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1、豆丁网：http:/ STANDARDAdhesives Determination of acid valueThe European Standard EN 1241:1998 has the status of aBritish StandardICS 83.180| BS EN1241:1998|第 5 页 共 13 页豆丁网：http:/ Copy: sheffieldun sheffieldun, na, Sat Oct 28 09:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI|NO COPYING WITHOUT BSI PER
2、MISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS EN 1241:1998National forewordThis British Standard is the English language version of EN 1241:1998.The UK participation in its preparation was entrusted to Technical CommitteeSTI/52, Adhesives, which has the responsibility to: aid enquirers to understan
3、d the text; present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK.A list of organizations represented on this committee can
4、be obtained on request to its secretary.Cross-referencesThe British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled International Standards Correspondence Index, or by using theFind f
5、acility of the BSI Standards Electronic Catalogue.A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application.Compliance with a British Standard does not of itself confer immunity from legal oblig
6、ations.Summary of pagesThis document comprises a front cover, an inside front cover, the EN title page, pages 2 to 4, an inside back cover and a back cover.Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 09:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSIAmd. No.DateText affectedThis British
7、Standard, having been prepared under the direction of the Sector Board for Materials and Chemicals, was published under the authority of the Standards Board and comes into effect on 15 July 1998BSI 1998ISBN 0 580 29639 3Amendments issued since publicationLicensed Copy: sheffieldun sheffieldun, na, S
8、at Oct 28 09:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSIEUROPEAN STANDARDEN 1241NORME EUROPE ENNEEUROPA ISCHE NORMFebruary 1998ICS 83.180Descriptors: Adhesives, components, chemical tests, determination, acidity, acid number, procedureEnglish versionAdhesives Determination of acid valueAdhe sif
9、s De termination de lindice daciditeKlebstoffe Bestimmung der Sa urezahlThis European Standard was approved by CEN on 2 January 1998.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national sta
10、ndard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other l
11、anguage made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece
12、, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.CENEuropean Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r NormungCentral Secretariat: rue de Stassart 36, B-1050 Brussels1998 CEN All right
13、s of exploitation in any form and by any means reserved worldwide for CEN nationalMembers.Ref. No. EN 1241:1998 EPage EN 1241:1998BSI 1998ForewordThis European Standard has been prepared byTechnical Committee CEN/TC 193, Adhesives, theContentsPageLicensed Copy: sheffieldun sheffieldun, na, Sat Oct 2
14、8 09:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSIsecretariat of which is held by AENOR.This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by August 1998, and conflicting national standards shall be
15、withdrawn at the latest by August 1998.According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Ital
16、y, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.Foreword 21Scope 32Normative references 33Definition 34Principle 35Safety 36Reagents 37Apparatus 38Procedure 39Calculation and expression of results 410Test report 4Page 3EN 1241:19981 ScopeThis standard
17、specifies a method for determination of the acid value of adhesives, adhesive components, their basic constituents, and related products.In some cases, notably when unsaturated polyesters with free anhydrides are present, somewhat lower than theoretical acid values are found, due to the formation of
18、 acid esters which precipitate and, are therefore, not determined.2 Normative referencesThis European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed he
19、reafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard onlywhen incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies.EN 923, Adhesives Terms and definit
20、ions. EN 1066, Adhesives Sampling.EN 1067, Adhesives Examination and preparation of samples for testing.ISO 385-1, Laboratory glassware Burettes Part 1: General requirements.ISO 648, Laboratory glassware One-mark pipettes. ISO 1042, Laboratory glassware One-markvolumetric flasks.3 DefinitionFor the
21、purposes of this standard, the definitions in accordance with EN 923 and the following definition apply:acid valuethe number of milligrams of potassium hydroxide (KOH) required to neutralize 1 g of the test product under the test conditions4 PrincipleA weighed quantity of product is dissolved in a m
22、ixture of solvents and the product titrated with astandardized ethanolic solution of potassium hydroxide using a suitable indicator.5 SafetyPersons using this standard shall be familiar with normal laboratory practice.This standard does not purport to address all safety problems, if any, associated
