1、Designation: D 2454 95 (Reapproved 2002)Standard Practice forDetermining the Effect of Overbaking on Organic Coatings1This standard is issued under the fixed designation D 2454; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear of last 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 practice covers the determination of the time-temperature effect of overbaking on the physical and chemic
3、alproperties of organic coatings.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of whoever uses this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of regulat
4、ory limitations prior to use.Specific hazard statements are given in Section 7.2. Referenced Documents2.1 ASTM Standards:D 522 Test Methods for Mandrel Bend Test of AttachedOrganic Coatings2D 523 Test Method for Specular Gloss2D 609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Pai
5、nt, Varnish, Conversion Coatings, andRelated Coating Products2D 823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test Panels2D 1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using Micrometers2D 1186 Test Methods for Nondest
6、ructive Measurement ofDry Film Thickness of Nonmagnetic Coatings Applied toa Ferrous Base2D 1308 Test Method for Effect of Household Chemicals onClear and Pigmented Organic Finishes3D 1400 Test Method for Nondestructive Measurement ofDry Film Thickness of Nonconductive Coatings Applied toa Nonferrou
7、s Metal Base2D 1640 Test Methods for Drying, Curing, or Film Forma-tion of Organic Coatings at Room Temperature2D 1729 Practice for Visual Appraisal of Colors and ColorDifferences of Diffusely-Illuminated Opaque Materials2D 1730 Practices for Preparation of Aluminum andAluminum-Alloy Surfaces for Pa
8、inting4D 1731 Practices for Preparation of Hot-Dip AluminumSurfaces for Painting4D 2092 Guide for Preparation of Zinc-Coated (Galvanized)Steel Surfaces for Painting3D 2197 Test Method for Adhesion of Organic Coatings byScrape Adhesion2D 2201 Practice for Preparation of Zinc-Coated and Zinc-Alloy-Coa
9、ted Steel Panels for Testing Paint and RelatedCoating Products2D 2244 Test Method for Calculation of Color DifferencesFrom Instrumentally Measured Color Coordinates2D 2794 Test Method for Resistance of Organic Coatings tothe Effects of Rapid Deformation (Impact)2D 3359 Test Methods for Measuring Adh
10、esion by TapeTest2D 3363 Test Method for Film Hardness by Pencil Test2E 805 Practice for Identification of Instrumental Methods ofColor or Color-Difference Measurement of Materials23. Terminology3.1 Definition:3.1.1 overbakingan exposure of the coating to a moder-ately higher temperature or to a lon
11、ger period of baking, orboth, than recommended by the manufacturer of the coating fornormal curing. This condition is in contrast to “heat resistance”which is a parameter relating to the service life of a coating.4. Summary of Practice4.1 Four panels are prepared and baked at the schedulenormally re
12、commended for the coating. Two of the panels arethen removed and the remaining two are subjected to anadditional overbake in which the time and temperature aremutually agreed upon between the purchaser and the seller.The sets of panels, after a suitable conditioning interval, arethen evaluated for t
13、he properties that are compatible with thesubstrate. Among these are gloss, color, flexibility, adhesion,impact resistance, and resistance to reagents. Note that glasssubstrates should not be tested for impact, and zinc-coatedsubstrates can influence both flexibility and impact.5. Significance and U
14、se5.1 Most coatings are designed for a specific baking time1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.27 on Accelerated Testing.Current edition approved Nov. 10, 1995. Pu
15、blished January 1996. Originallypublished as D 2454 66 T. Last previous edition D 2454 91.2Annual Book of ASTM Standards, Vol 06.01.3Annual Book of ASTM Standards, Vol 06.02.4Annual Book of ASTM Standards, Vol 02.05.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken
16、, PA 19428-2959, United States.and temperature. For a variety of reasons (line stoppages,rerouting back through ovens, oven overheating, etc.) theprescribed time or temperature, or both, of the bake is oftenexceeded. This practice has been found to be useful inevaluating the effects of overbakes on
17、coatings.6. Materials6.1 Standard Baking-Type Coating mutually agreed uponbetween the purchaser and the seller.7. Hazards7.1 The flash points of most solvents used in many organiccoatings and related products are low enough that adequateventilation is needed to avoid exceeding 25 % of the lowerexplo
18、sive limits of the solvents when test panels are beingprepared and baked. As these materials are considered toxic,take care to avoid inhalation of solvent vapor and unnecessarycontact of solvent with the skin.8. Procedure8.1 Application of Organic Coating:8.1.1 Apply coatings to steel panels prepare
19、d in accordancewith Practice D 609.8.1.2 Apply coatings to zinc-coated surfaces prepared inaccordance with Guide D 2092, when zinc has been applied bythe hot-dip method or by electroplating.8.1.3 Apply coatings to nonpassivated galvanized steelprepared in accordance with Practice D 2201, when the zi
20、nc isapplied by a continuous galvanizing method using analuminum-bearing zinc.8.1.4 Apply coatings to aluminum surfaces on all-aluminummaterials prepared in accordance with Practices D 1730.8.1.5 Apply coatings to hot-dip aluminum coated surfacesprepared in accordance with Practices D 1731.8.1.6 In
