MITIGATING CHEMICALS OF CONCERN THROUGH THE USAGE OF NOVEL ENERGY CURABLE ACRYLATE TECHNOLOGY

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1 MITIGATING CHEMICALS OF CONCERN THROUGH THE USAGE OF NOVEL ENERGY CURABLE ACRYLATE TECHNOLOGY Anthony Carignano, Philippe DeGroote, Paul Gevaert, Luc Lindekens, Colette Moulaert, Rosalyn Waldo (Allnex) and Mike Rester, Andrea Suchy (Clariant Corporation) Allnex ABSTRACT Epoxy acrylates are one of the most widely used resins in energy cured inks, coatings and overprint varnishes for consumer product packaging and graphic arts. In addition to outstanding scratch and impact resistance, epoxy acrylates are known for their cost effectiveness. Bisphenol-A (BPA) is a building block for acrylated epoxy resins and in certain studies has been identified as a chemical of concern. The purpose of this presentation is to review what new chemistries are either currently commercially available or in development as resin system replacements for standard Bisphenol-A epoxy acrylates that would be appropriate for usage in consumer product packaging and graphic art applications. This presentation will take into consideration both conventional and bio-renewable approaches based on performance vs. cost criteria. INTRODUCTION Energy (UV/EB)-cured inks and coatings are well accepted in the graphics industry, and energy curing technology is recognized to offer numerous advantages over conventional technologies, such as high gloss, excellent resistance properties, high printing speeds, fast drying or cure times, no VOCs, and low system costs. Issues with possible chemicals of concern, however, including bisphenol A (BPA) and diluting acrylates, have presented challenges. Allnex has focused on developing a range of forward-looking solutions that address these issues in advance of potential future legislation. ALLNEX APPROACH TO CHEMICALS OF CONCERN For some time, there has been a need in the food packaging industry for resins used in inks and coatings that have minimal migration properties. By considering chemical properties, toxicity profiles and the overall manufacturing processes of its products, in 2008 Allnex introduced its EBECRYL LEO (Low Extractables Low Odor) portfolio that address this important issue. This comprehensive approach has already been extended to include the use of bio-renewable building blocks, and is now being applied to the development of solutions that address other potential chemicals of concern, including BPA. MIGRATION IN FOOD PACKAGING Although printing inks and varnishes are only applied to the non-food-contact side of food packaging, unless the packaging material acts as a true barrier (glass and aluminum), there is potential for ingredients in the ink or coating to migrate into food products or backside transfer during printing and conversion processes. In recognition of this issue, regulation of the ingredients that may come in contact with food has increased in Europe, the United

2 States, and China, and in some cases now consideration of impurity profiles, migration levels and manufacturing practices is required. With energy cured formulations, there is the possibility for migration of low molecular weight components, including diluting monomers (diluting acrylates), other additives, and photoinitiators. A HOLISTIC SOLUTION As a resin manufacturer with extensive expertise in UV cured technology, Allnex determined that it was necessary to tackle the problem of migration in a comprehensive manner, considering not only the properties of the final resin compositions, but extensively evaluating raw material options and manufacturing processes as well. To that end, for the new LEO line of products, only raw materials evaluated by the European Food Safety Authority (EFSA) are selected if possible, and no EFSA EU category 1 or 2, or CMR EU category 3 are considered. In addition, only very high purity materials are used in the production of EBECRYL LEO resins. LEO monomers are highly functional. Thus, increasing the size and cross-link density of the resin components minimizes the transfer of acrylates into food at levels above 10 parts per billion (ppb). In fact, EBECRYL LEO resins are designed in such a way that the residuals of EFSA-evaluated starting substances are below their specific migration limits (SMLs) for a worst case calculation. The migration properties of non-efsa-evaluated substances are experimentally determined and confirmed to be < 0.01 mg/kg. Allnex s MOC 1 and Good Manufacturing Practices (GMP) are utilized for all products in the EBECRYL LEO portfolio. In addition to using only raw materials that comply with stringent European Union and global brandowner specifications, EBECRYL LEO GMP practices include ensuring traceability of all materials along with documenting all operations and product compositions using pre-established instructions and procedures that minimize crosscontamination. Currently, Allnex offers a wide range of Low Extractable/Low Odor resins that offer ink, overprint varnish and coating makers formulating flexibility. Table 1. EBECRYL LEO range of Low Extractable/Low Odor UV curable resins for food packaging Resin Description EBECRYL LEO trifunctional acrylate diluent EBECRYL LEO low viscosity polymeric tetrafunctional polyether acrylate EBECRYL LEO low viscosity amine-modified polyether triacrylate EBECRYL LEO EBECRYL LEO EBECRYL LEO EBECRYL LEO medium viscosity amine-modified polyether tetraacrylate low viscosity polymeric amine-modified polyether tetraacrylate low viscosity modified epoxy acrylate polyester acrylate providing outstanding lithographic behavior and pigment wetting For food packaging applications where GMP practices are not an absolute requisite, Allnex has recently developed a second generation of Low Migration products. These resins offer the enhanced performance of EBECRYL LEOs but are not produced via strict Good Manufacturing Practice protocol. Thus, they offer a slightly more cost-effective solution for obtaining reduced migration properties. In addition, these products, such as IRR 778, 1 Management Of Change (MOC) requires that all changes in specifications, raw material processes and equipment etc. need to be approved by key persons in the organization before the change can take place. The change is typically initiated via Allnex MOC software. Pre-defined functions and approvers are notified and solicited for their change approval or dis-approval. For each change, there is a pre-defined template that must be used.

