1、BS ISO 14900:2017Plastics Polyols for use in theproduction of polyurethane Determination of hydroxylnumberBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 14900:2017 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 14900:20
2、17. It supersedes BS ISO 14900:2001 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee PRI/42, Fibre reinforced thermosetting plastics and prepregs.A list of organizations represented on this committee can be obtained on request to its secretary.This publ
3、ication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017.Published by BSI Standards Limited 2017ISBN 978 0 580 96054 3 ICS 83.080.10 Compliance with a British Standard cannot confer immun
4、ity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 March 2017.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 14900:2017 ISO 2017Plastics Polyols for use in the production of polyure
5、thane Determination of hydroxyl numberPlastiques Polyols pour la production du polyurthanne Dtermination de lindice dhydroxyleINTERNATIONAL STANDARDISO14900Second edition2017-03Reference numberISO 14900:2017(E)BS ISO 14900:2017ISO 14900:2017(E)ii ISO 2017 All rights reservedCOPYRIGHT PROTECTED DOCUM
6、ENT ISO 2017, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written p
7、ermission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 14900:2017ISO 1
8、4900:2017(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Principle 25 Interferences 26 Reagents 27 Apparatus . 48 Method A Acetylation . 58.1 Procedure 58.2 Expression of results 78.3 Precision and bias 78.4 Test report . 89 Method B Phthalation 89.1 Proce
9、dure 89.2 Expression of results 99.3 Precision and bias . 109.4 Test report 10Bibliography .12 ISO 2017 All rights reserved iiiContents PageBS ISO 14900:2017ISO 14900:2017(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO m
10、ember bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governm
11、ental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenanc
12、e are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).Attenti
13、on is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction a
14、nd/or on the ISO list of patent declarations received (see www .iso .org/ patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformi
15、ty assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www .iso .org/ iso/ foreword .html.This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 12, Th
16、ermosetting materials.This second edition cancels and replaces the first edition (ISO 14900:2001), of which it constitutes a minor revision. It also incorporates the Technical Corrigendum ISO 14900:2001/Cor. 1:2005. The changes compared to the previous edition are as follows: in Clause 2, the normat
17、ive references have been updated; in Clause 4, it has been clarified that Method A refers to “acetylation” and Method B refers to “phthalation”.iv ISO 2017 All rights reservedBS ISO 14900:2017ISO 14900:2017(E)IntroductionInternational Standards have been published which deal with the determination o
18、f hydroxyl values of unsaturated-polyester resins (ISO 2554), non-ionic surface active agents (ISO 4326, ISO 4327), binders for paints and varnishes ISO 4629 (all parts) and industrial polyglycols (ISO 6796). The two methods in this document are improved versions of imidazole-catalyzed procedures sp
19、ecifically tailored to the determination of the hydroxyl number of many types of polyol, including those used in the production of polyurethanes. Method A is especially suited to the determination of the hydroxyl number of polyether polyols that may have steric hindrance, or are otherwise difficult
20、to determine by phthalation. Method B is a general method based on phthalation and is applicable to a wide range of polyol types. Both of these methods are similar to procedures found in ASTM D4274. ISO 2017 All rights reserved vBS ISO 14900:2017BS ISO 14900:2017Plastics Polyols for use in the produ
21、ction of polyurethane Determination of hydroxyl numberWARNING Persons using this document should be familiar with normal laboratory practice. This document does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appro
22、priate safety and health practices and to ensure compliance with any national regulatory conditions.1 ScopeThis document specifies two methods for the measurement of the hydroxyl number of polyols used as polyurethane raw materials. It is necessary to know the hydroxyl content of polyols to properly
23、 formulate polyurethane systems. Method A is primarily applicable to readily esterified polyether polyols. It is also intended for polyols which have significant steric hindrance, such as those based on sugars. Method B is intended for polyether polyols, polymer polyols and amine-initiated polyols,
24、but may give low results for sterically hindered polyols. Other polyols can be analysed by these methods if precautions are taken to verify applicability. These methods can be used for research and for quality control and specification purposes.2 Normative referencesThe following documents are refer
25、red to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 385, Laboratory glassware B
26、urettesISO 648, Laboratory glassware Single-volume pipettesISO 760, Determination of water Karl Fischer method (General method)ISO 835, Laboratory glassware Graduated pipettesISO 3696, Water for analytical laboratory use Specification and test methodsISO 4788, Laboratory glassware Graduated measurin
27、g cylindersISO 6353-1, Reagents for chemical analysis Part 1: General test methodsISO 6353-2, Reagents for chemical analysis Part 2: Specifications First seriesISO 6353-3, Reagents for chemical analysis Part 3: Specifications Second series3 Terms and definitionsFor the purposes of this document, the
28、 following terms and definitions apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p :/ www .iso .org/ obpINTERNATIONAL STANDARD
29、 ISO 14900:2017(E) ISO 2017 All rights reserved 1BS ISO 14900:2017ISO 14900:2017(E)3.1polyurethanepolymer prepared by the reaction of an organic di- or polyisocyanate with compounds containing two or more hydroxyl groups3.2hydroxyl numberhydroxyl valuenumber of milligrams of potassium hydroxide equi
