1、BRITISH STANDARD BS7446:1991 ISO3711:1990 Specification for Lead chromate pigments and lead chromate-molybdate pigments for paintsBS7446:1991 This British Standard, having been prepared under the directionof the Pigments, Paintsand Varnishes StandardsPolicy Committee, waspublished underthe authority
2、of theStandards Boardand comes into effecton 28June1991 BSI11-1999 The following BSI references relate to the work on this standard: Committee reference PVC/1 Draft for comment85/52821 DC ISBN 0 580 19741 7 Committees responsible for this British Standard The preparation of this British Standard was
3、 entrusted by the Pigments, Paints and Varnishes Standards Policy Committee (PVC/-) to Technical Committee PVC/1, upon which the following bodies were represented: Aluminium Powder and Paste Association British Cement Association British Railways Board Chemical Industries Association Oil and Colour
4、Chemists Association Paintmakers Association of Great Britain Ltd Titanium Pigment Manufacturers Technical Committee Zinc Development Association Amendments issued since publication Amd. No. Date CommentsBS7446:1991 BSI 11-1999 i Contents Page Committees responsible Inside front cover National forew
5、ord ii 1 Scope 1 2 Normative references 1 3 Classification 1 4 Required characteristics and associated tolerances 2 5 Sampling 3 6 Determination of total lead content 3 7 Determination of soluble lead content 6 8 Test report 7 Table 1 Classification of lead chromate pigments and lead chromate-molybd
6、ate pigments 2 Table 2 Essential requirements 2 Table 3 Conditional requirements 2 Publication(s) referred to Inside back coverBS7446:1991 ii BSI 11-1999 National foreword This British Standard has been prepared under the direction of the Pigments, Paints and Varnishes Standards Policy Committee. It
7、 is identical with ISO3711:1990 “Lead chromate pigments and lead chromate-molybdate pigments Specifications and methods of test”, published by the InternationalOrganization for Standardization (ISO). ISO3711:1990 was reprinted to correct errors and reissued by ISO in March1991. This BritishStandard
8、is identical with the reprinted edition of ISO3711. Cross-references International Standard Corresponding British Standard BS3483 Methods for testing pigments for paints ISO787-1:1982 Part A1:1983 Comparison of colour (Identical) ISO787-2:1981 Part B6:1982 Determination of matter volatile at105 C (I
9、dentical) ISO787-4:1981 Part C3:1982 Determination of acidity or alkalinity of the aqueous extract (Identical) ISO787-5:1980 Part B7:1982 Determination of oil absorption value (Identical) ISO787-7:1981 Part B3:1982 Determination of residue on sieve (water method, using a manual procedure) (Identical
10、) ISO787-8:1979 Part C2:1980 Determination of matter soluble in water (cold extraction method) (Identical) ISO787-9:1981 Part C4:1982 Determination of pH value of an aqueous suspension (Identical) ISO787-15:1986 Part A3:1988 Comparison of resistance to light of coloured pigments of similar types und
11、er specified light sources (Identical) ISO787-16:1986 Part A4:1988 Determination of the relative tinting strength and colour on reduction of coloured pigments using visual comparison (Identical) ISO787-20:1975 Part B5:1974 Comparison of ease of dispersion (oscillatory shaking method) (Technically eq
12、uivalent) ISO842:1984 BS4726:1986 Methods for sampling raw materials for paints and varnishes (Identical) ISO1042:1983 BS1792:1982 Specification for one-mark volumetric flasks (Identical) ISO3696:1987 BS3978:1987 Specification for water for laboratory use (Identical) ISO3856-1:1984 BS3900 Methods of
13、 test for paints Part B6:1986 Determination of “soluble” lead content (Identical) ISO4793:1980 BS1752:1983 Specification for laboratory sintered or fritted filters including porosity grading (Identical)BS7446:1991 BSI 11-1999 iii The Technical Committee has reviewed the provisions of ISO385-1:1984 a
14、nd ISO648:1977, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. Related BritishStandards to ISO385-1 and ISO648 are BS846:1985, “Specification for burettes” and BS1583:1986, “Specification for one-mark pipettes”. A British S
15、tandard 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 from legal obligations. Summary of pages This document comprises a front cov
16、er, an inside front cover, pagesi to iv, pages1 to8, 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 table on the inside front cover.iv blankBS7446:1991 BSI 11-1999 1 1 Scope
17、This International Standard specifies the requirements and the corresponding methods of test for the following pigments identified by Colour Index numbers 1) : orange21, yellow34 and red104. These pigments are suitable for general use. NOTE 1The chemical identity of these pigments is given in Table
