powder coat
PVD, CVD …
and
Treatment On
Substrates
in combination with
Drying
Heating (melting, sintering, deposition)
Curing (heat/radiation)
only on surfaces
Flat/cured/3D
Continuous/sheet/batch

3. Dry –
What is it?

4. H2O/solvent based UV coating?
What is Dry at
Drinks?
100 % UV-based coatings?
H2O/solvent based UV coating?
Thermal curable power?

5. Dry(ness) is not a proper quantified physical parameter!
Quelle:

6. Drying and Curing (Heating) Processes (1)
Starts with
Wetting and spreading at the surface
porous non-porous
Dehydration
Suction into substrate
Unforced drying by ambient evaporation over time
Removal of moisture/viscosity increase

7. Drying and Curing (Heating) Processes (2)
Fixing coating to substrate
Mechanical adhesion
Bonding
Over coating
Final coating treatment for functional properties
Curing
Sintering

8. Typical Todays Drying Technologies
Hot air driers
Hot drum/hot plate + hot air
(m)IR and hot air
(adphos)NIR®-dryer (with integrated high airflow rate, warm impingement air, air ventilation and removal)

9. Working Principles (1) Hot Air – heat transfer by heat convection
Complete surface is heated relying on conduction through the ink/substrate
Dries non-printed areas before all of ink pattern has been dried
Circulating air can help remove the water molecules from the surface
Air is generally heated outside of the drying system
Very slow drying process
Substrate
Hot air
Drying
heating by conduction

10. Required Power for Hot Air Dryers
Drying Power: ≙ Energy to heat up substrate mass + Energy to evaporate water (from ink pattern and removal of ambient moisture in the paper)

11. Working Principles (2)
Hot plate/heated drum – heat transfer by hot contact area (conduction)
From backside up approach
Heats the substrate before the ink film
Relies on conduction
Drives water up to the surface
High amounts of residual heat

12. Required Power for Heated Drum
Drying Power: ≙ Energy to heat up substrate mass + Energy to evaporate water (from ink pattern and removal of ambient moisture of paper)

13. Working Principles (3)
IR (Infra Red – Short, Medium To Long Wave) – only heat transfer to the surface by radiation
Top down approach
Heat absorption at complete substrate surface
Dries non-printed surface before ink patterns are properly dried
Relatively slow drying process

14. mIR is “color blind” for printed pattern
Midwave IR Heats Both the Substrate and Printed Pattern – Nearly Equal Absorption
mIR is “color blind” for printed pattern

15. Required Power of IR-Dryer
Drying Power: ≙ Energy to heat up substrate mass + Energy to evaporate water (from ink pattern and removal of ambient moisture of paper)

16. Working Principles (4)
NIR (adphosNIR) – heat transfer/process by Near Infra Read radiation
High energy density penetrates ink film drying from the bottom up
High energy density excites water molecules instantaneously
Paper substrates are highly transparent to NIR producing limited substrate heating
Emitters can be controlled across the web drying only areas being printed
NIR has a high energy density (ultra fast drying process)

17. NIR-Drying Shows High Absorption in the Printed Pattern

18. Required Power for adphosNIR®-Dryer
Drying Power: ≙ Majority Energy to remove (evaporate) the water from the ink pattern Remark: Substrate temperature rise results from heat conducted from the ink pattern and by minor direct absorption of NIR.

19. adphosNIR® allows Instantaneous setting of coating
stops spreading and penetration
Instantaneous evaporation of water and solvents
water removal and disruption of high boiling temperature humectants (e.g. Glycol)
Low thermal stress on the non-printed substrate
no dry out  no remoistening needs
applicable for thermal sensitive substrates (e.g. thermal paper, plastics, …)
no afterwards web cooling required
High dryer efficiency, enhanced print quality (higher color density, higher crisp) and improved speed range

20. Application Example (1) Enhanced Drying in Digital Printing Press
Speed:
120 m/min for all applicable substrates
Uncoated
Coated esp. regular offset
Up to 120 m/min only uncoated substrates
Up to 80 m/min limited to some coated substrates only
Energy consumption:
Depending on paper width, ink coverage,
paper type
40 kW to max. total 70 kW
80 – 100 kW
Flat products no remoistening
Wavy, strong dry out (needed 5 g/m² remoistening)
Drying length:
Total 300 mm
Total 1,200 mm

21. Application Example (2) Process Color Printing on Corrugated Boards
Speed:
200 m/min
Width:
1,300 mm
Total drying length:
1,500 mm
Alternative driers get “banana shape” boards
Low temperature (60 °C) air driers would require > 10 m
Requires extreme more drying energy (2.5 – 3 times!) compared to NIR
A = Pre-Treatment Driers
B = InkJet Driers

22. Application Example (3) Process Color Printing on Plastics
Speed:
50 m/min
Width:
2,500 mm
Substrate:
PP, vinyl and other plastics
Interstation dryer configuration
Only final dryer configuration results in intercolor bleeding
Here for no alternative driers with thermal inks are applicable

23. Application Example (4)
Ink Jet Printing of nano silver inks on PET/Paper
Hot air oven: °C °C
Midwave IR: 1 up to 150 °C
adphosNIR®: 1-4 up to 250 °C (coating) and < 120 °C at substrates
Xe-Flash: s depending on coating thickness

24. Application Example (5) Additive Manufacturing – 3D Printing
Speed:
Up to 30 – (60) m/min
Width:
Up to 2,000 mm
Materials:
Plastics, metals!
Special unique benefits with adphosNIR®-processing
Preheating of plastics only up to crystallization point
Metals can be processed from ambient
Instantaneous melting of “printed/coated” area
Width adjustable heating power
Powder reusable due to low thermal treatments
Quelle:

25. Conclusions Drying starts immediately with the coating drop down
Drying technology and configuration can strongly effect
coating process performance and
coating process quality and
coating process applicability (is do-able or not!) and
energy consumption and
mandatorily drives the costs of coated product
coating process costs
substrate costs (due to required type of substrate)
coating costs (consumption)
Coating process preparation and standby
total energy costs (startup, standby and print production, eventual cooling, remoistening, …)
adphosNIR® allows application optimized systems design and is already widely proven in coating processing

26. adphosNIR® shows large benefits and wide range applicability
Even though none of the today´s post processing technologies does fit for all –
adphosNIR® shows large benefits and wide range applicability
See us at our booth A6/G42 or at