1、 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 1241:1998 The Europ
2、ean Standard EN 1241:1998 has the status of a British Standard ICS 83.180 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Adhesives Determination of acid valueThis British Standard, having been prepared under the direction of the Sector Board for Materials and Chemicals, was p
3、ublished under the authority of the Standards Board and comes into effect on 15 July 1998 BSI 1998 ISBN 0 580 29639 3 BS EN 1241:1998 Amendments issued since publication Amd. No. Date Text affected National foreword This British Standard is the English language version of EN 1241:1998. The UK partic
4、ipation in its preparation was entrusted to Technical Committee STI/52, Adhesives, which has the responsibility to: aid enquirers to understand the text; present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; mo
5、nitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this do
6、cument may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of
7、 British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 4, an inside back cover and a b
8、ack cover.CEN European Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1998 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN
9、 1241:1998 E EUROPEAN STANDARD EN 1241 NORME EUROPE ENNE EUROPA ISCHE NORM February 1998 ICS 83.180 Descriptors: Adhesives, components, chemical tests, determination, acidity, acid number, procedure English version Adhesives Determination of acid value Adhe sifs De termination de lindice dacidite Kl
10、ebstoffe Bestimmung der Sa urezahl This 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 standard without any alteration. Up-to-
11、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 language made by translation under t
12、he 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, Iceland, Ireland, Italy, Luxembo
13、urg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.Page 2 EN 1241:1998 BSI 1998 Foreword This European Standard has been prepared by Technical Committee CEN/TC 193, Adhesives, the secretariat of which is held by AENOR. This European Standard shall be given the status o
14、f 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 withdrawn at the latest by August 1998. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the follow
15、ing countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Contents Page Foreword 2 1 Scope 3 2 Normat
16、ive references 3 3 Definition 3 4 Principle 3 5 Safety 3 6 Reagents 3 7 Apparatus 3 8 Procedure 3 9 Calculation and expression of results 4 10 Test report 4Page 3 EN 1241:1998 BSI 1998 1 Scope This standard specifies a method for determination of the acid value of adhesives, adhesive components, the
17、ir 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 acid esters which precipitate and, are therefore, not determined. 2 Normative references Th
18、is 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 hereafter. For dated references, subsequent amendments to or revisions of any of these publi
19、cations apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 923, Adhesives Terms and definitions. EN 1066, Adhesives Sampling. EN 1067, Adhesives Examination and preparation of sam
20、ples for testing. ISO 385-1, Laboratory glassware Burettes Part 1: General requirements. ISO 648, Laboratory glassware One-mark pipettes. ISO 1042, Laboratory glassware One-mark volumetric flasks. 3 Definition For the purposes of this standard, the definitions in accordance with EN 923 and the follo
21、wing definition apply: acid value the number of milligrams of potassium hydroxide (KOH) required to neutralize 1 g of the test product under the test conditions 4 Principle A weighed quantity of product is dissolved in a mixture of solvents and the product titrated with a standardized ethanolic solu
22、tion of potassium hydroxide using a suitable indicator. 5 Safety Persons using this standard shall be familiar with normal laboratory practice. This standard does not purport to address all safety problems, if any, associated with its use. It is the responsibility of the user to establish safety and
23、 health practices and to ensure compliance with any European and national regulatory conditions. 6 Reagents 6.1 Solvent mixture: mix two parts of toluene by volume, analytical grade, and one part of ethanol by volume, analytical grade. 6.2 Thymol blue (mass concentration b = 0,1 %) indicator solutio
24、n: 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 dioxide as possible. NOTE Optionally 0,1 mol concentration in sodium hydrox
25、ide solution can be used, if required. 6.4 Acetone, analytical grade, containing less than 0,1 % (volume fraction) of water. 6.5 Nitrogen 7 Apparatus All volumetric glassware shall be class A, in accordance with ISO 385-1, ISO 648 or ISO 1042 as appropriate. 7.1 Analytical balance, with scale divisi
26、ons 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 stirrer 7.5 Source of nitrogen gas 7.6 Pipettes, one mark, capacity 50 ml. 7.7 Apparatus for potentiometric titration, optional, for example, for dark colour
27、ed solutions. 8 Procedure Take 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 g 1 mg, the quantity depending on the acid value expected. P
28、lace 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 mixture can be used provided the product is dissolved
29、 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 having a low acid number, all products covered wit
30、h nitrogen gas should be dissolved.Page 4 EN 1241:1998 BSI 1998 Shake until the product has completely dissolved, warming if necessary on a water bath with a condenser on the flask. If the solubility is poor, or if solution is incomplete after 5 min, prepare another solution by dissolving another te
31、st 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 report. 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 stre
32、am 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 for 20 to 30 s. Record the volume, V 1 , of KOH solution (see 6.3) used, in millilitres. Carry out a blank determination using 50 ml of the solvent mixture
33、 (see 6.1) or 50 ml of the solvent mixture (see 6.1) and 25 ml acetone (see 6.4)a s described above and titrate to obtain the same blue coloration as obtained when the product was present. Record the volume, V 2 , of KOH solution (see 6.3) used, in millilitres. NOTE 2 Potentiometric titration is an
34、option. 9 Calculation and expression of the results 9.1 Calculation Calculate, for each test, the acid value, A v , from the equation: A v = 56,13 M3 (V 1 2 V 2 ) m where: V 1 is the volume, in millilitres, of KOH solution (see 6.3) used to neutralize the solution of the product; V 2 is the volume,
35、in millilitres, of KOH solution (see 6.3) used in the blank determination; M is the molarity of the KOH solution (see 6.3); m is the mass, in grams, of the test portion. 9.2 Expression of results Take as the result the mean of at least two determinations, rounded to the nearest whole number. 10 Test
36、 report The 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 potentiom
37、etry); 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.blankBSI 389 Chiswick High Road London W4 4AL | |
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