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1、BRITISH STANDARD BS ISO 22891:2007 Paper Determination of transmittance by diffuse reflectance measurement ICS 85.060 ? Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:52:02 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS ISO 22891:2007 This British Standard wa
2、s published under the authority of the Standards Policy and Strategy Committee on 31 August 2007 BSI 2007 ISBN 978 0 580 54137 7 National foreword This British Standard is the UK implementation of ISO 22891:2007. The UK participation in its preparation was entrusted to Technical Committee PAI/11, Me
3、thods of test for paper, board and pulps. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a B
4、ritish Standard cannot confer immunity from legal obligations. Amendments issued since publication Amd. No. DateComments Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:52:02 GMT+00:00 2007, Uncontrolled Copy, (c) BSI Reference number ISO 22891:2007(E) INTERN
5、ATIONAL STANDARD ISO 22891 First edition 2007-07-01 Paper Determination of transmittance by diffuse reflectance measurement Papier Dtermination de la transmittance par le mesurage de la rflectance diffuse BS ISO 22891:2007 Licensed Copy: London South Bank University, London South Bank University, Sa
6、t Aug 18 09:52:02 GMT+00:00 2007, Uncontrolled Copy, (c) BSI ii Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:52:02 GMT+00:00 2007, Uncontrolled Copy, (c) BSI iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references. 1 3 Terms and def
7、initions. 1 4 Principle. 3 5 Apparatus 3 6 Sampling 4 7 Preparation of test pieces 4 8 Procedure 4 9 Calculation. 4 10 Precision 5 11 Test report . 5 Annex A (normative) Spectral characteristics of reflectometers for measuring luminous reflectance factors 6 Annex B (informative) Relationship between
8、 transmittance and opacity 8 Bibliography. 9 BS ISO 22891:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:52:02 GMT+00:00 2007, Uncontrolled Copy, (c) BSI iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of n
9、ational standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. Inter
10、national organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the
11、 rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by
12、 at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 22891 was prepared by Technical Committee ISO
13、/TC 6, Paper, board and pulps. BS ISO 22891:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:52:02 GMT+00:00 2007, Uncontrolled Copy, (c) BSI v Introduction This International Standard presents a method of determining the transmittance indirectly from ref
14、lectance factor data obtained by measurement under specified conditions. The equation used to calculate the transmittance is based on the Kubelka-Munk theory of light scattering and light absorption, and the equation can therefore only be strictly applied if measurements are made on materials which
15、scatter light sufficiently to justify the application of this theory. The reflectance factor depends on the conditions of measurement, and particularly on the spectral and geometric characteristics of the instrument used for its determination. This International Standard should therefore be read in
16、conjunction with ISO 2469 and ISO 2471. The transmittance value obtained by this method is a single value compatible with the opacity value determined according to ISO 2471, since all measurements are related to the luminance factor calculated with respect to the CIE illuminant C. The method describ
17、ed in this International Standard gives only the total transmittance and does not distinguish between regular transmittance and diffuse transmittance. It does not provide a direct measure of the ability to distinguish, for example, written text through a transparent medium. This can be assessed only
18、 if the ratio of the regular to the diffuse transmittance is known. It is emphasised that this method is for the determination not of the transmittance by direct measurement but of the transmittance obtained indirectly from reflectance factor measurements. Under ideal conditions they are the same, b
19、ut in practice it may be necessary to emphasise the difference. BS ISO 22891:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:52:02 GMT+00:00 2007, Uncontrolled Copy, (c) BSI blank Licensed Copy: London South Bank University, London South Bank University,
20、 Sat Aug 18 09:52:02 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 1 Paper Determination of transmittance by diffuse reflectance measurement 1 Scope This International Standard specifies a method for the calculation of transmittance based upon diffuse reflectance measurements. The use of the method is
21、restricted to white and near-white translucent papers (see 3.9). If it is necessary to determine the transmittance of papers which contain fluorescent whitening agents, the fluorescence emission is eliminated using the prescribed UV cut-off filter. NOTE This means that, although this International S
22、tandard refers to ISO 2469 which permits the use of both filter colorimeters and abridged spectrophotometers, a filter colorimeter with no means of eliminating the emission of fluorescence is not suitable for this type of measurement if fluorescent whitening agents are present. 2 Normative reference
23、s The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 186, Paper and board Sampling to determine
24、average quality ISO 2469, Paper, board and pulps Measurement of diffuse radiance factor ASTM E308-06, Standard Practice for Computing the Colors of Objects by Using the CIE System 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 reflectance fa
25、ctor R ratio of the radiation reflected by a body to that reflected by the perfect reflecting diffuser under the same conditions of illumination and detection NOTE This ratio is often expressed as a percentage. 3.2 luminance factor (C) Ry reflectance factor weighted with reference to the colour matc
26、hing function y() of the CIE 1931(2) Standard Observer and the CIE illuminant C NOTE 1 This property corresponds to the attribute of visual perception of the luminance of the reflecting surface. The strict definition refers to the visual efficient function V(). Since this function is identical with
27、the y() function, the latter is BS ISO 22891:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:52:02 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 2 preferred here, since it is more familiar in a paper technology context and it is this function which is indic
