Pressure-Sensitive Adhesive IPN Structure for LCD Light Leakage
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Solution Overview
Problem
Pressure-sensitive adhesive compositions for polarizing plates in liquid crystal display devices face challenges in maintaining durability and preventing light leakage under high-temperature and high-humidity conditions, with existing solutions either compromising on modulus of elasticity or yield due to single cross-linking structures.
Innovation Solution
A pressure-sensitive adhesive composition forming an interpenetrating polymer network (IPN) with a cross-linkable acrylic polymer, a cross-linking agent, and a multifunctional acrylate, which adjusts the X value between 60% to 80% to achieve optimal durability and light leakage suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single cross-linking structure is used in the pressure-sensitive adhesive, then the manufacturing process is simple, but the modulus of elasticity cannot be sufficiently increased to suppress light leakage while maintaining durability
Solution Approach 1:
The patent employs a dual cross-linking structure comprising both silane-based cross-linking and polyene-based cross-linking within the same pressure-sensitive adhesive composition. This composite cross-linking system creates a complex three-dimensional network that simultaneously achieves high modulus of elasticity (≥200 kgf/cm²) for light leakage suppression and maintains durability, resolving the limitation of single cross-linking structures
2Object-affected harmful factors
If the modulus of elasticity of the pressure-sensitive adhesive is increased to suppress light leakage, then optical properties improve, but durability may be degraded due to decreased strength
Solution Approach 1:
The dual cross-linking structure creates a balanced three-dimensional network where silane cross-linking provides structural rigidity for high modulus of elasticity (suppressing light leakage) while polyene cross-linking maintains flexibility and adhesive strength (preserving durability). This composite approach allows simultaneous achievement of both requirements
Solution Approach 2:
The patent precisely controls the ratio of silane cross-linking to polyene cross-linking, with the silane cross-linking accounting for 20-80% of total cross-linking. By adjusting this parameter, the modulus of elasticity and strength can be optimized to simultaneously achieve light leakage suppression and maintain durability
3Stability of the object's composition
If a pressure-sensitive adhesive with stress relaxation property is used to prevent birefringence, then optical uniformity improves, but creeping or squeezing occurs during manufacture leading to decreased yield
Solution Approach 1:
The patent controls the glass transition temperature (Tg) of the pressure-sensitive adhesive to be -50°C to 0°C, providing stress relaxation capability for optical uniformity. Simultaneously, the dual cross-linking structure creates sufficient internal strength to prevent excessive creeping or squeezing during manufacturing, thereby maintaining high yield
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 IPN structure enhances durability and workability under extreme conditions while effectively preventing light leakage in polarizing plates, maintaining suitable modulus of elasticity and peel strength.
Implementation Method 1
a cross-linking agent that is capable of forming a cross-linking structure by being reacted with the cross-linkable acrylic polymer
Implementation Method 2
a method of forming a separate cross-linking structure by adding a photoinitiator and a multifunctional acrylate to a pressure-sensitive adhesive composition
Data Source
AI summary
A pressure-sensitive adhesive composition, a pressure-sensitive adhesive polarizing plate and a liquid crystal display device are provided. The pressure-sensitive adhesive composition has excellent durability reliability under extreme conditions such as high temperature and/or humidity conditions, and shows superior workability such as cuttability or re-workability. Also, when the pressure-sensitive adhesive composition is applied to a polarizing plate or a liquid crystal display device, the composition can effectively prevent light leakage. Such a pressure-sensitive adhesive exhibits excellent characteristics, for example, even when the pressure-sensitive adhesive is applied to a 20-inch or more large display device.