2010 UV & EB Technical Conference Proceedings
Table of Contents

Monday, May 24, 2010

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Analytical & Measurement

Melting Point Depression of UV-irradiated Poly(lactic acid) Film

Gwang-hoe Koo, Eun-min Kim, Jinho Jang

Crosslinking structure can be effectively introduced into Poly(lactic acid) (PLA) by UV irradiation in the presence of a small amount of photoinitiator. Gel fractions of the crosslinked PLA samples increased with the increasing UV energy and photoinitiator concentration. The crosslinking lowered or even removed both the melting point and cold crystallization enthalpy of the PLA. The improved thermal stability of the crosslinked PLA was also indicated in thermogravimetric analysis.

On-line GC/MS Identification of volatile organics formed during the UV irradiation of polymeric materials

R. R. Freeman, T. Yuzawa

One aspect of material characterization that remains problematic is the identification of volatile compounds formed when a polymeric material is exposed to light, oxygen, heat and moisture. This has made the elucidation of reaction pathways a matter of deductive reasoning rather than being based on direct measurements. In addition, the performance of various additives may also be affected during UV-curing or day-to-day exposure.    This presentation describes a PY-GC/MS system that can capture, separate and identify compounds formed as a material is irradiated. The irradiated sample can then be analyzed in order to determine the effects of the irradiation on the polymer itself. Chromatograms of the volatiles formed when polycarbonate, polystyrene, polypropylene and various methacrylates are irradiated will illustrate the utility of the PY-GC/MS technique.

Characterization of heterogeneity in polymerization induced phase separated all methacrylate system

Carmem S. Pfeifer, Jeffrey W. Stansbury

Polymerization induced phase separation allows for the formation of hybrid structures, which can be tailored either through composition or processing conditions to optimize properties like volumetric shrinkage and mechanical strength. This study demonstrates heterogeneity formation in all monomeric photopolymerizable binary systems (such as Bisphenol-A-glycidyl dimethacrylate and Isodecyl methacrylate) through dynamic mechanical analysis, as defined by the broadening of the tan delta peak, and reaction kinetics (near IR), which shows two-stage slopes for selected compositions.

Measurement and Management of Stress Development in Photopolymer Networks

Jeffrey W Stansbury, Carmem S. Pfeifer

The formation of glassy, high modulus polymer networks with conventional crosslinking monomers is accompanied by significant volumetric shrinkage that in turn, leads to the development of internal and external stresses. The analysis of conversion-dependent stress evolution, including real-time measurement several critical factors associated with stress development, will be detailed along with some examples of novel polymeric materials that provide either chemical or physical mechanisms for stress reduction.

Chemistry

Novel, multi-functional unsaturated polyester polyols: synthesis and application

Dong Tian, Jeffrey S. Ross

Caprolactone-based acrylated polyols are widely used in radiation curable coating formulations. The most commonly used such polyol contains two functional groups: acrylate and hydroxyl. The hydroxyl group reacts with (poly)isocyanates and other polyols to generate urethane, and the acrylate group makes the urethane radiation curable.  This paper reports a new method to synthesize novel, multi-functional unsaturated polyester polyols in a one-step reaction, and their applications in radiation curable flooring coatings.

Novel UV Curable Polyurethanes from Glycidyl Carbamate (GC) Resins

Umesh D. Harkal, Dusty Pfundheller, Andrew J. Muehlberg, Dean C. Webster

Glycidyl carbamate (GC) resins consist of urethane and epoxy functional groups in their chemical structure. GC resins can be crosslinked by amines or by self-crosslinking to produce coatings with an excellent combination of chemical and physical properties. In this study, a UV curable glycidyl carbamate resin was synthesized by reacting epoxy groups of GC resin with acrylic acid. Thus, acrylated biuret glycidyl carbamate (ABGC) resin was synthesized by reacting biuret glycidyl carbamate (BGC) resin with acrylic acid. The product was characterized by FTIR and NMR. UV curable coating formulations were made by using ABGC resin and three reactive diluents. The coating performance was studied by evaluating the coating properties such as curing time (dry-through time), hardness, flexibility, solvent resistance and adhesion. Two control resins were also used to compare the formulation window and coating performance. UV cured coatings made from ABGC resin showed a wide formulation window and better performance compared to that of the controls.

Branched Radiation Curable Polyurethane for Coil Coating

R.N. Jagtap, G.N. Manvi

ABSTRACT   UV curing prepolymers  were synthesized by using newer type of polyol which is blend of Polyether and Polyester polyol, Isophorane Diisocyanate (IPDI), Hydroxy ethyl metha acrylate (HEMA). Three different formulation of polyurethane-acrylate (PU-Ac) were synthesized using  polyol in which ratio of polyether to polyester content were varied. Then these PU-Ac. Were characterized using Fourier Transform Infra Red Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), Universal Testing Machine (UTM) and Gloss. Various coating properties such as Scratch resistance, Chemical resistance, Adhesion, Solvent resistance, flexibility etc were evaluated.

