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1、BRITISH STANDARD BS EN ISO 9020:1998 BS 6782-7: 1996 Implementing Amendment No. 1 to BS 6782-7:1996 (renumbers the BS as BE EN ISO 9020:1998), not published separately Binders for paints and varnishes Determination of free-formaldehyde content of amino resins Sodium sulfite titrimetric method ICS 87
2、.060.20 BS EN ISO 9020:1998 This British 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 November 1996 BSI 05-1999 First published as BS 6782-7 December 1995 Secon
3、d edition November 1996 The following BSI references relate to the work on this standard: Committee reference STI/3 Draft for comment 87/51726 DC ISBN 0 580 26490 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee STI/3, P
4、aints, media and related products, upon which the following bodies were represented: British Coatings Federation Ltd. European Resin Manufacturers Association FOSFA International Ministry of Defence Oil and Colour Chemists Association Seed Crushers and Oil Processors Association Amendments issued si
5、nce publication Amd. No.DateComments 10177October 1998Indicated by a sideline in the margin BS EN ISO 9020:1998 BSI 05-1999i Contents Page Committees responsibleInside front cover National forewordii Foreword2 1Scope3 2Normative references3 3Principle3 4Reagents and materials3 5Apparatus4 6Sampling4
6、 7Procedure4 8Expression of results5 9Test report6 Annex ZA (normative) Normative references to International publications with their relevant European publications7 Table 1 Mass of test portion4 List of referencesInside back cover BS EN ISO 9020:1998 ii BSI 05-1999 National foreword This Part of BS
7、 6782 has been prepared by Technical Committee STI/3. It is identical with ISO 9020:1994 Binders for paints and varnishes Determination of free-formaldehyde content of amino resins Sodium sulfite titrimetric method incorporating Corrigendum 1:1996, published by the International Organization for Sta
8、ndardization (ISO). It supersedes BS 6782-7:1995 which is withdrawn. In 1998 the European Committee for Standardization (CEN) accepted ISO 9020:1994 as European Standard EN ISO 9020:1998. Cross-references The Technical Committee has reviewed the provisions of ISO 385-1:1984 and ISO 648:1977 to which
9、 normative reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. Related British Standards are BS 846:1985 and BS 1583:1986 respectively. A British Standard does not purport to include all the necessary provisions of a contract. Users of B
10、ritish Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Publication referred toCorresponding British Standard ISO 842:1984BS 4726:1986 Methods for sampling raw materials for paints and varnishes (Id
11、entical) ISO 3696:1987BS EN ISO 3696:1995 Water for analytical laboratory use. Specification and test methods (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN ISO title page, pages 2 to 8, an inside back cover and a back cover. This st
12、andard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 9020 April 1998 ICS 35.100 Descriptors: Paints, varnishes, binders (materials), the
13、rmosetting resins, aminoplasts, chemical analysis, determination of content, formaldehyde, volumetric analysis English version Binders for paints and varnishes Determination of free-formaldehyde content of amino resins Sodium sulfite titrimetric method (ISO 9020:1994, including Technical Corrigendum
14、 1:1996) Liants pour peintures et vernis Dosage du formaldhyde libre dans les rsines aminoplastes Mthode titrimtrique au sulfite de sodium (ISO 9020:1994, Rectificatif technique 1:1996 inclus) Bindemittel fr Beschichtungsstoffe Bestimmung des Gehaltes an freiem Formaldehyd in Aminharzen Titrimetrisc
15、hes Verfahren mit Natriumsulfit (ISO 9020:1994, einschlielich Technische Korrektur 1:1996) This European Standard was approved by CEN on 26 March 1998. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the statu
16、s 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 Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A ve
17、rsion in any other language 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, Fr
18、ance, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels
