Polymerizable Liquid Crystal Compound for Low Birefringence Films
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Solution Overview
Problem
Current polymerizable liquid crystal compounds used in optical films often exhibit high birefringence, which limits their ability to produce films with low birefringence or high selectivity in reflection wavelength ranges, such as retardation and reflection films.
Innovation Solution
A novel polymerizable liquid crystal compound represented by Formula (I) is developed, incorporating a nitrogen-containing saturated cyclic group and a phenylene group, which exhibits lower birefringence and improved liquid crystallinity, allowing for the creation of films with specific optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional polymerizable liquid crystal compounds are used, then liquid crystallinity is achieved, but birefringence is high which limits optical film performance
Solution Approach 1:
The patent changes the chemical structure parameters of the liquid crystal compound by introducing nitrogen-containing saturated cyclic groups (piperidine or piperazine rings) into the mesogen structure. This structural parameter change reduces the birefringence from conventional high levels to below 0.13 while maintaining liquid crystallinity, enabling production of optical films with improved optical properties
Solution Approach 2:
The patent creates a composite molecular structure combining aromatic rings (phenylene groups) with nitrogen-containing saturated cyclic groups in the mesogen. This composite structure leverages the beneficial properties of both components: the aromatic rings provide liquid crystallinity while the nitrogen-containing saturated rings reduce birefringence, achieving a balance between the two requirements
2Manufacturing precision
If low birefringence is achieved, then optical selectivity in reflection wavelength range improves, but liquid crystallinity may be insufficient
Solution Approach 1:
The patent optimizes the mesogen structure by incorporating specific nitrogen-containing saturated cyclic groups (piperidine or piperazine) with defined molecular parameters. These structural changes reduce birefringence to below 0.13 while the mesogen maintains sufficient liquid crystallinity, as evidenced by the compound's ability to form stable liquid crystalline phases suitable for optical film production
Solution Approach 2:
The patent introduces nitrogen-containing saturated cyclic groups at specific positions within the mesogen structure (as shown in Formula I). This localized structural modification targets the reduction of birefringence in specific molecular regions while preserving the overall liquid crystalline ordering, achieving low birefringence without sacrificing liquid crystallinity
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 novel compound enables the production of films with low birefringence and high selectivity in reflection wavelength ranges, enhancing their optical properties and durability under various environmental conditions.
Implementation Method 1
A birefringence of the polymerizable liquid crystal compound is one of the properties greatly relating to the optical properties of the obtained optical film
Data Source
AI summary
A polymerizable liquid crystal compound represented by Formula (I):Q1—Sp1—[A—L]—A—Sp2—Q2 (I)A represents a divalent nitrogen-containing saturated cyclic group (that may have a substituent) formed by removing two hydrogen atoms from piperidine or piperazine, a phenylene group that may have a substituent, or a trans-1,4-cyclohexylene group that may have a substituent; L represents a linking group such as —C(═O)O— or —OC(═O)—; m represents 3 to 12; Sp1 and Sp2 represent an alkylene group having 1 to 20 carbon atoms; any one of Q1 and Q2 represents a polymerizable group; and Formula (I) has a nitrogen-containing saturated cyclic group and a phenylene group that are directly bonded to each other via —C(═O)O—. By using a polymerizable composition including the polymerizable liquid crystal compound, a film such as a retardation film can have low birefringence or a reflection film can have high selectivity in a reflection wavelength range.