1、BRITISH STANDARD BS318:1988 ISO4621:1986 Specification for Chrome oxide green pigments for paints ISO title: Chrome oxide green pigments Specifications and methods of test UDC 661.875.2213:627.027.524.11:620.1BS318:1988 This British Standard, having been prepared under the directionof the Pigments,
2、Paintsand Varnishes StandardsCommittee, was published under the authority ofthe Board of BSI and comes intoeffect on 29 January1988 BSI 08-1999 First published April1928 First revision August1938 Second revision April1952 Third revision April1968 Fourth revision January1988 The following BSI referen
3、ces relate to the work on this standard: Committee reference PVC/1 Draft for comment80/50243 DC ISBN 0 580 16366 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Pigments, Paints and Varnishes Standards Committee(PVC/-) to Technical Com
4、mittee PVC/1 upon which the following bodies were represented: Aluminium Powder and Paste Association British Colour Makers Association British Precast Concrete Federation Ltd. Cement Makers Federation Chemical Industries Association Oil and Colour Chemists Association Paintmakers Association of Gre
5、at Britain Ltd. Red Lead and Litharge Manufacturers Association Titanium Pigment Manufacturers Technical Committee Amendments issued since publication Amd. No. Date of issue CommentsBS318:1988 BSI 08-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope and fiel
6、d of application 1 2 References 1 3 Definition 1 4 Classification 1 5 Required characteristics and their tolerances 1 6 Sampling 1 7 Determination of total chromium content as chromium(III) oxide 1 8 Determination of “soluble” chromium content 3 9 Determination of loss on ignition at1000 C 5 10 Resi
7、stance to acid and alkali 5 11 Test report 5 Table 1 Essential requirements 2 Table 2 Conditional requirements 2 Table 3 Standard colorimetric solutions 4 Publications referred to Inside back coverBS318:1988 ii BSI 08-1999 National foreword This British Standard has been prepared under the direction
8、 of the Pigments, Paints and Varnishes Standards Committee. It is identical with ISO4621:1986“Chrome oxide green pigments Specifications and methods of test”, published by the International Organization for Standardization(ISO). This revision supersedes BS318:1968, which is withdrawn. BS318 was firs
9、t published in1928 and this fourth revision brings the standard into line with international agreements by implementing the International Standard as an identical British Standard. The main differences from the1968 edition of this British Standard are as follows: a) the requirements for a type suita
10、ble for rubbers and plastics are omitted; b) the grades are differentiated by particle size requirements specified with reference to a454m sieve; c) the sampling is carried out according to the standardized procedure for raw materials for paints; d) oil absorption, colour, relative tinting strength
11、and dispersibility are included in conditional requirements. It has been assumed in the drafting of this standard that it will be used and applied by those who are appropriately qualified and experienced. Terminology and conventions. The text of the International Standard has been approved as suitab
12、le for publication as a British 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
13、 a full point on the baseline as the decimal marker. The symbol “l” has been used to denote litre(and in its submultiples). In British Standards it is current practice to use the symbol “L” and to use the spelling “sulphur”, etc., instead of “sulfur”, etc. Wherever the words “International Standard”
14、 appear, referring to this standard, they should be read as “British Standard” and “ISO4621” should be read as “BS318”. Cross-references International Standard Corresponding British Standard BS3483 Methods for testing pigments for paints ISO787-1:1982 Part A1:1983 Comparison of colour (Identical) IS
15、O787-2:1981 Part B6:1982 Determination of matter volatile at105 C (Identical) ISO787-3:1979 Part C1:1980 Determination of matter soluble in water(hot extraction method) (Identical) ISO787-5:1980 Part B7:1982 Determination of oil absorption value (Identical) ISO787-7:1981 Part B3:1982 Determination o
16、f residue on sieve (watermethod, using manual procedure) (Identical) ISO787-9:1981 Part C4:1982 Determination of pH value of an aqueous suspension (Identical)BS318:1988 BSI 08-1999 iii The Technical Committee has reviewed the provisions of ISO385-1:1984 and ISO648:1977, to which reference is made in
17、 the text, and has decided that they are acceptable for use in conjunction with this standard. Related British Standards for these International Standards are BS846:1985 “Specification for burettes” and BS1583:1986 “Specification for one-mark pipettes” respectively. Additional information. In order
18、to carry out some of the tests described in this standard it is necessary for a reference sample to be supplied or agreed by the parties concerned(see Table 2). A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for t
19、heir correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. International Standard Corresponding British Standard ISO787-16:1986 Part A4:1988 Determination of relative tinting strength and colour on reduction of coloured pigments using visu
20、al comparison a(Identical) ISO787-20:1975 Part B5:1974 Comparison of ease of dispersion (oscillatory shaking method) (Technically equivalent) ISO842:1984 BS4726:1986 Methods for sampling raw materials for paints and varnishes (Identical) ISO1042:1983 BS1792:1982 Specification for one-mark volumetric
21、 flasks (Technically equivalent) ISO3696:1987 b BS3978:1987 Specification for water for laboratory use (Identical) BS3900 Methods of test for paints ISO3856-6:1984 Part B11:1986 Determination of total chromium content of liquid matter (Identical) ISO6713:1984 Part B5:1986 Preparation of acid extract
22、s from liquid paints or coating powders (Identical) a In preparation. b Since ISO3696 has been published the footnote to clause2 of BS318 is no longer valid. Summary of pages This document comprises a front cover, an inside front cover, pagesi toiv, pages1to6, an inside back cover and a back cover.