3 EBECRYL 437 and EBECRYL 570, were developed with adhesion to flexible nonporous substrates in mind. IRR 784 and EBECRYL 220 were added as second-generation low migration resins due to their abilities to boost reactivity. Although EBECRYL 220 does not have a low migration profile it is made with sn-free ingredients and represents the first in a line of sn-free product offerings addressing an unmet market need for organotin free UV/EB curable resins. IRR 783 was added to the low migration line-up as a high-purity, non-gmp diluting acrylate alternative to EBECRYL LEO Table 2. EBECRYL range of Low Migration UV curable resins for food packaging Resin Product Type Offset Flexo OPV IRR 783 Polyether tetra functional acrylate X x x IRR 784 Aminated Polyether Acrylate x x IRR 778 Chlorine Free Diluted Polyester X x EBECRYL 220 Hexafunctional Urethane Acrylate X x EBECRYL 437 Diluted Polyester X x EBECRYL 570 Chlorine Free Polyester x SELF-CURING RESINS FOR PHOTOINITIATOR-FREE SYSTEMS The migration of low molecular weight photoiniators is also an issue with UV cured systems for food packaging applications. While higher molecular weight polymeric photoinitiators have helped to decrease the migration risk, they are often difficult to solubilize in acrylates. Allnex has therefore, to further extend the EBECRYL LEO product line, taken the approach of developing a self-curing acrylate resin for the formulation of UV curable inks and varnishes that eliminates the need for a photoinitiator. The self-curing acrylate resin is currently undergoing beta testing in the E.U. and U.S. The new self-curing resin is polymeric. It exhibits high reactivity and its viscosity is acceptable for most UV Flexo and overprint varnish applications. Adaptations are still being made for UV Lithography applications. The raw materials used are of very high purity, thus avoiding low molecular weight impurities that are prone to migration. The process for making the self-curing resin was also optimized to avoid any residual contaminants. Notably, the resin has the ability to generate free radicals upon UV irradiation and does not produce any unwanted byproducts during this process. In addition, acrylate functionalities are incorporated into the oligomer and react when the resin is cured, binding the resin into the matrix of the film, thus further reducing the risk of migration. Initial studies of the new self-curing acrylate resin in various formulations have demonstrated that it is suitable for use in inks with different types of pigments using different types of application techniques. BISPHENOL A BACKGROUND Epoxy acrylate oligomers are widely used in energy cured coatings for wood, metal and plastics, overprint varnishes (OPVs), and lithographic and silk screen inks because they offer a good balance between performance and cost. Films based on epoxy acrylates cure rapidly, have high gloss and high hardness, and offer good chemical, water, corrosion and scratch resistance. They also can help decrease the cost of coating and ink formulations. Bisphenol A diglycidyl ether (BADGE) is one of the key monomers used in the preparation of epoxy acrylate oligomers, and this monomer is derived from BPA. While most studies to date have generally indicated that the current levels at which humans are exposed to BPA are safe, recent results obtained using new methodologies have raised some concerns about the possible effects that BPA may have on the health of the very young. The US Food and Drug Administration (FDA) has initiated additional studies to determine what, if any, regulatory actions it should take with respect to BPA in food contact applications. In Europe,

