1、Designation: D 985 97 (Reapproved 2002)An American National StandardStandard Test Method forBrightness of Pulp, Paper, and Paperboard (DirectionalReflectance at 457 nm)1This standard is issued under the fixed designation D 985; the number immediately following the designation indicates the year ofor
2、iginal adoption or, in the case 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 determines the brightness of white,near-whi
3、te, and naturally colored pulp, paper, and paperboard.Brightness is a commonly used industry term for the numericalvalue of the reflectance factor of a sample, with respect to bluelight of specific spectral and geometric characteristics. This testmethod requires an instrument employing 45 illuminati
4、on and0 viewing geometry, with the illuminating and viewing beamsadjusted so that translucent materials are evaluated on anarbitrary but specific scale (1-4).21.2 This test method is applicable to all naturally-coloredpulps, and papers and board made from pulps. The measure-ment is not suitable for
5、paper and paperboard containing addedcoloring matter (such as yellow or green dyestuff) whichappreciably absorbs light in that part of the spectrum extendingfrom about 400 to 500 nm. Colored papers must be measuredspectrophotometrically or colorimetrically in order to obtainmeaningful results (TAPPI
6、 T442, T524, and T527). This testmethod is, however, suitable for pulps or papers which containoptical (fluorescent) brightening agents.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 es
7、tablish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 585 Practice for Sampling and Accepting a Single Lot ofPaper, Paperboard, Fiberboard, and Related Products3D 1968 Terminology Relating
8、to Paper and Paper Products32.2 TAPPI Standards:T 218 Forming handsheets for reflectance tests of pulp4T 442 Spectral reflectance factor, transmittance and color ofpaper and pulp (Polychromatic illumination)4T 452 Brightness of pulp, paper and paperboard (Direc-tional reflectance of 457 nm)4T 524 Co
9、lor of white and near-white paper and paperboardby L, a, b 45 0 colorimetry4T 527 Color of paper and paperboard in CIE system4T 1206 Precision statements for test methods43. Terminology3.1 DefinitionsDefinitions shall be in accordance withTerminology D 1968 and the Dictionary of Paper.44. Summary of
10、 Test Method4.1 This test method provides the following:4.1.1 A scale for measurement of paper brightness (bluedirectional reflectance factor),4.1.2 A method for verifying the calibration of each instru-ment used for brightness testing so that the user can rely uponthe test results, and4.1.3 Criteri
11、a for the geometric, and photometric character-istics required by instruments employed in the use of this testmethod.4.2 A procedure is also described for separating the fluores-cent component of brightness from the non-fluorescent com-ponent of brightness and measuring it quantitatively.5. Signific
12、ance and Use5.1 Brightness is the most extensively used optical propertyof pulp, paper, and paperboard. The measurement of brightness(blue reflectance) was originally devised as a means ofquantitatively assessing the effectiveness of pulp bleaching. Aspecific spectral response has been defined and r
13、igorouslymaintained, providing longterm stability of brightness valuesto the industry.5.2 The accurate determination of brightness is of vitalimportance in the buy-sell relationship between the paperproducer and consumer. High brightness is an indication of1This test method is under the jurisdiction
14、 of ASTM Committee D06 on Paperand Paper Products and is the direct responsibility of Subcommittee D06.92 on TestMethods.Current edition approved Dec. 10, 1997. Published October 1998. Originallyapproved in 1948. Last previous edition approved in 1993 as D 985 93.2The boldface numbers in parentheses
15、 refer to the list of references at the end ofthis test method.3Annual Book of ASTM Standards, Vol 15.09.4Available from the Technical Association of the Pulp and Paper Industry, P.O.Box 105113, Atlanta, GA 30348.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, P
16、A 19428-2959, United States.high-quality paper, resulting in a price structure where price isrelatively proportional to the brightness level. Paper producersare required to employ additional bleaching or the addition ofcostly optical brighteners in order to obtain high-brightnesspaper. The high cost
17、 of such brightening materials mandatesadherence to close production tolerances for the brightness ofthe end product.6. Apparatus6.1 Brightness TesterA test instrument which embodiesthe geometric and spectral characteristics specified in AnnexA1 and in such adjustment that its calibration is correct
18、 withinthe tolerances specified in Section 8.6.2 StandardsA set of five pads of paper sheets and twoopal glass standards as described in Section 8 and Annex A3.56.3 Backing Weight, 1-kg weight with flat bottom (used withtop loading instrument).7. Sampling and Test Specimens7.1 Sample Preparation:7.1
