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1、BRITISH STANDARD BS 7387:1991 Method for Determination of the bulking thickness, apparent bulk density, compressibility and compressibility index of soft crped tissue paper Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 14:39:21 GMT+00:00 2006, Uncontrolled Cop
2、y, (c) BSI BS 7387:1991 This British Standard, having been prepared under the direction of the Paper and Printing Standards Policy Committee, was published under the authority of the Board of BSI and comes into effect on 31 January 1991 BSI 01-2000 The following BSI references relate to the work on
3、this standard: Committee reference PAM/11 Draft for comment 89/47674 DC ISBN 0 580 19183 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Paper and Printing Standards Policy Committee (PAM/-) to Technical Committee PAM/11, upon which th
4、e following bodies were represented: British Fibreboard Packaging Association British Paper and Board Industry Federation (PIF) British Printing Industries Federation British Telecommunications plc Envelope Makers and Manufacturing Stationers Association Her Majestys Stationery Office Man-made Fibre
5、s Producers Committee Ministry of Defence Paper Sack Development Association Ltd. Pira (the Research Association for the Paper and Board, Printing and Packaging Industries) Post Office Society of British Printing Ink Manufacturers University of Manchester Institute of Science and Technology Amendmen
6、ts issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 14:39:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7387:1991 BSI 01-2000i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Definitions1
7、 3Principle1 4Apparatus1 5Sampling2 6Conditioning2 7Preparation of test pieces2 8Procedure2 9Expression of results3 10Precision3 11Test report4 Appendix A Compressibility and compressibility index5 Appendix B Verification of micrometer performance and calibration5 Figure 1 Positions of measurement o
8、n test piece3 Table 1 Pressure between pressure faces2 Table 2 Micrometer performance2 Publication(s) referred toInside back cover Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 14:39:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7387:1991 ii BSI 01-2000 For
9、eword This British Standard has been prepared under the direction of the Paper and Printing Standards Policy Committee at the request of the Association of Manufacturers of Soft Tissue Papers. This British Standard complements BS 3983 by providing a method for the determination of bulking thickness,
10、 apparent bulk density and compressibility of soft crped tissue paper which are excluded from BS 3983 because of the micrometer specification. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct appli
11、cation. 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 and ii, pages 1 to 6, an inside back cover and a back cover. This standard has been updated (see copyright date
12、) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 14:39:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7387:1991 BSI 01-20001 1 Scope This Britis
13、h Standard describes a method for the determination of the bulking thickness, apparent bulk density, compressibility and the compressibility index of soft crped tissue paper. The method may also be suitable for use with other soft, compressible papers, such as some types of filter paper, but it is n
14、ot intended for use on uncrped paper. NOTE 1In order to measure the compressibility index, measurement of thickness at two different pressures is necessary and because of differences in micrometer characteristics there may be more than one alternative pressure. NOTE 2The need to provide for the meas
15、urement of compressibility arises because of the compressible nature of soft crped tissue paper and the desire to obtain a measurement which would enable the thickness or roll diameter of the converted products to be predicted and controlled. No single static load can be selected which would fulfil
16、these conditions. However the measurement of thickness at two different pressures encompassing the range of converting pressure facilitates this. NOTE 3The titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this British Stan
17、dard the definitions given in BS 5497-1 apply together with the following. 2.1 bulking thickness, t thickness of a single sheet of paper, calculated from the thickness of several superimposed sheets (termed a pack), measured under an applied static load, using the method of test in this standard 2.2
18、 apparent bulk density mass per unit volume of paper expressed in grams per cubic centimetre and calculated from its grammage and bulking thickness 2.3 compressibility index, k the linear relationship between the natural logarithm of the applied test pressure and the observed thickness NOTEFor soft
