Liaoning Xinda Talc Group Co., Ltd. - Yang Yongli

1、 Introduction

（1） Application value of talc powder: As an important industrial mineral filler, talc powder is widely used in fields such as plastics, coatings, papermaking, ceramics, etc. Its quality directly affects the performance of end products. （2） The importance of whiteness: Whiteness is one of the key indicators for measuring the quality of talc powder, which directly affects the appearance performance and application value of products. Therefore, the research on whiteness of talc powder by Liaoning Xinda Talc Group R&D Center has important practical significance. Research has shown that the automotive and home appliance plastic industries are concerned about the DMP whiteness of talc powder; The papermaking and interior and exterior wall coating industries pay attention to the dryness and whiteness of talcum powder; The ceramic industry pays attention to the whiteness of talc powder after firing; It can be seen that different industries have different concerns about whiteness.

2、 Common whiteness evaluation systems and their application in talc powder:

（1） Blue Brightness - Definition: Using blue light as the light source, the whiteness is characterized by measuring the reflectivity of talc powder to blue light. The wavelength of blue light is usually around 457nm. The ZB-B whiteness meter used by the R&D center of Liaoning Xinda talc group is blue whiteness. Its characteristics are relatively simple to operate and widely used in industries such as papermaking and textiles, which can better reflect the whiteness performance of talc powder under blue light irradiation.

（2） Hunter Whiteness - Definition: Based on the Hunter Lab color space, it is calculated by considering the brightness (L value) and color cast (a value, b value) of talc powder. The formula is: Hunter Whiteness=100- [(100-L) ²+a ²+b ²] ¹/².

Its characteristics include not only focusing on brightness, but also taking into account the color deviation of talc powder (such as yellowish, bluish, etc.), which can comprehensively evaluate whiteness. It is widely used in fields such as coatings and plastics that require high color requirements.

（3） Ganz Whiteness - Definition: Based on the Ganz color system, taking into account the sensitivity of the human eye to different wavelengths of light, the whiteness value is obtained through a complex computational model. Its characteristics: It is more in line with the human eye's perception of color, and the evaluation results are more objective. It has certain applications in high-end cosmetics, precision instruments and other fields.

3、 Factors affecting the whiteness of talc powder

（1） Mineral characteristics: Due to the presence of colored impurities such as iron and manganese in talc ore, the whiteness of the product will be reduced;

（2） Crystal structure: The integrity of talc crystals affects the light reflectivity; Talc often coexists with quartz (refractive index 1.54-1.55), calcite (1.48-1.66), chlorite (1.57-1.62), etc. The presence of impurity minerals can cause the overall refractive index to deviate from the pure talc range, thereby changing the whiteness performance;

（3） Processing technology: Grinding fineness. Coarse particles may cause uneven dispersion of light and affect the stability of whiteness. Liaoning Xinda Talc Group has advanced 6 sets of vertical grinding and grading systems, which can effectively solve the problem of coarse particles in products; In addition, Xinda Group also has an automatic mixing system to maintain the stability of product ratio, thereby ensuring the stability of product whiteness;

4、 Foreign talc powder whiteness standards: Different countries have developed relevant standards based on their own industry needs, and the following are some of the main standards:

（1） The United States: ASTM standards involve the determination of the whiteness of talc powder, ASTM D1535， Measure reflectance using a specific spectrophotometer, referencing indicators such as blue light whiteness, and evaluate in conjunction with color coordinates.

（2） EU: The EN standard has clear regulations on the whiteness of talc powder, EN 120， Based on the CIE (International Commission on Illumination) color system, taking into account brightness and color cast, there are similarities with the evaluation approach of Hunter whiteness.

（3） Japan: In JIS standard JIS M 3801, the determination of talc whiteness is mainly based on blue light reflectance, and corresponding measurement conditions and instrument requirements are specified, which is applicable to industrial production and trade in Japan.

5、 Summary

There are various systems for evaluating the whiteness of talc powder, such as blue light whiteness, Hunter whiteness, Ganz whiteness, etc., each with its own characteristics and applicable fields. The whiteness standards for talcum powder abroad are mostly based on internationally recognized color systems, combined with their own industry characteristics, aiming to standardize the quality evaluation of talcum powder and ensure the stability of product application. In practical applications, it is necessary to select appropriate whiteness evaluation methods and corresponding standards based on specific usage scenarios and target markets.

In the future, it is necessary to further optimize the whiteness evaluation criteria to make them more in line with practical application needs; At the same time, promote the coordination and unification of domestic and international standards, and assist in the international trade and quality improvement of talc powder.