Polymerizable Compound for Low Birefringence Retardation Films
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Solution Overview
Problem
Current polymerizable compounds for optical films struggle to achieve low birefringence and high reflection wavelength selectivity, which are essential for advanced optical applications such as retardation and reflection films.
Innovation Solution
A new polymerizable compound represented by Formula (I) is developed, featuring a specific structure that allows for low birefringence and high reflection wavelength selectivity, enabling the formation of films with improved optical properties by incorporating a (m+n)valent cyclic group, specific linking groups, and polymerizable groups, which are used in a polymerizable composition that can include additional liquid crystal compounds, chiral agents, and cross-linking agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a liquid crystal compound with high birefringence is used, then a retardation film with desired phase difference and thin film thickness can be obtained, but the reflection wavelength region selectivity deteriorates
Solution Approach 1:
The patent changes the molecular structure parameters of the liquid crystal compound by introducing specific groups (cyclohexyl, phenyl, pyridine) at defined positions (R1, R2, R3) in the core structure. This structural parameter change achieves low birefringence (Δn ≤ 0.15) while maintaining liquid crystalline properties, thereby improving reflection wavelength selectivity without sacrificing phase difference control capability
Solution Approach 2:
The patent creates a composite molecular structure combining a central six-membered ring core with specific substituent groups (cyclohexyl at R1, phenyl or pyridine at R2, and functional groups at R3). This composite structure integrates the benefits of different molecular moieties to achieve the desired optical properties: low birefringence from the core structure while maintaining liquid crystalline behavior through the substituent groups
2Measurement precision
If a non-liquid-crystalline (meth)acrylate compound is used, then a reflection film with high reflection wavelength region selectivity can be obtained, but the liquid crystalline properties required for optical film formation are lost
Solution Approach 1:
The patent modifies the molecular parameters by introducing polymerizable groups (acryloyl, methacryloyl, vinyl) at the R3 position while maintaining the liquid crystalline core structure. This parameter change enables the compound to exhibit both liquid crystalline properties (for film formation) and low birefringence (for high wavelength selectivity), resolving the contradiction between maintaining liquid crystalline behavior and achieving high reflection selectivity
Solution Approach 2:
The patent designs a multi-functional molecular structure where the same compound serves multiple purposes: the core structure provides liquid crystalline behavior for film formation, while the specific substituent groups (cyclohexyl, phenyl, pyridine) at R1-R3 positions provide low birefringence for high wavelength selectivity. The polymerizable groups enable crosslinking for enhanced film stability. This multi-functionality eliminates the need to choose between liquid crystalline properties and reflection selectivity
3Ease of manufacture
If existing polymerizable liquid crystal compounds are used, then film formation is achieved, but the combination of low birefringence and high reflection wavelength selectivity is not obtained
Solution Approach 1:
The patent systematically changes molecular parameters by positioning specific groups at specific locations: cyclohexyl at R1, phenyl or pyridine at R2, and polymerizable groups at R3. This precise parameter control achieves the dual performance of low birefringence (for wavelength selectivity) and maintained liquid crystalline properties (for film formation), resolving the contradiction between ease of manufacture and measurement precision
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 new polymerizable compound and composition produce films with low birefringence and high reflection wavelength selectivity, resulting in films that are colorless, transparent, and suitable for various optical applications, including retardation plates, polarizers, and reflection films with enhanced weather resistance and heat resistance.
Implementation Method 1
it is possible to obtain a reflection film with high reflection wavelength region selectivity by fixing a cholesteric liquid crystalline phase, which is formed using a polymerizable compound with low birefringence
Implementation Method 2
a reflection film with high reflection wavelength region selectivity
Implementation Method 3
The birefringence of the polymerizable compound is one of the properties which greatly influences the optical properties of the obtained optical film
Implementation Method 4
a polymerizable composition which includes the polymerizable compound described above
Data Source
AI summary
The present invention provides a new polymerizable compound which is represented by Formula (I). In the formula, R1 indicates an alkyl group or the like, A represents a (m+n)valent cyclic group, L1 indicates a single bond or the like, L2 indicates —COO— or the like, Z indicates —COO— or the like, Sp indicates an alkylene group, an alkyleneoxy group, or the like, Q indicates a polymerizable group such as a (meth)acryloyl groups, 1 indicates an integer of 0 to 2, m indicates an integer of 1 or 2, and n indicates an integer of 1 to 3. The present invention also provides a polymerizable composition which includes the polymerizable compound described above, a film which is formed from the polymerizable composition described above, and a half mirror for displaying a projection image which includes the film described above. Using the polymerization composition described above, it is possible to manufacture films such as a low birefringence retardation film and a reflection film with high reflection wavelength region selectivity.