1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 1245:2011Adhesives Determination of pHBS EN 1245:2011 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 1245:2011. It supersedes BS EN 1
2、245:1999, which is withdrawn.The UK participation in its preparation was entrusted to T e c h n i c a l C o m m i t t e e P R I / 5 2 , A d h e s i v e s .A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include al
3、l the necessary provisions of a contract. Users are responsible for its correct application. BSI 2011 ISBN 978 0 580 72239 4 ICS 83.180 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and
4、 Strategy Committee on 31 May 2011.Amendments issued since publicationDate T e x t a f f e c t e dBS EN 1245:2011EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 1245 April 2011 ICS 83.180 Supersedes EN 1245:1998English Version Adhesives - Determination of pH Adhsifs - Dtermination du pH Klebsto
5、ffe - Bestimmung des pH-Wertes This European Standard was approved by CEN on 10 March 2011. 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-date
6、lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre 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 un
7、der the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France
8、, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR N
9、ORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1245:2011: EBS EN 1245:2011EN 1245:2011 (E) 2 Contents Page Foreword 31 Scope 42 Normative references 43 Terms and def
10、initions .44 Principle 45 Apparatus .46 Reagents .57 Sampling .58 Procedure .69 Expression of results 710 Test report 7BS EN 1245:2011EN 1245:2011 (E) 3 Foreword This document (EN 1245:2011) has been prepared by Technical Committee CEN/TC 193 “Adhesives”, the secretariat of which is held by AENOR. T
11、his 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 October 2011, and conflicting national standards shall be withdrawn at the latest by October 2011. Attention is drawn to the possibility that some of
12、 the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 1245:1998. The main modifications regarding the previous version are in the Title, Foreword, 8.4 and Normati
13、ve References. SAFETY STATEMENT Persons using this document should be familiar with the normal laboratory practice, if applicable. 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 appropriate safe
14、ty and health practices and to ensure compliance with any regulatory conditions. ENVIRONMENTAL STATEMENT It is understood that some of the material permitted in this standard may have negative environmental impact. As technological advantages lead to acceptable alternatives for these materials, they
15、 will be eliminated from this standard to the extent possible. At the end of the test, the user of the standard should take care to carry out an appropriate disposal of the wastes, according to local regulation. According to the CEN/CENELEC Internal Regulations, the national standards organizations
16、of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Ro
17、mania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 1245:2011EN 1245:2011 (E) 4 1 Scope This European Standard specifies a method for the determination by electrometry of the pH of adhesives, their basic constituents and related products using a pH meter equipped with
18、 a glass and silver reference combined electrode. This standard is applicable to products supplied in an aqueous medium, and of known concentration, and to products which can be dissolved, dispersed or suspended in water. It is not applicable to adhesives that react with water. NOTE The accuracy of
19、the method decreases at pH values above 11. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any ame
20、ndments) applies. EN 923:2005+A1:2008, Adhesives Terms and definitions EN 1067, Adhesives Examination and preparation of samples for testing EN ISO 3696:1995, Water for analytical laboratory use Specification and test methods (ISO 3696:1987) EN ISO 15605, Adhesives Sampling (ISO 15605:2000) 3 Terms
21、and definitions For the purposes of this document, the terms and definitions given in EN 923:2005+A1:2008 and the following apply. 3.1 pH log 1/ H+ where H+ is the hydrogen ion concentration of the test sample in moles per cubic decimetres (mol/dm3) 4 Principle Measurement of the potential differenc