19、.1 Paper and Paperboard:7.1.1.1 Sample the material to be tested in accordance withPractice D 585. From each test unit, cut a representativeportion of the paper or board into seven or more sheets at least37 by 50 mm (112 by 2 in.) with the short dimension parallelto the machine direction. Avoiding a
20、ny watermark, dirt, orblemish, assemble the sheets in a pad with the top sides up.Using the top sheet as a cover only, mark it near one corner toidentify the sample and the top side. More than seven specimensheets may be required for thin or transparent samples toensure that the pad is completely op
21、aque. (Only a few sheetswill be required for paperboard.) The number of sheets in thepad should be such that the measured reflectance is notchanged by doubling the number of sheets.7.1.1.2 Do not touch test areas of the specimen with thefingers. Protect the test areas from contamination, excessivehe
22、at, or intense light.7.1.2 PulpPrepare sheets from pulp samples in accor-dance with TAPPI T 218.8. Calibration8.1 Obtain a set of paper and opal glass standards atmonthly intervals. Calibrate the test instrument in accordancewith manufacturers instructions, to the assigned values of amid-range paper
23、 tab and an opal glass standard.8.2 Check the test instrument readings against the assignedvalues of all five paper pads and two opal glass standards. If theinstrument reading on any individual paper pad or opal glassstandard differs from the respective assigned value by morethan 60.3 brightness poi
24、nts, adjust the instrument in accor-dance with the manufacturers instructions so that the readingsagree to within 0.3 brightness points.8.2.1 The brightness value for a paper pad is the average ofbrightness values obtained for the five sheets under the coversheet. The cover sheet is not to be measur
25、ed.8.3 Check the test instrument readings at least monthlyagainst the assigned values of five paper tabs and two opalglass standards. A check should be made with one of the opalglass standards at least daily. The frequency of these checkswill depend on the amount of use of the instrument and theaccu
26、racy required. Care should be exercised that the paperstandards do not become soiled through frequent use.8.4 At intervals of six months to two years, depending uponthe conditions and frequency of use, the test instrument shouldbe carefully inspected, tested, and adjusted to ensure that itsgeometric
27、 and spectral characteristics fall to within prescribedlimits, and that its photometric system is within the specifiedtolerances.9. Conditioning9.1 Preconditioning of test specimens for this test method isnot normally required.10. Procedure10.1 Measuring Brightness:10.1.1 Place the filter selector i
28、n the brightness position.10.1.2 Without touching the test areas with the fingers,remove the protective cover sheet and place it at the back of thepad. Place the pad over the specimen aperture of the instrumentwith the machine direction of the paper parallel to the planedetermined by the axis of the
29、 incident and reflected rays oflight and with the top side in contact with the instrument. If anorientation effect is suspected (as in testing of creped orembossed specimens), rotate the pad and observe the highestand lowest readings. Clearly record in the report how thespecimens are oriented and th
30、e reading for each orientation.10.1.3 Place the 1-kg backing weight on the pad or clampthe pad in place with the specimen clamp. Measure and recordthe brightness reading to at least 0.1 % reflectance.10.1.4 Move the sheet just measured to the back of the padand measure the second sheet while being b
31、acked by the pad.Repeat this procedure until five sheets have been measured.Average the five readings.10.2 Measuring Fluorescent Component of Brightness:10.2.1 Set the filter selector to the fluorescence position.10.2.2 Place the opal glass standard over the specimenaperture and, if necessary, adjus
32、t to the standard value.10.2.3 Place the specimen over the specimen aperture asdescribed in 10.1.2. Measure and record the brightness read-ings for five sheets and average the five readings as describedin 10.1.3 and 10.1.4.10.2.4 Calculate the fluorescent component by subtractingthe value obtained i
33、n 10.2.3 from the value obtained in 10.1.4.NOTE 1Some instruments automatically measure fluorescent compo-nent of brightness.11. Report11.1 Report the average brightness of the sample to onedecimal place together with the minimum and maximumreadings. State clearly and conspicuously any deviations fr
34、omthe standard procedure, and note any unusual features orcharacteristics of the sample.5Available from The Institute of Paper Science directional reflectance; fluorescence; fluo-rescent component; opal glass standards; optical brighteners;photometric; spectralANNEXES(Mandatory Information)A1. SPECT
