Composite Tungsten Oxide Particles for Clear Near-Infrared Shielding

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Solution Overview

Problem

Existing near-infrared shielding materials suffer from issues such as color darkening due to visible light absorption, reflective glare, and inadequate weather resistance, limiting their application and effectiveness.

Innovation Solution

Development of near-infrared absorbing material particles composed of composite tungsten oxide particles (M x W y O z ) with specific x/y and z/y ratios, particle sizes between 10 nm to 100 nm, and hexagonal, tetragonal, or cubic crystal structures, coated with Si, Ti, or Zr compounds for enhanced weather resistance and reduced visible light scattering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If black fine powder (carbon black, titanium black, organic pigments) is used for near-infrared shielding, then near-infrared absorption is improved, but visible light absorption increases causing color darkening

Engineering Contradiction:
Improvenear-infrared absorptionVSAvoidvisible light transmission
Core Design Contradiction:
Object-affected harmful factorsVSIllumination intensity

Solution Approach 1:

The patent applies local quality by using particles with specific optical properties that selectively absorb near-infrared radiation while maintaining visible light transmission. The spherical particles with controlled size distribution (0.1-10 μm) and refractive index create localized optical effects that target specific wavelength ranges, allowing near-infrared shielding without compromising visible light passage.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining spherical particles with specific optical characteristics into a coating composition that integrates multiple functional properties. The particles are dispersed in a transparent binder matrix, creating a composite structure that achieves near-infrared absorption while maintaining overall transparency and avoiding color darkening.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If metal deposition film is applied for infrared reflection, then infrared shielding is improved, but reflective glare and half-mirror appearance occur

Engineering Contradiction:
Improveinfrared shieldingVSAvoidreflective glare
Core Design Contradiction:
Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent inverts the conventional approach by using absorption rather than reflection for infrared shielding. Instead of applying metal films that reflect infrared radiation and create glare, the invention uses spherical particles that absorb near-infrared radiation through their optical properties, eliminating the reflective glare problem while maintaining shielding effectiveness.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent applies color changes principle by selecting particles with specific optical absorption characteristics that target near-infrared wavelengths while being transparent to visible light. This selective absorption creates no perceptible color change in the visible range, avoiding the darkening and glare issues associated with traditional approaches.

Inventive Principle:
Principle #32Color changes

3Object-affected harmful factors

If conventional infrared shielding materials are used, then near-infrared absorption is achieved, but weather resistance is insufficient

Engineering Contradiction:
Improvenear-infrared absorptionVSAvoidweather resistance
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-coating the spherical particles with a protective layer before dispersion in the binder. This preliminary protective coating on the particles provides enhanced weather resistance from the outset, protecting the particles from environmental degradation and ensuring long-term durability of the infrared shielding function.

Inventive Principle:
Principle #10Preliminary action

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 particles provide effective near-infrared absorption with improved weather resistance, maintaining transparency and reducing visible light scattering, suitable for applications requiring clear visibility and durability.

Implementation Method 1

near-infrared absorbing material particles which contain composite tungsten oxide particles

Methodology Applied
Scientific EffectNear-infrared absorption: Absorption (EM radiation)

Implementation Method 2

coated with Si, Ti, or Zr compounds for enhanced weather resistance and reduced visible light scattering

Methodology Applied
Scientific EffectSurface deposition: Deposition (physical)

Data Source

PatentEP4082972B1Near-infrared absorbing material particles, near-infrared absorbing material particle dispersing solution, and near-infrared absorbing material particle dispersion
Publication Date: 2025.08.20 SUMITOMO METAL MINING CO LTD
  • EP4082972B1 patent drawingFigure 1
  • EP4082972B1 patent drawingFigure 2

AI summary

Near-infrared absorbing material particles contain composite tungsten oxide particles represented by a general formula MxWyOz, wherein the element M is one or more of elements selected from H, He, an alkali metal, an alkaline earth metal, a rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I, wherein the W is tungsten, wherein the O is oxygen, and wherein the x, y, and z satisfy 0.001≤x/y≤1 and 3.0<z/y.