Pressure-Sensitive Adhesive Composition for Stable Liquid Crystal Cell Gaps
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Solution Overview
Problem
The challenge in maintaining a stable cell gap and securing a strong attachment force between substrates in liquid crystal cells leads to defects such as pressing or pushing of the pressure-sensitive adhesive, affecting electro-optical properties and appearance uniformity.
Innovation Solution
A pressure-sensitive adhesive with a storage elastic modulus of 700 kPa or more and a gel fraction of 35% or more, which is optically transparent and has a thickness of 3 μm to 15 μm, is used to minimize defects and ensure excellent attachment force between substrates, thereby maintaining electro-optical properties and appearance uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a pressure-sensitive adhesive is used to maintain cell gap and secure attachment force between substrates, then adhesion force is improved, but defects such as pressing or pushing of the adhesive occur during lamination or autoclave processing
Solution Approach 1:
The patent applies parameter changes by precisely controlling the storage elastic modulus within 700-2000 kPa and gel fraction within 35-50% ranges. These parameter optimizations enable the adhesive to maintain proper cell gap and provide sufficient adhesion force while preventing pressing or pushing defects during lamination and autoclave processing, thereby resolving the contradiction between strength and manufacturing precision.
2Stability of the object's composition
If the storage elastic modulus of the pressure-sensitive adhesive is increased to maintain cell gap, then cell gap stability is improved, but the adhesive becomes more prone to pressing or pushing defects
Solution Approach 1:
The patent resolves this contradiction through parameter changes by establishing an optimal storage elastic modulus range of 700-2000 kPa. This controlled parameter range provides sufficient cell gap stability while preventing the adhesive from becoming too rigid and susceptible to pressing or pushing defects during manufacturing processes.
Solution Approach 2:
The patent employs composite materials by formulating the pressure-sensitive adhesive with specific gel fraction (35-50%) in combination with the controlled storage elastic modulus. This composite approach creates an adhesive composition that balances structural stability for cell gap maintenance with sufficient flexibility to prevent manufacturing defects.
3Strength
If the gel fraction of the pressure-sensitive adhesive is increased to improve attachment force, then adhesion strength is improved, but the adhesive viscosity increases making application difficult
Solution Approach 1:
The patent applies parameter changes by controlling the gel fraction within the 35-50% range. This optimized parameter level provides sufficient attachment force while preventing the adhesive from becoming too viscous for practical application, thereby resolving the contradiction between strength and ease of manufacture.
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 described pressure-sensitive adhesive effectively maintains a proper cell gap and adhesive force, reducing defects and enhancing the electro-optical properties and uniformity of liquid crystal cells, making them suitable for flexible applications.
Implementation Method 1
The pressure-sensitive adhesive may have a storage elastic modulus of 700 kPa or more at a temperature of 25° C. and a frequency of 6 rad/sec
Data Source
AI summary
A pressure-sensitive adhesive and a liquid crystal cell including the same are disclosed herein. In some embodiments, a pressure-sensitive adhesive having a storage elastic modulus of 700 kPa or more at a temperature of 25° C. and a frequency of 6 rad/sec, and a gel fraction of 35% or more, wherein the gel fraction is defined by Equation 1:B/A×100 [Equation 1]wherein, A is an initial mass (g) of the pressure-sensitive adhesive, B is a mass (g) of an insoluble content after the pressure-sensitive adhesive is immersed in a solvent at 60° C. for 24 hours and then dried at 150° C. for 30 minutes. The press-sensitive adhesive is advantageous for implementation into a flexible element between upper and lower substrates of a liquid crystal cell, and providing excellent electro-optical properties and appearance uniformity by minimizing defects.