Conference Program

Tuesday, March 10, 2020

Break + Exhibits

10:00 AM – 10:15 AM

Lunch + Exhibits

12:15 PM – 1:15 PM

Break + Exhibits

3:15 PM – 3:30 PM

6935 Wisconsin Ave. Ste 207 · Chevy Chase, MD 20815 
uveb@radtech.org · 240-497-1242 · 240-643-0517

The impact of different intensities on the performance of LED cured coatings, highlighting the importance of homogeneous cure.

David Ivarsson, EFSEN UV & EB TECHNOLOGY

The UV-LED technology provides a number of great advantages, such as energy savings, long life time, low heat and no ozone / mercury. With LED technology, we rely on thousands of small LEDs to sufficiently cure our coating. What if there is a deviation along the width of the lamp? If a segment goes out, if some of the optics gets damaged or dirty, how does this impact the curing, and the final properties? This study aims to determine what level of deviation causes problems with insufficient cure. To prevent problems with insufficient cure, we have developed a proprietary technology, to continuously monitor the output of an UV lamp during production. Not only does this show us the complete picture of the UV output along the width of the lamp, it is also able to use the extracted information to adjust the power level of any segments that does not conform to the specification. This will provide an assurance, in real time, that all segments perform according to the specifications, and also lets you know directly when there is damage, dirt or other issues preventing a segment to perform to standard.

Application of Intelligent System Data to Curing Processes

Darrin Leonhardt, Heraeus Noblelight America

With the integration of sensor technologies in to industrial curing systems comes much anxiety and confusion for the end user as the external process conditions are compared to the new sensor information. This presentation will bring together the (in situ) internal sensor information and (ex situ) external process parameters/system operation from the Intelligent Irradiator (microwave lamp) system. Detailed comparisons between in situ and ex situ sensor readings will be provided to identify process dependencies of critical components (bulbs, magnetrons,…) and system operation (air flow, humidity,…). The direct effects and/or correlations between various measurements will also be used to identify areas of concern where blind spots may occur.

Safer UV products and increased yield with the ICAD® Technology

Thomas Efsen, EFSEN UV & EB Technology

ICAD® Technology is a new inline process control of UV light sources, enabling safer UV-cured products. Food Safe product and UV/UV-LED curing is enabled with ICAD® Technology. Manufactures will have 100% control of their UV/UV-LED process. This control not just ascertains correct curing parameters all the time, but also enables new features and benefits for end users of UV/UV-LED. This paper will show the current quality of UV/UV-LED in the field, and what is possible to do when manufactures constantly know the UV/UV-LED dose applied.

UV LED Curing Systems: Measuring accurately and eliminating safety hazards

Geri Tangdiongga, Dymax Asia Pacific Pte Ltd

The UV LED technologies are progressing very rapidly in the recent years both in performance and in cost. Therefore, the measurement equipment and methods for UV LED curing systems are required to be better understood. This paper focuses on the trends of measurement and characterization of the UV LED curing systems especially in the UVA range. Moreover, the risks and safety concerns of UV light will be discussed in the paper, especially illuminating the inherent advantage of LED.

Divide to Conquer: Practical considerations for measuring the output of commercial UV LED sources

Jim Raymont, EIT Instruments

This paper compares the merits of a one-size-fits-all broadband approach to measuring UV LED light sources, versus a narrower-band approach to LED measurement. The authors examine the impact of commercial binning practices on the design of commercial UV LED arrays. The empirical results suggest that while the simplicity of broadband devices is appealing, production UV LED arrays can have variations in spectral output that can cause inconsistent and inaccurate process measurement with a broadband approach. To account for the inherent variations in commercial sources, we examine the opportunity for multi-channel radiometers with separate LED bands to provide a more stable basis where reliable process control and monitoring is required.

A Photodiode-free Approach to LED Lamp Radiometry

Robin E. Wright, Wright Way UV Consulting LLC

A laser power meter developed by Coherent was modified and used as a profiling radiometer for LED arrays. The device combines the broad wavelength sensitivity, dynamic range, and damage resistance of a thermopile with the response speed of a semiconductor photodiode. The patented high-speed, thin film sensor technology for power measurement utilizes a unique thermal flow design enabling fast, high power measurement, with high damage resistance.

