1、Designation: D6099 08D6099 13Standard Test Method forPolyurethane Raw Materials: Determination of Acidity inModerate to High Acidity Aromatic Isocyanates1This standard is issued under the fixed designation D6099; the number immediately following the designation indicates the year oforiginal adoption
2、 or, in the case of revision, 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 This test method determines the acidity, expressed as parts per million (pp
3、m) of HCl, in aromatic isocyanate samples ofgreater than 100ppm acidity. The test method is applicable to products derived from toluene diisocyanate and methylene-bis-(4phenylisocyanate) (see Note 1).NOTE 1This test method is equivalent to ISO 14898, Test Method A.2. Referenced Documents2.1 ASTM Sta
4、ndards:2D883 Terminology Relating to PlasticsE180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals(Withdrawn 2009)3E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method2.2 ISO Standards:I
5、SO 14898 PlasticsAromatic isocyanates for use in the production of polyurethaneDetermination of acidity43. Terminology3.1 DefinitionsTerms used in this test method are in accordance with Terminology D883.3.2 Definitions of Terms Specific to This Standard:3.2.1 acidity, nthe acid strength of a sample
6、 expressed in ppm hydrochloric acid.HCl.4. Summary of Test Method4.1 The isocyanate is mixed with an excess of methanol and a cosolvent. Additional acid is released into the solvent systemduring urethane formation. The acid then is titrated potentiometrically with methanolic KOH, and the acidity pre
7、sent in theisocyanate sample is calculated from the titer.5. Significance and Use5.1 This test method can be used for research or for quality control to characterize aromatic isocyanates and prepolymers ofmoderate to high acidity. Acidity correlates with performance in some polyurethane systems.6. A
8、pparatus6.1 250-mL Beakers.6.2 50-mL Pipet or Repipet, Class A volumetric.6.3 100-mL Pipet or Repipet, Class A volumetric.1 This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.22 on Cellular Materials - Plasticsand Elastom
9、ers.Current edition approved Nov. 15, 2008Sept. 1, 2013. Published November 2008September 2013. Originally approved in 1997. Last previous edition approved in20032008 as D6099 - 03.D6099 - 08. DOI: 10.1520/D6099-08.10.1520/D6099-13.2 For referencedASTM standards, visit theASTM website, www.astm.org,
10、 or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.4 Available from American National Standard
11、s Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to
12、adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright A
13、STM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.4 Automatic Titration Equipment, capable of inflection detection and stirring the sample while, titrating, such as:6.4.1 Commerically-available Automatic Titration Apparatus,6.4.2 Reference Elect
14、rode, with saturated LiCl/ethanol solution in both chambers.6.4.3 pH Glass Electrode, (see Note 2).NOTE 2A combination pH electrode with internal reference also may be used.6.5 Magnetic Stirrer.6.6 Stir Bars.6.7 Watch Glasses.6.8 Analytical Balance, capable of weighing to the nearest 1 mg.7. Reagent
15、s and Materials7.1 0.02 N KOH in Methanol1.32 g KOH pellets (85 % KOH)/1000 mL methanol, standardized with potassium hydrogenphthalate (KHP).7.2 Toluene or 1,2,4Trichlorobenzene (TCB), dried for 24 h over molecular sieves.7.3 Anhydrous Methanol.8. Sampling8.1 Since organic isocyanates react with atm
16、ospheric moisture, take special precautions in sampling. Usual sampling methods,even when conducted rapidly, can cause contamination of the sample with insoluble urea. Therefore, blanket the sample with dryair or nitrogen at all times.NOTE 3Warning:Many diisocyanates are known or suspected sensitize
17、rs. Over-exposure to diisocyanates can lead to adverse health effects which mayinclude the development of occupational asthma and other respiratory, skin and eye effects. Engineering controls and/or personal protective equipment,including respiratory, skin and eye protection, should are to be used w
18、hen there is a potential for over-exposure to diisocyanates. The product suppliersMaterial Data Safety Sheet (MSDS) provides more detailed information about potential adverse health effects and other important safety and handlinginformation. Always follow the specific instructions provided on the MS
19、DS.9. Calibration9.1 Calibrate the electrodes using pH 4 and pH 7 aqueous buffers.10. Test Conditions10.1 Since isocyanates react with moisture, keep laboratory humidity low, preferably around 50 % relative humidity.11. Procedure11.1 All samples shall be done in duplicate.11.2 Accurately weigh to th
20、e nearest 1 mg, 10 g of sample into a 250-mL beaker.11.3 Add 50 mL of dried toluene or TCB.NOTE 4If this test method is used for prepolymers, substitute THF as the solvent. THF has been used as a solvent for prepolymers.11.4 Add 100 mL of methanol into the solution.11.5 Add a stir bar, cover with a
21、watch glass, and stir for 20 min.NOTE 5Samples must be at room temperature before titration. Warm samples cause more frequent electrode clogging.11.6 With uniform stitrring of the sample, automatically titrate the mixture with 0.02 N methanolic KOH through thepotentiometrically-determined inflection
22、 end point between apparent pH 4 and 9. Follow manufacturers instructions forinstrument-specific parameters for set-up, calibration and analysis of samples.NOTE 6If results indicate a drift in the data or a slow electrode response, the pH electrode should be cleaned by soaking in 2:1 sulfuric: nitri