UV Curable Biostatic Monomers: An Evolutionary Leap in Biomaterials

T. Brian Cavitt, R.A. Herrington, P. Hendley, J.R Lowe, A.R. Dodds, D. Smith, R. Isenhower, T. Brian Garfield, R. Carstens

China Session

Tuesday, May 25, 2010

Development and Manufacture of New Generation VOC-Free Photo-initiators

David Zhigang Wang

Electron Beam

Quick and Easy Way to Characterize Low Voltage (80-125 kV) EB Accelerators Using Fast Check Strips

Im Rangwalla, Alex Mejiritski, Oleg Grinevich, Mike Swain

With the increased use of low voltage Electron Beam accelerators for curing coatings, inks, laminating adhesives and cross-linking films for packaging applications, there is an increased demand to accurately, quickly and easily measure the required dose delivered to the product.  To meet this demand, Energy Sciences collaborated with Spectra Group Ltd. and has developed a quick and easy method to characterize the output of these accelerators accurately using EB Fast Check V2 strips. These strips are very easy to handle, read by a small color densitometer, and are fit for industrial use. They are not affected by temperature and humidity. These Fast Check strips are traceable to NIST via calibration through ASTM compliant standard dosimetry techniques. Details of the performance of these Fast Check strips in terms of repeatability, reliability in evaluating these low voltage EB accelerators will be discussed.

Use of Modular, Low Voltage EB Systems for the Surface Treatment of Complex 3-D Objects

Anne Testoni, Somchintana Norasetthekul

This paper will review the challenges in performing electron beam radiation treatment of complex, three-dimensional objects such as pre-filled syringe tubes, bottle performs and beverage pouches.  Strategies will be presented for: 1) guiding electrons around corners and into high aspect ratio features; 2) measuring adsorbed dose on non-planar surfaces; and 3) ensuring safe material handling.  System configurations that exploit the unique advantages of modular, low voltage electron beams, will also be shown.

Adhesion Promoters for EB Cure

Alexander Polykarpov

Equipment

New Super-Portable UV Curing Equipment

George Wakalopulos, Christy A. Dennis

Magnetic ballasts have limited the portability of mercury lamps for decades, while new electronic ballasts trade-off weight against cost and simplicity.     We’ll describe the lightest, most powerful, and economical UV equipment in the world today, for hand-held and floor curing applications.  These systems work directly from standard 120 / 220 volt outlets without any heavy or costly power supplies.  Lamps run at 300-500 watts / inch while curing widths from 20 to 60 inches.

Investigating the practical issues of nitrogen inerting in UV curable processes

Dawn Skinner

This paper will investigate the practical issues surrounding the use of nitrogen inerting in UV curable processes.  This will include the evaluation of various photoinitiators and their effectiveness when curing under nitrogen; together with the application conditions and film thickness for the coatings.  In addition, other external influences experienced when curing under nitrogen and their effect on reactivity will also be examined.

Non-Reciprocity of Exposure of UV-Curable Materials and the Implications for System Design

R. W. Stowe

Using exposure data of various (mostly commercial) coatings, inks and paints, this study demonstrates that differences in irradiance profile will result in different material behavior (properties) and consequently, exposure requirements.  Using various quantifiable performance characteristics (including FTIR), this study demonstrates the reciprocity failure of UV exposure.   This paper introduces the "E-IP" chart for UV curable materials and simple methods for creating it.  To differing degrees, curable materials will exhibit different E-I   Using exposure data of various (mostly commercial) coatings, inks and paints, this study demonstrates that differences in irradiance profile will result in different material behavior (properties) and consequently, exposure requirements.  Using various quantifiable performance characteristics (including FTIR), this study demonstrates the reciprocity failure of UV exposure.  This paper introduces the "E-Ip" chart for UV curable materials and simple methods for creating it.  To differing degrees, curable materials will exhibit different E-Ip thresholds of physical property development.  Evaluation of the non-reciprocity of any subject material is important to 3-D and multi-lamp system design.  It also leads to more precise and more useful exposure requirement specifications for commercial materials, and provides a means of communicating material responsivity essential for production design.

UV Spectral Stability as it Relates to UV Bulb Temperature

Jim Borsuk, David Armitage

For optimum efficiency of the UV curing process, the material to be cured, needs to be matched to the specific spectral output of a UV bulb, also referred to as the UV light wavelength. This match is paramount to proper curing and thus, the success of any curing process. Factors such as formulation of the UV material, material thickness and speed of the process all play an important role in selecting the correct lamp. However, without proper cooling, the critical wavelengths may shift, negatively impacting the curing application.   This paper will analyze the various methods of cooling that will provide consistent, reliable spectral output for a UV system, regardless of lamp type.