Don’t blink or you’ll miss it: The importance of sampling rate in monitoring UV LED curing applications.

Jim Raymont, EIT Instruments

Just as old-fashioned stop-action animation can appear choppy and disjointed; measuring UV processes can lead to inaccurate and misleading results if the measurement device operates (samples) at too slow a speed compared to what is being measured. UV radiometers sample and store data at a pre-programmed frequency, or sampling rate. Process speeds are approaching 500 feet per minute on some digital inkjet applications using LEDs. Current measurement devices can be set to an effective sample rate of 25-2048 samples per second. Is this fast enough? This paper examines the importance of selecting the proper sampling rate to account for various UV source parameters (for example the design of the LED array, the modulation scheme used to control the array’s intensity, and the optics, if any, used to disperse the LED’s output. Proper sample rate also depends on process parameters such as production line speed, or location of the UV LED array. This presentation will provide practical guidance for the proper use of sampling rates by drawing on real-world examples for end-users, formulators, and equipment suppliers who need repeatable, accurate UV process control.

Introduction to the Basics of UV/EB Curing

Dr. Mike J. Idacavage, Radical Curing, LLC

Material Solutions for High Heat Resistance in 3D Printing Applications

Brendan McGrail, Sartomer

Energy curable resins with high heat resistance are needed for many emerging applications. Highly crosslinked acrylate formulations are commonly used, but come at a cost of anisotropic shrinkage resulting in high internal stresses and poor mechanical properties at temperature. Methacrylates offer higher glass transition temperatures at equal functionality but have relatively low ceiling temperatures and a smaller pool of commercially available materials. We will discuss formulation and new material developments to achieve high temperature performance.

Processing of 3D Printed High Temperature Materials

Amelia M Davenport, Colorado Photopolymer Solutions

3D printing/additive manufacturing continues to be one of the fastest growing and exciting technologies for numerous markets. UV Curable 3D printing has numerous advantages for use in additive manufacturing because of its high resolution, good layer to layer adhesion, and the ability to customize resins among other positive features. This presentation will focus on printing high strength and temperature materials utilizing acrylate, hybrid acrylate-epoxy, and filled systems. Final material properties are evaluated and correlated across different printing platforms and postprocessing conditions. It is demonstrated that postprocessing methodologies have a significant impact on the final properties and weathering characteristics of printed parts.

Effect of post-curing process on the performance of automotive 3D-printed specimens

Forough Z. Shahraki, Eastern Michigan University

The final material properties of 3D printed parts that utilize UV curable resins are highly dependent on any post-cure processing used after printing. This post-cure step is needed to crosslink unreacted double bonds remaining after the print process is complete. However, differences in part geometry, pigmentation, stabilization, and resin formulation can make it difficult to employ a generic, one-size-fits-all post-cure process. In this study, the effect of the post-curing process on the mechanical properties of three different 3D printable, non-stabilized UV cure resin formulations (A and B with thiol-ene, and C with acrylate chemistry) was studied. To this end, type IV tensile bars were printed using a DLP printer and post-cured using one of five different processes: no post-cure, UV-only, thermal-only, UV+ thermal, and electron beam (EB) curing. Bulk tensile properties and nano-hardness values were measured for each of the formulations and post-cure conditions. Results indicated that thermal curing was not as effective as UV for system C compared to the two other systems, which could go under thermal polymerization as well. Also, regardless of the type of post-curing, system B showed the smallest change in mechanical properties before and after the post-curing. EB curing, even at very low dosages such as 1 Mrad, resulted in considerable embrittlement of the samples and a significant drop in their percent elongation at break. Overall, provided a suitable post-curing process is employed, all the systems demonstrated promising potential for automotive applications. Their performance is expected to improve even further after addition of hindered amine light stabilizers (HALS) to the resin formulations.

