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GB/T 2679.1-2020 English PDF (GBT2679.1-2020)

GB/T 2679.1-2020 English PDF (GBT2679.1-2020)

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GB/T 2679.1-2020: Paper--Determination of transmittance--Diffuse reflectance measurement

This Part of GB/T 2679 specifies the method for determination of transmittance by diffuse reflectance measurement. This Part applies to white and near-white translucent paper. To measure paper containing fluorescent whitening agents, use a UV cut-off filter to eliminate fluorescence excitation. Note: Although GB/T 7973 allows the use of filter reflectometers and abridged spectrophotometers, if the filter reflectometer cannot eliminate the excitation of fluorescence, it is not suitable for testing the transmittance of paper containing fluorescent whitening agents.
GB/T 2679.1-2020
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 85.010
Y 30
Replacing GB/T 2679.1-2013
Paper - Determination of transmittance - Diffuse reflectance
measurement
(ISO 22891:2013, Paper - Determination of transmittance by diffuse
reflectance measurement, MOD)
ISSUED ON: JULY 21, 2020
IMPLEMENTED ON: FEBRUARY 1, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions ... 6
4 Principle ... 7
5 Apparatus ... 8
6 Sampling ... 9
7 Preparation of test pieces ... 9
8 Test procedure ... 9
9 Calculation ... 10
10 Test report ... 10
Annex A (Informative) Structural changes of this Part compared with ISO 22891:2013 ... 11
Annex B (Normative) Spectral characteristics of reflectometer for determining diffuse reflectance factor ... 12
Foreword
GB/T 2679 is currently divided into the following parts:
- GB/T 2679.1 Paper - Determination of transmittance - Diffuse reflectance measurement;
- GB/T 2679.2 Sheet materials - Determination of water vapour transmission rate - Gravimetric (Dish) method;
- GB/T 2679.6 Corrugating medium - Determination of the flat crush resistance after laboratory fluting;
- GB/T 2679.7 Board - Determination of puncture resistance;
- GB/T 2679.8 Paper and board - Determination of compressive strength (Ring crush method);
- GB/T 2679.10 Paper and board - Compressive strength - Short span test; - GB/T 2679.11 Paper and board - Qualitative analysis of mineral filler and mineral coating - SEM/EDAX Method;
- GB/T 2679.12 Paper and board - Qualitative analysis of mineral filler and mineral coating - Chemical method;
- GB/T 2679.14 Filter paper and filterboard - Determination of maximum pore diameter;
- GB/T 2679.17 Corrugated fibreboard - Determination of edgewise crush resistance (Edge reinforced method).
This Part is Part 1 of GB/T 2679.
This Part is drafted in accordance with the rules given in GB/T 1.1-2009. This Part replaces GB/T 2679.1-2013 ?€?Paper - Determination of transmittance - Diffuse reflectance measurement?€?. Compared with GB/T 2679.1-2013, the main technical changes are as follows:
- Add the term "White backing luminance factor" (see 3.4);
- Delete "Transmittance" (see 3.4 of the 2013 edition);
- Change the definition of "Transmittance from reflectance factor measurements" (see 3.5; 3.5 of the 2013 edition);
- Modify the "Filter-function" in the "Apparatus" (see 5.2; 5.2 of the 2013 edition); - Modify the measurement accuracy of luminance factor in the test procedure (see 8.2, 8.3 and 8.4; 8.2, 8.3 and 8.4 of the 2013 edition);
- Modify the labeling of Ry and R0 in the calculation (see Clause 9; Clause 9 of the 2013 edition);
- Add the structural changes of this Part compared with ISO 22891:2013 (see Annex A).
This Part uses the redraft law to modify and adopt ISO 22891:2013 "Paper - Determination of transmittance by diffuse reflectance measurement".
Compared with ISO 22891:2013, this Part has more adjustments in structure. Annex A lists the comparison of clause-subclause numbers between this Part and ISO 22891:2013.
The technical differences between this Part and ISO 22891:2013 and their reasons are as follows:
- As for the normative references, this Part has made adjustments with technical differences, to adapt to the technical conditions of China. The adjustments are mainly reflected in Clause 2 ?€?Normative references?€?. The specific adjustments are as follows:
??? Replace ISO 186 with GB/T 450, which modifies and adopts the international standard;
??? Replace ISO 2469 with GB/T 7973, which is not equivalent to the international standard;
??? Delete reference to ASTM E308-06.
- Change the definition of the term "Luminance factor". Use "CIE standard illuminant D65 and CIE 1964 supplementary standard chromaticity system" to replace "CIE standard illuminant C and CIE 1931 standard chromaticity system in ISO 22891:2013", to be consistent with the instruments and related standards for measuring paper color in China's paper industry (see 3.2 and 5.2).
- Delete the terms "Intrinsic luminance factor", "Transmittance", "Regular transmittance", "Diffuse reflectance transmittance", "Transparent medium", and "Translucent medium", to meet the technical conditions of China.
- Replace the luminance factor (C), the single-sheet luminance factor (C) and the white backing luminance factor (C) in the standard WITH the luminance factor (D65), the single-sheet luminance factor (D65) and the white backing luminance factor (D65) respectively; to be consistent with the technical conditions of test instruments in China (see 3.2, 3.3, 3.4, 3.5, 8.2, 8.3, 8.4).
