1、Designation: D 4663 98 (Reapproved 2004)Standard Test Method forPolyurethane Raw Materials: Determination of HydrolyzableChlorine of Isocyanates1This standard is issued under the fixed designation D 4663; the number immediately following the designation indicates the year oforiginal adoption or, in
2、the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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-diisoc
3、yanate, toluene-2,6-diisocyanate,or mixtures of the two. This test method may also be applied toother isocyanates of suitable solubility. (See Note 1.) The mainsources of hydrolyzable chlorine in the isocyanates are car-bamoyl chloride and dissolved phosgene. Both of these com-pounds react with alco
4、hols and water, forming ureas, carbam-ates, carbon dioxide, and hydrochloric acid. (See Note 2.)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 p
5、ractices and determine the applica-bility of regulatory limitations prior to use.NOTE 1This test method may be applicable with crude polymericisocyanates. However, the precision with crude polymeric isocyanates hasnot been established.NOTE 2There is no equivalent ISO standard.2. Referenced Document2
6、.1 ASTM Standards:2D 883 Terminology Relating to PlasticsD 1193 Specification for Reagent Water3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod see Terminology D 883.3.2 Description of Term Specific to This Standard.3.2.1 hydrolyzable chloridethe low level chlorine-conta
7、ining 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 hydrochloric acid. The titratable chlorides are thendetermined potentiometrically using a standard si
8、lver 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 some polyurethanesystems.6. Interferences6.1 Thiocyanate, cyanide, sulfide, bromide, iodide, or o
9、thersubstances capable of reacting with silver ion, as well assubstances capable of reducing silver ion in acid solution, willinterfere with the determination.7. Apparatus7.1 Weighing Bottle, or any device capable of weighing aliquid by difference to the nearest 0.1 g.7.2 Hot Plate, with magnetic st
10、irrer.7.3 Potentiometric Titrator, or pH meter.7.4 Silver-Silver Chloride Electrode.7.5 Silver or Glass Electrode.7.6 Calomel Electrode.8. Reagents and Materials8.1 Purity of ReagentsUse reagent grade chemicals in alltests. Unless otherwise indicated, it is intended that all reagentsconform to the s
11、pecifications 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 Plastics.Current edition approved March 1, 2004. Published
12、June 2004. Originallyapproved in 1987. Last previous edition approved in 1998 as D 4663 - 98.2For 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
13、Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.specifications are available.3Other grades may be used, pro-vided it is first ascertain
14、ed that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type I of Specification D 1193.8.3 Concentrated Nitric Acid
15、(HNO3sp gr 1.42).8.4 Methanol.8.5 Silver Nitrate Standard Solution (0.01 N)Standardizewith standard hydrochloric acid, either gravimetrically orpotentiometrically, frequently enough to detect changes of0.0005 N.9. Sampling9.1 Since organic isocyanates react with atmospheric mois-ture, take special p
16、recautions in sampling. Usual samplingmethods (for example, sampling an open drum with a thief),even when carried out rapidly, can cause contamination of thesample with insoluble urea. Therefore, blanket the sample withdry air or nitrogen at all times. WarningOrganic isocyanatesare toxic when they a
17、re absorbed through the skin, or when thevapors are breathed. Provide adequate ventilation and wearprotective gloves and eyeglasses.NOTE 3Warning:10. Test Conditions10.1 Since isocyanates react with moisture, keep laboratoryhumidity low, preferably around 50 % relative humidity.11. Procedure11.1 Wei
18、gh (by difference to the nearest 0.1 g) 9 to 11 g ofsample from a sampling weighing bottle into a clean, dry400-mL beaker (Note 4). Add 50 mL of methanol and stir. Stircontinually while the reaction starts at which point the beakerwill become warm and crystals may form on the sides of thebeaker (Not
19、e 5). Fill the beaker half-full with water (Note 6)and boil gently for 30 min.NOTE 4If the hydrolyzable chlorine content is expected to be lessthan 0.01 %, use 18 to 22 g of sample.NOTE 5Some isocyanates will not react readily and slight warmingmay be necessary to initiate reaction. Other isocyanate
20、s may react, asindicated by warming of reactants, but may not form crystals.NOTE 6Add the water quickly to keep the reactants from solidifyingand to minimize the loss of HCl.11.2 Wash the sides of the beaker with water and removeand wash the stirring bar. Cool the beaker in an ice bath toabout 10C a
21、nd add 10 drops of HNO3. Titrate potentiometri-cally with 0.01 N AgNO3solution using a silver-silver chlorideelectrode pair. If the chloride content is greater than 0.2 %, use0.1 N instead of 0.01 N AgNO3solution.12. Calculation12.1 Calculate the hydrolyzable chlorine as weight percentas follows:Hyd
22、rolyzable chlorine, %53.55AN/Wwhere:A = AgNO3solution required for titration of the sample, mL,N = normality of the AgNO3solution, meq/mL,W = sample used, g, and3.55 = constant combining the atomic weight of chlorine (35.5), mg, the con-version from milligrams to grams (1000), and conversion to perc
23、ent(100).Hydrolyzable chlorine, % = 35.5AN(100)/1000W = 3.55AN/W13. Precision and Bias13.1 PrecisionAttempts to develop a precision and biasstatement for this test method have not been successful due tothe limited number of laboratories participating in round-robintests. Data on precision and bias c
24、annot be given for thisreason. Anyone wishing to participate in the development ofprecision and bias data should contact the Chairman, Subcom-mittee D20.22 (Section D20.22.01), ASTM, 100 Barr HarborDrive, West Conshohocken, PA 19428.13.2 A limited round-robin was conducted.13.2.1 It has been estimat
25、ed that duplicate results by thesame analyst should be considered suspect if they differ bymore than 0.001 % hydrolyzable chlorine at the 0.001 to 0.2 %level.13.2.2 It has been estimated that results reported by differentlaboratories should be considered suspect if they differ by morethan 0.003 % hy
26、drolyzable chlorine.13.3 BiasThere are no recognized standards by which toestimate the bias of this test method.14. Keywords14.1 aromatic isocyanates; hydrolyzable chlorine; isocyan-ates; polyurethane raw materials; titration; toluene diisocyanate3Reagent Chemicals, American Chemical Society Specifi
27、cations, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convent
28、ion, Inc. (USPC), Rockville,MD.D 4663 98 (2004)2SUMMARY OF CHANGESThis section identifies the location of selected changes to this test method. For the convenience of the user,Committee D20 has highlighted those changes that impact the use of this test method. This section also includesdescriptions
29、of the changes or reasons for the changes, or both.D 4663 - 98 (2004): (1) Reapproved without change.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 det
30、ermination 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 reapproved o
31、r 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 th
32、at 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 reprints (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).D 4663 98 (2004)3
