Self-healing additives in coatings

Shared research programme
Thermal reversible covalent cross-links

Todays event
Daniel
High Temperature Self Healing
Industrial Parties present:
June 03, 2015
2

TEAM Diels-Alder:
Daniel Turkenburg
Jan Willem Slijkoord
Hartmut Fischer
Corné Rentrop

Background:
• Self Healing coatings
• 15 years experience
• Strong knowledge position in the Netherlands
• Participation in various platforms (IOP, FP7, Horizon 2020)
• Common interest throughout the value chain:
• Chemical companies,
• Resins companies,
• Paint companies,
• End users
• Large interest in Diels Alder chemistry
• 19 companies
• 21 attendees
• Interest from university, SME, Large Enterprise

Goal:
Defining Shared research project to boost
Diels Alder chemistry in coatings
applications
Focus points:
1. Shared Research programme
2. Diels Alder Chemistry
3. Utilisation in coatings
4. Involve total supply chain

Intermezzo: Vitrimers
Thermoplast Thermohardener
Thermo-reversible polymer network

Agenda
10.00: Welcome and goal meeting– Corne Rentrop
10.10: Who is Who? Introduction of all participants (name, company, role)
10.20: Status self-healing coatings & Diels Alder chemistry - Hartmut Fischer
10.50: Coffee break
11.10: Shared research: how does it work - Jan Willem Slijkoord
11.30: Interaction: Round table discussion to identify industrial needs – ALL
12.30: Lunch
13.00: Summary round table & project set-up – Corné Rentrop
13.45: Next steps - Jan Willem Slijkoord

Reversible Crosslinking – Other Applications
• SH COATINGS
• Recycling of plastics
• Encapsulants which open at elevated temperatures
• Changes in solubility/viscosity at high temperatures, sensorics,
• Thermally removable adhesives
• Reversible data storage medium…
• …

Status self-healing coatings & Diels Alder
chemistry
Hartmut Fischer

Low temperatureHigh temperature
Diels Alder chemistry Thermoset
properties at
low
temperature
Thermoplastic at high
temperature so potential
to recycle
Various methods to introduce in coating
(Grafting to resin, (partially) replacing
“traditional” curing, Use as and additive

Selection of materials
Diels-Alder
Furfuryl and Maleimide
Simple / commercially available
Aromatic / rigid structures
Windblade coating systems
Poly urethane
(Epoxy)
Furfuryl alcohol Bismaleimide
Diels-Alder
Solid
Poor solubility
Prone to side reactions

Careful consideration
Order of reactions
Conditions for each step
Activate selective reactions, but
Avoid side reaction at high temperatures
HO – R - OH
Isocyanante polyol

Stereochemistry of DA- reaction
Possible stereo-chemical configurations
Consequences for switching temperatures:

Self-repairing Materials –
Thermally Re-mendable Cross-Linked Polymeric Materials
Use of a thermally reversible formation of covalent bonds to repair
fractures upon heating of the structure until “disconnection” occurs and
cooling to temperature of use where “re-connection” and healing occurs.
Reversible Diels-Alder reaction used for the crack
healing mechanism
Result of the crack healing: Sample
before after temperature treatment.
Partial recovery of the mechanics after repair.

O
R
N
O
O
R'O
R
N
O
O
R'
N
O
O
O
R
O
O
O
N
N
O
O
O
R
O
O
O
N
N
O
O
O
R
O
O
O
N
N
O
O
O
R
O
O
O
N
N
O
O
O
R
O
O
O
N
N O
O
O
R
O
O
O N
+

‘Thermally re-mendable cross-linked coatings’
Powder coating business case
Tunable properties of the binder material:
type & combination of monomers
concentration functional groups
molecular weight
CH3
C CH2
O
O O
O
O
CH2C
CH3
n m
+
Storage stability (glass transition temperature)
Processability (melt flow & wettability)
Mechanical properties (flexibility – hardness)
0246810
δ (ppm)
CH3
C CH2
O
O O
O
O
CH2C
CH3
n m
1
1
2 & 3
2
3
4
4
5
7
6
CDCl3
66
7
8
9
10
5
5
8 9
10
* High concentration of monomer in the reaction mixture; 50wt% instead of 20wt%
# Slightly different polymerisation procedure with respect to reaction time
Table 1Copolymerisation of FMA and BMA
Monomer
feed ratio:
FMA:BMA
Mn PDI FMA
composition
from NMR
BMA
composition
from NMR
Tg
mol-% kg·mol-1
mol-% mol-% °C
A 10:90 12.5 2.4 10 90 28
B 15:85 15.0 2.4 15 85 31
C 15:85 #
34.0 3.8 15 85 38
D 30:70 #
72.0 3.5 30 70 43
E 10:90 * 19.9 3.0 9 91 33
F 15:85 * 16.8 3.2 14 86 29