22、e existing between a glass electrode and a reference electrode immersed in the aqueous dispersion maintained at the specified test temperature, and reading of this difference expressed in pH units, directly on the pH meter scale. 5 Apparatus 5.1 pH meter, with input impedance of at least 1012, a res
23、olution of 0,01 pH unit, and equipped for temperature compensation. 5.2 Combined electrode, a glass electrode surrounded concentrically by a silver reference electrode. The reference electrolyte (6.3) is kept in electrical contact with the sample by a porous diaphragm. The glass electrode used shall
24、 be one recommended by the manufacturer as suitable over the pH range to be encountered. Maintain the electrodes in accordance with the manufacturers instructions. BS EN 1245:2011EN 1245:2011 (E) 5 NOTE 1 While separate electrodes can be used, it is recommended that they are replaced with combined e
25、lectrodes. For ecological reasons, silver/silver chloride electrodes are preferred to mercury/calomel electrodes. NOTE 2 The electrodes function linearly between pH 0 and the appearance of the alkaline error, which, depending on the sodium ion concentration, usually does not begin until the pH excee
26、ds 11. 5.3 Thermostatically controlled water bath, controlled to within 1 C of the specified test temperature which shall be stated. NOTE In the absence of specific temperature requirements, 23 C is the preferred temperature. 5.4 Thermometer, graduated to 0,1 C. 6 Reagents 6.1 Deionised or distilled
27、 water, complying with EN ISO 3696:1995, grade 3. 6.2 Commercially available analytical grade buffer solutions of known pH shall be used. In the absence of commercial buffer solutions, prepare the following solutions using only reagents of known analytical grade and carbon dioxide free distilled wat
28、er, or water of equivalent purity (grade 3 as defined in EN ISO 3696:1995). 6.2.1 Buffer solution of pH 7 Dissolve 3,40 g of potassium dihydrogen phosphate (KH2PO4) and 3,55 g of disodium hydrogen phosphate (Na2HPO4) in water and dilute to 1 dm3in a volumetric flask. The pH of this solution is 6,87
29、at 23 C. 6.2.2 Buffer solution of pH 4 6.2.2.1 Dissolve 10,21 g of potassium hydrogen phthalate (KOOC-C6H4-COOH) in water and dilute to 1 dm3in a volumetric flask. The pH of this solution is 4 at 23 C. 6.2.2.2 The solution shall be stored in a glass or polyethylene vessel that is resistant to chemic
30、als. After one month the solution shall be replaced. 6.2.3 Buffer solution of pH 9 6.2.3.1 Dissolve 3,814 g of sodium tetraborate decahydrate (Na2B4O710 H2O) in water and dilute to 1 dm3in a volumetric flask. The pH of this solution when freshly prepared is 9,20 at 23 C. 6.2.3.2 The solution shall b
31、e stored in a glass or polyethylene vessel that is resistant to chemicals and fitted with a soda-lime carbon dioxide trap. After one month the solution shall be replaced. NOTE Alkaline buffer solutions are unstable; they absorb carbon dioxide from the atmosphere. Where an alkaline buffer has been us
32、ed for calibration, the accuracy may be verified by means of the buffer solution of pH 4. 6.3 Reference electrolyte, 3 mol/dm3solution of potassium chloride saturated with silver chloride. 7 Sampling Take a significant sample of the adhesive to be tested, in accordance with EN ISO 15605, and prepare
33、 it, in accordance with EN 1067. BS EN 1245:2011EN 1245:2011 (E) 6 8 Procedure 8.1 General Reduction of thermal and electrical hysteresis effects, by ensuring that the temperatures of the test samples, electrodes, demineralised or distilled rinsing water and buffer solutions are as close to one anot
34、her as possible. The temperatures of the test samples and buffer solutions shall not differ by more than 1 C. 8.2 Calibration Calibrate the pH meter in accordance with the manufacturers instructions. If these are not available, proceed as follows: 8.2.1 Switch on the pH meter and allow the electroni
35、c circuit to stabilize. 8.2.2 Select two commercial buffer solutions (6.2). One at pH 7 corresponding to the zero point of the electrode and the other differing from the first by about 3 pH units and of a higher or lower pH in accordance with the sample being tested. Where commercial buffer solution
