1、Designation: D6290 051Standard 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
2、parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEAdded research report information to Section 10 editorially in September 2010.1. Scope*1.1 This test method is intended primarily for the instru-mental
3、measurement of the degree of yellowness (or change ofdegree of yellowness) under daylight illumination of homoge-neous, nonfluorescent, nearly-colorless transparent or nearly-white translucent or opaque plastics. The measurement is madeon pellets and based on tristimulus values obtained with aspectr
4、ophotometer or colorimeter.1.2 This test method is applicable to the color analysis ofplastic pellets. Each material may have unique characteristicsthat determine the color values.1.3 This procedure outlines a method to determine colormeasurements, such as Yellowness Index, CIE X, Y, Z, andHunter L,
5、 a, b, or CIE L*, a*, b*.1.4 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 and health practices and determine the applica-bility of regulatory limitations pri
6、or to use.NOTE 1There is no equivalent ISO Standard.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesE179 Guide for Selection of Geometric Conditions fo
7、rMeasurement of Reflection and Transmission Properties ofMaterialsE284 Terminology of AppearanceE308 Practice for Computing the Colors of Objects byUsing the CIE SystemE313 Practice for Calculating Yellowness and WhitenessIndices from Instrumentally Measured Color CoordinatesE691 Practice for Conduc
8、ting an Interlaboratory Study toDetermine the Precision of a Test MethodE1331 Test Method for Reflectance Factor and Color bySpectrophotometry Using Hemispherical GeometryE1347 Test Method for Color and Color-Difference Mea-surement by Tristimulus ColorimetryE1349 Test Method for Reflectance Factor
9、and Color bySpectrophotometry Using Bidirectional (45:0 or 0:45)Geometry3. Terminology3.1 Definitions Refer to Terminologies D883 and E284for definitions of terms used in this test method.4. Significance and Use4.1 Before proceeding with this test method, referenceshould be made to the specification
10、 of the material being tested.Any test specimen preparation, conditioning, dimensions, ortesting parameters, or a combination thereof, covered in thematerials specification shall take precedence over those men-tioned in this test method. If there are no material specifica-tions, then default conditi
11、ons apply.NOTE 2Some materials, such as polyamide (nylon), can be cooledvery differently during the production of the pellets. This variation in thecooling of the pellets can result in different levels of crystallinity in thepellets only. More crystalline nylons will be more opaque than amorphousnyl
12、ons. This will 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 materialspeci
13、fications.4.2 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, siz
14、e, texture, and1This 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 April 1, 2005. Published June 2005. Originallyapproved in 1998. Last previous edition approved in 1998 as
15、 D6290 - 981. DOI:10.1520/D6290-05E01.2For 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.1*A Summary of Changes
16、section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.degree of translucency. For example, translucent disc-shapedpellets should be compared to translucent disc-shaped pellets,not with opaque, rec
17、tangular shaped pellets.4.3 Exact measurements of resin pellet color may not bedirectly related to the color of the final cast, molded orextruded product due to the multitude of variables, such asproducing variables, methods, and pellet shape and size. Colormeasurements can be useful for comparing r
18、esins 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 precisely. The general method used inthis procedure measures color using the CIE Systems describedin Practice E308, Test Method D2244, the CIE 1976
19、(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 CIE L*, a*, b*values or other useful metrics like yellowness index can beused to describe color attributes of materials. This test methoddescribes
20、a standard procedure on how these measurements aremade.5. Interferences5.1 Comparisons of color measurements can only be madeif the material is the same, the pellet cut, size and shape areessentially the same and the test instrument is the same typeand within the same group. (See 6.2 and Section 10
21、and TablesA and B for instrument differences.)6. Apparatus6.1 Apparatus may be spectrophotometer, or tristimuluscolorimeter, conforming to Guide E179.6.2 There are several different optical geometries currentlybeing used for measuring color. It is important that similaroptical geometries be used if
22、results are to be compared. Theseare designated as Groups defined as follows:6.2.1 Group ISpectrophotometer with 45 to 52-mm portwith 0/45 directional geometry. See Test Methods E1347 andE1349.6.2.2 Group IIColorimeter with 52-mm port with 45/0directional geometry. See Test Methods E1347 and E1349.6
23、.2.3 Group IIISphere with minimum of 25-mm port witha nominal 0/diffuse geometry. See Test Methods E1331 andE1347.6.2.4 Group IVSphere with minimum of 25-mm port witha nominal diffuse/0 geometry. See Test Methods E1331 andE1347.6.3 There may be other optical geometries being used forthis test method
24、, which should be added if being used andbrought to our attention as this procedure is being evaluated.6.4 Calibrated tiles, for instrument standardization.6.5 Glass (clear), specimen cell at least 60-mm 212-in.diameter and a minimum of 50-mm depth and black samplecover of sufficient size to prevent
25、 external light from affectingthe pellet measurement.NOTE 4The clear sample holder may be any shape that is larger thanthe port with at least 6-mm between the edge of the port and the edge ofthe sample holder.7. Procedure7.1 Standardize the instrument in accordance with themanufacturers written inst
