1、Designation: D6290 18Standard Test Method forColor Determination of Plastic Pellets1This standard is issued under the fixed designation D6290; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in p
2、arentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method is used for the instrumental measure-ment of the degree of yellowness (or change of degree ofyellowness) under daylight illumina
3、tion of homogeneous,nonfluorescent, nearly-colorless transparent or nearly-whitetranslucent or opaque plastics. The measurement is made onpellets and based on tristimulus values obtained with a spec-trophotometer or colorimeter.1.2 This test method is applicable to the color analysis ofplastic pelle
4、ts. It is possible that each material will have uniquecharacteristics that determine the color values.1.3 This procedure outlines a method to determine colormeasurements, such as Yellowness Index (YI), CIE X, Y, Z,and Hunter L, a, b, or CIE L*, a*, b*.1.4 The values stated in SI units are to be rega
5、rded as thestandard. The values given in parentheses are for informationonly.1.5 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-priate safety, health, and environmental prac
6、tices and deter-mine the applicability of regulatory limitations prior to use.NOTE 1This standard and ISO 17223 address the same subject matterbut differ in technical content.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization e
7、stablished in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD2244 Practice for Cal
8、culation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesE179 Guide for Selection of Geometric Conditions forMeasurement of Reflection and Transmission Propertiesof MaterialsE284 Terminology of AppearanceE308 Practice for Computing the Colors of Objects by Using
9、the CIE SystemE313 Practice for Calculating Yellowness and WhitenessIndices from Instrumentally Measured Color CoordinatesE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1331 Test Method for Reflectan
10、ce Factor and Color bySpectrophotometry Using Hemispherical GeometryE1347 Test Method for Color and Color-Difference Mea-surement by Tristimulus ColorimetryE1349 Test Method for Reflectance Factor and Color bySpectrophotometry Using Bidirectional (45:0 or 0:45)GeometryE2935 Practice for Conducting E
11、quivalence Testing inLaboratory Applications2.2 ISO/IEC Standards:ISO 17223 Plastics Determination of Yellowness Index andChange in Yellowness Index.CIE Standard D 001 Colorimetric Illuminants and Observers(Disk) (www.cie.co.at)3. Terminology3.1 DefinitionsRefer to Terminologies D883 and E284 fordef
12、initions of terms used in this test method.4. Significance and Use4.1 Before proceeding with this test method, refer to thespecification of the material being tested. Any test specimenpreparation, conditioning, dimensions, or testing parameters, ora combination thereof, covered in the materials spec
13、ificationshall take precedence over those mentioned in this test method.If there are no material specifications, then default conditionsapply.NOTE 2Some materials, such as polyamide (nylon), can be cooledvery differently during the production of the pellets. This variation in thecooling of the pelle
14、ts can result in different levels of crystallinity in the1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.40 on Optical Properties.Current edition approved Oct. 1, 2018. Published October 2018. Originallyapproved in 199
15、8. Last previous edition approved in 2013 as D6290 - 13. DOI:10.1520/D6290-18.2For 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 on
16、the ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on sta
17、ndardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1pellets only. More crystalline nylons will be more opaque than amorphousnylons. This wi
18、ll result in differences in pellet opacity. The pellet shape isindependent of the crystallinity of the material. This variation in pelletappearance, due to varying levels of crystallinity, does not affect finalproperties.NOTE 3This test method should not be used for general materialspecifications.4.
