1、BRITISH STANDARD BS4313:1988 ISO2040:1972 Specification for Strontium chromate pigments for paints ISO title: Strontium chromate pigments for paints UDC 667.662:661.843:661.875.27:620.1.113BS4313:1988 This BritishStandard, having been prepared under the directionof the Pigments, Paintsand Varnishes
2、StandardsCommittee, was published under the authorityofthe Board of BSI andcomes into effect on 30November1988 BSI12-1999 First published April1968 First revision The following BSI references relate to the work on this standard: Committee reference PVC/1 Draft for comment76/50335 DC ISBN 0 580 16979
3、 0 Committees responsible for this BritishStandard The preparation of this BritishStandard was entrusted by the Pigments, Paints and Varnishes Standards Committee (PVC/-) to Technical Committee PVC/1 upon which the following bodies were represented: Aluminium Powder and Paste Association British Col
4、our Makers Association British Precast Concrete Federation Ltd. Cement Makers Federation Chemical Industries Association Oil and Colour Chemists Association Paintmakers Association of Great Britain Ltd. Red Lead and Litharge Manufacturers Association Titanium Pigment Manufacturers Technical Committe
5、e Amendments issued since publication Amd. No. Date of issue CommentsBS4313:1988 BSI 12-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope and field of application 1 2 References 1 3 Required characteristics and their tolerances 1 4 Sampling 1 5 Methods of te
6、st 1 Table Required characteristics and their tolerances 2 Publications referred to Inside back coverBS4313:1988 ii BSI 12-1999 National foreword This BritishStandard has been prepared under the direction of the Pigments, Paints and Varnishes Standards Committee. It is identical with ISO2040:1972 “S
7、trontium chromate pigments for paints” published by the International Organization for Standardization (ISO) and confirmed in1985. This revision supersedes BS4313:1968 which is withdrawn. BS4313 was first published in1968 and this first revision brings the standard in line with international agreeme
8、nts by implementing the International Standard as an identical BritishStandard. The main differences from the1968 edition of this BritishStandard are as follows: a) the requirement for total chromate content has been reduced; b) the requirement for soluble chromate content has been reduced; c) the s
9、ieve residue is carried out only by the water method. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a BritishStandard without deviation. Some terminology and certain conventions are not identical with those used in BritishStandar
10、ds; attention is drawn especially to the following. The comma has been used as a decimal marker. In BritishStandards it is current practice to use a full point on the baseline as the decimal marker. The symbol “l” has been used to denote litre (and in its submultiples). In BritishStandards it is cur
11、rent practice to use the symbol “L”. Wherever the words “International Standard” appear, referring to this standard, they should be read as “BritishStandard”. The Technical Committee has reviewed the provisions of ISO/R787-X 1) , to which reference is made in the text, and has decided that they are
12、acceptable for use in conjunction with this standard. A related BritishStandard to ISO787-10 is BS3483 “Methods for testing pigments for paints” Part B8:1982 “Determination of density (pyknometer method)”. Since the publication of ISO2040, ISO787-VI has been withdrawn and the Technical Committee has
13、 reviewed the position and decided that for the purposes of this standard it is acceptable that only the sieve analysis by the water method given in ISO/R787-VII 2)should apply. Cross-references International Standard Corresponding BritishStandard BS3483 Methods for testing pigments for paints ISO78
14、7-2:1981 a Part B6:1982 Determination of matter volatile at105 C (Identical) ISO787-5:1980 b Part B7:1982 Determination of oil absorption value (Identical) ISO787-7:1981 c Part B3:1982 Determination of residue on sieve (water method, using a manual procedure) (Identical) ISO842:1984 d BS4726:1986 Me
15、thods for sampling raw materials for paints and varnishes (Identical) a Referred to in the text as ISO/R787-II. b Referred to in the text as ISO/R787-V. c Referred to in the text as ISO/R787-VII. d Referred to in the text as ISO/R842. 1) Now published as ISO787-10:1981. 2) Now published as ISO787-7:
16、1981BS4313:1988 BSI 12-1999 iii Additional information. In clause5, water complying with grade3 of BS3978 is suitable. For the hydrochloric acid solution specified in5.1.1 and5.3.3.1, and the sulphuric acid specified in5.3.4.2, the density unit is grams per millilitre. The concentrations of a number
17、 of volumetric solutions are given as obsolete normalities and molarities. The concentrations in SIunits are as follows. 0.1N Sodium thiosulphate: c(Na 2 S 2 O 3 )=0.1mol/L 2N Hydrochloric acid: c(HCl)=2mol/L 1M Potassium iodide: c(KI)=1mol/L 0.1N Silver nitrate: c(AgNO 3 )=0.1mol/L 5N Sulphuric aci
18、d: c(H 2 SO 4 )=2.5mol/L 4N Sodium hydroxide: c(NaOH)=4mol/L. 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 confer immunity fro
19、m legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi to iv, pages1to4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment ta
20、ble on the inside front cover.iv blankBS4313:1988 BSI 12-1999 1 1 Scope and field of application This International Standard lays down the requirements and test methods for strontium chromate pigments of approximate composition SrCrO 4suitable for use in paints and corrosion-inhibiting coatings. 2 R
21、eferences ISO/R787, General methods of test for pigments. ISO/R842, Sampling raw materials for paints and varnishes. 3 Required characteristics and their tolerances Strontium chromate pigments for paints shall have the characteristics shown in the Table below. 4 Sampling A representative sample of t
22、he pigment shall be taken in accordance with ISO/R842. 5 Methods of test All reagents used shall be of recognized analytical reagent quality. Distilled water or water of at least equivalent purity shall be used. 5.1 Determination of strontium content 5.1.1 Reagents 1) Acetic acid,10%(V/V) solution.
