1、h/-77-21 ASTM DLib65 87 W O759530 0036949 W Designation:D 4665-87 An Americen Natimi Standard AMERICAN SOCIETY FOR TESTING AND MATERIALS 1916 Race SI.,Philadelphia.Pa.19103 Reprinted from the Annual Book of ASTM Standards,Copyright ASTM If not listed in the current combined index,will appear in lhe
2、next edition.Standard Test Method for POLYURETHANE RAW MATERIALS:DETERMINATION OF ASSAY OF ISOCYANATES This standard is issued under the fixed designation D 4665;the number immediately following the designation indicates the year of original adoption or,in the case of revision.the year of last revis
3、ion.A number in parentheses indicates the year of last reapproval.A superscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope 1.I This test method determines the amount of toluene diisocyanate(TDI)in refined toluene-2,4diisocyanate and toluene-2,6diisocyanate
4、or mixtures of the two.Other isomers,if present,will be included in the determination.This test method may also be applied to other isocyanates of suitable reactivity and solubility.1.2 This standard may involve hazardous ma-terials,operations,and equipment.This standard does not purport to address
5、all o f the sajty prob-lems associated with its use.It is the responsibil-ity ofthe user ofthis standard to establish appro-priate sajty and health practices and delermine the applicability o f regulatory limitations prior to use.For specific warning and precautionary statements see Note 1.2.Referen
6、ced Documents 2.I ASTM Standards:D 84 1 Specification for Nitration Grade Tolu-D 1193 Specification for Reagent Wate3 ene2 3.Definition present in the sample.4.Summary of Test Method 4.1 The TU1 reacts with dibutylamine to form a urea.The excess amine is determined by back-titration with hydrochlori
7、c acid.5.Significance and Use 5.1 This test method can be used for research or for quality control to help determine the punty of TDI that is used in polyurethane products.3.1 assay-the percentage by weight of TDI 6.Interferences 6.1 Phosgene,the carbamoyl chloride of TDI,hydrogen chloride,and other
8、 acidic or basic com-pounds will interfere.However,in refined iso-cyanates,these compounds are usually present in such low amounts that they do not affect the determination.7.Apparatus 7.1 Lunge Pipet,or any weighing device that can weigh a liquid by difference to the nearest 7.2 Cooling-Bath-Any co
9、ntainer about 50 0.001 g.mm deep filled with ice and water.8.Reagents and Materials 8.1 Purity o f Reagents-Use reagent grade chemicals in all tests.Unless otherwise indicated,it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemi
10、cal Society where such specifications are aailabie.Other grades may be used,provided it is first ascer-tained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.I This test method is under the jurisdiction of ASTM Com-mittee D-20 on
11、Plastics and is the direct responsibility of Sub-committee D20.22 on Cellular Plastics.Cumnt edition approved Feb.27,1987.Published April 1987.Annical Book o f ASTM Standards,Vol 06.03.Annual Book o f ASTM Standards,Vol 1 1.01.Reagent Chemicals,American Chemical Society Specifi-cations.Am.Chemical S
12、oc.,Washington,DC.For suggestions on the testing of reagents not listed by the American Chemical Society,see Reagent Chemicals and Standards,by Joseph Rosin,D.Van Nostrand Co.,Inc.,New York,NY,and the United States Pharmacopeia.NOTICE:This standard has either been superseded and replaced by a new ve
13、rsion or discontinued.Contact ASTM International(www.astm.org)for the latest information.ASTM D4665 87 0759510 0036950 O 8.2 Pirriry o f Water-Unless otherwise indi-cated,references to water shall be understood to mean reagent water as defined by Type I of Specification D 1193.8.3 Bromcresol Green I
14、ndicator Soltcton-Using 1.5 mL of O.1 Nsodium hydroxide,extract the bromcresol green from O.1 O0 g of bromcresol green indicator-grade powder,stimng vigorously until the amount of insoluble residue remains constant.Decant the aqueous portion into a 100-mL volumetric flask and dilute to the mark with
15、 water.8.4 Dibrrtylamne Solution(260 g/L)-Dilute 260 g of dry dibutylamine to 1 L with dry toluene.Dry the solution with a drying agent.8.5 Hydrochloric.4cd(1 A)-Prepare 1 N HCI(hydrochloric acid)and standardize fre-quently enough to detect changes of 0.00 1 N.8.6 Isopropyl Alcohol.8.7 Tolitene.Dry-
16、Dry toluene conforming to Specification D 84 1 with a drying agent.5 9.Sampling 9.1 Since organic isocyanates react with at-mospheric moisture,take special precautions in sampling(Warning:Precaution-Note 1).Usual sampling methods(for example,sampling an open drum with a thie),even when camed out rapidly,can cause contamination of the sample with insoluble urea.Therefore,blanket the sam-ple with dry air or nitrogen at all times.NOTE 1-Warning:Organic isocyanates are toxic when they are absorbed t