1、Designation:D466315Standard Test Method forPolyurethane Raw Materials:Determination of HydrolyzableChlorine of Isocyanates1This standard is issued under the fixed designation D4663;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the
2、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 hydrolyzable chlorinecontent of toluene-2,4-diisocyanate,toluene-2,6-diisocyanate,
3、or mixtures of the two.It is acceptable to apply this test methodto other isocyanates of suitable solubility.(See Note 1.)Themain sources of hydrolyzable chlorine in the isocyanates arecarbamoyl chloride and dissolved phosgene.Both of thesecompounds react with alcohols and water,forming ureas,carbam
4、ates,carbon dioxide,and hydrochloric acid.(See Note2.)1.2 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 establish appro-priate safety and health practices and determine the applica-bility of
5、regulatory limitations prior to use.NOTE1It is possible that this test method is applicable to crudepolymeric isocyanates.However,the precision with crude polymericisocyanates has not been established.NOTE2This standard is identical to ISO 15028.2.Referenced Document2.1 ASTM Standards:2D883 Terminol
6、ogy Relating to PlasticsD1193 Specification for Reagent Water2.2 ISO Standards:ISO 15028 PlasticsAromatic Isocyanates for Use in theProduction of PolyurethanesDetermination of Hydroly-sable Chlorine33.Terminology3.1 DefinitionsFor definitions of terms used in this testmethod see Terminology D883.3.2
7、 Definitions of Terms Specific to This Standard:3.2.1 hydrolyzable chloridethe low level chlorine-containing components of the isocyanate,such as carbamoylchlorides,which react with water or alcohol to form HCl.4.Summary of Test Method4.1 The hydrolyzable chlorine reacts with methanol,liber-ating hy
8、drochloric acid.The titratable chlorides are thendetermined potentiometrically using a standard silver nitratesolution.5.Significance and Use5.1 This test method can be used for research or for qualitycontrol to characterize toluene diisocyanates.Hydrolyzablechlorine correlates with performance in s
9、ome polyurethanesystems.6.Interferences6.1 Thiocyanate,cyanide,sulfide,bromide,iodide,or othersubstances capable of reacting with silver ions,as well assubstances capable of reducing silver ions in acid solution,willinterfere with the determination.7.Apparatus7.1 Weighing Bottle,or any device capabl
10、e of weighing aliquid by difference to the nearest 0.1 g.7.2 Hot Plate,with magnetic stirrer.7.3 Potentiometric Titrator,or pH meter.7.4 Combination Silver Billet Electrode.8.Reagents and Materials8.1 Purity of ReagentsUse reagent grade chemicals in alltests.Unless otherwise indicated,it is intended
11、 that all reagentsconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society where such1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.22 on Cellular Materials-Plastics and El
12、astomers.Current edition approved May 1,2015.Published June 2015.Originallyapproved in 1987.Last previous edition approved in 2010 as D4663-10.DOI:10.1520/D4663-15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of
13、 ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM I
14、nternational,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 specifications are available.4Other grades may be used,pro-vided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.8
15、.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water as definedby Type I of Specification D1193.8.3 Concentrated Nitric Acid(HNO3sp gr 1.42).8.4 Methanol.8.5 Silver Nitrate Standard Solution(0.01 N)Standardizewith standard hydrochloric acid,either
16、 gravimetrically orpotentiometrically,frequently enough to detect changes of0.0005 N.9.Sampling9.1 Since organic isocyanates react with atmosphericmoisture,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 nitrogen at all times.(WarningDiisocyanates are eye,skin and respiratory irritants at concen-trations above the occupational exposure limit(TLV or PEL).Di
