Introduction into powder coatings - · PDF fileDSM Coating Resins 1 Powder Coating - February...
Transcript of Introduction into powder coatings - · PDF fileDSM Coating Resins 1 Powder Coating - February...
DSM Coating ResinsPowder Coating - February 05 -
Introduction into powder coatings
DSM Coating Resins
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Powder Coating - February 05 -
Introduction into powder coatingsIntroduction into powder coatings
• Polymerisation• Chemistries
• chemical reaction• advantage/disadvantages
• Application• Melting/Curing process• Matting
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Powder Coating - February 05 -
Two types of Polymerisation processesTwo types of Polymerisation processes
� Addition polymerisation-A polymerization in which the growth of polymer chainsproceeds by addition reactions between molecules ofall degrees of polymerization (e.g. acrylics)
� Condensation polymerisation- A polymerization in which the growth of polymer chains
proceeds by condenstation reactions between molecules ofall degrees of polymerization with loss of small molecules like water. (e.g. polyesters)
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Raw materialsRaw materials
� Diols (glycols)�Neopentylglycol
�Ethyleneglycol
�propyleneglycol-1,2
� Polyalcohols�Trimethylolpropane
�glycerol
� Dicarboxylic acids�terephthalic acid
�isophthalic acid
� Polycarboxylic acids�trimellitic anhydride
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EsterificationEsterification
� Esterification:
� Acid + Alcohol Ester + Water
� Polyacid + Polyalcohol Polyester + Water
� Hydrolysis:
� Polyester + Water Polyacid + Polyalcohol
� Overall:
� Polyacid + Polyalcohol Polyester + Water
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Main reactionMain reaction
Excess of OH OH-functional polyester
Excess of COOH COOH-functional polyester
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Powder Coating FormulationPowder Coating Formulation
� Resin (polyester)
� Crosslinker
� Pigments / Fillers
� Flow agents
� Degassing agents
� Catalysts
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Chemistries (Binder systems)Chemistries (Binder systems)
• Interior(hybrid)
• Exterior
• bisphenol A epoxies
• Araldite PT 810 (TGIC)• Primid XL 552 / QM 1260• Araldite PT 910• Mix crosslinker• Uranox
• (blocked) Isocyanates• glycoluril
• Carboxylic polyester
• Carboxylic polyester
• Hydroxyl polyester
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Powder Coating - February 05 -
Overview of the characteristics of binder Overview of the characteristics of binder systemssystems
Polyester/ Epoxy
Polyester/ TGIC
Polyester/ Primid
Polyester/
PT 910
Uranox Uranox/Primid
Polyester/Isocyanateno split-off
Flexibility ++ ++ ++ ++ ++ ++ ++
Flow adjustability
++ ++ ++ ++ + ++ ++
Exterior durability
-- ++ ++ ++ + ++ ++
Powder stability
++ + + +/± ± + +
Colour stability- overbake- direct gas
oven
++
++++
+±
++++
±+
±+
++
Processing ++ ++ + + ++ ++ +/++
Split-off products
++ ++ - ++ ++ + ++
Blister-freelayer thickness
++ ++ - ++ ++ + +
Labelling ++ -- ++ ± ++ ++ ++
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HybridsHybrids
OHO
O
OH
O
OHHC
O
CH2
CH2
OO C
CH3
CH3
OCH2CH
CH2
O C
CH3
CH3
O
CH2
OH
HC
CH3
+
+CarboxylatedPolyester
Bisphenol A diglycidyl ethers
R1 O
O
OH
R2
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HybridsHybrids
- Disadvantage• Outdoor durability
+ Advantages• Price/performance• Flexibility• Large curing window• Ease of processing• Powder stability• Chemical resistance
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Carboxyl Polyesters for HybridsCarboxyl Polyesters for HybridsCrosslinkerCrosslinker: : bisphenolbisphenol A epoxiesA epoxies
• 50/50 systems
• 60/40 systems
• 70/30 systems
• Acid value 70-85
• Acid value 48-55
• Acid value 32-38
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Outdoor durable Outdoor durable CrosslinkersCrosslinkers
Araldite PT 810 Huntsman
XL 552 / QM 1260 EMS
PT 910/PT 912 Huntsman
Uranox DSM Resins
BF 1540 / BF 1320 Creanova
LS 2147 Bayer
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TGICTGIC
O
OO
O CH 2
CH
H2C C
H2C CH
CH 2
N
C
N
CH 2
HC CH 2
C
N
O
O
OHO
O
OH
O
OH
+
TGIC (triglycidylisocyanurate)
+CarboxylatedPolyester
R1 O
O
OH
R2
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TGICTGIC
- Disadvantage• Labeling
+ Advantages• Flexibility• Large curing window• Outdoor durability• Colour stability• Processing• Powder stability
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Primid (XL 552, QM 1260)Primid (XL 552, QM 1260)
OHO
O
OH
O
OH
OH
N
O
OH
N
OH
O
OH
Primid XL-552, ex-EMS Primid
+
CarboxylatedPolyester
+
R1 O
O
NR3
OH
OH2+
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Primid (XL 552, QM 1260)Primid (XL 552, QM 1260)
- Disadvantage• Yellowing tendency• Low blister-free layer thickness• Water sensitivity• Proces sensitivity
+ Advantages• Label free• System cost• Low curing temperatures• Outdoor durability• Powder stability
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PT 910 (PT 912)PT 910 (PT 912)
OHO
O
OH
O
OH
O
O OO
O O
O
OO
n
Araldite PT 910 and PT 912, ex-Vantico
0<n<1
+
CarboxylatedPolyester
+
R1 O
O
OH
R2
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PT 910 (PT 912)PT 910 (PT 912)
- Disadvantage• Xi Labeling• Lower cross-link density• Processing sensitivity
+ Advantages• Well-known chemistry• Excelent exterior durability• Thick layers• Colour stability
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Mixed cross linkerMixed cross linker
• Combination of carboxylated resin with 2 cross linkers