36、s are not available use the appropriate prepared buffer solutions (6.2.1 and either 6.2.2 or 6.2.3). 8.2.3 Allow the temperature of the buffer solutions, the test sample and the electrode to equilibrate in the water bath (5.3) at the specified test temperature. Record the temperature using the therm
37、ometer (5.4) and adjust the temperature correction on the pH meter correspondingly. 8.2.4 Rinse the electrode with water (6.1) and then with the buffer solution of nominal pH 7, so that the liquid runs down the length of the electrode. 8.2.5 Introduce an adequate volume of the same buffer solution i
38、nto a suitable clean, dry glass or plastic vessel and place in the water bath (5.3). Immerse the electrode in the buffer solution ensuring that the level of the reference electrolyte in the electrode remains about 5 cm higher than the level of the buffer solution (to prevent any contamination of the
39、 electrode). Stir gently and allow the reading to stabilize. Adjust the pH meter, using the zero point adjustment control, so that the reading corresponds to the pH of the buffer. Withdraw the electrode and discard the portion of that buffer solution. 8.2.6 Rinse the electrode with water (6.1) follo
40、wed by the chosen buffer solution as described in 8.2.4. NOTE Commercial buffer solution pH 10 may be available. 8.2.7 Immerse the electrode in a quantity of the chosen buffer solution as described in 8.2.5. Allow the reading to stabilize before adjusting the meter to the pH of the buffer solution u
41、sing the gradient adjustment control and without touching the zero point control. Remove the electrode and wash with water (6.1). Discard the portion of the buffer solution. NOTE Ensure that the electrode gradient is in the range - 55,6 mV/pH to - 61,5 mV/pH unit, i.e. that it is between 95 % and 10
42、3 % of the theoretical value (- 58,57 mV/pH unit at 23 C). If the electrode is outside this range refill with fresh reference electrolyte in accordance with the manufacturers instructions and repeat the calibration. 8.3 Measurement of the pH of the test sample 8.3.1 Mix the test sample thoroughly to
43、 ensure that it is homogeneous. NOTE Solid, water free or highly viscous adhesives shall be dissolved, dispersed or suspended in water in accordance with the manufacturers instructions or, if none are given, in the mass/mass ratio of 1:1. 8.3.2 Rinse the electrode and measuring vessel with water (6.
44、1) and dry with a clean soft tissue. Transfer an adequate volume into the vessel (an additional clean, dry vessel shall be used) and place it in the temperature controlled bath (5.3). Stir gently. BS EN 1245:2011EN 1245:2011 (E) 7 8.3.3 Immerse the electrode in the sample as described in 8.2.5 while
45、 maintaining the temperature at the required value. Allow the pH meter reading to stabilize and record the pH. 8.3.4 Clean the electrode by rinsing with water to remove any adhesive before it dries. 8.3.5 Repeat the operation (8.3.2 to 8.3.4) with a fresh portion of the test sample: a) if the new re
46、ading does not differ from the first by more than 0,1 pH unit, the determination is complete; b) if the readings differ by more than 0,1 pH unit make two further determinations, having first carried out all the checks necessary to detect any sources of error. If necessary, repeat b) until two consec
47、utive readings differ by less than 0,1 pH unit. 8.4 If a series of consecutive determinations is to be made, repeat the calibration of the pH meter in accordance with 8.2 at 30 min intervals, or more frequently, depending on the change found at each successive check. 9 Expression of results 9.1 Calc
48、ulate the mean of the two consecutive readings that differ by less than 0,1 pH units and round to the nearest 0,1 of a pH unit. 9.2 Express the results in units of pH at 23 C, if the determination was carried out at this temperature, otherwise specify the temperature of the determination. 10 Test re
49、port The test report shall include: a) reference to this European Standard, i.e EN 1245; b) sufficient information to identify the sample, including details of any sample preparation; c) the pH of the adhesive, calculated in accordance with Clause 9, and the temperature of the determination; d) any modification to the procedures described in this European Standard and any circumstances affecting the result; e) the date of the test. This page deliberately left blankThis page deliberately left blankBSI is the independent nati