Erinn Test

Erinn Kruser

Equipment - LEDs

LED curing - reaction/behaviors of various inks to LED based UV sources

Guomao Yang, Sola Kuk, John J. Kuta

Recent advances in LED technology make high power LED based UV sources a viable solution for the curing inks in digital printing applications (Both peak intensity and total power of new LED based UV systems from several leading LED UV system suppliers have reached the minimum requirement for digital printing applications). Due to the numerous potential advantages of LED based UV sources, such as less energy consumption, reduced heat load on substrate, longer system lifetime, etc., more attention has been paid to LED based UV sources while people try to implementing UV curing technology for digital printing applications. However, the direct replacement of discharge lamps with LED systems is complicated by the fact that there are many differences between the two sources, most importantly the spectral content. Ink formulations optimized for conventional gas discharge lamps, which typically have multiple emission peaks from deep UV to IR range (broadband source), take advantage of the multi-wavelength source as well as other parameters to guarantee a high quality print, such as adhesion, flexibility, chemical resistance, etc.  Ideally, ink formulations remain the same while the curing source shifts from gas discharge lamp to LED.  For this reason, it is necessary to study how the inks react to LED based UV sources, for optimization of the  LED system during development and for integrators who are planning to use LED based UV sources in their printing systems. EXFO LSI has performed a series of experiments with various types of UV curable inks, investigating their curability with LED based UV sources.  Since the shortest wavelength high power LED source is 365nm, results show that surface cure issues are more pronounced when using an LED source due to the lack of shorter wavelength UV emission.  Although LED sources are successful in ‘getting the job done’, a high UV dose is needed to cure conventional UV inks.  Modification of the ink formulation to enhance the cure efficiency of LED based UV sources can reduce the need for UV power dramatically.

Low Energy Curable Coatings

Marcus Hutchins, Stephen Smeets

Traditional energy curable coatings are often cured with high powered lamps. These lamps create ideal curing conditions by generating high light intensity, broad spectral distribution and enough heat to limit the effects of oxygen inhibition during cure.  However, those benefits are known to actually be drawbacks for certain applications with sensitive substrates. For instance, the high light intensity and heat generation can become problematic to substrates which are sensitive to light and heat. Other known deficiencies of high powered lamps include poor lamp/energy efficiency,  too broad a spectral output and difficult adaption to portable devices. Such limitations have promoted the growth and development of two types of curing equipment.  One uses low energy Ultra Violet irradiance (UVA section of UV light), and the other uses short wavelength light emitting diodes (LED).   UVA and LED technologies feature lower light intensities, narrow spectral output, and decreased heat generation during cure. Under these low energy curable conditions, traditional energy curable coatings have been found to be lacking.   In order to maximize curing and product performance under UVA and LED conditions, a better understanding of these technologies was required and new types of materials needed to be developed to maximize cure and achieve the requisite performance.  This study reviews the current UVA and LED technologies and introduces a new energy curable coating that maximizes cure and performance under UVA and LED curing conditions.

UV-LED Curing - Beyond the Early Adopters

Michael Beck

This presentation will review current "state of the art" in UV-LED curing and will look at the successful areas of application as well as the challenges that still exist. The paper will include analytical data from curing experiments with different UV curable materials that highlight the effects of proper formulation to maximize the benefits of UV-LED systems.

Measuring the Output of UV LEDs

Jim Raymont, Abhinav Kashyap, Robin Ovington

As UV lamp technology changes, so must the tools we use.  The evolution of UV LEDs to cure inks, coatings and adhesives is having an effect on UV measurement equipment and technique.  LEDs are narrow bandwidth sources whose output typically falls in the 365-395nm region.  Contrasted to medium pressure microwave and arc lamps, which emit across a broad spectrum, LEDs have high output in a very limited spectral region.  This paper will address some of the confusion arising from the specification and measurement of UV LED sources. We will address the need for correct filtering, the complications posed by LED optics and other characteristics of LEDs that has led to the development of new radiometers and the establishment of a new spectral band designation, A2, for these devices.

Formulating Coatings Optimized for UV LED Curing

Paul Mills, Ben Curatolo

LED’s: Shedding a New Light on UV Curing

Richard Jones, Shaun Herlihy, Nick Ivory, Kumar Menon, Nigel Caiger

Formulation of Coatings

Recent advances in photocuring and stabilization of water-borne coatings

Eugene V. Sitzmann, K. O. Sass, I. M. Spinu, K. P. Milks

The recent advancements in resin and additive technologies have permitted the engineering of highly durable (weather resistant) UV curable water-based coatings. These types of coatings are designed to be eco-friendly, have low or negligible VOC, and be able to rapidly crosslink and cure under UV light. The finished coatings exhibit high transparency and low color. They effectively remain unchanged for many years.    These types of coatings are very attractive for decks, wood, plastics, glass or other common materials requiring and protection against UV light.  The trick is to achieve the performance is the selection of the right resin along with an optimal photoinitiator and light stabilizer package.  A BAPO based photoinitiator package was developed to work with special UV blockers in water-based media, to achieve the desired UV cure speeds and also the UV blocking power in the final coating. It was found that the new nano-encapsulated technology (NEAT) based light stabilizers were provided distinctly enhanced photo-stability of these water-based UV curable coatings.

Novel organic-inorganic hybrid nano-composite coatings by UV-initiated sol-gel process

Scott Ryan Zavada, Vijay Mannari

UV-cure coatings have become systems of choice for plastic substrates, primarily due to their low-temperature cure, absence of potentially harmful solvents, and rapid curing. Free-radically curing acrylate resin systems are the most commonly used ones for commercial UV-cure systems for plastics. However, these systems have such inherent limitations as oxygen (air) inhibition of curing, poor substrate wetting, shrinkage, and odor that often limit their applications.  A novel chemistry, utilizing silane compounds, has been explored to study its suitability as an acrylate-free UV-curable system. We have demonstrated that such systems undergo cross-linking reactions through UV initiated sol-gel process resulting in the formation of hybrid organic-inorganic nanocomposite films. A systematic design of experiment (DOE) methodology has been used to study the effects of various parameters on the properties of the nanocomposite films deposited on polycarbonate substrates.

