A New Approach to Anticipating Florida Outdoor Irradiance Exposure Results Using Lab Weathering A new accelerated weathering test method using xenon arc test chambers
Why Do Coating Users Care about Weathering Test Development? Warranty costs are the responsibility of the manufacturer not the paint supplier Strong desire to reduce development time of products
Why Do Coating Users Care about Weathering Test Development? Strong desire to rapidly introduce new coating systems or new colors in response to environmental pressure or consumer preferences
Why Do Coating Users Care about Weathering Test Development? Unique Position: OEM s must evaluate and qualify coatings and other materials from many suppliers
Perfect Weathering Test Rapid 10X acceleration over natural weathering Accurate minimal false positives and false negatives Machine agnostic able to run test protocol in a variety of accelerated weathering devices. Minimal sample investigation post exposure Engineers want a box Put samples in the box Expose Take samples out and evaluate
Introduction Automotive Manufacturers & Coatings Companies Always Introducing New Systems OEMs Require up to 5 Years Natural Outdoor Weathering Accelerated Weathering Used to Shorten Development & Approval Time
Goals - Outdoor Gain Better Understanding of Natural Weathering Light Spectrum Temperature Moisture Obtain Suitable Body of Field Data to Develop Accelerated Test
Goals Lab Weathering Replicate Degradation Seen in Field Chemical Physical Develop New Accelerated Weathering Test Link Field Failures to New Test
Outdoor Data Data Collected Temperature Air, Black Panel, Relative Humidity and Dew Point Wind Rain Speed and Direction Amount, Duration, Rate Accumulation Solar Radiation Panel Weight Wetness, Dew Events and Rain Events
Outdoor Data Weather Station Installed at Bayer Site Jacksonville, FL 2004 to 2007 Moved to Homestead, FL (Q-Lab) 2008 to?
Water - Outdoor Mass of Panel Measured Every 5 min Panel + Water Calibrated per Schedule Care Taken to Ensure no Animal or Bird Influence Able to see Rain vs Dew + Water-uptake
Data Allowed Development of Accurate Model Time & Amounts of Wetness Difference Between Rain & Dew Model Not Mathematically Complex Follows Syntactical Description Straightforward Expression of Algorithm
Rain & Dew Grams Cumulative Grams Actual Water Data vs. Derived Model 2005 Rain & Dew / Scale vs Model 140 90000 120 100 Water Model Scale Water 80000 70000 60000 80 50000 Scale Rain Water 60 40000 40 20 Scale Dew 30000 20000 10000 0 7/15 7/25 8/4 8/14 8/24 0
Grams Water on Panel Dew Data Example 30 25 2006 Dew Formation C 20 15 10 B E 5 D 0 Wind Noise 6/30 7/1 7/2 7/3 7/4 7/5 A
What was learned from outdoor data collected Laying the ground work for a new accelerated test
Outdoor Data Learned several key Items Needed to better match sunlight SPD in xenon testers Higher irradiance may work Test temperatures need to be reasonable Panels were wet longer that commonly believed
Light Spectrum New optical filter now commercially available by all major equipment Manufacturers Daylight F (Q-Lab) Rightlight (Atlas) Better match to solar spectrum Produces better results Allows slightly higher irradiance
Intensity (W/m 2 ) SPD of SAE J2527 Optical Filters 2.000 1.800 1.600 1.400 1.200 1.000 Boro/Boro Quartz/Boro 0.800 0.600 Miami Sunlight 0.400 0.200 0.000 250 350 450 550 650 750 Wavelength (nm)
Intensity (W/m 2 ) SPD of SAE J2527 Optical Filters 0.600 0.500 0.400 0.300 Quartz/Boro 0.200 Boro/Boro 0.100 Miami Sunlight 0.000 250 260 270 280 290 300 310 320 330 340 350 Wavelength (nm)
Infrared Spectroscopy Spectrum Changes with Exposure specific generic Exposed Unexposed 3600 3100 2600 2100 1600 1100 600 Wavenumbers (cm -1 )
