1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 1242:2013Adhesives Determination ofisocyanate contentBS EN 1242:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 1242:2013. Itsupe
2、rsedes BS EN 1242:2005 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee PRI/52, Adhesives.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovi
3、sions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2013. Published by BSI StandardsLimited 2013ISBN 978 0 580 78068 4ICS 83.180Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published und
4、er the authority of theStandards Policy and Strategy Committee on 31 March 2013.Amendments issued since publicationDate Text affectedBS EN 1242:2013EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 1242 March 2013 ICS 83.180 Supersedes EN 1242:2005English Version Adhesives - Determination of isoc
5、yanate content Adhsifs - Dtermination de la teneur en isocyanate Klebstoffe - Bestimmung des Isocyanatgehaltes This European Standard was approved by CEN on 13 January 2013. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this Europ
6、ean Standard the status of a national standard without any alteration. Up-to-date 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
7、 (English, French, German). A version in any other language made by translation under 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, Bel
8、gium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switz
9、erland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. R
10、ef. No. EN 1242:2013: EBS EN 1242:2013EN 1242:2013 (E) 2 Contents Page Foreword 3 1 Scope 4 2 Normative references 4 3 Terms and definitions 4 4 Principle .4 5 Reagents 4 6 Apparatus 5 6.1 General .5 7 Procedure 5 8 Calculation and expression of the results .6 8.1 Calculation .6 8.2 Expression of re
11、sult .7 9 Precision 7 10 Test report .7 BS EN 1242:2013EN 1242:2013 (E) 3 Foreword This document (EN 1242:2013) 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 of a national standard, either
12、by publication of an identical text or by endorsement, at the latest by September 2013, and conflicting national standards shall be withdrawn at the latest by September 2013. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and
13、/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 1242:2005. The main technical significant change is: Inclusion of ethanol in the list of reagents (Clause 5) SAFETY PRECAUTIONS Persons using this document should be familiar with the
14、 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 safety and health practices and to ensure compliance with any regulatory conditions. ENVIRO
15、NMENTAL PRECAUTIONS It is understood that some of the material permitted in this document may have negative environmental impact. As technological advantages lead to acceptable alternatives for these materials, they will be eliminated from this document to the extent possible. At the end of the test
16、, the user of the document 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 organisations of the following countries are bound to implement this European Standard: Austria, Be
17、lgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
18、Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 1242:2013EN 1242:2013 (E) 4 1 Scope This European Standard specifies a method for the determination of the isocyanate content of adhesives, adhesive components and their basic constituents. It is not applicable to p
19、roducts containing blocked isocyanate groups which can be liberated by the reagents used in this test method. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edi
20、tion cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 923:2005+A1:2008, Adhesives Terms and definitions EN 1067, Adhesives Examination and preparation of samples for testing EN ISO 385, Laboratory glassware Burettes (ISO 385)
21、 EN ISO 648, Laboratory glassware Single-volume pipettes (ISO 648) EN ISO 1042, Laboratory glassware One-mark volumetric flasks (ISO 1042) EN ISO 15605, Adhesives Sampling (ISO 15605) 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 923:2005+A1:2008 an
22、d the following apply. 3.1 isocyanate content percentage (mass/mass) of isocyanate groups (-NCO) in the product under test 4 Principle A weighed quantity of product is converted in presence of an excess of dibutyl amine dissolved in toluene or another solvent forming urethanes. The unreacted dibutyl
23、 amine is backtitrated with hydrochloric acid, in the presence of a colour indicator or potentiometrically. 5 Reagents 5.1 Dibutyl amine, analytical grade or freshly distilled. NOTE As “dibutyl amine” either di-n-butylamine or di-isobutylamine can be used. 5.2 Toluene, dry, analytical grade. NOTE De
24、pending on the nature of the isocyanate other analytical grade solvents (e.g. dioxane, xylene, butane-2-one, ethyl acetate, chlorobenzene, dimethylformamide) or solvent mixtures can be used provided the product is dissolved completely without chemical reaction and it is ensured that equivalent resul
25、ts are obtained. Urethane prepolymers can be dissolved in dry toluene or xylene. When the specified conversion with dibutyl amine is completed propan-2-ol can be added before titration. BS EN 1242:2013EN 1242:2013 (E) 5 5.3 Acetone, dry, analytical grade. 5.4 Dibutyl amine 1 M concentration solution
