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Frank De Voeght
10/11/2015
www.chemstream.be
10/11/2015 2
Core activities:
Innovative contract research
Customized product development
ChemStream’s profile
Translating customized requirements into chemical formulations with dedicated functionality, from design to prototyping:
Coatings Nano dispersions Inkjet inks
Chemical R&D Company:
10/11/2015 3
Ink design: Helicopter point of view
End user requirements Jetting performance
Functionality: Colorant Pigment nano dispersion Conductivity Hydrophobicity ….
Carrier design: Process/application driven Rheology Ink/media interaction Ink/printhead interaction …
10/11/2015 4
Customized requirements
Substrate
Ink design: Integrated approach
Printhead
System
Ink
Interaction diagram – Isolated environment
10/11/2015 5
Customized requirements
Substrate
xxxxxxx
Physics
Ecology
Legislation
Economy
Ink design: Integrated approach
Printhead
System
Ink
Interaction diagram – Open environment
10/11/2015 6
Designed by B̈ürkle
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10/11/2015 8
A dynamic iteration process between 3 sub processes: Chemical formulation process
System integrated process
Customer driven interaction process in an open environment
How to translate this dynamic iteration process in a lab workflow?
Ink development
10/11/2015 9
MPU: Modular Printing Unit
10/11/2015 10
Easy tool for feasibility research:
Mimic of an in line coating/printing process
Fast iterations of ink prototypes
Fast iterations with different printheads
Low investment level for customer
Ink/media interactions
Easy to provide test samples
MPU: Modular Printing Unit
10/11/2015 11
Printhead module
Transport belt
Curing module
Prototype ink
User interface
MPU: Modular Printing Unit
10/11/2015 12
Easy removal and/or addition of printheads with their appropriate driver electronics
MPU: Modular Printing Unit
10/11/2015 13
A variety of substrates:
Plastics
Metals
Textiles
Glass
DCP
3D Objects
...
PVC
DCP: Direct to Container Printing
Cotton Cu-Tube
Al-profile SiN/Glass
MPU: Modular Printing Unit
10/11/2015 14
Features ‘Down to earth’ printing system
Table top dimensions
No special infrastructure
Belt based system for single pass
Potential for crude multi pass
Small ink amounts
Flexible towards:
Head selection and replacement
Substrate height
Print strategies
Ink replacement
MPU: Modular Printing Unit
10/11/2015 15
Ink design: basics
End user requirements Jetting performance
Functionality: Colorant Pigment nano dispersion Conductivity Hydrophobicity ….
Carrier design: Process/application driven Rheology Ink/media interaction Ink/printhead interaction …
10/11/2015 16
Inkjet needs: Nano sized dispersions: mean particle size < 200 nm
No oversizers
Stable in low viscosity formulations
No sedimentation
Milling process: From raw pigment materials to nano dispersions
Dispersants: Stabilizing agent to prevent re-agglomeration during printing process and shelf life
Ink design:
chemistry of polymeric dispersants
10/11/2015 17
Molecular structure (Quinacridone)
Crystal Morphology
Detailed molecular interactions between the dispersant and the crystal surface can be calculated with high accuracy
Crystal surface
Polymeric dispersant
Molecular interactions
Ink design:
chemistry of polymeric dispersants
10/11/2015 18
Real pigment world is even more exciting: crystal surface contains steps and kinks
Kink sites = the place to be “Anchoring” sites “Receptor” sites “Catalytic” sites
Ink design:
chemistry of polymeric dispersants
10/11/2015 19
Design the pigment-anchoring chemistry of the polymeric dispersing agent or redesign the pigment surface
Design the colloidal-stabilizing chemistry of the polymeric dispersing agent
Design the optimal architecture of the polymeric dispersing agent
Synthesis of the polymeric dispersing agent / pigment particle surface
Evaluation in nano dispersion of pigment
Ink design:
chemistry of polymeric dispersants
10/11/2015 20
Smart choice of building blocks > Variety of physical properties
Ink design:
chemistry of UV curable inks
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monofunctional
difunctional
tetrafunctional
OH
O
NH2
O
O
O
OH
NH
O
O
O NH
O
n
NH
NH
O
OO
OOO
O O
m
m
n
n
OOO
O
O
O
N
Variety of functional groups
oligomers
polymers
acid
amide
hydroxy
small monomers
Building blocks of UV curable inks
Epoxy acrylate High T Resistance High hardness
Urethane acrylate High Flexibility > High Hardness Chemical resistance Scratch resistance Adhesion
Polyester acrylates All-rounders
Polyether acrylates Reactivity Abrasion resistance
Polyfunctional acrylates Cross linking density
Acrylate resins Variety of functionality
Ink design:
chemistry of UV curable inks
Thin film encapsulation inkjet ink with barrier properties printed on SiN
Patterned deposition of advanced functionalities on textiles
3D Printing with embedded functionality by printing UV-Led curable inks
10/11/2015 22
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Substrate (Glass)
Anode
Functional layers: electron transport,
emitting, hole injection
Cathode
Encapsulation
Organic layer
SiN
SiN
Organic layer
several layers on top of each other
TFE layers protect the functional layers from the environment to increase the lifetime
⋮
Inkjet
Inkjet
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Main functional requirements of organic TFE layer: Layer thickness: 2-4 μm
Water barrier properties
Good adhesion on SiN
Fast spreading and leveling properties
UV Led curable (395 nm)
High transmission in visible region
No yellowing after aging
10/11/2015 25
Ink Design: UV LED curable carrier based on low viscous monomers and functional oligomers
Fast spreading and leveling
Full coverage with max 4 levels of gray scale head
Low viscosity: <10 mPas
Surface tension: 30 mN/m and no dewetting
Cure Speed without yellowing
Low photoinitiator concentration
10/11/2015 26
Surfactants: fast spreading and/or leveling
Depending on the strong specific interaction between the polar head of the surfactant and the substrate, the surface becomes more hydrophobic resulting in dewetting
Low γlv
Low γsv High γsl
Wetting / Dewetting on high surface energy substrates like SiN:
10/11/2015 27
Oxygen inhibition has a negative influence on cure speed
0
10
20
30
40
50
60
70
80
5 50 500
%Co
nver
sion
FTI
R
Viscosity (cP)
Conversion rate of acrylate double bondingAtmospheric pressure
60s LED
30s LED
2s LED
Low viscosities are difficult to cure. TFE ink: 10 mPas !
