Anthraquinone Liquid Crystal Composition for High-Contrast Dimming

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Solution Overview

Problem

Existing dichroic dyes used in liquid crystal light control films lack sufficient contrast and light resistance, particularly when exposed to high temperatures over long periods.

Innovation Solution

A novel anthraquinone compound with specific structural characteristics is incorporated into a liquid crystal composition, which is then used to create a light control element, enhancing contrast and light resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional dichroic dyes are used in liquid crystal light control films, then the basic light control function is achieved, but the contrast and light resistance are insufficient

Engineering Contradiction:

Improvelight resistanceVSAvoidcontrast

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The patent applies parameter changes by modifying the molecular structure of anthraquinone dyes, specifically introducing branched alkyl groups with 3-16 carbon atoms at the 1-position and hydrogen or alkyl/alkoxy groups with 1-8 carbon atoms at the 2-position. These structural parameter changes result in dyes with improved contrast (dichroic ratio ≥1.3) and enhanced light resistance for outdoor automotive applications

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite material systems by combining the novel anthraquinone dichroic dyes with liquid crystal materials to form liquid crystal compositions. This composite approach integrates the optical properties of the dye with the liquid crystal's light control capabilities, achieving both high contrast and superior light resistance in the final light control film

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If a liquid crystal light control film is used to block field of view, then transmission control is achieved, but light scattering increases causing glare

Engineering Contradiction:

Improvetransmission controlVSAvoidglare

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent utilizes color changes through the dichroic properties of the anthraquinone dye, which exhibits different light absorption characteristics in different orientations. The dye absorbs light in the visible range with high efficiency, providing dark coloring at shielding state while maintaining good visibility at transparent state, thereby reducing glare caused by light scattering

Inventive Principle:

Principle #32Color changes

3Adaptability or versatility

If dichroic dyes are used for light control applications, then basic functionality is achieved, but contrast and light resistance characteristics remain insufficient

Engineering Contradiction:

Improvelight control functionalityVSAvoidcontrast and light resistance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent systematically varies molecular parameters of the anthraquinone core structure, including the type and position of substituents (branched alkyl groups at C-1, hydrogen or alkyl/alkoxy groups at C-2), to optimize both contrast and light resistance while maintaining light control functionality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by introducing specific functional groups at particular positions on the anthraquinone molecule. The branched alkyl group at the 1-position and the hydrogen or alkyl/alkoxy group at the 2-position create localized structural features that enhance overall molecular performance for contrast and light resistance without compromising the dye's fundamental light control function

Inventive Principle:

Principle #3Local quality

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 anthraquinone compound improves the contrast and light resistance of the light control element, providing optimal performance under varying light conditions and extended outdoor exposure.

Implementation Method 1

a dichroic dye which is such a novel anthraquinone compound

Methodology Applied

Scientific EffectDichroism: Pleochroism

Implementation Method 2

absorb light in a visible range with high efficiency

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 3

a liquid crystal light control film can block a field of view by controlling transmission or scattering of light depending on whether or not a voltage is applied

Methodology Applied

Scientific EffectElectro-optic effect: Electro-Optic Effects

Data Source

PatentEP4306616B1Anthraquinone compound, liquid crystal composition containing said compound, and dimming element

Publication Date: 2025.11.19 NIPPON KAYAKU CO LTD

AI summary

The purpose of the present invention is to provide a novel anthraquinone compound, and to provide: a dichroic dye constituted of the novel anthraquinone compound; a liquid crystal composition which contains the dichroic dye; and preferably a dimming element having excellent contrast and light resistance and containing said composition. The present invention discloses an anthraquinone compound represented by formula A below (wherein R1 represents a C3-16 branched alkyl group, and R2 represents a hydrogen atom, a C1-8 straight-chain or branched alkyl group, or a C1-8 straight-chain or branched alkoxy group). In addition, the present invention discloses a liquid crystal composition including the anthraquinone compound and a liquid crystal material, and a dimming element containing said composition.