Polarizing Element with Nematic Dye and Vapor Alignment
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Solution Overview
Problem
Existing polarizing elements, particularly in liquid crystal displays, face challenges with heat resistance, light fastness, and achieving high dichroism due to the limitations of iodine-based dichroic substances and traditional methods of dye alignment, such as stretching or wet film-forming processes.
Innovation Solution
A polarizing element comprising a transparent support with a light absorption anisotropic layer formed from a dichroic dye composition represented by formula (I), which has nematic mesomorphism and is aligned using a vaporization process, and a transparent resin cured layer, without liquid crystalline achromatic compounds, enhancing heat resistance and dichroic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If iodine is used as a dichroic substance in polarizing plates, then the polarizing function is achieved, but heat resistance and light fastness are insufficient due to high sublimability
Solution Approach 1:
The patent changes the chemical composition parameter by replacing iodine with organic dichroic dyes (specifically azo dyes, triphenylmethane dyes, or xanthene dyes), which have superior heat resistance and light fastness properties compared to iodine, thereby eliminating the sublimation issue while maintaining the polarizing function
Solution Approach 2:
The patent uses organic dichroic dyes that can be easily applied and fixed on the polymer substrate, replacing the need for iodine which requires complex handling due to its sublimation properties, simplifying the manufacturing process
2Reliability
If organic dichroic dyes are used to replace iodine, then heat resistance improves, but dichroic property becomes distinctly inferior
Solution Approach 1:
The patent optimizes the molecular structure parameters of the organic dichroic dyes by selecting specific types (azo dyes with -N=N- linkage, triphenylmethane dyes, or xanthene dyes) and controlling their orientation on the stretched polymer substrate, achieving both high heat resistance and superior dichroic ratio
Solution Approach 2:
The patent creates a composite structure by combining organic dichroic dyes with a polymer substrate that has been stretched to provide molecular orientation, resulting in a material that exhibits both the thermal stability of the polymer and the high dichroic ratio of the oriented dye molecules
3Manufacturing precision
If a dichroic dye is dissolved or adsorbed in a polymer material and the film is stretched, then polarizing element is formed, but a long time period and efforts are required for the stretching step
Solution Approach 1:
The patent performs preliminary stretching of the polymer substrate before dyeing, or uses pre-oriented polymer films, so that the dichroic dye molecules align with the pre-established polymer orientation during a simpler, shorter dyeing or adsorption process, significantly reducing the overall alignment time
Solution Approach 2:
The patent replaces the complex mechanical stretching process with a simpler chemical or physical adsorption process by using plasma treatment or corona discharge to create surface sites on the polymer that selectively adsorb and orient the dichroic dye molecules, eliminating the need for lengthy mechanical stretching
4Manufacturing precision
If anisotropic dye film is prepared by wet system film-forming method, then alignment is achieved, but suitable dyes are limited and high dichroism is difficult to achieve
Solution Approach 1:
The patent uses a vapor-phase deposition process where dichroic dye vapors are deposited onto a stretched polymer substrate, allowing any dichroic dye to be used regardless of solubility in water-based systems, expanding dye selection while achieving high alignment through vapor condensation on the oriented polymer surface
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 solution provides a polarizing element with improved heat resistance, high dichroic ratio, and efficient alignment, enabling better display performance in liquid crystal displays by utilizing azo dyes with nematic mesomorphism and a specific alignment method.
Implementation Method 1
utilizing e.g. intermolecular interaction of organic dye molecules, to form a polarizing film (anisotropic dye film)
Implementation Method 2
the dichroic dye composition containing at least one dichroic dye, which is represented by formula (I) and which has nematic mesomorphism
Implementation Method 3
a light absorption anisotropic layer formed of a dichroic dye composition... containing at least one dichroic dye
Implementation Method 4
a transparent resin cured layer
Data Source
AI summary
A polarizing element, containing: a transparent support; a light absorption anisotropic layer formed of a dichroic dye composition; and a transparent resin cured layer, with the layers being laminated in this order on the support, and with the composition containing at least one dichroic dye of formula (I) which has nematic mesomorphism but containing no liquid crystalline achromatic compound:wherein R1 to R4 are a hydrogen atom or a substituent; R5 and R6 are a hydrogen atom or an alkyl group; L1 represents —N═N—, —CH═N—, —N═CH—, —C(═O)O—, —OC(═O)— or —CH═CH—; A1 represents a phenyl, naphthyl or aromatic heterocyclic group; B1 represents a divalent aromatic hydrocarbon or divalent aromatic heterocyclic group; and n is an integer from 1 to 5.