Use of Novel Matting Agent in UV Cure Coatings

Maria Nargiello, Hans_Dieter Christian, Reinhard Behl, Andreas Feller

While many technical advances have been made to produce low gloss, radiation curable clear coatings, they still present a challenge for most UV coatings manufacturers.  Matting agents have been developed where particle size, treatment and structure have been modified to achieve low gloss.  In this development, the combination of specific amorphous, synthetic silica combined with a specific Polydimethylsiloxane surface treatment was found to improve efficacy.  Based on this experience, a new product especially designed for low gloss, high transparency and low viscosity was developed for UV-Coatings.  This presentation will feature results comparing this new generation of matting agent to the matting technology considered “state of the art” in UV application.  The focus will be on gloss vs. viscosity behavior.  Photomicroscopy based on REM and TEM-Thin-Cut will be shown to demonstrate the performance of this unique new of matting agent.

Global Market Overview

Korean Market Overview

In-Hyo Kim

Japan Overview

Takashi Ukachi

Japan Session

Application of electron beam to environmental conservation

Koichi Hirota, Durga Parajuli, Noriaki Seko

Kinetics

Analyzing Depth Profile of Double Bond Conversion as a Function of Film Depth and [BPh]

Rong Bao

Analyzing Depth Profile of Double Bond Conversion as a Function of Film Depth and [BPh]  R. Bao, Fusion UV Systems, Inc., Gaithersburg, MD 20878, USA             Abstract    An influence of different concentration of Benzophenone (BPh) on double bond conversion at different depths of UV cured films was studied using a new approach that is a combination of traditional FTIR and statistical calculation.  A combination of BPh and organic tertiary amines is frequently used to overcome oxygen inhibition at the outmost part of UV curable films in UV curing applications.  Self-contradictory of BPh in reducing oxygen inhibition at the surface of cured films and increasing inner filter effect on UV light intensity (I0) at the bottom of cured films was digitally demonstrated by using the new approach.  It is very important to correctly utilize [BPh] and other [PhI] to balance surface cure and through cure for a UV cured film.  By studying the depth profile of a conversion as a function of different BPh / N-Methyldiethanolamine (MDEA) mixtures, a optimum ratio of BPh and MDEA was found for a formulation of EB8402 / SR506 (3:7) containing Irg. 184 1.94% or Darocur 1173 1.94%. This investigation was performed with a variety of film depth, different PhI mixtures, different ratios of BPh / MDEA in a PhI mixture in the presence of air and different I0 (mW/cm2) with equal UV Dose.  An efficiency of BPh / MDEA in different UV curable formulations was analyzed using the new approach. The depth profile of C=C conversion for a commercial “off the shelf” LCD trim coating was analyzed also. Propose of this paper is to help formulators and end-users learn how to correctly use [BPh] and correctly choose UV lamps to improve and balance the surface curing and the through curing in their UV curing applications.

Spectroscopic quantification kinetic rate constants for epoxy-acrylate hybrid photopolymerizations

Julie L. Jessop, Brian Dillman

Water serves multiple roles in cationic polymerizations and can significantly impact resulting polymer properties.  Contributions of active chain end (ACE) and activated monomer (AM) mechanisms in photopolymerization of 3,4-epoxy-cyclohexyl-methyl methacrylate (METHB) with and without added water have been determined using real-time near-infrared and Raman spectroscopies.  Formulations were also photopolymerized cationically and analyzed by gel permeation chromatography to determine molecular weight distribution, enabling further confirmation and characterization of the detrimental effects of water on epoxy formulations.

Nanotechnologies

Reactive Polymeric Nanoparticles for Composite Films

Janos Borbely

Nanocomposite Hydrogels by Photopolymerization

Janos Borbely

UV curing and sol-gel based chemistry: towards nanocomposite coatings in a one step process

Céline Croutxe-Barghorn, Abraham Chemtob, Cindy Belon

Cationic and radical polymerizations were implemented to generate hybrid organic-inorganic nanocomposites by a one-step photoprocess. This original and attractive route avoids phase separation and takes advantages of the UVcuring process.  Organoalkoxysilanes bearing photopolymerizable and trialkoxysilyl functional groups were polymerized in presence of photoinitiator that promotes simultaneously organic and inorganic network formation. The coatings were investigated by RTFTIR spectroscopy and NMR experiments. Thermomechanical analyses and scratch tests were performed on these nanocomposites highlighting the structure-property interdependence.

Engineering Optical and Mechanical Properties of Radiation Cured Inorganic-Organic Nanocomposites

Thad Druffel, Steven Isaacs, Omar Buazza

Radiation curable monomers offer a range of physical and optical properties while exhibiting high visible transparence. When their rapid polymerization potential is also considered, it becomes clear that these materials are ideal candidates for use in inorganic-organic nanocomposites. Our group has had considerable success incorporating up to 60 volume percent metal oxide nanoparticles in UV-cured polymers. The resulting materials exhibit a broad range of engineered mechanical and optical properties, while maintaining the polymers' flexibility.