- Modify the provisions of filter reflectometer and abridged spectrophotometer, to be consistent with the technical conditions of test instruments in China (see 5.2 and Annex B).
- Add the requirement that "The Ry value of the backing is (84.0??1.0)%", to eliminate the result deviation caused by the white backing (see 5.6).
- Modify the calculation formula in the calculation, to be consistent with the technical conditions of test instruments in China (see Clause 9).
- Modify Annex A "Spectral characteristics of reflectometer for determining diffuse reflectance factor" of ISO 22891:2013 (see Annex B).
- Delete Annex B, Annex C, and Bibliography of ISO 22891:2013. The content of these parts is not suitable for China's national conditions.
This Part makes the following editorial change:
- Change the standard name.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing authority of this document shall not be held responsible for identifying any or all such patent rights.
This Part was proposed by China National Light Industry Council.
This Part shall be under the jurisdiction of National Technical Committee 141 on Paper Industry of Standardization Administration of China (SAC/TC 141).
Drafting organizations of this Part: Hangzhou Fuyang Institute of Measurement for Quality and Technique Supervision, Zhejiang KAN Special Materials Co., Ltd., Minfeng Special Paper Co., Ltd., Zhejiang Hua Feng Paper Group Co., Ltd., Zhejiang Xinfeng Special Paper Co., Ltd., Qingdao Jiaze Packaging Co., Ltd., China National Pulp and Paper Research Institute Co., Ltd.
Main drafters of this Part: Wo Qizhong, Ge Jinlan, Chen Hua, Cheng Yimin, Zhou Minghua, Li Dafang, Wang Qiuting, Wang Xiaoli, Bai Meiqiao, Zhang Zhilong. The previous editions of the standard replaced by this Part were released as follows: - GB 2679.1-1981, GB/T 2679.1-1993, GB/T 2679.1-2013.
Paper - Determination of transmittance - Diffuse reflectance
measurement
1 Scope
This Part of GB/T 2679 specifies the method for determination of transmittance by diffuse reflectance measurement.
This Part applies to white and near-white translucent paper. To measure paper containing fluorescent whitening agents, use a UV cut-off filter to eliminate fluorescence excitation.
Note: Although GB/T 7973 allows the use of filter reflectometers and abridged spectrophotometers, if the filter reflectometer cannot eliminate the excitation of fluorescence, it is not suitable for testing the transmittance of paper containing fluorescent whitening agents. 2 Normative references
The following documents are indispensable for the application of this document. For the dated references, only the editions with the dates indicated are applicable to this document. For the undated references, the latest edition (including all the amendments) are applicable to this document.
GB/T 450 Paper and board - Sampling for testing and identification of machine and cross direction, wire side and felt side (GB/T 450-2008, ISO 186:2002, MOD) GB/T 7973 Paper, board and pulps - Measurement of diffuse reflectance factor (Diff/Geometry) (GB/T 7973-2003, ISO 2469:1994, NEQ)
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Reflectance factor
The ratio OF the radiant flux reflected by an object TO the radiant flux reflected by a perfect reflecting diffuser under the same conditions.
5 Apparatus
5.1 Reflectometer
The geometric, optical, and spectral characteristics of the instrument shall comply with the provisions of GB/T 7973. It shall have the function of luminance factor measurement. It shall be calibrated according to the provisions of GB/T 7973. 5.2 Filter or function
Filter reflectometers shall choose matching filters, so that the overall spectral characteristics of the instrument are consistent with the tristimulus value Y10 of the CIE 1964 supplementary standard chromaticity system under the CIE standard illuminant D65.
For an abridged spectrophotometer, the instrument shall be equipped with a 420 nm UV cut-off filter. And according to the weighting coefficients in Annex B, the CIE 1964 supplementary standard chromaticity system tristimulus value Y10 of the tested sample under the CIE standard illuminant D65 can be calculated.
5.3 Reference standards
Provided by an authorized laboratory, it shall comply with the calibration regulations on apparatus and working standards in GB/T 7973. If it is necessary to measure special products, in order to ensure the highest accuracy, within the maximum range, there are reference standards with different fixed values for selection when testing special products.
If the linearity error of the instrument is large, or the deviation between the measurement result and the color matching/the true value of observer function exceeds the allowable value, a special reference standard shall be considered.
Effectively and frequently use the latest calibrated reference standards, to ensure that the instrument is consistent with the reference instrument.
5.4 Working standards
Use a level 3 reference standard issued by an authorized laboratory to calibrate the instrument. The working standard shall be cleaned and calibrated according to the provisions of GB/T 7973, to ensure the accuracy of the calibration value. 5.5 Black cavity
In the full wavelength range, the difference between the reflectance factor and the nominal value shall not exceed 0.2%. The black cavity shall be placed in a dust-free environment; and shall be placed with the opening facing down, or equipped with a

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