Toine Dinnissen / March 27th 2007Page 1 NEO Chemical Seminar 2007 Cross-linking = Curing

Toine Dinnissen / March 27th 2007Page 2 NEO Chemical Seminar 2007 Reactive Sites O CH 3 O O O O O CH 2 OH CH CH 2 N Reaction via the OH-group[s] –Resole, Amine-formaldehyde resinsElevated Temperature –PolyisocyanatesRoom Temperature Reaction via the Epoxy-groups –Catalytic –Chemical Addition-reactionsElevated Temperature –Acids:Anhydrides, Phenols Base: Amines Room Temperature Polysulphides }

Toine Dinnissen / March 27th 2007Page 3 NEO Chemical Seminar 2007 Amine Reactions Linear Mw build-up.... O CH 3 O OH NH 2 N CH 2 H OH CH 2 NH 2 N H O CH 3 O O O NH 2 + +

Toine Dinnissen / March 27th 2007Page 4 NEO Chemical Seminar 2007 Amine Reactions followed by Cross-linking –Avoid vitrification O CH 3 O OH N CH 2 H OH CH 2 N HO CH 2 O O CH 3 O OH NH 2 N CH 2 H OH CH 2 NH 2 N H O CH 3 O O +

Toine Dinnissen / March 27th 2007Page 5 NEO Chemical Seminar 2007 Amine Reactions possible tertiary amine catalysed hydroxyl-cure –temperature helps O CH 3 O O + O O OH CH 2 N O CH 3 O O CH 2 N O CH 3 O OH

Toine Dinnissen / March 27th 2007Page 6 NEO Chemical Seminar 2007 Crosslink Density Assuming epoxy molecules are difunctional and hardener molecules are tetrafunctional. Note: Crosslinked network always tridimensional Solid epoxy resin Liquid epoxy resin Mole wt ~ 1000Mole weight ~ 380

Toine Dinnissen / March 27th 2007Page 7 NEO Chemical Seminar 2007 Bisphenol-A epoxy resins Influence of molecular weight of epoxy resin on key properties Pot life Drying time Solvent resistance Acid resistance Flexibility Viscosity EEW Mole weight370 D.E.R. 331 [Liquid] 500 D.E.R. 337 [Semi-solid] 700 D.E.R. 660 [Semi-solid] 1000 D.E.R. 671 [Solid] Trademark of The Dow Chemical Company

Toine Dinnissen / March 27th 2007Page 8 NEO Chemical Seminar 2007 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 hardener sometimes 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

Toine Dinnissen / March 27th 2007Page 9 NEO Chemical Seminar 2007 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: Molecular Weight is 146 Functionality is 6 phr = 24 * 100 / 200 = 12 grams H 2 N-CH 2 -CH 2 -N-CH 2 -CH 2 -N-CH 2 -CH 2 -NH 2 H H

Toine Dinnissen / March 27th 2007Page 10 NEO Chemical Seminar 2007 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. =

Toine Dinnissen / March 27th 2007Page 11 NEO Chemical Seminar 2007 = = 61 g 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 * Trademark of The Dow Chemical Company

Toine Dinnissen / March 27th 2007Page 12 NEO Chemical Seminar 2007 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

Toine Dinnissen / March 27th 2007Page 13 NEO Chemical Seminar 2007 Dow is NOT a Curing Agent supplier !!!