Nanoparticle Additives for Enhanced Scratch-Resistance in UV-Cured Coatings

Roger H. Cayton, David Nelson, Patrick G. Murray

Additives based on metal oxide nanotechnology have experienced a slower than expected adoption rate in coatings applications.  These results may be due to a greater emphasis being placed on the innovative manufacturing technology and less focus on the value these Nano particles can deliver for customers in a specific application.  Utilizing a market-driven approach, a line of Nano-based additives has been developed that provide a breakthrough in terms of improved scratch resistance for UV-cured coatings for electronics, wood, and plastics applications.  These novel additives are delivered in a pre-dispersed format that must be optimized for a specific coating formulation to achieve step-change results.  Details of the market approach and additive performance will be provided for a range of coating applications.

THE EFFECT OF ORGANOCLAYS ON THERMOMECHANICAL PROPERTIES IN CROSS-LINKED PHOTOPOLYMER NANOCOMPOSITE

C. Allan Guymon, Kwame Owusu-Adom

To study structure-property effects of incorporating clay nanoparticles on the mechanical and thermal properties, Young’s modulus and Tg of multifunctional acrylate photopolymers are examined with increasing cross-link densities. Young’s modulus and Tg decrease substantially when organoclays are added to highly cross-linked polymer networks but increase in elastomeric polymers. The different effects of organoclays on the thermomechanical properties are attributed to the degree of disruption of the cross-linked network and surface interactions.

Packaging

UV Curable Coatings for Containers and Closures

Meagan Farley

The containers and closures market utilizes numerous decorating techniques on a variety of plastic and glass substrates.  These decorating methods need to be functional as well as aesthetically pleasing.  UV curable coatings can offer value to this market by providing high performance decorative coatings that are cost effective, easy to process and environmentally friendly.  This paper will discuss the benefits of using UV curable coatings as an alternative to other ways of decorating containers, some challenges encountered in formulating coatings to meet all specifications of the containers and closures market, and typical performance and processing requirements.

Low migrating UV curable clear coating as a barrier coat for direct indirect food contact applicati

Ayse Hancer

EB Gravure – Novel Printing Concept for Sustainable Packaging

Mikhail Laksin, Sean Evans, Ken Fontaine, Subh Chatterjee

Dual Ultaviolet and Electron Beam Curing of Printing Inks

Stephen Lapin

The combined UV and EB curing of printing inks was investigated.  The initial UV curing produced a partially cured ink layer.  The cure was effectively completed by subsequent EB irradiation without nitrogen inerting.  The advantages of dual UV-EB curing include: 1) ability to cure high density ink layers which are challenging to cure by UV alone, 2) ability to dry-trap multiple ink layers using relatively low power interstation UV curing, 3) assurance that all ink layers will be fully cured upon EB irradiation after the final print station, and 4) potential use in food packaging using low levels of migration resistant photointiators.

Photoinitiators

Cage Effect Dynamics under Photolysis of Photoinitiators

Igor V. Khudyakov, Nicholas J. Turro

Efficiency of photoinitiators (PI) depends upon quantum yield of photogeneration of reactive free radicals and upon cage effect value. Only radicals who escaped cage can initiate free radical polymerization.     The modern concept of the cage effect is presented.     Dependencies of the cage effect values upon media viscosity, which increases in the course of photopolymerization, are discussed. Cage effect dynamics or kinetics of geminate recombination is of special interest.      ns Laser flash photolysis study of  the cage effect under photolysis of PI is described.    Khudyakov et al. Photochem. Photobiol. Sci. 2008, 7, 1540.   Khudyakov et al. Phys. Chem. Chem. Phys., submitted

New visible light photoinitiating systems for free radical and cationic photopolymerization

Xavier Allonas, C. Ley, J. Lalevée, O. Tarzi, A. Ibrahim, M.A. Tehfe, J.P. Fouassier

Soluble and Red-shifted Sulfonium Salts

Yuxia (Sonny) Liu

A novel class of soluble and red-shifted sulfonium salt cationic photoinitiators will be discussed. They contain chromophores of aromatic ketone and aromatic sulfide, and linear or branched alkoxy groups.  The cationic photoinitiators have an adjustable solubility in UV curable compositions, efficient thick film UV curing, good thermal stability in UV curable compositions before UV cure, fast UV curing rates.

Photovoltaics

Influences on Barrier Performance of UV/EB Cured Polymers

Joshua Oliver

The use of UV/EB cured materials as barriers against moisture vapor and/or oxygen gas has long been discussed. Depending on the final requirements and thickness of application, UV/EB materials can be successfully used for this application. Unlike some polymer chemistries and films, UV/EB cured polymers cannot be classified together in terms of barrier performance.  Backbone chemistry, molecular weight, functionality, concentration of monomers or oligomers, hydrophobic/hydrophilic balance, density, cure conditions, and the presence of additives or fillers all play a vital role in predicting barrier performance.  These variables are explored as performance predictors and compared with real barrier testing results.

PV Cost Structures and the Role of Non-active Materials

Ted Sullivan

In light of the rapidly falling price of solar modules, the detailed cost structure of module manufacturing has increased in importance, especially as a way to determine the critical components of cost and examine the opportunity for cost cutting through 2015, both for active and non-active materials. Each of the major PV technologies: x-Si, TF-Si, CdTe, CIGS, and HCPV, will be examined to determine long-term winners.

