Progress 07/01/17 to 02/28/18
Outputs
Target Audience:Isosorbide-based epoxies are promising candidates for replacement of bisphenol A diglycidyl ether (BADGE) for a variety of industrial and biomedical applications. Isosorbide is a rigid organic diol derived from glucose, thereby making it a viable bio-based alternative to traditional fossil fuel based chemicals. While crosslinked isosorbide diglycidyl ether absorbs too much water to be useful in applications such as can coatings, hydrophobic modifications have been demonstrated to reduce water absorption to acceptable levels for such applications. Isosorbide 2,5-(glycidyloxybenzoate)s (IsoBGB) substituted in the ortho-, meta- and para- positions will be evaluated as part of this work for their feasibility as can coatings as a replacement for BADGE. Particular advantages of the bio-based epoxies include not being derived from petroleum resources and not being estrogen mimetics like bisphenol A 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?Emphasis will be placed on optimization of reaction conditions for the two-step synthesis procedures to demonstrate the economic viability of Iso2BGB as a replacement for BADGE in food and beverage can coatings. A 100 gram batch of isosorbide 2,5-(3-glycidyloxybenzoate) (Iso3BGB) will be provided to Vuronyx for coating experiments to evaluate its technical feasibility. Additional tests for flexibility, blush resistance and mechanical properties will be conducted and additives incorporated into the formulations to enhance their performance. Initial test of biocompatibility will also be performed.
Impacts
What was accomplished under these goals?
Synthesis A 120 gram batch of isosorbide 2,5-(2-glycidyloxybenzoate) (Iso2BGB) was synthesized according to the procedure developed at NJIT.The purity of Iso2BGB is approximately 92% by weight (by NMR). Residual solvent peaks for acetone (2.08 ppm) and toluene (2.30 and 7.14 ppm) are evident, as well as a broad signal between 0.5 and 2 ppm corresponding to the 22 protons of dicyclohexyl urea. Work has also been conducted to explore more economically viable synthesis procedures. These fall into two categories: the first being modification of the existing procedure to reduce cost and the second being development of an alternative route, ideally involving only two steps. Key results of the initial experiments are described as follows. Allyl chloride is much less reactive than allyl bromide toward hydroxybenzoic acids. Elevated temperatures need to be explored to get this reaction to go in reasonable time and yield. Allyl chloride is desirable as a reagent because it is significantly cheaper than allyl bromide on a large scale. Allyl bromide reacts readily with hydroxybenzoic acids at room temperature in the presence of anhydrous potassium carbonate. The addition of 18-crown-6, a potassium coordinating phase transfer catalyst, appears to increase the reaction rate modestly. Synthesis of isosorbide bis(4-hydroxybenzoate) has been demonstrated according to US Patent Application 20020013483 issued to L. Brader, et al.. However, in two tries, the yields have not been reproduced and the product is difficult to purify. The method of Bader, et al. was applied to making isosorbide 2,5-bis(3-allyloxybenzoate) with modifications from isosorbide and 3-allyloxybenzoic acid. Cyclohexane was substituted for toluene as the azeotroping solvent because it effectively removes water at a lower temperature. p-Toluenesulfonic acid was substituted for sulfuric acid as the catalyst. No water was removed from the reaction. Addition of sulfuric acid to the reaction mixture appears to be liberating some water. The higher temperature of the toluene azeotrope (84 °C vs 70 °C) may also be required to drive the reaction. This experiment is in progress. Coating Experiments Two controls were used for the coating experiments. BADGE (Epon 828, Hexion) with an epoxide equivalent weight of 190 g/eq was selected as an unformulated epoxy resin that would allow for baseline comparison with Iso2BGB. MAX CLR epoxy resin (Polymer Composites, Inc.) was chosen as the formulated control because it is FDA compliant for direct food contact and is compositionally similar to patented can coatings [TDS, patents]. The aluminum used for the test panels was 5052-H32, which is typically used for beverage can ends. The test panels were purchased cut to a size of 4.5" wide by 10" long by 0.02" thick from onlinemetals.com. Three test panels were coated for each composition. Table 1: Curing schedules for the tested compositions. Ancamide 2353 Jeffamine T403 Mas CLR B Max CLR A