1、Designation: D4584 05 (Reapproved 2015)Standard Test Method forMeasuring Apparent pH of Electrocoat Baths1This standard is issued under the fixed designation D4584; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. 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 test method covers the measurement of the freehydrogen ion concentration of electrocoat baths and theirultrafiltrates.1
3、.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.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 this standard to establish appro
4、-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD1293 Test Methods for pH of WaterE70 Test Method for pH of Aqueous Solutions With theGlass ElectrodeE180 Practi
5、ce for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals (Withdrawn 2009)33. Summary of Test Method3.1 A specimen of a well-agitated electrocoat bath is placedin a stirrer-equipped container and the pH measured with a pHmeter and associated glas
6、s and reference electrodes.4. Significance and Use4.1 The pH is the measure of the free hydrogen ionconcentration of a sample, and it indicates whether an electro-coat bath is acidic, neutral, or basic. Since pH measurements ofgood precision are made in aqueous solutions, it is suggestedthat the pH
7、measurements of electrocoat baths are onlysemi-quantitative, and therefore such measurements should bereferred to as apparent pH measurements.4.2 The pH of electrocoat paints is used for research,production, and quality control or electrocoat bath processcontrol.4.3 Other related methods for determi
8、ning the pH of wateror aqueous systems are described in Test Methods D1293 andE70.5. Apparatus5.1 pH Meter,5.2 Glass and Reference Electrodes.NOTE 1Due to the polarity of electrocoat materials it is desirable touse a separate set of electrodes for each bath polarity, cathodic and anodic,because a ba
9、th of opposite polarity poisons the electrodes. A desiredpractice is to rinse the electrodes after each measurement with anappropriate solvent for the electrocoat material.5.3 Thermometer, capable of 0.5C accuracy with a 2 to32C range.6. Reagents6.1 Reference Standard Solutions, commercial standards
10、 ofpH 4.0, 7.0, and 10.0.6.2 Purity of WaterReferences to water shall be under-stood to mean water conforming to Type II of SpecificationD1193.7. Sampling and Sample Preparation7.1 The sample should be obtained while the electrocoatbath is under proper circulation so that a uniform material isobtain
11、ed. In case of an ultrafiltrate, the material should bethoroughly mixed or stirred prior to sampling to assureuniformity.7.2 After sampling and prior to removing a test specimen itis mandatory that the sample be shaken or stirred until it ishomogeneous and free of any settled material. This is parti
12、cu-larly important if there is any delay between the sampling ofthe bath and the preparation of the specimens for the test. Theabsence of settled material can be ascertained visually (in atransparent container) or by inserting a spatula, scraping the1This test method is under the jurisdiction of AST
13、M Committee D01 on Paintand Related Coatings, Materials, and Applicationsand is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved June 1, 2015. Published June 2015. Originallyapproved in 1986. Last previous edition approved in
14、 2010 as D4584 05 (2010).DOI: 10.1520/D4584-05R15.2For referenced ASTM standards, visit 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.3The last a
15、pproved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1bottom of the container to make sure that there is no settledmatter. Shake or stir the samples until specimens ar
16、e taken formeasurement; this point is very important.8. Procedure8.1 StandardizationTurn on the pH meter and allow it towarm up. Wash the electrodes with a stream of water. Use thepH meter manufacturers instructions to calibrate the elec-trodes with buffer solutions of pH 4 and 7 for cationic system
17、sand 7 and 10 for anionic systems. Rinsing the electrodesthoroughly after each calibration. The reference buffer solu-tions should thoroughly match the temperature of the samplesto be measured within 2C.8.2 Apparent pH Measurement:8.2.1 Place a suitable quantity of a well-mixed electrocoatspecimen i
18、n a clean and dry container equipped with a stirrer(preferably magnetic). Operate the stirrer fast enough to avoidseparation of the paint but slow enough to prevent splashing orvortexing. Allow the temperature of the specimen to come toequilibrium (that is, the temperature should show a drift of les
19、sthan 0.5C/min). Record the temperature, and dial in thetemperature correction on the pH meter. Place the electrodes inthe specimen and determine the pH value in accordance withthe pH meter manufacturers instructions. Record the pH valueand the temperature of the specimen.8.2.2 Run two successive sp
20、ecimens of the electrocoat bathsample; the pH value should be within 0.1 units/min andshould show drifts of less than 0.1 units/min. If these driftlimits are not met, check the pH meter and repeat the wholeprocedure.9. Precision and Bias9.1 In an interlaboratory study of the test method, with fivela
21、boratories measuring five electrocoat bath samples with pHranging from 2.6 to 8.0, the intralaboratory standard deviation(in accordance with Practice E180) was found to be 0.03 unitsat 25 df, and the interlaboratory coefficient of variation was0.08 units at 20 df. Based on these standard deviations,
22、 thefollowing criteria should be used for judging the acceptabilityof results at the 95 % confidence level:9.1.1 RepeatabilityTwo results, each the mean of dupli-cate determinations, obtained by the same operator on differentdays should be considered suspect if they differ by more than0.1 units.9.1.
23、2 ReproducibilityTwo results, each the mean of dupli-cate determinations, obtained by operators in different labora-tories should be considered suspect if they differ by more than0.3 units.9.1.3 BiasBias cannot be determined for this methodbecause there are no accepted standards for the free hydroge
24、nion content of electrocoat baths and their ultrafiltrates.10. Keywords10.1 electrocoat baths; pH; pH measurement; ultrafiltratesASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard ar
25、e 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 time by the responsible technical committee and must be reviewed every five years andif not
26、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 receive careful consideration at a meeting of theresponsible technical committee, which yo
27、u 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 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United
28、 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 Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 05 (2015)2