Tunable properties of the powder coating base material:
O
R
N
O
O
R'O
R
N
O
O
R'
N
O
O
O
R
O
O
O
N
N
O
O
O
R
O
O
O
N
N
O
O
O
R
O
O
O
N
N
O
O
O
R
O
O
O
N
N
O
O
O
R
O
O
O
N
N O
O
O
R
O
O
O N
+

1E+2
1E+3
1E+4
1E+5
1E+6
1E+7
1E+8
0 50 100 150 200
Temperature (°C)
Complexviscosity(Pa.s)
A
B
C
F
E
D

Comparison DSC analysis & rheology
1E+2
1E+3
1E+4
1E+5
1E+6
1E+7
1E+8
-50 0 50 100 150 200
Temperature (°C)
-0,3
-0,2
-0,1
0
0,1
0,2
0,3
Heatflow(W.g
-1
)
Tg
DA

Application area corrosion protective powder coatings
High T
High T
N
O
O
O
Powder on aluminium Cross linked coating upon cooling
Marked with large scratch Cross linked coating with closed scratch
n m
CH2 C CH2 C
CO
CH3 CH3
CO
O
C4H9
O
CH2
n m
CH2 C CH2 C
CH3
CO CH3
CO
O
C4H9
O

Thermoreversible behaviour of the Diels-Alder system can be shown by means of
rheological measurements: no deterioration of behaviour upon repetitive heating-cooling
steps; test have been performed for at least 5 cycles …
1E+2
1E+3
1E+4
1E+5
1E+6
1E+7
1E+8
0 60 120 180
time (min)
25
75
125
175
Temperature(°C)

Addition of pigment affects thermo-rheological behaviour
1E+2
1E+3
1E+4
1E+5
1E+6
1E+7
1E+8
0 50 100 150 200
Temperature (°C)

Material Synthesis:
TNO
Suprapolix
L’Urederra
Characterization:
University of Patras
University of Ioanina
www.Hipocrates-project.eu
Start: 2013 Nov
End: 2016 Nov
Total budget: 2,8M€
TNO budget: 250k€
Composites and
Mechanics:
University of
Bristol
Element
GMI
Application:
Inasco (database)
Aernova (planes)
Project Management:
Tecnalia

TNO approach
Combine mechanical properties of
highly crosslinked thermosetting
polymers…
… with thermo-reversible behavior
/processability of thermoplastic
systems …
… for fabrication of self-healing
fibre reinforced composites for
aerospace applications
Epoxy Chemistry
Diels-Alder Chemistry

Schematic overview of the process
Multifunctional
Monomers
Thermoset-like
Polymer
Thermoplastic-like
Polymer
Healed
Damaged
Key challenges:
Side-reactions
Viscosity
Compatibility / Stoichiometry
Curing / healing conditions
Including fibres
Heating

Varying the Crosslink density
Crosslink density depends on
Maleimide to Furfuryl ratio, r
r = 1
highest crosslink density
r = 2, no crosslinks due to
oversaturation
Effective chain length increases
Crosslinks start to form
Less groups available for
crosslinking
# crosslink donors (X)
# crosslink acceptors (O)
r =
Concentration of crosslinker expressed in r
r = 0 r = 0,5 r = 1 r = 1,5 r = 2

Crosslink density – Solvent Swelling
The mass of a piece of polymer is determined before and after submersion in
dichloromethane for one day
Uncrosslinked material is dissolved in CHCl2, ∆m < 0
Loosely crosslinked material, flexibility to expand and absorb solvent voids, ∆m>0
Highly crosslinked material, dense and rigid, no room for solvent, ∆m = 0

Crosslink density – Rheology
Increase of concentration of
cross-linker:
Increase viscosity of liquid
state
Plateau of solid state is
broadened but remains at
the same height (mechanical)
Does not affect side-reaction
Prepolymer only does not have a
solid state plateau