19、tissue such a relationship is usually found over the range of pressure from 2 kPa to 50 kPa. This should be verified from the specific type of tissue being examined by plotting thickness against the logarithm of the applied pressure (a minimum of three pressures). The highest and lowest pressures em
20、ployed in this verification would be preferably the two levels which it is intended to use for the compressibility determination if formulae 1 and 2 of Appendix A are to be applied. The decision as to whether the logarithmic relationship is acceptable should be justified by normal statistical method
21、s. if t1 and t2 are the bulking thicknesses determined at corresponding pressures p1 and p2, then the compressibility index k is defined using the following formula: the bulking thickness t3 at any intermediate pressure p3 can be calculated from the following formula: t3 = k (lnp1 lnp3) + t1 the dim
22、ension of k is length, expressed in the same units as for t. It is related to compressibility although it does not have the dimensions of compressibility (see Appendix A) 2.4 compressibility, c the rate of change of thickness with respect to the applied pressure at any given pressure and thickness (
23、see Appendix A) 3 Principle 3.1 Measurement of the thickness of a pack of sheets of paper over a specified area and under a specific static load by means of a high precision micrometer. Expression of the results in terms of the bulking thickness per sheet. 3.2 Calculation of the apparent bulk densit
24、y of the paper from a knowledge of its grammage and bulking thickness. 3.3 Calculation of the compressibility index by measuring the bulking thickness at two specified static loads. 4 Apparatus 4.1 Dead-weight micrometer, provided with two plane, parallel, circular pressure faces, between which the
25、test piece is placed for measurement. The pressure exerted between the pressure faces during the thickness measurement is given in Table 1. The two pressure faces form an integral part of the micrometer, such that one face is fixed (the anvil) and the other is moveable in a direction perpendicular t
26、o the plane of the fixed face. k t1t2 p2lnlnp1 - -= Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 14:39:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7387:1991 2 BSI 01-2000 Table 1 Pressure between pressure faces A circular region of a test piece, nominall
27、y at least 200 mm2 in area, is subjected during the thickness measurement to the pressure exerted between faces with one face at least 15.5 mm in diameter and the second face of such a size that it is in contact with the whole area of the other face when the micrometer reads zero. NOTEIt is not poss
28、ible to specify a single face diameter because of the wide range of pressures. The performance of the micrometer is such that when calibrated according to the method given in Appendix B, the micrometer complies with Table 1 and Table 2 (see also 8.1). 4.2 Thickness gauges, corresponding to approxima
29、tely 10 %, 30 %, 50 %, 70 % and 90 % of the full scale reading of the micrometer with each gauge accurate to 1 m. Table 2 Micrometer performance 5 Sampling Select the sample in accordance with BS 3430. 6 Conditioning Condition the sample in accordance with BS 3431 and carry out the test piece prepar
30、ation and the test procedure under the same atmospheric conditions as used to condition the sample. 7 Preparation of test pieces Make up a pack of not less than eight sheets to form the test piece, ensuring that all the sheets are orientated the same way. Prepare at least four test pieces, ensuring
31、that there are the same number of sheets in each. NOTE 1The test piece should be of sufficient size to provide for the number of tests and the surrounding handling area. A convenient size is 200 mm 250 mm (see Figure 1). NOTE 2It is essential that the test area of the test piece is not compressed at
32、 any time during sampling or preparation. NOTE 3When agreed between manufacturer and user a different size of sheet may be used. The size used should be reported. NOTE 4The sheets should be orientated so that the machine direction of all the sheets is aligned. The relative disposition of the top and
33、 wire sides of the sheets is not considered to be relevant. 8 Procedure 8.1 Verification and calibration of micrometer At appropriate time intervals, calibrate the micrometer and verify its performance using the method given in Appendix B. For micrometers in frequent use, determine the indication er
34、ror and repeatability measurement daily. 8.2 Determinations 8.2.1 Bulking thickness Place the micrometer on a horizontal vibration-free surface and interpose the test piece between the open pressure faces of the micrometer. Permit the test piece to be held by the pressure faces by very carefully all