18、1. 2 Normative 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 t
19、his International 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. ISO385-1:1984, Laboratory glassware Burettes Part1: General requiremen
20、ts. ISO648:1977, Laboratory glassware One-mark pipettes. ISO787-1:1982, General methods of test for pigments and extenders Part1: Comparison of colour of pigments. ISO787-2:1981, General methods of test for pigments and extenders Part2: Determination of matter volatile at105 C. ISO787-4:1981, Genera
21、l methods of test for pigments and extenders Part4: Determination of acidity or alkalinity of the aqueous extract. ISO787-5:1980, General methods of test for pigments and extenders Part5: Determination of oil absorption value. ISO787-7:1981, General methods of test for pigments and extenders Part7:
22、Determination of residue on sieve Water method Manual procedure. ISO787-8:1979, General methods of test for pigments and extenders Part8: Determination of matter soluble in water Cold extraction method. ISO787-9:1981, General methods of test for pigments and extenders Part9: Determination of pH valu
23、e of an aqueous suspension. ISO787-15:1986, General methods of test for pigments and extenders Part15: Comparison of resistance to light of coloured pigments of similar types. ISO787-16:1986, General methods of test for pigments and extenders Part16: Determination of relative tinting strength (or eq
24、uivalent colouring value) and colour on reduction of coloured pigments Visual comparison method. ISO787-20:1975, General methods of test for pigments Part20: Comparison of ease of dispersion (Oscillatory shaking method). ISO842:1984, Raw materials for paints and varnishes Sampling. ISO1042:1983, Lab
25、oratory glassware One-mark volumetric flasks. ISO3696:1987, Water for analytical laboratory use Specification and test methods. ISO3856-1:1984, Paints and varnishes Determination of “soluble” metal content Part1:Determination of lead content Flame atomic absorption spectrometric method and dithizone
26、 spectrophotometric method. ISO4793:1980, Laboratory sintered (fritted) filters Porosity grading, classification and designation. 3 Classification In this International Standard, lead chromate pigments and lead chromate-molybdate pigments are classified as one of the following two types: Standard ty
27、pe (type1): Yellow to red pigments consisting of normal or basic lead chromate with or without lead sulfate and/or molybdate or other co-precipitated water-insoluble compounds of lead. Such pigments shall be free from organic colouring matter and shall not contain extenders. Pigments corresponding t
28、o pigment yellow Colour Index No.34 and pigment red Colour Index No.104 may contain co-precipitated compounds of, for example, aluminium and/or silicon when these are required solely for the control of the crystal structure of the pigment. 1) The Colour Index is published by The Society of Dyers and
29、 Colourists, PO Box244, Perkin House,82 Grattan Road, Bradford, West Yorkshire BD12JB, United Kingdom and the American Association of Textile Chemists and Colorists, National Headquarters, Box12215, Research Triangle Park, NC27709, USA.BS7446:1991 2 BSI 11-1999 Stabilized type (type2): Yellow to red
30、 pigments consisting of normal or basic lead chromate with or without lead sulfate and/or molybdate or other co-precipitated water-insoluble compounds of lead. These pigments contain other materials introduced during manufacture specifically to improve certain pigmentary properties. They shall be fr
31、ee from organic colouring matter and shall not contain extenders. If type2 is specified, the purchaser may require the vendor to state the nature of the improved properties which are claimed to result from the additions and to declare the minimum content of total lead. 4 Required characteristics and
32、 associated tolerances 4.1 For lead chromate pigments and lead chromate-molybdate pigments complying with this International Standard, the essential requirements are specified in Table 2 and the conditional requirements are listed in Table 3. The reference pigment and the conditional requirements li
33、sted in Table 3 shall be specified by agreement between the interested parties. 4.2 The agreed reference pigment shall comply with the requirements of Table 2. Table 1 Classification of lead chromate pigments and lead chromate-molybdate pigments Table 2 Essential requirements Table 3 Conditional req
34、uirements Type of pigment Shade of pigment Colour Index No. Chemical identity Lead chromate Primrose and lemon Pigment yellow No.34, Part2, Ref.77603 Lead sulfochromate Yellow Pigment yellow No.34, Part2, Ref.77600 Lead chromate Orange Pigment orange No.21, Part2, Ref.77601 Basic lead chromate Lead