High-Performance Monomer Development for 3D Printing

Kyle Snow, Sartomer

UV-curable resins based on combinations of (meth)acrylate monomers, oligomers, and photoinitiators have found substantial commercial application in DLP and SLA additive manufacturing techniques. While high resolution of complex geometries and superior surface finish can be achieved with these techniques, the mechanical properties attainable with (meth)acrylate photopolymers can fall short of what is needed for functional parts. As a necessary component of any 3D-printable formulation, monomers serve as reactive diluents for higher-viscosity oligomers to target printable viscosities and play a significant role in influencing the cured mechanical properties of a resin. This paper will highlight recent developments in Sartomer’s growing monomer portfolio, opening new formulation possibilities and pushing the limits of photopolymer resins performance in 3D printing.

Novel UV hybrid PVDF aqueous dispersion for flexible exterior applications

Anna Johnson, Arkema Inc.

PVDF-acrylic hybrid dispersions have demonstrated exceptional weatherabilty, color fastness, mold-mildew resistance and dirt pick up resistance in exterior coating applications. As construction materials become more lightweight and flexible, coatings systems require greater flexibility without sacrificing their intrinsic protective and aesthetic properties. The proposed solution is a novel PVDF aqueous dispersion designed to work in combination with UV crosslinking mechanisms for factory and field applications imparting the full balance of properties, while meeting stringent VOC regulations.

Novel Light Stabilizers for Waterborne and Functional Coatings

Arun Patel, Everlight USA

According to the surveys of ACS 2018 and ECS 2019, most participants thought waterborne and functional coatings would be the most important future technology trends in the coatings industry. Waterborne coatings are becoming increasingly popular, widely being used in many indoor and outdoor applications. Functional coatings are more focused on certain functions to make us live better. Nevertheless, it can be a challenge when conventional light stabilizers are required to be induced in the formulation for protecting coatings from UV degradation. Everlight Chemical has committed to develop new light stabilizers to fulfill the demands of the coatings industry for over 25 years and already launched over 15 waterborne products into the market. In this study, we solved the problem of instant yellowing in UV-curable waterborne coatings, conducted research on wood coatings’ lignin issue, and developed a full solution on reversible thermochromic coatings made from UV-curable, waterborne and solvent borne processes.

Energy Curable Oligomers for Exterior Building Products

Jonathan Shaw, allnex

UV curable industrial coatings have largely been centered around interior products, with the notable exceptions of automotive forward lighting and window films. The UV value proposition of increased productivity also applies to exterior products for buildings and interest in these UV products is growing. This paper will present real time and accelerated weathering data for several UV oligomers, along with formulated product results related to adhesion, hardness, stain resistance, etc. applied to multiple substrates (e.g. wood, or vinyl).

Enhancing Resolution And Fidelity While Decreasing Anisotropy Using Raft Agents In Stereolithography

Allan Guymon, University of Colorado

Stereolithography (SL) continues to show great promise for small-volume manufacturing and rapid prototyping because of its ability to relatively quickly create objects with intricate 100 µm or smaller features. However, widespread adoption of SL faces a number of obstacles including unsuitable thermomechanical properties, anisotropic properties, and limited resolution and fidelity. In this work, we explore the benefits of incorporating a reversible addition-fragmentation chain transfer (RAFT) agent into a glassy acrylate formulation to modify mechanical properties and improve resolution of objects printed using digital light processing (DLP) SL. Incorporating a small amount of a trithiocarbonate RAFT agent into the formulation leads to increased elongation and toughness accompanied by a small decrease in tensile modulus. To determine anisotropic properties of DLP SL, samples were printed in “horizontal” or “vertical” directions, where the long axis of the sample was printed in the x-axis or z-axis, respectively. RAFT samples printed in a vertical orientation exhibit a higher modulus than non-RAFT controls prior to post-cure in addition to a similar modulus with increased toughness upon UV post-cure due to the living/controlled nature of RAFT polymerization. Furthermore, incorporating a RAFT agent into the formulation allows significantly higher fidelity printing of a broad range of positive and negative features as small as 100 µm. The RAFT formulation allows objects to be printed with significantly better fidelity than non-RAFT formulations, even when a radical scavenger is incorporated to mimic reaction rates observed from the RAFT formulation. Additionally, the RAFT agent significantly increases the critical energy parameter determined from the SL working curve, indicating an increase in gel point conversion. This work demonstrates the benefits of using controlled/living polymerization in a highly cross-linked acrylate system to improve toughness, modify anisotropic properties, and print high-fidelity features with enhanced properties in 3D printed materials.

