Pressure Sensitive Adhesive Sheet with Porous Void Layer for Blister Resistance
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Solution Overview
Problem
Existing pressure sensitive adhesive sheets face challenges in achieving both pressure sensitive characteristics and blister resistance when attached to plastic molded articles, with previous solutions being limited in cross-linking agents, molecular weight, and compatibility, leading to issues like blister formation and impaired appearance.
Innovation Solution
A pressure sensitive adhesive sheet with a laminated structure of a supporting substrate, a pressure sensitive adhesive layer, a continuous void-containing layer with fine particles, and another pressure sensitive adhesive layer, where the fine particles have a specific mass concentration and median diameter, facilitating gas escape and preventing blisters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure sensitive adhesive sheet with gas barrier property is attached to a plastic molded article, then adhesion is achieved, but gas generated from the plastic molded article forms bubbles causing blister
Solution Approach 1:
The invention introduces a porous layer containing fine particles (such as silica, alumina, or boehmite) with specific surface areas (5-200 m²/g) between the adhesive layer and the plastic molded article. This porous structure provides gas permeability that allows generated gas to escape, preventing blister formation while maintaining adhesion functionality.
Solution Approach 2:
The porous layer acts as an intermediary between the adhesive layer and the plastic molded article. It mediates the interaction by providing a pathway for gas escape while maintaining the bonding function, thus resolving the conflict between adhesion and blister prevention.
2Reliability
If a cross-linking agent is added to improve blister resistance, then gas barrier property is enhanced, but cohesive strength of the adhesive layer is impaired
Solution Approach 1:
The invention segments the functional layers: the adhesive layer maintains its cohesive strength without excessive cross-linking, while the porous layer (separate functional segment) provides the gas escape pathway. This segmentation allows each layer to optimize its specific function without compromising the other.
Solution Approach 2:
The porous layer serves as an intermediary that handles the gas escape function, allowing the adhesive layer to focus on maintaining cohesive strength and adhesion without being overloaded with cross-linking agents that would compromise its integrity.
3Reliability
If a curing component is added to the adhesive layer, then blister resistance is improved, but the adhesive layer becomes cloudy due to poor compatibility
Solution Approach 1:
The invention uses a porous layer with fine particles instead of adding curing components to the adhesive layer. This porous structure provides gas permeability for blister prevention while maintaining the transparency and compatibility of the adhesive layer, as no incompatible curing agents are introduced.
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 sheet exhibits excellent blister resistance and a smooth surface, suitable for various adhesives, while maintaining a high-quality appearance and ease of production.
Implementation Method 1
a continuous void-containing layer containing a composition containing fine particles (excepting silica) with a median diameter of from 0.001 to 100 μm, the mass concentration of the fine particles in the continuous void-containing layer being from 45 to 100%
Data Source
Figure 1~3
AI summary
The present invention relates to a pressure sensitive adhesive sheet containing, laminated in this order, a supporting substrate, a pressure sensitive adhesive layer (X), a continuous void-containing layer including a composition containing fine particles (excepting silica), and a pressure sensitive adhesive layer (Y), the continuous void-containing layer having a mass concentration of the fine particles of from 45 to 100%.