23、This standard 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.iv blankBS318:1988 BSI 08-1999 1 1 Scope and field of application This International Standard specifies the requirements and correspon
24、ding methods of test for chrome oxide green pigments suitable for general use. 2 References ISO385-1, Laboratory glassware Burettes Part1: General requirements. ISO648, Laboratory glassware One-mark pipettes. ISO787, General methods of test for pigments and extenders Part1: Comparison of colour of p
25、igments Part2: Determination of matter volatile at105 C Part3: Determination of matter soluble in water Hot extraction method Part5:Determination of oil absorption value Part7: Determination of residue on sieve Watermethod Manual procedure Part9:Determination of pH value of an aqueous suspension Par
26、t16: Determination of relative tinting strength(or equivalent colouring value) and colour on reduction of coloured pigments Visual comparison method Part20: Comparison of ease of dispersion(Oscillatory shaking method). ISO842, Raw materials for paints and varnishes Sampling. ISO1042, Laboratory glas
27、sware One-mark volumetric flasks. ISO3696, Water for laboratory use Specifications 1) . ISO3856-6, Paints and varnishes Determination of “soluble” metal content Part6: Determination of total chromium content of the liquid portion of the paint Flame atomic absorption spectrometric method. ISO6713, Pa
28、ints and varnishes Preparation of acid extracts from paints in liquid or powder form. 3 Definition chrome oxide green pigment an inorganic, coloured pigment consisting essentially of chromium(III) oxide(Cr 2 O 3 ) in the form of a dry powder 4 Classification This International Standard specifies the
29、 following three grades of chrome oxide green pigments, which shall not be in admixture with other colouring matter of organic or inorganic nature and shall be free from extenders or diluents (seealso the note to clause9). Grade1: These pigments shall contain a residue on a sieve of454m mesh apertur
30、e of not more than0,01%(m/m). Grade2: These pigments shall contain a residue on a sieve of454m mesh aperture of more than0,01%(m/m) and not more than0,1%(m/m). Grade3: These pigments shall contain a residue on a sieve of454m mesh aperture of more than0,1%(m/m) and not more than0,5%(m/m). 5 Required
31、characteristics and their tolerances 5.1 For chrome oxide green pigments complying with this International Standard, the essential requirements are specified in Table 1 and the conditional requirements are referred to in Table 2. For the conditional requirements according to Table 2, agreement betwe
32、en the interested parties is necessary. 5.2 The agreed reference pigment, referred to in Table 2, shall conform with the requirements specified in Table 1. 6 Sampling Take a representative sample of the product to be tested as described in ISO842. 7 Determination of total chromium content as chromiu
33、m(III) oxide 7.1 Reagents During the analysis, use only reagents of recognized analytical grade and only water of at least grade3 purity according to ISO3696. WARNING Use the reagents in accordance with the appropriate health and safety regulations. 7.1.1 Sodium peroxide 7.1.2 Sulfuric acid, 1+1. Ca
34、utiously add1 volume of sulfuric acid,96%(m/m), to1 volume of water, while cooling. 1) At present at the stage of draft.BS318:1988 2 BSI 08-1999 Table 1 Essential requirements Table 2 Conditional requirements 7.1.3 Ammonium iron(II) sulfate, standard volumetric solution, c(NH 4 ) 2 Fe(SO 4 ) 2 6H 2
35、O. 0,2mol/l. 7.1.3.1 Preparation Dissolve78,4g of ammonium iron(II) sulfate hexahydrate in about200ml of water and add50ml of the sulfuric acid(7.1.2). Dilute to the mark in a1000ml one-mark volumetric flask, complying with the requirements of ISO1042, and mix well. 7.1.3.2 Standardization Immediate
36、ly before use standardize the ammonium iron(II) sulfate solution(7.1.3.1) by the following procedure. Weigh, to the nearest0,1mg, approximately0,9g of the potassium dichromate(7.1.4), dissolve it in200ml of water and acidify with10ml of the sulfuric acid solution(7.1.2). Titrate the solution as desc
