1、Waterborne Plastic Coatings,Dager Huang 2010-9-10,Content,General waterborne product introduction,Principle CDF Facilities: Toronto, Canada: Styling, Customer Support, Development Stockholm, Sweden: Styling, Customer Support, R&D Guangzhou, China: Styling, Customer Support, R&D Tianjin, China: Styli
2、ng, Customer Support Seoul, Korea: Styling, Customer Support, Development,General waterborne product introduction,Becker waterborne system (Chinese market),General waterborne product introduction,PC/ABS dash board,PC,ABS hand grip,PC, ABS PC/ABS door trim,ABS,PVC steering wheel,PS,PC,ABS gear stick,
3、Interiorautomotive,General waterborne product introduction,PC, Topcoat single 1 coat black,PC, 2 coat system of basecoat and clear coat,Mobile phone,Optional basecoat depending on Aesthetics requirements. Some special manufacturing process work on this layer, i.e. ink painting, bronzing,General wate
4、rborne product introduction,Person computer,Optional basecoat depending on Aesthetics requirements. Some special manufacturing process work on this layer, i.e. ink painting, bronzing,PC Aesthetic high gloss coatings,PS, ABS, PC low gloss coatings,PC.ABS 1-layer PU coatings,PC 1-layer UV/PU coatings,
5、Waterborne system property,Waterborne technology Description of General Chemistry: Various curing mechanism for basecoat Waterborne UV and soft touch topcoat available Recommended Application Market Areas Where water borne system is desired Advantages & Shortcomings Low/No VOC Further development in
6、 waterborne topcoat technology needed Comment on Application/process Some upgrading of application equipment to resist water,Waterborne system property,What is waterborne paint?Water is only a part of the volatile components.Binder (Resin) is what WB paint are based on, the one that holds the film t
7、ogetherEmulsion the dispersed binder particles is dispersed in the water with a help of surfactant enable emulsion by lowering the surface tension of the liquids- eg. oil and water will only blend if surfactant is addedCoalescence a process which the film is build, small amount of solvent is needed
8、for the film-building, the solvent draws the binder particles together and soften it to build a film once the water have evaporatedIrreversible network structures when the film is build it will not be dissolved again by water or solvent that originally carried it.,Waterborne system property,Why wate
9、rborne?Environmental friendly - reduces amount of Volatile Organic Content (VOC) significantly (50%) Less hazardous to your employeesLess toxic and non-explosiveNo solvent attacks on sensitive substratesMetallic effects and Silvers are not an obstacle anymoreEasier and cheaper to clean the equipment
10、s lesser need of solvents for cleaning the equipmentsA great goodwill value towards the consumers,Waterborne system property,Transportation and storage Can be stored on a shelf and remain suspended without needing any periodic mixing WB coatings generally are housed in plastic or in a stainless stee
11、l containers to avoid corrosion WB coatings are sensitive to freezing and must be kept in a temperature controlled storage and transport,Waterborne system property,Spray Booth Proper control of temperature and humidity:Water evaporation efficiency is very dependent on the temperature and humidity Hi
12、gher humidity and lower temperature means slower evaporation Air movement in the booth increases the evaporation efficiency of the paint In high humidity areas, sufficient air movement is even more critical.,Waterborne system property,Spray Gun WB-paint may require higher atomization pressure, fan p
13、ressure and different needle nozzle set up A designated spray gun for the WB-paints is preferable, makes the cleaning easier and lessen the risk for contamination The spray gun has to be free from solvents or oils before using it for the WB-paint rinse the gun first with solvent and then water befor
14、e using it to spray WB-paint Clean the spray gun with hot water after use,Waterborne system property,Viscosity The viscosity has to be adjusted before use for the best application and appearance the viscosity will depend on the application condition and the capacity of the painting line Only De-Ioni
15、zed water is recommended when adjusting the viscosity! Do not use solvent when reducing the viscosity solvent causes flocullation Very high viscosity may cause bad wetting and bad leveling which may lead to bad film building and bad pigment orientation Very low viscosity may cause sagging and diffic
16、ulties in building the DFT (Dry Film Thickness). Needs several spray passes in order to achieved the right DFT and appearance,Waterborne system property,Film Building Waterborne paints needs a small amount of solvent in order to build a film on the surface of the painted parts Film building is essen
