Luster Pigment Particle Size Control
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Solution Overview
Problem
Conventional luster pigments with flaky particles exhibit a wide range of particle size distribution, leading to issues such as decreased lustrous appearance, filter clogging, and detection of foreign substances when used in cosmetics and coatings.
Innovation Solution
Flaky particles with a controlled particle size distribution, where D90/D10 is between 2.0 and 3.0, D10 is between 4.7 μm and 25 μm, and a maximum particle diameter of 90 μm or less, are used, along with a metallic or metallic oxide layer on the particles, to achieve a balanced lustrous and particulate appearance while preventing filter clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flaky particles with wide particle size distribution are used as substrate for luster pigment, then the pigment can be manufactured easily, but the lustrous appearance decreases and fine particles cause smooth flat appearance without particulate appearance
Solution Approach 1:
The patent applies parameter changes by strictly controlling the particle size distribution parameters (D10, D50, D90 values and their ratios) of flaky particles used as substrate. This transforms the manufacturing approach from using conventional wide-distribution particles to using particles with specifically controlled size parameters, thereby achieving both good lustrous appearance and ease of manufacture
Solution Approach 2:
The patent applies local quality by differentiating particle size requirements for different portions of the particle distribution. Specifically, it controls the fine particle content (D10) separately from the coarse particle content (D90), optimizing each portion's contribution to the overall appearance. This ensures that fine particles do not dominate to cause smooth appearance while coarse particles do not cause foreign substance detection
2Ease of manufacture
If flaky particles with high content of coarse particles are used in luster pigment, then the pigment can be manufactured easily, but filter clogging occurs during coating composition circulation
Solution Approach 1:
The patent applies parameter changes by setting specific upper limit values for particle size distribution parameters, particularly controlling D90 to be 8.0 times or less than D10 and D50 to be 5.0 times or less than D10. This parameter control effectively limits coarse particle content while maintaining ease of manufacture, preventing filter clogging during coating composition circulation
3Ease of manufacture
If flaky particles with high content of fine particles are used in luster pigment, then the pigment can be manufactured easily, but the lustrous appearance decreases and smooth flat appearance is obtained
Solution Approach 1:
The patent applies parameter changes by setting a lower limit for D10 (the 10th percentile particle diameter) to ensure sufficient fine particle presence for manufacturability while simultaneously setting upper limits on the ratios D90/D10 and D50/D10 to prevent fine particles from dominating. This balanced parameter control maintains ease of manufacture while ensuring good lustrous and particulate appearance
4Adaptability or versatility
If conventional luster pigment with wide particle size distribution is used, then the pigment can be applied broadly, but foreign substances are detected in coating and reliability decreases
Solution Approach 1:
The patent applies parameter changes by establishing specific ranges for particle size distribution parameters (D10, D50, D90 absolute values and their relative ratios). These parameter specifications ensure that particles fall within an optimal size range that prevents foreign substance detection while maintaining broad adaptability for various cosmetic and coating applications
Solution Approach 2:
The patent replaces the conventional approach of relying on post-manufacturing filtration or sorting with a preventive approach that controls particle size distribution at the manufacturing stage. By substituting mechanical filtration systems with parameter-controlled particle selection, the patent improves reliability by preventing foreign substance issues before they occur
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The controlled particle size distribution and coating of flaky particles result in a highly lustrous and particulate appearance in cosmetics and coatings, while minimizing filter clogging and detection of foreign substances.
Implementation Method 1
The luster pigments employing the flaky particles as described above (hereinafter, these luster pigments simply may be referred to as pigments) reflect light on their smooth surfaces and thus exhibit a satisfactory lustrous appearance.
Implementation Method 2
The flaky particles with a controlled particle size distribution, where D90/D10 is between 2.0 and 3.0, D10 is between 4.7 μm and 25 μm, and a maximum particle diameter of 90 μm or less, are used, along with a metallic or metallic oxide layer on the particles, to achieve a balanced lustrous and particulate appearance
Data Source
AI summary
Flaky particles of the present invention have a particle size distribution in which a value of D90/D10 is at least 2.0 but not more than 3.0, a value of D10 is at least 4.7 μm but not more than 25 μm, and a maximum particle diameter is 90 μm or less, where D10 is defined as a particle diameter at which a cumulative volume of particles reaches 10% when counted from the smaller side, and D90 is defined as a particle diameter at which a cumulative volume of particles reaches 90% when counted from the smaller side. A luster pigment of the present invention contains flaky particles and at least one selected from a metallic layer and a metallic oxide layer that are formed on at least a part of the surface of each of the flaky particles. The luster pigment has a particle size distribution in which a value of D90/D10 is at least 2.0 but not more than 3.0, a value of D10 is at least 4.7 μm but not more than 25 μm, and a maximum particle diameter is 90 μm or less, where D10 is defined as a particle diameter at which a cumulative volume of particles reaches 10% when counted from the smaller side, and D90 is defined as a particle diameter at which a cumulative volume of particles reaches 90% when counted from the smaller side.