Ultra Violet (UV)/ Electron Beam (EB) Curing of Coatings: Operation - Applications - Market

Baskar Vairamohan
Project Manager
Industrial Center of Excellence Webcast
September 18, 2014
Ultra Violet (UV)/ Electron Beam (EB)
Curing of Coatings
Operation – Applications – Market

2© 2014 Electric Power Research Institute, Inc. All rights reserved.
Contents
•EPRI - Introduction
•UV/ EB Operation - Basics
•Applications
•Market Survey
•RadTech 2014 Conference – Round up
•Vendor Contacts
•Additional Resources

About EPRI
• Founded in 1972 as an independent,
non-profit center for public interest
energy and environmental research
EPRI’s Mission
Advancing safe, reliable, affordable
and environmentally responsible
electricity for society through global
collaboration, thought leadership and
science & technology innovation

Our Members…
• 450+ participants in more than 30
countries
• EPRI members generate
approximately 90% of the electricity
in the United States
• International funding of nearly 25%
of EPRI’s research, development
and demonstrations

Independent
Collaborative
Nonprofit
Three Key Aspects of EPRI
Independent
Objective, scientifically based
results address reliability,
efficiency, affordability, health,
safety and the environment
Nonprofit
Chartered to serve the public
benefit
Collaborative
Bring together scientists,
engineers, academic
researchers, industry experts

Natural Source of UV Light
• Ultraviolet (UV) light has shorter
wavelengths than visible light.
• The Sun is a source of the full
spectrum of ultraviolet radiation,
which is commonly subdivided
into UV-A, UV-B, and UV-C.
• Some insects like bumble bee
can see this UV light

UV Basics
• Using UV energy (photons),
visible light to form a coating,
film or ink.
• Replaces thermal, evaporative,
or oxidative (air-dry) curing
• UV/ EB Types:
– Ultra Violet (UV): 100-400 nm
• UV-A: 315-400 nm (Long)
• UV-B: 280-315 nm (Medium)
• UV-C: 100-280 nm (Short)
– Electron beam: high energy
electrons

UV Basics (Contd…)
• UV radiation is emitted by, and
absorbed by, the valence electrons
of atoms.
• When an electron in an outer atomic
orbital encounters a photon with the
right level of energy, the electron will
absorb the photon and move from
its normal “relaxed” state to an
“excited” state.
• If the photon has enough energy,
the electron will leave the atom
entirely and become a free electron,
or free radical.
• Sources for UV:
– Most common is medium-
pressure (MP) mercury vapor
lamp.
– An electrode arc or
microwave energy is used to
excite the mercury, which
causes the UV emission.
– UV Light Emitting Diode (LED
is an emerging technology)

What is Curing?
• Curing is a set of chemical and physical processes that
coating materials must undergo after drying.
• The coating must attach itself to the substrate physically
(adhesion) or chemically (cohesion) and must cohere to
itself.
• It also need to undergo chemical reactions such as
“polymerization” (formation of plastic). These processes are
known collectively as curing.
• Depending upon the chemistry of the coating material,
curing can take place at room temperature, at elevated
temperatures, or by free radical reaction (UV/EB).

What is Curing? (Contd…)
• Non-UV Curing Process:
– Two Step Process:
• First Step – Solvent based paint is dried to remove
moisture
• Second Step – Thermal curing of the coating so the
coating adheres to the surface.
– Most of the industrial coatings used today are thermally
cured
– With thermally curable coatings, adding heat can
accelerate the curing process, but care has to be taken
not to overheat the coating.

Requirements of UV/EB Curing
Application
Energy
Source
(UV/EB)
Formulation
These 3 elements have to
work together to get
correct coating properties

Formulating a UV Curable System
PI*
Additives
Monomers
Oligomer
• Photoinitiator (Free-radical) : Any
chemical compound that
decomposes into free radicals when
exposed to UV
• Additives (Performance Tuning):
Chemical agents such as pigments,
fillers, wetting agents, etc. that add
various properties to the coating.
• Monomer (Viscosity and
Flexibility): A molecule that may
bind chemically to other molecules
to form a polymer.
• Oligomer (Basic Coating
Properties) : A polymer or polymer
intermediate or resin containing
relatively few structural units.
* PI stands for Photo Initiator