35、chromate-molybdate Orange to red Pigment red No.104, Part2, Ref.77605 Lead sulfochromate-molybdate Characteristic Unit Requirement Method of test Matter volatile at105 C % (m/m) max.1 ISO787-2 Matter soluble in water (cold extraction method) % (m/m) max.2 ISO787-8, taking a test portion of20g Acidit
36、y or alkalinity of the aqueous extract ml of0,1 mol/l solution per100g of pigment max.20 ISO787-4, taking a test portion of20g pH value of aqueous suspension 4 to8 ISO787-9 Residue on sieve(454m) % (m/m) max.0,3 ISO787-7 Characteristic Unit Requirement Method of test Colour Equal to that of the agre
37、ed reference pigment (see4.2) to within a tolerance agreed between the interested parties ISO787-1 Colour on reduction ISO787-16 Relative tinting strength Ease of dispersion Shall not be inferior to that of the agreed reference pigment (see4.2) ISO787-20, measuring fineness of grind after2,5min,5min
38、 and thereafter every5min. Resistance to light Shall not be inferior to that of the agreed reference pigment (see4.2) ISO787-15 Oil absorption value Shall not differ by more than15% from the agreed value ISO787-5 Total lead content as Pb % (m/m) Shall not differ by more than3% (m/m) from the agreed
39、value See clause6 Soluble lead content as Pb in0,07mol/l HCl % (m/m) If required, to be agreed between the interested parties See clause7BS7446:1991 BSI 11-1999 3 5 Sampling Take a representative sample of the product to be tested, as described in ISO842. 6 Determination of total lead content For th
40、e determination of the total lead content, two methods (one gravimetric, the other titrimetric) are specified. The method to be used shall be agreed on between the interested parties. The gravimetric method(6.1) shall be used as the referee method in cases of dispute. 6.1 Gravimetric method 6.1.1 Pr
41、inciple Dissolution of the test portion in hydrochloric acid. Separation of the lead as lead sulfide and gravimetric determination of the lead after precipitation as lead sulfate and subsequent extraction with ammonium acetate. 6.1.2 Reagents During the analysis, use only reagents of recognized anal
42、ytical grade and only water of at least grade3 purity as defined in ISO3696. WARNING Use the reagents in accordance with the appropriate health and safety regulations. 6.1.2.1 Ammonium acetate, crystals. 6.1.2.2 Hydrogen sulfide 6.1.2.3 Tartaric acid 6.1.2.4 Nitric acid/bromine reagent Saturate nitr
43、ic acid, c(HNO 3 )=4mol/l, with bromine. 6.1.2.5 Hydrochloric acid, concentrated, approximately37% (m/m), 1,19g/ml. 6.1.2.6 Sulfuric acid, concentrated, approximately96% (m/m), 1,84g/ml. 6.1.2.7 Sulfuric acid, dilute. Dilute5ml of the concentrated sulfuric acid(6.1.2.6) by adding it to water, with c
44、ooling, and making up to100ml with water. 6.1.2.8 Ethanol, 95% (V/V). 6.1.2.9 Sodium sulfide, 50g/l solution, freshly prepared. 6.1.2.10 Ammonium acetate, saturated solution. 6.1.2.11 Ammonia solution, approximately25% (m/m), 0,91g/ml. 6.1.3 Apparatus Use ordinary laboratory apparatus and glassware
45、complying with the requirements of the relevant International Standards (see clause2), together with the following. 6.1.3.1 Sintered-glass crucibles, grade P16, complying with the requirements of ISO4793. 6.1.3.2 Sintered-silica crucibles, grade P16, complying with the requirements of ISO4793. 6.1.3
46、.3 Drying oven, capable of being maintained at105 C 2 C. 6.1.3.4 Muffle furnace, capable of being maintained at500 C 25 C. 6.1.4 Procedure Carry out the determination in duplicate. 6.1.4.1 Test portion Weigh out, to the nearest0,1mg, about0,5g of the sample (see clause5). 6.1.4.2 Determination Place
47、 the test portion(6.1.4.1) in a600ml beaker and add, as a reducing agent,2ml of ethanol(6.1.2.8), followed by100ml of water and15ml of hydrochloric acid(6.1.2.5). Cover the beaker with a watch-glass and heat to boiling. Boil gently until all odour of aldehyde has disappeared. Dilute to200ml with hot
48、 water. Filter the solution whilst hot through a fine filter paper and wash the filter and residue well with hot water until a few drops of the filtrate give no coloration with sodium sulfide solution(6.1.2.9). Combine the filtrate and washings and allow to cool to room temperature. Slowly add ammon
49、ia solution(6.1.2.11), whilst stirring, until a faint permanent precipitate forms. Then add0,5g of tartaric acid(6.1.2.3) and hydrochloric acid(6.1.2.5), until the pH-value of the solution is between1 and2. Pass hydrogen sulfide(6.1.2.2) through the solution in a fume cupboard until it is saturated. Dilute the solution to400ml and again saturate with hydrogen sulfide. Allow the precipitated lead sulfide to settle, preferably overnight, and pour off the clear supernatant liquor through a sintered-