23、with its use.It is the responsibility of the user to establish safety and health practices and to ensure compliance with any European and national regulatory conditions.6 Reagents6.1 Solvent mixture: mix two parts of toluene by volume, analytical grade, and one part of ethanol by volume, analytical
24、grade.6.2 Thymol blue (mass concentration b = 0,1 %) indicator solution: dissolve 0,1 g of Thymol blue in ethanol, analytical grade, and dilute to 100 ml.6.3 Potassium hydroxide (KOH), 0,1 mol concentration, in ethanol, analytical grade. The solution shall be anhydrous and as free from carbon dioxid
25、e as possible.NOTE Optionally 0,1 mol concentration in sodium hydroxide solution can be used, if required.6.4 Acetone, analytical grade, containing less than0,1 % (volume fraction) of water.6.5 Nitrogen7 ApparatusAll volumetric glassware shall be class A, in accordance with ISO 385-1, ISO 648 or ISO
26、 1042 as appropriate.7.1 Analytical balance, with scale divisions of 0,1 mg.7.2 Conical flasks, capacity 250 ml, with large neck.7.3 Burette, capacity 50 ml, graduated in 0,05 ml divisions.7.4 Magnetic stirrer7.5 Source of nitrogen gas7.6 Pipettes, one mark, capacity 50 ml.7.7 Apparatus for potentio
27、metric titration, optional, for example, for dark coloured solutions.8 ProcedureTake a sample of the product to be tested in accordance with EN 1066. Examine and prepare this sample for testing in accordance with EN 1067.Weigh, to the nearest 1 mg, a test portion in the range of 0,5 g to 3,0 g1 mg,
28、the quantity depending on the acid value expected.Place this test portion in one of the flasks (see 7.2)and add 50 ml of the solvent mixture (see 6.1), using a pipette (see 7.6).NOTE 1 Depending on the nature of the product under test other suitable solvents, e.g. dimethyl-formamide, or solvent mixt
29、ure can be used provided the product is dissolved completely without chemical reaction.For water-borne adhesives no solvent is required and aqueous standard volumetric potassium hydroxide solution free from carbon dioxide may be used. To avoid an excess of carbon dioxide, particularly to products ha
30、ving a low acid number, all products covered with nitrogen gas should be dissolved.Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 09:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSIBSI 1998Page EN 1241:1998BSI 1998Shake until the product has completely dissolved, warming if necessary on a wa
31、ter bath with a condenser on the flask. If the solubility is poor, or if solution is incomplete after 5 min, prepare anothersolution by dissolving another test portion in a mixture of 50 ml of the solvent mixture (see 6.1) and 25 ml acetone (see 6.4). Record this change in procedure in the test repo
32、rt.Cool the solution to (23 2) 8C.Add 5 drops of thymol blue solution (see 6.2). Place the flask on the magnetic stirrer and bubble into the solution a stream of nitrogen.Titrate with the potassium hydroxide solution (see 6.3) from the burette (see 7.3) to the endpoint where the colour remains blue
33、for 20 to 30 s. Record thevolume, V1, of KOH solution (see 6.3) used, in millilitres.Carry out a blank determination using 50 ml of the solvent mixture (see 6.1) or 50 ml of the solvent mixture (see 6.1) and 25 ml acetone (see 6.4) as described above and titrate to obtain the same blue coloration as
34、 obtained when the product was present. Record the volume, V2, of KOH solution (see 6.3) used, in millilitres.NOTE 2 Potentiometric titration is an option.9 Calculation and expression of the results9.1 CalculationCalculate, for each test, the acid value, Av , from the equation:vA = 56,1 3 M 3 (V1 2
35、V2)m10 Test reportThe test report shall include:a) a reference to this European Standard;b) a complete identification of the sample;c) identification of the solvent used for solution preparation, i.e. toluene/ethanol or toluene/ ethanol/acetone and the end point detection used (by an indicator or po
36、tentiometry);d) test results, the individual acid values and their mean;e) any special features noted during the determination;f) any operations not specified in this European Standard and all incidents that may have affected the results;g) date of test.Licensed Copy: sheffieldun sheffieldun, na, Sa
37、t Oct 28 09:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSIwhere:V1 is the volume, in millilitres, of KOH solution (see 6.3) used to neutralize the solution of the product;V2 is the volume, in millilitres, of KOH solution(see 6.3) used in the blank determination;M is the molarity of the KOH solutio
38、n (see 6.3);m is the mass, in grams, of the test portion.9.2 Expression of resultsTake as the result the mean of at least two determinations, rounded to the nearest whole number.blankLicensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 09:00:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSIBSI389 Chis
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