17、tial for the paint it will affect the technical performance of the paint Broken or incomplete film build will cause faster deterioration of the paint Too dry spraying or bad wetting causes poor film building,Waterborne system property,Wetting and Leveling Contamination on the substrate or spray guns
18、 may cause bad wetting and leveling eg. crater building on the surface Very high viscosity may also lead to bad wetting and leveling eg. mottled and/or orange peeled surface Poor spraying technique may also lead to bad wetting and leveling eg. very dry or very wet spraying - specially for waterborne
19、s,Waterborne system property,Spraying Technique Waterborne paint requires a different spraying technique compared to solventborne WB-paint needs a drier spraying conditions compared to SB-paint in order to achieved a better surface as well as drying efficiency because water evaporates much slower th
20、an solvents Spraying too wet causes sagging and bad appearance especially for metallic effects and silver also causes darkening on the edges especially for transparent coatings Spraying too dry may cause bad film building which may lead to bad performance of the paint and added number of spraying pa
21、sses,Waterborne system property,Spraying Advice Use higher atomizing pressure if needed helps to achieved a better pigment orientation and a smoother surface If possible the distance of the spray gun from the parts to be sprayed on can also be adjusted to improve spraying process Adjust the fan pres
22、sure if needed wider spray feed also helps to spray evenly and smoothly For metallic effects and silvers a lower spraying viscosity is recommended to achieved the best appearance. This may require increased spray passes. WB-paints requires much lower paintflow compared to SB-paints,Waterborne system
23、 property,Flash Off and Drying WB paint has to be allowed to flash until it appears to be uniformly dry on the surface before force drying. The length of the flash off time varies depending on the humidity and the temperature in the room It is very important that the basecoat film is allowed to dry
24、thoroughly before spraying the topcoat. If some amount of water still remains in the basecoat after the topcoat had been applied it will affect significantly the technical performance of the paint system, eg. failure in ageing test, temperature cycle testCuring condition is improtnat, film build nee
25、d to a specifically baking temperature. Lower than this tempertaure, the film will become faster deterioration and show the weaken performance.,Waterborne system property,Waterborne application process,Ink painting or bronzing,For some special substrate: PA+50%GF, solvent primer is recommended,Topco
26、at combination,Waterborne application trouble shooting,Poor adhesion (附着力) Coating is easily removed from substrate or from primer coat, but hardness and mar resistance are maintained. Causes: Improper surface preparation Painting over oil, grease, or other contaminants Improper curing schedule Poor
27、 substrate integrity Incompatibility of one coat to another or to substrate,Waterborne application trouble shooting,Poor adhesion,Remedy: Remove coating, pretreat properly and refinish If poor substrate integrity, problem may not be solved.,Prevention: Ensure proper pretreatment Surface to be painte
28、d must be thoroughly clean and dry. Use recommended curing schedule. Ensure that substrate has good integrity. Follow acceptable practices using compatible materials.,Waterborne application trouble shooting,Blushing (发雾) Associated with lacquers. Appearance: the finish turns milky looking. Cause: Fa
29、st evaporating thinners in high humidity Improper thinners Condensation on substrate,Waterborne application trouble shooting,Blushing,Remedy: Add slower- evaporating thinners and re-spray. Sand and refinish,Prevention: Keep paint and surface to be painted at room temperature Use only recommended thi
30、nners Use slower-evaporating thinners when spraying in high humidity and warm temperatures.,Waterborne application trouble shooting,Brittleness (发脆) Appearance: coating displays excessive rigidity and flakes off when scraped.Causes: Overbaking. Excessive temperature and/or excessive time in oven Exc
31、essive film build Incompatibility of one coat to another or to substrate Improper surface preparation.,Waterborne application trouble shooting,Remedy: Remove coating and refinish.,Prevention: Avoid overbaking Reduce film build Follow recommended practices using compatible materials. Ensure proper pr
32、etreatment.,Brittleness,Waterborne application trouble shooting,Cratering (缩孔) (Fisheyes, Pitting)Appearance: Small crater-like depressions in the film Causes: Improper cleaning of substrate Oil, water or other contaminant in spray lines Silicone or other contaminant in working area atmosphere Low f