23、c acidsfor 10 min, followed by soaking in water for 20 min, and then rinsing with acetone.11.7 Record the titrant volume for the potentiometric end point. If more than one potentiometric end point is found, record theone at highest apparent pH less than 7.NOTE 7The inflection point typically is at a
24、pparent pH between 4 and 5.11.7.1 If no clear end point can be identified, calculate results using the end point at apparent pH 7.0, and report the result asacidity at apparent pH 7.0.D6099 13212. Calculation12.1 Calculate the acidity as ppm HCl as follows:Acidity ppm HCl!5 Vsam! 3N 3Fsample weightg
25、!# (1)where:Vsam = volume of titrant needed for the sample, mL,N = normality of the titrant solution, andF = 36465= 36.465 (mol weight of HCl) 1000 (factor to change mg/g to g/g, that is, ppm).F = 36 465 (mol weight of HCl) 1000 (factor to change mg/g to g/g, that is, ppm).13. Report13.1 The result
26、is reported as the average of duplicates, expressed as ppm HCl, to the nearest 1 ppm. Any unusual conditionsduring the operation shall also be reported, such as any heating required to effect solution before titration, or end point identifieddifferent from that described in 11.7.14. Precision and Bi
27、as514.1 Table 1 is based on a round robin conducted in 1995 in accordance with Practice E180, involving two materials tested bytwelve laboratories. For each material, all the samples were prepared at one source, but the individual specimens were preparedat the laboratories that tested them. Some lab
28、oratories generated a set of results for each of two solvents (toluene and TCB), andsome laboratories generated a set of results for each of two different electrode types. Neither change in experimental conditionswas found to be a significant source of increased variability. Each of these combinatio
29、ns of conditions was treated as a differentlaboratory for purposes of calculating the precision data. Each test result was the average of two individual determinations. Eachlaboratory obtained two test results for each material for each combination of electrode and solvent used. (WarningThefollowing
30、 explanations of r and R (14.1.1 and 14.1.2) are intended only to present a meaningful way of considering theapproximate precision of this test method. The data in Table 1 should not be applied rigorously to the acceptance or rejection ofmaterial, as these data apply on to the materials tested in th
31、e round robin and may not be representative of other lots, conditions,materials, or laboratories. Users of this test method should apply the principles outlined in Practice E691 or E180 to generate dataspecific to their laboratory and materials (or between specific laboratories). The principles of 1
32、4.1.1 through 14.1.2 would then bevalid for such data.)14.1.1 Repeatability, (r)Comparing two replicates for the same material, obtained by the same operator using the sameequipment on the same day, the two replicate results should be judged not equivalent if they differ by more than the r value for
33、that material.14.1.2 Reproducibility, (R)Comparing two results, each the mean of replicates, for the same material, obtained by differentoperators using different equipment in different laboratories on different days, the two test results should be judged not equivalentif they differ by more than th
34、e R value for that material.14.1.3 Any judgment made in accordance with 14.1.1 and 14.1.2 would have an approximate 95 % (0.95) probability of beingcorrect.14.2 BiasThere are no recognized standards by which to estimate the bias of this test method.5 Supporting data have been filed at ASTM Internati
35、onal Headquarters and may be obtained by requesting Research Report RR:D20-1195.TABLE 1 RoundRobin Acidity Data in Accordance With PracticeE180Values, ppm HClAverage SrA SR B r C R D n E df FRubinate M 189 5.8 13.5 16.2 37.9 11 23Mondur MR 414 3.4 27.5 9.5 76.9 11 20A Sr = within-laboratory standard
36、 deviation of the replicates.B SR = between-laboratory standard deviation of the average.C r = within-laboratory repeatability limit = 2.8 Sr.D R = between-laboratory reproducibility limit = 2.8 SR.E n = number of laboratories contributing valid data for this material.F df = degrees of freedom in th
37、e data after incorporating multiple data sets frommost laboratories due to different combinations of solvent and electrode.D6099 13315. Keywords15.1 acidity; aromatic isocyanates; isocyanates; MDI; methylene diphenyldiisocyanate; polyurethane; raw materials; TDI;titration; toluene diisocyanateSUMMAR
38、Y OF CHANGESCommittee D20 has identified the location of selected changes to this standard since the last issue(D6099 - 03D6099) 08) that may impact the use of this standard. (November 15, 2008)(September 1, 2013)(1) Modified sampling statement in 8.1 to better reflect thoughts of industry experts.(
39、1) Replaced non-mandatory language in Revised 11.13.2.1, 13.14.1, Note 3, Note 4, and 14.1the legend forEq 1.(3) Made editorial changes in 14.1 for clarity or to remove redundancy.(4) Editorially changed 6.4 for clarity.(5) Made warning in 8.1 into a note and renumbered subsequent notes.(6) Editoria
40、lly changed 11.6 for clarity.(7) Removed footnotes 6, 7, 8. Removed unnecessary vendor-specific details.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that
41、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 years andif not revised, either reapprove
42、d 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 committee, which you may attend. If you feel
43、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 19428-2959,United States. Individual reprin
44、ts (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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D6099 134
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