Optical Functional Layer Composition for LCD Surface Defect Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing compositions for forming optical functional layers in liquid crystal display devices face challenges with cissing defects and surface unevenness due to hydrophobicity, making it difficult to achieve both good surface condition and alignment.
Innovation Solution
A composition incorporating a copolymer with specific fluoroaliphatic group-containing monomers and vinyl ester structures is used, which improves wettability and reduces cissing by forming a high surface energy film, allowing for better lamination and alignment of liquid crystal compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a leveling agent such as a fluorine-containing polymer is added into a hard coat layer to enhance the evenness of the coating film, then the surface evenness is improved, but the surface becomes hydrophobic and recoatability deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the copolymer, specifically incorporating monomers with carboxyl groups and hydroxyl groups in controlled ratios. This parameter change enables the surface to maintain hydrophilicity (good recoatability) while achieving sufficient leveling effect through the specific molecular structure and intermolecular interactions of the copolymer.
Solution Approach 2:
The invention uses a composite copolymer structure combining different functional monomers (carboxyl-containing and hydroxyl-containing) to create a material that exhibits both leveling properties and hydrophilic surface characteristics. The synergistic effect of the composite structure resolves the contradiction between surface evenness and recoatability.
2Manufacturing precision
If the surface of the hard coat layer is made hydrophobic to improve evenness, then coating smoothness is enhanced, but lamination with subsequent layers becomes difficult
Solution Approach 1:
The invention modifies the surface energy parameters by incorporating polar functional groups (carboxyl and hydroxyl) in specific proportions. This parameter adjustment maintains surface smoothness through molecular packing and intermolecular forces while ensuring hydrophilic character for reliable lamination with subsequent optical layers.
Solution Approach 2:
The copolymer acts as an intermediary substance between the hard coat layer and subsequent optical layers. The carboxyl and hydroxyl groups on the copolymer surface provide anchoring points for adhesion to subsequent layers, while the copolymer's bulk structure provides the leveling effect, thus mediating between smoothness and lamination requirements.
3Adaptability or versatility
If fluorine-based surfactants are added to achieve even coatability and recoatability, then surface wettability is improved, but cissing defects still occur during optical functional layer formation
Solution Approach 1:
The invention employs a composite copolymer system combining carboxyl-containing and hydroxyl-containing monomers rather than using simple fluorine-based surfactants. This composite structure provides both wettability (through polar groups) and defect prevention (through controlled molecular interactions and surface energy distribution), resolving the cissing issue that plagues conventional surfactant approaches.
Solution Approach 2:
The copolymer structure creates local regions with different functional characteristics - carboxyl groups provide strong polarity and wettability at the surface, while the overall copolymer matrix provides structural integrity and controls solvent evaporation. This local differentiation of functions prevents cissing while maintaining good wettability.
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 composition effectively prevents cissing and enhances the surface condition and alignment of optical functional layers, improving the overall quality of the liquid crystal display device.
Implementation Method 1
improves wettability and reduces cissing by forming a high surface energy film
Implementation Method 2
improves wettability and reduces cissing
Implementation Method 3
the liquid crystal compound is aligned in the coating films in a desired alignment state
Data Source
AI summary
A composition for preparing an optical functional layer capable of forming an optical film having an excellent surface condition and excellent lamination properties with another layer, includes a liquid crystal compound and a copolymer, and the copolymer includes a constitutional unit corresponding to a fluoroaliphatic group-containing monomer represented by Formula I, and a constitutional unit corresponding to a monomer represented by Formula II. In Formulae I and II, R1, R10, and R3 each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, R2 represents an alkyl group having 1 to 20 carbon atoms in which at least one carbon atom has a fluorine atom as a substituent, and L represents a divalent linking group constituted by at least one selected from the group consisting of —O—, —(C═O)O—, —O(C═O)—, a divalent chain group, and a divalent aliphatic cyclic group.