1、BRITISH STANDARD CONFIRMED AUGUST 1991 BS3900-B5: 1986 ISO6713:1984 Acid extraction Methods of test for paints Part B5: Preparation of acid extracts from liquid paints or coating powders ISO title: Paints and varnishes Preparation of acid extracts from paints in liquid or powder form It is recommend
2、ed that this Part be read in conjunction with the general information in the Introduction to BS3900, issued separately UDC 667.61:620.1BS3900-B5:1986 This British Standard, having been prepared under the directionof the Pigments, Paintsand Varnishes StandardsCommittee, was published under the author
3、ity ofthe Board of BSI and comes intoeffect on 31January1986 BSI 03-1999 The Committees responsible for this British Standard are shown inBS3900: Introduction The following BSI references relateto the work on this standard: Committee reference PVC/10 Draft for comment82/52822 DC ISBN 0 580 14944 7 A
4、mendments issued since publication Amd. No. Date of issue CommentsBS3900-B5:1986 BSI 03-1999 i Contents Page National foreword ii 0 Introduction 1 1 Scope and field of application 1 2 References 1 3 Definitions 1 4 Principle 1 5 Sampling 1 6 Separation of the pigment from the liquid paint sample 1 7
5、 Treatment of paints in powder form 3 8 Acid extraction of the separated pigment and of paints in powder form 3 9 Treatment of the extracted liquied portion 6 Table 4 Publications referred to Inside back coverBS3900-B5:1986 ii BSI 03-1999 National foreword This Part of BS3900 has been prepared under
6、 the direction of the Pigments, Paints and Varnishes Standards Committee. It is identical with ISO6713:1984 “Paints and varnishes Preparation of acid extracts from paints in liquid or powder form” published by the International Organization for Standardization (ISO). It is assumed in the drafting of
7、 this standard that it will be used and applied by those who are appropriately qualified and experienced. The procedures described in this standard are intended to be carried out by suitably trained and/or supervised personnel. The substances and procedures described may be injurious to health if in
8、adequate precautions are taken. This standard refers only to its technical suitability and does not absolve the user from statutory obligations relating to health and safety. Terminology and conventions. The text of the international standard has been approved as suitable for publication as a Britis
9、h Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards, it is current practice to use a full point on the baseline
10、 as the decimal marker. In British Standards it is current practice to use the symbol “L” for litre rather than “l”, and to use the spelling “sulphur”, etc.,instead of “sulfur”, etc. Wherever the words “International Standard” appear, referring to this standard, they should be read as “British Stand
11、ard”. Cross-references ISO3856, to which general reference is made, is published in a number of Parts of BS3900. At the time of publication of this standard, the relationship between other Parts of BS3900 and Parts of ISO3856 was as follows: International standards Corresponding British Standards IS
12、O1042:1983 BS1792:1982 Specification for one-mark volumetric flasks (Identical) BS3900 Methods of test for paints ISO1512:1974 Part A1:1970 Sampling (Technically equivalent) ISO1513:1980 Part A2:1983 Examination and preparation of samples for testing (Identical) Part of ISO3856 Corresponding Part of
13、 BS3900 BS3900 Methods of test for paints ISO3856/1:1984 a b Part B6:1986 Determination of “soluble” lead content (Identical) ISO3856/2:1984 Part B7:1986 Determination of “soluble” antimony content (Identical) ISO3856/3:1984 Part B8:1986 Determination of “soluble” barium content (Identical) ISO3856/
14、4:1984 Part B9:1986 Determination of “soluble” cadmium content (Identical) ISO3856/5:1984 Part B10:1986 Determination of hexavalent chromium content of solid matter (Identical) ISO3856/6:1984 Part B11:1986 Determination of total chromium content of liquid matter (Identical)BS3900-B5:1986 BSI 03-1999
15、 iii Both ISO3696 and ISO6714 are in course of preparation. The Technical Committee has reviewed the proposed provisions of ISO3696, to which reference is made in8.2.1, and has decided that they are acceptable for use in conjunction with this standard. ISO3696 is related to BS3978 “Water for laborat
16、ory use”. The reference to ISO6714 in clause1 is for information only and, therefore, does not affect the validity of this standard. Additional information. In the note to8.3.1, reference is made to “mass of lead-containing sample”. As this clause refers to the treatment of the pigment separated fro
17、m the original sample, this text should read “mass of lead-containing pigment in the paint sample”. To align the treatment of the blank solution with the procedure given in8.2.3 (line7 and8) and8.3.2.4 (lines7 and8), the text in8.4 (lines2 and3) should read “., add2ml of the ethanol(8.2.1.3) or the
