Crosslinked Acrylic Adhesive Composition for Electronic Displays
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Solution Overview
Problem
Existing adhesive compositions for electronic displays face challenges in maintaining suitable optical, mechanical, and electrical properties over the lifetime of the display, particularly due to issues with viscosity and phase separation caused by the inclusion of hydroxy-containing monomers.
Innovation Solution
A crosslinkable composition comprising 50 to 95 weight percent of a first (meth)acrylate copolymer with a weight average molecular weight of 100,000 to 1,500,000 Daltons, and 5 to 50 weight percent of a second (meth)acrylate copolymer with a weight average molecular weight greater than 10,000 to less than 100,000 Daltons, which is exposed to ultraviolet radiation or ionizing radiation to form a crosslinked composition suitable for use as a pressure-sensitive or heat bondable adhesive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydroxy-containing monomers are included in adhesive compositions to improve adhesive properties and dielectric constant, then adhesive performance is improved, but viscosity increases and phase separation occurs
Solution Approach 1:
The adhesive composition is segmented into two distinct polymer components: a first polymer with low hydroxy content (0-10 wt%) providing structural stability and controlled viscosity, and a second polymer with high hydroxy content (15-70 wt%) providing adhesive properties and dielectric enhancement. This segmentation allows each component to fulfill its specific function without the negative effects of uncontrolled hydroxy content throughout the entire composition.
Solution Approach 2:
Different regions of the polymer structure have different hydroxy contents tailored to their specific functions. The first polymer region maintains low hydroxy content for viscosity stability, while the second polymer region contains high hydroxy content for adhesive performance. This local differentiation resolves the contradiction by allowing high hydroxy content where needed without compromising overall composition stability.
2Reliability
If hydroxy-containing monomers are included to enhance dielectric constant, then electrical properties are improved, but phase separation occurs in high humidity environments
Solution Approach 1:
The composition is divided into two polymer phases with different hydroxy contents. The first polymer (low hydroxy) acts as a stabilizing matrix that prevents phase separation, while the second polymer (high hydroxy) provides the necessary dielectric properties. This segmentation isolates the phase separation risk to only the high hydroxy region rather than affecting the entire composition.
Solution Approach 2:
The invention creates a composite adhesive system combining two polymers with complementary properties. The first polymer provides structural integrity and phase stability, while the second polymer contributes dielectric properties. The composite structure allows the material to maintain both high dielectric constant and resistance to phase separation simultaneously.
3Ease of manufacture
If single polymer adhesive compositions are used to simplify formulation, then manufacturing is easier, but optical clarity and stability deteriorate
Solution Approach 1:
The invention employs a two-polymer composite formulation that achieves superior optical clarity and stability compared to single-polymer systems. The first polymer (low hydroxy content) and second polymer (high hydroxy content) work synergistically to eliminate phase separation and maintain optical properties, justifying the slightly increased formulation complexity through significant performance gains.
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 crosslinked composition exhibits improved adhesive properties, enhanced dielectric constant, and reduced haziness, particularly in high humidity environments, while maintaining stability and optical clarity, making it well-suited for electronic devices.
Implementation Method 1
exposed to ultraviolet radiation or ionizing radiation to form a crosslinked composition
Implementation Method 2
exposed to ultraviolet radiation or ionizing radiation to form a crosslinked composition
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 compositions, and methods of making the articles are described. The crosslinkable compositions contain two different (meth)acrylate copolymers and can be applied to a substrate using an extrusion process. While being extruded, the crosslinkable compositions advantageously are resistant to crosslinking and/or increased molecular weights. The crosslinked compositions can function as adhesive compositions that are particularly well suited for use in electronic devices.