26、 Mix thoroughly 129 g (1 mol) of dibutyl amine (see 5.1) with dry toluene (see 5.2) and dilute with toluene to 1 000 ml in a measuring flask and store in a brown, glass stoppered bottle. 5.5 Dibutyl amine 0,2 M concentration solution Mix thoroughly 25,8 g (0,2 mol) of dibutyl amine (see 5.1) with dr
27、y toluene (see 5.2) and dilute with toluene to 1 000 ml in a measuring flask and store in a brown, glass stoppered bottle. The solutions (see 5.4 and 5.5) should be kept airtight and excluded from light. As the amine content. decreases after several days of storage a blank test should be performed b
28、efore each determination. 5.6 Bromophenol blue indicator solution: Dissolve 0,1 g of bromophenol blue (Reag.Ph.Eur. Indicator grade) and dilute with ethanol (see 5.9), analytical grade, to 100 ml. NOTE Reag.Ph.Eur. = Reagent Pharmacopoeia European. 5.7 Methanol, analytical grade. 5.8 Hydrochloric ac
29、id 1,0 M/0,2 M aqueous solution, analytical grade. 5.9 Ethanol, analytical grade. 6 Apparatus 6.1 General All volumetric glassware shall be class A, in accordance with EN ISO 385, EN ISO 648 or EN ISO 1042 as appropriate. 6.2 Analytical balance, with scale divisions of 0,1 mg. 6.3 Conical flasks, ca
30、pacity 250 ml, fitted with ground glass stoppers. 6.4 Pipettes, one mark, capacity 25 ml, 50 ml or 100 ml. 6.5 Microburettes, capacity 25 ml, graduated in 0,01 ml divisions. 6.6 Device for potentiometric titration, fitted with glass electrode and a reference electrode. 6.7 Measuring, brown flasks, c
31、apacity 1 000 ml. 7 Procedure Take a sample of the product to be tested in accordance with EN ISO 15605. Examine and prepare this sample for testing in accordance with EN 1067. Weigh, to the nearest 1 mg, in one of the flasks (see 6.3) a test portion, the mass of which depends on the expected isocya
32、nate content. For testing isocyanates (e.g. TDI, MDI or HDI) with high isocyanate contents weigh a test portion of 2 g. BS EN 1242:2013EN 1242:2013 (E) 6 In testing isocyanates with low isocyanate contents (e.g. urethane prepolymers) estimate the mass of the test portion with the empirical formula:
33、(1)and use for reacting instead of a 1,0 M concentration of dibutyl amine solution (see 5.4) a 0,2 M concentration of dibutyl amine solution (see 5.5) and for backtitration 0,2 M concentration of hydrochloric acid solution (see 5.8). The approximate isocyanate content is unknown, preliminary tests s
34、hould be made. After weighing close the flask with a ground stopper to prevent the isocyanate from evaporating and reacting with atmospheric moisture. Add 20 ml of toluene (see 5.2) to the test portion and dissolve the isocyanate completely. If a polymer is insoluble, add 10 ml of dry, analytical gr
35、ade acetone (see 5.3). Solutions may be aided by warming on a hotplate. Using a pipette (see 6.4), add 25 ml of 1,0 M concentration of dibutyl amine solution (see 5.4) or 25 ml of 0,2 M concentration of dibutyl amine solution (see 5.5) depending on the isocyanate content of the product. Fill up with
36、 dry toluene (see 5.2) to a total volume of 50 ml. Swirl the flask (see 6.3) to start the reaction with the isocyanate. The reaction is complete when the liquid in the flask becomes clear, which takes about 2 min. After the addition of 2 to 3 drops of bromophenol blue indicator solution (see 5.6) di
37、lute the contents of the flask by slowly adding 100 ml of methanol (see 5.7) while the flask is being swirled. Back-titrate the excess of dibutyl amine with 1,0 M (or 0,2 M) hydrochloric acid solution (see 5.8), which is added by the microburette (see 6.5). At the end point the colour of the indicat
38、or changes from blue to yellow via an intermediate greenish colour. Record the volume (V1) used. NOTE Optionally potentiometric titration can be used. Repeat the procedure without a test portion as a blank test and record the volume (V2) used. 8 Calculation and expression of the results 8.1 Calculat
39、ion Calculate, for each test, the isocyanate content (% NCO) by the following formula: 21()% 4,2VVNCO Mm= (2) where: V1is the volume, in millilitres, of hydrochloric acid (see 5.8) used for the test portion; V2is the volume, in millilitres, of hydrochloric acid (see 5.8) used in the blank test; M is
40、 the molarity of hydrochloric acid (see 5.8); m is the mass, in grams, of the test portion. BS EN 1242:2013EN 1242:2013 (E) 7 8.2 Expression of result Take as result the mean value in at least two determinations, rounded to the next whole number. 9 Precision The maximum deviation of every single val
41、ue from the mean value should comply with the figures of Table 1. Table 1 Precision Isocyanate content (%) Maximum deviation of every single value from the mean value (relative) 10 10 % 10 to 20 5 % 20 to 30 4 % 30 to 40 3 % 40 to 50 2 % 10 Test report The test report shall include: a) reference to
42、this European Standard; b) complete identification of the sample; c) identification of the solvent used, if not toluene; d) mass in grams of the test portion and the molarity of the dibutyl amine solution used; e) the test results, the individual values and their mean; f) any special features noted
43、during the determination; g) any operations not specified in this European Standard, or the document to which reference is made, and all incidents that may have affected the results; h) date of test. This page deliberately left blankThis page deliberately left blankBSI is the independent national bo
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