1、Designation: D4660 12Standard Test Methods forPolyurethane Raw Materials: Determination of the IsomerContent of Toluenediisocyanate1This standard is issued under the fixed designation D4660; the number immediately following the designation indicates the year oforiginal adoption or, in the case of re
2、vision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These test methods measure the amount of toluene-2,6-diisocyanate (2,6-TDI) isomer or toluene2,4d
3、iisocyanate(2,4-TDI) isomer in mixtures of the 2,4- and 2,6-isomers oftoluenediisocyanate (TDI). Two different test methods areprovided to give accurate results over the broad range ofisomer concentrations possible.1.1.1 Test Method AApplicable to TDI samples contain-ing 5 to 95 % of 2,6-TDI isomer
4、(5 to 95 % 2,4-TDI isomer).1.1.2 Test Method BApplicable to TDI samples contain-ing 0 to 5 % of 2,6-TDI isomer (95 to 100 % 2,4-TDI isomer).NOTE 1These test methods are equivalent to ISO 15064.1.2 The values stated in SI units are to be regarded asstandard.1.3 This standard does not purport to addre
5、ss 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 prior to use.2. Referenced Documents2.1 ASTM Standards:2D883 Terminolog
6、y Relating to PlasticsE180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals32.2 ISO Standard:4ISO 15064 PlasticsAromatic Isocyanates for Use in theProduction of PolyurethanesDetermination of the Iso-mer Ratio in Toluenediisocyanate
7、3. Terminology3.1 Terminology in these test methods is in accordance withTerminology D883.3.2 Definitions of Terms Specific to This Standard:3.2.1 isomera compound having the same molecular for-mula (percentage composition and molecular weight) as an-other compound but differs in chemical or physica
8、l properties.3.2.2 isomer contentthe amount of an isomer expressed asa percentage of total 2,4 and 2,6-TDI isomer amount.4. Summary of Test Methods4.1 Both test methods are based on the quantitative mea-surement of absorption bands arising from out-of-plane C-Hdeformation vibrations of the aromatic
9、ring.4.2 In Test Method A, the infrared spectrum of a cyclo-hexane solution of the sample is recorded in the 770 to840-cm1region. The absorbance ratio of the 805 cm1to the782 cm1band is measured and converted to percent 2,6-TDI,or percent 2,4-TDI, or both, from a previously establishedcalibration cu
10、rve.4.3 In Test Method B, the absorbance of the 782-cm1bandis measured from an infrared spectrum of an undiluted sampleand then converted to percent 2,6-TDI from a previouslyestablished calibration curve.5. Significance and Use5.1 These test methods can be used for research or forquality control to
11、determine the isomer content of toluenediisocyanates.5.2 The isomer content of a toluene diisocyanate relates toits reactivity.6. Apparatus6.1 SpectrophotometerAny single- or double-beam re-cording infrared spectrophotometer accurate to 0.2 % transmis-sion and capable of resolving the two peaks of t
12、he 2,4-TDIisomer doublet at 805-815 cm1(see Fig. 1).1These test methods are under the jurisdiction of ASTM Committee D20 onPlastics and are the direct responsibility of Subcommittee D20.22 on CellularMaterials - Plastics and Elastomers.Current edition approved May 1, 2012. Published June 2012. Origi
13、nallyapproved in 1959. Last previous edition approved in 2006 as D4660 - 06. DOI:10.1520/D4660-12.2For 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 Docu
14、ment Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1*A Summary of Changes section appears at
15、 the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2 Cells, sealed sodium chloride (NaCl) liquid absorptioncells with 0.2-mm (Test Method A) and 0.1-mm (Test MethodB) path lengths. The actual thicknesses of th
16、e cells are to beknown to 60.002 mm.6.3 Glassware, 25-mL, glass-stoppered, volumetric flasks,10-mL, glass-stoppered, flasks, 0.80-mL volumetric pipet, andan all-glass syringe.7. Reagents and Materials7.1 Purity of ReagentsUse reagent grade chemicals in alltests. Unless otherwise noted, all reagents
17、conform to thespecifications of the Committee on Analytical Reagents of theAmerican Chemical Society where such specifications areavailable.5Other grades may be used, provided it is ascertainedthat the reagent is of sufficiently high purity to permit its usewithout lessening the accuracy of the dete
18、rmination.7.2 Cyclohexane, anhydrous, stored over molecular sieve.7.3 Diisocyanate StandardsPure samples of 2,4-TDI and2,6-TDI are required for calibration. The following criteria canbe used to judge purity:Pure Isomer Freezing point Refractive Index 20C n20DDensity 20C/4C2,4-TDI 22.0C 1.56781 1.218