19、2 This test method describes a technique useful for mak-ing color comparisons of resins in pellet form that is fast andconvenient as it does not require preparation, such as moldingor extruding specimens. The test method shall be used only tocompare specimens of similar pellet shape, size, texture,
20、anddegree of translucency. For example, compare translucentdisc-shaped pellets to translucent disc-shaped pellets, not withopaque, rectangular shaped pellets.4.3 Exact measurements of resin pellet color are not neces-sarily directly related to the color of the final cast, molded orextruded product d
21、ue to the multitude of variables, such asproducing variables, methods, and pellet shape and size. Colormeasurements can be useful for comparing resins in pellet formwhen all samples are similar in shape and size.4.4 A three-number tristimulus system is necessary to quan-tify color completely and pre
22、cisely. The general method used inthis procedure measures color using the CIE Systems describedin Practice E308, Test Method D2244, the CIE 1976 (X, Y, Z)system, and, the CIELAB 1976 color space.34.5 Individual components of the tristimulus measurementsuch as CIE Y (Luminance), Hunter L, a, b, or CI
23、E L*, a*, b*values or other useful metrics like yellowness index in accor-dance with Practice E313 can be used to describe colorattributes of materials.5. Interferences5.1 Comparisons of color measurements can only be madeif the material is the same, the pellet cut, size and shape areessentially the
24、 same and the test instrument is the same typeand within the same group. (See 6.2 and Section 10 and TablesA and B for instrument differences.)6. Apparatus6.1 Choices of apparatus include spectrophotometers, ortristimulus colorimeters, conforming to Guide E179.NOTE 4Most common white light sources u
25、sed in colorimetricinstruments are Tungsten Halogen, Pulsed Xenon, and LEDs.6.2 There are several different optical geometries currentlybeing used for measuring color. It is important that similaroptical geometries be used if results are to be compared. Theseare designated as Groups defined as follo
26、ws:6.2.1 Group ISpectrophotometer with 45 to 52-mm mini-mum port diameter with 0/45 directional geometry. See TestMethods E1347 and E1349.6.2.2 Group IIColorimeter with 31 to 52-mm minimumport diameter with 45/0 directional geometry. See Test Meth-ods E1347 and E1349.6.2.3 Group IIISphere with minim
27、um of 25-mm mini-mum port diameter with a nominal 0/diffuse geometry, mea-suring in the specular excluded mode. See Test Methods E1331and E1347.6.2.4 Group IVSphere with minimum of 25-mm mini-mum port diameter with a nominal diffuse/0 geometry, mea-suring in the specular excluded mode. See Test Meth
28、ods E1331and E1347.6.3 If other optical geometries are used for this test method,they need to be added to the standard.6.4 Calibrated tiles, for instrument standardization.6.5 Sample CupClear Glass, a minimum of 50-mm depth.NOTE 5The clear glass sample cup may be any shape that is largerthan the por
29、t.6.6 Black Sample Cover of sufficient size to prevent externallight from affecting the pellet measurement.7. Procedure7.1 Standardize the instrument in accordance with themanufacturers recommendations.7.2 Fill the sample cup to the top with pellets.7.3 Center the pellet filled sample cup at the sen
30、sor port formeasurement. Use a centering device if one is provided by themanufacturer.7.4 Cover the sample cup with an opaque, light exclusiondevice or cover.7.5 For Yellowness Index measurement of plastic pellets,make the necessary readings in CIE X, Y, Z tristimulus valuesand calculate Yellowness
31、Index in accordance with PracticeE313 using one of the following illuminant/observer combina-tions:7.5.1 CIE “Illuminant C” and 1931 2 Standard Observer.7.5.2 CIE “Illuminant D65” and 1964 10 Standard ObserverNOTE 6Care must be taken not to allow the pellet sample to remainat the measurement port fo
32、r a long period of time prior to measurement.Light exposure of high intensity may cause yellowness to change, thusaltering the test value.NOTE 7Many instruments will report the Yellowness Index inaccordance with Practice E313 directly thus no calculations are requiredfor individual Yellowness Index,
33、 YI, value.NOTE 8For other measurements, such as CIE X, Y, Z, Hunter L, a, b,or CIE L*, a*, b*, make the necessary instrument settings and take thereadings.7.6 Repeat steps 7.2 through 7.5.2 two more times for a totalof three results. Use dump-and-fill with fresh pellets for eachmeasurement.NOTE 9If
34、 there are not enough fresh pellets for three measurements,then it is recommended dumping the pellets and refilling the cup with thesame pellets for each measurement.8. Calculation8.1 Determine the average yellowness index, YI, ifrequested, using the following formula:YI 5 100 CxX 2 CzZ!/Y (1)3CIE P