18、minimum larger quantity required to wet the test portion (see8.2.3 and8.3.2.4)”. 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
19、confer immunity from legal obligations. ISO3856/7:1984 Part B12:1986 Determination of “soluble” mercury content (Identical) a Specific reference to ISO3856/1 is made in8.3.2.4. b Attention is drawn to a similar standard, BS3900-B3 “Determination of “soluble” lead in the solid matter in liquid paints
20、: method for use in conjunction with The Control of Lead at Work Regulations,1980 (S.I.1980 No.1248)”. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages1to6, an inside back cover and a back cover. This standard has been updated (see copyright date) a
21、nd may have had amendments incorporated. This will be indicated in the amendment table on theinside front cover.iv blankBS3900-B5:1986 BSI 03-1999 1 0 Introduction This International Standard is for use in conjunction with the appropriate parts of ISO3856. 1 Scope and field of application This Inter
22、national Standard describes methods for the preparation of acid extracts required as the test solutions for the determination of the “soluble” metal contents of paints and related products in liquid or powder form. The acid extracts are prepared in0,07mol/l hydrochloric acid, which is chosen as an a
23、pproximation of the acid in the stomach. This International Standard is not applicable to dried or comminuted paint films (see ISO6714). WARNING The procedures described in this International Standard are intricate and, therefore, should be carried out by those who are properly experienced in these
24、analytical procedures. Adequate precision will only be obtained if all the details of the separation and extraction procedures are strictly observed. 2 References ISO1042, Laboratory glassware One-mark volumetric flasks. ISO1512, Paints and varnishes Sampling. ISO1513, Paints and varnishes Examinati
25、on and preparation of samples for testing. ISO3696, Water for laboratory use Specifications 1) . ISO3856, Paints and varnishes Determination of “soluble” metal content. ISO6714, Paints and varnishes Preparation of acid extracts from dried films 1) . 3 Definitions For the purpose of this Internationa
26、l Standard the following definitions apply. 3.1 pigment all particulate matter insoluble in the selected extracting solvent(6.2) 3.2 “soluble” metal content of liquid paint the metal content of the pigment that is soluble in a defined dilute acid plus the total metal content present in the liquid po
27、rtion of the paint NOTEThe defined dilute acid for the purpose of this International Standard is0,07mol/l hydrochloric acid. 3.3 “soluble” metal content of paint in powder form the metal content of the paint that is soluble in a defined dilute acid (see note to3.2) 4 Principle 4.1 Dilution of a samp
28、le of the liquid product to be tested with a suitable solvent, followed by centrifugal separation of the pigment in the sample. Three methods, dependent on the binder of the product being examined, are described for the separation of the pigment (see6.4). 4.2 Extraction with0,07mol/l hydrochloric ac
29、id of the separated pigment at a mass : volume ratio between the pigment and the hydrochloric acid of1:15, as described in8.2, except for the determination of “soluble” lead when the total lead content of the paint (see8.3.1.5) equals or exceeds1% (m/m). In that case, extraction of the separated pig
30、ment at a mass : volume ratio between the lead-containing pigment in the sample and the hydrochloric acid of1:1 000, as described in8.3. NOTE For the purpose of this International Standard, it has been assumed that the lead content of a lead-containing pigment is60 % (m/m). This corresponds to the c
31、ontent found in most lead chromes (see8.3.2.1). 4.3 Evaporation to dryness of the liquid portion of the product obtained by centrifuging(4.1). Preparation of the residue for analysis by dry ashing and extraction of the ash with nitric acid. 4.4 For paints in powder form, extraction of the product to
32、 be tested as in4.2, without prior separation of the binder (see clause7). 5 Sampling Take a representative sample of the product to be tested as described in ISO1512. 6 Separation of the pigment from the liquid paint sample 6.1 Preparation of the test sample Examine and prepare the sample for testi
33、ng as described in ISO1513. If any skin is present, remove it as far as possible. Thoroughly stir the sample and, if necessary, pass it through a sieve of nominal aperture1504m to remove any remaining skin and other extraneous matter. 1) At present at the stage of draft.BS3900-B5:1986 2 BSI 03-1999
34、6.2 Reagents WARNING In selecting the solvent to be used, possible toxic and other hazards and necessary precautions should be taken into consideration. Select a solvent that effects the optimum separation of the pigment. The solvent selected shall be recorded and subsequently reported as required i
