Titanium Dioxide Pigment Porous Dense Coating Optical Crowding
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Solution Overview
Problem
Inorganic oxide pigments like titanium dioxide tend to flocculate or agglomerate in base media, leading to reduced opacity, brightness, and light scattering efficiency at high concentrations, and existing techniques to prevent this are inefficient and costly, especially in terms of handling and processing.
Innovation Solution
A coated inorganic oxide pigment is developed with a combination of a porous and dense inorganic coating, specifically using alumina and silica, applied in situ in an aqueous slurry to enhance light scattering efficiency and processing characteristics, allowing for higher concentrations without optical crowding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high concentration of pigment is incorporated into base medium, then opacity and tint strength are improved, but light scattering efficiency decreases due to optical crowding
Solution Approach 1:
The patent applies porous silica coating on pigment particles to create a hierarchical porous structure. The porous nature of the coating increases the light scattering cross-section of individual particles while maintaining particle separation, thereby improving light scattering efficiency even at high pigment concentrations and reducing optical crowding effects.
Solution Approach 2:
The patent creates a composite structure by coating pigment particles with a combination of porous silica and dense alumina or silica. This composite coating system provides both optical benefits (enhanced light scattering) and processing benefits (improved bulk density and handling), allowing high pigment concentration without optical crowding.
2Reliability
If pigment particles are coated with inorganic compounds to prevent flocculation, then light stability and brightness are improved, but handling and processing difficulty increases due to low bulk density
Solution Approach 1:
The patent uses a composite coating system combining porous silica with dense alumina or dense silica. The dense component provides high bulk density for easy handling and processing, while the porous component maintains optical properties and prevents flocculation, thus resolving the contradiction between reliability and ease of operation.
Solution Approach 2:
The patent applies different coating materials with different properties to the pigment particle surface. The porous silica provides local optical functionality (light scattering, anti-flocculation) while the dense alumina or silica provides local mechanical functionality (bulk density, handling), allowing each region of the coating to optimize for its specific function.
3Illumination intensity
If spacer particles are used to space pigment particles apart, then optical crowding is reduced, but dispersion difficulty increases and titanium dioxide concentration decreases
Solution Approach 1:
The patent extracts the spacing function from separate spacer particles and integrates it into the coating structure itself. The porous silica coating forms an inherent spacer layer between pigment particles, eliminating the need for additional spacer particles and simplifying the dispersion process while maintaining light scattering efficiency.
4Ease of operation
If pigment is supplied as slurry to overcome low bulk density, then processing is facilitated, but application complexity increases in some applications
Solution Approach 1:
The composite coating of porous silica and dense alumina/silica provides inherently high bulk density to the pigment powder, allowing it to be supplied and processed as a dry powder rather than requiring slurry form. This eliminates the complexity associated with slurry application while maintaining processing ease through the improved bulk density.
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 coated pigment maintains high light scattering efficiency and tint strength even at high concentrations, with improved bulk density and processing ease, making it suitable for use in polymers as a whiteners or opacifiers.
Implementation Method 1
the light scattering efficiency or tint strength of the pigment can substantially decrease... the light scattering cross-section of an inorganic oxide pigment particle is significantly greater than the actual cross-section (area) of the pigment particle
Implementation Method 2
the pigment particles have been coated with various inorganic compounds that function to modify the surface charges of the particles
Data Source
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AI summary
The invention provides a coated inorganic oxide pigment. The inventive coated inorganic oxide pigment comprises an inorganic oxide base pigment, a porous inorganic coating formed on the base pigment, and a dense inorganic coating formed on the base pigment. The porous inorganic coating and dense inorganic coating each consist essentially of a material selected from the group consisting of silica and alumina. In another aspect, the invention provides a method of manufacturing a coated inorganic oxide pigment. In yet another aspect, the invention provides a polymer composition comprising a base polymer, and a coated inorganic oxide pigment admixed with the base polymer.