35、RAL, GEOMETRIC, AND PHOTOMETRIC CHARACTERISTICS OF INSTRUMENTA1.1 Spectral CharacteristicsThe effective wavelengthof the instrument, when used with the filter required for thistest method is 457.0 6 0.5 nm. The effective wavelength is thatwavelength of monochromatic light for which the transmit-tanc
36、e of a filter having a spectral transmittance given by theequation t=a+bl is equal to that determined with a masterinstrument, after a correction is made for effects associatedwith refraction and reflection, angular spread of rays throughthe filter, photometric error, and the wavelength error in the
37、spectrophotometer employed to determine the spectral trans-mittance. In this equation, which need hold only for thatwavelength range transmitted by the brightness filter, T istransmittance, a and b are constants, and l is the wavelength.Filters having positive and negative b values should beemployed
38、 so that, by averaging the two effective wavelengthdeterminations, the correct effective wavelength will be ob-tained even though a photometric error may be present.Differences between the two values can be related to thephotometric error, which in the master instrument is not greaterthan 0.1 %. A s
39、uitable correction should be applied if aphotometric error exists. The spectral transmittance of thelinear filter is measured relative to a clear, nonabsorbing plateof equal thickness and similar index of refraction. The spectraltransmittance is so measured in both the master instrumentsand the spec
40、trophotometer, the filters are so disposed withrespect to apertures as to minimize error due to scattering oflight in the filters and to make such error as may be due to lightscattering the same in the master instrument and the spectro-photometer.A1.1.1 The spectral power distribution of the light i
41、ncidenton the specimen determines the response of the instrument tofluorescent radiation which may be caused by presence offluorescent whitening agents. The product of the spectralpower distribution of the source and the spectral transmittanceof the glass lenses and filter in the incident system is
42、E(l),where E(l) is the function of wavelength given in Table A1.1.A1.1.2 The effective wavelength, 457.0 6 0.5 nm is ob-tained by the combination of illuminant, glass optics, filters,and photodetector for which the mathematical product ofrelative spectral power distribution, spectral transmittance,
43、andspectral response is F(l), where F(l), is the function ofwavelength given in Table A1.2. The area under the curvewhich represents the product for all wavelengths greater than700 nm of the spectral sensitivity of the photoelectric cell, andthe spectral transmittance of all filters between the spec
44、imenaperture and the photoelectric cell, is so small compared witha similar area for the wavelength range from 395 to 515 nmthat no detectable part of the photoelectric current may beascribed to infrared fluorescence of the test specimen.A1.2 Geometric CharacteristicsThe mean angle of inci-dence of
45、light rays upon the test specimen is 45 6 0.5.A1.2.1 The incident rays upon a point of the test specimenare confined within a cone having a half angle of 11.5 6 2.6Conducted by Collaborative Testing Services, Inc.TABLE A1.1 Relative Spectral Energy Distribution of LightIncident on SpecimenNOTE 1Colo
46、r temperature of the light source is 2800 6 100 K.Wavelength, nm E(l), relative units320 0.0330 0.7340 3.0360 9.7380 17.1400 26.0420 37.2440 50.3460 64.1480 80.0500 100.0D 985 97 (2002)3This cone is filled with light, the vertex is in the specimenaperture, and the base is at the emergent aperture of
47、 thecondensing lenses.A1.2.2 The specimen aperture is circular with a diameter of12.7 6 0.13 mm (0.500 6 0.005 in.). The exit aperture of theoptical system which accepts reflected rays for measurement isconcentric and parallel to the specimen aperture and has adiameter of 9.53 6 0.076 mm (0.375 6 0.
48、003 in.) so that lightreflected from the rim of the specimen aperture does not reachthe photocell.A1.2.3 The mean angle of rays, reflected by the test speci-men and accepted by the receiving optical system for measure-ment, is between 0 and 0.5 with the normal to the plane of thespecimen aperture.A1
49、.2.4 The reflected rays accepted for measurement areconfined to a cone having a half angle of 22.5 6 2.A1.3 Photometric CharacteristicsThe instrument incor-porates a photometric measurement system which measuresreflectance in direct proportion to the light energy incidentupon the sample within 0.1 % throughout the entire range ofmeasurement. Suitable checks must be made to ensure thelong-term stability of the spectral, geometric, and photometriccharacteristics of the master instrument.A2. CALIBRATION SERVICEA2.1 The brightness scale is based on the reflectance ofma
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1