19、1998 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 9020:1998 E EN ISO 9020:1998 BSI 05-1999 2 Foreword The text of the International Standard from Technical Committee ISO/TC 35, Paints and varnishes, of the International Orga
20、nization for Standardization (ISO) has been taken over as a European Standard by Technical Committee CEN/TC 139, Paints and varnishes, the Secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by en
21、dorsement, at the latest by month of October 1998, and conflicting national standards shall be withdrawn at the latest by October 1998. According to CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Fin
22、land, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of the International Standard ISO 9020:1994, including Technical Corrigendum 1:1996, has been approved by CEN as a Europea
23、n Standard without any modification. NOTENormative references to International Standards are listed in Annex ZA (normative). BS EN ISO 9020:1998 BSI 05-19993 1 Scope This International Standard specifies a titrimetric method for determining the free-formaldehyde content of amino resins. It is applic
24、able to resins resulting from the polycondensation of urea and melamine with formaldehyde and to furan resins resulting from the polycondensation of furfuryl alcohol with formaldehyde without further modification. The method is not applicable to furan resins modified with phenolic resins. 2 Normativ
25、e references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this Internati
26、onal Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 385-1:1984, Laboratory glassware Burettes Part 1: General requirements. ISO 648
27、:1977, Laboratory glassware One-mark pipettes. ISO 842:1984, Raw materials for paints and varnishes Sampling. ISO 3696:1987, Water for analytical laboratory use Specification and test methods. 3 Principle The method is based on the following reactions: Free formaldehyde and alcohol formaldehyde semi
28、acetals in a test portion are reacted with excess sodium sulfite solution at a temperature of 0 C to form hydroxymethane sulfonate. The excess sodium sulfite is titrated with iodine solution. The hydroxymethane sulfonate is decomposed with sodium carbonate solution and the sodium sulfite liberated i
29、s titrated with iodine solution. 4 Reagents and materials During the analysis, use only reagents of recognized analytical grade and only water of at least grade 3 purity as defined in ISO 3696. 4.1 Sodium sulfite solution, c(Na2SO3) = 1 mol/l. 4.2 Acetic acid, c(CH3COOH) = 1 mol/l. 4.3 Sodium carbon
30、ate solution, c(Na2CO3) . 100 g/l. 4.4 Buffer solution. BS EN ISO 9020:1998 4 BSI 05-1999 Dissolve 12,37 g of boric acid in water in a 1 000 ml one-mark volumetric flask, add 100 ml of 1 mol/l sodium hydroxide solution, dilute to the mark with water and mix well. Before use, cool the solution to 0 C
31、. 4.5 Iodine, standard volumetric solution, c(l2) = 0,05 mol/l, i.e. 12,690 g/l. If necessary, standardize the solution against sodium thiosulfate standard reference solution c(Na2S2O3) = 0,1 mol/l. 4.6 Dichloromethane, neutral (pH = 7). Before use, cool the dichloromethane to 0 C. 4.7 Starch, disso
32、lved in hot water to give a 10 g/l solution, or powdered starch, soluble in cold water (so-called Zulkovsky starch is suitable). 4.8 Water containing ice, prepared from water of at least grade 3 purity as defined in ISO 3696. 4.9 Ice, finely divided, prepared from water of at least grade 3 purity as
33、 defined in ISO 3696. 5 Apparatus Ordinary laboratory apparatus and glassware complying with the requirements of ISO 385-1 (burettes) or ISO 648 (pipettes), together with the following: 5.1 High-speed mixer. 5.2 Magnetic stirrer. 5.3 Ice bath. 5.4 Burettes or, preferably, microburettes, of suitable
34、capacity. 5.5 Pipettes, of capacity 10 ml and 25 ml. 6 Sampling Take a representative sample of the product to be tested, as described in ISO 842. 7 Procedure Carry out the determination in duplicate. 7.1 Test portion By reference to Table 1, select the appropriate test-portion mass. If the free-for
35、maldehyde content cannot be predicted, take a test portion of about 1 g and carry out a preliminary determination. Weigh, to the nearest 0,001 g, the test portion into a 600 ml beaker. Table 1 Mass of test portion 7.2 Determination Ensure that the temperature of the contents of the beaker is not hig
