Optical Laminate Mixed Layer Adhesiveness
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Solution Overview
Problem
Existing optical laminates with multiple optically anisotropic layers face challenges in achieving excellent adhesiveness between layers and alignment properties, particularly between A-plates and C-plates, as well as between A-plates and pressure-sensitive adhesives, which affects their performance in image display devices.
Innovation Solution
The introduction of a mixed layer between the A-plate and C-plate, comprising components from both liquid crystal compounds and a photo-alignment compound, with specific surface energy and thickness conditions, enhances adhesiveness and alignment properties by using time-of-flight secondary ion mass spectrometry to analyze and optimize the distribution of secondary ions within the laminate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple optically anisotropic layers are laminated to improve display performance, then the functional performance is improved, but the adhesiveness between layers deteriorates
Solution Approach 1:
A mixed layer comprising components from both first and second liquid crystal compounds is introduced between the first optically anisotropic layer (A-plate) and the second optically anisotropic layer (C-plate). This intermediate layer acts as a mediator that enhances adhesiveness between the two optically anisotropic layers while maintaining their individual optical functions, thereby resolving the contradiction between improved display performance and deteriorated layer adhesiveness.
Solution Approach 2:
The mixed layer is formed as a composite material containing components from both the first liquid crystal compound (in the A-plate) and the second liquid crystal compound (in the C-plate). This composite structure provides both strong adhesion to the A-plate and good adhesion to the C-plate, simultaneously achieving excellent adhesiveness between layers while maintaining the optical anisotropy and display performance of both layers.
2Manufacturing precision
If a photo-alignment compound is used to improve liquid crystal alignment, then the alignment properties are improved, but the adhesiveness between layers deteriorates
Solution Approach 1:
The patent applies local quality by having the photo-alignment compound segregated toward the air side of the A-plate, specifically in the region adjacent to the mixed layer. This localized concentration of the photo-alignment compound ensures excellent liquid crystal alignment properties at the critical interface with the C-plate, while the mixed layer's composition is designed to maintain strong adhesiveness, thus resolving the contradiction between improved alignment and deteriorated adhesiveness.
3Strength
If the A-plate surface is modified to improve adhesiveness with pressure-sensitive adhesive, then the adhesiveness is improved, but the liquid crystal alignment properties deteriorate
Solution Approach 1:
The patent applies local quality by concentrating the photo-alignment compound in the region adjacent to the mixed layer, specifically toward the air side of the A-plate. This localized placement ensures that the alignment function is concentrated where it is most needed (at the interface with the C-plate through the mixed layer), while the overall A-plate structure maintains good adhesiveness with the pressure-sensitive adhesive on its opposite side, thus resolving the contradiction between improved adhesiveness and deteriorated alignment.
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
This configuration significantly improves the adhesiveness between the A-plate and C-plate, maintains excellent liquid crystal alignment, and enhances the adhesiveness between the A-plate and pressure-sensitive adhesive, leading to improved performance in optical laminates, polarizing plates, and image display devices.
Implementation Method 1
conditions which will be described later are satisfied in a case where a component in a depth direction of the optical laminate is analyzed with time-of-flight type secondary ion mass spectrometry while irradiating ion beams from a surface of the optical laminate on a first optically anisotropic layer side toward the second optically anisotropic layer side
Implementation Method 2
a component in a depth direction of the optical laminate is analyzed with time-of-flight type secondary ion mass spectrometry
Implementation Method 3
the mixed layer further includes a photo-alignment compound
Data Source
AI summary
An optical laminate includes two optically anisotropic layers, an A-plate and a C-plate, in which the adhesiveness between the layers, the liquid crystal alignment of the C-plate, and the adhesiveness between the A-plate and a pressure-sensitive adhesive, are excellent. The optical laminate includes first and second optically anisotropic layers which are A-plate and C-plate formed of a first and second liquid crystal compound, respectively, and a mixed layer disposed between the layers, including components derived from the first and second liquid crystal compounds, and an optical alignment compound, in which a surface energy of the first optically anisotropic layer on a side opposite to the mixed layer is 25 mN/m or more, and where a component in a depth direction is analyzed with time-of-flight type secondary ion mass spectrometry while irradiating ion beams from a surface of the optical laminate on the first, toward the second, optically anisotropic layer.