Crosslinkable Adhesive Composition for Electronic Displays
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Solution Overview
Problem
Existing adhesive compositions for electronic displays face challenges in maintaining optical, mechanical, and electrical stability due to phase separation caused by temperature and humidity fluctuations, and high viscosity issues during hot melt processing, which affect their performance as pressure-sensitive or heat bondable adhesives.
Innovation Solution
A crosslinkable composition comprising a blend of two (meth)acrylate polymers with specific molecular weight ranges and monomeric units, including hydroxy-containing monomers, which are resistant to crosslinking during extrusion and can be crosslinked using ultraviolet or ionizing radiation, forming a pressure-sensitive or heat bondable adhesive with improved hydrophilicity and dielectric properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If adhesive compositions use hydrophilic components to improve optical stability and reduce phase separation, then clarity and optical performance improve, but viscosity increases during processing
Solution Approach 1:
The patent changes the molecular weight parameters of the polymer components. Specifically, it uses a first polymer with Mw of 100,000-1,500,000 Daltons and a second polymer with Mw of 5,000-100,000 Daltons. This parameter optimization allows the composition to maintain optical stability while keeping processing viscosity within acceptable ranges for extrusion.
Solution Approach 2:
The patent creates a composite adhesive system by blending two distinct (meth)acrylate polymers with different molecular weight characteristics and functional groups. This composite approach combines the optical stability benefits of hydrophilic components with the processing advantages of optimized molecular weight distribution, resolving the viscosity-stability contradiction.
2Strength
If adhesive compositions are crosslinked to improve mechanical stability and performance, then mechanical properties improve, but crosslinking occurs during extrusion processing causing gelation
Solution Approach 1:
The patent incorporates crosslinkable functional groups (pendant (meth)acryloyl groups and pendant aromatic ketone groups) into the polymer structures during manufacturing, but these groups remain dormant during extrusion processing. The crosslinking action is triggered only after application to the substrate via UV or ionizing radiation, preventing premature gelation during processing while ensuring mechanical stability in the final product.
Solution Approach 2:
The patent carefully controls the concentration and type of crosslinkable functional groups in the polymers. By optimizing these parameters, the composition maintains sufficient stability during extrusion processing while retaining the capability to crosslink effectively after application, thus resolving the contradiction between mechanical stability and processing stability.
3Strength
If adhesive compositions use high molecular weight polymers to improve mechanical strength, then strength improves, but viscosity increases making extrusion difficult
Solution Approach 1:
The patent segments the adhesive system into two polymer components with distinctly different molecular weight ranges. The first polymer (Mw: 100,000-1,500,000 Daltons) provides mechanical strength, while the second polymer (Mw: 5,000-100,000 Daltons) acts as a processing aid that reduces viscosity. This segmentation allows each component to fulfill its specific function without compromising the other.
Solution Approach 2:
The patent creates a composite system where two polymers with complementary molecular weight characteristics work together. The high molecular weight polymer contributes strength while the low molecular weight polymer maintains processability, resolving the contradiction between mechanical strength and extrusion capability through synergistic material combination.
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 composition effectively minimizes phase separation, maintains clarity, and enhances touch sensitivity while avoiding viscosity increases and gelation issues during processing, making it suitable for electronic devices.
Implementation Method 1
a crosslinked composition formed upon exposure of the crosslinkable composition to ultraviolet radiation or ionizing radiation
Data Source
AI summary
A crosslinkable composition, a crosslinked composition formed upon exposure of the crosslinkable composition to ultraviolet radiation or ionizing radiation, articles containing these crosslinkable or crosslinked compositions, and methods of making the articles are described. The crosslinkable compositions contain two different (meth)acrylate polymers and can be applied to a substrate using an extrusion process. While being extruded, the crosslinkable compositions advantageously are resistant to crosslinking and/or significantly increasing in molecular weight. The crosslinked compositions can function as either a pressure-sensitive adhesive composition or a heat bondable adhesive composition and are particularly well suited for use in electronic devices.