涂料生产与工艺(英文版)

1、Processing & Production1Backgrounds on production2What is Paint?A fluid, paste of powder product, mend to be applied in thin layers on a surface, where, by film formation, a solid layer is formed, which serves aesthetic, protective or special purposes.3What is Paint?Paint is a dispersion of solid (p

2、igment) particles in a solution of polymers.4Grade of dispersionEffects:Optical propertiesFlowDurabilityHiding powerGloss(Can) stability5Paint consists of:BinderSolventThinnerAdditivesPigmentsFillersetc.Fluid / solidFluidFluidFluid / solidSolidSolid.6Primary processesWettingSeparation of agglomerate

3、sStabilization7WettingRemoval of air, water and/or pollution from the surface of a particle. 8Wetting Surface tension liquid phase pigment phaseCapillary forcesSpeed is mainly viscosity dependent (fluid phase) 9Breaking down agglomeratesAgglomeratesAggregatesPrimary particles10Breaking down agglomer

4、atesShear stress () dependentShear stress = shear rate x viscosityShear rate, equipment dependentViscosity, as high as possible for used equipment.11StabilizationPrevent flocculationEntropical stabilizationSteric hindranceOsmotic hindranceElectrical stabilization12Production processWettingDe-agglome

5、rationStabilization13De-agglomeration14Actions Add andhomogenizeDisperse and/or grindAdd and homogenize15Stabilization16Amount of binder, sufficient to completely wet a known amount of pigment.Daniel: Wet point titrationGardner-Coleman : Oil absorption (OA)Oil absorption17Daniels titrationWet pointJ

6、ust completely wetted (dry paste)Flow pointBinder solution is added, until flow is achieved on a vertical spatula 18Flow point titrationPercentage binder (NV) in solution257550Required volume solvent to reach Flow point(cm3)BinderSolventSolution1269315Titanium dioxide (20 gr)Alkyd binderWhite spirit

7、Optimal concentrationFlocculation19“Dispersion” phaseFillers / PigmentsFillers / PigmentsBinderSolventLet DownBinderSolventPre-mixProduction processRequired paint20The letdownAdd while homogenizingPrevent temperature and viscosity differencesSearch the proper composition of dispersion and let down p

8、hase21Finishing ofIntolerance (solvent - binder)pH-shockTemperature-shockFlocculationExtraction - migrationSolvabilityPigment-shock22Solvents- Binder extraction- Solvent extraction23Composition:- Grinding phase- Letdown phase- Total Paint- Dry film24Composition:- Grinding phase- Letdown phase- Total

9、 Paint- Dry film25Composition:- Grinding phase- Letdown phase- Total Paint- Dry film26Alternative production routes27Possible production problemsSolvent extractionBinder extraction28Productionequipment29Which Equipment?DissolverDissolver and / orgrindingmachinesDissolver or mixer30Production equipme

10、ntMain equipmentMixersDissolversRoller millsBead MillsOtherBinsPumpsFiltersFilling machinesTest material31MixersLow speeds (0-8 m/s)Unlimited designsMixingHomogenization Interval mixingDe-aeration32Mixer typesMarine PropellerAxial flow3-15 m/sHomogenization, suspension, Heat transferRushton TurbineR

11、adial flow3-7 m/sDispersion, de-aerationDisperserRadial flow8-30 m/sDispersion33Mixer typesPitched blade impellerAxial / radial flow3-10 m/sHomogenization, dispersionCrossbeam impellerAxial flow1-10 m/sHomogenization, suspensionContrary flow mixerAxial flow2-8 m/sHomogenization, suspension,Heat tran

12、sfer34Mixer typesInterference mixerAxial flow1-9 m/sHomogenization, suspension, Heat transfer, dispersion, de-airationInterpropAxial flow2-10 m/sHomogenization, suspension,Heat transfer, dispersion, de-airationAnchor impeller (scraper)Tangential flow 1-5 m/sSuspension, heat transfer35DissolverFlat,

13、toothed disk, rotating at high speed in a tank.36Dissolver37TypesSingle diskDouble diskRotor -stator38Laminar / turbulentLaminarTurbulent39Reynolds200040Temperatureinfluenceonflow behaviour41Guggenheim (empirical)42Guggenheim (Example)43Influence rotation speed10 m/s20 m/s30 m/s44DissolversAdvantage

14、Disadvantage Low costs Needs small space Can be used as homogenizer Cleaning Temperature development Needs supervision Not suitable for “difficult” pigments Emission of dust and solvent45Bead millsSpalt SealingProduct outCooling water inCooling water outProduct inGrinding disk46Spalt systemSpace bet

15、ween housing and shaftMaximum 1/3 of bead diameter47Influence parametersLess Higher Higher -SmallImproved Lower Lower HigherSmallLess Lower Lower -Big Improved Higher Higher HigherSmallImproved - - HigherSmallImproved Higher Higher HigherSmallActionFineness Pressure Temp. PowerEffectFlowIncreaseSpee

16、d Increasepar. 0 IncreaseFill. % IncreaseDens. IncreaseVisco. Increase48Single passage49Residence timeAverage residence time of pigmentsis 3 minutes- Apparent linear speed is 0.4 cm/s- Tangential flow rate of beads is 2-8 m/sThorough mixing in the mill results in spreaded residence time of pigmentsSpreaded residence time results in a wider particle size distribution.50Multiple passageCirculatingJo-jo grinding51Bead MillsAdvantageDisadvantage Reproducibility Minor supervision Relatively low