Resin Design for Spatial Control of Photopolymerization In Volumetric Additive Manufacturing

Caitlyn Cook, Lawrence Livermore National Laboratory

Photopolymer-based volumetric additive manufacturing (VAM) enables complex 3D structures to be built in a single step [1]. In contrast to traditional stereolithography (SLA) technologies, VAM projects 3D light patterns into the volume of photosensitive material thereby simultaneously curing all points within a target geometry. Parts form “all at once” on timescales of 10s to 100s of seconds, with no need for support material or a substrate. The most promising implementation of VAM is known as computed axial lithography (CAL) [2] which adapts principles of computed tomography (CT) to build up a 3D distribution of optical energy, which in turn, solidifies the desired part in a photocurable resin. Optical energy is delivered via a dynamic DLP projector pattern beamed into a rotating resin container. Building a part volumetrically requires greater spatial control over the polymerization reaction than with traditional layer-by-layer SLA approaches. Here we demonstrate this approach while comparing conventional acrylate chain growth and thiol-ene step-growth photopolymerized networks and photokinetics. Identical isocyanurate and polyethylene glycol-based monomers were selected, and reactive functionality was modified for direct comparison. Mechanical tunability and toughness are increased when using thiol-ene monomers, providing a toughness of ~35 MJ m-3 and 200% strain at ambient temperature, comparable to conventional thermoplastics. Thiol-ene polymerization induction period, propagation kinetics, and extent of conversion are optimized via photoinitiator concentration and various inhibitor species with a range of inhibiting mechanisms. An understanding of volumetric dose and its relationship to the threshold behavior of the resin controlled by inhibitory species is presented. We use the results of exsitu measurements such as real-time FTIR spectroscopy, rheology during curing, and mechanical testing, combined with in situ monitoring of part formation to develop a quantitative framework for predicting volumetric structure formation and its resulting properties. Finally, we will compare volumetric dose results to 3D printing via traditional layer-by-layer SLA, suggesting that it is a special case of the more general volumetric polymerization framework.

Quality & Durability Improvements of 3D Printed Parts via Bio-Based Modification of Photocurable Resins

Nathan Noyes, Croda

Within polymer-based additive manufacturing, photocurable resin-based processes have gained acceptance due to advantages in printing time, surface finish, and interlayer adhesion relative to filament or powder fusion techniques. Still, serial production of functional parts via these 3D printing processes is isolated due to material limitations. Through modification of benchmark photocurable resins with bio-based (meth)acrylate derivatives based on dimer fatty acid technology, improvements in dimensional stability, water absorption, and toughness have been demonstrated which enable greater functionality and durability of printed parts.

Effects of Structure and Composition on Mechanical Properties of UV Systems

Paul Share, Advanced Materials Design

The formulation of UV curable compositions for 3D printing requires the simultaneous optimization of opposing properties. Increases in cure speed, desirable for manufacturing throughput, can lead to brittleness, curling, and storage instability. Increases in tensile strength and impact resistance, desirable for structural components, can lead to poor flexibility and low elongation. Increases in elongation, desirable for elastomers, can lead to surface tackiness and poor tear resistance. There is also a limited range of acceptable formulation viscosities unique to each 3D printing technology which further confines the optimization space. In this presentation, a systematic synthesis and statistical mixture design study of the effects of oligomer structure and monomer formulation composition on the resulting mechanical properties of UV cured systems will be described.

Enhancing scratch resistance of UV curable coatings for wood products

Aurelien Hermann, University Laval

Finding the balance between low gloss and high mechanical performance remains challenging for the industry of wood flooring. This work aims to investigate the addition of dendritic materials in UV-curable coatings and to characterize the mechanical properties of the resulting coatings. Thanks to their high functionality, good flexibility and viscosity, dendrimers enhance the conversion of acrylates, polymer crosslinking density and scratch resistance. Moreover, they promote the incorporation of inorganic charges in the formulations.

