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Werner J. BlankKing IndustriesNorwalk, CT 06852
You are now at www.wernerblank.com
HOME NEWS PUBLICATIONS LECTURES PATENTS DOWNLOADS
WHAT IS VOC (VOLATILE ORGANIC CONTENT)
USA“any organic compound that participates in atmospheric photochemical reactions except those designated by EPA as having negligible photochemical reactivity”
AUSTRALIAorganic compounds with a vapour pressure of more than 0.01 mm Hg at 21°C, and with a boiling point of less than 250°C.EUany organic compound having at 293.15K a vapour pressureof 0.01kPa or more, or having a corresponding volatilityunder the particular conditions of use
German Legislation Concerning the Environment
! 1970 basically 2 laws:Abfallbeseitigungsgesetz,Bundesimmisionschutzgesetz
! 1996 Alltogether approx. 2000 laws, edicts, regulations and recommendations by the authorities
WHY REDUCE VOC ?
ELIMINATION OF SOLVENT POLLUTIONREDUCTION IN OZONE FORMATIONSAFETY IN WORK PLACEHEALTH OF WORKERENERGY USE FOR CURE
How is VOC Regulated
Enduse Regional control Location, Amount of paint used Per Object (surface area)
0
1000
2000
3000
4000
5000
6000
7000
MM
LBS
1985 1997YEAR
SPECIAL
ARCHIT
OEM
RESIN CONSUMPTION1985 - 1997
3.5 %
4.6 %
SL2375
0
100
200
300
400
500
600
700
GAL
LON
S M
M
85 act 90 pred. 97 act 02 predYEAR
THINNERS
WATER BASED
SOLV BASED
SOLVENT CONSUMPTIONACTUAL & PREDICTED
SL2374
SOLVENT EMISSIONProduct life cycle
APPLICATIONTRANSFER
DRYINGFLASH OFF CURING
CLEANING
0 20 40 60
Air-atomize guns
Airless guns
Air-assisted airless guns
HVLP Guns
Electrostatic
Plural-Component Equipment
Liquefied CO2
Spray Equipment
SL1506
Survey Product Finishing Online Magazine March 1997
0 50 100 TRANSFER EFFICIENCY, %
Plural component Hand Spray
Airless sprayLiquid CO2 spray
HVLP gunsElectrostatic spray
Flow coatingDip coating
Curtain coatingRoller coatingElectrocoating
APPLICATION METHOD
SL2503
COATING TECHNOLOGIESHIGH SOLIDS - SOLVENT FREE
VISCOSITY/SOLIDS & POTLIFE/DRY TIMEWATERBORNE
COSOLVENT, APPLICATION CONDITIONSDRY-TIMEELECTROCOATING
PRODUCTION VOLUME, SUBSTRATECURE TEMPERATUREUV/EB COATING
COMPLEX OBJECTS, PIGMENTSPOWDER COATING
LOW FILM THICKNESS, CURE TEMPERATUREFLOW AND LEVELING
AdvantagesReduces VOC and HAP emissions Reduces inventory Reduces fire hazardsReduces number of spray applications to achievea given film thicknessHigher crosslink density improves abrasion and mar resistanceCompatible with conventional spray equipmentReduces safety and odor problemsReduced air makeup in ovens
HIGH SOLIDS - SOLVENT FREE COATINGS
HIGH SOLIDS - SOLVENT FREE COATINGS
DisadvantagesGenerally requires high cure temperatures Sensitive to inadequate cleaning of substrateIs difficult to control film thicknessTacky overspray; difficult to clean Might require paint heater in systemDifficult to control sagging Has narrow "time-temperature-cure" windowCannot use in dip or flow coatingIs difficult to repair Shorter pot-life than conventional coatings
Advantages
