GB/T 40278-2021 English PDF (GBT40278-2021)

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GB/T 40278-2021: Paper and board - Accelerated ageing (exposure to light)
GB/T 40278-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 85.010
Y 30
Paper and board - Accelerated ageing (exposure to
light)
(ISO 5630-7:2014, Paper and board - Accelerated ageing - Part 7:
Exposure to light, MOD)
ISSUED ON: MAY 21, 2021
IMPLEMENTED ON: DECEMBER 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 Principle ... 5 
4 Instruments ... 6 
5 Sample collection ... 6 
6 Sample processing ... 7 
7 Sample preparation ... 7 
8 Analysis steps ... 7 
9 Result calculation ... 8 
10 Test report ... 9 
Paper and board - Accelerated ageing (exposure to
light)
1 Scope
This Standard specifies the test method for accelerated ageing of paper and
board exposed to high light irradiance conditions, and predicts the effect of light
ageing process on paper stability under natural conditions by evaluating the
effect of ageing treatment on the optical properties of paper.
This Standard applies to all kinds of white or nearly white paper and board.
2 Normative references
The following documents are indispensable for the application of this document.
For dated references, only the dated version applies to this document. For
undated references, the latest edition (including all amendments) applies 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 10739, Paper, board and pulps - Standard atmosphere for conditioning
and testing (GB/T 10739-2002, eqv ISO 187:1990)
GB/T 21245, Paper and board - Determination of color (C/2°diffuse
reflectance method) (GB/T 21245-2007, ISO 5631:2000, IDT)
GB/T 40277, Paper, board and pulps - Measurement of diffuse blue
reflectance factor (ISO brightness) - Indoor daylight conditions (GB/T 40277-
2021, ISO 2470-1:2016, MOD)
3 Principle
Expose the samples to high light irradiance conditions for ageing treatment;
compare the changes in ISO brightness and CIE-b* values before and after the
ageing treatment of the samples, to measure the stability of the samples under
natural light conditions.
If the front and back sides of the sample cannot be distinguished, a mark shall
be made on the sample to ensure that the test surface of the sample is the
same side.
6 Sample processing
Take the sample out from the dark, and immediately perform temperature and
humidity treatment on the sample under the standard atmospheric conditions
that are specified in GB/T 10739.
7 Sample preparation
The preparation of samples shall be carried out under the standard atmospheric
conditions that are specified in Chapter 6. Cut two stacks of samples; the size
of the sample shall meet the requirements of optical performance testing. One
stack is used as the test sample and the other stack is used as the backing
paper of the test sample. The number of test samples is not less than 10 pieces.
8 Analysis steps
Under the standard atmospheric conditions that are specified in GB/T 10739,
test the ISO brightness and CIE-b* value of the front side of the sample
according to the requirements of GB/T 40277 and GB/T 21245 respectively. Be
careful not to use the backing paper as the test sample during the test. Use an
appropriate method to mark the test area of the sample, so as to ensure that
the test is still performed in the same area after the sample is aged. Keep the
backing paper for testing the optical properties of the sample after ageing.
After the test is completed, immediately put the sample into the light chamber
(4.2), so that the surface of each sample is exposed to the same light irradiance
(4.1). When placing the sample, be careful not to make it touch the inner wall
of the light chamber. When placing and processing samples, the light chamber
shall be under the standard atmospheric conditions that are specified in GB/T
10739.
After placing the sample in the light chamber, immediately expose the sample
to the specified light irradiance for (120.0±0.5) h; ensure that the surface
temperature of each sample is between 22 °C ~ 26 °C. Under the guarantee of
the ratio of total irradiance to ultraviolet light content, an irradiance lower than
the irradiance that is specified in 4.1 can be used, in which case the exposure
time needs to be extended.
During the ageing process, the light chamber shall not be opened to put in or
take out the sample.