35、n ISO3856. Examples of suitable solvents or solvent mixtures are as follows : a) for solvent-thinned paints, printing inks and similar products (method A): Toluene/ethanol (4 + 1) (for air drying paints) Xylene/butan-1-ol (9 + 1) (for stoving paints) Toluene (for chlorinated rubber paints) Butanone
36、methyl ethyl ketone, MEK (for products containing cellulose nitrate) b) for emulsion paints based on aqueous polymer dispersions (method B): Acetone 1,1,1-Trichloroethane Tetrahydrofuran c) for plastisols and organosols based on polyvinyl chloride (PVC) and its copolymers and for paints based on oth
37、er non-aqueous polymer dispersions (method C): Tetrahydrofuran Cyclohexanone Cyclopentanone 6.3 Apparatus Ordinary laboratory apparatus and glassware, and in particular: 6.3.1 Suitable laboratory centrifuge, with tubes of inert material of capacity50or100ml. A centrifuge, capable of imparting a rela
38、tive centrifugal acceleration of100km/s 2 , is preferred. 6.3.2 Air-ventilated oven, capable of being maintained at105 2 C. 6.3.3 Stoppered glass container, of at least2lcapacity. 6.4 Procedure 6.4.1 Method A (for solvent-thinned paints, printing inks and similar products) Weigh, to the nearest10mg,
39、 a number (see note1) of centrifuge tubes(6.3.1). Add10 to20g (seenote2) of the prepared sample (6.1) to each tube, taking care to avoid contamination of the walls and lip of the tube. Immediately weigh the tubes and contents to the nearest10mg. Approximately half fill the tubes with the selected so
40、lvent(6.2) and stir thoroughly using a glass rod. Wash each glass rod thoroughly with the solvent, adding all washings to the appropriate tube. Balance the opposing centrifuge tubes to within0,1g by adding further solvent, taking care to ensure that an adequate working level is not exceeded. Centrif
41、uge until there is a complete separation into a liquor and a pigment cake. Decant the supernatant liquor from all the tubes comprising a “set” (see note1) into the container(6.3.3). Add further solvent to each tube and mix thoroughly as specified above, taking care to disperse the pigment cake compl
42、etely. Repeat the centrifuging and transfer the liquor to the same container. Repeat the addition of solvent, centrifuging and transfer of liquor for further three times, taking special care, as before, to thoroughly disperse the pigment cake. As a final treatment for the pigment cake and to assist
43、rapid drying, use acetone in place of the selected solvent. Add the acetone and mix, taking special care to disperse the whole pigment cake. Centrifuge and transfer the liquor as before to the container. Retain the container with the combined extracts for the procedure described in clause9. After en
44、suring that excess acetone has evaporated, place the centrifuge tubes in the oven(6.3.2), maintained at105 2 C, for a minimum period of3h. Remove, transfer to a desiccator, allow to cool to ambient temperature and weigh each tube and contents to the nearest10mg. Return the tubes and contents to the
45、oven for a minimum period of1h, allow to cool to ambient temperature in the desiccator and reweigh. Repeat the heating, cooling and weighing operations until the results of two consecutive weighings do not differ by more than10mg. Calculate the pigment content of the paint as a percentage by mass of
46、 the paint sample. At the end of the separation procedure, check that the dried pigment cake can be crumbled easily to indicate that the binder has been satisfactorily extracted. If the cake remains cohesive, repeat the whole procedure on the original paint using a more suitable solvent or solvent m
47、ixture. NOTE 1Subsequent acid extractions should be carried out in duplicate and therefore sufficient paint and tubes should be taken so that at least10g of pigment is obtained. The number of tubes (usually four) required for each sample is referred to as a“set”.BS3900-B5:1986 BSI 03-1999 3 NOTE 2Th
48、e mass of paint taken is dependent upon the capacity of the centrifuge tubes employed and on the expected pigment content of the paint. 6.4.2 Method B (for emulsion paints based on aqueous polymer dispersions) Carry out the separation as described in6.4.1, but use acetone for the first and the final
49、 treatments and the selected solvent for the five intermediate treatments of the pigment cake. 6.4.3 Method C for plastisols and organosols based on polyvinyl chloride (PVC) and its copolymers and for paints based on other non-aqueous polymer dispersions. Carry out the separation as described in6.4.1, but using a mass of sample such that it may be diluted with solvent in the ratio of1:10. This ratio is necessary to obtain a practical sedimentation rate. Stir very thoroughly for sufficient time to convert the polymer from the dispersed to the dis