PV Cost Structures and the Role of Non-active Materials

Ted Sullivan

In light of the rapidly falling price of solar modules, the detailed cost structure of module manufacturing has increased in importance, especially as a way to determine the critical components of cost and examine the opportunity for cost cutting through 2015, both for active and non-active materials. Each of the major PV technologies: x-Si, TF-Si, CdTe, CIGS, and HCPV, will be examined to determine long-term winners.

Material Needs for Photovoltaic Modules

Sarah Kurtz

Raw Materials

Evaluation of New Oligomers for UV/EB Lithographic Inks

James Goodrich

UV/EB litho inks continue to show growth and added utility in the printing ink marketplace.  Improvements in printing equipment technology have now placed more demands on the liquid ink printability and the cured ink properties.  Although the oligomers currently used in these inks have very good printing properties, there are deficiencies that need to be addressed.  In this project, the printability and cured ink properties of new acrylate oligomer backbones will be evaluated and compared to current technology.

Water-Reducible Urethane Acrylates: An alternative to UV-PUDs

Ahmet Nebioglu, R. David Zopf, Igor V. Khudyakov

Acrylated Products Designed for Formability and Adhesion Enhancement in Direct to Metal Applications

William Schaeffer, Robert Kensicki

Direct to Metal (DTM) applications require acrylated materials having the correct balance of physical properties including both flexibility and toughness. These features are necessary to ensure that the finished part will withstand the rigors of forming and handling without scratching and surface abrasion. Also the final coating must adhere to a wide range of metal types that may have surface contamination that make adhesion a challenge.    This work will investigate and report the performance results of end-use tests of oligomers having differing backbone structures used in combination with functional adhesion promoters. In addition corrosion resistance will be explored as a function of oligomer structure.

Enhancing Physical Properties of UV Cure Ink Systems

Charles S. Douglas, Susanne Struck, Ellen Reuter, Troy Moss

The environmental movement that is taking place around the world is causing formulators and end-users alike to reassess how they do business in a 'greener' world. Various methodologies are available to address the lowering of volatile content and include such measures as high solids, waterborne, exempt solvents, and energy curable technologies. The move to UV/EB curable technologies, particularly as it applies to the printing ink market, is growing at a faster rate than some of the previously mentioned ones. One of the key benefits of UV curable systems, besides being 100% solids most of the time, is its ability to effect almost instantaneous cure which increases productivity.  This paper will address the radically cross-linkable additives that allow these energy curable systems to achieve the final properties required for the coated surface.

Renewable Raw Materials

Sweet Soy-based UV Curable Coatings

Zhigang Chen, Jennifer F. Wu, Shashi Fernando, Katie Jagodzinski

Utilization of biorenewable chemicals in UV curable formulations satisfies future material need and provides a green solution to the stricter environmental regulations. Obtaining soy-based UV curable coatings with high biorenewable content and high coating performance is a technical challenge. In this research, synthesis and formulation approaches to tackle this challenge are explored. Modified UV curable sucrose (table sugar), and synthetic acrylates with unique molecular topology are found to effectively enhance the coating performance of soy-based, high biocontent UV curable coatings.

Design and Performance of Radiation Curable Acrylates with High Renewable Carbon Content

Jeffrey Klang

Radiation curing technology is widely recognized as a “green” or sustainable technology because of the avoidance of VOC emissions and low energy use compared to solvent or water based coating and printing technologies.  The use of radiation curable materials based at least partially on renewable raw materials brings another level of sustainability.  While renewable based radiation curable materials are currently being used commercially (primarily in printing inks), there are many opportunities to design new materials with higher renewable content and enhanced performance.  The properties of new materials with high renewable content in targeted coating and ink applications will be discussed.

Renewable / Sustainable Product Development: Green Chemistry vs. Energy-Curing Blues

Michael Gould

General product marketability has gained momentum in recent years by employing labels or definitions such as “green”, “renewable”, “sustainable” and “eco-friendly”.  Whether or not new products and technologies are truly any of these things, they are recognized more widely with each passing year as being ‘desirable’.      In technology-driven market segments that employ energy-curable coatings, adhesives and composites, “sustainable” and/or “renewable” product character has taken on greater potential value, both from a marketing and cost/performance standpoint.  However, in a challenging paradox, it is also widely assumed that bio-renewable (e.g. vegetable-based) raw materials utilized in the development of sustainable (i.e. non-petroleum based) products will deliver acceptable performance at LOWER cost than current raw materials.    A substantial research program undertaken by the RAHN Group has uncovered several interesting pieces of the oversimplified puzzle that is “sustainability”.  This presentation will explore both historical and current product development efforts.

Specialty Applications

The Role of 2-Acrylamido-2-Methylpropanesulfonic Acid in Conductive Medical Hydrogel Electrodes

Hyungsoo Kim, Geoffrey P. Marks, Carlos Piedrahita

Hydrogel, a lightly cross-linked polymer network, can swell substantially in water taking on hydrophilic and conductive character with potential for biomedical applications. This paper will explore the use of 2-acrylamido-2-methylpropanesulfonic acid in conductive medical hydrogels prepared via UV polymerization to make an electrocardiograph electrode. Different hydrogel formulation strategies, where parameters studied include crosslinker concentration, pH, water content, humectant, polymer composition and neutralizing salt, were systematically investigated to improve the properties including gel uniformity, moisture retention, conductivity and skin adhesion.