28、ated in connection with the ASTM E308 tables necessary for the computations. NOTE 2 Since the concept of “luminance” embodies the y() function of the CIE 1931(2) Standard Observer, it is only necessary to add the qualification (C) to indicate the CIE illuminant C, and not the more common (C/2). 3.3
29、single-sheet luminance factor (C) R0 luminance factor (C) of a single sheet of paper with a black backing 3.4 intrinsic luminance factor (C) R luminance factor (C) of a layer or pad of material thick enough to be opaque, i.e. such that increasing the thickness of the pad by doubling the number of sh
30、eets results in no change in the measured luminance factor 3.5 transmittance ratio of the transmitted radiant or luminous flux to the incident flux under given conditions CIE Publication 17.4:1987, 845-04-59 3.6 regular transmittance r ratio of the regularly transmitted part of the (whole) transmitt
31、ed flux to the incident flux CIE Publication 17.4:1987, 845-04-61 3.7 diffuse transmittance d ratio of the diffusely transmitted part of the (whole) transmitted flux to the incident flux CIE Publication 17.4:1987, 845-04-63 NOTE = r + d. 3.8 transparent medium medium in which the transmission is mai
32、nly regular and which usually has a high regular transmittance in the spectral range of interest CIE Publication 17.4:1987, 845-04-108 NOTE Objects may be seen distinctly through a medium which is transparent in the visible region, if the geometric form of the medium is suitable. 3.9 translucent med
33、ium medium which transmits visible radiation largely by diffuse transmission CIE Publication 17.4:1987, 845-04-109 NOTE Objects are not seen distinctly through a translucent medium. BS ISO 22891:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:52:02 GMT+0
34、0:00 2007, Uncontrolled Copy, (c) BSI 3 3.10 transmittance from reflectance factor measurements T transmittance obtained by measurement of reflectance factors and subsequent calculation as defined in this method 4 Principle The luminance factors of a single sheet of paper over a black body and over
35、a white body are determined by measurement according to standard procedures. The transmittance is calculated from the luminance factors. 5 Apparatus 5.1 Reflectometer, having the geometric, spectral and photometric characteristics described in ISO 2469, equipped for the measurement of the luminance
36、factor, and calibrated in accordance with the provisions of ISO 2469. 5.2 Filter-function: in the case of a filter reflectometer, a filter that, in conjunction with the optical characteristics of the basic instrument, gives an overall response equivalent to the CIE tristimulus value Y of the CIE 193
37、1 standard colorimetric system of the test piece evaluated for the CIE standard illuminant C. In the case of an abridged spectrophotometer, a function that permits calculation of the CIE tristimulus value Y of the CIE 1931 standard colorimetric system of the test piece evaluated for the CIE standard
38、 illuminant C using the weighting functions given in Annex A. The spectrophotometer should be fitted with a 420 nm UV cut-off filter for fluorescence elimination, as described in ISO 2469. 5.3 Reference standards, issued by an ISO/TC 6 authorized laboratory in accordance with the provisions of ISO 2
39、469 for calibration of the instrument and the working standards. For maximum accuracy, reference standards having assigned values within the maximum range expected for the particular product to be tested should be selected. If there is reason to suspect that the instrument has poor linearity or that
40、 the deviations from the true colour matching and observer functions are greater than can be tolerated, the use of product-specific reference standards should be considered. Use new reference standards sufficiently frequently to ensure that the reflectometer is maintained in agreement with the refer
41、ence instrument. 5.4 Two working standards, calibrated in the apparatus concerned against ISO reference standards of level 3 supplied by an authorized laboratory (see ISO 2469). Calibrate the working standards sufficiently frequently to ensure that satisfactory calibration is maintained. 5.5 Black c
42、avity, for calibration or validation of the low end of the photometric scale, and also for use as a black backing for some of the measurements. This black cavity shall have a radiance factor which does not differ from its nominal value by more than 0,2 percentage points at all wavelengths. The black
43、 cavity should be stored upside-down in a dust-free environment or with a protective cover. During calibration, the instrument shall be adjusted to the nominal value of the black cavity. It is not yet possible to institute a system of reference standards to enable testing laboratories to check the r
44、eflectance factor of the black cavity. At the time of delivery, the level should be guaranteed by the instrument maker. Questions concerning the use and condition of the black cavity should be resolved by contacting the instrument maker. 5.6 White backing, consisting of an opaque non-fluorescent whi
45、te material with a flat, matt surface. NOTE A pad of paper or a ceramic tile is suitable. BS ISO 22891:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:52:02 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 4 6 Sampling If the tests are being made to evaluate a
46、 lot, the sample should be selected in accordance with ISO 186. If the tests are made on another type of sample, make sure that the test pieces taken are representative of the sample received. 7 Preparation of test pieces Avoiding watermarks, dirt and obvious defects, cut at least five rectangular t
47、est pieces approximately 75 mm 150 mm. Place the test pieces between protecting sheets. Mark the test pieces in one corner to identify the sample and its top side. If the top side can be distinguished from the wire side, it shall be uppermost; if not, as may be the case for papers manufactured on do
48、uble-wire machines, ensure that the same side of the sheet is uppermost. 8 Procedure 8.1 If the test material contains or is suspected to contain a fluorescent whitening agent, make sure that the fluorescence emission is eliminated by inserting the 420 nm UV cut-off filter (see 5.2) into the light b
49、eam, as indicated in ISO 2469. 8.2 Using the procedure appropriate for the instrument in accordance with the manufacturers instructions, determine the luminance factor (C) of the white backing, Rw. Read and record the value to the nearest 0,01 % reflectance factor. 8.3 Without touching the test area, place the first test piece over the white backing and measure the reflectance factor R of the top side of the test piece. Read and record the value to the nearest 0,01 % reflecta
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