Interpreting ISO 2469: A Global Universal Standard for Diffuse Reflectance Properties of Pulps, Papers and Boards

In the papermaking, printing and related industrial chains, the optical properties of pulps, papers and boards directly determine product quality, application adaptability and market competitiveness. As a core optical index, the uniformity and accuracy of diffuse reflectance measurement are crucial. 国际标准化组织 2469, a special standard developed by the International Organization for Standardization (国际标准化组织), provides a unified paradigm for the measurement of diffuse reflectance related to such products worldwide, and is an important basis for industry quality control, trade and technological research and development. This article will comprehensively interpret ISO 2469 from the aspects of standard foundation, development history, core content, practical applications and important significance, helping industry practitioners deeply understand its value and application points.

我. Basic Cognition of ISO 2469 标准

1.1 Core Positioning of the Standard
国际标准化组织 2469 is fully titled “纸, board and pulps — Measurement of diffuse radiance factor (diffuse reflectance factor)”. It belongs to the fields of Pulps (85.040) and Paper and Board (85.060) in the International Classification for Standards (ICS), and corresponds to Paper (Y32) in the Chinese Standard Classification. The core goal of this standard is to standardize the measurement methods of diffuse radiance factor for various pulps, papers and boards, ensure the comparability and reliability of measurement results between different laboratories, enterprises and countries, and eliminate technical barriers for industry quality control and global trade.

1.2 Definition of Core Terms
To understand ISO 2469, it is first necessary to clarify the key terms defined by it, which is the basis for the implementation of the standard. The core terms include:
•Radiance factor: The ratio of the radiance of a surface element in a specific direction to that of a perfect diffuse reflector, which is a basic parameter for measuring the reflectivity of materials.
•Diffuse radiance factor: The ratio of the radiance of a material under diffuse illumination and normal detection conditions to that of a perfect diffuse reflector, which is also the core index focused on by ISO 2469.
•Intrinsic diffuse radiance factor: The diffuse radiance factor of a layer or pad of material thick enough to be opaque, which can avoid the interference of material thickness on measurement results and better reflect the inherent optical properties of the material itself.

二. Development History of ISO 2469 标准

Since its release, 国际标准化组织 2469 has always kept pace with the technological development and market demand of the papermaking industry, and has undergone many revisions and improvements to gradually improve measurement accuracy and applicability. The evolution of its successive versions is as follows:
1.在 1977, 国际标准化组织 2469:1977 was released for the first time, establishing the basic framework for the determination of diffuse reflectance factor of paper, board and pulp, and providing the industry with the first unified measurement standard.
2.在 1994, 国际标准化组织 2469:1994 was released, optimizing the measurement method and clarifying the basic requirements for test equipment. 同时, 技术修正 1 (国际标准化组织 2469:1994/Cor 1:1998) was released to correct detailed problems in practice.
3.在 2007, 国际标准化组织 2469:2007 was released, further refining the measurement process, clarifying the specific requirements for sample handling and environmental control, and improving the stability of measurement results.
4.在 2014, 国际标准化组织 2469:2014 was released, referencing more relevant international standards (such as CIE lighting standards and other papermaking industry measurement standards), improving the measurement requirements for fluorescent whitening agent materials, and clarifying the specific specifications for instrument calibration.
5.在 2024, 国际标准化组织 2469:2024 was officially released. As the latest version, it further optimizes the measurement paradigm, adapts to the development of digital and intelligent measurement equipment, strengthens the connection with the global metrological system, and becomes an important foundation for the industry to move towards optical precision and quality digitalization.
此外, this standard is widely adopted worldwide. Many countries have formulated their own corresponding national standards based on ISO 2469, such as the British BS ISO 2469 series, the Korean KS M ISO 2469 series, and the French NF ISO 2469:2014, forming a global unified measurement system.

III. Analysis of the Core Content of ISO 2469

The core content of ISO 2469 revolves around “the uniformity and accuracy of measurement”, covering measurement principles, 仪器要求, sample handling, calibration procedures, result expression and other aspects. It is applicable to all types of pulps, papers and boards, including materials containing fluorescent whitening agents.

3.1 Measurement Principle
The standard adopts the core principle of diffuse illumination and normal detection, 那是, simulating a specific light source (such as CIE illuminant C, D65, ETC。) to diffusely irradiate the sample, detecting the reflected radiance of the sample in the vertical direction, and then comparing it with the radiance of a perfect diffuse reflector to calculate the diffuse radiance factor. For materials containing fluorescent whitening agents, it is necessary to adjust the ultraviolet content of the instrument illumination to be consistent with the fluorescent reference standard of the selected CIE light source to ensure the accuracy of measurement results.
同时, the standard specifies two key measurement geometries: d/0° (diffuse illumination, 0° viewing angle) and 0°/d (0° illumination, diffuse viewing angle), and precisely defines the integrating sphere geometry to adapt to the measurement needs of different types of samples.

