1、Designation: D2698 05 (Reapproved 2010)Standard Test Method forDetermination of the Pigment Content of Solvent-ReduciblePaints by High-Speed Centrifuging1This standard is issued under the fixed designation D2698; the number immediately following the designation indicates the year oforiginal adoption
2、 or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scop
3、e1.1 This test method covers the separation of pigment fromsolvent-reducible paints and the calculation of the percentpigment from the results of nonvolatile determinations on thetotal paint and the separated vehicle.NOTE 1This test method has been proven to be applicable to mostsolvent-reducible pa
4、ints, the exception being those paints containingseverely bleeding pigments or pigments such as carbon black that are verydifficult or impossible to centrifuge.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standar
5、d does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of 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
6、 Standards:2D2369 Test Method for Volatile Content of Coatings3. Significance and Use3.1 This test method describes a rapid method for separatingpigment from solvent-reducible paints.3.2 This test method is used by paint producers and con-sumers for product acceptance and process control.4. Apparatu
7、s4.1 Laboratory Centrifuge, capable of developing 32 000 gor higher.35. Procedure5.1 Shake the sample for 10 min on a mechanical shaker,stir with a paddle to loosen any caked pigment, and shake againfor 10 min. If necessary, repeat until there are no lumps presentand the sample is thoroughly mixed.5
8、.2 Add the mixed paint to the centrifuge container untilsufficient paint is added to permit the recovery of 25 mLminimum of clear vehicle. Revolve the bowl at 32 000 g orhigher for 15 min or until a clear vehicle is obtained.5.3 Transfer the vehicle carefully, so as not to dislodge anyof the pigment
9、 from the walls, into a jar that is immediatelycapped to prevent any solvent losses by evaporation. Use thisvehicle for the determination of the nonvolatile content of theseparated vehicle.6. Percent Paint and Vehicle Solids6.1 Determine the percent nonvolatile content of the origi-nal paint and the
10、 separated vehicle in accordance with TestMethod D2369.7. Calculation7.1 Calculate the weight percent pigment of paint, P,asfollows:P 5 A 2 B! 3 100/100 2 B (1)where:1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the
11、 direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved Dec. 1, 2010. Published December 2010. Originallyapproved in 1965. Last previous edition approved in 2005 as D2698 05. DOI:10.1520/D2698-05R10.2For referenced ASTM standards, visi
12、t the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3A supercentrifuge or a centrifuge equipped with a high-speed head have beenfound satisfactory fo
13、r this purpose. Any centrifuge capable of developing 32 000 gand having facilities for sealing the specimen to prevent solvent loss should alsoprove to be satisfactory.To calculate the gravities developed by a particular centrifuge use the followingcalculation:g=rotating radius, cm 3 r/min23 1.118 3
14、 1051Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.A = nonvolatile content of paint, %, andB = nonvolatile content of separated vehicle, %.8. Recovery of Pigment for Analysis8.1 The pigment may be completely recovered from thecentri
15、fuge bowl and washed to remove residual vehicle. Thismay be done either by a Soxhlet extraction or washing thepigment with a suitable solvent and recentrifuging.NOTE 2It has been noted that the removal of the pigment from thebowl of a Sharples supercentrifuge can be facilitated by lining the bowlwit
16、h a piece of polyester film prior to adding the sample and subsequentlyjust slipping the polyester film along with the pigment out of the bowl.9. Precision and Bias9.1 PrecisionThe precision estimates are based on aninterlaboratory study of this test method in which air dryingmaterials were analyzed
17、 in duplicate or triplicate. The follow-ing criteria should be used for judging the acceptability ofresults at the 95 % confidence level:9.1.1 RepeatabilityThe difference between two results,each the mean of duplicate determinations obtained by thesame operator, will approximate 0.1 % absolute. Two
18、suchvalues should be considered suspect if they differ by more than0.25 % absolute.9.1.2 ReproducibilityThe difference between two results,each the mean of duplicate determinations obtained by opera-tors in different laboratories, will approximate 0.25 % absolute.Two such values should be considered
19、 suspect if they differ bymore than 0.5 % absolute.9.1.3 This precision pertains to air-drying materials. Heat-reactive vehicles will have a repeatability and reproducibilityapproximately twice as large, that is, 0.5 % and 1.0 % absolute.9.1.4 It should be noted that when the solvent content of thet
20、otal paint is very low (15 % or less) the precision of this testmethod will not be satisfactory unless the nonvolatile determi-nation is precise to the second decimal place.9.2 BiasBias cannot be determined for this method be-cause there are no accepted standards for pigment content ofsolvent-reduci
21、ble paints.10. Keywords10.1 high speed centrifuging; pigment content; solvent-reducible paintASTM 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 determinati
22、on 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 time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdr
23、awn. Your comments are invited either for revision of 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
24、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 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single
25、 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/).D2698 05 (2010)2