35、ublication 015:2004 (Third Edition): Colorimetry. Currently availablethrough the U.S. National Committee of the CIE (cie-usnc.org) or the CIE website(http:/ Also, ANSI, New York, NY, USA, www.ansi.org.D6290 182where:YI = Yellowness Index,X, Y, Z =For C, CIE 1931 stnadard colorimetric observer (2):Cx
36、= 1.2769 andCz= 1.0592.OrFor D65, CIE 1964 standard colorimetric observer (10):Cx= 1.3013 andCz= 1.1498.9. Report9.1 Report the following information:9.1.1 Average of the Yellowness Index or other measure-ments if noted,9.1.2 Sample identification, such as lot number, source, etc.,9.1.3 Date test wa
37、s conducted,9.1.4 The instrument group port diameter, illuminant/observer combination, and9.1.5 The instrument used including name of manufacturer,model, and serial number.10. Precision and Bias410.1 Precision:10.1.1 Table 1 reflects data tested with ten instruments inGroup I, and Table 2with six in
38、struments in Group II. All dataare based on a round robin conducted in 1994-1995 inaccordance with Practice E691, involving eight materialstested with six test results measured on three days by eachlaboratory. For each material, pellets were gathered and pack-aged by one source and the individual pa
39、ckages were sent toeach of the laboratories which tested them. Each test result isthe value of an individual determination. Each laboratoryobtained six test results for each materials. Table 1A and Table2B reflect the values as if each test value consisted of anaverage of three readings. (WarningThe
40、 following explana-tions of r and R (10.1.2 through 10.1.4) only are intended topresent a meaningful way of considering approximate preci-sion of this test method. It is not appropriate to rigorouslyapply the data in Table 1, Table 2, Table 1A, and Table 2Atoacceptance or rejection of material, as t
41、hose data are specific tothe round robin and are not necessarily representative of otherlots, conditions, materials, or laboratories. Users of this testmethod need to apply the principles outlined in Practice E691to generate data specific to their laboratory and materials orbetween specific laborato
42、ries. The principles of 10.1.2 through10.1.4 then would be valid for such data.)10.1.2 Concept of r and RIf Srand SRhave been calcu-lated from a large enough body of data and for test results thatare the result of testing one specimen:10.1.3 Repeatability Limit, rThe value below which theabsolute di
43、fference between two individual test results obtainedunder repeatability conditions is likely to occur with a prob-ability of approximately 0.95 (95 %).4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D20-1235.TABLE 1 Yellowness
44、Index of PelletsApparatus Group IMaterial Average SrASRBrCRDMaterial G 3.99 0.206 0.495 0.576 1.385Material B 0.33 0.130 0.424 0.363 1.188Material F 0.133 0.113 0.524 0.317 1.467Material H 0.538 0.076 0.443 0.214 1.241Material C 1.539 0.095 0.398 0.267 1.116Material E 8.82 0.376 1.840 1.052 5.153Mat
45、erial A 15.8 0.365 0.877 1.023 2.455Material D 24.6 0.139 0.860 0.390 2.409TABLE 1A Yellowness Index of PelletsEstimate for Three Specimens (Apparatus Group I)Material Average SrASRBrCRDMaterial G 3.99 0.092 0.459 0.258 1.286Material B 0.33 0.058 0.408 0.162 1.143Material F 0.133 0.051 0.514 0.142 1
46、.439Material H 0.538 0.034 0.438 0.096 1.226Material C 1.539 0.043 0.389 0.119 1.090Material E 8.82 0.168 1.809 0.470 5.067Material A 15.8 0.163 0.813 0.458 2.278Material D 24.6 0.062 0.851 0.174 2.383ASris the within-laboratory standard deviation or the indicated material. It isobtained by pooling
47、the within-laboratory standard deviations of the test resultsfrom all of the participating laboratories:Sr5 ffss1d21ss2d22221ssnd2g/ng1/2BSRis the between-laboratories reproducibility, expressed as standard deviation:SR5 fSr21SL2g1/2where: SLis the standard deviation of laboratory means.Cr is the wi
48、thin-laboratory critical interval between two test results = 2.8 Sr.DR is the between-laboratories critical interval between two test results = 2.8 SR.TABLE 2 Yellowness Index of PelletsApparatus Group IIMaterial Average SrASRBrCRDMaterial G 5.32 0.361 1.01 1.01 2.82Material F 1.85 0.177 0.838 0.495
49、 2.35Material H 1.64 0.138 0.512 0.387 1.43Material B 1.61 0.152 0.646 0.425 1.81Material C 0.126 0.220 0.507 0.617 1.42Material E 7.21 0.289 2.20 0.810 6.15Material A 13.3 0.352 2.01 0.986 5.63Material D 20.6 0.167 1.45 0.468 4.07TABLE 2A Yellowness Index of PelletsEstimate for Three Specimens (Apparatus Group II)Material Average SrASRBrCRDMaterial G 5.32 0.161 0.908 0.452 2.54Material F 1.85 0.079 0.823 0.173 2.31Material H 1.64 0.062 0.497 0.173 1.39Material B 1.61 0.068 0.632 0.190 1.77Material C 0.126 0.09
