1、Designation: D6900 10Standard Test Method forWet Adhesion of Latex Paints to a Gloss Alkyd EnamelSubstrate1This standard is issued under the fixed designation D6900; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This method covers a procedure for measuring byscrubbing the adhesion of latex paints to glossy alkyd enamelsubstrates afte
3、r exposure to wet conditions.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of t
4、his standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D523 Test Method for Specular GlossD714 Test Method for Evaluating Degree of Blistering ofPaintsD2486 Test Methods for
5、 Scrub Resistance of Wall PaintsD3924 Specification for Environment for Conditioning andTesting Paint, Varnish, Lacquer, and Related MaterialsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE177 Practice for Use of the Terms Precision and Bias inASTM T
6、est Methods3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 wet adhesion, nthe ability of a coating to resistremoval by scrubbing from the surface beneath it after expo-sure to wet conditions and abrasion.4. Summary of Test Method4.1 Test paints, with optional control paint, ar
7、e drawn downusing a 7-mil clearance Dow applicator (11 m2/L) across acured alkyd gloss enamel previously drawn down on a black orwhite plastic panel.4.2 The drawdown films are allowed to dry under standard-ized conditions. Then, eighteen cuts are made to forma6by10cut block, creating sixty 6.4 mm (0
8、.25 in) squares, in the centerof each film with a razor blade.4.3 The panels are then soaked for 30 min in ambient tapwater. The panel is mounted in a washability tester and 20 mLof water are applied. The panel is then scrubbed for up to 500cycles or until all of the squares within each block arecom
9、pletely removed.5. Significance and Use5.1 After application to either interior or exterior surfaces,latex paints may be subjected to conditions of high humidity,condensation, or precipitation. This may sometimes lead to aloss of adhesion to the substrate over which they have beenapplied. This metho
10、d is a quantitative measure of the adhesionof latex paints to glossy substrates under such conditions.6. Apparatus6.1 Constant temperature/humidity room in accordance withSpecification D3924 23 6 2C (73.5 6 3.5F) and 50 6 5%relative humidity.6.2 Drawdown Plate.6.3 Straight Line Washability Tester an
11、d Accessories, perTest Methods D2486.6.4 Nylon Bristle Brush and Accessories (nominal weight455 g), having nylon brush bristles in 5/4 pattern extending 19mm (34 in.) from block (as per Test Methods D2486).6.5 Dow Film Applicator, having 7-mil (0.18-mm) clear-ance by 5.2-in. (132-mm) width. applicat
12、or blade.6.6 Single-edge Razor Blade, in safety holder.6.7 Metal Straight Edge, (or appropriate guide).1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.42 on Architectural C
13、oatings.Current edition approved Feb. 1, 2010. Published March 2010. Originallyapproved in 2003. Last previous edition approved in 2003 as D6900 - 03.DOI:10.1520/D6900-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Ann
14、ual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Reagents and Materials7.1 A ready-mix deep-tint alkyd gloss enamel with
15、a 60gloss of at least 65 as measured in accordance with TestMethod D523 (or alkyd as agreed upon by the purchaser andsupplier).7.2 Plastic test panels as used in Test Methods D2486.38. Procedure8.1 Preparation of the Alkyd Substrate PanelsAttach theplastic panel to the drawdown plate and drawdown th
16、e alkydgloss enamel lengthwise using a 7-mil clearance Dow appli-cator. The time for application should be fairly slow3 to 4 sfrom end to end. The drawdown must be free of ridges,holidays, specks, or other imperfections, which may affectadhesion.8.1.1 Allow the alkyd gloss enamel to air-dry in a hor
17、izontalposition.Allow to cure typically for a minimum of three weeks.Panels are to be used between three to six weeks from the dateof preparation. Wet adhesion with some latex paints may bedramatically reduced if the alkyd is allowed to cure for morethan six weeks.8.2 Application and Evaluation of T
18、est Paints:8.2.1 Attach the cured alkyd enamel-coated plastic panel tothe drawdown plate and simultaneously drawdown test paintand an optional control paint side-by-side using the 7-milclearance Dow applicator. The time for application should befairly slow1 to 2 s from edge to edge. Each drawdown is
19、made perpendicular to the length of the panel and positioned sothat the drawdowns are contiguous (See Fig. 1).NOTE 1Typically a control paint of known wet adhesion is recom-mended for use in the method to limit the variability of results from testto test.8.2.2 Condition the panels for one week in th
20、e constanttemperature/humidity room as specified in SpecificationD3924 or under other conditions agreed upon by buyer andseller. Shorter conditioning times may be used if more stringentmeasures of wet adhesion are needed, as in the case ofdetermining a coatings “early” wet adhesion.NOTE 2Since humid
21、ity and temperature both markedly influence therate at which paint dries, a constant temperature/humidity room is stronglyrecommended in order to achieve reproducible results using this method.8.2.3 Condition, break in and rinse the scrub brush asspecified in Test Methods D2486.8.2.4 Using a metal s
22、traightedge or suitable guide, makeeighteen razor blade cuts, spaced 6.4 mm (0.25 in.) apartforminga6by10array with a razor blade in the center of eachpaint (See Fig. 1). Each cut should be made in one steadymotion with sufficient pressure to cut, but not tear the latexpaint film. (WarningAvoid cutt
