NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 1 VOC-free Waterborne Epoxy Emulsions and Dispersions for Ambient Cure Coatings. - презентация

1 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 1 VOC-free Waterborne Epoxy Emulsions and Dispersions for Ambient Cure Coatings

2 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 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 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 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 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 4 Dows Technology Approach 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 Chemistry Process Properties + Ambient cured coatings

5 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 5 VOC free WB epoxy dispersions Aqueous dispersion based on Liquid Epoxy Resin Solid Epoxy Resin Epoxy Novolac Resin GradeXZ XZ XZ Epoxy Equivalent Weight (gr/eq) 194 – – – 204 Solid content % % % 23 °C Brookfield, mPas Typical average Particle size D[4.3] 0.5 µm

6 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 6 Typical Particle Size distributions Particle size distribution of an aqueous dispersion of a solid epoxy resin Particle size distribution of an aqueous dispersion of an epoxy novolac resin

7 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 7 Storage Stability Weeks of storage Average particle size D[4.3] Epoxy Equivalent Weight Brookfield viscosity at 23°C µm190 g/eq4660 mPas µm191 g/eq4200 mPas µm191 g/eq4200 mPas Submicron particle size distributions lead to excellent storage stabilities demonstrated with the example of a WB epoxy novolac dispersion XZ Only very light sediment after one year of storage at 23°C which can be easily stirred in

8 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 8 Viscosity profile of epoxy dispersion Solid contents up to 54% without solvents can be achieved if high viscosities can be tolerated XZ Good shear thinning properties allowing good flow and spray properties

9 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 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 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 10 Influence of process parameters Particle size can be influenced by the total flow rate

11 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 11 Significant increase in viscosity with decreasing particle size distribution Influence of process parameters

12 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 12 Solid Epoxy Resin Dispersion

13 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 13 Cure Rate Both Curing agents are based on water soluble epoxy amine adducts Drying times based on drying time recorder Curing agent 1 Curing agent 2 End of gel tear 2.9 h2.4 h End of scratch 7 h9.4 h

14 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 14 Pot life As 2K WB epoxy systems dont have necessarily a visible end of pot life like their solvent borne counterparts other properties are tested Some 2K WB epoxy systems based on Dows dispersion technology show excellent gloss retention over time

15 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 15 Anti-corrosive Primer White Component A Weight-% 1 Curing Agent 213,4 2 Demineralised water29,1 3 TEGO Dispers 750W Tego-Chemie 1,6 4 BYK 019 / 024 (3:2)BYK Chemie0,5 5 Omya BLR 3 Omya17,5 6 Micro-Talc AT ExtraOmya9,0 7 Micro-Talc AT 1Omya8,0 8 Heucophos ZPAHeubach10,0 9 Kronos 2059Kronos10,0 10 Aerosil R 972Degussa0.9 Total Component A:100,0 Component B 1-Type Dispersion87,0

16 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 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 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 17 Salt-Spray Test DIN 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 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 18 Institutional Coating

19 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 19 Pot-life and Drying Dry Times (1.5 mil dry films) Set-To-Touch0.4 hrs. Surface Dry0.6 hrs. Dry Through5.0 hrs. 20 Degree Gloss No Induction Min Hr Hr Hrs Hrs.65

20 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 20 Resistance Cure: 14 R.T. conditions of 72 0F and % R.H. Test Method: ASTM D-1308 ( covered spot test, 18 hr. exposure time, no recovery)

21 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 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 NEO Chemical Seminar 2007 Toine Dinnissen / March 28th 2007Page 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