1、BRITISH STANDARD BS 4497:1969 Recommendations for The detection and estimation of nitrogenous treating agents in paperBS4497:1969 These Recommendations, havingbeen approved by the Paper Industry Standards Committee,were published underthe authority of the Executive Board on 28 October 1969 BSI 04-20
2、00 The following BSI references relate to the work on these recommendations: Committee reference PAC/11 Draft for comment 67/22978 ISBN 0 580 05652 X The following is a list of members of the Paper Industry Standards Committee, who have had the preparation of these recommendations under consideratio
3、n: The following is a list of members of the Technical Committee on Methods of Test for Paper, Board and Pulp, the Committee actually responsible for the preparation of these recommendations: Chairman: Mr. G. F. Underhay Vice-Chairman: Mr A. C. Vincent Miss W. E. Broom Mr. S. Bailey Board of Trade N
4、ational Association of Paper Mr. Gilbert A. Smith Merchants British Federation of Master Dr. N. K. Bridge Printers Research Association for the Paper Mr. R. W. H. Bray, A.F.C. and Board, Printing and Packaging Mr. E. E. Capon Industries (PIRA) Mr. J. Harding Dr. J. F. Heggie Mr. S. H. Hough Royal In
5、stitute of Public Health and Hygiene British Paper and Board Makers Association (Incorporated) Mr. F. M. Bolam Mr. J. Leather Mr. N. P. Brown British Railways Board Mr. I. F. Hendry Mr. K. Timberlake Mr. H. R. Hutley Coated Paper and Board Makers Mr. L. A. Lawrence Association Mr. J. F. A. Rankin Mr
6、. A. D. P. Tanner Mr. G. Thompson Envelope Makers and Technical Section of the British Manufacturing Stationers Paper and Board Makers Association Association Mr. F. E. Ashman H.M. Stationery Office Chairman: Mr. H. R. Hutley Dr. George L. Fuchs Mr. H. A. Idle Mr. G. J. Strode Society of British Pri
7、nting Ink British Federation of Master Manufacturers Printers Mr. J. D. Batley Mr. A. Baker Mr. F. M. Bolam British Paper and Board Makers Mr. N. P. Brown Association (Incorporated) Mr. G. Cameron Mr. E. C. Allison Mr. C. A. Chester Mr. Michael J. Ford Dr. W. J. Dodds British Wood Pulp Association M
8、r. C. F. Finney Mr. E. D. Garner Mr. G. F. Glover Chemical Industries Association Mr. F. J. T. Harris Mr. H. F. Church Mr. F. W. Hayward Electrical Research Association Mr. I. F. Hendry Mr. G. R. Keay Mr. L. F. Hopkins Envelope Makers and Manufacturing Stationers Association Mr. K. A. Hyam Mr. L. A.
9、 Lawrence Mr. A. N. May Mr. J. A. Moore Mr. R. Peerless Fibreboard Packing Case Mr. J. F. A. Rankin Manufacturers Association Mr. J. R. Simmons Mr. W. J. R. Howell Technical Section of the British H.M. Stationery Office Paper and Board Makers Mr. R. R. Coupe Association London College of Printing Mr
10、. E. MytumBS4497:1969 Mr. J. W. More Textile Institute Man-made Fibre Producers Mr. P. Howarth Committee University of Manchester Mr. C. F. Finney Mr. W. D. L. Anderson Ministry of Defence, Army Nominated by Technical Committee Department DPE/2 Punched Cards, Dimensions Mr. J. A. Simmons and Propert
11、ies Post Office Mr. C. F. Finney Mr. R. J. Hamer Nominated by Technical Committee Mr. F. D. Munday DPE/3 Punched Tape, Dimensions Research Association for the Paper and Properties and Board, Printing and Packaging Industries (PIRA) Amendments issued since publication Amd. No. Date CommentsBS4497:196
12、9 ii BSI 04-2000 Contents Page Co-operating organizations Inside front cover Foreword iii Introduction 1 1 Scope 1 2 Qualitative tests 1 2.1 General 1 2.2 Dye staining method 1 2.3 Xanthydrol test for urea resins 3 2.4 Melamine picrate test for melamine resins 4 2.5 Tests for polyethylenimine 4 2.6
13、Epoxypolyamine resins 5 2.7 Formaldehyde tests 5 2.8 Protein tests 6 3 Quantitative estimation 8 3.1 Principle 8 3.2 Equipment 8 3.3 Sampling 9 3.4 Procedure 9 3.5 Reporting procedure 9 3.6 Test report 10 Table 1 Dye staining test results 3BS4497:1969 BSI 04-2000 iii Foreword These recommendations m
14、ake reference to the following British Standards: BS 3430, Sampling of paper and board for testing. BS 3431, Conditioning of paper and board test samples. The committee concerned with methods of test for paper, board and pulp has already produced a considerable number of British Standard test method
15、s and has an extensive programme of work in hand. There are several instances in which it would be desirable to prepare standard methods for determining certain properties of paper and board but in the present state of knowledge this is not practicable. Experience has shown that there are instances,
16、 for example, in which a test is satisfactory only for a limited application, or that a method is suitable for mill control purposes but not sufficiently precise for use in case of a dispute. Nevertheless, it is felt that the issue of some of these test methods in the form of recommendations rather
