1、Designation: D 6900 03Standard Test Method forWet Adhesion of Latex Paints to a Gloss Alkyd EnamelSubstrate1This standard is issued under the fixed designation D 6900; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 a
3、fter 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 o
4、f this 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:D 523 Test Method for Specular Gloss2D 714 Test Method for Evaluating Degree of Blistering ofPaints2D 2486 Test Meth
5、ods for Scrub Resistance of Wall Paints2D 3924 Specification for Standard Environment for Condi-tioning and Testing Paint, Varnish, Lacquers, and RelatedMaterials23. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 wet adhesion, nthe ability of a coating to resistremoval by scrubb
6、ing 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, are 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
7、.4.2 The drawdown films are allowed to dry under standard-ized conditions. Then, eighteen cuts are made to form a 6 by 10cut block, creating sixty 6.4 mm (0.25 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 mounte
8、d 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 arecompletely removed.5. Significance and Use5.1 After application to either interior or exterior surfaces,latex paints may be subjected to conditions
9、 of high humidity,condensation, or precipitation. This may sometimes lead to aloss of adhesion to the substrate over which they have beenapplied. This method is a quantitative measure of the adhesionof latex paints to glossy substrates under such conditions.6. Apparatus6.1 Constant temperature/humid
10、ity room in accordance withSpecification D 3924 23 6 2C (73.5 6 3.5F) and 50 6 5%relative humidity.6.2 Drawdown Plate.6.3 Straight Line Washability Tester and Accessories, perTest Methods D 2486.6.4 Nylon Bristle Brush and Accessories (nominal weight455 g), having nylon brush bristles in 5/4 pattern
11、 extending 19mm (34 in.) from block (as per Test Methods D 2486).6.5 Dow Film Applicator, having 7-mil (0.18-mm) clear-ance by 5.2-in. (132-mm) width. applicator blade.6.6 Single-edge Razor Blade, in safety holder.6.7 Metal Straight Edge, (or appropriate guide).7. Reagents and Materials7.1 A ready-m
12、ix deep-tint alkyd gloss enamel with a 60gloss of at least 65 as measured in accordance with TestMethod D 523 (or alkyd as agreed upon by the purchaser andsupplier).7.2 Plastic test panels as used in Test Methods D 2486.38. Procedure8.1 Preparation of the Alkyd Substrate PanelsAttach theplastic pane
13、l to the drawdown plate and drawdown the alkyd1This 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 Coatings.Current edition approved May 10, 2003. Published J
14、une 2003.2Annual Book of ASTM Standards, Vol 06.01.3This 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 07430.1Copyright ASTM International,
15、100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.gloss 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, wh
16、ich may affectadhesion.8.1.1 Allow the alkyd gloss enamel to air-dry in a horizontalposition. 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
17、 is allowed to cure for morethan six weeks.8.2 Application and Evaluation of Test 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 fo
18、r application should befairly slow1 to 2 s from edge to edge. Each drawdown ismade 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 variabi
19、lity of results from testto test.8.2.2 Condition the panels for one week in the constanttemperature/humidity room as specified in SpecificationD 3924 or under other conditions agreed upon by buyer andseller. Shorter conditioning times may be used if more stringentmeasures of wet adhesion are needed,
20、 as in the case ofdetermining a coatings “early” wet adhesion.NOTE 2Since humidity 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 an
21、d rinse the scrub brush asspecified in Test Methods D 2486.8.2.4 Using a metal straightedge 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
22、sufficient pressure to cut, but not tear the latexpaint film. (WarningAvoid cutting 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
23、the water and quickly examinethe panel for blistering, per Test Method D 714 (optional).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
24、.7 Observe each test paint to determine its point ofadhesive failure. Record the 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 foreas
25、e of placement, only rate the path of the brush.9. Report9.1 Record any blistering, per Test Method D 714 (op-tional).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
26、 than those specified in this testmethod.9.4 The drying time and conditions used, if 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 Bias10.1 The precision and bias statement is being developed byTask Grou
27、p D01.42.04.11. Keywords11.1 wet adhesionASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and th
28、e riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision o
29、f this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should
30、make your views known to the ASTM Committee on Standards, 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).FIG. 1D6900032