Match Chemical Changes in Coatings: Accelerated vs. Natural Weathered Use peak heights a b c d Unexposed Plot Ratios D[a/b] versus D[c/d] to compare spectra 1850 1650 1450 1250 Wavenumber (cm -1 ) 1050 850 650 Peters/Misovski
Why Might High Irradiance Work Explored different light sources Explored different optical filters Accelerated Outdoor weathering (Q-Trac) provided tantalizing results Better match to sunlight just might work
D(a/b) 8 7 6 Atlas CIRA/SL Xenon Polyester/Urethane Q-Lab Daylight-Q Q-Trac - NTW Atlas B/B Xenon Q-Lab Daylight B/B 5 4 3 FL QUV UVA340 SUPRAX Q-Lab Q/B Xenon 2 1 0 AZ 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 D(c/d) SEPAP Atlas Q/B Xenon Peters/Misovski/Roberts/Lemaire/Fischer
D(a/b) 8 7 6 Polyester/Urethane Q-Trac = >4 Suns 5 4 FL 3 2 Match suggests high light intensity can be used to accelerate weathering. 1 0 AZ 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 D(c/d) Peters/Misovski
Borosilicate filtered xenon arc Results from J2527 Boro/Boro do not match FL exposure Q-Trac Florida Peters/Misovski
Irradiance (W/m2) SPD new Optical Filter 3.5 3.0 2.5 2.0 1.5 Daylight F 1.0 0.5 Sunlight 0.0 250 300 350 400 450 500 550 600 650 700 750 800 Wavelength (nm)
Intensity (W/m 2 ) SPD on Log Scale New Filter All data normalized to 0.6 W/m2 @340 nm 1 FIlter Comparison 0.1 Boro/Boro Miami Sunlight Daylight F 0.01 0.001 250 270 290 310 330 350 370 390 Wavelength (nm)
D (a/b) 5 4.5 4 Chemical Match with new Filter #1a 3.5 3 2.5 New Filter #1b 2 1.5 1 Florida 0.5 0 D (c/d) 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Temperature Mostly a function to accelerate water uptake Important not to exceed service maximum Realistic temperatures increase correlation Stepped temperatures
Water - Lab Weathering Establish Max Amount Painted Panel Hold Establish minimum amount of water that must reach the specimens Determine if Accelerated Weathering Devices Can Produce Enough Water
Addressing Reproducibility Need to Better Understand Amount of Water Actually Reaching Samples Need a Repeatable & Reproducible way to Measure Water Establish Minimum Amount of Water That Must Reach Test Panel
Sponge Test Can be Used in Both Flat Array & Rotating Drum Same Size & Type of Sponge in Same Holder Type used in Both Machines Results were Repeatable & Reproducible
Data for Outdoor Correlation Establish a body of real world data to be used in developing the accelerated lab test Included production systems & specially engineered systems
Outdoor Samples All Samples Prepared by One Lab 106 Combinations Prepared 4 Colors Black, White, Blue, Red Waterborne & Solventborne Base Solventborne Clear Different Layering Systems With and Without UVA and HALS Sample set includes most common field failures (cracking, gloss loss, color fade, erosion, delamination) and known good control systems
Outdoor Weathering Per SAE J1976 5º South Facing Open Back Exposure Time Full Set Summer 2006 Partial Set Summer 2007 Expose Until Failure Evaluations Every 6 Months Performed by Same Lab
Test Development Many years of experimentation 1 st group: BASF, Bayer, Ford, Q-Lab 2 nd group: Honda, Boeing, Atlas Dozens of different approaches Multiple runs of final test to ensure repeatability & reproducibility
Exposure Targets for New Accelerated Weathering Test South Florida target to match (global benchmark location) Increase time of wetness - Mimic real world behavior where panels are wet 12+ hrs/day in Florida Increase acceleration Higher intensity light (correct SPD) Never spray panels during light step never rains when sun is shining brightly Scale dose to diurnal cycles Short light cycles and short wet cycles. Conflicts with need for longer wet times. Keep temperatures realistic.