3.2 Instrument Requirements
国际标准化组织 2469 puts forward clear requirements for the technical parameters of measurement instruments (mainly reflectometers and spectrophotometers), the core of which includes:
•Spectral characteristics: It shall meet specific wavelength requirements. 例如, when measuring ISO brightness, the dominant wavelength is 457 nm and the half-wave width is 44 nm to ensure that the spectral response matches human vision.
•Geometric conditions: It shall meet the d/0° or 0°/d geometric requirements. The diameter of the integrating sphere and the diameter of the test hole shall comply with the standard provisions (such as the integrating sphere diameter of 150mm and the test hole diameter of 32mm), and a gloss absorber shall be provided to eliminate the specular reflection light of the test sample.
•Calibration requirements: Instruments shall be calibrated regularly. Calibration shall be based on relevant standards such as ISO 4094, and first-class, second-class and third-class international reference standards (IR1, IR2, IR3) shall be used for quantity transmission to ensure measurement accuracy.
例如, equipment such as Datacolor Elrepho 1000 spectrophotometer and WSB-3A intelligent digital whiteness meter all meet the instrument requirements of ISO 2469 and can be used for the measurement work specified by the standard.

3.3 Sample Handling and Test Procedures
The standard puts forward strict requirements for the sampling, preparation and handling of samples to avoid the interference of the samples themselves on the measurement results. The core procedures are as follows:
•Sample sampling: Representative samples shall be taken in accordance with relevant standards (such as GB/T 450, 国标/T 740), avoiding watermarks, dust and obvious paper defects.
•Sample preparation: Cut the sample into the specified size (例如 75 毫米× 150 毫米) to form a sample stack. The number of layers shall be thick enough to reach an opaque state (to ensure the accuracy of the measurement of the intrinsic diffuse radiance factor). Protective paper sheets shall be attached to the top and bottom of the sample stack to avoid contamination.
•Environmental control: Samples shall avoid high-temperature and high-humidity pretreatment, and can be subjected to temperature and humidity treatment as required (such as specified in GB/T 10739) to ensure a stable test environment.
•Test process: After the instrument is preheated, calibrate it with non-fluorescent reference standards and fluorescent reference standards, then test the top sample of the sample stack in turn, record no less than 10 test results, and calculate the average value and standard deviation.

3.4 Calibration and Reference Standards
Calibration is the key to ensuring the accuracy of measurement results. 国际标准化组织 2469 clarifies a three-level reference standard system. The purpose and calibration requirements of each level of standard are as follows:
•First-class International Reference Standard (IR1): Calibrated by international standardization laboratories, it serves as the benchmark for quantity transmission.
•Second-class International Reference Standard (IR2): Calibrated by standardization laboratories based on IR1, it is divided into non-fluorescent and fluorescent types, which are used to calibrate the photometric scale of reference instruments in authorized laboratories and adjust the ultraviolet content of instruments respectively.
•Third-class International Reference Standard (IR3): Calibrated by authorized laboratories based on IR2, it is also divided into non-fluorescent and fluorescent types, which are used to calibrate instruments in test laboratories and adjust the ultraviolet level of sample irradiation.
此外, the standard also specifies the calibration requirements for working standards. Working standards shall be calibrated through IR3 and used for daily instrument calibration and testing to ensure measurement consistency.

3.5 Result Expression and Abnormal Value Handling
Measurement results are expressed as diffuse radiance factor (百分比), which shall be accurate to the specified precision (such as ISO brightness accurate to 0.5%). 同时, parameters such as average value and standard deviation shall be reported. If the measurement difference between the two sides of the sample exceeds the specified range (例如 0.5%), the results of the two sides shall be reported separately; if the difference is within the allowable range, the average value of the two sides can be reported.
For abnormal values, the standard specifies handling methods to ensure the reliability of measurement results. 同时, it is required to indicate any deviation from the standard in the test report, as well as factors that may affect the results (such as instrument type, environmental conditions, ETC。).

IV. Practical Application Scenarios of ISO 2469

As a basic measurement standard in the papermaking industry, 国际标准化组织 2469 has application scenarios throughout the entire industrial chain of pulp production, paper manufacturing, printing and processing, quality inspection, and extends to related supporting fields.

4.1 Quality Control in Papermaking Enterprises
For pulp, paper and board production enterprises, 国际标准化组织 2469 is the core basis for quality control. By following the standard to measure the diffuse reflectance properties of products, enterprises can accurately control key indicators such as product whiteness and opacity, ensure the consistency of products from different batches, and avoid affecting market reputation due to quality fluctuations. 例如, when producing cultural paper, it is necessary to control the whiteness of the paper through standard measurement to ensure the printing effect; when producing packaging

our product GA-5011 Paper Whiteness Tester meets this standard.

GA-5011 Paper Whiteness Tester
概述:
白色/亮度测试仪是确定白度, 黄色, 物体的颜色和颜色差异, 但也可以确定纸张的不透明度, 透明度, 光散射系数, 光吸收系数和墨水吸收值。, 印刷, 陶瓷, 化学工业, 纺织印刷和染色, 建筑材料, 粮食, 盐和其他行业.

