ABRAFATI 2015 OVERVIEW OF LOW ENERGY EB FOR INDUSTRIAL COATINGS 100915

“OVERVIEW OF LOW ENERGY ELECTRON BEAM TECHNOLOGY
FOR CURING OF INDUSTRIAL COATINGS”
By Anthony Carignano
PCT Engineered Systems, LLC
1
INTRODUCTION
Over the past decade the commercial use of low energy electron beam (EB) technology
has significantly increased in a variety of industrial applications. Electron beam equipment
design advancements have resulted in safe, consistent and reliable process methods for a
broad range of surface curing and polymer crosslinking applications. Numerous value chain co-
suppliers have stepped forward with complimentary EB curable coatings and process
additives. Miniaturized, economical sealed electron beam lamp (ebeam Lamp) technology,
originally designed for surface sterilization applications, has equally opened the scope and
integration possibilities of low energy EB into multiple new surface curing applications areas.
This paper and presentation will focus on the development of low energy EB equipment
and processes as a new way of curing various industrial coating systems. Applications covered
in the presentation will include coil and sheet applications for non-food general line metal
packaging. A case study on the successful incorporation of EB curing on an industry metal
packaging line will be reviewed. EB process benefits from minimized energy consumption to the
ability to instantaneously cure high solid systems will be covered. Outside of metal coatings the
presentation will cover emerging areas of EB for curing on three-dimensional objects.
WHAT IS COIL COATING?
Coil coating, also known as "pre-painted metal coating," is an automated inline process
that involves roll coating coils of flat metal. After coating the metal substrates (generally steel
and aluminum) are put through a forming process that bends and draws the coated metal into
intended end-use shapes with little or no cured imperfections such as film cracking, crazing or
delamination. Over 70% of coil coatings are typically formulated for high performance
applications. Weathering, corrosion resistance and longevity of aesthetics are all highly desired
key attributes. In addition, metal substrates converted with conventional coil coating systems
require chemical pretreatment and must be preheated to a target activation temperature before
organic solvent based coatings can be applied. Typical conventional coil coating processes
require the use of over 100 foot long drying ovens with solvent incinerators and explosion proof,
ventilated coating rooms. At the end of the process a quenching (cooling) zone is required to
reduce metal

2
temperature before additional coating layers can be applied prior to rewinding. In addition, large
and costly accumulators are required to keep lines moving during coil changes.
Source: National Coil Coating Association https://www.coilcoating.org/how-to-paint-metal-coils
Coil coating lines are built for long runs to reduce overall operating costs. Aside from
applications in general infrastructure, transportation and consumer appliance industry
applications, coil coatings are now finding use in “smart applications” that fulfill requirements
from promoting smog protection and antimicrobial properties to optimizing HVAC heat exchange
in commercial buildings. According to a recent market report published by Research and
Markets: “it is anticipated that the global market for coil coatings will grow at a CAGR of 6.5%
from 2014-2019.” Key global suppliers of conventional coil coatings systems include Akzo
Nobel, BASF, PPG and Valspar. Key drivers for the adoption of coil coated products include
performance, cost reduction and sustainability.
WHAT IS ULTRAVIOLET (UV) AND LOW ENERGY ELECTRON BEAM (EB) CURING
TECHONLOGY?
Ultraviolet curing (commonly known as UV curing) is a photochemical process in which
high-intensity ultraviolet light is used to instantly cure or “dry” inks, coatings or adhesives.
Contrary to free-radical UV curing which requires photoinitiators (or at least some photo-reactive
moiety incorporated into an oligomer backbone) for polymerization, low energy EB (which is
defined as operating with an accelerating voltage of less than 300 kV) accelerates electrons
produced by EB equipment with sufficient energy to break chemical bonds within coatings

3
without need for photoinitiators. It is the bond breaking (scission) induced by photointitiators in
UV curing and with electrons in EB curing which generates free radicals and initiate the
polymerization (crosslinking and curing) of coating films. One major advantage of EB curing
over UV curing is that EB provides the ability to cure high opacity, high film build coating
systems at near room temperature without photoinitiator.
SOURCE: ADAPTED FROM AMERICAN HERITAGE ENCYCLOPEDIA
Compared with conventional drying and curing methods, EB curing requires less footprint and
drastically reduces the elapsed full cure time for coatings from minutes to a fraction of a second. It
eliminates the need for large thermal drying ovens, cooling lines, solvent incinerators or explosion
proof rooms. “Comparing basic information on the evaporation and drying of solvents and
diluents, like water, versus EB curing, one finds a remarkable savings in the energy merely
required to dry or cure a coating.”…” EB curing is a direct means of energy transfer. Energy
emitted from an EB unit is directly absorbed in the coating and causes the chemical changes
that convert a liquid coating into a dried and cured material. Drying and curing take place
irrespective of pigment type or total pigment volume content loading.”i
In addition, Lapin and
Minon concluded in 2008 that: “total energy costs for conventional thermally cured coatings are
between seven and nine times higher than for a UV/EB cured coating system, putting
conventional energy consumption in the range of 4,600 to 5,900 Btu/m2.” Calculations
Adapted from American Heritage Dictionary