19、62,6-TDI 18.2C 1.57111 1.22708. Sampling8.1 Since organic isocyanates react with atmospheric mois-ture, take special precautions in sampling. Usual samplingmethods, even when conducted rapidly, can cause contamina-tion of the sample with insoluble urea. Therefore, blanket thesample with dry air or n
20、itrogen at all times. (WarningManydiisocyanates are known or suspected sensitizers. Over-exposure to diisocyanates can lead to adverse health effectswhich include the development of occupational asthma andother respiratory, skin and eye effects. Engineering controlsand/or personal protective equipme
21、nt, including respiratory,skin and eye protection, are to be used when there is a potentialfor over-exposure to diisocyanates. The product suppliersMaterial Safety Data Sheet (MSDS) provides more detailedinformation about potential adverse health effects and otherimportant safety and handling inform
22、ation. Always follow thespecific instructions provided on the MSDS.)9. Test Conditions9.1 Since isocyanates react with moisture, keep laboratoryhumidity low, preferably around 50 % relative humidity.TEST METHOD ASAMPLES CONTAINING 5 TO95 % 2,6-TDI10. Calibration10.1 Weigh amounts of pure 2,4-TDI and
23、 2,6-TDI into dry,10-mL, glass-stoppered flasks (Note 2) to obtain the weightratios given in 10.1.1 or 10.1.2. Carefully shake the mixtures.From the weights of pure 2,4-TDI and 2,6-TDI, calculate theweight ratios (2,4-TDI to 2,6-TDI), or the weight percentcomposition of the mixtures, or both, expres
24、sed to foursignificant figures.NOTE 2Carefully dry all glassware since the diisocyanates reactreadily with moisture.10.1.1 Approximate standard mixtures for wide-range cali-bration are given in Table 1 (5-95 % 2,6-TDI).10.1.2 Approximate standard mixtures for narrow-rangecalibrations (see Note 3) ar
25、e given in Table 2 (15-25 %2,6-TDI) and Table 3 (30-40 % 2,6-TDI).NOTE 3Calibration over a narrow range covering the expected isomerratio gives more accurate results than a wide-range calibration.10.2 Preparation of Standard Solutions Using a pipet,transfer 0.80 mL(0.98 g) of standard mixture into a
26、 dry, 25-mLglass-stoppered, volumetric flask. Dilute to volume with cy-clohexane and mix thoroughly.10.3 Fill two 0.2-mm sealed, liquid absorption cells (one fora single-beam instrument) with cyclohexane and record itsspectrum from 770 to 840 cm1. Refill the sample cell with astandard solution from
27、10.2 and record the spectrum superim-posing it over the previously recorded solvent spectrum. The5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar S
28、tandards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.FIG. 1 IR Scan of TDI Showing 2,4-TDI Isomer Doublet at 810 cm1and 2,6 TDI Isomer at 782 cm1D4660 122instrument controls
29、 must remain unchanged between the blankand the standards of a given series. Repeat the process for eachstandard solution from 10.2.10.4 Using the solvent spectrum as the baseline, measurethe absorbance of each standard solution sample at 805cm1(2,4-TDI) and 782 cm1(2,6-TDI) and calculate the 805/78
30、2-cm1absorbance ratio. Construct a calibration curve (seeFig. 2) by plotting absorbance ratio (ordinate) versus weightratio of 2,4-TDI to 2,6-TDI (abscissa).10.5 For convenience in short-range calibrations, the absor-bance ratio may be plotted against the concentration, expressedin weight percent, o
31、f each isomer (see Figs. 3 and 2). Thisallows direct determination of composition without equations,however, the relationship is not linear and the shape of thecalibration curve must be carefully determined.11. Procedure11.1 Using a dry pipet, transfer 0.8 mL (0.98 g) of sampleinto a dry, 25-mL, gla
32、ss-stoppered, volumetric flask. Dilute tovolume with anhydrous cyclohexane and mix thoroughly. Fillthe 0.2-mm cell with the cyclohexane and record the blanksolvent spectrum from 770 to 840 cm1. Without changinginstrument settings, refill the sample cell with the samplesolution and record its spectru
33、m superimposed on the blanksolvent spectrum.12. Calculation12.1 Using the solvent spectrum as the baseline, measurethe absorbance of the sample at 805 cm1(2,4-TDI) and 782cm1(2,6-TDI) and calculate the 805/782-cm1absorbanceratio. From the appropriate standard curve, obtain the percent-age compositio
34、n (Figs. 3 and 2), or isomer weight ratio (R),(Fig. 4), or both, that corresponds to the measured absorbanceratio.12.2 When using the isomer weight ratio, ( R), calculate thepercentage of each isomer as follows:Percent 2,62TDI 5100R 1 1!(1)andPercent 2,42TDI 5 100 2 percent 2,62TDI (2)12.3 Express t