21、cases where a primer is used in practice under thetopcoat, apply the entire system to the panels. The filmthickness of each coat shall be mutually agreed upon betweenthe purchaser and seller, but, in the absence of such agreement,the total thickness shall be 2 6 0.2 mils (50 6 5 m).8.1.7 In instance
22、s where clear coatings are to be tested, theymay be applied to aluminum or white carrara glass, one side ofwhich has been polished to a smooth, high-gloss finish. Otherselected substrata previously agreed upon between the pur-chaser and the seller may also be used. In the absence of aspecific agreem
23、ent between the purchaser and the seller inregard to film thickness, apply the coatings by automatic spray.(Refer to Practices D 823, Method A) at a dry film thickness of2 6 0.2 mils (50 6 5 m). Multiple coats may be used to obtainthis film thickness where necessary due to the nature of thecoating m
24、aterial (Note 1). Manual spray application or thedrawdown method with wire-wound draw bars may be usedwhen automatic equipment is not available.NOTE 1Dry film thickness should be measured in accordance withTest Methods D 1005, D 1186, or D 1400, whichever is applicable. Theadhesion, flexibility, and
25、 color can vary considerably with thickness.8.2 Baking:8.2.1 The baking schedule for each coating includingprimer, topcoat, and primer/topcoat systems shall be mutuallyagreed upon between the purchaser and the seller and shallinclude the following:8.2.1.1 Normal Baking Schedule (Time and Temperature
26、)recommended for the development of optimum film properties,and8.2.1.2 Overbaking CycleThis cycle shall be within prac-tical limits in order to simulate conditions that might beencountered in actual production where baking oven or con-veyor lines, or both might malfunction temporarily due tomechanic
27、al or electrical failure.8.3 Prepare four panels of each coating or coating systemand bake them at the schedule normally recommended toobtain optimum properties. Conduct the baking of these panelsin a mechanical recirculating air oven set to 62F (61C) ofthe specified baking temperature. At the end o
28、f the specifiedtime remove two panels from the oven and subject theremaining two to the overbake cycle by:8.3.1 A continuation of the normal bake but for a previouslyagreed upon time, for example, 50 or 100 % increase in time,or8.3.2 Resetting the oven temperature to the agreed overbaketemperature a
29、nd then continuing the bake for a specified periodof time after the overbake temperature has been reached, orremoving the panels until the overbake temperature is reachedand then baking them for the agreed upon time.NOTE 2The conditions described in 8.3.2 are not usually reproduciblebetween laborato
30、ries or different ovens because of variations in theheating characteristics of ovens.8.3.3 After the sets of panels have been baked according tothe mutually agreed upon baking cycles, place them in asuitable rack and condition for 24 h at 73.5 6 3.5F (23 6 2C)and 506 5 % relative humidity (see Test
31、Methods D 1640)prior to testing. Other conditioning terms may be agreed uponbetween the purchaser and the seller.9. Test Methods9.1 Determine the properties of both sets of panels inaccordance with any or all of the following ASTM methods:9.1.1 GlossTest Method D 523.9.1.2 ColorPractice D 1729 (Visu
32、al), Practice E 805 (in-strumental), or Test Method D 2244.9.1.3 FlexibilityTest Methods D 522 (conical mandreland cylindrical mandrel).9.1.3.1 Heat-aged flexibility values should be determined inaccordance with a baking cycle that is in agreement betweenthe purchaser and the seller.9.1.4 AdhesionTe
33、st Methods D 21975(mechanical) orD 3359 (tape), or both.9.1.5 Impact ResistanceTest Method D 2794.69.1.6 HardnessTest Method D 3363 (pencil test).9.1.7 Exposure to ReagentsIf this test is desired, thechoice of materials to which the coating is to be exposed shallbe governed by the ultimate use of th
34、e coating and shall beagreed upon between the purchaser and the seller. The general5This test method has been found to be inapplicable for powder coatings.6It is suggested that impact resistance be determined by use of the GardnerVariable Impact Tester obtainable from the Gardner Laboratory, Inc., B
35、ethesda, MD.D 24542procedure to be followed in this test is given in Test MethodD 1308.9.1.8 Other tests agreed upon between the purchaser and theseller.10. Report10.1 Report the following information:10.1.1 Substrate employed, including type and thickness,10.1.2 Type of coating,10.1.3 Film thicknes
36、s, including primer, if any,10.1.4 Normal bake schedule, or schedules,10.1.5 Overbake cycle,10.1.6 Test methods employed, and10.1.7 Values determined, including the measured changesbetween the normal and overbake cycles.ASTM International takes no position respecting the validity of any patent right
37、s 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 the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any t
38、ime 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 of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will
39、 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 shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM
40、 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).D 24543
