1、Designation: D 6531 00 (Reapproved 2005)Standard Test Method forRelative Tinting Strength of Aqueous Ink Systems byInstrumental Measurement1This standard is issued under the fixed designation D 6531; the number immediately following the designation indicates the year oforiginal adoption or, in the c
2、ase of revision, the year 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 test method covers the procedure for determiningthe relative tinting strength of wa
3、terbased ink systems using acomputer-aided spectrophotometer.1.2 This test method is applicable to waterbased printinginks and bases to be used primarily in flexographic and gravureprinting applications.1.3 This test method applies only to single, non-fluorescentpigmented colors and black ink system
4、s for which there is areference standard containing a pigment of the identical colorindex name and number.1.4 The procedure in this test method specifies placingtinted samples in a cuvette for spectrophotometric measure-ments. The use of thick wet drawdowns as in Test MethodsD 2066 are inappropriate
5、 due to severe floating problems withaqueous systems.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsi
6、bility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations.2. Referenced Documents2.1 ASTM Standards:2D 2066 Test Methods for Relative Tinting Strength ofPaste-Type Printing Ink DispersionsD 2244 Practice for C
7、alculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 1331 Test Method for Reflectance Factor and Color bySpectrophotometry Using Hemispherical GeometryE 1347
8、 Test Method for Color and Color-Difference Mea-surement by Tristimulus (Filter) ColorimetryE 1349 Test Method for Reflectance Factor and Color bySpectrophotometry Using Bidirectional (45:0 or 0:45)Geometry3. Terminology3.1 Definitions related to color differences are covered inPractice D 2244. The
9、definitions of tinting strength terms aregiven in Test Methods D 2066.4. Summary of Test Method4.1 A standard and unknown samples are each reduced tothe same concentration in a white tinting base then dispersedon a paint shaker.4.2 The dispersed samples are transferred to cuvettes forreflectance mea
10、surements on a spectrophotometer. Hue andstrength relative to the standard tint are computed.NOTE 1The hue readings indicate the closeness of the unknownsample to that of the standard.5. Significance and Use5.1 Tinting strength is an essential property of printing inkdispersions. Although results on
11、 bulk tints do not guaranteeequivalency of dry printed films, they provide useful param-eters for quality control of production batches of bases andfinished inks. Test results may also be used for color matchingpurposes.6. Apparatus6.1 Glass Jars, capacity approx. 64 g, 33 mm in diameter by70 mm in
12、height, with screw cap lids.6.2 Paint Shaker.6.3 Spectrophotometer, with small-area view (10-mm aper-ture, diffuse/8 geometry) and with a computer and software tomeasure reflectance factor, calculate color differences byCIELAB 1976 equation. Tinting strength is calculated by a1This test method is un
13、der the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, andApplications and is the direct responsibility ofSubcommittee D01.56 on Printing Inks.Current edition approved Sept. 1, 2005. Published September 2005. Originallyapproved in 2000. Last previous edition approved in
14、2000 as D 6531 00.2For 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.1Copyright ASTM International, 100 Barr Har
15、bor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Kubelka-Monk equation transformed from the lowest tristimu-lus value. Alternate instrumentation and software may be usedby agreement between producer and user, or different plantlocations.6.4 Disposable Cuvettes, 10 mm in diamet
16、er, with at leastone optically true face.6.5 Disposable Pipettes 7-mL capacity, 3.5-mL bulb drawor suitable substitute.6.6 Balance, capacity 100 g, accurate to 10 mg, preferably1 mg.6.7 Black Electrical Tape.6.8 Black Cover, 90 mm in diameter such as 1-lb ink can,with interior painted flat black.6.9
17、 Ink Knives, small.6.10 Medicine Droppers.7. Materials7.1 Standard Ink or BaseThe standard should be 100 %intended strength of the same pigmentation and similar inviscosity to the unknown sample.7.2 White Tinting Base, compatible with and of a viscositysimilar to samples being tested.8. Sampling8.1
18、Carefully select a sample that is free of skin and othercontamination. The minimum sample per test is 1.0 g of ink, or0.5 g of base.8.2 When ready to conduct the test, remove enough samplefor the test then reseal the container.9. Preparation of TintsNOTE 2Work quickly, as volatile loss during tint p
19、reparation may biastest results.9.1 Weigh approximately 25 g 6 1 g of white tinting baseand put into the jar. Record the weight to two decimal places.Coat the sides of the jar with the tinting base.9.2 Put the lid on the jar then tip and rotate the jar so that thesides are completely covered with th
20、e tinting base.9.3 Using a medicine dropper, weigh approximately 1 g 60.1 g of the unknown ink or 0.5 g 6 0.1g of test base into thejar. Record weight to two decimal points.9.4 Divide exact weight of ink by 0.02. The resultingnumber represents the total weight of sample plus tinting basefor a 2 % ti
21、nt. Add tinting base accordingly. If the sample is abase, divide the exact weight by 0.01. Add tinting baseaccordingly to make a 1 % tint. In both cases, total weightshould be approximately 50 g. The amount of colorant shouldbe adjusted so that, at the wavelength of calculation, thereflectance is ap
