1、ASTM D4bbb*E1 87 O 0759510 050b239 I 0)Designation:D 4666-87 An American Natimal Standard Standard Test Method for Polyurethane Raw Materials:Determination of Amine Equivalent Crude or Modified Isocyanates This standard is issued under the fixed designation D 4666;the number immediately following th
2、e designation indicates the year of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon(e)indicates an editorial change since the last revision or reapproval.Non-Sections 3.1 and 11.2 were correcte
3、d editorially in March 1992.1.Scope 1.1 This test method determines the amine equivalent of crude or modified isocyanates derived from toluene diisocyanate,methylene-bis-(4-phenylisocyanate),and poly-methylene polyphenylisocyanate.1.2 This standard may involve hazardous materials,oper-ations,and equ
4、ipment.This standard does not purport to address all o f the safety problems associated with its use.It is the responsibility o f the user o f this standard to establish appropriate safety and health practices and determine the applicability o f regulatory limitations prior to use.For specific warni
5、ng and precautionary statements see Note 1.2.Referenced Documents 2.1 ASTM Standards:D 84 1 Specification for Nitration Grade Toluene2 D 1 193 Specification for Reagent Water3 3.Summary of Test Method 3.1 The isocyanate groups present react with an excess of di-n-butylamine to form ureas.The excess
6、amine is titrated potentiometrically with standard hydrochloric acid.The amine equivalent is defined as the weight of sample that will combine with 1.O-g equivalent weight of dibutylamine.The percent NCO can also be calculated as shown in 11.1.4.Significance and Use 4.1 This test method can be used
7、for research or for quality control to characterize isocyanates used in poly-urethane products.5.Interferences 5.1 Phosgene,the carbamyl chloride of the isocyanate,hydrogen chloride,and any other acidic or basic compounds will interfere.While some crude or modified isocyanates contain acidities of u
8、p to about 0.3%,the NCO or amine equivalent is not normally corrected.I This test method is under the jurisdiction of ASTM Committee D-20 on Plastics and is the direct responsibility of Subcommittee D20.22 on Cellular Plastics.Current edition approved Feb.27,1987.Published April 1987.Originally publ
9、ished as part of D 1638-59 T.Last previous edition D 1638-74.Annual Book o f ASTM Standards,Vol 06.03.Annual Book ofASTiMSfandards,Vols 02.05,09.01,10.02,1 1.0 1 and 11.03.6.Apparatus 6.1 Potentiometric Titrator,or pH meter.6.2 Calomel Electrode.6.3 Glass Electrode.6.4 Lunge Pipet,or any weighing de
10、vice suitable for weighing a liquid sample by difference to the nearest 0.00 1 g.6.5 Magnetic Stirrer.6.6 Thermometer,-10 to 100C range.7.Reagents and Materials 7.1 Purity o f Reagents-Use reagent grade chemicals in ali tests,Unless otherwise indicated,all reagents shall con-form to the specificatio
11、ns of the Committee on Analytical Reagents of the American Chemical Society where such specifications are available.“Other grades may be used provided it is first ascertained that the reagent is of sufi-ciently high purity to permit its use without lessening the accuracy of the determination.7.2 Pur
12、ity o f Water-Unless otherwise indicated,refer-ences to water shali be understood to mean reagent water as defined by Type I of Specification D 1193.7.3 Dibutylamine Solution(260 g/L)-Dilute 260 g dry dibutylamine to 1 L with dry toluene.7.4 Hydrochloric Acid(1 N)-Prepare 1 N hydrochloric acid(HC1)a
13、nd standardize frequently enough to detect changes of 0.00 1.7.5 Isopropyl Alcohol,99%minimum purity.7.6 Toluene,dry,in accordance with Specification D 84 1,and dried by a drying agent.8.Sampling 8.1 Since organic isocyanates react with atmospheric moisture,take special precautions in sampling(Warni
14、ng:Precaution-Note 1).Usual sampling methods(for example,sampling an open drum with a thief),even when carried out rapidly,can cause contamination of the sample with insol-uble urea.Therefore,blanket the sample with dry air or nitrogen at all times.NOTE 1:Warning-Organic isocyanates are toxic when t
15、hey are absorbed through the skin,or when the vapors are breathed.Precau-4“Reagent Chemicals,American Chemical Society Specificafions,”Am.Chem-ical Soc.,Washington,DC.For suggestions on the testing of reagents not listed by the American Chemical Society,see“Reagent Chemicals and Standards,”by Joseph
16、 Rosin,D.Van Nostrand Co.,rnc.,New York,NY,and the“United States Pharmacopeia.”584 NOTICE:This standard has either been superseded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.ASTM DLibbbnEL 87 0759530 050b240 B D4666 tion-Provide adequate ventilation and wear protective gloves and eyeglasses.9.Test Conditions humidity low,preferably around 50%relative humidity.10.Procedure 1 O.1 Add 50 mL of dry toluene to a dry 600-mL beaker.P