30、valent to the hydroxyl content of 1 g of a test portion4 Principle4.1 Method A (Acetylation): A test portion is refluxed in a solution of acetic anhydride in pyridine to acetylate the hydroxyl groups present; the reaction is catalyzed by imidazole. The excess reagent is hydrolyzed with water and the
31、 resulting acetic acid is titrated with standardized sodium hydroxide solution. The hydroxyl content is calculated from the difference in titration of the test portion and a blank solution.CAUTION Acetic anhydride and pyridine are toxic and flammable. In addition, acetic anhydride is corrosive. Take
32、 proper precautions when handling these reagents.4.2 Method B (Phthalation): The hydroxyl groups in a test portion are esterified by refluxing with a solution of phthalic anhydride in pyridine; the reaction is catalyzed by imidazole. The excess anhydride is hydrolyzed with water and the phthalic aci
33、d formed is titrated with standardized sodium hydroxide solution. The hydroxyl content is calculated from the difference in titration of the test portion and a blank solution.5 Interferences5.1 Excess water will interfere by destroying part of the esterification reagent. If the sample contains more
34、than 0,2 % water, dry the sample with a reagent that will not add acidity or basicity to the sample.5.2 Primary and secondary amines and long-chain fatty acids react with the reagent to form stable compounds that will be included in the result.6 ReagentsReagent-grade chemicals shall be used in all d
35、eterminations. Unless otherwise indicated, it is intended that all reagents conform to the specifications of ISO 6353-1, ISO 6353-2 and ISO 6353-3, although other grades may be used provided that it is first determined that the reagent is of sufficiently high purity to permit its use without lesseni
36、ng the accuracy of the determination.Unless otherwise indicated, references to water shall be understood to mean grade 2 reagent water as defined by ISO 3696.6.1 Acetylation reagent (for method A).Mix 127 ml of acetic anhydride with 1 000 ml of dry pyridine (6.7). Add 16 g of imidazole (6.3) and swi
37、rl carefully to dissolve. Prepare the reagent fresh daily and keep it in a dark bottle. Do not use it if it is darker than pale yellow.NOTE Some laboratories have reported that dark, resinous solids have formed when the mixture of pyridine and esterification reagent is heated. In that event, it has
38、been found that preparing the acetylation reagent with the addition of 0,4 % water in the pyridine (6.8) will correct the problem. However, care has to be taken that sufficient reagent is present to complete the reaction quantitatively. See also 8.1.2.2 ISO 2017 All rights reservedBS ISO 14900:2017I
39、SO 14900:2017(E)CAUTION Acetic anhydride and pyridine are eye, skin, and respiratory irritants. Avoid bodily contact with these reagents and use only in a well-ventilated area.6.2 Phthalation reagent (for method B).Weigh 116 g of phthalic anhydride into a 1 l brown bottle. Add 700 ml of pyridine (6.
40、7) and shake vigorously until dissolved. Add 16 g of imidazole and swirl carefully to dissolve. The reagent shall stand overnight before use. Avoid prolonged exposure of the reagent to moisture in the air. Discard reagent that develops a colour. In the blank titration as described in the procedure f
41、or method B, exactly 25 ml of this reagent shall consume between 95 ml and 100 ml of 0,500 mol/l sodium hydroxide.6.3 Imidazole, reagent grade or equivalent.6.4 Hydrochloric acid, standard solution, 0,1 mol/l.Prepare and standardize to four significant figures in accordance with good practice, using
42、 potassium acid phthalate (6.6) as a primary standard. Determine and record the temperature at which the standardization was performed. The concentration of the solution shall be corrected to the temperature at which the determination is performed, as described in 6.9. This solution is required only
43、 if a correction is to be applied for the presence of strong base in the sample being analysed.6.5 Phenolphthalein indicator solution, 10 g/l.Prepare a solution of 1 g of phenolphthalein in 100 ml of pyridine (6.7).6.6 Potassium acid phthalate.Use a certified primary standard.6.7 Pyridine, reagent g
44、rade, containing less than 0,1 % water.If purification is required, distil from phthalic anhydride, discarding the fraction boiling below 114 C to 115 C.6.8 Pyridine, containing from 0,30 % to 0,45 % water (used for special cases: see the note to 6.1).Determine the water content of the pyridine usin
45、g ISO 760. Add the required amount of water. The required volume of water to add per litre of pyridine may be calculated as follows:Water to add, in ml = 4,0 9Awhere A is the percent water already in the pyridine.6.9 Sodium hydroxide, standard solution, 0,5 mol/l.Prepare and standardize to four sign
46、ificant figures in accordance with good practice. Determine and record the temperature at which the standardization was performed. The factor for thermal expansion of this solution is 0,000 14. For calculation of the hydroxyl content, the concentration of the solution shall be corrected to the tempe
47、rature at which the determination was performed by the following:c2= c1+ F(1 2) ISO 2017 All rights reserved 3BS ISO 14900:2017ISO 14900:2017(E)wherec1is the concentration of the solution when standardized, in mol/l;c2is the concentration during analysis of samples, in mol/l;1is the temperature of t
48、he solution during standardization, in C;2is the temperature of the solution during analysis of samples, in C;F is the factor to correct for thermal expansion of the solution.7 Apparatus7.1 Potentiometric titrator or pH-meter, accurate to 0,1 mV or better, equipped with a pair of electrodes or a com
49、bination glass-calomel electrode and a piston burette having a 100 ml capacity or capability for multiple automatic refilling.7.2 Syringes, 2 ml, 5 ml and 10 ml, with an orifice suitable for handling viscous polyols.7.3 Magnetic stirrer.7.4 Analytical balance, accurate to 0,1 mg.7.5 Volumetric pipette, 20 ml, conforming to ISO 648.7.6 Measuring pipette, 1 ml, conforming to ISO 835.7.7 Graduated cylinder, 100 ml, conforming to ISO 4788.7.8 Beakers, 250 ml, 500 ml.7.9 Burette (for colorim
