1、 FORD LABORATORY TEST METHOD AI 103-02 Date Action Revisions 2000 08 07 Editorial no technical change A. Cockman 1995 02 14 Printed copies are uncontrolled Page 1 of 4 Copyright 2000 , Ford Global Technologies, Inc. UVA RETENTION IN CLEARCOATS Application This test method determines the amount of ul
2、traviolet light absorbers (UVA) in clearcoat enamels. UVAs are lost as a function of weathering and can be monitored as a function of exp osure time in a weatherometer or Florida. This information provides a way to evaluate the durability of coatings based on the rate of UVA loss, and should be used
3、 as a comparison tool for modifications to a coating and across coating families. Required Test Equipment Quartz Slides - 10 mm wide to fit standard UV - VIS spectrophotometer sample compartment, approximately 37 mm long X 1 - 2 mm thick Glass Capillary Tubes - for coating quartz slides with clearco
4、at Laboratory Oven - capable of curing coating Soft Foam Pad - for cleaning exposure panels Compressed Air Source - for drying panels after washing Single Edged Razor Blades - for scraping clearcoat off of panels Volumetric Flasks - 25 mL with ground glass joints Glass Stoppers - to fit 25 mL volume
5、tric flask Analytical Balance - capable of measuring to 0.001g Pipettes - 1 - 2 mL disposable glass Filtering Media - Kimwipes EX - L from Kimberly - Clark or equivalent UV Quartz Cuvettes - 10 mm X 10 mm UV-VIS Spectrophotometer System - capable of measuring 250 - 400 nm Materials and Solutions Req
6、uired Methylene Chloride - certified ACS grade or equivalent Mild Soap Solution - for washing Florida panels FORD LABORATORY TEST METHOD AI 103-02 Page 2 of 4 Copyright 2000, Ford Global Technologies, Inc. Method A: - UVA Retention of Clearcoats on Quartz Slides This method is used for determining U
7、VA retention of clearcoat films on quartz slides after weathering. A sufficient number of quartz slides shall be prepared for weathering to satisfy the applicable Engineering Specification. I. Preparation of Coatings on Quartz Slides 1. Collect a UV baseline on the quartz slides prior to coating wit
8、h clearcoat. 2. Using a capillary tube, coat a quartz slide with c learcoat paint containing a UVA. 3. Allow the paint solvent to evaporate. NOTE: The quartz slide must be anchored in the sample compartment in the same orientation each time a measurement is made in order to get consistent results. 4
9、. Observe the UV spectr um of the clearcoat from 450nm to 250nm. a. If the maximum absorbance is in the range specified in the relevant material specification, cure the clearcoat paint on the quartz slide using the recommended temperature and time or as indicated by the applicabl e engineering speci
10、fication. b. If the maximum absorbance is not in the desired range specified in the relevant material specification, remove the uncured clearcoat from the quartz slide by rinsing with methylene chloride. Repeat steps 2 - 4 until the abso rbance is in the recommended range. 5. Observe the UV spectrum
11、 of the clearcoat after cure. a. If the maximum absorbance is still in the desired range, obtain a UV spectrum of the clearcoat from 450 to 250nm before weathering has occurred. b. If the maximu m absorbance has dropped below the minimum of the desired range, the UVA present in the clearcoat is vola
12、tile. The coating and curing process must be repeated until a maximum absorbance in the desired range after cure has been obtained. It is possible to e stimate the degree of volatility from the first preparation and compensate accordingly. 6. Record the absorbance of the baseline. (It may be zero.)
13、7. Record both the wavelen gth and the absorbance of all the maxima observed. 8. If necessary, subtract the baseline absorbance from the absorbance of the maxima to get the corrected absorbance values. These will be called the “time 0“ values. It is necessary to record a “time 0“ sp ectrum for each
14、sample. FORD LABORATORY TEST METHOD AI 103-02 Page 3 of 4 Copyright 2000, Ford Global Technologies, Inc. II. Monitoring UV Retained 1. Remove the quartz slides from exposure at intervals indicated by the applicable Engineering Specification or more frequently as suggested by the ongoing results. Rec
15、ord the hours of exposure upon removal. 2. Obtain and analyze the UV spectrum of a clearcoat using the guidelines presented above. (Place the quartz slides back in the weatherometer as soon as possible to continue weathering. Quartz sli des that have completed Florida exposure need not be sent back.
