IPN Pressure-Sensitive Adhesive for Polarizing Plate Dimensional Stability
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Solution Overview
Problem
Pressure-sensitive adhesives used in polarizing plates for liquid crystal displays face issues with dimensional stability under high temperature and humidity, leading to birefringence, light leakage, and reduced durability due to inadequate stress relaxation and cuttability, as well as initial adhesion strength and storage modulus limitations.
Innovation Solution
A pressure-sensitive adhesive composition with an interpenetrating polymer network (IPN) structure, formed by reacting a cross-linkable acrylic resin with a multifunctional cross-linking agent and multifunctional acrylate, and a polymerization initiator, achieving a storage modulus of 0.05 MPa to 0.3 MPa at 80°C and 0.07 MPa to 0.25 MPa at 23°C, enhancing endurance reliability and removability while minimizing light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the pressure-sensitive adhesive is designed to have high creep and be easily deformed to secure stress relaxation properties, then stress relaxation is improved, but cuttability deteriorates causing depression or sticking-out during manufacturing
Solution Approach 1:
The patent applies parameter changes by carefully controlling the storage modulus within specific ranges (0.05-0.3 MPa at 80°C and 0.07-0.25 MPa at 23°C) and designing the adhesive to exhibit viscoelastic behavior with specific loss modulus to storage modulus ratios. This allows the adhesive to have optimal balance between stress relaxation and cuttability through quantitative parameter optimization rather than qualitative changes.
Solution Approach 2:
The patent uses composite materials by formulating the pressure-sensitive adhesive as a composition containing multiple components including cross-linkable acrylic resin, multifunctional cross-linking agent, and various additives in specific proportions. This composite structure enables simultaneous achievement of stress relaxation properties and manufacturability that cannot be obtained with single-component adhesives.
2Stability of the object's composition
If the pressure-sensitive adhesive is designed to be very hard to inhibit shrinkage and expansion, then dimensional stability is improved, but initial adhesion strength is reduced
Solution Approach 1:
The patent resolves this contradiction through parameter changes by controlling the storage modulus within specific ranges and designing the adhesive to exhibit viscoelastic behavior with controlled loss modulus to storage modulus ratios. This allows the adhesive to have optimal balance between dimensional stability and initial adhesion strength.
Solution Approach 2:
The patent applies dynamics by designing the adhesive to exhibit time-dependent and temperature-dependent mechanical properties. The viscoelastic behavior allows the adhesive to be soft and compliant initially for good adhesion, then progressively stiffer for dimensional stability, capturing the dynamic nature of the material response.
3Stability of the object's composition
If the pressure-sensitive adhesive has high storage modulus to maintain rigidity, then shrinkage and expansion are inhibited, but adhesion strength and durability are reduced
Solution Approach 1:
The patent applies parameter changes by controlling the storage modulus within specific ranges (0.05-0.3 MPa at 80°C and 0.07-0.25 MPa at 23°C) and designing the adhesive to exhibit viscoelastic behavior with specific loss modulus to storage modulus ratios. This allows the adhesive to have optimal balance between shrinkage/expansion control and adhesion strength.
Solution Approach 2:
The patent applies dynamics by designing the adhesive to exhibit time-dependent and temperature-dependent mechanical properties. The viscoelastic behavior allows the adhesive to be soft and compliant initially for good adhesion, then progressively stiffer for dimensional stability, capturing the dynamic nature of the material response.
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 provides excellent physical properties such as endurance reliability, removability, and light transmission uniformity, effectively addressing the challenges of dimensional stability and adhesion strength in polarizing plates, even under high-temperature and high-humidity conditions.
Implementation Method 1
a cross-linked structure formed by reaction of a crosslinkable acrylic resin and a multifunctional crosslinking agent capable of realizing the cross-linked structure by reacting with the acrylic resin
Implementation Method 2
a crosslinked structure formed by a reaction of a multifunctional acrylate and a polymerization initiator
Data Source
AI summary
The present invention relates to a pressure-sensitive adhesive composition, a polarizing plate and a liquid crystal display. In the present invention, provided is a pressure-sensitive adhesive which can effectively prevent the light leakage resulting from dimensional changes of the polarizing plate, and the like, and exhibit excellent endurance reliability even when it is used or stored for a long time. Further, in the present invention, provided is the pressure-sensitive adhesive composition or the pressure-sensitive adhesive which can exhibit excellent physical properties, such as removability, workability, and the like.