N/A N/A 6 hours at 80°C BADGE 6 hours at 80°C 4 hours at 80°C, 3 hours at 120°C N/A Iso2BGB 6 hours at 80°C 4 hours at 80°C, 3 hours at 120°C N/A The Iso2BGB/Ancamide 2353 composition appeared to phase segregate at room temperature during application to the aluminum panels. Additionally, after curing it was evident from inhomogenous color of the coatings that phase segregation had still occurred, regardless of the mixing temperature. BADGE was entirely miscible with Ancamide 2353 and no phase segregation was observed. Both BADGE and Iso2BGB coatings cured with Ancamide 2353 were brittle and fractured on bending a test piece into a U shape. As a result of this discrepancy, Ancamide 2353 was abandoned as a curing agent. Coating Thickness Measurement Coating thickness was measured using a coating thickness gauge made by Yuwese. The reported coating thickness is the average of 5 measurements taken in a marked vicinity on the coated test panel. Thickness (mm) +/- Standard Deviation Max CLR A/B 29.8 +/- 10.4 BADGE/Jeffamine T403 59.8 +/- 8.9 BADGE/Jeffamine T403/BYK 3440 76.2 +/-7.0 Iso2BGB/Jeffamine T403 107.4 +/- 31.3 Iso2BGB/Jeffamine T403/BYK 3440 97.5 +/- 24.0 Coating Adhesion Testing Adhesion testing on the coated aluminum panels was performed according to ASTM D3359. Because the average coating thickness for most test panels was 50 μm or greater, the cross-hatch adhesion test was conducted.The average score for the nine test areas (3 test areas on 3 panels) is reported in Table 2. Table 2: Adhesion test scores for Max CLR, BADGE and Iso2BGB coatings. Adhesion Test Score Max CLR A/B 6.67 +/- 2.18 BADGE/Jeffamine T403 7.58 +/- 2.24 BADGE/Jeffamine T403/BYK 3440 7.87 +/- 2.16 Iso2BGB/Jeffamine T403 10.0 +/- 0.0 Iso2BGB/Jeffamine T403/BYK 3440 6.34 +/- 4.33 Pencil Hardness Test The pencil hardness test was conducted with a tester and pencils purchased from BYK-Gardner. The pencils range in hardness from 9B (softest) to 9H (hardest). The results of the pencil hardness test for BADGE and Iso2BGB coatings with Jeffamine T403 as crosslinker and Max CLR are reported in Table 3. ?Table 3: Results of Pencil Hardness Test for Max CLR, BADGE and Iso2BGB coatings. Pencil Hardness Score Max CLR A/B 2H, 7H, 3H BADGE/Jeffamine T403 6H, 7H, 6H BADGE/Jeffamine T403/BYK 3440 7H, 6H, 6H Iso2BGB/Jeffamine T403 7H, 7H, 7H Iso2BGB/Jeffamine T403/BYK 3440 3H, 2H, 2H ?Use of Solvents or Reactive Diluents to Reduce Viscosity of Epoxy Coating and Provide Uniform Thickness Four different solvents and one reactive diluent were selected for these experiments. The overall goal is to reduce the viscosity of the coating, as it is hypothesized that this will reduce the coating thickness and enhance the uniformity. Comparison of these compositions with the compositions containing only epoxy and crosslinker will also be conducted to determine how the other properties of the coating are affected. The solvents were chosen for their miscibility with isosorbide 2,5-(glycidyloxybenzoate) (Iso2BGB) and the crosslinker, Jeffamine T403, as well as the range of boiling points covered. Three conditions were tested to determine how solvent evaporation might affect coating uniformity. One set of coated panels was left at 20°C overnight, another was placed in a vacuum oven at 20°C overnight, and the last was heated at 80°C for 4 hours, as was done in the initial curing experiments. Compositions worth pursuing will be subjected to further evaluation for adhesion, solvent resistance, blush resistance and flexibility. The qualitative results of these experiments are summarized in Table 4. Table 4: Qualitative Observations on Coating Uniformity with Tested Solvents and Reactive Diluents. Solvent or Reactive Diluent 20°C Vacuum, 20°C Heat Cure Acetone bad poor poor Methylene Chloride fair fair - Toluene poor fair bad Benzyl Alcohol good - good n-Butyl Glycidyl Ether excellent - excellent The thickness of the coating on each panel was tested 5 times on the most uniform part of the coating using a coating thickness gauge made by Yuwese. The choice to test only the most uniform area of the coating was made because subsequent testing would use this area only, in order to generate accurate and comparable results. The thickness measurements are presented in Table 5. Table 5: Thickness Measurements for Coatings with Tested Solvents and Reactive Diluents. Panel Number 1 2 3 4 5 Average Thickness (µm) St. Dev. GB01/14 21.2 19.8 40.6 54.1 42.4 35.6 13.2 GB01/14 42.4 29.5 10.6 11.7 11.7 21.2 12.7 GB01/15 8.2 1.3 0.7 2.0 3.3 3.1 2.7 GB01/15 6.0 4.6 3.3 2.0 3.3 3.8 1.4 GB01/16 13.0 14.4 12.0 9.5 8.2 11.4 2.3 GB01/17 69.8 52.8 61.4 69.1 78.6 66.3 8.7 GB01/17 64.0 51.1 52.6 52.9 54.4 55.0 4.6 GB01/18 30.5 33.1 34.6 33.1 34.1 33.1 1.4 GB01/18 41.4 40.1 41.6 38.9 37.4 39.9 1.6
