VOC-free Waterborne Epoxy Emulsions and Dispersions for Ambient Cure Coatings

1. VOC-free Waterborne Epoxy Emulsions and Dispersions for Ambient Cure Coatings

2. Waterborne Epoxy dispersions? • Stricter legislation is limiting the use of solvents-Volatile Organic Compounds (VOC) in paints e.g. • European directive 1999/13/EC and amendment 2004/42/EC • first stage implemented in 2007 • second stage implemented in 2010 • U.S.: 3 major organizations driving the reduction of VOC • Environmental Protection Agency (EPA, through Clean Air Act) • South Coast Air Quality Management District (SCAQMD) • Ozone Transportation Commission (OTC) • “Green Image” – environmental friendly coatings • Low odor, low flammability • Easy cleaning of equipment with water Making use of the excellent properties of Epoxy resins (e.g. corrosion resistance, chemical resistance, adhesion,…) with minimal amounts of solvent to fulfill legal and environmental requirements

3. Drivers and alternative approaches • Typical solvent borne formulations for Marine and Protective coatings are based on epoxy resin grades with an Epoxy Equivalent Weight of ~500 gr/eq containing solvents like Xylene • Typical solvent content of these solid epoxy resin solutions is 25% • Major contributor to the overall VOC content of a solvent borne formulation • Several approaches exist to minimize or eliminate the VOC content • High solids coatings • Powder coatings • Radiation cured coatings • Waterborne coatings

4. Dow’s Technology Approach Chemistry + • Dow technology • Non ionic surfactant was especially developed for WB epoxy resins • Surfactant is epoxy functional so that it will be part of the cured matrix • Unique dispersion process which allows mono modular and submicron particle size distributions • Submicron particle size distributions allow a good storage stability and film formation • Formulator can use solvent of choice • No additional solvent, so low VOC formulations can be prepared • Grades • Emulsion of a Liquid Epoxy Resin – commercial grade • Dispersion of an Epoxy Novolac Resin – commercial grade • Dispersion of a Solid Epoxy Resin – commercial grade Process Properties Ambient cured coatings

5. VOC free WB epoxy dispersions

6. Typical Particle Size distributions Particle size distribution of an aqueous dispersion of an epoxy novolac resin Particle size distribution of an aqueous dispersion of a solid epoxy resin

7. Storage Stability Submicron particle size distributions lead to excellent storage stabilities demonstrated with the example of a WB epoxy novolac dispersion XZ 92546.00 Only very light sediment after one year of storage at 23°C which can be easily stirred in

8. Viscosity profile of epoxy dispersion XZ 92533.00 Good shear thinning properties allowing good flow and spray properties Solid contents up to 54% without solvents can be achieved if high viscosities can be tolerated

9. Mechanical dispersion Process • Process patented by Dow: • Continuous feed of resin and water to the mixing unit under high shear • High viscous resins can be dispersed without the addition of solvents • Excellent transfer of process parameters from lab to pilot to manufacturing scale • Submicron and mono modular particle size distributions

10. Influence of process parameters Particle size can be influenced by the total flow rate

11. Influence of process parameters Significant increase in viscosity with decreasing particle size distribution

12. Solid Epoxy Resin Dispersion

13. Cure Rate Both Curing agents are based on water soluble epoxy amine adducts Drying times based on drying time recorder

14. Pot life As 2K WB epoxy systems don’t have necessarily a visible end of pot life like their solvent borne counterparts other properties are tested Some 2K WB epoxy systems based on Dow’s dispersion technology show excellent gloss retention over time

15. Anti-corrosive Primer White Component A Weight-% 1 Curing Agent 2 13,4 2 Demineralised water 29,1 3 TEGO Dispers 750W Tego-Chemie 1,6 4 BYK 019 / 024 (3:2) BYK Chemie 0,5 5 Omya BLR 3 Omya 17,5 6 Micro-Talc AT Extra Omya 9,0 7 Micro-Talc AT 1 Omya 8,0 8 Heucophos ZPA Heubach 10,0 9 Kronos 2059 Kronos 10,0 10 Aerosil R 972 Degussa 0.9 Total Component A: 100,0 Component B 1-Type Dispersion 87,0

16. Barrier properties • Good barrier properties against solvents, water and basic materials • The clear coated systems show some minor deficiencies against some acids • Fully formulated systems based on commercial available anticorrosion pigments achieve 1000 hours of salt spray resistance on pretreated steel panels • Corrosion/salt spray resistance on cold rolled steel of 1000 hours could be achieved with the help of adhesion promoters e.g. based on epoxy silane chemistry

17. Salt-Spray Test DIN 50021 • Exposure 1000 hours • Blistering: none (m0g0) • Under rusting: <1 mm • Adhesion: < GT1 • Scratch-Test: o.k. (K0) • Substrate • Cold Rolled Steel, Type R-46 (Q-panel)

18. Institutional Coating

19. Pot-life and Drying Dry Times (1.5 mil dry films) Set-To-Touch 0.4 hrs. Surface Dry 0.6 hrs. Dry Through 5.0 hrs. 20 Degree Gloss No Induction 101 30 Min. 101 1 Hr. 101 2 Hr. 92 3.5 Hrs. 78 4.5 Hrs. 65

20. Resistance Cure: 14 days @ R.T. conditions of 72 0F and 50-55 % R.H. Test Method: ASTM D-1308 ( covered spot test, 18 hr. exposure time, no recovery)

21. Combination Epoxy / PU Dispersion • Combinations are possible but appropriate hardener selection is required (clarity) • Gloss of cured mixtures is in the same high range as for the PUD alone • Flexibility is improved when PUD is added to Epoxy Dispersions • Coating hardness follows the ratio of Epoxy to PUD for 90% stoichiometric hardener ratio. • Especially solvent resistance is improved when epoxy dispersion is added to the PUD

22. Conclusions epoxy functional surfactant Continuous process + VOC free WB epoxy dispersions Excellent storage stability, film formation, mechanical properties, barrier properties Good fit for ambient cured coatings also in combination with DOW PUD`s