22、proximately 0.40.9.5 Place cap on jar and close tightly.9.6 Repeat 9.1-9.5 with the standard ink or base.9.7 Securely position the samples in the paint shaker.Position the samples at the leading edge of the shaker to get themost vigorous shaking action.9.8 Shake sample jars for five minutes.9.9 Stop
23、 the paint shaker and invert the sample jars. Shakefor another five minutes.9.10 Visually check the jars to make sure that the tints areuniform with no white remaining, especially in the corners ofthe jar. If any white remains, repeat 9.8 until it is completelymixed.9.11 Let the samples sit for five
24、 minutes so the air bubblescan dissipate.10. Procedure for Spectrophotometric Measurements10.1 Calibrate the spectrophotometer with D65 light source,10 observer, and specular component included. (See 10.9.)10.2 Referring to the manual of the software that is beingused, set the computer to measure th
25、e reflectance of thestandard sample.10.3 Remove port cover and center an empty cuvette overthe port with the optically true side facing the light source.Tape it in place using the black electrical tape.10.4 Open the tint of standard sample and stir it with adisposable pipet to insure homogeneity. Fi
26、ll the pipet with thetint.10.5 Touch the tip of the pipet to the inside surface of thecuvette that the spectrophotometer will read, and fill thecuvette to above the level of the spectrophotometer port in onecontinuous motion. If it is not, the specimen will not readproperly.10.6 Attach the port cove
27、r to the front of the spectropho-tometer and place the black cover over the cuvette on the port.10.7 Take reflectance factor readings of the standard tint atspectral measurements of 20 nm or smaller intervals.10.8 Remove cuvette from the sample port.10.9 Repeat 10.1-10.8 with the unknown tint sample
28、.10.10 Alternatively, measure the CIE tristimulus values ofthe specimen on a spectrophotometer or tristimulus colorimeterin accordance with Test Method E 1331, Test Method E 1347or Test Method E 1349. Make measurements as in 10.3-10.8.Ifhemispherical geometry is used, the specular components maybe e
29、ither included or excluded as long as the same condition isconsistently used. The tristimulus values may be based on theCIE 1964 (10) supplementary standard observer and standardilluminant D65 or the CIE 1931 (2) standard observer andstandard illuminant C, as long as the same basis is consistentlyus
30、ed. Record in decimal units the lowest appropriate value(two decimal points), for instance, X with blue colors, Y withreds, blacks and whites or Z with yellows.11. Calculation11.1 Referring to the software manual, obtain the computerdetermined CIELAB values (L*a*b*h) for the tint of thestandard ink
31、or standard base, and the unknown ink orunknown base.11.2 Calculate the shade difference between the two tints(DL*, Da*, Dc* and Dh).11.3 Calculate the tinting strength of the unknown accord-ing to the Kubelka-Munk equation as follows:TS,%51 2 R!2/2R u1 2 R!2/2Rs3 100 (1)where:D 6531 00 (2005)2R = s
32、pectral reflectance factor, expressed as a decimalfraction or by mutual agreement, an appropriatetristimulus value.NOTE 3The term (1 R)2/2R represents K/S of the colorant,where K is the absorption coefficient and S is the scattering coefficient,both of which are specific to a colorant. The equation
33、is reported to workbest when the tristimulus value of the tints is about 0.40 and the tintingstrength of the unknown is within 10 % of the standard.12. Precision and Bias12.1 PrecisionAn interlaboratory study was conducted inwhich five laboratories tested in triplicate, three aqueous inksversus stan
34、dard aqueous ink.3The round robin data wereanalyzed according to Practice E 691. The strength varied from90 to 107 %. There was one outlier. The within-laboratory-pooled standard deviation was 1.66 % at 6 df, and the between-laboratories pooled standard deviation was 3.02 % at 9 df.Based on these st
35、andard deviations, the following criteriashould be used for judging the acceptability of results at the95 % confidence level:12.1.1 RepeatabilityTwo results, each the mean of threeresults obtained by one operator should be considered suspectif they differ by more than 4.74 % of value measured.12.1.2
36、 ReproducibilityTwo results, each the mean of threeresults obtained by operators in different laboratories should beconsidered suspect if they differ by more than 7.90 % of valuemeasured.12.2 BiasNo statement on bias can be made because nosuitable reference material exists for determining bias.13. K
37、eywords13.1 aqueous printing inks; colorimeter; Kubelka-Munkequation; printing inks; spectrophotometer; tinting strength;waterbased ink systemsASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of th
38、is 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 time by the responsible technical committee and must be reviewed every five ye
39、ars 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 receive careful consideration at a meeting of theresponsible technical commi
40、ttee, 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 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 194
41、28-2959,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).3Many commercially available white lat
42、ex paints were investigated. Recom-mended for its combination of appropriate properties in order to get the results usedin this test method, is Sherwin Williams “SuperPaint” Interior Latex Flat White WallPaint (X3056-99993), Titanium Dioxide (Type III) = 25 %, Silicates = 12 %). If youare aware of alternative suppliers, that would produce the same results, pleaseprovide this information to ASTM International Headquarters. Your comments willreceive careful consideration at a meeting of the responsible technical committee,1which you may attend.D 6531 00 (2005)3
