ASTM_D_5155_-_14.pdf

Designation:D515514Standard Test Methods forPolyurethane Raw Materials:Determination of theIsocyanate Content of Aromatic Isocyanates1This standard is issued under the fixed designation D5155;the number immediately following the designation indicates the year oforiginal adoption 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 These test methods measure the isocyanate content ofaromatic isocyanates used as polyurethane raw materials.1.1.1 Test Method AUnheated toluene-dibutylamine deter-mines the toluene diisocyanate content,the amine equivalentand the isocyanate content of refined toluene-2,4-diisocyanateand toluene-2,6-diisocyanate,or mixtures of the two.Otherisomers,if present,will be included in the determination.Thistest method is also applicable to other isocyanates of suitablereactivity and solubility.1.1.2 Test Method BHeated toluene-dibutylamine deter-mines the amine equivalent and the isocyanate content of crudeor modified isocyanates derived from toluene diisocyanate,methylene di-(4-phenylisocyanate)and polymeric(methylenephenylisocyanate).1.1.3 Test Method CUnheated trichlorobenzene-toluene-dibutylamine determines the amine equivalent and the isocya-nate content of crude or modified isocyanates derived fromtoluene diisocyanate,methylene-di-(4-phenylisocyanate)andpolymeric(methylene phenylisocyanate).1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 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 regulatory limitations prior to use.NOTE1Method C of this test method is equivalent to Method B ofISO 14896.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1193 Specification for Reagent WaterE180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals(Withdrawn 2009)3E691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:ISO 14896 Polyurethane Raw Materials-Determination ofIsocyanate Content3.Terminology3.1 DefinitionsFor definitions of terms that appear in thistest method,refer to Terminology D883.3.2 Definitions of Terms Specific to This Standard:3.2.1 amine equivalentthe weight of sample that willcombine with 1.0-g equivalent weight of dibutylamine.3.2.2 assaythe percent by weight of toluene diisocyanatepresent in the sample.3.2.3 isocyanate(NCO)contentthe percent by weight ofNCO groups present in the sample.4.Summary of Test Methods4.1 All three test methods react the isocyanate sample withan excess amount of dibutylamine to form the correspondingurea.The NCO content is determined from the amount ofdibutylamine consumed in the reaction.The test methods differin the reaction conditions,or solvents used,or both.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 Nov.1,2014.Published November 2014.Originallyapproved in 1991.Last previous edition approved in 2010 as D5155-10.DOI:10.1520/D5155-14.2For 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 Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.1.1 Test Method AThe sample is added to an excessamount of dibutylamine in toluene and allowed to stand atroom temperature for 15 min.The reaction mixture is dilutedwith isopropyl alcohol,and the excess dibutylamine is back-titrated with hydrochloric acid.4.1.2 Test Method BThe sample is added to an excessamount of dibutylamine in toluene and stirred for 20 min.Theresulting solution is then heated rapidly to 100C,removedfrom the heat,and allowed to stand for 30 min.The reactionmixture is diluted with isopropyl alcohol,and the excessdibutylamine is back-titrated with hydrochloric acid.4.1.3 Test Method CThe sample is added to an excessamount of dibutylamine in toluene and trichlorobenzene.Theresulting solution is allowed to stand until it has cooled to roomtemperature.The reaction mixture is diluted with methanol andback-titrated with hydrochloric acid.5.Significance and Use5.1 These test methods are to be used for research or forquality control to characterize isocyanates used in polyurethanepro