This standard specifies the method for measuring the transparency of paper by irradiating with green light and backing with a white board with a specified reflection factor. This standard is applicable to the determination of the transparency of white or nearly white translucent paper, tracing paper and other papers. Note: The determination of the transparency of colored translucent paper can be carried out in accordance with the method specified in this standard, but only for comparison between papers of the same color. GB/T 2679.1-1993 Method for determining the transparency of paper GB/T2679.1-1993 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of paper transparency
Paper---Determination of transparent1 Subject content and scope of application
This standard specifies the method for determining the transparency of paper by irradiating with green light and backing with a white board with a specified reflection factor. This standard is applicable to the determination of the transparency of white or nearly white translucent paper, tracing paper and other papers. GB/T 2679.1-93
Replaces GB2679.1--81
Note: The determination of the transparency of colored translucent paper can be carried out in accordance with the method specified in this standard, but it is limited to comparison between papers of the same color. 2 Reference standards
GB450 Paper and paperboard sample sampling
GB1543 Paper opacity determination method (paper backing) GB7973 Pulp, paper and paperboard diffuse reflection factor determination method (diffuse/vertical method) GB8940.1 Paper and paperboard whiteness determination method (45/0 directional reflection method) 3 Terminology
3.1 Reflection factor R
The ratio of the radiant flux reflected by an object to the radiant flux reflected by a completely reflecting diffuser under the same conditions, expressed as a percentage. 3.2 Reflection factor R.
Green light reflection factor when a single-layer sample is backed by a standard black board. 3.3 Reflection factor Rw
Green light reflection factor when a single-layer sample is backed by a standard white board. 3.4 Transparency of paper T
The degree of obviousness of the shadow of the covered object reflected by a single-layer paper sheet. The result calculated according to the formula specified in this standard is the transparency of the paper sheet.
4 Instruments
4.1 Reflection photometer
The spectral characteristics of the reflection photometer shall comply with the provisions of Appendix A of GB1543, and its geometric characteristics shall comply with the provisions of GB7973 or GB8940.1.
4.2 Standard white plate
The green light reflection factor of the standard white plate is (84±1)%. 4.3 Standard black tube
The green light reflection factor of the standard black tube is not more than 0.5%. Approved by the State Administration of Technical Supervision on August 7, 1993 252Www.bzxZ.net
Implemented on March 1, 1994
5 Sample preparation
5.1 Draw samples according to the provisions of GB450.
GB/T 2679.1-93
5.2 Cut no less than 10 100mm×100mm square test pieces from the drawn samples. One side of the test piece is the longitudinal direction of the paper. Each test piece is stacked up with the front side facing up, and a test piece is placed on the top and bottom of the paper stack to protect the test piece from contamination. 6 Instrument calibration
6.1 Operate according to the instrument manual to make the spectral power distribution of the instrument meet the requirements of 4.1. 6.2 After the instrument is preheated for the specified time, calibrate it with a standard black cylinder and a working standard white board respectively. 6.3 The calibration of the working standard white board shall be carried out in accordance with the provisions of Chapters 2, 3, and 4 of GB7973. 7 Measurement procedure
7.1 Take out the first test piece under the protective test piece from the sample stack, turn it upside down, and back it with a working standard white board so that the diagonal direction of the test piece is parallel to the front and back direction of the instrument, and test its reflection factor Rw. Then use the same method to turn the back of the test piece up and test its Rw. Test no less than three valid test pieces on the front and back sides in sequence.
7.2 Back the test piece with R measured with a standard black cylinder and test its reflection factor R according to the method in 7.1. 。 Test at least three valid test pieces on both sides in sequence.
8 Calculation
8.1 Calculate the arithmetic mean of the test results R and R. in 7.1 and 7.2 respectively. 8.2 Calculate the transparency T of the sample as follows, expressed as a percentage, rounded to one decimal place. R_R. × 100
T(%) =
Where, R. -
-The average value of the green light reflection factor when the single-layer sample is backed by a standard black tube, %; The average value of the green light reflection factor when the single-layer sample is backed by a standard white board, %. 9 Test report
The test report should include the following:
This standard number;
The mark and description of the sample;
The model of the reflectance photometer used;
The transparency value of the sample;
Any operation that deviates from this standard.
Additional Notes:
GB/T2679.1-93
This standard was proposed by the Ministry of Light Industry of the People's Republic of China. This standard is under the jurisdiction of the National Technical Committee for Paper Industry Standardization. This standard was drafted by the Paper Industry Scientific Research Institute of the Ministry of Light Industry. The main drafters of this standard are Liu Keqian, Wang Changtai, Du Jin and Meng Wei. This standard adopts the former Soviet Union national standard rOCT887472 "Paper: Determination of transparency and opacity" 254
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