UV Curable Oligomers for LVT – Enabling Differentiation

Jonathan Shaw, allnex

UV curable hard coats are used to produce high quality, stain resistant, wear resistant and scratch resistant LVT tiles that perform extremely well in every day use. Manufacturers of LVT flooring need to find ways of differentiating their products from the competition. One such way is through improved stain resistance. With the advent of stiffer substrates, it is possible to improve stain resistance with higher crosslink density since curl is less of an issue. Hiding deep, white scratches by changing resin selection can also be advantageous for LVT manufacturers. The pros and cons of these two approaches will be discussed.

Renewable UV Curable Resins for Wood Finishes

Kevin Nance, Alberdingk Boley , Inc

More environmentally friendly and "greener” approaches to wood finishing are being driven by stringent regulations and consumer demand. This focus has resulted in a wide variety of new and improving technologies being developed to meet performance requirements while complying with environmental regulations. The use of waterborne (WB) UV chemistry is growing in the wood finishing market because of these environmental regulations. New developments in biobased oil containing WB polyurethane dispersions have yielded unique alternatives to the traditional polyurethane dispersions. The project scope of this work has been to focus on the development of biobased resins including 100% solids UV technology and waterborne UV, castor oil modified polyurethane dispersions for wood coatings. These resins show comparable performance against traditional commercial products in markets such as KCMA (Kitchen Cabinet Manufacturers Association). They offer eco-friendly alternatives with excellent chemical resistance, excellent application properties and overall exceptional performance at lower VOC levels.

Self-healing UV curable coatings for wood finishing system

Chloe Paquet, Universite Laval

For wooden flooring, mechanical properties are very important to preserve the appearance in time, such as abrasion and scratch resistance. This presentation will focus on the development of self-healing coatings, UV curable, using reversible bond. Hydrogen bond can be used, but the challenge is to get hard coating with enough chain mobility for the self-healing. The impact of the quantity of hydrogen bond on the glass transition, cross-linking density and self-healing behavior is studied.

New radiation curable oligomers with high renewable carbon content for coating and 3D-printing applications

Andreas Moeck, RadLab AG

Non-renewable resources such as natural gas and oil are limited in availability. Consequently, substantial efforts are being expended to develop alternative technologies for the manufacture of industrial chemicals, which utilize renewable raw materials. Due to the avoidance of VOC emissions and low energy consumption, radiation-curing technology is already recognized as a sustainable technology. With the use of radiation curable materials based at least partially on renewable raw materials end-users can develop new formulations with improved carbon footprints and therefore achieve another level of sustainability. Here, we report the successful fabrication of new acrylic oligomers with a renewable content ranging from 55 to 80%. The extraordinary mechanical properties of these new resins in the targeted coating and 3D-printing applications will be discussed.

Copper Printing by Digital Light Processing Stereolithography

Roumanie Marilyne, CEA/LITEN

Highly thermal and electrical conductive material, copper is used in renewable energy and power electronics. Manufacturing complex parts are required to develop new generation power generators and electrochemical management systems. Metal stereolithography is a 3D polymer/metal technology, based on UV photocrosslinking process. The printing step is followed by a thermal treatment to obtain metal copper parts. The investigations on copper/acrylates formulations and properties of sintered copper parts, C&O contents and thermal conductivity, will be discussed.

Binder development for the 3D printing of Ceramic

Yann Stolz, Sartomer

3D printing of ceramics by photocuring techniques has shown tremendous results over the past few years, becoming the most widely used form of printing of technical ceramics using suspensions based materials. Thanks to the development of high resolutions parts with very high surface finish, this technology has started to find its place in sensitive fields such as aerospace or dental. However, ceramic powder loading, density and part fidelities are still challenges that need to be addressed in order to compete with other existing ceramics technologies. In this presentation, we will discuss work done on the development of suitable photocurable binders to improve the overall printability and properties of the ceramic parts produced on SLA/DLP systems.