• e.g. PT 910/Primid• Primid/Uranox
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UranoxUranox
O
O
O
O
CH2
CH3
R
nOHO
O
OH
O
OH +
Uranox, ex-DSM Coating Resins
+CarboxylatedPolyester
R1 O
O
OH
R2
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UranoxUranox
- Disadvantage• Powder stability
(P7200 and P 7300)• Yellowing under extreme test
conditions
+ Advantages• No Hazard labelling• Processing properties• Pigment wetting
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PolyurethanesPolyurethanes
+
OH
OH OH
O H
NCO
H O
CN
O
O
R N N R R O
n
+ Internally blocked isocyanates
Hydroxylated polyester
R1 O NH
O
R2
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PolyurethanesPolyurethanes
- Disadvantage• Price• Caprolactam blocked types:• Split-off products
+ Advantages• Outdoor durability• Powder stability• Flow• Chemical resistance
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Polyester/cross linker ratio (Polyester/cross linker ratio (carboxylatedcarboxylatedresins)resins)
• Equivalent weight polyester• 56100 / AV = EW1
• Equivalent weight Cross-linker:EW2
• Stoichiometric resin ratio:• (EW1 / (EW1 + EW2))*100%
• Example: AV= 35• 56100 / 35 = 1600
• Primid XL 552: EW = 84
• (1600 / (1600 + 84))*100% =• 95% Polyester• 5% Primid XL 552
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Polyester/cross linker ratio (Polyester/cross linker ratio (HydroxylatedHydroxylatedresins)resins)
• - Equivalent weight polyester• 56100 / HV = EW1
• - Equivalent weight Cross-linker:EW2
• Stoichiometric resin ratio:• (EW1 / (EW1 + EW2))*100%
• Example: HV= 42• 56100 / 42 = 1336
• BF 1540: EW = 280
• (1336 / (1336 + 280))*100% =• 82% Polyester• 18% BF 1540
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Powder Coating - February 05 -
Polyester / Polyester / crosslinkercrosslinker ratio several Acid ratio several Acid valuesvalues
93/7
95/5
96/4
95/5
75/25
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91/9150Araldite PT 910
91/994/697/3100Primid QM 1260
93/795/597/384Primid XL 552
93/796/4110Araldite PT 810 (TGIC)
50/5060/4070/3080/20700Araldite GT 7004
80533520
AVEW
Ratio Polyester / crosslinker
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ApplicationApplication
CoronaAir + powder
High voltage supply
TriboAir + powder
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CoronaCorona PackagingPackaging
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CoronaCorona Faraday cageFaraday cage
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CoronaCorona Back ionisationBack ionisation
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TriboTribo
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Melting / curing Melting / curing procesproces melt cure stagesmelt cure stages
200°Chigh viscosityflow stopsx-linked film
25°Chigh viscosity
100°Cstart meltingdecrease viscosityincrease flowing
150°Cstart reactionincrease viscositydecrease flow
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Viscosity curvesViscosity curves
1
10
100
1000
10000
0 100 200 300 400 500 6000
50
100
150
200
250
high reactive low reactivenon reacting temperature profile
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Influence of melting rate on viscosityInfluence of melting rate on viscosity
0
5 0 0
1 0 0 0
1 5 0 0
2 0 0 0
2 5 0 0
3 0 0 0
3 5 0 0
4 0 0 0
4 5 0 0
0 1 2 3 4 5 6 7 8 9 10
Time (min)
visc
osity
80°C/min
20°C/min
40°C/min
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Simplified DSC curveSimplified DSC curve
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Influence of particle sizeInfluence of particle size
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Tg versus physical stabilityTg versus physical stability
0123456789
10
20 30 40 50 60 70
Powder Tg
Phys
ical
sta
bilit
y
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Powder Coating - February 05 -
Influence % crossInfluence % cross--linker on Tglinker on Tg(only TGIC and PT 910, Primid XL 552 and Epoxy resin Powder Tg (only TGIC and PT 910, Primid XL 552 and Epoxy resin Powder Tg not (hardly) influenced)not (hardly) influenced)
Influence % cross-linker on Tg
0
2
4
6
8
10
12
5 10 15 20 25 30 35 40
Acid Value
% c
ross
-link
er
5052545658606264666870
Pow
der T
g (C
) %TGIC
%PT 910
Resin Tg 64icw TGICResin Tg 68icw PT 910
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Powder Coating - February 05 -
Relation viscosity and resin TgRelation viscosity and resin Tg
0200
400600800
10001200
14001600
20 40 60 80
resin Tg
Visc
osity
dPa
s
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Powder Coating - February 05 -
MattingMatting
• Powders are more difficult to matt than wet paints
• Techniques• matting agents• dry blend
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Powder Coating - February 05 -
Mat powder coatings (Dry blend systems)Mat powder coatings (Dry blend systems)
• fast with slow,different AV or different chemistries• In generally wheatherability and mechanical properties
are OK• Sparkling effect• Extra processing step involved
• TGICE.g. P2220/P4800 with wax• Freedom of formulation
• TGIC/PUR• Freedom of formulation
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Mat powder coatingsMat powder coatings
• PrimidE.g. P870/P833, P873/P835 (optional with DT3329 )+ gloss setting, mechanical properties• water split off can give disturbances, gloss variations per layer thickness,
very low gloss is difficult
• PT910E.g. P2240/P3487 with wax (DT 3329)+ no splitt off• moderate mechanicals, powder stability, not very low gloss
• PT910/Primid+ low gloss possible• bad mechanicals