Radiation Intensity or Water Content (arbitrary units) Florida Panel Exposure 1.2 1 Night Day Night Day Radiation Intensity 0.8 Paint System Water Content 0.6 0.4 0.2 0 0 5 10 15 20 25 30 35 40 Time (hours)
Radiation Intensity (W/m 2 @340) nm or Water On/Off SAE J2527 Cycles 1 Water 0.75 0.5 UV 0.25 0 0 100 200 300 400 500 600 700 800 Time (minutes)
Irradiance (W/m2 @340nm) or Water Spray On/Off Developmental Weathering Cycle 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Irradiance Water 0 500 1000 1500 2000 2500 3000 Time (minutes)
Radiation Intensity (W/m 2 @340) nm or Water On/Off SAE J2527 Cycles 1 0.75 0.5 0.25 UV 0 0 500 1000 1500 2000 2500 3000 Time (minutes)
Irradiance (W/m2 @340nm) or Water Spray On/Off Rarely Rains when the Sun is Shining 1 0.9 0.8 Gradual Dawn 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Irradiance Water 0 500 1000 1500 2000 2500 3000 Time (minutes)
Irradiance (W/m2 @340nm) or Water Spray On/Off Stresses Required for Cracking 1 0.9 0.8 Irradiance Water 0.7 0.6 0.5 Cyclic Stresses (cracking) Surface Erosion (gloss) 0.4 0.3 0.2 0.1 0 Irradiance Water 0 500 1000 1500 2000 2500 3000 Time (minutes)
Irradiance (W/m2 @340nm) or Water Spray On/Off Deep Water Penetration for Blistering/Delamination 1 0.9 0.8 0.7 0.6 0.5 Deep Water Penetration adhesion, blistering, diffusion of small molecules 0.4 0.3 0.2 0.1 0 0 500 1000 1500 2000 2500 3000 Time (minutes)
Failure Modes: Accelerated vs. Florida Exposure Cracking correctly reproduced Gloss loss correctly reproduced Blistering correctly reproduced Adhesion loss mostly reproduced correctly reproduced after further investigation Sample variability was root cause
Paint Systems Tested Automotive ~20 systems, multiple colors All systems were BC/CC Fortified and unfortified Positive controls and known Florida exposure failure mechanisms Selected from 106 specimens exposed in FL Aerospace Four systems, two colors (blue and white) Two monocoat systems, two BC/CC systems Florida, and in-service performance known
Photooxidation of Paint Systems Sample 13 3.00 2.50 D(-OH,-NH)/-CH 2.00 1.50 New Protocol J2527 Boro/Boro 1.00 0.50 Florida 13F (QH) 13F (AH) 13BF (QH) 13BF (AH) 13AT (AH) 13BG (J) Florida 0.00 0 1000 2000 3000 4000 5000 6000 7000 8000 Dosage (kj)
System 13 Florida Exposure J2527 New Protocol Slight BC/E-coat pick-off on Florida and New Protocol Expected Failure Mode: Slight BC/E-coat pick off.
D(-OH,-NH)/-CH Photooxidation of Paint Systems Sample 25 3.00 2.50 J2527 Boro/Boro 2.00 1.50 New Protocol 1.00 0.50 Florida 25F (QH) 25F (AH) 25BF (QH) 25BF (AH) 25AT (AH) 25BG (J) Florida 0.00 0 1000 2000 3000 4000 5000 6000 7000 8000 Dosage (kj)
System 25 Florida Exposure J2527 New Protocol BC/E delamination on Florida pick off on New Protocol Expected Failure Mode: BC/E-coat delamination.