DEVELOPMENT OF UV CURABLE RESINS AND EVALUATION OF OPHTALMIC LENSES PRODUCED

Edison Bittencourt, Zaida Aguial, Marco Henrique Zangiacomi

Photo-reactive Coloration of Cotton Fabrics by UV irradiation

Yuanyuan Dong, Jinho Jang

Reactive dyes having photo-reactive groups were photografted onto cotton fabrics by UV irradiation using a photoinitiator and five hydrophilic monomers of AA(Acrylic acid), HEMA(2-hydroxyethyl methacrylate), VP(1-vinyl-2-pyrrolidone), ACMO(4-acryloylmorpholine) and DMAPMA(Dimethylaminopropyl methacrylamide). The reactive dyes were successfully photografted onto the fabrics. Moreover, color fastness properties to washing and rubbing of the colored cotton were good to excellent.

Next Generation Exterior Durable Hard Coats for Plastics

Kristy Wagner

UV curable hard coats have been used successfully in the automotive industry for over twenty years.  The latest generation of this coating technology is now entering markets other than automotive.  Coatings with exceptional scratch and abrasion resistance coupled with exterior durability are making inroads in the film and sheet industry.  These advances are allowing for greater penetration in the optical display, building materials, and the solar energy markets.

UV Curable Anti-Fog Coatings

Wenguang Li, Guido Meijers, Jens Thies, Atze Nijenhuis

Anti-fog coatings are needed on optical devices to prevent fogging and maintain the optical clarity in humid environment. In this paper, the development of new UV curable anti-fog coatings will be reported. The coatings comprise of inorganic nanoparticles and UV curable hydrophilic monomers and oligomers. The coatings can prevent fogging at temperatures between -20ºC and 90ºC. The coatings show excellent optical clarity as well as good hardness and scratch resistance.

UV Curable Powder Coatings for Heat Sensitive Substrates

Ryan Schwarb

UV curable powder coatings combine high performance material chemistry with low energy consuming and high speed finishing technology.  UV curable powder coatings are a rapidly developing segment of the coatings industry.  Low process temperatures and UV light initiated cure are ideal for substrates such as wood composites, plastics, porous metal materials, and pre-assembled parts with internal heat sensitive components.  This paper will focus on how combining UV cured powder coating chemistry with design requirements produce products of exceptional value.

Progress in the Development of UV Curable Topcoats for Military Aircraft

Satyendra K. Sarmah, Anthony J. Tortorello, Timothy E. Bishop

Two prototype UV curable coatings, a gloss white and a camouflage gray, were evaluated according to performance standards for military topcoats.  The coatings were benchmarked against two conventional USAF topcoats representing typical performance properties.  The two coatings were evaluated especially for hardness, adhesion, cold temperature flexibility, fluid resistance, color, gloss and accelerated weathering.  This paper will summarize the performance properties of each prototype coating.  Strengths and properties which need improvement relative to military specifications will be discussed.

Development of UV-A Curable Coatings for Military Aircraft Topcoats

Todd Williams, Michael Dvorchak, Charles Gambino

UV-A curable coatings are investigated as an alternative to traditional two-component polyurethane aerospace topcoats due to their rapid cure rates, low VOC, and high performance properties.  The development of a formulation that meets military specifications for aircraft topcoats will be described in this paper, and this paper will also review the results of recent field trials of a UV-A curable coating after 1000 service hours on a C-130.

Current State of the Art and Impending Developments in Silica Nanoparticle Use in UV Curable Systems

Mark Myers

Nanoscale colloidal silicon dioxide particles are currently widely used in UV-curable systems for surface abrasion resistance and in nanocomposites, among other applications. The use of silica nanoparticles as they are currently available is not without its drawbacks, however. The naturally hydrophilic surface chemistry of the silica particle has low compatibility with most UV curable resins and crosslinkers. Monodispersed silica nanoparticles are currently either provided in a volatile solvent  that must be substituted or removed, or are provided in a less-than-ideal low-functional monomer. This session will review the current use of silica nanoparticles in UV curable coatings and introduce new technologies which have been developed for delivering silica nanoparticles to UV curable resin formulations without the drawbacks of current solvent-borne or monomer-borne silica nanoparticle dispersions.

Thiol-ene Chemistry

Induction Curing of Thiol-ene and Thiol-acrylate Systems

Sheng Ye, Neil Cramer, Christopher Bowman

Induction curing is used to cure highly filled opaque composites comprised of thiol-ene and thiol-acrylate resins and various fillers including carbon black and carbon nanotubes which are infeasible to cure with traditional photopolymerizations.  Nanoscale nickel particles are dispersed in the resin to interact with the    induction field and induce curing.  Excellent mechanical properties are obtained from these composites.

Unique Polymerization properties of Thiol-Ene-Methacrylate Systems

Neil Cramer, Christopher Bowman, Charles S. Couch

Thiol-ene systems have advantageous polymerization properties in regards to rapid curing, high conversion, minimal oxygen inhibition, and reduced shrinkage stress.  Methacrylate systems exhibit excellent polymer mechanical properties for applications such as dental restorative materials, but exhibit low conversion and high shrinkage stress. The use of thiol-ene-methacrylate systems uniquely combines the advantages of both systems, decreasing the effects of oxygen inhibition, increasing conversion and biocompatibility, and decreasing polymerization shrinkage stress.