16、) 3. Also note if the wavelength of the maxima are shifting from the “time 0“ values. 4. Chose a maximum to monitor and plot the data as a function of exposure time. Method B: - UVA Retention of Clearcoats on Basecoat/Clearcoat Systems This method is used for determining the UVA retention of clearco
17、ats on basecoat/clearcoat systems applied to painted panels or parts. To allow for 12 data points of UVA retention versus hours of weathering, prepar e 12 panels for each type of enamel per FLTM BI 103 - 02 for each exposure condition (i.e., 12 panels for weatherometer and 12 panels for Florida). An
18、 appropriate number of retain panels shall be prepared to establish a reliable time 0 UVA content. 1. Prepar e and cure the panels at the time and temperature recommended by the relevant material specification. Age fresh panels for 72 hours at 23 +/ - 2 C. 2. Returned, completed exposure panels from
19、 Florida only should be washed in entirety with a soft foam pad usi ng a mild soap solution. Next the panels are rinsed with tap water and blown dry using clean compressed air. 3. A clean volumetric flask is tared on an analytical balance. 4. The clearcoat is then scraped from the clean panels using
20、 a single edged razor bl ade. All of the clearcoat in one area must be removed before moving onto a new area. Care must be taken not to scrape so far down as to remove the basecoat. 5. Enough clearcoat is transferred to the flask so that approximately 40 60 mg of clearcoat is weighed out. Record the
21、 exact weight, as grams of clearcoat. 6. Methy lene chloride is pipetted into the volumetric so as to fill it up to the meniscus, carefully rinsing down the sides of the volumetric with the solvent. 7. The flask is stoppered and shaken vigorously to ensure proper mixing of the clearcoat and solvent.
22、 8. Allow the flask to sit stoppered for at least 18 hours. 9. After allowing the flask to sit, check the volume of the solution and if any has evaporated, fill again to the meniscus with methylene chloride. FORD LABORATORY TEST METHOD AI 103-02 Page 4 of 4 Copyright 2000, Ford Global Technologies,
23、Inc. 10. Shake the flask to allow for proper dispersion. 11. Collect a UV baseline of the quartz cuvette containing methylene chloride only and record. 12. Empty the cuvette, and allow to dry. 13. Carefully filtering the clearcoat extract solution, using Kimwipes and pipettes as filtering aids, fill
24、 the cuvette as quickly as possible to minimize evaporation. It is essential that this step be done quickly as the methylene chloride is very volatile and the concentration of the filtered solution will be very different from the extract solution if too much time is a llowed to pass. 14. Observe the
25、 UV spectrum of the filtered extract solution from 450 to 250nm. If the maximum absorbance is not between 0.5 - 1.5, Repeat steps 3 - 13, adjusting the amount of clearcoat sampled until the absorbance is in the proper range. 15. Record both the wavelength and the absorbance of all the maxima observe
26、d, including the time 0 panel. 16. If necessary, subtract the baseline absorbance from the absorbance of the maxima of each sample to get the corrected absorbance values. II. Calculating and Monitoring Amount of UVA Retained 1. For analysis of the UV spectrum of the extraction solutions, a maximum m
27、ust be picked and the peak absorbance value obtained. The abs/conc (absorbance/grams/milliliters) value of the extracti on solution is obtained by using the following formula: abs/conc = absorbance maximum (grams of clearcoat/milliliters of solvent) 2. Remove the basecoat/clearcoat panels from expos
28、ure at intervals indicated by the applicable Engineering Specification or more frequently as suggested by the ongoing results. Record the hours of exposure upon removal. 3. Obtain and analyze the UV spectrum of a clearcoat using the guidelines presented above. Also note if the wavelength of the maxi
29、ma are shifting from the “time 0“ values 4. Chose a maximum to monitor and plot the data as a function of exposure time. The loss of UVA can be obtained by plotting the abs/conc values determined from extractions of the exposed samples as a function of exposure time. Chemicals, materia ls, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities.
