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:

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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 …

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Customized requirements

Substrate

Ink design: Integrated approach

Printhead

System

Ink

Interaction diagram – Isolated environment

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Customized requirements

Substrate

xxxxxxx

Physics

Ecology

Legislation

Economy

Ink design: Integrated approach

Printhead

System

Ink

Interaction diagram – Open environment

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Designed by B̈ürkle

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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

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MPU: Modular Printing Unit

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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

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Printhead module

Transport belt

Curing module

Prototype ink

User interface

MPU: Modular Printing Unit

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Easy removal and/or addition of printheads with their appropriate driver electronics

MPU: Modular Printing Unit

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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

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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

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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 …

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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

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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

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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

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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

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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

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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

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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

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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:

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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)

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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