17、than as British Standard methods will be helpful to users. These recommendations are, therefore, published under the authority of the Paper Industry Standards Committee. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsi
18、ble 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 cover, an inside front cover, pages i to iv, pages1to 10 and a back cover. This standard has been updated (see copyright d
19、ate) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankBS4497:1969 BSI 04-2000 1 Introduction A number of important substances used in the treatment of paper contain relatively constant amounts of nitrogen and, by estimating the
20、 nitrogen content of a given sample, a fairly accurate idea of the quantity of treating agent can be obtained. The substances most frequently determined in this way are melamine-formaldehyde and urea-formaldehyde resins, gelatin (or glue) and casein. Mixtures of these substances in paper cannot be d
21、etermined by this method and, of course, any other nitrogenous substances present in the paper would interfere with the result. Other nitrogenous wet strengthening agents are polyethylenimine and epoxypolyamine resins, neither of which contains formaldehyde. All of these substances have a strong aff
22、inity for acid dyes and it is this class only that is dealt with in these recommendations. Polyacrylamide is added to paper to increase dry strength, but this material does not react to any of the tests in these recommendations. Other nitrogenous substances which may be found in paper, but which are
23、 not dealt with, are cellulose nitrate and polyamide resins (which might occur in specialized coatings), aniline-formaldehyde and polyvinyl carbazole resins (which are used for impregnating), butadiene acrylonitrile copolymer (which is a synthetic rubber used for making imitation leather) and leathe
24、r dust itself (which is added to some types of leatherboard). Deeply coloured papers may also contain an appreciable amount of nitrogen according to the type of dye used, while nitrogenous mordants may occasionally be employed. Soya protein and other vegetable proteins such as those from maize and g
25、round nuts are occasionally used as casein substitute and, as they give reactions similar to those of casein, would be classed with it in the tests given in these recommendations. 1 Scope These recommendations describe the problems of the detection and estimation of nitrogenous treating agents in pa
26、per, and describe both qualitative and quantitative methods for use with certain of these agents; the methods are confined to those substances that have a strong affinity for acid dyes. 2 Qualitative tests 2.1 General. The most useful sorting test for nitrogenous treating agents is the dye staining
27、test, although it does not give specific identification of melamine-formaldehyde resin. For positive identification of any resin, it is necessary to apply one or more confirmatory tests, and these are given in the following clauses for formaldehyde, urea, melamine, polyethylenimine and the proteins.
28、 2.2 Dye staining method. This test is based on the fact that, although acid dyestuffs will not dye cellulose unless mordanted, they combine readily with proteins, such as casein and gelatin, and with many synthetic nitrogenous substances, such as the amino-aldehyde resins. Acid dyes will, therefore
29、, be absorbed by paper that has been treated with those substances, while other types of paper remain relatively undyed. The test is made partially selective by varying the acidity and temperature of the dye and by subjecting the paper to various pre-treatments. It shows the presence of melamine-for
30、maldehyde or other acid resistant resin and gives a good indication of the presence of casein or hardened gelatin. The test also shows the presence of urea-formaldehyde resins, but the colour produced by them is comparatively weak and paper containing much less than1% may be no more deeply stained t
31、han some types of untreated paper. The results given in this test by different treating agents are shown inTable 1. A suitable dyestuff is Solway Blue BS (or BNS) (Colour Index Reference63010C.1. Acid Blue45). Stock solutions are as follows: A 0.1% solution Solway Blue BS (or BINS) containing 0.1% s
32、ulphuric acid by weight. B 0.1% solution Solway Blue BS (or BNS) containing 1.0% sulphuric acid by weight. C 1.0% solution caustic soda. D 2.0% solution sulphuric acid by weight (about 0.4N).BS4497:1969 2 BSI 04-2000 2.2.1 Dyeing procedures. Test pieces about30mm square are cut from the paper to be
33、tested and, if possible, it is convenient to have untreated paper of a similar type to act as control sheets. This is very important if the paper is heavily sized or tinted or if more than about10% of mechanical woodpulp is present. 2.2.1.1 Procedure I. Immerse a test piece of the paper under examin
34、ation and also of the control sheet (if available) in solution A at room temperature in a glass beaker or similar container. Swirl the beaker occasionally to ensure even dyeing and after5min remove the test pieces and wash for a minute or two in cold water. The control sheet should now be colourless