4
completed by Lapin and Minon are similar in magnitude to savings calculated by Coors1
and
BASF in earlier energy studies on the energy savings benefits of energy curing technology.”ii
CONSIDERING EB CURING TECHNOLOGY IN INDUSTRIAL COATING APPLICATIONS
COIL COATING
The chemistries used in conventional coil coating systems are almost universally organic
solvent based and include epoxies, acrylics, polyurethanes, fluorocarbons, plastisols and
polyesters. Siliconized polyesters, durable polyesters and poly(vinylidene)difluoride (PVdF)
systems are used almost exclusively for exterior construction applications. PVdF and siliconized
polyesters coatings have excellent weathering characteristics which allow manufacturers to
promote 40 year performance warranties. Plastisol coatings based on poly (vinyl) chloride, offer
excellent forming, mar and chemical resistance characteristics and are principally used in heavy
duty construction applications for chemical plants, smelting operations and in agriculture.
Conventional waterborne coil coatings serve niche applications and require greater energy to
drive off the water and cure than solvent based systems.
Most resin backbone chemistries used in conventional coil coatings have similar acrylate
functional types used in photo polymeric surface curing. PVdF has been known to be cross-
linkable with low energy electron beam and is one well known resin binder currently being
investigated in the manufacture of novel lithium ion battery storage devices. Acrylate functional
polyester resins have been commercially available for decades. Less common coil coating
chemistries including epoxies (used mainly in primers), acrylics (used for transportation and
building applications) and urethanes (used in primers) all have acrylate functional analogues
adapted for direct to metal applications. A growing number of global conventional coil coating
suppliers and certain regional specialty coating manufacturers in the Americas now offer
acrylate functional systems specifically designed for UV/EB coil coating applications. In
addition, more than a dozen highly competitive acrylate functional resin suppliers now offer
monomer and oligomer species specifically designed for metal coatings.2
1
Coors Brewing Company adopted ultraviolet (UV) light curing technology for aluminum beverage cans in
the late 1990s. BASF is a global manufacturer of specialty chemicals and intermediates.
2
Leading global acrylate resin suppliers include: Sartomer, Allnex, Basf, Miwon, Eternal, AGI, IGM and Rahn.

5
The use of UV/EB 100% solid energy curable surface curing in metal coil coating
operations can be traced back to British Steel (U.K.) and Nisshin Steel (Japan) in the early
1990s. Since then, barriers to the large scale commercial adoption of UV/EB curing for coil
coatings applications have significantly diminished. Raw material costs have become much
more affordable as acrylate functional monomers and oligomers have commoditized.
Technological advancements made in acrylate functional polymer chemistry have significantly
improved coating performance relating to flexibility, impact resistance, weathering
characteristics and tenacious film adhesion which is required in most all metal coil applications.
Still there are very few commercially formulated EB coil coatings qualified to replace
conventional coil coatings. Significant development is required.
HYBRID UV/EB COIL COATING LINE DESIGNiii
Source: “UV/EB Technology for Coil Coating” Presentation RadTech UV/EB West 2013
A CASE STUDY EXAMPLE OF UV/EB COIL COATING IN COMMERCIALIZATIONiv
Cleveland Steel Container (CSC), the largest steel pail producer in North America,
designs and manufactures steel pails for industrial and consumer product applications and is. Its
parts manufacturing plant in Streetsboro, Ohio, makes covers, bottoms and tops for all CSC pail
plants in the United States. In March 2012, CSC decided to implement a new, centralized coil
coating and press line in Streetsboro to make pail lids for all operations. In lieu of employing
thermal drying technology for its new line, CSC chose ultraviolet (UV) and EB hybrid curing. The
steel pails converted as a result of this process are composed of three parts: a body, the bottom
ELECTRON
BEAM
CLEANING
BACKER
APPLICATION
REWIND
UNWIND
PRIMER
APPLICATION
TOP COAT
UV GLOSS
CONTROL
TOP COAT
APPLICATIONPRIMER
UV CURE
BACKER
UV CURE

