Laminate with Oxygen Barrier Layers for Light Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical elements with liquid crystalline compositions containing tolan compounds face challenges in maintaining high diffraction efficiency due to photodegradation, leading to reduced light resistance.
Innovation Solution
A laminate structure comprising an optically anisotropic layer with a liquid crystal alignment pattern and paired oxygen barrier layers, where the oxygen permeability coefficient is low, effectively suppresses photodegradation by reducing singlet oxygen generation, thereby enhancing light resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid crystalline composition containing a tolan compound is used to achieve high diffraction efficiency, then the optical element exhibits high diffraction efficiency, but the tolan compound undergoes photodegradation leading to reduced light resistance
Solution Approach 1:
A polymer layer is introduced as an intermediary between the light source and the tolan compound-containing optically anisotropic layer. This polymer layer absorbs singlet oxygen generated by light irradiation, preventing it from reaching and degrading the tolan compound. The polymer acts as a sacrificial mediator that protects the sensitive tolan compound while allowing the optical element to maintain high diffraction efficiency.
Solution Approach 2:
The harmful singlet oxygen generated by light irradiation is converted into a beneficial protective mechanism. Instead of allowing singlet oxygen to degrade the tolan compound, the patent uses a polymer layer to absorb this harmful species, transforming the harmful photodegradation process into a protective shielding effect that extends the lifespan of the optical element.
2Stability of the object's composition
If the optically anisotropic layer is made from a cured liquid crystalline composition to maintain alignment pattern, then the liquid crystal alignment pattern is maintained, but photodegradation of the tolan compound occurs reducing long-term stability
Solution Approach 1:
The polymer layer is prepared in advance and positioned between the light source and the optically anisotropic layer before any photodegradation can occur. This preliminary protective barrier is already in place to absorb singlet oxygen as it is generated, preventing subsequent degradation of the tolan compound and maintaining both the alignment pattern and photostability over time.
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 laminate maintains high diffraction efficiency and improves light resistance by preventing photodegradation of the tolan compound, ensuring long-term performance.
Implementation Method 1
an oxygen permeability coefficient of the oxygen barrier layer at 25° C. and 50% RH is 1.0×10−11 cm3·cm/(cm2·s·mmHg) or less
Implementation Method 2
the optically anisotropic layer has a liquid crystal alignment pattern in which an orientation of an optical axis derived from the liquid crystal compound is changed while continuously rotating
Implementation Method 3
an optically anisotropic layer consisting of a cured layer of a composition containing a liquid crystal compound
Implementation Method 4
the above-described optical characteristics are difficult to be maintained because of photodegradation of the tolan compound
Data Source
AI summary
A first object of the present invention is to provide a laminate having excellent light resistance. In addition, a second object of the present invention is to provide an optical element including the laminate and a light guide element.A laminate of the present invention includes an optically anisotropic layer consisting of a cured layer of a composition containing a liquid crystal compound and a pair of oxygen barrier layers which are disposed on both sides of the optically anisotropic layer, in which the optically anisotropic layer has a liquid crystal alignment pattern in which an orientation of an optical axis derived from the liquid crystal compound is changed while continuously rotating along at least one in-plane direction, the composition contains a compound having a partial structure represented by Formula (I), the composition contains, as the liquid crystal compound, the compound having the partial structure represented by Formula (I), or the composition contains, as a compound which is not the liquid crystal compound, the compound having the partial structure represented by Formula (I), and an oxygen permeability coefficient of the oxygen barrier layer at 25° C. and 50% RH is 1.0×10−11 cm3·cm/(cm2·s·mmHg) or less.In Formula (I), A1 and A2 each independently represent an aromatic hydrocarbon ring group or an aromatic heterocyclic group, which may have a substituent. * represents a bonding position.