Progress 09/01/18 to 02/28/21

Outputs
Target Audience:In this Phase II SBIR project, Vuronyx Technologies investigated high performance BPA free epoxy coatings for food and beverage cans. Canning of foods and beverages in metal containers is extensively used for food preservation and storage. The protective coating applied on the inside surface of the food/beverage container should be safe for food contact, have excellent adhesion to the substrate, and resist degradation over long periods of time. Currently used coatings for food and beverage cans are based on Bisphenol A (BPA). BPA present in epoxy coatings in cans have been found to leech into food products, and there is a positive correlation between consumption of canned foods and beverages and their presence in human urine and blood. The health hazards of Endocrine Disrupting Chemicals (EDCs), such as BPA, are well-established - including cancer, brain and behavioral changes in fetuses, and female reproductive issues. The BPA-free epoxy coating developed by Vuronyx Technologies is non-estrogenic but will still provide similar or improved barrier performance. The coatings are derived form isosorbide, an inexpensive biobased precursor material made by dehydration and reduction of glucose. Successful commercialization of these new coatings will encourage large-scale synthesis of the biobased epoxy precursors. In Phase II project, Vuronyx Technologies formulated the coatings and test their barrier properties and mechanical performance in food and beverage cans. Further, the toxicological performance of these new coatings were conducted both invitro and in-vivo, and compared to currently used BPA based epoxy coatings. Based on our Phase II results, we have established that the new biobased coatings have non-estrogeic properties, and have similar barrier and mechanical performance. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? In Phase 2, we achieved the following goals: optimize synthesis of isosorbide compound complete the formulation of epoxy coatings in-vivo and in-vitro animal studies were performed with the isosorbide compound.

Publications

Progress 09/01/20 to 02/28/21

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? - Demonstrated with HPLC that our coatings do not leech major coating components Further optimized the coating composition Initiated discussion with Crown Holdings

Publications

Progress 09/01/19 to 08/31/20

Outputs
Target Audience:We contacted can coaters, including Crown Holdings, to evaluate our coatings for food and beverage cans. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?- Final formulation, characterization and toxicological studies

Impacts
What was accomplished under these goals? - We developed formulation using Iso2BGB - We compared performance of Iso2BGB coatings with respect to Bisphenol A Coatings - We conducted initialtoxicological studies

Publications

Progress 09/01/18 to 08/31/19

Outputs
Target Audience:We initiated discussions with can coaters on our epoxy coatings. Based on our results, they advised us on further tests that need to be performed. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?We hired an intern from University of Massachusetts, Lowell to help us with coatings development and formulation How have the results been disseminated to communities of interest?We have approached can coaters with our coating results, who have advised us to perform further specific tests on the coatings. What do you plan to do during the next reporting period to accomplish the goals? We have been making progress in the optimization of the synthesizing Iso2BGB significantly lower the production cost and improve the purity and yield of the product, which is the cornerstone of commercialization. We will work closely with the downstream team to scale up the synthesis process and initiate the preliminary evaluation of the cost. Two in vitro estrogenic test confirmed the non-estrogenic nature of Iso2BHB. We will continue to study the estrogenic behavior of Iso2BHB in animal study proposed before. Formulation of the Iso2BGB- based coating has been adjusted to give comparable or even better performance to the BADGE counterpart in adhesion, hardness and flexibility. The resistance tests, including the salt spray test, UV weathering test, water immersion test and resistance in various conditions are still in the process and the results will be expected in the next few months. Over the next year, we will perform toxicological studies with our optimized formulation as described in the Phase 2 proposal. Conclusion and Future work We have been making progress in the optimization of the synthesizing Iso2BGB significantly lower the production cost and improve the purity and yield of the product, which is the cornerstone of commercialization. We will work closely with the downstream team to scale up the synthesis process and initiate the preliminary evaluation of the cost. Two in vitro estrogenic test confirmed the non-estrogenic nature of Iso2BHB. We will continue to study the estrogenic behavior of Iso2BHB in animal study proposed before. Formulation of the Iso2BGB- based coating has been adjusted to give comparable or even better performance to the BADGE counterpart in adhesion, hardness and flexibility. The resistance tests, including the salt spray test, UV weathering test, water immersion test and resistance in various conditions are still in the process and the results will be expected in the next few months.

