Pressure-Sensitive Adhesive IPN for LCD Light Leakage
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Solution Overview
Problem
Existing pressure-sensitive adhesive compositions for liquid crystal displays suffer from light leakage and reduced endurance reliability under high temperature and humidity conditions, particularly in large-sized devices, due to inadequate stress relief and re-movability.
Innovation Solution
A pressure-sensitive adhesive composition featuring interpenetrating polymer networks (IPN) with an acrylic copolymer containing a hydroxy group and an alkylene oxide unit, combined with a multi-functional isocyanate hardener, which forms a cured state with improved bulk modulus and re-movability, reducing light leakage and maintaining physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the pressure-sensitive adhesive is designed to be very hard by increasing bulk modulus, then light leakage is suppressed, but adhesive property is lowered and endurance reliability deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the gel content within 60-90% and adjusting the molecular weight of the polymer (10,000-1,000,000) to achieve the optimal balance between bulk modulus and adhesive properties. This allows the adhesive to be sufficiently hard to suppress light leakage while maintaining adequate adhesion and endurance reliability.
Solution Approach 2:
The patent uses composite materials by combining a polymer base material with specific additives including crosslinking agents and fillers. This composite structure enables the adhesive to achieve both the required hardness for light leakage suppression and the necessary adhesive properties for reliable bonding under high temperature and humidity conditions.
2Stability of the object's composition
If the pressure-sensitive adhesive has high creep against external stress, then stress relief property is improved, but tailoring property becomes poor causing crooking or pressing phenomenon
Solution Approach 1:
The patent applies parameter changes by controlling the gel content within 60-90% and adjusting the polymer molecular weight (10,000-1,000,000) to achieve the optimal balance between stress relief property and tailoring property. This parameter optimization allows the adhesive to provide sufficient stress relief while maintaining good tailoring property for flat bonding without crooking or pressing.
3Object-affected harmful factors
If multi-functional acrylate and photoinitiator are added to improve bulk modulus, then light leakage-resistance property is improved, but haze is generated and adhesive property is excessively lowered
Solution Approach 1:
The patent applies parameter changes by carefully controlling the gel content within 60-90% and optimizing the polymer molecular weight (10,000-1,000,000) to achieve sufficient light leakage resistance without excessive haze generation. This parameter optimization allows the adhesive to maintain good optical properties while providing adequate bulk modulus.
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 solution effectively suppresses light leakage and enhances endurance reliability under high temperature and humidity conditions, even in large-sized displays, while maintaining excellent physical properties such as re-movability and workability.
Implementation Method 1
a pressure-sensitive adhesive composition including interpenetrating polymer networks in a cured state, wherein the composition comprises (A) an acrylic copolymer containing a hydroxy group and an alkylene oxide unit, and (B) a multi-functional isocyanate hardener
Data Source
AI summary
The present invention relates to pressure-sensitive adhesive compositions which contain (A) hydroxyl group and alkylene oxide group containing acrylic copolymer and (B) a multifunctional isocyanate-based hardener, and form interpenetrating network structures when hardened, and polarizers and liquid crystal displays comprising the same. The pressure-sensitive adhesive compositions of the present invention exhibit superior durability, reliability, and workability and effectively prevent light leakage under high temperature and/or high humidity conditions. Particularly, the present invention provides pressure-sensitive adhesive compositions capable of significantly suppressing light leakage even in large size display devices, and polarizers and liquid crystal displays comprising the same.