35、owing the moveable pressure face to move steadily and slowly, at a velocity less than 3 mm/s, towards the fixed pressure face so that any punching effect is avoided. Record the micrometer reading as soon as its value becomes steady, but before any bedding down of the paper can occur. Avoid imposing
36、any manual stress on the test piece or micrometer while a reading is being made. Make one measurement at each of at least five positions in the test area as indicated in Figure 1, avoiding the handling/cutting area. Carry out measurements on at least four test pieces. NOTEThe test may be conducted a
37、t one or more of the pressures listed in Table 1. This may involve the use of a second micrometer. 8.2.2 Apparent bulk density If the apparent bulk density of the paper is to be calculated (see 9.2), determine the grammage of the sample by the method described in BS 3432. Pressure (see note 3)Tolera
38、nce kPa 2.0 3.5 10.0 20.0 50.0 kPa 0.2 0.35 1.0 2.0 5.0 NOTE 1All pressures have equal status. NOTE 2Other pressures within the range 0 kPa to 50 kPa are acceptable. NOTE 3Based on commercially available instruments. Micrometer characteristicMaximum value Indication error Error of parallelism betwee
39、n pressure faces Repeatability of measurement (as standard deviation) 2.5 m or 0.5 % 5 m or 1 % 2.5 m or 0.5 % NOTE 1The maximum value of a micrometer characteristic is the greater of the two values quoted for it in the table. NOTE 2Where a tolerance is expressed in the form of a percentage, it is b
40、ased upon the thickness of the test piece under test. Thus, it is possible for a given micrometer to comply with the table for some materials, but not for others. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 14:39:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI
41、 BS 7387:1991 BSI 01-20003 8.2.3 Compressibility index, k Determine the bulking thickness as described in 8.2.1, using two different pressures. Calculate the compressibility index k by the formula given in 9.3. 8.2.4 Compressibility, c If the compressibility c is to be calculated, use the formula gi
42、ven in Appendix A. 9 Expression of results 9.1 Bulking thickness 9.1.1 Calculate the mean value of the readings (not less than 20). Divide it by the number of sheets comprising each test piece to obtain the bulking thickness of a single sheet of paper and express the result, in micrometres, to three
43、 significant figures. 9.1.2 Calculate the standard deviation of the bulking thickness. 9.1.3 Calculate the precision of the mean at the 95 % confidence level. 9.2 Apparent bulk density Calculate the apparent bulk density, in grams per cubic centimetre from the formula: Report the results to two deci
44、mal places. 9.3 Compressibility index, k If required, calculate the compressibility index from the formula: where t1 and t2 are the bulking thicknesses of the paper in micrometres at the two corresponding pressures p1 and p2. The dimension of k is length expressed in micrometres if the thickness is
45、in micrometres. 9.4 Compressibility, c For details of compressibility, see Appendix A. 10 Precision 10.1 Bulking thickness 10.1.1 Repeatability value, r In tests in a limited number of laboratories using the same method on identical test material in the same laboratory by the same operator using the
46、 same apparatus within a short space of time, r has been observed to be within the range 2 % to 11 % of the mean. 10.1.2 Reproducibility value, R In tests in a limited number of laboratories using the same method on identical test material in different laboratories by different operators using diffe
47、rent apparatus, R has been observed to be within the range 4 % to 11 % of the mean. NOTEAll dimensions are in millimetres. Figure 1 Positions of measurement on test piece where gis the grammage of the paper (in g/m2); tis the bulking thickness of the paper (in m). g t - - k t1t2 p2lnlnp1 - -= Licens
48、ed Copy: London South Bank University, London South Bank University, Fri Dec 08 14:39:21 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7387:1991 4 BSI 01-2000 10.2 Apparent bulk density, compressibility index and compressibility Repeatability and reproducibility for these measurements have not been
49、evaluated, but are likely to be of the same order of magnitude as for bulking thickness. NOTEIt is desirable that estimates of r and R will be included in future revisions of this standard. 11 Test report The test report shall include the following particulars: a) reference to this standard; b) precise identification of the sample; c) date and place of testing; d) the conditioning atmosphere used; e) the pressure(s) exerted between the micrometer pressure faces; f) the