23、2) Hydrochloric acid, d =1.18. 3) Sulphuric acid,50g/l solution. 4) Sulphamic acid 5) Ethanol,95%(V/V). 5.1.2 Apparatus Sintered silica crucible, porosity P16 (maximum pore size10 to16m). 5.1.3 Procedure 5.1.3.1 Test portion Weigh, to the nearest0.1mg, about0.25g of the sample. 5.1.3.2 Determination
24、 Transfer the test portion into a500ml glass-stoppered flask. Add50ml of acetic acid1) and shake or stir for1h at room temperature in such a manner that the pigment is kept in continuous suspension without increasing the temperature of the extracting liquid. Filter the solution through an ash-free c
25、lose-textured filter paper until a perfectly clear filtrate is obtained. Wash the residue on the filter with two12.5ml portions of acetic acid1), combining the filtrate and washings. Add2.5ml of hydrochloric acid2) and70ml of ethanol5) and boil until the volume is reduced to about35ml. Add10ml of et
26、hanol5) and1.5g of sulphamic acid4) and heat the solution to near boiling. Allow to stand on a hot-water bath for1h with occasional stirring. Allow the precipitate so formed to settle at room temperature. When the supernatant liquid is clear and the contents of the beaker cool, filter through the ta
27、red sintered silica crucible (5.1.2). Wash the precipitate with a mixture of9parts of ethanol5) and1part of sulphuric acid solution3) until the filtrate is colourless. Ignite the crucible at800 C for30min, cool in a desiccator and weigh. 5.1.4 Expression of results Calculate the strontium content as
28、 a percentage by mass, expressed as SrO, by the formula where m 0 is the mass, in grams, of the test portion; m 1 is the mass, in grams, of residue. Report the result to one decimal place. 5.2 Determination of total chromate content 5.2.1 Reagents 1) Sodium thiosulphate,0.1N standard volumetric solu
29、tion. 2) Starch solution,1%(m/m). 3) Hydrochloric acid,2N. 4) Potassium iodide,1M solution. 5) Sodium hydrogen carbonate 5.2.2 Procedure 5.2.2.1 Test portion Weigh, to the nearest0.1mg, about0.25g of the sample. 56.416m 1 m 0 -BS4313:1988 2 BSI 12-1999 Table Required characteristics and their tolera
30、nces 5.2.2.2 Determination Dissolve the test portion in30ml of hydrochloric acid3), in a conical stoppered flask. Make up to100ml with water, and add2g of sodium hydrogen carbonate5). Add10ml of potassium iodide solution4) and allow the flask to stand for5min in the dark. Afterwards, titrate with so
31、dium thiosulphate solution1). Towards the end of the titration add5ml of starch solution2) as indicator and titrate until the colour changes to green or blue-green. 5.2.3 Expression of results Calculate the total chromate content as a percentage by mass, expressed as CrO 3 , by the formula where V i
32、s the volume, in millilitres, of0.1 N sodium thiosulphate solution required; T is the normality of the sodium thiosulphate solution; m is the mass, in grams, of the test portion. Report the result to one decimal place. 5.3 Determination of water-soluble chloride and nitrate contents, and water-solub
33、le chromate content The aqueous extract prepared according to5.3.1 is used for the determination of a) water-soluble chloride and nitrate contents; b) water-soluble chromate content. For the water-soluble nitrate content, two methods are provided: Method A (5.3.3) for use when it is only required to
34、 determine whether the content is above or below the specified limit of0.1%; Method B (5.3.4) for use when a precise determination of the content is required. 5.3.1 Preparation of aqueous extract 5.3.1.1 Apparatus Mechanical agitator or stirrer. 5.3.1.2 Procedure 5.3.1.2.1 Test portion Weigh30 0.1g
35、of the sample in a chemically resistant glass flask. 5.3.1.2.2 Preparation Agitate the test portion with300ml of water for1h at room temperature in such a manner that the pigment is kept in continuous suspension without increasing the temperature of the water. Filter the mixture and reserve the perf
36、ectly clear filtrate for the determinations according to5.3.2 to5.3.5. 5.3.2 Determination of water-soluble chloride content 5.3.2.1 Reagents 1) Potassium chromate,50g/l solution. 2) Silver nitrate,0.1 N standard volumetric solution. 5.3.2.2 Procedure Take100ml of the clear aqueous extract(5.3.1) an