4 BPA is also permitted for use in food contact materials, but the human risks associated with exposure to BPA through the diet are being re-evaluated. Canada declared BPA a toxic substance in BPA-FREE ALTERNATIVES There are some bisphenol A-free alternative chemistries available on the market for use in packaging and graphic arts applications, including aliphatic and aromatic urethane acrylates, polyester acrylates, and acrylated bio-based building blocks. Urethane acrylate oligomers offer a good balance between flexibility, hardness, and chemical and abrasion resistance. They suffer, however, from high viscosity and high cost. Polyester acrylate oligomers are resistant to yellowing and are lower in viscosity, but can be moisture sensitive. Acrylated polyols derived from soybean and other natural oils are attractive for their bio-based content and pigment wetting properties, but have solvency issues and form ink and coating systems that often are too soft. APPLYING THE HOLISTIC APPROACH TO BPA Eliminating BPA-containing products used in UV/EB energy cured inks and coatings would probably be a major performance challenge and depending on the application along with established widespread customer and regulatory adoptions, a difficult task. Bisphenol A imparts ideal properties (hardness and resistance) to both inks and coatings, and it does so cost-effectively. Food Contact Notification (FCN) 772 received FDA clearance on March 8, Specifically, FCN 772 clears for direct food contact any mixture of one or more of tripropylene glycol diacrylate (TPGDA), trimethylolpropane triacrylate (TMPTA), trimethylolpropane ethoxylate triacrylate (TMPEOTA), and epoxy diacrylates such as EBECRYL Therefore, finding alternative building blocks with the same set of costs, performance attributes and regulatory status is no easy task. To achieve this goal, Allnex first focused on the properties of bisphenol A and BPA diglycidyl ether that contribute to the final, desirable performance properties observed in UV cured films derived from these raw materials. At the same time, taking into consideration current and future market needs, a bio-based solution was highly desired in order to address the need for alternatives to petrochemical-based products throughout the ink and coatings value chain. THE POTENTIAL OF GLUCITOL Glucitol is a non-aromatic, bio-based building block produced commercially. It is a naturally occurring sugar found in wheat and corn, and is experiencing growing demand in the plastics industry and thus is a relatively inexpensive raw material. Glucitol is commercially available from industrial suppliers in the U.S., France, India and China. It is estimated that the current global production capacity of glucitol for industrial applications is over five thousand metric tons per annum with additional capacity coming online annually. USP grades of glucitol have been used in a variety of medical treatments over the past forty years. Studies in the plastic industry have indicated that glucitol exhibits properties similar to BPA when used in plastic formulations. Glucitol has also been investigated in polyester, polyurethane and epoxy thermoset applications. The rigid structure of glucitol is expected to impart attractive properties to cured systems, while its low molecular weight can enable lower-viscosity resin formulations that are easier to apply. The potential for various glucitol derivatives to serve as BPA replacements in UV cured inks and coatings was thus explored. 2 Further information regarding the U.S. FDA Food Contact Notification 772 can be found on the RadTech International North America website at