Impacts
What was accomplished under these goals? Optimization of Iso2BHB synthesis The condensation reaction between isosorbide and salicylic acid involves the elimination of water as the byproduct. Due the unreactive nature of secondary alcohol in isosorbide, it is crucial to effectively remove the byproduct to favor the generation of the product, shifting the equilibrium of esterification to the completion. Thus, a dean-stark apparatus and a lighter and water-immiscible organic solvent (density D < 1 g/mL), xylene, for example, were introduced into the reaction setup. During the reaction of refluxing, the lower density of xylene ensures trapping the byproduct in the Dean-stark apparatus during the condensation of azeotrope of water-xylene formed in the system. Catalyst selection In phase 1, we selected sulfuric acid as the sole catalyst for the esterification reaction because of its effectiveness and low-cost. However, the isosorbide is known to be unstable under oxidative environment at high temperature. After introducing the sulfuric acid in the system, some of the isosorbide got oxidized directly, which, as a result, contributed to the low yield of the product and complication of workup procedure. A non-oxidative acid catalyst turned out to be the key to resolve the issue. After exploration the pool of alternative catalysts, we laid our eyes on p-toluenesulfonic acid (PTSA). PTSA stood out as the most effective catalyst among other non-oxidative ones. Optimization of Iso2BGB synthesis In the phase 1, we demonstrated the possibility of direct epoxy synthesis from Iso2BHB with epichlorohydrin in N,N-dimethylformamide (DMF). Potassium carbonate was used to neutralize HCl generated during the reaction. However, the high boiling point of DMF made it difficult to be completely removed under rotary evaporator. Also, the thin-layer chromatography indicated a significant amount of impurities were generated during the reaction. A full-scope research was conducted to search for viable approach to produce Iso2BGB with high purity in a large scale. The alternative synthetic pathway with no solvent in the experimental section was found to yield higher with less byproduct generation. In vitro Estrogen Receptor Transactivation Assay All the diphenol chemicals were subject to the in vitro estrogenic test at 10 different concentrations from 0.5 nM to 10 µM. Among all the test chemicals, Iso2BHB was the only diphenol that the phenolic group located at the ortho position to the bridging group, in this case, the ester group. The estrogen displacement ratio remained below 25% even at the high concentration of 10 µM, fell into the non-estrogenic category (Figure b and b'). For the other three chemicals, Iso4BHB, BTF and TyDKP, with para-positioned phenolic alcohol, all showing an increasing displacement ratio to various degrees (figure c and c', d and d', and e and e', respectively). The non-estrogenic attribute of Iso2BHB was further confirmed by the E-screen assay using human breast cancer estrogen-sensitive MCF7 cells performed by Eurofins Panlabs, Inc. Both Iso2BHB (top) and Iso4BHB (bottom) were submitted for the test.The interaction between Iso2BHB and estrogen receptors (for both ER-α and ER-β) remained dormant (%Inh. below 5) throughout the entire experiment, with the concentration of up to 25 µM, whereas active displacements of Iso4BHB with estradiol were detected, especially for ER-β test. The double confirmation of non-toxicity of Iso2BHB laid the foundation of this project and allowed further research. Coating formulation and physical tests of Iso2BGB Based on the initial formulation from Phase 1, Jeffamine T-403 (polyoxypropylenetriamine) was pursued as the hardener due to its excellent curing performance and limited phase segregation. In this study, the molar ratio of diglycidyl ether and triamine will be adjusted to 6:1 and this stoichiometric ratio was chosen for all the formulations