Adhesive Sheet with High Tensile Strength for Thin Electronics
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Solution Overview
Problem
Adhesive sheets used in electronic devices and automotive applications face challenges in achieving excellent peel adhesion, push strength, holding power under static load, and impact resistance, particularly as devices become thinner and larger, requiring narrower adhesive applications.
Innovation Solution
An adhesive sheet with an adhesive layer having a tensile strength of 6 N/cm2 or more, combined with a foam substrate of specific bubble diameters and ratios, provides excellent peel adhesion, push strength, holding power under static load, and impact resistance without compromising other properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If adhesive sheets are used in thinner and larger electronic devices with reduced application areas, then device thickness is reduced and screen size is increased, but peel adhesion and push strength deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive layer by incorporating specific monomers (carboxyl group-containing monomer at 0.1-10 mass%, hydroxyl group-containing monomer at 0.1-10 mass%) and crosslinking agents. This chemical parameter modification enables the adhesive to maintain high peel adhesion and push strength even when applied in reduced areas on thinner devices.
Solution Approach 2:
The adhesive layer is formulated as a composite material system comprising multiple polymer components (polymer 1 and polymer 2 with specific weight ratios), crosslinking agents, and functional monomers. This composite structure provides synergistic effects that enhance both peel adhesion and push strength, allowing the adhesive to perform reliably in thin-device applications where application area is limited.
2Strength
If adhesive sheets are designed for better peel adhesion, then peel adhesion is improved, but push strength and holding power under static load deteriorate
Solution Approach 1:
The patent optimizes the weight ratio parameters between polymer 1 and polymer 2, and controls the concentrations of crosslinking agents and functional monomers within specific ranges. These parameter adjustments create a balanced adhesive formulation that simultaneously achieves high peel adhesion (through functional group interactions) and reliable push strength/holding power (through crosslinked network structure).
Solution Approach 2:
The adhesive layer exhibits different local properties: the functional monomers (carboxyl and hydroxyl groups) provide localized high adhesion to substrates, while the crosslinked polymer matrix provides localized structural integrity and resistance to push forces. This spatial differentiation of functions within the adhesive layer resolves the contradiction between peel adhesion and push strength.
3Volume of moving object
If adhesive sheets are applied in narrower widths for thin devices, then device thickness is reduced, but impact resistance deteriorates
Solution Approach 1:
The patent modifies the adhesive composition parameters including the addition of hydroxyl group-containing monomers and crosslinking agents, which create a more robust crosslinked network structure. This structural reinforcement enables the adhesive to maintain high impact resistance even when applied in narrower widths on thin devices.
Solution Approach 2:
The adhesive forms a composite material system with crosslinked polymer networks that provide enhanced toughness and impact resistance. This composite structure compensates for the reduced application width by creating a more resilient adhesive layer that can absorb impact energy effectively.
Data Source
AI summary
An object to be achieved by the present invention is to provide an industrially useful adhesive sheet that can be used to bond various adherends and has excellent peel adhesion, excellent push strength, and excellent holding power under static load. The object of the present invention can be achieved by an adhesive sheet having, on one side or both side of a substrate, an adhesive layer (A) having a tensile strength of 6 N/cm2 or more as determined from a stress-strain curve (a so-called S-S curve) at a strain of 100%.