5 INITIAL INVESTIGATIONS A series of glucitol-based experimental acrylates containing greater than 50% renewable content and with different ratios of glucitol and acrylic acid were formulated with photoinitiators and diluents and adapted to produce BPA-free systems. Typical properties for acrylated glucitol (AG) and its cured films are presented in Tables 3 and 4, respectively. Performance properties for AG as a formulated coating can be seen in Tables 5 and 6. Its performance in an overprint varnish (Table 7) and a Flexographic ink (Table 8) is also compared to other chemistries commonly used for the same respective applications. Table 3. Typical properties of acrylated glucitol Dynamic viscosity ± 450 mpa.s at 25 C Density 1.26 g/cm 3 Colour max 1 Gardner Table 4. Typical cured properties for films based on AG and other acrylates* Properties AG EBECRYL 600 EBECRYL 130 EBECRYL 220 Tensile strength (MPa) (**) Tensile elongation (%) (**) <1 4 2 <2 Young s Modulus, (MPa) (**) Tg (by DMTA- max tan δ) ( C) Shrinkage (%) (***) *EBECRYL 600 is a di functional epoxy acrylate; EBECRYL 130 is a cyclic aliphatic diacrylate; EBECRYL 220 is a hexafunctional aromatic urethane acrylate. (**) Measured on a 80µ EB cured film. Measurement methods: Tg (by DMTA- max tg δ): ASTM E ;Tensile strength, Tensile elongation, Young s Modulus: ASTM D638-61T and ISO 527-1; (***) Shrinkage: estimated from the density change between the liquid and the cured solid state The potential utility and performance of the experimental glucitol formulations in energy cured inks, overprint varnishes and coatings were evaluated by comparing their performance with EBECRYL BPA-based and EBECRYL BPA-free energy curable systems. AG performance results are presented below. First, the performance of an AG-based coating was compared to that of a coating based on BPA epoxy acrylate EBECRYL 605, which contains 25% tripropylene glycol diacrylate (TPGDA). Results are presented in Table 5. It should first be noted that the viscosity of AG was much lower than that of the formulation based on the BPA-derived resin. In addition, the minimum cure dose (mj/cm²) was lowest for the AG systems. The hardness and mechanical properties of the AG-based coatings (with varying degrees of glucitol acrylation) were similar to the BPA-based coating formulations tested. Coatings prepared from blends of AG with other resins, such as other polyester acrylates, urethane acrylates, and polyesters, also exhibited enhanced cure speeds and mechanical properties when compared to the performance of similar blends using another cycloaliphatic diacrylates.

6 Table 5: Comparison of the properties of AG and BPA-based coatings Component AG EB 605 AG 100 EBECRYL TPGDA 30 Additol BCPK 5 5 TPGDA % Viscosity 25 C Min cure dose ( mj/cm² ) Pendulum Hardness ( sec ) Youngs modulus ( MPa ) Elongation ( % ) Curing Conditions: - 10µ on white paper - curing with 80W UV lamp. (Source: Collette Moulaert Allnex TS&D) Next, the performance of an AG-based hardcoat formulation on plastic was compared to that of a hardcoat formulation based on the top-performing resins EBECRYL 1290 and EBECRYL 810. EBECRYL 1290 is an aliphatic urethane hexa-acrylate and was selected for comparison against AG for its fast cure, high hardness and solvent resistance. EBECRYL 810 is a polyester tetra-acrylate and was chosen for its low viscosity, hardness, chemical resistance and adhesion. The results are present in Table 6. Table 6. Comparison of AG and EBECRYL-based hardcoat formulations on plastic EBECRYL 1290 EBECRYL 810 AG viscosity mpa.s 25 C aspect: on Leneta paper ok ok ok on PC sheet ok ok ok CHA(0=good, 5=bad) Pencil hardness 2B 3B 3B Stains (1=bad,5=good) coffee (4%,16h) mustard (16h) N70 black marker (xh) DR Steel wool (5=good, 1=bad) on Leneta paper on PC sheet DR Steel wool on Leneta paper on PC sheet Taber haze 100 cycles sample sample cycles sample sample The resins were diluted 30% in hexanediol diacrylate and formulated with Additol CPK as the photoinitiator and Modaflow 9200 for flow and leveling. The coatings were cured at 10 m/min with a 120 W/cm Hg lamp at a coating weight of10 g/cm² on a 250 micron polycarbonate sheet. As can be seen in the table, the AG formulation again had a much lower viscosity than the EBECRYL-based systems. Taber haze abrasion resistance was best (100 & 500 cycles)

