Photo-alignment Copolymer Side Chain Cleaving Group
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Solution Overview
Problem
The coatability of optically anisotropic layers on photo-alignment films deteriorates, affecting the performance of image display devices, particularly in terms of upper layer coatability and liquid crystal alignment.
Innovation Solution
A photo-alignment copolymer is developed, comprising repeating units with photo-alignment, crosslinkable, and cleaving groups, where the cleaving group is on a side chain and produces a polar group upon action by light, heat, acid, or base, allowing uneven distribution and improved coatability and alignment properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photo-alignment film containing a copolymer with crosslinkable groups is used, then liquid crystal alignment is improved, but upper layer coatability deteriorates
Solution Approach 1:
The patent introduces a cleaving group that undergoes structural transformation under specific conditions (heat, light, acid, or base treatment). This parameter change allows the polymer to transition from a state that provides good alignment to a state that improves coatability, resolving the contradiction between alignment performance and manufacturing ease.
Solution Approach 2:
The photo-alignment copolymer is designed with dynamic characteristics where the cleaving group can change its structural state based on external stimuli. This dynamic property enables the material to adapt its surface characteristics for different process requirements - providing alignment during liquid crystal formation and improving coatability during subsequent upper layer formation.
2Ease of manufacture
If the cleaving group is positioned on the side chain rather than the main chain, then upper layer coatability is improved, but the complexity of polymer structure increases
Solution Approach 1:
The patent segments the functional groups into distinct positions within the polymer structure - placing the cleaving group on the side chain rather than the main chain. This segmentation allows the main chain to maintain its structural simplicity and continuity while the side chain provides the necessary functional complexity for coatability improvement.
Solution Approach 2:
The cleaving group is localized to specific positions on the side chain rather than being distributed throughout the entire polymer structure. This local quality approach concentrates the functional complexity only where needed for coatability, while the rest of the polymer structure remains simple and easy to manufacture.
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 use of this copolymer enhances upper layer coatability and liquid crystal alignment, reducing film thickness unevenness and improving the overall performance of optical laminates and image display devices.
Implementation Method 1
a cleaving group which decomposes by the action of at least one selected from the group consisting of light, heat, an acid, and a base to produce a polar group
Implementation Method 2
a crosslinkable group which causes a crosslinking reaction by the action of at least one selected from the group consisting of light, heat, an acid, and a base
Implementation Method 3
a photo-alignment film subjected to a photo-alignment treatment in place of a rubbing treatment has been known
Data Source
AI summary
An object of the invention is to provide a photo-alignment copolymer capable of improving upper layer coatability after layer formation, a binder composition, a binder layer, an optical laminate, and an image display device. A photo-alignment copolymer according to the embodiment of the invention has a repeating unit A including a photo-alignment group, a repeating unit B including a crosslinkable group which causes a crosslinking reaction by the action of at least one selected from the group consisting of light, heat, an acid, and a base, and a repeating unit C including a cleaving group which decomposes by the action of at least one selected from the group consisting of light, heat, an acid, and a base to produce a polar group, and the repeating unit C has the cleaving group on a side chain, and has a group of atoms which is provided on a side closer to a terminal than the cleaving group on the side chain to be able to unevenly distribute the photo-alignment copolymer on an air interface side.