Reduces VOC and HAP emissions Can use conventional application processesReduces toxicity and odorIs easy to clean upReduces disposal of hazardous wasteCan recover and reuse some waterborne paintsNon-hazardous waste disposal might be possible
WATERBORNE COATINGS
WATERBORNE COATINGSDisadvantagesHas tendency to foam Clean surface requiredLonger drying times or increased oven temperaturesHas difficulty obtaining high gloss finishHas difficult cleanup once coating is curedHigher cost Conversion might be expensiveLower transfer efficiencies for electrostaticIncreases runs and sagsRequires good temperature/humidity controlHeated storage
ELECTROCOATING
Advantages
Utilizes over 90 percent of coating material Uniform coating on all surfaces High production ratesCorrosion-resistant coatingLow VOC and HAP emissions Can be fully automated
ELECTROCOATING
Disadvantages
Substrate limitation Separate lines for each colorHigh cost to installRequires sophisticated maintenanceDifficult coating bulky, small partsRequires de-ionized waterIs restricted to large volume finishingHas coating thickness limitationRequires corrosions-resistant equipment
RADIATION CURING UV/EB
Advantages
Lower VOC and HAP contentLower capital investment than conventional ovensShort cure timeLow energy costsConsistent performanceRequires small ovensLow air movement that reduces dust contaminationEasily installed/retrofittedReduces fire and explosion hazard
RADIATION CURING UV/EB
Disadvantages
Cure inhibition by pigmentsHigher RM costs for EB and UV coatingsPotential skin irritation problems with acrylate Shrinkage and adhesion problems with acrylateCuring sensitive to shape of part
POWDER COATINGAdvantagesNo solvent flash-off requiredNo coatings mix room neededMinimal oven length requiredLow ventilation requiredLess floor space requiredVOC and HAP compliant, i.e., no solventsGood corrosion resistanceHigh transfer efficiencies, 95-99%Saves energy Requires little operator expertise No hazardous overspray, waste sludgeReduces worker exposure to solvent vapors
POWDER COATINGDisadvantages
High cure temperature Small batches expensive to manufacture Metallic powder coatings not as attractive Appearance problems Enhances Faraday cage effect Difficult to achieve thin films below 1.0-1.5 milsMay cause powder clumping Difficult to change colors Needs cool, dry storage area Must pretreat substrate
COATING TECHNOLOGIES
HIGH SOLIDS - SOLVENT FREEVISCOSITY/SOLIDS, REACTION PRODUCTS
WATERBORNE COSOLVENT, REACTION PRODUCTS
ELECTROCOATINGCOSOLVENTS, REACTION PRODUCTS
UV/EB COATINGPOWDER COATING
High Solids Challenges
Nonvolatile - ViscosityCrosslinkingNetwork formationApplication characteristics
Potlife - reactivityRheology
SaggingPigmentation - Flocculation
Glass Transition Temperature
Structure
Molecular weight
Functional groups
Crosslinking
Viscosity
Physical properties
Chemical properties
Tg
Mobility of polymer chainsFree volume
1E-1
1E0
1E1
1E2
1E3
VISC
OSI
TY, P
OIS
E
0 50 100 150 200 TEMPERATURE, °C
VISCOSITY - TEMPERATUREOLIGOMERS MW 500
SL2502
Tg -50 to 60°C in 10°C
- 50°
60°
log η T = 13 - 17.44(T-Tg)
51.6+(T-Tg)
1E0
1E1
1E2
1E3
VISC
OSI
TY, P
OIS
E
0 50 100 150 200 TEMPERATURE, °C