Publications
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Progress 07/01/17 to 02/28/18
Outputs
Target Audience:We had conversations with can coaters and coating formulators. Can coaters such as Ball Corp and Crown Holdings expressed substantial interest, and guided us on the next steps for research and development. Coating formulators such as Sherwin Williams and PPG are also interested in licensing or collaborative agreement once we complete animal tests. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Apart from technical learnings for full time employers of Vuronyx on this project, it also provided an opportunity for a student from University of Massachussetts Amherst to work as an intern under the mentorship of the PI of this project. How have the results been disseminated to communities of interest?Based on Phase 1 work, we have filed a provisional patent. We do not plan to publish the coating performance testing data, but we will publish invitro and invivo testing data obtained in Phase 2. 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 1 SBIR project, Vuronyx Technologies developedIsoKote Coatings - the first BPA free, high performance epoxy based can coatings for food and beverage applications. The non-estrogenic and excellent mechanical properties of IsoKote coatings have generated wide interest amongst the coating companies, brand owners and can coaters, who are now looking to partner with us for further development and commercialization. Canned foods and beverages is an important part of the global food supply chain. Consumers expect canned foods and beverages to maintain their freshness, flavor, and nutritional value, and be free of contamination by pathogens. In food and beverage industry, these set of goals are accomplished by providing a protective coating of epoxy polymer resin on metal cans. Currently used coatings for food and beverage cans are based on Bisphenol A diglycidyl ether (BADGE), which leeches Bisphenol A (BPA) into the food/beverage product. There has been recent public awareness of BPA being linked to a long list of deleterious effects including cancer, reproductive abnormalities and infertility, metabolic disorder including diabetes, obesity, and attention deficit/hyperactivity disorder (ADHD).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. Our approach is based on replacing BPA based epoxy with isosorbide based epoxy. Isosorbide is a cheap biobased precursor material made by dehydrating sorbitol which is a polyhydric alcohol derived by reduction of glucose. Roquetterecently launched world's largest isosorbide production facility of 20,000 tons/year, and have plans for further capacity expansion. The rigid structures and special molecular geometry make isosorbide a good candidate to replace BPA without the endocrine disrupting effect. Isosorbide can serve as renewable building blocks for many applications including thermoplastics, thermosets and specialty chemicals.Our results in Phase 1 demonstrate the adhesion, chemical resistance, and mechanical properties of isosorbide epoxies is comparable or better than BPA epoxies, thus providing a pathway for completely eliminating a endocrine disrupting chemical from food chain, and aslo providing an application for isosorbide, abiobased molecule. In Phase 1, we investigated coatings of IsoBGB based epoxy on aluminum panels and characterized coating properties. BPA based epoxy was used as control. Initial formulations were made with IsoBGB dissolved in a solvent, with and without adhesion promoters. The coatings were performed by doctor blading.The overall target of Phase 1 was to demonstrate that isosorbide based epoxy coatings have comparable properties to BPA based epoxy coatings. Additionally, we also investigated approaches for low cost synthesis of with isosorbide bis(2-glycidyl benzoate), also called as Iso2BGB, using a one pot synthesis. The first objective in Phase 1 was synthesis of IsoBGB at 100 g scale. In Phase 1, we developed a one pot synthesis approach for IsoBGB for low cost manufacturing of the epoxies at 100 gram scale.Previous approach to synthesize IsoBGB from isosorbide used a four step reaction. In Phase 1, we investigated approaches for a two step and a step reaction to synthesize Iso2BGB. Both these approaches yields of IsoBGB at >90%, and therefore allow for low cost manufacturing of IsoBGB at large scales. The second objective was to perform coating withIsoBGB epoxy