Core-Shell Inorganic Oxide Particles for Coating Stability

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Solution Overview

Problem

Titanium oxide fine particles with small diameters used in coating solutions for optical lenses suffer from degradation in weather resistance and light resistance, leading to issues like film separation, yellowing, or bluing.

Innovation Solution

A dispersion liquid containing core-shell type inorganic oxide particles, where titanium-containing core particles are treated with a hydrate or oxide of zirconium, tin, niobium, barium, lanthanum, strontium, cerium, or lithium, and then coated with a composite oxide of silicon and aluminum, zirconium, or antimony, enhancing their surface properties and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If titanium oxide fine particles with small particle diameter are used in coating solutions, then transparency of the coating film is improved, but weather resistance and light resistance are degraded

Engineering Contradiction:
ImprovetransparencyVSAvoidweather resistance and light resistance
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent applies composite materials by creating core-shell type inorganic oxide particles where a titanium-containing core is surrounded by a protective shell layer. The core provides high refractive index for transparency, while the shell layer composed of silicon oxide and zirconium oxide protects against weather and light degradation, resolving the contradiction between transparency and reliability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent uses nested structure by placing one material inside another - the titanium-containing metal oxide core is nested within the silica-zirconia shell layer. This nested configuration allows the inner core to provide optical properties while the outer shell provides protective functions, simultaneously achieving transparency and weather/light resistance.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Illumination intensity

If titanium oxide fine particles with small particle diameter are used in coating solutions, then transparency of the coating film is improved, but film separation occurs due to high activity

Engineering Contradiction:
ImprovetransparencyVSAvoidfilm stability
Core Design Contradiction:
Illumination intensityVSStability of the object's composition

Solution Approach 1:

The patent creates composite core-shell particles where the titanium-containing core is combined with a stabilizing shell layer of silicon oxide and zirconium oxide. This composite structure reduces the high surface activity of small titanium oxide particles while maintaining their transparency benefits, preventing film separation.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The shell layer acts as an intermediary between the highly active titanium oxide core and the external environment. This intermediate layer moderates the surface activity of the core particles, reducing their tendency to cause film separation while allowing the core to maintain its optical properties.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 treated particles exhibit improved dispersion stability, light resistance, and weather resistance, preventing film degradation and maintaining transparency and adhesion, while also enhancing the refractive index of the coating film.

Implementation Method 1

treating the surfaces of (a) fine particles of titanium-containing metal oxide serving as core particles with a hydrate and/or an oxide of at least one metal element selected from zirconium, tin, niobium, barium, lanthanum, strontium, cerium, and lithium to provide surface-treated particles

Methodology Applied
Scientific EffectSurface treatment with hydrate/oxide: Deposition (physical)

Implementation Method 2

covering the surfaces of the surface-treated particles with a composite oxide of silicon and at least one metal element selected from aluminum, zirconium, and antimony

Methodology Applied
Scientific EffectCoating with composite oxide: Deposition (physical)

Implementation Method 3

A dispersion liquid according to the present invention contains fine particles of core-shell type inorganic oxide

Methodology Applied
Scientific EffectDispersion: Dispersion (of waves)

Data Source

PatentUS9834450B2Dispersion liquid of fine particles of core-shell type inorganic oxide, method for producing the dispersion liquid, and coating composition containing the dispersion liquid
Publication Date: 2017.12.05 JGC CATALYSTS & CHEMICALS LTD

AI summary

A dispersion liquid contains fine particles of core-shell type inorganic oxide that have high dispersion stability and transparency and allow for excellent light resistance and weather resistance by being mixed in a coating film. The fine particles are produced by treating the surfaces of (a) fine particles of titanium-containing metal oxide serving as core particles with a hydrate and/or an oxide of a metal element such as zirconium to provide surface-treated particles or fine particles of titanium-containing metal oxide having (b) an intermediate layer and by covering the surfaces of the surface-treated particles to form (c) a shell layer with a composite oxide of silicon and at least one metal element selected from aluminum, zirconium, and antimony.