(Meth)acrylic-Epoxy UV Adhesive Impact Resistance
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Solution Overview
Problem
Existing adhesives used in electronic devices and other industrial applications lack sufficient impact and drop resistance, especially under traumatic forces such as drops onto hard surfaces.
Innovation Solution
A curable composition comprising a (meth)acrylic-based multiblock copolymer, a random (meth)acrylate copolymer with pendant poly(alkylene oxide) groups, an epoxy resin, and a cationic photoinitiator, which forms a semi-structural or structural adhesive with enhanced tensile and shear impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional adhesives are used to bond components in mobile electronic devices, then adhesion is maintained under normal conditions, but impact and drop resistance is insufficient when subjected to traumatic forces
Solution Approach 1:
The patent employs a composite adhesive formulation combining multiple polymer components: a polyether component providing toughness and impact resistance, and a (meth)acrylic component providing adhesion and structural strength. This composite material approach allows the adhesive to simultaneously achieve both impact resistance and reliable adhesion under traumatic forces, resolving the contradiction between these two performance requirements
2Ease of operation
If the adhesive is made softer to improve wet out during assembly, then bonding performance improves, but storage stability and ooze resistance deteriorate at room temperature
Solution Approach 1:
The patent utilizes the glass transition temperature (Tg) as a critical parameter to control adhesive behavior. The polyether component is selected with a Tg below -50°C to ensure softness and good wet out during assembly at room temperature, while the overall composition is designed to maintain structural integrity and prevent excessive ooze during storage. This parameter-based approach resolves the contradiction between operational softness and storage stability
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 cured adhesive composition demonstrates improved tensile and shear impact resistance, maintaining adhesion under normal conditions and during exposure to traumatic forces, making it suitable for use in mobile electronic devices and other applications.
Implementation Method 1
The curable compositions provided herein have sufficiently long open times to achieve good adhesive characteristics when tested as fully bonded adhesive-substrate laminates. The combination of good die-cut stability and sufficiently long open times can be achieved, at least in part, by preparation of a curable composition that includes a polyether component that can be incorporated into the cured polymeric network.
Data Source
AI summary
Curable and cured compositions as well as articles that contain the curable or cured compositions are provided. The curable composition comprises (a) a (meth)acrylic-based multiblock copolymer, (b) a random (meth)acylate copolymer comprising a monomeric unit having a pendant poly(alkylene oxide) group, wherein the monomeric unit having the pendant poly(alkylene oxide) group has a number average molecular weight of at least 300 Daltons, (c) an epoxy resin, and (d) a cationic photoinitiator. Articles containing the curable composition can be die-cut and can retain their dimensions with minimal oozing when stored under ambient conditions.