Polyolefin Foam Adhesive Tape Bubble Structure
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Solution Overview
Problem
Adhesive tapes used in portable electronic devices face challenges in providing both good followability and impact resistance, especially with the increasing screen sizes of devices like smartphones and tablets, where they tend to separate easily upon impact.
Innovation Solution
An adhesive tape with a polyolefin foam base having specific bubble diameter ratios and interlaminar strength, ensuring excellent followability and impact resistance by preventing water and dust ingress and maintaining adhesion even under stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If adhesive tapes with small thicknesses are used to provide good followability, then the adhesive tapes can suitably be used for providing portable electronic devices with waterproofness, but the adhesive tapes become easily separated when an impact due to falling or the like is applied
Solution Approach 1:
The invention changes the physical parameters of the foam base by controlling the bubble diameter ratios in different directions. Specifically, it sets the ratio of average bubble diameter in the machine direction to vertical direction, and the ratio of average bubble diameter in the cross-machine direction to vertical direction, both at 6 or less. This parameter optimization enables the foam to achieve both thin profile for good followability and sufficient impact resistance
Solution Approach 2:
The invention uses a composite structure combining a polyolefin foam base with specific adhesive layers. The foam base provides cushioning and impact absorption, while the adhesive layers ensure strong bonding. This composite material approach allows the adhesive tape to simultaneously achieve good followability through the foam's compressibility and excellent impact resistance through the combined structure
2Adaptability or versatility
If the screen size of information display units is increased, then the degree of freedom of information display units is improved, but the adhesive tapes become easily separated when impact is applied
Solution Approach 1:
The foam base with controlled bubble structure provides beforehand cushioning against impact forces. The small bubble diameter ratios (6 or less) create a fine-cell structure that distributes impact energy throughout the foam, preventing sudden separation at the adhesive interface before damage occurs
3Adaptability or versatility
If adhesive tapes are used for fixing protective panels of information display units, then the degree of freedom is improved, but separation occurs when impact is applied
Solution Approach 1:
The invention optimizes the foam base parameters including bubble diameter ratios and interlaminar strength to maintain strong bonding under impact while preserving design flexibility for various screen sizes and configurations
Data Source
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AI summary
An adhesive tape includes a particular foam base. An average bubble diameter in a machine direction (MD) and an average bubble diameter in a cross-machine direction (CD) of the foam base are each 150 µm or less, a ratio represented by the average bubble diameter in the machine direction/an average bubble diameter in a vertical direction (VD) and a ratio represented by the average bubble diameter in the cross-machine direction/the average bubble diameter in the vertical direction are each 6 or less, and the foam base has an interlaminar strength of 20 N/cm or more. With this adhesive tape, good followability to an adherend and excellent impact resistance can be realized. Accordingly, the adhesive tape of the present invention can be suitably used in portable electronic devices such as smartphones, tablet personal computers, notebook personal computers, and game machines whose screen size has been increasing and for which a requirement for flexible design is high.