formulations.Two controls were used for the coating experiments. BADGE (Epon 828, Hexion) with an epoxide equivalent weight of 190 g/eq was selected as an unformulated epoxy resin that would allow for baseline comparison with Iso2BGB. MAX CLR epoxy resin (Polymer Composites, Inc.) was chosen as the formulated control because it is FDA compliant for direct food contact and is compositionally similar to patented can coatings. The aluminum used for the test panels was 5052-H32, which is typically used for beverage can ends.Initial coating experiments were performed by mixing a stoichiometric ratio of epoxy resin and hardener for about 5 minutes at room temperature then applying the mixture to aluminum panels with a drawdown bar. The BADGE and IsoBGB based coatings were formulated with and without BYK 3440 as a wetting agent. The Iso2BGB/Ancamide 2353 composition appeared to phase segregate at room temperature during application to the aluminum panels. This could be fixed slightly by mixing at 80°C for a few minutes, but dramatically reduced the workable time before the mixture gelled and could not be drawn effectively. Additionally, after curing it was evident from inhomogenous color of the coatings that phase segregation had still occurred, regardless of the mixing temperature. BADGE was entirely miscible with Ancamide 2353 and no phase segregation was observed. Both BADGE and Iso2BGB coatings cured with Ancamide 2353 were brittle and fractured on bending a test piece into a U shape. As a result of this discrepancy, Ancamide 2353 was abandoned as a curing agent after the initial round of experiments. For the other formulations, the testing thickness was 30-100 microns without solvents, and 40-60 microns for coatings diluted with solvents. For the third objective, we performed various tests on coated coupons. The first set of tests were conducted with formulations that had no solvents. Adhesion testing on the coated aluminum panels was performed according to ASTM D3359. Because the average coating thickness for most test panels was 50 μm or greater, the cross-hatch adhesion test was conducted.Iso2BGB (10.0 +/- 0.0) had better performance than either Max CLR (6.67 +/- 2.18) or BADGE (7.58 +/- 2.24) formulations.The pencil hardness test was conducted with a tester and pencils purchased from BYK-Gardner.Again, results of IsoBGB formulation were better than those of Max CLR or BADGE formulations. In the second round of testing, we investigated various solvents to reduce the viscosity, and obtain consistent coating thickness.Four different solvents and one reactive diluent were selected for these experiments. The overall goal is to reduce the viscosity of the coating, as it was hypothesized that this will reduce the coating thickness and enhance the coating uniformity. Comparison of these compositions with the compositions containing only epoxy and crosslinker were also conducted to determine how the other properties of the coating are affected. The solvents were chosen for their miscibility with isosorbide 2,5-(2-glycidyloxybenzoate) (Iso2BGB) and the crosslinker, Jeffamine T403, as well as the range of boiling points covered.The best results were obtained with benzyl alcohol and n-butyl glycidyl ether, which were then selected for further tests. Various tests were then performed on coupons coated with diluted epoxy formulations.Excellent results were obtained with Iso2BGB containing 5% solvent or reactive diluent.Samples of each composition were subjected to cylindrical mandrel bend test for flexibility.The BADGE coatings and Iso2BGB coatings with n-butyl glycidyl ether did not crack at the smallest mandrel size (0.25") which demonstrates coating flexibility.Acid and detergent resistance tests were also performed for each formulation. For each test the bottom 1-2" of each coated panel is submerged in the test solution for 10 minutes. The JOY detergent test uses a 1% aqueous solution of JOY detergent. The acid resistance test uses a 30% aqueous phosphoric acid solution. All samples tested, except IsoBGB with benzyl alcohol, showed complete resistance to detergent and acid solutions as evidenced by their lack of visible changes. Overall, we successfully completed the three objectives of Phase 1. Further we demonstrated the isosorbide based epoxies have comparable or better performance than BPA epoxies, thus opening their use for food and beverage applications.
Publications
- Type:
Other
Status:
Submitted
Year Published:
2018
Citation:
US Provisional Application 62639763, "Isosorbide based epoxy formulation"
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