37、d add1ml of potassium chromate solution1). Titrate the solution with silver nitrate solution2), slowly and with vigorous shaking, until a faint reddish brown colour persists. Characteristic a Requirement Test method Strontium content % SrO min.48 clause5.1 Total chromate content % CrO 3 min.46 claus
38、e5.2 Water-soluble chloride content % Cl max.0.1 clause5.3.2 Water-soluble nitrate content % NO 3 max.0.1 clause5.3.3 or5.3.4 Chromate content in100ml of extract from10g of pigment g CrO 3 /100ml 0.04 to0.1 clause5.3.5 Volatile matter at105 C % max1.0 ISO/R787-II Oil absorption value, compared with
39、value agreed between the interested parties within 15% ISO/R787-V Residue on sieve (63m) oil method% max.0.5 ISO/R787-VI water method% max.0.3 ISO/R787-VII a If a value for density is agreed between the interested parties, the method for determination shall be that given in ISO/R787-X. 3.33V T m -BS
40、4313:1988 BSI 12-1999 3 Carry out a blank determination by adding1ml of potassium chromate solution1) to100ml of water and titrating with silver nitrate solution2) until the colour matches that of the previous titration, making due allowance for any opalescence or turbidity. NOTEAlternatively, the e
41、nd point of the titration may be determined by potentiometric indication. 5.3.2.3 Expression of results Calculate the water-soluble chloride content as a percentage by mass, expressed as Cl, by the formula 0.0354 (V 1 V 0 ) where V o is the volume, in millilitres, of0.1 N silver nitrate solution req
42、uired in the blank determination; V 1 is the volume, in millilitres, of0.1 N silver nitrate solution required by the test portion. Report the result to two decimal places. 5.3.3 Determination of water-soluble nitrate content Method A 5.3.3.1 Reagents 1) Hydrochloric acid, d =1.18. 2) Sodium hydroxid
43、e solution,200g/l. 3) Ammonium chloride solution,17.2mg/l. 4) Devardas alloy, powdered. 5) Ammonia-free water NOTEAmmonia-free water may be prepared by redistilling approximately500ml of distilled water to which has been added1g of anhydrous sodium carbonate and1g of potassium permanganate. Reject t
44、he first100ml of distillate and then collect about300ml. 6) Nesslers reagent, prepared by either of the following methods: a) Dissolve5g of potassium iodide in3.5ml of water. Add cold saturated mercury(II) chloride (HgCl 2 ) solution, while stirring, until a faint red precipitate is formed. With con
45、tinued stirring add40ml of50% potassium hydroxide solution, dilute to100ml with water, mix well, allow to settle, decant the clear supernatant liquid and store it in the dark. or b) Dissolve3.5g of potassium iodide and1.25g of mercury(II) chloride in80ml of water. Add cold saturated mercury(II) chlo
46、ride solution, while stirring, until a slight red precipitate remains, then add12g of sodium hydroxide, stir until dissolved, and finally add a little more saturated mercury(II) chloride solution and dilute to100ml with water. Stir occasionally during several days, allow to stand, and use the clear
47、supernatant liquid for the test. 5.3.3.2 Apparatus 1) Distillation apparatus 2) Nessler cylinders,50ml. 5.3.3.3 Procedure Place50ml of the clear aqueous extract(5.3.1) into the distillation flask and dilute to150ml with ammonia-free water5). Add3g of Devardas alloy4) and30ml of sodium hydroxide solu
48、tion2) and close the apparatus at once. Place2ml of hydrochloric acid1) and30ml of ammonia-free water5) in the receiver. Warm the flask gently until the reaction starts and then allow the reaction to proceed gently for about half an hour. Then distil about70ml of liquid, the receiver being kept cool
49、 with running water. Make up the distillate to250ml with ammonia-free water5) and transfer5ml to a Nessler cylinder. Dilute to50ml with ammonia-free water5). Transfer5ml of ammonium chloride solution3) (equivalent to0.1% NO 3 ) into a similar Nessler cylinder and dilute to50ml with ammonia-free water. Add1ml of Nesslers reagent6) to each cylinder and mix each thoroughly. Allow both cylinders to stand for5min and compare the intensity of colour of the two solutions. 5.3.3.4 Expression of
