Optical Laminate Surface Energy Control for Cissing Suppression
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Solution Overview
Problem
Conventional optical laminates used in organic EL display devices experience issues with cissing and film thickness unevenness due to direct contact between optically anisotropic layers, which affects the performance and contrast of the display.
Innovation Solution
The optical laminate is designed with specific surface energy configurations, where the surface energy of one optically anisotropic layer in contact with another is optimized to 30-40 mN/m, and the surface energy of the opposite surface is maintained at 25 mN/m or less, preventing cissing and film thickness unevenness by controlling the interface energy and additive distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If optically anisotropic layers are made to come into direct contact with each other, then device complexity is reduced, but cissing occurs and film thickness unevenness is generated
Solution Approach 1:
The patent applies parameter changes by precisely controlling the surface energy of the optically anisotropic layers. The surface energy is adjusted to a specific range (20-30 mN/m) through material selection and surface treatment, which prevents cissing and film thickness unevenness while maintaining direct contact between layers. This parameter optimization resolves the contradiction by enabling simple structure without sacrificing manufacturing precision.
2Strength
If surface energy of the interface between optically anisotropic layers is increased, then adhesion between layers is improved, but cissing may occur
Solution Approach 1:
The patent resolves this contradiction by optimizing the surface energy parameter to a specific range (20-30 mN/m). This balanced parameter value provides sufficient interlayer adhesion strength while preventing the excessive surface energy that causes cissing. The precise parameter control enables simultaneous achievement of good adhesion and absence of harmful effects.
3Object-generated harmful factors
If surface energy of the air interface of an optically anisotropic layer is decreased, then cissing is suppressed, but film thickness unevenness may be generated
Solution Approach 1:
The patent resolves this contradiction by maintaining the surface energy within the optimized range (20-30 mN/m). This parameter setting suppresses cissing by preventing excessive surface tension while avoiding the conditions that lead to film thickness unevenness. The balanced parameter value simultaneously achieves both benefits.
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
This configuration effectively suppresses cissing and film thickness unevenness, enhancing the performance and contrast of the organic EL display devices by maintaining uniformity and preventing reflection issues.
Implementation Method 1
a phase difference plate including a transparent support, and a laminated optically anisotropic layer having a first optically anisotropic layer (H) which is formed of a composition containing a discotic liquid crystal compound
Implementation Method 2
either or both of the optically anisotropic layer A and the optically anisotropic layer B are formed of a composition containing a liquid crystal compound
Implementation Method 3
surface energy A of a surface of the optically anisotropic layer A on a side in contact with the optically anisotropic layer B is 30 to 40 mN/m, surface energy B1 of a surface of the optically anisotropic layer B on a side in contact with the optically anisotropic layer A is 35 mN/m or more, and surface energy B2 of a surface of the optically anisotropic layer B opposite to the side in contact with the optically anisotropic layer A is 25 mN/m or less
Data Source
AI summary
The present invention provides an optical laminate in which cissing occurring when an optically anisotropic layer is formed and film thickness unevenness are suppressed, and a polarizing plate and an organic EL display device using the same. The optical laminate includes an optically anisotropic layer A, and an optically anisotropic layer B, where layer A and layer B come into direct contact, either or both of layer A and layer B are formed of a composition containing a liquid crystal compound, surface energy A of a surface of layer A on a side in contact with layer B is 30 to 40 mN/m, surface energy B1 of a surface of layer B on a side in contact with layer A is 35 mN/m or more, and surface energy B2 of a surface of layer B opposite to the side in contact with layer A is 25 mN/m or less.