23、ing completely through thealkyd enamel into the plastic substrate.)8.2.5 Submerge each panel face-up for 30 min in a flatcontainer of ambient tap water, being careful not to bend thesubstrate.8.2.6 Remove the panel from the water and quickly examinethe panel for blistering, per Test Method D714 (opt
24、ional).Immediately secure the panel in the washability tester using thegasketed frame accessory, ensuring that the array is in the pathof the brush. Place 20 mL of water in the path of the brush andstart the machine.8.2.7 Observe each test paint to determine its point ofadhesive failure. Record the
25、number of cycles when 100 %adhesive failure occurs or the percent adhesive failure at 500cycles. If the test paint is not removed within 500 cycles, thetest is terminated. Since the array is larger than the brush forease of placement, only rate the path of the brush.9. Report9.1 Record any blisterin
26、g, per Test Method D714 (optional).9.2 The number of cycles for 100 % adhesive failure orpercent adhesive failure after 500 cycles.9.3 The wet film thickness of the gloss alkyd enamel andlatex test paints if different than those specified in this testmethod.9.4 The drying time and conditions used, i
27、f different thanthose specified in this test method.9.5 Report alkyd used in 7.1.9.6 Report any variation from the test method.10. Precision and Bias410.1 The precision of this test method is based on aninterlaboratory study of Test Method D6900, Standard TestMethod for Wet Adhesion of Latex Paints
28、to a Gloss AlkydEnamel Substrate, conducted in 2007. Results in this studywere obtained from five laboratories, testing six differentpaints. Every “test result” reported represents an individualdetermination. Each participating laboratory reported fourreplicate test results for every material. Excep
29、t for the inclusionof only five laboratories, Practice E691 was followed for thedesign and analysis of the data; the details are given in ASTMResearch Report No. RR:D011148.10.1.1 Repeatability Limit (r)Two test results obtainedwithin one laboratory shall be judged not equivalent if theydiffer by mo
30、re than the “r” value for that material; “r”isthe3This test method was qualified by a round robin using Leneta P-121-10N dullblack plastic panels 612 by 17 in. by 10 mils (165 by 432 by 0.25 mm) in size,obtainable from the Leneta Co., 15 Whitney Rd, Mahwah, NJ 07430.4Supporting data have been filed
31、at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D01-1148.FIG. 1 IllustrationD6900 102interval representing the critical difference between two testresults for the same material, obtained by the same operatorusing the same equipment on the same day in the samela
32、boratory.10.1.1.1 Repeatability limits are listed in Table 1 and Table2.10.1.2 Reproducibility Limit (R)Two test results shall bejudged not equivalent if they differ by more than the “R” valuefor that material; “R” is the interval representing the criticaldifference between two test results for the
33、same material,obtained by different operators using different equipment indifferent laboratories.10.1.2.1 Reproducibility limits are listed in Table 1 andTable 2.10.1.3 The above terms (repeatability limit and reproduc-ibility limit) are used as specified in Practice E177.10.1.4 Any judgment in acco
34、rdance with statements 10.1.1and 10.1.2 would normally have an approximate 95 % prob-ability of being correct, however the precision statistics ob-tained in this ILS must not be treated as exact mathematicalquantities which are applicable to all circumstances and uses.The limited number of materials
35、 tested and laboratories report-ing results guarantees that there will be times when differencesgreater than predicted by the ILS results will arise, sometimeswith considerably greater or smaller frequency than the 95 %probability limit would imply. The repeatability limit and thereproducibility lim
36、it should be considered as general guides,and the associated probability of 95 % as only a roughindicator of what can be expected.10.2 BiasAt the time of the study, there was no acceptedreference material suitable for determining the bias for this testmethod, therefore, no statement on bias is being
37、 made.10.3 The precision statement was determined through sta-tistical examination of 208 results, from four laboratories, onsix materials, and two substrates. Data from one outlier lab wasexcluded from the calculations.11. Keywords11.1 wet adhesionTABLE 1 24 Hour (% failure)Panel PaintAverageAxRepe
38、atabilityStandardDeviationsrReproducibilityStandardDeviationSRRepeatabilityLimitrReproducibilityLimitRGreen AlkydA 0 0.3 0.3 0.7 0.7B 0 0.4 0.4 1.0 1.1C 100 0.0 0.0 0.0 0.0D 0 0.3 0.4 0.7 1.2E 7 0.4 12.3 1.0 34.4F 100 0.0 0.0 0.0 0.0Red AlkydA 0 0.0 0.0 0.0 0.0B 0 0.4 0.4 1.0 1.1C 100 0.0 0.0 0.0 0.
39、0D 0 0.0 0.0 0.0 0.0E 19 24.6 36.6 68.9 102.5F 100 0.0 0.0 0.0 0.0AThe average of the laboratories calculated averages.TABLE 2 7 Day (% failure)Panel PaintAverageAxRepeatabilityStandardDeviationsrReproducibilityStandardDeviationSRRepeatabilityLimitrReproducibilityLimitRGreen AlkydA 0 0.0 0.5 0.0 1.4
40、B 1 0.0 1.0 0.0 2.8C 100 0.0 0.0 0.0 0.0D 0 0.3 0.7 0.7 1.9E 0 0.4 0.8 1.0 2.3F 100 0.0 0.0 0.0 0.0Red AlkydA 0 0.0 0.0 0.0 0.0B 0 0.0 0.0 0.0 0.0C 98 5.0 5.6 14.0 15.7D 0 0.0 0.0 0.0 0.0E 0 0.4 0.4 1.0 1.1F 100 0.0 0.0 0.0 0.0AThe average of the laboratories calculated averages.D6900 103ASTM Intern
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44、ards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D6900 104
