Regioselective Cellulose Ester Films for LCD Light Leakage
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Solution Overview
Problem
Current cellulose ester compositions used in liquid crystal display (LCD) films face challenges in reducing light leakage and improving optical performance, particularly at increased viewing angles, due to limitations in controllable optical retardation and manufacturing processes that involve environmentally unfriendly solvents.
Innovation Solution
Development of regioselectively substituted cellulose esters with specific chromophore-acyl and pivaloyl substituents, which offer a range of degree substitutions and regioselectivity, allowing for the creation of films with tailored optical properties suitable for LCD applications, including reduced light leakage and improved birefringence characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional cellulose esters are used in LCD films, then the films can be manufactured using solvent casting, but light leakage occurs at oblique viewing angles and optical performance is limited
Solution Approach 1:
The patent applies local quality by introducing specific chromophore-acyl substituents (such as benzoyl, naphthoyl, cinnamoyl groups) at particular positions on the cellulose ester molecule. These chromophoric groups are strategically placed to modify the optical properties of the material, creating regions with enhanced light transmission and reduced leakage characteristics while maintaining the overall structural integrity of the cellulose ester film.
Solution Approach 2:
The patent employs parameter changes by modifying the degree of substitution (DS) of chromophore-acyl groups and pivaloyl groups on the cellulose ester backbone. By controlling the DS values and the ratio of different substituents, the optical parameters of the film (birefringence, retardation, light transmission) are tuned to achieve superior performance at oblique viewing angles without increasing light leakage.
2Reliability
If cellulose esters are used for LCD films, then protective and compensation functions are achieved, but the manufacturing process involves environmentally unfriendly solvents
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the cellulose ester, specifically incorporating pivaloyl groups alongside chromophore-acyl groups. This compositional modification alters the solubility and processing characteristics of the material, enabling the film to be manufactured through environmentally friendly solvent casting or melt extrusion processes while maintaining its protective and compensation functions in LCD applications.
3Ease of manufacture
If standard cellulose ester compositions are used, then manufacturing is straightforward, but optical performance and manufacturing flexibility are limited
Solution Approach 1:
The patent applies universality by designing a multi-functional cellulose ester composition that can be processed through multiple manufacturing routes (solvent casting and melt extrusion). The specific combination of chromophore-acyl and pivaloyl substituents provides both the necessary optical performance for LCD compensation films and the processing versatility to accommodate different manufacturing methods, making the material universally applicable across various production scenarios.
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 regioselectively substituted cellulose ester films demonstrate enhanced light transmission and reduced leakage at oblique viewing angles, improving the overall optical performance and manufacturing flexibility by enabling both solvent and melt casting processes.
Implementation Method 1
improved birefringence characteristics
Data Source
AI summary
Regioselectively substituted cellulose esters having a plurality of pivaloyl substituents and a plurality of aryl-acyl substituents are disclosed along with methods for making the same. Such cellulose esters may be suitable for use in films, such as +A optical films, and/or +C optical films. Optical films prepared employing such cellulose esters have a variety of commercial applications, such as, for example, as compensation films in liquid crystal displays and/or waveplates in creating circular polarized light used in 3-D technology.