GB/T 7974-2013 in English

《GB/T 7974-2013纸、纸板和纸浆 蓝光漫反射因数D65亮度的测定（漫射/垂直法，室外日光条件）》由TC141（全国造纸工业标准化技术委员会）归口，主管部门为中国轻工业联合会。
本标准规定了纸、纸板和纸浆D65亮度的测定方法。
本标准适用于白色和接近白色的纸、纸板和纸浆,也适用于含有荧光增白剂的纸、纸板和纸浆。
测量含有荧光增白剂的试样时,应使用荧光参比标准将仪器的紫外辐射能量水平调整至与CIE标准照明D65一致的情况下才能进行测量。
由于本标准采用的D65光源激发的荧光约为ISO 2470-1-2009 中C光源的2倍,因此本标准更适用于测量荧光对提高亮度的贡献。

1 Scope

This standard specifies a method for measuring the D65 brightness of pulps, papers and boards.

This standard is applicable to white and near-white papers, boards and pulps, particularly those exhibiting fluorescence which promotes the appearance of whiteness. If the test piece with fluorescent whitening agent is measured, the measurement can only be made in an instrument in which the ultraviolet energy level of the illumination has been adjusted to correspond to the CIE standard illuminant D65 using a fluorescent reference standard.

The D65 light source employed in this standard excites almost twice as much fluorescence as the light source in ISO 2470-1: 2009. Consequently, this standard is better suited for measuring the fluorescent contribution to the brightness.

Notes: The property called ISO brightness is measured with an instrument adjusted to a much lower UV content than that specified in this standard.D65 brightness should not be confused with ISO brightness which closely approximates the brightness of papers viewed under indoor conditions. The measurement of ISO brightness is described in ISO 2470-1: 2009.

2 Normative references

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.

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 740 Pulps - Sampling for testing (GB/T 740-2003, ISO 7213: 1991, IDT)
GB/T 7973 Paper, board and pulps - Measurement of diffuse reflectance factor (Diff/ Geometry) (GB/T 7973-2003, ISO 2469: 1994, NEQ)
GB/T 8940.2 Pulp - Preparation of laboratory sheets for the measurement of brightness (GB/T 8940.2-2002, ISO 3688: 1999, EQV)
GB/T 10739 Paper board and pulp - Standard atmosphere for conditioning and testing (GB/T 10739-2002, ISO 187: 1990, EQV)
GB/T 22880-2008 Paper and board - Determination of CIE whiteness, D65/10° (outdoor daylight) (GB/T 22880-2008, ISO 11475: 2004, MOD)

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

3.1

diffuse radiance factor, R

ratio of the radiation reflected and emitted from a body to that reflected from the perfect reflecting diffuser under the same conditions of diffuse illumination and normal detection. The ratio is often expressed as a percentage

Note: The diffuse radiance factor is influenced by the backing if the body is translucent.

3.2

intrinsic radiance factor, R∞

radiance factor 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 sheets results in no change in the measured results

3.3

D65 brightness, R457，D65

Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Instruments
6 Sampling
7. Preparation of test pieces
8 Instrument calibration
9 Procedure
10 Expression of results
11 Precision
12 Test report
Annex A (Normative) Spectral characteristics of instruments for measuring D65 brightness