Cholesteric Monolayer Nanoparticle Dispersion Hiding Power
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Solution Overview
Problem
Cholesteric liquid-crystal layers and pigments lack hiding power and brilliance when additional properties like conductivity or magnetism are introduced, as incorporating non-liquid-crystalline materials disrupts their orientability and color reflection properties, and existing multilayer solutions are complex and prone to delamination.
Innovation Solution
Incorporating nanoparticles with additional properties directly into the cholesteric matrix at a temperature above the clearing point of the liquid-crystal mixture, allowing for the creation of three-dimensionally crosslinked cholesteric monolayers and pigments with enhanced hiding power, conductivity, and color-changing effects without the need for additional layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If absorbent or opaque materials are added to cholesteric LC mixtures to increase hiding power, then hiding power is improved, but orientability is impaired causing loss of reflection properties and colour
Solution Approach 1:
The patent applies parameter changes by using nanoparticles with specific size parameters (1-100 nm, preferably 5-50 nm) and controlling their concentration (0.1-10 wt%). This size parameter allows the particles to be small enough not to disrupt the cholesteric helical structure and orientability, while still providing sufficient hiding power through their optical properties
Solution Approach 2:
The patent creates a composite material system by combining cholesteric liquid crystal molecules with nanoparticles of various materials (metal oxides, magnetic particles, fluorescent particles, etc.). This composite approach allows the nanoparticles to provide additional properties (hiding power, magnetism, fluorescence) without disrupting the LC matrix when properly sized and dispersed
2Adaptability or versatility
If extraneous pigments are incorporated into the cholesteric matrix to achieve additional properties, then conductivity or magnetism is improved, but reflection properties and colour are lost or greatly reduced
Solution Approach 1:
The critical parameter change is the nanoparticle size (1-100 nm), which is sufficiently small to not disrupt the cholesteric helical pitch and optical reflection properties. The small size allows the nanoparticles to be dispersed within the LC matrix without significantly affecting the collective molecular orientation needed for selective reflection
Solution Approach 2:
The nanoparticles provide local additional properties (magnetism, conductivity, fluorescence) at specific locations within the LC matrix, while the overall cholesteric structure maintains its global optical reflection properties. Each nanoparticle contributes its specific property locally without disrupting the global LC order
3Reliability
If multilayer products are produced to achieve better hiding power, then hiding power is improved, but device complexity increases and delamination risk occurs
Solution Approach 1:
The patent merges multiple functions into a single homogeneous layer by incorporating nanoparticles directly into the cholesteric LC matrix. This eliminates the need for separate absorptive layers, reducing structural complexity from multiple layers to a single integrated layer while maintaining both optical reflection and hiding power properties
Solution Approach 2:
The nanoparticle-containing cholesteric LC layer serves multiple functions simultaneously: it provides selective colour reflection (cholesteric property), hiding power (nanoparticle absorption/scattering), and can provide additional properties like magnetism or fluorescence. This multi-functionality in a single layer eliminates the need for separate functional layers
4Reliability
If nanoparticles are incorporated into the cholesteric matrix, then hiding power and additional properties are improved, but dispersion difficulty increases
Solution Approach 1:
The nanoparticle size parameter (1-100 nm) is optimized to balance dispersion ease and hiding power. The small size reduces sedimentation and aggregation tendencies, improving dispersion stability, while still providing sufficient optical interaction for hiding power. The patent also specifies concentration parameters (0.1-10 wt%) to optimize dispersion
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 approach results in cholesteric monolayers and pigments with increased hiding power, brilliance, and color-flop/tilt effects, maintaining the desired properties while avoiding the disadvantages of prior methods, such as delamination and complexity, and enabling thinner layer thicknesses suitable for various applications.
Implementation Method 1
a good fine dispersion of extraneous pigments in the cholesteric matrix is needed
Implementation Method 2
a selective colour reflection as a function of the viewing angle (colour-flop/tilt effect), also known as optical variability
Implementation Method 3
Materials having a liquid-crystal (LC) structure with a chiral phase (LC materials), also known as cholesteric LCs
Implementation Method 4
Absorption does not occur in LC layers. Therefore, cholesteric layers or pigments produced therefrom by comminution do not possess any hiding power
Implementation Method 5
Pigments with oriented three-dimensionally crosslinked substances with liquid-crystalline structure and chiral phase (LC pigments)
Data Source
AI summary
The invention provides novel cholesteric monolayers and pigments obtained therefrom with high brilliance and viewing angle-dependent color change (color-flop/tilt effect) with additional particular properties such as magnetizability, conductivity, fluorescence, phosphorescence and increased hiding power, a process for their production and their use.