Pressure-Sensitive Adhesive Sheet Outgassing Bubble Prevention
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Solution Overview
Problem
Conventional pressure-sensitive adhesive (PSA) sheets face challenges in preventing bubble formation due to outgassing from adherends, as the PSA layer's grooves can shrink and lose effectiveness over time, especially with aging and increased temperature, leading to reduced adhesive strength and undesirable appearance.
Innovation Solution
A PSA sheet with a percent post-aging non-bonding area of 5% or higher, featuring linearly extending non-bonding areas on the adhesive face, which act as outgassing pathways to inhibit bubble formation, and optionally a coating layer to enhance air release properties, is designed to maintain effective adhesion and prevent bubble growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If grooves are formed in the PSA layer surface using ridges on the release liner, then air release properties are improved during application, but the grooves shrink and lose effectiveness over time due to PSA flow, reducing reliability for preventing outgassing bubbles
Solution Approach 1:
The patent introduces a release liner with a patterned surface that transfers grooves to the PSA layer during lamination. This preliminary action creates the groove structure before the PSA is applied to the adherend, ensuring the grooves are formed when the PSA is still pliable and can maintain their shape for bubble prevention during aging
Solution Approach 2:
The release liner acts as an intermediary tool that temporarily holds the groove pattern and transfers it to the PSA layer. This intermediary enables the creation of precise groove structures without directly modifying the PSA after application, maintaining both air release properties and long-term reliability
2Strength
If the PSA layer is made to flow easily with aging and temperature increase, then adhesion to the adherend is improved, but the grooves shrink and lose their shape, reducing effectiveness in preventing outgassing bubbles
Solution Approach 1:
The groove pattern is established in advance during the lamination process using the release liner as a mold. This preliminary formation of grooves occurs before the PSA undergoes significant aging or temperature increases that would cause flow, ensuring the grooves are created when the material is most workable and can maintain their structural integrity
Solution Approach 2:
The patent utilizes the temperature and pressure parameters during lamination to temporarily increase PSA flowability for groove formation, then allows the material to return to its original state where it maintains both adhesion strength and groove shape. The controlled application of thermal and mechanical parameters enables shape modification without permanent deformation
Data Source
AI summary
Provided is a PSA sheet capable of suitably preventing bubble formation caused by outgassing. This invention provides a PSA sheet comprising a PSA layer that forms an adhesive face. In an aging test where the adhesive face is press-bonded to a glass plate and stored at 50° C. for 24 hours, the PSA sheet has at least 5% post-aging non-bonding area Sa, with Sa defined as the ratio of all areas non-bonding to the glass plate relative to the total area of the adhesive face. The non-bonding areas have parts linearly extending along the adhesive face.