6
and the top (or lid). The new hybrid EB/UV Streetsboro coil line process, coils are unwound and
flame-treated to enable optimal coating adhesion. The top and bottom sides of the coil are first
roll coated. A highly pigmented urethane acrylate functional system is applied to the top side of
the coil which will eventually be shaped and crimped into a lid. The bottom side of the coil (the
inner lid) receives a clear UV coating. At a line speed of over 300 feet per minute the bottom
side of the coil is cured first with UV lamps. The top side of the coil is then cured at a dosage of
4-12 Mrad. The coated coil goes in front of the EB at an ambient temperature of circa 100F. Due
to thermal absorption of the metal coil, the EB cured top side of the coil emerges at
approximately 150F. Flame treated, uncoated coil is somewhat porous and CSC believes that
substrate porosity and inline process heat transferred into the coil actually allow for better flow
and substrate hinging of the acrylate functional chemistry immediately prior to the UV/EB
crosslinking process. Compared to the conventional coating chemistry used in the past, CSC
also found that EB cured coatings actually exhibit much lower delamination and cracking in
crimped areas of the outer pail lid.
From proof of concept to installation, CSC’s new line was completed in eighteen months.
CSC worked with Watson-Standard (W-S) to formulate its UV/EB coating. CSC found other EB
curing benefits beyond energy costs savings: no loss of evaporated solvent, in-can stability over
time and much less clean up as UV/EB coatings are easier to clean than solvent systems which
can harden on the coating line. As UV/EB systems are non-flammable and high solids, up to
100%, UV/EB curing also uses less applied coating and storage area. Overall, after doing the
math and achieving six fold line speed increases using its hybrid UV/EB coil coating line, CSC
believes that UV/EB systems are competitive in total cost of ownership when compared with
conventional solvent based coating systems.

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CHALLENGES FOR THE INTRODUCTION OF UV/EB IN COIL COATING APPLICATIONS
There are significant performance and cost barriers to using current UV/EB coating
system based on polyester and aliphatic urethane chemistry that will make it difficult to match
the weathering and durability performance found in siliconized polyester/melamine or PVdF
based systems. For example, Cymel 303, a highly methylated melamine resin and Resimene
747 hexamethoxymethyl melamine-formaldehyde are two well know resin system ingredients
commonly used in conventional weather resistant coil coating applications. Both sell for
approximately US $2/kg. While some low-end acrylated monomers may be in the price range,
Left: EB cured highly pigmented coil coatings in
black, gray and white supplied by Watson-Standard.
Left: UV cured clear lacquer used for pail interior
supplied by Watson-Standard.
Left: Crimped, crotch area of outer pail. Coating exhibits
excellent resistance to delamination or cracking.

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other high performance aliphatic urethane acrylates which are better in overall weathering
properties and provide abrasion resistance and adhesion are typically above US$6/Kg.
Another UV/EB coil coating market adoption challenge is end user awareness.
Producers of metal coil are faced with two sets of customers: the coaters who paint the metal
and the OEMs who fabricate the final articles and bring them to market. The needs of these two
sets of customers differ and sometimes even conflict depending on geographic. In general,
fabricators are most concerned about performance attributes. Coaters have no influence over
coatings used but still attempt to exert influence over OEMs who fabricate through pricing
strategies. In North America, suppliers of conventional coil coatings have limited motivation to
develop disruptive technologies unless compelled to do so by brandowners. Although there has
been much discussion over the past decade regarding UV/EB energy curable coil coating
technology, it is most likely that companies interested in bringing their own coil coating process
in house along with end users in Europe and Asia Pacific concerned with lowering overall VOCs
and energy costs are best fit candidates for adoption.
EB FOR INDUSTRIAL COATING BATCH PROCESS APPLICATIONS
Over the past decade, EB surface curing technology has gradually been adopted in a
variety of batch coating and printing applications. Its ability to cure and crosslink through highly
filled opaque and metallic pigmented film surfaces without the effects of shadowing are
desirable for profiled and multidimensional shapes. The photo below shows coated 3D parts
immediately following ebeam surface curing. The surface cured 3D parts were irradiated with a
COMET 200kV EBLab Unit at a dosage of 3MRad while travelling at 30 meters per minute. The
EBLab uses integrated sealed ebeam 400mm Lamp.
Shielding and throughput are two major considerations when integrating low energy
ebeam Lamps into surface curing applications. These considerations become more complex
when going from continuous inline processes to smaller footprint multidimensional surface