Resin Mechanics
Test series #1
Material too strong for testing!
Self-healing material remains
Embedding host epoxy fails instead
Test series #2
As strong as benchmark
Successful multiple (3) self-healing events
Self-healing efficiency ~100%

N
O
O
O
R 1
R
R 2
O
O
O
N
Solid
Liquid
Additive to introduce self-healing
Can be incorporated in “traditional” paints
Combined with novel resins (e.g. ionomers) to
enable thermoplast behaviour
>T
<T
Synthesis of additive

Results - rheology
Temperature
cycle
Viscosity
response
Coating without
additive
Diels- Alder
additive
Modified coating

Coating without
additive
Additive
Increasing
additive amount

Reversibele Crosslinking - Applications
• SH COATINGS
• Recycling of plastics
• Encapsulants which open at elevated temperatures
• Changes in solubility/viscosity at high temperatures, sensorics,
• Thermally removable adhesives
• Reversible data storage medium…
• …

Patents within TNO regarding DA-chemistry
US patent No. 9,051,480: Temporary functional finishes for textile applications, Principle:
using reversible DA to attach functionalities to surfaces with the option to change surface
character and/or to restore surface functionality
WO 2012044160 A1: An active carrier for carrying a wafer and method for release based
on DA Chemistry
WO 2010044661 A1: Recycling an organic-matrix composite material; binder of composite
with reversible x-links based on DA-chemistry
WO 2004076567 A1: Low solvent coating process for applying the coating to an object
coated object obtainable with the process and process for levelling a coating applied to an
object

Shared Research: How does it work?
Jan Willem Slijkoord
:

Contents
J.W. Slijkoord/Sander Gielen dd. May 20th
2015
Shared Research participation fee and entrance fee
IP model, IP ownership & User rights
Steering Group Meeting procedure
Confidentiality

Why this self-healing shared research program?
2015
• Development approach of shared research programs characterized by the
• Development of generic technology requiered for all participants
• Development of company specified self-healing demonstrators
• Reduced R&D risks:
• by group of participants rather than by one company only
• Accelerated innovation by agile shared research approach
• Parallel program work packages
• Application foreground IP by participants active in the coatings value chain

TNO has long-term track record in shared research programs
2015
Holst Center: Shared Research in flexible electronics
Since 2005
38 industrial companies
Joint Industrial Program “Sustainable Chemical Product Performance”
Project since 2015
Joint Industrial Program “Stress Relaxation Cracking”
Project since 2013

27-7-2015
Some of our Industrial Partners…

Shared Research Participation & Entrance Fee (1/2)
TNO & company
background R&D and IP
Self Healing Additives
Shared Research Program
Company Y
Participation fee +
(optional) entrance fee
Start End
Company X
Participation fee

Shared Research Participation & Entrance Fee (2/2)
TNO & company
background R&D and IP
Self Healing Additives
Shared Research Program
Company Y
Participation fee +
(optional) entrance fee
Company X
Participation fee
• Indication participation fee per participant: 25 kEUR.
• Final participation fee can be lower or higher, dependent on desired:
• IP Domain range wide or limited
• Voting rights
• More or less demonstrators to be delivered
• In case participants will join the program, TNO will actively seek
precompetitive financial leverage of the project

IP model for Shared Innovation
2015
Shared

IP Ownership & User rights in the self healing program
2015
• TNO will be owner of foreground IP in Self Healing Additives Research Program
• All participants will get an non-exclusive user right within the agreed application domain

The steering group meetings during the program:
Role & Responsibility (1/2)
Role Steering Group = monitor results & influence program
• Steering group is decision making entity.
• It evaluates intermediate results & makes decisions about the future R&D activities in
the program and other relevant decisions, such as:
Changes to original research plan and suggestions for successive research
Publication of (intermediate/final) reports
Specification of demonstrators
Entry of new participants
2015

The steering group meetings during the program:
Role & Responsibility (2/2)
Main responsibilities of the steering group:
- Guide the development for self healing additives
- Evaluate interim and final results of the research programme
- Agree on the research programme activities for the next 6 months
2015

Voting & decision making during steering group meetings
Voting
Each participant has one vote, irrespective of the number of representatives
Decisions shall be taken with at least two-thirds of the votes
TNO scientifically responsible chair
TNO is chairman of the steering group meetings
TNO will prepare decisions to be taken, so has NO vote.
TNO is NOT a program participant but the scientifically responsible chair
SCPP kick-off meeting