36、her than 0 C during the whole determination. If necessary, add some finely divided ice (4.9) to the mixture. In the case of water-soluble products, dissolve the test portion immediately in a mixture of 150 ml of water containing ice (4.8), about 10 g of finely divided ice (4.9) and 25 ml of the buff
37、er solution (4.4). In the case of products that do not form clear solutions with water, dissolve the test portion immediately in 50 ml of dichloromethane (4.6). Then add a mixture of 150 ml of water containing ice (4.8), about 20 g of finely divided ice (4.9) and 25 ml of the buffer solution (4.4) a
38、nd emulsify with the high-speed mixer (5.1) for 10 s. Withdraw the mixer and rinse it with a small volume of water containing ice (4.8) to remove adhering liquid. Collect the rinsings in the test solution. Expected free-formaldehyde content Approximate mass of test portion % (m/m) g up to 0,5 from 0
39、,5 to 1 from 1 to 2 from 2 to 3 from 3 to 5 3,0 1,5 1,0 0,5 0,25 BS EN ISO 9020:1998 BSI 05-19995 Place the beaker in the ice bath (5.3) and stir the contents of the beaker, using the magnetic stirrer (5.2). Whilst continuously stirring, add, by means of a burette (5.4), 2 ml of sodium sulfite solut
40、ion (4.1). Continue stirring for 15 min and add 10 ml of acetic acid (4.2) and either 50 mg of powdered starch or 3 or 4 drops of starch solution (4.7). Titrate with iodine solution (4.5) until a greyish-blue or violet coloration is obtained that is stable for at least 10 s. Then add 30 ml of sodium
41、 carbonate solution (4.3). Titrate the liberated sodium sulfite with iodine solution until a blue coloration is obtained that is stable for at least 1 min. Record the volume V of the iodine solution required for the titration of the liberated sodium sulfite. 8 Expression of results 8.1 Calculation C
42、alculate the free-formaldehyde content w(CH2O, free), expressed as a percentage by mass, using the equation where If the two results (duplicates) differ by more than the value indicated in 8.2.1, repeat the procedure described in clause 7. Calculate the mean of two valid results (replicates) and rep
43、ort the result to the nearest 0,1 % (m/m). 8.2 Precision 8.2.1 Repeatability (r) The value below which the absolute difference between two single test results, each the mean of duplicates, obtained on identical material by one operator in one laboratory within a short interval of time using the stan
44、dardized test method, may be expected to lie with a 95 % probability is 0,06 % (m/m) (absolute) for products having free-formaldehyde contents up to 1 % (m/m); 6 % (relative) for products having free-formaldehyde contents above 1 % (m/m). 8.2.2 Reproducibility (R) The value below which the absolute
45、difference between two single test results, each the mean of duplicates, obtained on identical material by operators in different laboratories using the standardized test method, may be expected to lie with a 95 % probability is 0,1 % (m/m) (absolute) for products having free-formaldehyde contents u
46、p to 1 % (m/m); 10 % (relative) for products having free-formaldehyde contents above 1 % (m/m). Vis the volume, in millilitres, of iodine solution (4.5) used; fis an adjustment factor to take into account any difference in concentration of the iodine solution (4.5) before standardization, c(l2) nomi
47、nal, and after standardization, c(l2) actual: mis the mass, in grams, of the test portion; 1,5is the mass, in milligrams, of formaldehyde corresponding to 1,00 ml of the iodine solution, c(l2) = 0,5 mol/l; 0,1is the conversion factor necessary to convert milligrams to grams and to express w as a per
48、centage. BS EN ISO 9020:1998 6 BSI 05-1999 9 Test report The test report shall contain at least the following information: a) all details necessary to identify the product tested; b) a reference to this International Standard (ISO 9020); c) the result of the test (mean value) as indicated in clause
49、8; d) any deviation from the test method specified; e) the date of the test. BS EN ISO 9020:1998 BSI 05-19997 Annex ZA (normative) Normative references to international publications with their relevent European publications This 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
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