37、ribed in7.3.2. 7.1.4 Potassium dichromate, dried at150 to200 C. 7.1.5 Ammonium persulfate 7.1.6 Silver nitrate 7.2 Apparatus Ordinary laboratory apparatus, and 7.2.1 Crucible, made of alumina or other suitable material such as zirconium, fitted with a lid. 7.2.2 Muffle furnace, capable of being main
38、tained at700 25 C. 7.2.3 Burette, of capacity100ml, complying with the requirements of ISO385-1. 7.2.4 pH meter, with a range of0 to1400mV. 7.2.5 Calomel electrode 7.2.6 Platinum electrode 7.2.7 Magnetic stirrer, with a polytetrafluoroethylene (PTFE) coated rod. 7.3 Procedure Carry out the determina
39、tion, together with the blank determination, in duplicate. 7.3.1 Test portion Weigh, to the nearest0,1mg, a test portion of approximately0,5g into the crucible(7.2.1), add5 to6g of the sodium peroxide(7.1.1), and mix well. Characteristic Requirement Test method Chromium content, expressed as Cr 2 O
40、3 %(m/m) min.96 Clause7 “Soluble” chromium content %(m/m) max.0,02 Clause8 Matter volatile at105 C %(m/m) max.0,3 ISO787-2 Loss on ignition at1000 C %(m/m) max.1 Clause9 Matter soluble in water(hot extraction method) %(m/m) max.0,2 ISO787-3 Residue on sieve(454m) grade1 %(m/m) max.0,01 ISO787-7 a gr
41、ade2 %(m/m) Greater than0,01, max.0,1 grade3 %(m/m) Greater than0,1, max.0,5 a It will be necessary to break up loose agglomerates on the sieve by gently brushing, but care should be taken not to disrupt aggregates. Characteristic Requirement Test method Colour Shall closely match that of the agreed
42、 reference pigment(5.2) ISO787-1 Relative tinting strengh Shall closely match that of the agreed reference pigment(5.2) ISO787-16 Ease of dispersion Shall not be inferior to that of the agreed reference pigment(5.2) ISO787-20, or other agreed method pH of aqueous suspension Shall not differ by more
43、than1pH unit from that of the agreed reference pigment(5.2) ISO787-9 Oil absorption value Shall not differ by more than15% from the value agreed between the interested parties ISO787-5 Resistance to acid and alkali The colour change shall not be greater than that of the agreed reference pigment(5.2)
44、. Clause10BS318:1988 BSI 08-1999 3 7.3.2 Determination Cover the crucible and heat in the muffle furnace(7.2.2), maintained at700 25 C, for10min. Allow the crucible and lid to cool for10min and then immerse them in about200ml of water in a600ml beaker and immediately cover the beaker with a watch-gl
45、ass. Gently warm the beaker and contents until the vigorous reaction ceases. Carefully remove the crucible and lid and rinse them with water until free from the solution. Return the rinsings to the beaker. Cool, add sufficient sulfuric acid(7.1.2) to change the colour from yellow to orange, and then
46、 add a further10ml of the sulfuric acid(7.1.2). Add2,5g of the ammonium persulfate(7.1.5) and0,01g of the silver nitrate(7.1.6), and gently boil for30min. Cool, stir the solution by means of the magnetic stirrer(7.2.7) and titrate it potentiometrically by adding the ammonium iron(II) solution(7.1.3)
47、 from the burette(7.2.3), using the pH meter(7.2.4) and electrodes(7.2.5 and7.2.6) to determine the end-point. NOTEThe end-point of the titration may also be determined by addition of a redox indicator, for example sodium diphenylamine sulfonate. In this case,15ml of orthophosphoric acid88%(m/m) and
48、 an additional20ml portion of the sulfuric acid(7.1.2) should be added to the solution before titration. The indicator should be added shortly before the end-point is reached. 7.4 Expression of results 7.4.1 Calculation Calculate the total chromium content of the pigment, using the equation where Ta
49、ke the mean of the two determinations, but if the duplicate determinations differ by more than0,2%(m/m), repeat the procedure. 7.4.2 Precision No precision data are currently available. 8 Determination of “soluble” chromium content 8.1 Preparation of the hydrochloric acid extract Prepare the hydrochloric acid extract of the pigment sample by the method described in ISO6713, sub-clause8.2. 8.2 Determination of chromium NOTEFor the determination of acid-soluble chromium, two methods are provided. Me