设备功能:
1.测量对象的反射颜色和颜色差异, 可以显示或打印: 弥漫反射因子Rx, RY, RZ, 刺激值y10, x10, Z10, 色度坐标x10, Y10, Z10;轻度l *, A * 色度, 乙 *, 色度c * ab, 色调角h * ab, 主要波长lambda d, 激发纯度, 或δe * AB颜色, 亮度差δl *, 色度差δAB, 音调δH C * * ab, 猎人系统l, a和b.
2.ISO亮度 (蓝光白度R457) 和z白度 (RZ) 可以测量以测量通过在荧光美白样品中发射荧光物质产生的荧光白度.
3.CIE白度 (Gantz Whitenes W10和Color TW10) 被测量.
4.测量陶瓷的白度.
5.测量建筑材料和非金属矿物的白度.
6.测量猎人白人.
7.测量黄色.
8.测试样品的不透明度
9.测量样品的透明度T
10.测量样品的光散射系数S
11.测量样品的光吸收系数A.
12.测量墨水吸收值.

Test standards：
国际标准化组织 2469 纸, Board and Pulp — Determination of Diffuse reflectance Factors
国际标准化组织 2470 Paper and Board — Determination of Whiteness (弥漫/垂直方法)
国际标准化组织 2471 Paper and Board — Determination of Opacity (纸衬) — Diffuse reflectance Method
国际标准化组织 9416 “Determination of Light Scattering and Light Absorption Coefficients of Paper” (Kubelka-Munk)
国际标准化组织 11475 “Determination of CIE Whiteness for Paper and Cardboard, D65/10 (户外日光)”
国标/T 7973 确定纸张的分散反射因子, 木板和纸浆 (弥漫/垂直方法)
国标/T 7974 “Determination of Brightness (白色) 纸, Board and Pulp”
国标/T 7975 “Determination of Color of Paper and Board (扩散反射法)”
国标/T 24288 — Determination of Main Wavelength and Excitation Purity of Paper and Board — D65/10 Diffuse reflectance Method
国标/T 10339 “Determination of Light Scattering and Light Absorption Coefficients of Paper, Board and Pulp”
国标/T 8424.2 纺织色粘度测试相对白度的工具评估方法
国标/T 13173.14 “Test Method for Surfactant Detergents — Determination of Whiteness of Powder Detergents”
国标/T 8424.1 确定纺织品颜色牢度测试表面颜色的一般原则
Paper and Board — Determination of CIE Whiteness, D65/10 (户外日光)
国标/T 1543 “Determination of Opacity of Paper and Board (纸衬)”
国标/T 6688 “Instrumental Method for the Determination of Relative Strength and Chromatic Aberration of Dyes”
国标/T 13025.2 盐业的一般测试方法, 确定白色
国标/T 2913 塑料白度的测试方法
国标/T 5950 建筑材料和非金属矿物产品的白度的测量方法
国标/T 3979 对象颜色的测量方法
国标/T 8424.3 计算纺织色固定测试的色差差异
国标/T 2679 – Determination of Paper Transparency
国标/T 9338 确定荧光照亮剂相对白度的仪器方法
国标/T 11186 涂层膜颜色的测量方法
国标/T 9984.5 “Test Method for Sodium tripolyphosphate for Industry — Determination of Whiteness”
国标/T 22427.6 淀粉白度的确定
国标/T 13835.7 测试方法的兔头发纤维的白度
国标/T 12911 “Determination of Ink Absorbability of Paper and Cardboard”
国标/T 4739 “Method for Determination of Colorimetry for Ceramic Pigments for Daily Use”
国标/T 11942 彩色建筑材料的色度的测量方法
QB/T。 2789 化妆品的通用测试方法，颜色tristimulus价值和色差△e*确定
QB/T。 1503 “Method for Determination of Whiteness of Ceramics for Daily Use”
塑料黄色指数HG/T的测试方法 3862
Fz-t50013 test Methods for Whiteness of Cellulose Chemical Fibers – Blue Ray Diffuse Reflection Factor Method

主要性能参数
1. 该仪器具有新颖的外观和紧凑的结构, 高级电路设计有效地确保了测量数据的准确性和稳定性.
2. 该仪器模拟D65照明。 1964 补充色度系统和CIE 1976 (l* a * 乙 *) 使用色彩空间色差公式.
3. 该仪器采用D/O照明来观察几何条件。弥漫性球的直径为150mm, 测试孔的直径为30mm, 并提供了吸光器以消除样品的镜面反射的影响.
4. 采用具有大屏幕和高像素的LCD模块以中文显示测量和统计结果，并提示操作步骤. 友好的人机接口使乐器的操作简单便捷
5. 该仪器添加打印机并采用导入的热打印机芯, 无需使用墨水和缎带, 工作时没有噪音, 快速打印速度和其他特征
6. 该仪器配备了标准RS232接口, 可以与微型计算机软件进行通信
7. 该仪器受电源关闭的保护, 电源关闭后不会丢失校准数据
8. 可以存储 9 参考样本.

技术规格