7 with AG (Figure 1). The steel wool resistance and pencil hardness were, however, slightly lower for the AG-based hardcoat. It was also determined using LENETA charts (data not shown) that the AG-based coating was less yellowing than the EBECRYL-based hardcoat. Figure 1. GLUCITOL-BASED CHEMISTRY IN OVERPRINT VARNISH APPLICATIONS The performance of an AG-based overprint varnish (OPV-3) was compared with that of EBECRYL 6040 (OPV-1) and EBECRYL 605 (OPV-2) formulations (Table 7). It should be noted that the AG-based OPV contained 45% renewable raw materials. Table 7. OPV formulations containing AG and epoxy acrylates OPV 1 OPV 2 OPV 3 EBECRYL EBECRYL AG 80 EBECRYL TPGDA EBECRYL Esacure HB* * Esacure HB: 50/50 mixture of benzophenone/hydroxy cyclohexyl phenone sold by Lamberti; OPV viscosity: 500 mpa.s (+/- 20 mpa.s) at 25 C EBECRYL 6040 is a modified bisphenol-a epoxy acrylate with low viscosity, high scratch resistance and gloss and good solvent resistance. EBECRYL 605 is a di-functional epoxy acrylate based on BADGE and contains 25% TPGDA. Compared to the epoxy acrylate systems tested, AG exhibited improved surface cure (Figure 2) and superior solvent resistance as measured using acetone double rubs (Figure 3). Overprint varnishes were applied to 3nt-4 regular bond natural white coated Leneta.

8 Figure 2. Improved surface cure (120 W/cm) of an AG-based OPV ink 60 Line Speed (Meters/Min.) EBECRYL 6040 EBECRYL 605 Acrylated Glucitol OPV-1 OPV-2 OPV-3 Figure 3. Superior solvent resistance (120 W/cm) of an AG-based OPV ink GLUCITOL-BASED CHEMISTRY IN LITHOGRAPHIC APPLICATIONS The performance of AG was then evaluated against EBECRYL 657, which is a polyester acrylate commonly used in UV offset applications. EBECRYL 870 was added to the AG at a 20% ratio in order to boost AG s overall viscosity so that it could be used on a triple roll mill and to assist with pigment wetting. EBECRYL 870 is a polyester hexa-acrylate with high reactivity and very good lithographic behavior and pigment wetting. AG/870 pigment dispersions were made using Clariant process color pigments (PY13 Permanent Yellow GR, PR57:1 Permanent Rubine L5B-01 and PB15:3 PV Fast Blue BG) in a three roll mill. The AG/870-based resin system was, however, kicked out of all of the pigment preparations after three mill passes. Overall, AG/870 dispersions exhibited poor pigment wetting and poor lithographic performance properties. It is believed, however, that AG could be used as a diluent for monomer-free ink formulations. More testing must be completed in order to prove out AG s potential as a diluent for lithographic applications. All

9 AG UV Litho testing was completed at the graphic arts application laboratory of Clariant Corporation in Charlotte, NC. GLUCITOL-BASED CHEMISTRY IN FLEXOGRAPHIC APPLICATIONS The performance of AG was then compared in a 60/40 blend with EBECRYL 870 against the modified epoxy acrylate EBECRYL 3203 in black Flexographic inks (Table 8). Special Black 250 (Degussa) was used as the base pigment. Properties tested included rheology at 25 C, optical density, gloss and surface cure. The fully formulated AG/870 black ink was found to be slightly more Newtonian than EBECRYL Under curing at 120 W/cm and 70 m/min, the AG/870 formulation exhibited a comparable surface cure and optical density and a higher gloss than that measured for the EBECRYL 3203-based black ink. It should be noted that the black Flexo formulation based on AG contained 30% renewable raw materials. Table 8. Formulation and properties of black Flexo inks containing AG and EBECRYL 3203 REFERENCE EBECRYL EBECRYL AG 15.3 Stabilizer solution Solsperse (Lubrizol) Black pigment (Special Black 250) AG 34 DPHA 10 EBECRYL EBECRYL Ethyl-4-dimethyl amino benzoate 5 5 Phenyl benzophenone 3 3 Irgacure 369 (BASF) 1 1 Viscosity at 2.5 s-1 25 C Viscosity at s Shortness Index Flow after 30 sec (cm) Optical Density at 1.2 g/m² Gloss 60 at 1.2 g/m² Cure speed 120W/cm - m/min Inks were applied to 3nt-4 regular bond natural white coated Leneta. AG-Based Due to its initial promising performance in UV Flexo, AG testing was then continued at the graphic arts application laboratory of Clariant Corporation in Charlotte, NC. EBECRYL 812, a polyester tetra-acrylate was selected as a comparative reference because of its low viscosity and common usage in UV Flexo inks (Table 9). Table 9. Dispersion and ink formulations for Flexo with AG and EBECRYL 870 Pigment Dispersion for Flexo Application AG Ink Formulation for Flexo Application Ingredient % Manufacturer Ingredient % Manufacturer NPG Monomer 58 Allnex Dispersion 50 Solsperse Lubrizol AG or EBECRYL Allnex Solsperse Lubrizol Photoinitiator 10 BASF (for yellow only) Florstab UV-1 2,0 Kromachem Isopropryl Alcohol % (optional) Pigment* 30 Clariant *Clariant pigments used for Flexo formulation testing with AG and EBECRYL 870 included: PY14 Permanent Yellow GSO, PR57:1 Permanent Rubine P-L5B-01 and PB15:4 Hostaperm Blue BT-617-D.

