Cross-linking = Curing

1. Cross-linking = Curing

2. OH O O CH3 CH3 O O CH O O CH2 CH2 CH3 CH3 N Reactive Sites • Reaction via the OH-group[s] • Resole, Amine-formaldehyde resins Elevated Temperature • Polyisocyanates Room Temperature • Reaction via theEpoxy-groups • Catalytic • Chemical Addition-reactions Elevated Temperature • Acids: Anhydrides, Phenols Base:AminesRoom Temperature Polysulphides }

3. O O CH3 NH2 NH2 O O NH2 NH2 CH3 OH OH CH3 O O CH2 N CH2 N NH2 NH2 CH3 H H Amine Reactions • Linear Mw build-up.... + +

4. OH OH CH3 O CH3 + O O CH2 N CH2 N NH2 NH2 O O CH3 CH3 H H OH OH CH3 O O N CH2 N CH2 CH3 H CH2 O HO Amine Reactions • followed by Cross-linking • Avoid vitrification

5. O CH3 + OH O O CH3 CH3 O O N CH2 CH3 OH CH3 O O CH3 O CH3 O O N CH2 CH3 Amine Reactions • possible tertiary amine catalysed hydroxyl-cure • temperature helps

6. Crosslink Density Solid epoxy resinLiquid epoxy resin Mole wt ~ 1000 Mole weight ~ 380 Assuming epoxy molecules are difunctional and hardener molecules are tetrafunctional.Note: Crosslinked network always tridimensional

7. Bisphenol-A epoxy resinsInfluence of molecular weight of epoxy resin on key properties D.E.R.™ 331[Liquid] D.E.R. 337[Semi-solid] D.E.R. 660 [Semi-solid] D.E.R. 671[Solid] Mole weight 370 500 700 1000 EEW Viscosity Flexibility Acid resistance Solvent resistance Drying time Pot life ™ Trademark of The Dow Chemical Company

8. Amine Content • Amine Hydrogen Equivalent Weight [ AHEW ]unit: grams / equivalent.{ sometimes referred to as equivalent weight per active Hydrogen } • Definition: Grams of hardener containing one equivalent of N-H groups.or: Mw of the hardener divided by the number of active hydrogen per molecule • Parts per Hundred Resin [ phr ] unit: grams • Definition: grams of hardener needed per hundred grams of epoxy resin • Conversion: phr = { AHEW * 100 } / EEW • Amine Value { Aminzahl } unit: mg KOH / gram hardenersometimes called amine-index • Definition: mg KOH equivalent to one gram of hardener • Conversion: NO CORRELATION WITH AHEW • Amine content [ Aminwert ] unit: eq / kg • Definition: equivalents of N-H per kg hardener • Conversion: Amine content = 1000 / AHEW

9. H Molecular Weight is 146 H Functionality is 6 H2N-CH2-CH2-N-CH2-CH2-N-CH2-CH2-NH2 phr = 24 * 100 / 200 = 12 grams Calculation Example • Amine Hydrogen Equivalent Weight [ AHEW ] = 146 / 6 = 24 g / eq • Amine content = 1000 / 24 = 42 eq / kg In order to cure100 grams of resin with EEW = 200 g / eq one would need:

10. How to calculate Mixing-ratio • Amine Hydrogen Equivalent Weight [ AHEW ] • Epoxy Equivalent Weight [ EEW ] Amount of hardener needed per 100 g of epoxy resin 100 * AHEW EEW The mixing ratio can be optimised in order to achieve the desired performances. =

11. Example • Polypox H 043 : AHEW = 115 [ex. UPPC] • D.E.R.™ 331 epoxy resin : EEW = 188 Theoretical amount of hardener needed per 100 g of D.E.R. 331 epoxy resin 100 * 115 188 = = 61 g ™ Trademark of The Dow Chemical Company

12. Mixing and Pot-life • Mixing Quasi all ambient cure epoxy coatings are 2 pack systems. Excellent mixing of the epoxy with the hardener components and an accurate dosing are critical to achieve the expected performances • Pot life Amount of time available to apply the product after mixing. Pot life depends also on the temperature and amount of product. • Induction time With some systems, an induction time is required. Induction prevents blooming

13. Dow is “NOT” a Curing Agent supplier !!!