Alignment Film Silsesquioxane Polysiloxane Image Staining
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Solution Overview
Problem
Conventional polysiloxane and polyvinyl alignment films have low alignment controllability due to wide molecular weight distribution and high flexibility, leading to solubility in liquid crystal layers and issues like image sticking and stains in liquid crystal display devices.
Innovation Solution
Introduction of a silsesquioxane (SSQ) group into polysiloxane or polyvinyl polymers by chemical bonding to reduce solubility and improve alignment stability, using the SSQ group in side chains to enhance the rigidity and reduce radical and ion generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polysiloxane or polyvinyl is used as alignment film material, then alignment uniformity is improved, but solubility in liquid crystal layer increases causing image sticking and stains
Solution Approach 1:
The patent uses a composite polymer structure combining polysiloxane backbone with grafted polyimide side chains. This composite structure integrates the high alignment uniformity of polysiloxane with the low solubility and high stability of polyimide, resolving the contradiction between alignment quality and display reliability
Solution Approach 2:
The invention applies local quality by having different parts of the polymer molecule serve different functions: the polysiloxane backbone provides alignment uniformity while the polyimide side chains provide solubility resistance. This local differentiation allows each part to optimize its specific function without compromising the other
2Reliability
If polyimide or polyamic acid is used as alignment film material, then solubility in liquid crystal layer is reduced, but alignment controllability deteriorates due to wide molecular weight distribution
Solution Approach 1:
The patent creates a composite polymer where polyimide side chains are grafted onto polysiloxane backbone. This composite structure provides the dissolution resistance of polyimide while the polysiloxane backbone ensures narrow molecular weight distribution and high alignment controllability
Solution Approach 2:
The invention uses local quality by concentrating the dissolution resistance function in the polyimide side chains while the polysiloxane backbone maintains molecular uniformity. This functional separation allows optimization of both properties without compromise
3Manufacturing precision
If highly flexible polymer chains are used to achieve high alignment uniformity, then alignment uniformity is improved, but solubility in liquid crystal increases
Solution Approach 1:
The patent combines highly flexible polysiloxane chains for alignment uniformity with rigid polyimide side chains for solubility resistance. The composite structure allows the flexible backbone to provide alignment quality while the rigid side chains prevent dissolution
Solution Approach 2:
The invention applies local quality by having the polysiloxane backbone provide flexibility for alignment uniformity while the polyimide side chains provide rigidity for solubility resistance. Each part optimizes its local function without compromising the other
Data Source
AI summary
The present invention aims to provide a liquid crystal display device in which image sticking and stains are sufficiently reduced. The present invention relates to an alignment film including: a polymer, wherein the polymer is a polysiloxane or a polyvinyl and contains a silsesquioxane group. The present invention also relates to a polymer for use in the alignment film, the polymer containing a silsesquioxane group. The present invention also relates to a liquid crystal display device including: the alignment film; a pair of substrates; and a liquid crystal layer disposed between the substrates, wherein the alignment film is disposed between at least one of the substrates and the liquid crystal layer.