Digital Light Processing Stereolithography and Si(O)C Manufacturing

Roumanie Marilyne, CEA/LITEN

Silicon Carbide (SiC) is a high performance ceramic used in high temperature environment (refractory, brakes) and power devices and modules. Stereolithography is known to print 3D complex ceramic parts compare to conventional ceramic process. However, SiC powder strongly absorbs the UV light, inhibiting the resin photopolymerization reaction. Polysiloxane and polycarbosilane are Si(O)C ceramic precursors, consistent with UV process. The work on UV-curable ceramic formulation and the composition of the final material, will be reported.

UV-Curable Acrylate Resins for Difficult Substrates

Chakrapani Srinivasan, IGM Resins

UV-curable coatings have penetrated applications hitherto dominated by conventional coating technologies. Applications on difficult substrates require specialized acrylate resins capable of maximizing adhesion to the substrates, coupled with exceptional physical properties (chemical and abrasion resistance). Examples include low surface energy BOPP films, variable wood substrates, luxury vinyl flooring, and electronic assemblies (high adhesion under adverse thermal and chemical conditions). We quantify the challenges, demonstrating how specific acrylate resins selections simultaneously optimize adhesion and physical performance.

Formulating strategies for adherence to difficult substrates

Chris Orilall, Sartomer Americas

An overview of Energy Curable Adhesives such as UV/ EB Pressure Sensitive Adhesives (PSA), Laminating-type adhesives (wet and dry) as well as peroxide and amine initiated type 2K adhesives. Here, we will review structure-property relationships between formulation and adhesive properties such as tack, peel, shear and temperature performance. We will highlight the importance of viscosity-elastic properties and formulating strategies for adhering to ‘difficult’ substrates such as polycarbonate, untreated PP, PET, glass and nickel plated steel.

Enabling energy curable adhesion through polymer design

William C. Miles, Penn Color, Inc.

Energy curable systems are outstanding options for many different applications, but have limits because of difficulty achieving adhesion on low energy substrates. Penn Color has developed a patent-protected polymer that can be solubilized into monomer systems that greatly enhances wetting – and thus adhesion – of energy curable systems. This is achieved using a mechanism that relies on polymer architecture rather than surface tension, meaning that the wetting can be achieved across many different substrates.

Innovations in Dual Cure Technology

Chris Baumgart, Red Spot Paint and Varnish

The ever-increasing demand for scratch resistance, chemical resistance, and improved appearance has spurred a new development of coatings for automotive applications. Dual Cure coatings bridge the strengths of typical UV and thermal systems while adding the benefits of micro scratch and mar minimization. This emerging technology addresses performance requirements and provides finishers the benefit of adapting and retrofitting existing paint lines.

Hybrid Radiation Curing - UV/LED & Excimer

Chris Davis, IST AMERICA

Hybrid radiation curing continues to draw interest, as it is a singular curing platform that offers the relative advantages of UV, LED and Excimer. With ongoing development in formulations and their corresponding energy requirements, this presentation will review the current technology status and illustrate applications that are ideal candidates for this new platform.

Comparison of UV and EB processing on Structure Property Relationships

Jon Scholte, Sartomer Americas

Acrylates are a common family of monomers that produce quick curing and robust properties. These monomers can undergo polymerization from multiple sources including light and electron beam radiation. Herein we will discuss the similarities and differences in processing and properties based on initiating source. We will highlight the changes to mechanism and how to predict necessary changes to processing based on monomer structure.

Investigation of UV/EB dual cure method to mitigate oxygen inhibition

Sage Schissel, PCT Ebeam and Integration, LLC

Nitrogen inertization is typically used to mitigate oxygen inhibition during EB polymerization. However, continuous nitrogen flow is expensive, and it is desirable to identify a cheaper method to overcome oxygen inhibition. A spray method in combination with UV/EB dual cure was investigated as a means to overcome oxygen inhibition, while reducing the required amount of photoinitiator in the formulation. Successful reduction of the oxygen inhibition layer was quantified using confocal Raman microscopy.