Thin films are even more difficult to cure. TFE ink: 2-4 μm !
Oxygen diffusion penetration depth δ = ±1 μm after 1sec with (D= 10¯⁶ cm²/s)
10/11/2015 28
Curing in inert atmosphere increases the cure speed
0
10
20
30
40
50
60
70
80
90
0 200 400 600 800 1000 1200
%co
nve
rsio
n (F
TIR
)
vacuum pressure (mbar)
Conversion rate of acrylate double bonding:2s UV LED Exposure
0.5% TPO-L
3% TPO-L
10% TPO-L
10/11/2015 29
Fast spreading and leveling without dewetting: Low viscosity
Tuning the surface tension towards the surface energy of SiN
Taking into account the interactions of surface active materials with the SiN-surface
High cure speed and full cure without yellowing Low PI concentration and well selected monomers
Inert atmosphere (no oxygen inhibition)
Digital printing unit was integrated in the TFE-line
10/11/2015 30
High performance WB inkjet inks : o DOD (drop on demand) piezo
printheads (Seiko, Kyocera)
o Textile substrate: PES and PA
o Water and oil repellent
Concept: o Lotus effect (combining micro and
nano roughness)
o Fluoro alkyl siloxane + C6 fluoro alkane
o Fluoro surfactant and low viscous binder (viscosity modifier)
Case Study: Patterned deposition of advanced functionalities on textiles
Example of local deposition of functionalities on hiking shirt
Water repellent
Stain resistant
Anti microbial
A two-year Crosstexnet European project, funded by IWT in cooperation with UGent (TO2C), VdW-Consulting, TST, FOV and UBoras Project is focusing on new finishing techniques in textile industry
10/11/2015 31
Case Study: Patterned deposition of advanced functionalities on textiles
Functional performance (load dependent)
On PA:
o Water repellency and wash fastness: Excellent
o Oil repellency and wash fastness: Good
On Polyester:
o Water repellency and wash fastness: Medium – Good
o Oil repellency and wash fastness: Medium – Good
PA 3660
PES 8209
139° 143°
135° 140°
Load of active agent on the fabric 7,5 g/m2 15 g/m2
Printed fabric
Technical performance
Contact angles on printed samples: θ > 130° means (super) hydrophobic
10/11/2015 32
Multi pass mode
Printheads in line
Inks with different functionalities (matrix, functionality)
Process variety (wet on dry, wet in wet)
3D printing feasibility research with MPU
Case Study: 3D Printing with embedded functionality by printing UV-Led curable inks
10/11/2015 33
Law of Young Printing wet on dry:
Process Printing and curing matrix ink
Printing an curing functionalised ink
Printing and curing matrix ink on top
Dot size determined by; Drop volume
Law of Young (spreading)
Case Study: 3D Printing with embedded functionality by printing UV-Led curable inks
10/11/2015 34
γαβ
γβθ
γαθ
Neumann’s construction
Liquids: α, β, θ
Printing wet on wet
Process
Printing matrix ink
Printing and/or curing functionalised ink
Printing and curing matrix ink on top
Dot size determined by:
Drop volume
Law of Neumann (spreading)
Case Study: 3D Printing with embedded functionality by printing UV-Led curable inks
10/11/2015 35
Case Study: 3D Printing with embedded functionality by printing UV-Led curable inks
Multi pass mode 2 KM1024i printheads in line UV-Led curable (395 nm) Image visible with black light (365 nm) Process variety (wet on dry, wet in wet)
UV-Led curable fluorescent ink printed in 3D UV-Led curable matrix
10/11/2015 36
High performance inkjet ink development: a dynamic iteration process between 3 sub processes
Chemical formulation process
System integrated process
Customer driven interaction process in an open environment
Efficient implementation of these 3 processes in a lab environmental workflow during the whole ink development process (from design to prototype) leads to:
Short development times
Low investment level (during feasibility phase)
Dedicated high performance end user requirements
10/11/2015 37
Thanks for listening You are invited at our booth C45 for further information and discussions:
Els Mannekens
Frank De Voeght
More info on our website: www.chemstream.be