10 Compared with EBECRYL 812, AG was found to be suitable as a Flexo pigment dispersion letdown oligomer. It has a very stable viscosity (Figure 4) and minimal shear thinning properties. At less than 200 mpas, the AG-based inks exhibited performance properties that fell in the range of waterborne Flexo ink systems when applied to 3nt-4 regular bond natural white coated Leneta. An excellent cure response was also observed for the AG-based ink formulation. Cured gloss with all pigments remained very high. On the 400 line anilox, AG delivered color densities very close to pantone yellow, rubine and blue. However, AG s stability in rubine-based pigments appears to be sensitive after 24 hours. AG stability testing with rubine-based pigments is currently underway in order to determine what might be causing the shear viscosity increase over time and after 24 hours. Figure 4. Viscosity stability of Flexo ink formulations based on AG

11 POSTIVE OUTLOOK FOR GLUCITOL In general, the initial performance results obtained for various coatings and Flexo ink systems based on glucitol chemistry are very encouraging. Clearly, glucitol has the potential to serve as an important renewable raw material in a variety of energy curable ink, overprint varnish and coating applications. The demonstrated low viscosity and high reactivity performance characteristics of the high-performing bio-based AG suggest that it may not only be a suitable replacement for BPA-containing epoxy acrylates, but it may also find use in a variety of other ink and coating applications as well. Further studies are underway to determine AG s performance in UV inkjet and UV gravure applications, where its low viscosity, shear stability and high reactivity, coupled with its capacity for building reduced diluent content inks, are of great interest in a variety of consumer product packaging and graphic art applications. CONCLUSIONS The consumer product packaging and graphic arts industries are facing numerous challenges with respect to the need to eliminate possible chemicals of concern. Advances in energy curing technology from Allnex are helping overcome these key challenges in printing and coating applications. Our EBECRYL LEO and expanding line of low migration resins for food packaging applications are helping customers meet increasing regulatory requirements. Further expansions are planned for the Non-GMP product line for Flexo, Litho and OPV applications with solutions containing high levels of renewable content, reflecting our recognition of the value that bio-based materials brings to the market. With new BPA-free resin technology based on renewable raw materials, customers in various market segments will also be prepared to replace BPA-containing formulations with high-performing alternatives. These new forward-looking technologies are just some of the energy cured resin solutions that Allnex is developing that both provide high performance, cost savings and anticipate future changes in ingredient expectations. Notice: Trademarks indicated with the, or * are registered, unregistered or pending trademarks of Allnex Belgium SA or its directly or indirectly affiliated Allnex Group companies. Disclaimer: Allnex Group companies ( Allnex ) decline any liability with respect to the use made by anyone of the information contained herein. The information contained herein represents Allnex's best knowledge thereon without constituting any express or implied guarantee or warranty of any kind (including, but not limited to, regarding the accuracy, the completeness or relevance of the data set out herein). Nothing contained herein shall be construed as conferring any license or right under any patent or other intellectual property rights of Allnex or of any third party. The information relating to the products is given for information purposes only. No guarantee or warranty is provided that the product and/or information is adapted for any specific use, performance or result and that product and/or information do not infringe any Allnex and/or third party intellectual property rights. The user should perform its own tests to determine the suitability for a particular purpose. The final choice of use of a product and/or information as well as the investigation of any possible violation of intellectual property rights of Allnex and/or third parties remains the sole responsibility of the user Allnex Group. All Rights Reserved.