Binder Composition for Liquid Crystal Alignment via Hydrogen Bonding
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Solution Overview
Problem
The coatability and liquid crystal aligning properties of optically anisotropic layers can deteriorate due to the type of fluorine-based surfactant used, affecting the performance of optical films in image display devices.
Innovation Solution
A binder composition containing a binder, a polymerization initiator, a surfactant, and a photo-alignment agent, where the surfactant and photo-alignment agent include functional groups capable of hydrogen bonding, with proton-donating and proton-accepting groups respectively, to enhance upper layer coatability and liquid crystal aligning properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fluorine-based surfactant is used in the liquid crystal composition, then the coatability of the optically anisotropic layer is improved, but the liquid crystal aligning properties deteriorate
Solution Approach 1:
A binder layer is introduced as an intermediary between the substrate and the optically anisotropic layer. This binder layer contains a surfactant and a photo-alignment agent that work together to provide both good coatability for the upper layer and proper liquid crystal alignment, resolving the contradiction by separating the coatability function from the alignment function into different layers.
Solution Approach 2:
The binder layer uses a composite formulation combining a binder, surfactant, and photo-alignment agent. This composite material provides dual functionality: the surfactant ensures coatability while the photo-alignment agent ensures proper liquid crystal alignment, thus resolving the contradiction between ease of manufacture and reliability.
2Quantity of substance
If a fluorine-based surfactant is used in the liquid crystal composition, then the spreading properties are improved, but the alignment uniformity deteriorates
Solution Approach 1:
The functions of spreading and alignment are segmented into different components within the binder layer. The surfactant handles the spreading function while the photo-alignment agent handles the alignment function, allowing both to operate optimally without interfering with each other, thus resolving the contradiction between quantity of substance and manufacturing precision.
3Stability of the object's composition
If the liquid crystal composition contains a polymerizable group, then the layer stability is improved, but the alignment properties deteriorate
Solution Approach 1:
The photo-alignment agent is applied in advance to the binder layer before the liquid crystal layer is formed. This preliminary action establishes the alignment pattern that will guide the liquid crystal molecules, ensuring proper alignment properties even when the liquid crystal composition contains polymerizable groups that may affect 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
The binder composition improves upper layer coatability and liquid crystal aligning properties, leading to enhanced performance in optical laminates and image display devices.
Implementation Method 1
the surfactant and the photo-alignment agent include functional groups capable of hydrogen bonding with each other, the functional group capable of hydrogen bonding included in any one of the surfactant or the photo-alignment agent is a proton-donating functional group, and the functional group included in the other of the surfactant or the photo-alignment agent is a proton-accepting functional group
Data Source
AI summary
An object of the present invention is to provide a binder composition which is excellent in upper layer coatability after being formed as a binder layer and can improve liquid crystal aligning properties, a binder layer, an optical laminate, and an image display device. A binder composition according to the embodiment of the present invention is a binder composition containing: a binder; a polymerization initiator; a surfactant; and a photo-alignment agent, in which the surfactant and the photo-alignment agent include functional groups capable of hydrogen bonding with each other, and the functional group capable of hydrogen bonding included in any one of the surfactant or the photo-alignment agent is a proton-donating functional group, and the functional group included in the other of the surfactant or the photo-alignment agent is a proton-accepting functional group.