500 1000 2000 4000 10000
VISCOSITY - TEMPERATUREOLIGOMERS, Tg 50°C
SL2500
T g o = T g in f -k
Mn
WATERBORNE COATINGS - COSOLVENTS
EMULSIONS-DISPERSIONS WATER-SOLUBLE
COALESCENCEOPEN TIMEFLOW - LEVELINGGLOSSADDITIVES
MANUFACTUREHANDLINGDILUTIONOPEN TIMEBLISTERING FLOW - LEVELING
Characteristic
Functional groupsAmount of functional groups*, MEQ/gSurfactantParticle size, micronMolecular weightFilm uniformityFilm formationCosolvent
WATERBORNE POLYMERS
Emulsion/dispersion polymerNon-random
0 to 2Yes0.1-2.0104-106
HeterogeneousTg dependentCoalescence
Characteristic
Functional groupsAmount of functional groups, MEQ/gSurfactantParticle size, micronMolecular weightFilm uniformityFilm formationCosolvent
WATERBORNE POLYMERS
Solution or bulk
Random distribution
0.5 to 2No0.01 to 0.1103-104
HomogenousNo Tg effectDispersion-synthesis
Chemistry
Non-ionic Polyether polyol Bisphenol A EO-PO diols Urethane diolsPolyester polyol Melamine resins Epoxy aliphaticUnsaturated compound
Resin COOH functional
Advantage - disadvantage
Water sensitivityExterior durabilityExterior durabilityCostHydrolytic stability Heat cure, formaldehydeNot stableLight stability, color
Amine
WATERBORNE REACTIVE DILUENT-COSOLVENTS
CROSSLINKING REACTIONWHY CROSSLINKING
RESISTANCE PROPERTIESCHEMICALSOLVENTCORROSION
MECHANICAL PROPERTIESHARDNESSFLEXIBILITY
INCREASE IN MOLECULAR WEIGHT-NETWORK
CROSSLINKING REACTION
Condensation reaction
R-H + X-L R-X + LH
ADVANTAGE
STABILITY-CURE RESPONSE
DISADVANTAGE
WEIGHT LOSSVOCFILM SHRINKAGESTRESSGLOSSCOST
CONDENSATION REACTIONS
Hydroxyl-carboxyl
Amino resins, melamine, urea formaldehydeFORMALDEHYDE, ALCOHOL, WATER
Blocked isocyanateKETOXIME, PYRAZOL, ALCOHOL
Silane, siloxaneALCOHOL
Hydroxyethyl amide -carboxylWATER
Methylol amide, glycoluril, cyclic ureaWATER
WATER
0
100
200
300
400
500
600
VOC
g/l
CALC. REACT. CALC. REACT.
VOC OF ACRYLIC/HMMM & DILUENTREACTION WEIGHT LOSS
ACRYLIC/HMMM80/20 ACRYLIC/DILUENT/HMMM
43/27/30
SL2389
0
50
100
150
VOC
g/l
CALC. REACTION
VOC OF POLYOL/HMMMREACTION WEIGHT LOSS
POLYOL/HMMM60/40
SL2390
POLYOL/HMMM60/40
Ring Opening and Addition Reaction
Epoxy, Glycidyl, Cycloaliphatic, OxetaneUretdioneCarbonateAzetidine2-OxazolineCarbodiimideAziridineAzlactoneCyclic urea acylIsocyanateMichael Addition
Approach
Molecular weightMolecular weightFunctional groupsFunctional groups typeCrosslinking typeCrosslinkingDispersion of resinWater addition
Details
<500Narrow MW distribution2-3 per polymer chainEnd groups, H-bond.Ring openingHydrogen bondingHigh Tg hetero. phase Breaking of H-bonds
REDUCTION OF VOC IN HIGH SOLIDS
1E0
1E1
1E2
1E3
1E4
TIM
E. m
inut
e
0.0001 0.001 0.01 0.1 DBTDL, Sn %
Potlife TACK FREE
PE/HDI-TRIMERCATALYST REACTION RATE
SL2245
COATING TECHNOLOGIES
HIGH SOLIDS - SOLVENT FREE
WATERBORNE
ELECTROCOATING
UV/EB COATINGPOWDER COATING
LOW MW, X-LINKING, H-BONDING
REACTIVE DILUENT, X-LINKING
REACTIVE DILUENT, X-LINKING
Pioneer in Waterborne CoatingsDr. Herbert Hönel
Vionova
Acknowledgement
King Industries Inc.Leonard J. CalboCarl G. Seefried
wblank@kingindustries.comwww.wernerblank.comwww.kingindustries.com