Liquid Crystal Composition Homeotropic Alignment Without Films
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Solution Overview
Problem
Conventional liquid crystal display devices face challenges in achieving homeotropic alignment of liquid crystal molecules without alignment films, requiring additional steps and potentially decreasing electric resistance, while also striving for high maximum temperature, low minimum temperature, small viscosity, suitable optical anisotropy, large positive dielectric anisotropy, high stability to ultraviolet light and heat, and long service life.
Innovation Solution
A liquid crystal composition with positive dielectric anisotropy, incorporating a polar compound with a polymerizable group that allows for homeotropic alignment and includes compounds represented by specific formulas, which are mixed with other liquid crystal compounds and additives to achieve desired characteristics such as a high maximum temperature, low minimum temperature, and improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alignment films are used to achieve homeotropic alignment of liquid crystal molecules, then alignment is achieved, but device complexity increases and electric resistance decreases
Solution Approach 1:
The invention extracts and eliminates the alignment film component from the liquid crystal display device structure. Instead of using a separate alignment film layer, the patent incorporates alignment functionality directly into the liquid crystal composition through polar compounds with polymerizable groups that induce homeotropic alignment when polymerized, thereby reducing device complexity while maintaining alignment quality
Solution Approach 2:
The invention introduces polar compounds with polymerizable groups as intermediary substances within the liquid crystal composition. These compounds act as mediators that transfer alignment information to the liquid crystal molecules through their polar groups, enabling homeotropic alignment without requiring external alignment films. The polymerizable groups allow these intermediaries to form stable polymer networks that maintain alignment
2Temperature
If the maximum temperature of the nematic phase is increased to expand operating temperature range, then high-temperature performance improves, but viscosity increases and response time worsens
Solution Approach 1:
The invention employs parameter changes by carefully selecting and combining liquid crystal compounds with different molecular structures and properties. The composition includes specific ratios of compounds with varying chain lengths, ring structures, and functional groups to optimize the balance between maximum nematic phase temperature and viscosity, achieving a maximum temperature of at least 70°C while maintaining acceptable response characteristics
Solution Approach 2:
The invention uses composite materials by formulating a multi-component liquid crystal composition rather than using a single compound. The composition includes at least three types of liquid crystal compounds with different molecular characteristics, creating a composite system where the synergistic effects of the components achieve both high maximum temperature and acceptable viscosity that cannot be obtained with individual compounds alone
3Reliability
If polar compounds with polymerizable groups are added to achieve homeotropic alignment, then alignment control improves, but compatibility with liquid crystal compounds must be optimized
Solution Approach 1:
The invention applies local quality by using polar compounds with specific local molecular structures and functional groups that provide strong polar interactions for alignment control while maintaining overall compatibility with the liquid crystal composition. The polymerizable groups are strategically positioned to enable localized polymerization that induces alignment without disrupting the bulk composition stability
Solution Approach 2:
The invention optimizes compatibility by carefully controlling the concentration and molecular parameters of polar compounds with polymerizable groups in the composition. The patent specifies that these compounds should constitute 0.01-10 wt% of the total composition and have specific molecular weight ranges and structural parameters that ensure both effective alignment control and stable mixing with liquid crystal compounds without phase separation or precipitation
Data Source
AI summary
The subject is to show a liquid crystal composition in which the homeotropic alignment of liquid crystal molecules can be achieved by the action of a polymer, and a liquid crystal display device including this composition.The means concerns a nematic liquid crystal composition that has positive dielectric anisotropy and that includes a specific liquid crystal compound having a large positive dielectric anisotropy as a first component and a polar compound having a polymerizable group as a first additive, and the composition may include a specific liquid crystal compound having a high maximum temperature or a small viscosity as a second component, a specific liquid crystal compound having a positive dielectric anisotropy as a third component, a specific liquid crystal compound having negative dielectric anisotropy as a fourth component, and a polymerizable compound as a second additive, and concerns a liquid crystal display device including the composition.