26、ructions (usually once per shift).7.2 Fill the sample cup to the top with pellets.7.3 Center the pellet filled cup at the sensor 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 Yellownes
27、s Index make, the necessary readings ofTristimulus X,Y, Z to determineYellowness Index as describedin Test Method E313 as soon as possible using illuminant “C”,specular excluded, and CIE 1931 2 observer.NOTE 5Care must be taken not to allow the pellet sample to remainat the measurement port for a lo
28、ng period of time prior to measurement.Light exposure of high intensity may cause yellowness to change, thusaltering the test value.NOTE 6Many instruments will report the Yellowness Index in accor-dance with Test Method E313 directly thus no calculations are required forindividual Yellowness Index v
29、alue.7.5.1 For other measurements, such as Hunter L, a, b or CIEL*, a*, b* make the necessary instrument settings and take thereadings.7.6 Repeat steps 7.2 through 7.5.1 two more times for a totalof three results.8. Calculation8.1 Determine the average yellowness index, YI, if re-quested, using the
30、following formula:YI 5 100 CxX CzZ!/Y (1)where:Cx= 1.2769, andCz= 1.0592.8.2 Determine the average yellowness index by summingthe test values and divide by the number of samples tested.9. Report9.1 Report the following information:9.1.1 Average of the Yellowness Index or other measure-ments if noted
31、,9.1.2 Sample identification, such as lot number, source, etc.,9.1.3 Date test was conducted,9.1.4 The instrument group or geometry, 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
32、 instruments inGroup I, and Table 2 with six instruments in Group II. All dataare based on a round robin conducted in 1994-1995 in3Based upon the Colorimetry, 2nded., Publication CIE No. 15.2, Central Bureauof the CIE, Vienna, 1986. Currently available through the U.S. National Committeeof the CIE,
33、% Mr. Thomas Lemmons, TLA Lighting Consultants, Inc., 7 Pond St.,Salem, MA 019704819.4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D20-1235.D6290 0512accordance with Practice E691, involving eight materialstested with six test
34、 results measured on three days by eachlaboratory. For each material, pellets were gathered and pack-aged by one source and the individual packages were sent toeach of the laboratories which tested them. Each test result isthe value of an individual determination. Each laboratoryobtained six test re
35、sults for each materials. Table 1A and Table2B reflect the values as if each test value consisted of anaverage of three readings. (WarningThe 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 met
36、hod. The data in Table 1, Table 2, Table 1A,and Table 2A should not be applied rigorously to acceptance orrejection of material, as those data are specific to the roundrobin and may not be representative of other lots, conditions,materials, or laboratories. Users of this test method shouldapply the
37、principles outlined in Practice E691 to generate dataspecific to their laboratory and materials or between specificlaboratories. The principles of 10.1.2 through 10.1.4 thenwould 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 fo
38、r test results thatare the result of testing one specimen:10.1.3 Repeatability Limit, r (Comparing two test results forthe same material, obtained by the same operator using thesame equipment on the same day)The two test results shouldbe judged not equivalent if they differ by more than the r valuef
39、or that material.TABLE 1 Yellowness 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 1.116Materi
40、al E 8.82 0.376 1.840 1.052 5.153Material 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 1.143
41、Material F 0.133 0.051 0.514 0.142 1.439Material 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
42、 material. It isobtained by pooling the within-laboratory standard deviations of the test resultsfrom all of the participating laboratories:Sr5 s1!21 s2!22221sn!2#/n1/2BSRis the between-laboratories reproducibility, expressed as standard devia-tion:SR5 Sr21 SL2#1/2where: SLis the standard deviation
43、of laboratory means.Cr is the within-laboratory critical interval between two test results = 2.8 3 Sr.DR is the between-laboratories critical interval between two test results = 2.8 3SR.TABLE 2 Yellowness Index of PelletsApparatus Group IIMaterial Average SrASRBrCRDMaterial G 5.32 0.361 1.01 1.01 2.
44、82Material F 1.85 0.177 0.838 0.495 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 Pelle
45、tsEstimate 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 0.098 0.467 0.276 1.31Material E 7.21 0.129 2.18 0.36
46、2 6.11Material A 13.3 0.158 1.98 0.441 5.56Material D 20.6 0.075 1.44 0.209 4.05ASris the within-laboratory standard deviation or the indicated material. It isobtained by pooling the within-laboratory standard deviations of the test resultsfrom all of the participating laboratories:Sr5 s1!21 s2!2222
47、1sn!2#/n1/2BSRis the between-laboratories reproducibility, expressed as standard devia-tion:SR5 Sr21 SL2#1/2where: SLis the standard deviation of laboratory means.Cr is the within-laboratory critical interval between two test results = 2.8 3 Sr.DR is the between-laboratories critical interval betwee
48、n two test results = 2.8 3SR.TABLE 3 Yellowness Index of PelletsAll Apparatus GroupsMaterial Average SrASRBrCRDMaterial G 4.69 1.04 1.45 2.92 4.05Material F 1.61 1.06 1.91 2.96 5.36Material B 0.979 0.504 1.03 1.41 2.88Material H 0.014 4.13 4.13 11.6 11.6Material C 2.08 5.77 5.77 16.2 16.2Material E
49、6.51 2.45 3.77 6.87 10.6Material A 12.7 3.78 4.87 10.6 13.6Material D 20.7 3.94 5.50 11.0 15.4TABLE 3A Yellowness Index of PelletsEstimate for Three SpecimensAll Apparatus GroupsMaterial Average SrASRBrCRDMaterial G 4.69 0.466 1.11 1.30 3.10Material F 1.61 0.473 1.66 1.33 4.66Material B 0.979 0.226 0.925 0.632 2.59Material H 0.014 1.85 1.85 5.17 5.17Material C 2.08 2.58 2.58 7.23 7.23Material E 6.51 1.10 3.07 3.07 8.60Material A 12.7 1.69 3.50 4.73 9.81Material D 20.7 1.76 4.23 4.93 4.23ASris the within-laboratory st
