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Toine Dinnissen / March 27th 2007 Page 1 NEO Chemical Seminar 2007 Cross-linking = Curing
Toine Dinnissen / March 27th 2007 Page 1
NEO Chemical Seminar 2007
Cross-linking = Curing
Toine Dinnissen / March 27th 2007 Page 2
NEO Chemical Seminar 2007
Reactive Sites
O
CH3
CH3
O OO
CH3
CH3O
O
CH2
OH
CH
CH2
N
Reaction via the OH-group[s]– Resole, Amine-formaldehyde resins Elevated Temperature
– Polyisocyanates Room Temperature
Reaction via the Epoxy-groups– Catalytic
– Chemical Addition-reactions Elevated Temperature
– Acids: Anhydrides, PhenolsBase: Amines Room Temperature
Polysulphides
}
Toine Dinnissen / March 27th 2007 Page 3
NEO Chemical Seminar 2007
Amine Reactions
• Linear Mw build-up....
O
CH3
CH3
O
OH
NH2N CH2
H
OH
CH2 NH2N
H
O
CH3
CH3
O
OO
NH2NH2
NH2NH2++
Toine Dinnissen / March 27th 2007 Page 4
NEO Chemical Seminar 2007
Amine Reactions
• followed by Cross-linking– Avoid vitrification
O
CH3
CH3
O
OH
N CH2
H
OH
CH2 N
HO
CH2
O
O
CH3
CH3
O
OH
NH2N CH2
H
OH
CH2 NH2N
H
O
CH3
CH3
O
O
+
Toine Dinnissen / March 27th 2007 Page 5
NEO Chemical Seminar 2007
Amine Reactions
• possible tertiary amine catalysed hydroxyl-cure
– temperature helpsO
CH3
CH3
O
O
+O
CH3
CH3
O
OH
CH2 N
O
CH3
CH3
O
O
CH2 N
O
CH3
CH3
O
OH
Toine Dinnissen / March 27th 2007 Page 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 ~ 1000 Mole weight ~ 380
Toine Dinnissen / March 27th 2007 Page 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 weight 370
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 2007 Page 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 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
Toine Dinnissen / March 27th 2007 Page 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 146Functionality is 6
phr = 24 * 100 / 200 = 12 grams
H2N-CH2-CH2-N-CH2-CH2-N-CH2-CH2-NH2
HH
Toine Dinnissen / March 27th 2007 Page 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
EEWThe mixing ratio can be optimised in order to achieve the desired performances.
=
Toine Dinnissen / March 27th 2007 Page 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 * 115
188
™ Trademark of The Dow Chemical Company
Toine Dinnissen / March 27th 2007 Page 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 timeWith some systems, an induction time is required.
Induction prevents blooming
Toine Dinnissen / March 27th 2007 Page 13
NEO Chemical Seminar 2007
Dow is “NOT” a Curing Agent supplier !!!