35、 or in some cases pale blue; a strong blue in the sample indicates the presence of a “protein-like” substance. 2.2.1.2 ProcedureII. Take two test pieces and label these X and Y. 1) Pretreat test piece X by boiling for5min in solution D. 2) Dye test pieces X and Y in solution B for5min at the boil. W
36、ash the test pieces as before. A considerable difference in the blue colour between test piecesX andY or the retention of less colour by both than in ProcedureI indicates the presence of a urea resin or possibly a protein. Little or no difference in colour indicates the presence of a substance resis
37、tant to hydrolysis (for example, melamine resin or polyethylenimine). In this procedure, the hot acid hydrolyses urea-formaldehyde resins and also the proteins in many cases, but the higher temperature causes the less easily hydrolysed substances to be dyed more deeply than in ProcedureI. 2.2.1.3 Pr
38、ocedureIII. Boil the test pieces in solutionC for5min. Wash carefully in three500ml portions of cold water and then carry out the test described in ProcedureII. The pretreatment with caustic soda removes urea resin, glue and casein. 2.2.2 Notes on the interpretation of results. The epoxypolyamine re
39、sins are new wet strength resins that do not need a low pH to achieve a cure and are therefore more likely to be found in absorbent papers. They do not contain formaldehyde and give no reaction to any of the other tests in these recommendations. Their reaction to the dye test is similar to that of m
40、elamine resin except that there is much less difference in colour between ProceduresI andII. The use of two separate treatments under ProcedureII is necessitated by the introduction of certain types of cationic urea resins that give abnormal reactions to the original dye staining test. Papers treate
41、d with these resins stain as deeply as melamine-formaldehyde treated samples in ProcedureII(2) but when pretreated with hot acid as in ProcedureII(1), sufficient resin is removed to show a marked reduction in colour compared with melamine resins. Strongly hardened casein may sometimes be confused wi
42、th melamine resin by the dye test, but if the sodium hydroxide treatment in ProcedureIII is extended or the strength of the solution increased to2%to3%, the colour given by casein treated papers in ProcedureIII should be noticeably less than in ProcedureII(2). Paper containing much mechanical woodpu
43、lp will stain as if it contains a little melamine resin and, although the formaldehyde test will be negative in an untreated paper, some confusion might arise with a paper containing both urea resin and mechanical pulp. In this case it is essential to include an untreated blank containing approximat
44、ely the same amount of mechanical pulp when carrying out the dye staining tests. Some sized papers and others containing much alum may stain slightly in ProcedureI and thus be confused with urea-formaldehyde treated paper, while some types of sizing, notably wax size, may prevent absorption of the c
45、old dye solution and thus give reduced staining. This latter trouble may be overcome by the addition of a few drops of a nonionic wetting agent to the dye solution in ProcedureI. Whether or not all three dyeing procedures need to be applied to a given paper depends upon the amount of information alr
46、eady available, for example, if it is known that the paper does not contain a protein, then ProcedureIII may be omitted; if it is only required to differentiate between melamine and urea-formaldehyde treated papers, then ProceduresII(1) andII(2) are all that are necessary; if a distinction is needed
47、 between untreated papers and papers containing melamine- or urea-formaldehyde resin or a protein, then ProcedureI is all that need be applied.BS4497:1969 BSI 04-2000 3 2.2.3 Coloured papers. The dye test is of limited use on coloured papers, but if the colour can be removed by ordinary bleach liquo
48、r (calcium or sodium hypochlorite solution) further information may be obtained. The reactions of melamine-formaldehyde and some grades of urea-formaldehyde resins are not affected by the bleaching and normal dyeing is obtained. Gelatin, casein and some types of urea resin are affected by the bleach
49、 and no longer give a positive dye test. Polyethylenimine and the epoxypolyamines may be affected to some extent and the coloration on dyeing thus reduced. A complication with dyed papers is the possibility that fixing agents may be present to improve the retention of the dye. Since some of these agents are not affected by bleach liquor they will remain in the paper after bleaching and may give a positive dye test when no other treating agent is present. Several of these dye fixing agents contain nitrogen and at least one is a modified urea resin. Table 1 Dye