Role of Photo Initiators (PI)
• They absorb UV light or electrons to
form free-radical
• They initiate the polymerization process
by adding themselves to monomer/
oligomer
• Different PI’s absorb UV at different
wavelength
• The wavelength of PI should be
matched with wavelength of UV lamp
for optimal results
• They only react with UV to Visual light
in the electromagnetic spectrum
• They have long shelf life
Source: http://www.esf.edu/outreach/uvebwebinar/documents/Intro_Basic_UV_curing2012_MJI.pdf
Image Source: http://www.gallus-group.com/desktopdefault.aspx/tabid-
370/569_read-1681/

UV Curing Process
• UV curable coatings contain a
catalyst called a photo-initiator.
• Photo-initiators generally react to
wavelengths of between 200 and
400 nm.
• They absorb UV light and starts
a photochemical reaction that
employs the use of free
electrons, or free radicals, and
causes an almost instantaneous
cross-linking of the resins.
• UV curable coatings are
formulated with unsaturated
resins that are capable of free
radical reaction.
Photo Source: Lumen Dynamics
http://www.ldgi.com/technology-learning-center/uv-bonding-curing/curing-process/

UV Curing Process (Contd…)
• Unsaturated resins have fewer hydrogen atoms or
equivalent groups than saturated resins and will combine
directly with hydrogen, chlorine, oxygen, or various other
substances to form long chain polymers.
• Only the photo-initiator and exposure to ultraviolet light are
required to start and complete the reaction.
• Thermal processing is not necessary to cross-link the
resins used in liquid UV-curable coatings.
• Note: Some heat may be necessary with UV-curable
powder coatings in order to melt, flow, and level the
particles of powder before curing.

Electron Beam Curing
• Uses electrons to complete the
polymerization process
– Electrons open double bonds
initiating polymerization
– Note: no photoinitiator required
• EB systems can use UV formulations
to get the required properties (opposite
case is not true)
– Electrons decompose photoinitiator
to form acid which then initiates
polymerization
• EB systems formulations are less
expensive than UV system
formulations because of the absence
of photoinitiators
Additives
Monomers
Oligomer
EB Formulation

Electron Beam Properties
• Ionizing radiation (low energy
electrons):
– Sufficient energy to break
bonds in coating to generate
free radicals
– Can penetrate into and
through a coating/ink and
through substrates
– Generate little or no heat
– Precision controlled
– Not affected by pigmentations
or transparency of coating or
substrate

Scratch Resistant Tests for UV/EB Coatings
• Steel Wool Tests
• Pencil Hardness Test
• Taber Wear Test
• Scratch measured in microns
Source: http://www.pcoatingsintl.com/wp-content/uploads/2014/04/A-Critical-Study-On-Scratch-Resistance-Tests-C-George-
Drazinakis.pdf
Rotary Steel Wool Tester
Pencil Hardness Tester
Taber Wear Tester (Haze Value)

Additive Manufacturing – 3D Printing
Digital to Physical
3D CAD File Printing ResultPrint the model
Courtesy : Stratasys
Traditional Manufacturing – Subtractive
Digital Manufacturing – Additive (Building Layer by Layer)

Technology – PolyJet Process
Courtesy : Stratasys

New and Emerging Applications
• Bio-inspired Glue – Medical Field
• Shark Skin Aircraft Coatings
• Ultra-thin PV Application
• UV for rail road repair

Applications of UV/ EB Curable Coatings
• Industrial coatings and graphic arts
market segments:
– Coatings for wood furniture and
flooring
– Coatings for plastic, metal and
paper
– Fiber optic coatings
– Coatings for electronic
components
– Coatings used on automotive
components
– Overprint varnishes
– Flexographic inks
– Screen Print inks
– Lithographic inks
– Laminating and pressure
sensitive adhesives

Roll-to-Roll Coating Applications
• Other Applications;
– Display and Touch
Screens
– Solar, Battery and Fuel
Cell
– Flexible Electronics
– Medical
– Membranes
– Aerospace and
Automotive
– Lighting
– Many more….
Source: Carestream Tollcoating

Advantages of UV Curing
1. Much faster than thermal processes - UV coatings cure in
a matter of seconds, rather than minutes or hours.
2. Faster start-ups and shut-downs and lower energy
consumption - UV lamps turn on and off almost
instantaneously. There is virtually no energy or time lost
waiting for the oven to come up to temperature in order to
start or resume production, and stand-by modes are not
necessary.
3. Improved productivity - Because UV coatings cure in a
matter of seconds, higher line speeds are possible.
4. Less contamination – lower reject rates - No air
movement to exhaust byproducts of combustion is
necessary in UV curing systems. This reduces the
chance of air-borne contamination of the coating.