Stress Relaxation by AFCT in the Photopolymerization of Highly Cross-Linked Thiol-yne Networks

Heeyoung Park, Christopher J. Kloxin, Christopher N. Bowman

Radical mediated addition-fragmentation of mid-chain allyl sulfide functional groups was utilized to reduce polymerization-induced shrinkage stress in thiol-yne step-growth photopolymerizations.  The measured polymerization-induced shrinkage stress was significantly reduced in allyl sulfide-containing materials when compared with analogous propyl sulfide-containing materials, incapable of addition-fragmentation.  The resulting networks were highly crosslinked, possessing super-ambient glass transition temperatures and similar mechanical properties.

THE EFFECT OF ORGANOCLAY SYSTEMS WITH DIFFERENT FUNCTIONAL GROUPS ON PHOTOPOLTMERIZATION KINETICS

Soonki Kim, Allan C. Guymon

To study the effects of the type of functional group of organoclays on the photopolymerization kinetics and exfoliation behavior, acrylated and thiolated organoclays are incorporated into various thiol-acrylate mixtures. RTIR kinetic and DMA results demonstrate that thiolated organoclays facilitate great degree of step-growth thiol-ene reaction with higher thiol conversion and induce higher modulus. On the other hand, acrylated organoclays decrease reaction rate and do not increase mechanical properties to the some degree.

UV-Cured Membranes for Gas Separation

Luke Kwisnek

UV-curable thiol-based chemistries were used to fabricate polymeric membranes for separating carbon dioxide from gaseous mixtures.  Correlations were made based on network functionality, architecture, and the resulting gas transport properties.  CO2, oxygen, nitrogen, and methane permeability were studied as a function of testing temperature and input pressure for each membrane.  Such membranes can be used for gas purification or atmospheric scrubbing for life support systems and environmental sustainability.

Wednesday, May 26, 2010

Wood & Floor Coatings

Field Applied UV Curable Floor Coatings

Jo Ann Arceneaux

Coatings have been UV cured in industrial settings since the 1960s.   The graphics industry was one of the first to adopt this technology, with a high gloss coating on cards.  Today, there are numerous industrial applications that utilize UV curing as the method of drying or polymerizing their coatings or inks.  Many of these industries initially embraced UV curing technology as a way to increase both productivity and performance. More recently, the advantages of energy savings and environmental compliance have also led industries to choose UV curing technology.    In the past five or so years, commercial UV curing has moved out of the factory and into the field, with numerous improvements in UV curing equipment pushing this transformation.   Floor coatings are one of the main applications for field applied UV cured coatings.  Today, field applied or on site floor coatings for wood, vinyl, tile, and concrete are all in some phase of commercialization.     The benefits of UV cured field applied floor coatings are similar to factory applied floor coatings: increased productivity and performance.  In addition, the immediate cure aspect provides an added benefit of quality, since the finish will not be damaged once it is cured, and cost savings to the end user through immediate use.     This paper will review the performance of field applied UV cured floor coatings with that of conventionally cured floor coatings.  The benefits and detriments of each curing technology will also be reviewed.

Novel UV Curable WB chemistry for wood furniture applications

Jonathan Shwa

Sun Shine Cure Polyurethane Dispersion Deck Coatings

Chuck Gambino, Bob Wade, Michael J. Dvorchak, Karen Henderson

Coatings formulated with UV-cure polyurethane dispersions have become well established in the wood and furniture market over the last 10 years. Their high productivity, extremely low VOC and excellent performance have made them the standard by which  other water-based coatings systems are measured. BMS has now taken this concept into the exterior wood site-applied decking market. The concept is to have sunshine energy crosslink these low functional, high MW products instead of using an artificial UV light device to perform the cure   The paper will compare the performance of semi-transparent and opaque coatings that have been sunshine cured at different field sites. In addition, the paper will present data comparing sunshine cure against cure by full spectrum UV and UV A artificial light sources. This comparison will show that available sunshine provides enough energy to crosslink the high MW, low functional UV-cure PUD into a product that will provide several years of performance on exterior decking.

UV Curable Polyurethane Dispersion Coatings for Site-Applied Flooring

Ramesh Subramanian, Michael Dvorchak, Charles Gambino, Bob Wade

Quality Improvements in UV Wood Finishing

Gary Sigel

Abstract:     Finishing system requirements for wood flooring are based on Voice of  The Customer (VOC) as it relates to end user specifications including;  wood species, width, stain color, gloss, coating/wood visual, and overall durability and maintenance. Although multiple plants have UV finishing lines, varability in lines poses plant to plant differences in manufacturing for same product lines.  Controlling these differences has been a major part of our quality improvement efforts to allow for same products at multiple plants.    This paper reviews CTC (Critical to Customer attributes) and CTQ’s (critical to quality measurements for wood flooring finishing systems.  The associated CTQ’s reviewed include: UV stains with emphasis on quality improvement in color matching inter- and intra-plant using spectrometry, standardization of UV finishing system requirements, e.g., coating structure/performance, and statistical process control methodology for monitoring coating parameters and radiometry across multiple plants.