涂料生产与工艺(英文版).ppt

1、1,Processing & Production,2,Backgrounds on production,3,What 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.,4,What is Paint?,Paint is a dispersion o

2、f solid (pigment) particles in a solution of polymers.,5,Grade of dispersion,Effects: Optical properties Flow Durability Hiding power Gloss (Can) stability,6,Paint consists of:,Binder Solvent Thinner Additives Pigments Fillers etc.,Fluid / solid Fluid Fluid Fluid / solid Solid Solid .,7,Primary proc

3、esses,Wetting Separation of agglomerates Stabilization,8,Wetting,Removal of air, water and/or pollution from the surface of a particle.,9,Wetting,Surface tension liquid phase pigment phase Capillary forces Speed is mainly viscosity dependent (fluid phase),10,Breaking down agglomerates,Agglomerates A

4、ggregates Primary particles,11,Breaking down agglomerates,Shear stress () dependent Shear stress = shear rate x viscosity Shear rate, equipment dependent Viscosity, as high as possible for used equipment.,12,Stabilization,Prevent flocculation Entropical stabilization Steric hindrance Osmotic hindran

5、ce Electrical stabilization,13,Production process,Wetting,De-agglomeration,Stabilization,14,De-agglomeration,15,Actions,Add and homogenize,Disperse and/or grind,Add and homogenize,16,Stabilization,17,Amount of binder, sufficient to completely wet a known amount of pigment. Daniel: Wet point titratio

6、n Gardner-Coleman : Oil absorption (OA),Oil absorption,18,Daniels titration,Wet point Just completely wetted (dry paste) Flow point Binder solution is added, until flow is achieved on a vertical spatula,19,Flow point titration,Percentage binder (NV) in solution,25,75,50,Required volume solvent to re

7、ach Flow point (cm3),12,6,9,3,15,Titanium dioxide (20 gr) Alkyd binder White spirit,20,Production process,21,The letdown,Add while homogenizing Prevent temperature and viscosity differences Search the proper composition of dispersion and let down phase,22,Finishing of,Intolerance (solvent - binder)

8、pH-shock Temperature-shock Flocculation Extraction - migration Solvability Pigment-shock,23,Solvents,- Binder extraction - Solvent extraction,24,Composition: - Grinding phase - Letdown phase - Total Paint - Dry film,25,Composition: - Grinding phase - Letdown phase - Total Paint - Dry film,26,Composi

9、tion: - Grinding phase - Letdown phase - Total Paint - Dry film,27,Alternative production routes,28,Possible production problems,Solvent extraction,Binder extraction,29,Productionequipment,30,Which Equipment?,Dissolver,Dissolver and / or grindingmachines,Dissolver or mixer,31,Production equipment,Ma

10、in equipment Mixers Dissolvers Roller mills Bead Mills,Other Bins Pumps Filters Filling machines Test material,32,Mixers,Low speeds (0-8 m/s) Unlimited designs Mixing Homogenization Interval mixing De-aeration,33,Mixer types,Marine Propeller Axial flow3-15 m/s Homogenization, suspension, Heat transf

11、er,Rushton Turbine Radial flow3-7 m/s Dispersion, de-aeration,Disperser Radial flow8-30 m/s Dispersion,34,Mixer types,Pitched blade impeller Axial / radial flow3-10 m/s Homogenization, dispersion,Crossbeam impeller Axial flow1-10 m/s Homogenization, suspension,Contrary flow mixer Axial flow2-8 m/s H

12、omogenization, suspension, Heat transfer,35,Mixer types,Interference mixer Axial flow1-9 m/s Homogenization, suspension, Heat transfer, dispersion, de-airation,Interprop Axial flow2-10 m/s Homogenization, suspension, Heat transfer, dispersion, de-airation,Anchor impeller (scraper) Tangential flow 1-

13、5 m/s Suspension, heat transfer,36,Dissolver,Flat, toothed disk, rotating at high speed in a tank.,37,Dissolver,38,Types,Single disk,Double disk,Rotor -stator,39,Laminar / turbulent,Laminar,Turbulent,40,Reynolds,2000,41,Temperatureinfluenceonflow behaviour,42,Guggenheim (empirical),43,Guggenheim (Ex

14、ample),44,Influence rotation speed,10 m/s,20 m/s,30 m/s,45,Dissolvers,Advantage,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 solvent,46,Bead mills,47,Spalt system,Spac

15、e between housing and shaft Maximum 1/3 of bead diameter,48,Influence parameters,Less Higher Higher -Small,Improved Lower Lower HigherSmall,Less Lower Lower -Big,Improved Higher Higher HigherSmall,Improved - - HigherSmall,Improved Higher Higher HigherSmall,49,Single passage,50,Residence time,Average

16、 residence time of pigments is 3 minutes - Apparent linear speed is 0.4 cm/s - Tangential flow rate of beads is 2-8 m/s Thorough mixing in the mill results in spreaded residence time of pigments Spreaded residence time results in a wider particle size distribution.,51,Multiple passage,Circulating,Jo-jo grinding,52,Bead Mills,Advantage,Disadvantage,Reproducibility Minor supervision Relatively low energy requireme