Advantages of UV Curing (Contd…)
5. Reduces or eliminates VOC emissions and solid waste
disposal - Many UV coatings are 100% solids and contain
no solvents; thus VOC emissions can be eliminated.
6. Less space required - Due to the speed of cure, UV
systems require less floor space.
7. Superior finishes - UV curable coatings can offer improved
performance and visual properties.
8. Less thermal, noise, and air pollution - less thermal
pollution of the workplace and less noise pollution from
fans, burner regulators, etc. due to low heat requirement.
9. Can be used on temperature-sensitive substrates -
Substrates such as wood and plastic, and fully assembled
products that may contain gaskets and/or fluids, can be
safely coated with UV curable coatings.

Drawbacks of UV/EB
• Additional capital cost
– retrofitting can sometimes be difficult
– EB systems are expensive (capital cost), but is cost
competitive for many applications
• Inks and coatings are can be more expensive per pound
– but offset by improvements in productivity, superior
appearance
• Re-training of operators
– UV/EB inks/coatings perform differently compared to
conventional inks and coatings

UV/ EB Formulated Average Annual Growth
Rate since 2011 (by Volume)
Source: RadTech 2014
27%
15%
15%
14%
14%
9%
8%
8%
8%
6%
0% 5% 10% 15% 20% 25% 30%
3D PRINTING/ ADDITIVE MANUFACTURING
MEDICAL APPARATUS
GRAHIC ARTS - INKJET INKS
DENTAL APPLICATIONS
OPTICAL ADHESIVES
METAL DECORATING
PRINTING PLATES
ELECTRONIC ADHASIVES
OPTICAL FIBER
FLOORING

2013 Worldwide Raw Materials Use for UV/EB
Curing (Total = 489,000 MT)
Oligomers
39%
Monomers
49%
Photoinitiators
10%
Pigments/ Additives
2%
Other
12%
Note: MT – Metric Ton (= 1000kg = 2205 lb)

Worldwide & Europe UV/ EB Curing
Applications
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
World Europe
Worldwide Raw Materials = 489,000 MT
Europe Raw Materials = 150,000 MT

Sales of UV Lamp Technology – New Trend
$45
$269
$309
$507
2012 2023
UV LED Lamps Traditional UV Lamps
Sales in millions of US Dollars

Markets for UV Applications
Source: EPRI

RadTech 2014 Conference
May 12-14, 2014
Chicago, IL

RadTech International (North America)
• RadTech is a non-profit trade association
• Over 700 Members
• Active for almost 30 years
• Our members are across the supply change
• Members support over 20 application areas for UV and EB
• Link: www.radtech.org
• Contact Information:
Gary M. Cohen | Executive Director
Phone: 240.497.1242 | Email: gary@radtech.org
Mickey Fortune
Phone: 240.643.0517 | Email: mickey@radtech.org
Address:
7720 Wisconsin Avenue, Suite 208
Bethesda, MD 20814

Vendor Contacts from RadTech 2014
EB VendorsUV Vendors

Phoseon Technology

Nordson Corporation

Toll Coating

Heraeus

Miltec UV

Energy Science Inc. (ESI) – UV and EB

Philips Lumileds
5x96 = 480 LED’s in this strip
– each with individual control

American Ultraviolet

Jelight Company, Inc.

PCT Engineering Systems – EB Curing

Bayer

Examples of UV/ EB Curing

Other Resources
1. UV Curable Coatings -- Marketing Kit – EPRI Product (1000138)
– 2000 (Free-of-charge Download)
http://www.epri.com/abstracts/Pages/ProductAbstract.aspx?Prod
uctId=000000000001000138
2. UV & EB Curing of Coatings - Power of Light, Dr. Mike J.
Idacavage (PL Industries A division of Esstech, Inc.), RadTech
UV & EB 2014, May 12,13 2014
3. RadTech – Trade Association for all UV/EB curings- Formulations
and Equipment – www.radtech.org
4. Proceedings from RadTech 2014 is available at
http://radtech.org/2014proceedings/
5. CEATI – Electrotechnologies –Energy Efficiency Reference
Guide:
http://www.ceati.com/freepublications/7020_guide_web.pdf

Questions

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Ultra Violet (UV)/ Electron Beam (EB) Curing of Coatings: Operation - Applications - Market

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