Public
Confidentiality
TNO will
Not reveal or publish member’s confidential information, without its prior
written approval
Reveal or publish any results only with approval of the steering group
Participants
Any objection of publication or other release of IP is justified if the
protection of the member’s confidential information is adversely affected
SCPP kick-off meeting
Steering group
TNO – Cie
1-1
confidentiality

47
Further questions about participation & commercial issues?
Please Contact:
Mr. J.W. Slijkoord MSc.
Business Development Mgr
Mail: jan_willem.slijkoord@tno.nl
Phone: +31 (0)6 51 81 34 93

Summary: Project set up
Corné Rentrop
:

Project set-up
Phasing:
TNO foresees 4 phases for Self-healing coatings based on Diels Alder
technology.
1) Coating systems identification and design of DA Additive
2) Synthesis of DA additive
3) Introduction DA additive into coating systems and coatings
evaluation
4) Upscaling of the DA additive to pilot scale

Phase 1: Coating systems identification and
design of DA Additive
Activity:
Every participating coating manufacturer has the opportunity to
define a coating chemistry (epoxy, alkyd, polyurethane, … ) for
possible addition of the DA additive.
In close cooperation with the coating manufacturers and chemical
suppliers a suitable design for the DA additive will be made.
The design will be based on the targeted flexibility and
compatibility with the coating system, the state of the art cross-
linking chemistry in the formulation, and the targeted de-coupling
temperature depending on the coating application.

Phase 1: Coating systems identification and
design of DA Additive
Result:
Theoretical design of DA additives for each coating manufacturer/
and coating system
Additive that is producible by chemical companies
Mutual meeting with all partners sharing results.

Phase 2: Synthesis of the DA Additive.
Activity
Each DA additive as proposed in Phase 1 will be synthesized.
A first order compatibility study will be executed with the targeted
coating system
Characterisation of the Diels Alder additive
E.g. indication of the de-coupling temperature and self-healing
characteristics.
Optimising the Diels Alder additive design

Phase 2: Synthesis of the DA Additive.
Result:
Small scale samples of the DA additive for evaluation purpose at
TNO
Model coatings including the Diels Alder additive.
Report describing the synthesis of the Diels Alder additive and a first
order evaluation of the self-healing characteristics of the resulted
coatings
Mutual meeting with all partners sharing results.

Phase 3: Introduction of the DA Additive into the
coating systems and coatings evaluation
Activity
The best performing DA additives from phase 2 are synthesised on a
larger scale.
The DA additive is distributed to the coating manufacturers.
Coatings are formulated at the manufacturers laboratories using a
model recipe.
Coating manufacturers will optimise performance (loading,
crosslinking, resin).
Pigmentation and other coating formulations is also done at the
coatings manufacturers to study the effect of these ingredients on
ultimate performance.
Evaluation is focussed on the targeted self-healing properties and
typical coating properties (thickness, adhesion, UV stability).

Phase 3: Introduction of the DA Additive into the
coating systems and coatings evaluation
Results:
DA additives on a larger scale
First order recipe to create the self-healing coatings
Self healing coatings created by the coatings manufacturers
Evaluation report of the coatings
Mutual meeting with all partners sharing results

Phase 4: Upscaling of the DA additive to pilot
scale (Designed for Chemical suppliers).
Activity
The recipe of a suitable DA Additive (results of phase 1 and 2) is
supplied to an additive manufacturer
The manufacturer produces the additive on a larger scale.
Materials is supplied to phase 3
Iterations on DA additive

Phase 4: Upscaling of the DA additive to pilot
scale (Designed for Chemical suppliers).
Results:
Demonstration of a DA additive available on pilotscale (e.g. kg scale)
Evaluation report of the DA additive
Mutual meeting with all partners sharing results

Project phasing
Set of demands:
• Clustering
• Additive design
Synthesis of DA additive
Introduction in coatings
systems
Upscaling of
Diels Alder
additive
1 year Evaluation

no. Participant Country Organisation Type
1. Rapra UK LE
2 Fraunhofer ICT D RTD
3 TNO NL RTD
4 EDAG D LE
5 Archimedes Polymer CY SME
6 PPG NL LE
7 Norner AS N SME
8 Comfil ApS DK SME
9 Loiretech SAS F SME
10 Coriolis Composites SAS F SME
11 NEN NEderlandse Norm NL Association NEN

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