Optical Element Alignment Layer Crosslinking for Adhesion
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Solution Overview
Problem
Existing optical elements with liquid crystal layers face issues of poor adhesive properties between the alignment layer and the refractive index anisotropic layer, leading to peeling and display unevenness, especially at high temperatures and humidity, and previous solutions either increase production costs or hinder proper alignment of liquid crystal molecules.
Innovation Solution
A transparent base material with an alignment property providing layer made of a polymer and monomer or oligomer with functional groups, which crosslinks with the polymerizable liquid crystal material in the refractive index anisotropic layer, enhancing the adhesive and endurance properties through a photo alignment method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a polymerizable liquid crystal material is used to form the refractive index anisotropic layer, then the optical property is improved, but the adhesive property between the alignment layer and the refractive index anisotropic layer deteriorates, causing peeling and display unevenness
Solution Approach 1:
The patent changes the chemical composition parameters of the alignment layer by incorporating polymerizable groups and using specific solvents that can participate in crosslinking reactions. This parameter change enables the alignment layer to chemically bond with the polymerizable liquid crystal layer, resolving the adhesive property deterioration while maintaining optical performance
Solution Approach 2:
The patent creates a composite structure where the alignment layer and refractive index anisotropic layer are chemically bonded through crosslinking. The alignment layer contains polymers with polymerizable groups (acrylate, methacrylate, vinyl groups) that form composite material bonds with the polymerizable liquid crystal material, preventing peeling and improving reliability
2Manufacturing precision
If rubbing treatment is applied to the alignment layer to achieve alignment, then the alignment property is improved, but static electricity and dust are generated, affecting quality
Solution Approach 1:
The patent replaces the mechanical rubbing treatment with a photoalignment method. By incorporating polymerizable groups in the alignment layer and irradiating with polarized light, molecular alignment is achieved through photochemical reactions rather than mechanical contact, eliminating static electricity and dust generation while maintaining alignment precision
Solution Approach 2:
The patent changes the alignment mechanism from mechanical (rubbing) to photochemical (photoalignment). The alignment layer is designed with polymerizable groups that undergo photochemical reactions when irradiated with polarized light, changing the molecular orientation through chemical parameter changes rather than mechanical force, thus avoiding harmful factors
3Reliability
If the adhesive property between layers is improved by chemical bonding, then the endurance at high temperature and humidity is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent merges the alignment layer formation and adhesive bonding functions into a single integrated process. The alignment layer is formed with polymerizable groups incorporated during the same coating and curing process that creates the alignment function, eliminating the need for separate adhesive layers or additional bonding steps, thus improving endurance without significantly increasing manufacturing complexity
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 significantly improves the adhesive property and endurance of the optical element, preventing peeling and display unevenness, while maintaining optimal alignment and optical performance.
Implementation Method 1
The photo alignment method is classified into 'photo isomerization', in which only the shape of molecules is changed to vary the alignment state thereof reversibly, and 'photo reaction', in which molecules themselves are changed.
Implementation Method 2
the monomer or oligomer in the alignment layer and the polymerizable liquid crystal material in the refractive index anisotropic layer are crosslinked with each other near an interface between the layers
Data Source
AI summary
The present invention provides an optical element capable of improving the adhesive property between a refractive index anisotropic layer and an alignment property providing layer for providing alignment property to the refractive index anisotropic layer and further improving the endurance of each of the layers.