35、he result to one decimal place.13. Precision and Bias13.1 PrecisionTable 4 is based on a round robin con-ducted in 1994 involving two samples tested by eight labora-tories. For each material, all the samples were prepared at onesource, but the individual specimens were prepared at thelaboratories th
36、at tested them. Each laboratory obtained ten testresults for each material on a given day. Narrow-range cali-brations were used.13.1.1 The following explanations of r and R (13.1.2-13.1.4) are only intended to present a meaningful way ofconsidering the approximate precision of this test method. Thed
37、ata in Table 4 are not to be rigorously applied to theacceptance or rejection of material, as these data apply only tothe materials tested in the round robin and are unlikely to berigorously representative of other lots, conditions, materialsand laboratories. Users of this test method should apply t
38、heprinciples outlined in Practice E180 to generate data specific totheir laboratory and materials, or between specific laboratories.The principles of 13.1.2-13.1.4 would then be valid for suchdata.13.1.2 Repeatability, rTwo results obtained within onelaboratory shall be judged not equivalent if they
39、 differ by morethan the r value for that material where r is the intervalrepresenting the critical difference between two test results forthe same material, obtained by the same operator using thesame equipment on the same day in the same laboratory.13.1.3 Reproducibility, RTwo test results obtained
40、 bydifferent laboratories shall be judged not equivalent if theydiffer by more than the R value for that material where R is theinterval representing the critical difference between two testresults for the same material, obtained by different operatorsusing different equipment in different laborator
41、ies.13.1.4 Any judgment in accordance with 13.1.2 and 13.1.3would have an approximate 95 % (0.95) probability of beingcorrect.TABLE 1 Approximate Standard Mixtures for Wide-RangeCalibration, 595 % 2,6-TDIWeight Ratio%, 2,4-TDI %, 2,6-TDI 2,4-/2,6-TDI5.0 95.0 0.0510.0 90.0 0.1120.0 80.0 0.2530.0 70.0
42、 0.4340.0 60.0 0.6750.0 50.0 1.0060.0 40.0 1.5070.0 30.0 2.3380.0 20.0 4.0090.0 10.0 9.0095.0 5.0 19.00TABLE 2 Approximate Standard Mixtures for Narrow-RangeCalibration, 1525 % 2,6-TDIWeight Ratio%, 2,4-TDI %, 2,6-TDI 2,4-/2,6-TDI75.0 25.0 3.0078.5 21.5 3.6579.0 21.0 3.7679.5 20.5 3.8880.0 20.0 4.00
43、80.5 19.5 4.1381.0 19.0 4.2681.5 18.5 4.4085.0 15.0 5.67TABLE 3 Approximate Standard Mixtures for Narrow-RangeCalibration, 3040 % 2,6-TDIWeight Ratio%, 2,4-TDI %, 2,6-TDI 2,4-/2,6-TDI60.0 40.0 1.5063.5 36.5 1.7464.0 36.0 1.7764.5 35.5 1.8265.0 35.0 1.8665.5 34.5 1.9066.0 34.0 1.9466.5 33.5 1.9870.0
44、30.0 2.33D4660 12313.2 BiasThere are no recognized standards by which toestimate the bias of this test method.FIG. 2 Calibration Curve Toluene Diisocyanate 65:35 (2,4-TDI : 2,6-TDI)FIG. 3 Calibration Curve Toluene Diisocyanate 80:20 (2,4-TDI : 2,6-TDI)D4660 12413.3 It has also been estimated that th
45、e results reported bylaboratories are to be considered suspect if they differ from oneanother by more than 60.34 % isomer (narrow-range calibra-tion).TEST METHOD BSAMPLES CONTAINING0 TO 5 % 2,6-TDI14. Calibration14.1 Using pure 2,4- and 2,6-TDI and dry, 10-mL, glass-stoppered flasks, prepare a serie
46、s of calibration mixtures asgiven in Table 5.14.2 From the weights of pure 2,4- and 2,6-TDI, calculatethe concentration of 2,6-TDI in each of the mixtures, expressedto four significant figures.14.3 Using a 0.1-mm sealed liquid absorption cell, recordthe spectrum of each of the calibration mixtures f
47、rom 770 to840 cm1.14.4 For each of the calibration mixtures, measure theabsorbance of the 2,6-TDI isomer band at 782 cm1from abaseline-drawn tangent to the band shoulders.14.5 Construct a calibration curve by plotting the absor-bance (ordinate) versus the concentration of 2,6-TDI (abscissa)expressed
48、 in weight percent, (see Fig. 4). This allows directdetermination of composition without equations.15. Procedure15.1 Fill the 0.1-mm cell with the sample and record thespectrum from 770 to 840 cm1.16. Measurement16.1 Measure the absorbance of the 2,6-TDI isomer band at782 cm1and obtain the percentag
49、e of 2,6-TDI from thecalibration curve.17. Precision and Bias17.1 Attempts to develop a full precision and bias statementfor this test method have not been successful. For this reason,data on precision and bias cannot be given. Because this testmethod does not contain a round-robin-based numerical preci-sion and bias statement, it shall not be used as a referee testmethod in case of dispute.Anyone wishing to participate in thedevelopment of precision and bias data should contact theChairman, Subcommittee D20.00 (Section 20.00.00),