9
Photo: Surface curing 3D parts inside of lead shielded 200kV ebeam
Technologies EBLab nitrogen inerted chamber.
curing applications. “When an accelerated electron impinges upon any material, it generates X-
radiation or X-rays. As a result, shielding is needed to prevent exposure to X-radiation.”v
For low
energy ebeam Lamp integrated equipment (at or below 300 kV), shielding is accomplished
through multilayered steel and lead constructions. As a part of the ebeam equipment integration
processes, shielding design labyrinths are developed where all x-ray escape points are
addressed.
Throughput is a measure of EB energy deposition rate and relates directly to the amount
of material or parts that can be surface cured or crosslinked within a given time and rate of
speed. Throughput is measured in MegaRad (MRad) or kilogray (kGy) meters per minute. One
kGy is equal to one joule per gram of absorbed energy per mass and 10 kGy is equal to 1
MRad. Since electrons have mass and electrical charge, their penetration into materials is
limited by their kinetic energy, distance from target and by the mass and density of the target
substrate. Depending on throughput and coating density requirements, typical values of the
dose needed for coating drying and curing applications can range anywhere from 15-30 kGy.
The photo (below) shows an ebeam integrated 3D 100kV curing system for 63.5mm x
270mm shapes. The system has a maximum duty of circa 480 parts per minute which can be
robotically fed onto a rotating mandrel index system. Aside from surface curing, the system is
integratable with spray and digital inkjet printing functions. The system has also been

10
considered for applying and crosslinking adhesives on cylindrical objects.
Photo: 3D ebeam curing system.
EB INDUSTRIAL COATINGS: THE ROAD AHEAD
Although EB surface curing technology is now nearing its 50th
anniversary of commercial
use in industrial coating applications, the arrival of ebeam Lamp technology for inline smaller
footprint applications is a potential game changer for the technology and emerging applications.
In general, the adoption of EB as a preferred method for surface curing industrial coatings
provides energy and labor savings, reduced environmental risk, consistent cure performance
and outstanding end product wear resistance. The shift towards lower VOC coatings and a
carbon taxation driven by schemes such as the US. EPA’s Clean Power Plan and China’s
recent legislation on coating VOC levels3
will continue to drive demand for greener chemistry
and coating processes. For coil coaters and other industrial coating users of organic solvents,
the trend is identified. The value chain supporting EB curing for coil other industrial coating
applications is there, technologically ready and waits to be engaged.
REFERENCES
Advances in Coil Coating Technology: 43rd
ECCA Autumn Congress,
23-24 November, 2009, Brussels, Belgium
3
Based on regulations imposed in early 2015, coating producer in China must now pay a 4% tax on the
invoice price of any coating whose ready-to-spray VOC level exceeds 420 g/L.

11
Fischer, W., Kuczewski, H., Rappen, D., Weikard, J. (18-20 October, 2005). Urethane Acrylates
on Metal Substrates. Paper presented by Bayer MaterialScience at RadTech Europe
Conference held in Barcelona.
Epstein, J. (2008, April 1). The EB advantage: Modern EB curing technology can provide a
viable, cost-effective solution to complex curing challenges.(UV/EB TECHNOLOGY:
ELECTRON BEAM CURING). Finishing Today.
Lund, T., Laurell, B., & Foll, E. (2010). New Developments in EB Accelerators. RadTech Report,
(APRIL/MAY/JUNE 2010), 25-33.
Molenaar, F., Buijsen, P., & Smit, C. (1993). Adhesion of electron beam curable coatings on
metal substrates. Progress in Organic Coatings, 393-399.
Pilcher, G. (2012, February 1). Coil and Extrusion Coatings. Market Analysis Review.
Tyson, M., Rutherford, M., Testoni, A., & Epstein, J. (2008). Benefits of Compact Electron Beam
Adoption in Industrial Process: Case Studies on Energy and Water Savings and Reduced
Pollution Output and Chemcial Use. Clean Technology, 359-362.
i
Berejka, A. (2003). Electron Beam Curing of Coil Coatings. RadTech Report, (SEPTEMBER/OCTOBER 2003), 47-53.
ii
Golden, R. (2012). What's the Score? A Method for Quantitative Estimation of Energy Use and Emission Reductions for
UV/EB Curing. RadTech Report, (3), 44-48.
iii Swanson, K., & Joesel, K. (2013, February 26). UV/EB Technology for Coil Coating. Lecture presented at Uv.eb WEST 2013
Advanced Materials Conference, Redondo Beach, CA.
iv Page, C. (2015, April 7). A Case Study in Metal Coating Curing Innovation: Cleveland Steel Container Harnesses Electron
Beam (EB) Technology [Taken from telephone interview with John Salkeld, Marketing Manager PCT Engineered Systems
LLC].
v Industrial Radiation Processing with Electron Beam and X-Ray (1 May 2011 ed., p. 20). (2011). International Atomic Energy
Agency.

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