33、ilm build,Waterborne application trouble shooting,Cratering,Remedy: Sand and refinish Prevention: Surface to be painted must be thoroughly clean and dry Increase film build,Prevention: Use proper maintenance to prevent contaminants from entering spray lines. Eliminate contaminants from entering appl
34、ication areas.,Waterborne application trouble shooting,Dirt in Finish (污点) Appearance: Foreign particles dried in paint film Cause: Improper cleaning of the substrate Defective air regulator cleaning filter Dirty working area Defective or dirty air inlet filters in spray booth and/or ovens Dirty spr
35、ay equipment Dirt in oven or paint Insufficient agitation or paint-settling,Waterborne application trouble shooting,Dirt in Finish,Remedy: Sand and refinish Prevention: Clean surface thoroughly Be sure all equipment is clean Replace air inlet filters if dirty or defective Maintain a clean spray area
36、.,Clean or replace filters in solvent lines, air regulator, compressor , and paint lines. Keep all paint containers closed to prevent contamination. Periodically clean ovens Flush paint lines thoroughly with clean solvent when not in use and prior to changing paints Agitate paint thoroughly before u
37、sing,Waterborne application trouble shooting,Mottling (水纹/斑纹) Appearance: Streaky or blotchy appearance, generally associated with metallic finishes. Cause: Excessive wetting of some areas Heavier film thicknesses in some areas Improper spray technique,Waterborne application trouble shooting,Mottlin
38、g,Remedy: Sand and refinish,Prevention: Avoid excessive wetting or heavy build-up in local areas Be careful not to over-reduce paint Employ proper spray technique,Waterborne application trouble shooting,Orange Peel (Dry Spray) (桔皮) Appearance: Resembles the skin of an orange Causes: Under reduction
39、Improper thinning solvent-too fast evaporating Low film build Improper air pressure Lack of proper flow Paint temperature too low Substrate temperature too high,Waterborne application trouble shooting,Orange Peel,Remedy: Sand and refinishPrevention: Lower viscosity of paint Reduce with slower evapor
40、ating solvents,Proper air and application equipment adjustments Maintain constant paint and substrate temperature,Waterborne application trouble shooting,Runs (Sags) (流挂) Appearance: Running of the paint film in rivulets; mass slippage of the total film Cause: Over reduction Improper thinners-too sl
41、ow evaporating Excessive film build Paint temperature too high Substrate temperature too low Insufficient agitation of paint-separation,Waterborne application trouble shooting,Runs (Sags),Remedy: Sand and refinish,Prevention: Use recommended thinner at specified reduction and air pressure Decrease f
42、ilm build Maintain constant paint and substrate temperature Agitate paint thoroughly before using,Waterborne application trouble shooting,Undercoat Show Through (露底),Appearance: Variations in the surface color; surface undercoat is visible through topcoat. Cause: Low film build Insufficient agitatio
43、n of paint-settling Remedy: Refinish Prevention: Increase film build Agitate paint thoroughly before using,Waterborne application trouble shooting,Wrinkling (起皱) Appearance: Puckering of enamel Prune skin effect Loss of gloss as film dries (minute wrinkling not visible to the naked eye). Causes: Exc
44、essive film build Surface drying trapping solvents Fresh film subjected to heat too soon Contamination in oven or paint.,Waterborne application trouble shooting,Wrinkling,Remedy: Remove wrinkled coating and refinish Prevention: Decrease film build Clean all agitation equipment and paint lines thorou
45、ghly before changing colors or products.,Periodically clean oven. NOTE: Do not use chlorinated solvents or acid for cleaning ovens or areas around ovens.,Waterborne application trouble shooting,Blistering (起泡/痱子) (Solvent Popping, Pinholes)Appearance: Small swelled areas like a water blister on huma
46、n skin Pin point holes in finish Lack of gloss if blisters are minute Broken edged craters if the blisters have burst,Waterborne application trouble shooting,BlisteringCauses: Improper thinning solvent-too fast evaporating Excessive film build-trapped solvents Excessive temperature in first oven zon
47、e Insufficient flash off time before baking Gasses entrapped in the substrate during the manufacturing process are forced out through the coating when baked at high temperatures.,Waterborne application trouble shooting,Blistering,Remedy: Sand and refinish,Prevention: Reduce with slower evaporating solvents Reduce film build Reduce temperature in first oven zone Increase flash off time prior to baking Reduce overall oven temperature,Waterborne application trouble shooting,Thank you for your attention!,