High magnification of Panel 25 Note: micro-delamination spots on Florida and New Protocol Florida New Protocol J2527
D(-OH,-NH)/-CH Photooxidation of Paint Systems Sample 97 3.00 2.50 J2527 Boro/Boro New Protocol 2.00 1.50 1.00 0.50 Florida 97F (QH) 97F (AH) 97BF (QH) 97BF (AH) 97AT (AH) 97BG (J) Florida 0.00 0 1000 2000 3000 4000 5000 6000 7000 8000 Dosage (kj)
System 97 Florida Exposure J2527 New Protocol Gloss, and adhesion loss seen on all panels. Blistering on New Protocol mimics that seen on Florida Expected Failure Mode: Blistering, gloss loss, adhesion loss.
System 103 Florida Exposure J2527 New Protocol Gloss, and adhesion loss seen on all panels. Blistering on New Protocol mimics that seen on Florida Expected Failure Mode: Blistering, gloss loss, adhesion loss.
Photooxidation of Paint Systems Sample 86 3.00 2.50 2.00 D(-OH,-NH)/-CH 1.50 86F (QH) 1.00 86F (AH) 86BF (QH) 0.50 New Protocol J2527 Boro/Boro 86BF (AH) 86AT (AH) 86BG (J) Florida Florida 0.00 0 1000 2000 3000 4000 5000 6000 7000 8000 Dosage (kj)
System 86 Florida Exposure J2527 New Protocol Excellent performance seen on after all tests. Expected Failure Mode: Positive control.
450 490 430 470 410 450 390 430 370 410 350 390 370 330 350 310 330 310 270 290 250 270 290 250 490 470 450 430 410 390 370 350 330 310 250 270 290 Unexposed 0.5 0.45 0.4 0.35 0.3 0.25 absorbance 0.2 0.15 0.1 wavelength 0.05 5 10 15 20 25 30 35 40 45 22 months FL Exposure depth microns 4000 Hours Xenon 0 0.5 0.45 0.4 0.5 Less gradient, more 0.45 uniform loss of UVA 0.4 0.35 0.3 0.25 Absorbance 0.35 0.3 0.25 absorbance 0.2 0.2 0.15 0.15 Wavelength (nm) Peters 0.1 0.05 0 5 10 15 20 25 30 35 40 45 Depth (microns) Wavelength 0.1 0.05 0 5 10 15 20 25 30 35 40 depth microns
Conclusions Correct photo-degradation chemistry can be achieved using new filters in xenon arc weathering chambers. The chemical and physical effects of water during natural weathering can be replicated through the use of longer water sprays during the dark cycle augmented with numerous shorter sprays.
Conclusions A new weathering protocol correctly anticipates all physical failures and is 40% faster than current test method. Introduction of this new weathering protocol will allow for more rapid and more accurate accelerated weathering results.
New Protocol Results Compared to SAE J2527 and Florida - Automotive Physical failures correctly reproduced. Degradation chemistry is correct. Additive effectiveness/loss rate scales correctly. New protocol is as fast as J2527 on a dose basis. New protocol is 40% faster on a time basis
New ASTM D 7869 Requires specimen repositioning in both rotating drum and flat arrays Defines a minimum amount of water required to reach the specimens Sponge Test
New ASTM D 7869 Most accurately defined optical filter in any standard First standard where reasoning behind each step is defined
Conclusions 340nm Black Panel Chamber Air Relative Step Step Irradiance Temperature Temperature Humidity Time 1: Dark + Spray - - - - - - 40 C 95% 5:00 2: Light 0.4 50 C 40 C 50% 1:00 3: Light 0.8 70 C 48 C 35% 13:00 4: Dark - - - - - - 40 C 50% 0:30 5: Dark + Spray - - - - - - 40 C 95% 4:30 Subcycle - Steps 6 to 9 repeat 8 times 6: Dark + Spray - - - - - - 40 C 95% 0:30 7: Light 0.4 50 C 40 C 95% 0:20 8: Light 0.8 70 C 48 C 55% 2:00 9: Dark - - - - - - 40 C 50% 0:10 10: Go To Step 1
Questions? Thank you for the opportunity to present our findings Jeffrey Quill Director of Technical Applications Info@q-lab.com
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