to obtain highly crosslinked rates. To reduce the high viscosity of Iso2BGB monomer and improve the uniformity of the coating, reactive diluent, 1,4-butanediol diglycidyl ether (BDDE), was selected. Comparing with the monoglycidyl ether, n-Butyl glycidyl ether (BGE), that we reported before, the difunctional diluent significantly enhanced the crosslinking features and reduced the plasticizing effect. Coating thickness was measured using a coating thickness gauge made by Yuwese. The coating thickness reported in Table 1 was the average of 10 measurements taken in a marked vicinity on the coated steel sheet. All coating samples were applied using 60 µm side of the bar applicator. Sample Composition Thickness (µm) +/- Standard Deviation Iso2BGB/BYK 307/BYK 4511/BDDE 55.3 +/- 8.2 BADGE/BYK 307/BYK 4511 78.1 +/- 13.2 Iso2BGB/BYK 307/BYK 4510/BDDE 59.8 +/- 11.2 BADGE/BYK 307/BYK 4510 69.2 +/- 10.8 Iso2BGB/BYK 333/BYK 4511/BDDE 69.9 +/- 5.2 BADGE/BYK 333/BYK 4511 51.2 +/- 8.6 Iso2BGB/BYK 333/BYK 4510/BDDE 63.4 +/- 7.8 BADGE/BYK 333/BYK 4510 66.8 +/- 8.8 Table 1. Results of Pencil hardness test for BADGE and Iso2BGB coatings with various formulations. Adhesion Test Adhesion test on steel substrates was performed according to ASTM D3359. Sample Composition Adhesion score Iso2BGB/BYK 307/BYK 4511/BDDE 4B, 4B, 4B BADGE/BYK 307/BYK 4511 4B, 4B, 4B Iso2BGB/BYK 307/BYK 4510/BDDE 5B, 5B, 5B BADGE/BYK 307/BYK 4510 5B, 5B, 5B Iso2BGB/BYK 333/BYK 4511/BDDE 4B, 4B, 4B BADGE/BYK 333/BYK 4511 4B, 4B, 4B Iso2BGB/BYK 333/BYK 4510/BDDE 5B, 5B, 5B BADGE/BYK 333/BYK 4510 5B, 5B, 5B Table 2. Results of Pencil hardness test for BADGE and Iso2BGB coatings with various formulations The results in Table 2 illustrated the same adhesiveness of Iso2BGB and BADGE coatings to the steel panel. A closer comparison indicated that, as adhesion promoters, BYK 4510 overall performed a grade better than BYK 4511 (5B vs 4B). The perfect adhesion score of Iso2BGB implies the great ability of protecting the substrate from corrosion, a critical property for epoxy resin. Pencil Hardness test Pencil hardness test is the evaluation method that performed to determine the hardness of a coating material. It was conducted with a mechanical holder and a spectrum of pencils (ranging from 9H to 9B in the Figure) from BYK -Gardner. Sample Composition Pencil Hardness Score Iso2BGB/BYK 307/BYK 4511/BDDE 3H, 3H, 4H BADGE/BYK 307/BYK 4511 HB, 1H, HB Iso2BGB/BYK 307/BYK 4510/BDDE 2H, 3H, 2H BADGE/BYK 307/BYK 4510 3H, 3H, 2H Iso2BGB/BYK 333/BYK 4511/BDDE 3H, 3H, 3H BADGE/BYK 333/BYK 4511 1H, 1H, 1H Iso2BGB/BYK 333/BYK 4510/BDDE 2H, 2H, 3H BADGE/BYK 333/BYK 4510 HB, HB, 1H Table 2. Results of Pencil hardness test for BADGE and Iso2BGB coatings with various formulations. Cylindrical Mandrel Bending Test The cylindrical Mandrel Bending Test examines the ability of an attached coating to withstand a material's deformation without failure. ASTM D522 standard test method B was followed, where the coated panels are bent over cylindrical mandrels of various diameters (ranging from 2 mm to 32 mm). Sample Composition Cylindrical Mandrel Bending Score (mm) Iso2BGB/BYK 307/BYK 4511/BDDE 2, 2, 2 BADGE/BYK 307/BYK 4511 8, 8, 8 Iso2BGB/BYK 307/BYK 4510/BDDE 2, 2, 2 BADGE/BYK 307/BYK 4510 6, 6, 8 Iso2BGB/BYK 333/BYK 4511/BDDE 2, 2, 2 BADGE/BYK 333/BYK 4511 8, 6, 6 Iso2BGB/BYK 333/BYK 4510/BDDE 2, 2, 2 BADGE/BYK 333/BYK 4510 6, 8, 8 Table 3. Results of Cylindrical Mandrel Bending Test for BADGE and Iso2BGB coatings with various formulations. All Iso2BGB-based coatings passed the smallest sized mandrel found in the standard kit (2 mm), whereas their BADGE counterparts barely passed 8 mm one. In theory, the increase in hardness is usually accompanied by brittleness or the decrease in flexibility of the coating. However, based on our results, the Iso2BGB-based coatings were superior in both hardness and flexibility than commercially available BADGE.

Publications