PSA Sheet Hardness Controls Adhesive Aging on Glass
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Solution Overview
Problem
The adhesive strength of pressure-sensitive adhesive (PSA) sheets used for protecting glass plates with Low-E layers increases over time, making it difficult to efficiently remove them, especially from large surface areas, which can lead to heavy peeling and reduced efficiency in the production process.
Innovation Solution
A method involving a PSA sheet with a substrate layer and a PSA layer having a surface hardness of 0.3 MPa or greater, which is applied to the glass plate and can be efficiently removed without compromising the protection of the Low-E layer, even after exposure to processes like washing, by controlling the aged adhesive strength through mechanical properties characterized by nanoindentation measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PSA sheet is applied to protect glass plate surface, then protection effect is improved, but adhesive strength increases with aging making removal difficult
Solution Approach 1:
The patent applies parameter changes by controlling the glass transition temperature (Tg) of the PSA within a specific range (-50°C to 0°C) and adjusting the adhesive layer thickness (3μm to 10μm) to optimize the balance between initial adhesion and aged adhesive strength. This allows the PSA to provide adequate protection while maintaining removal efficiency even after aging.
2Productivity
If glass plate surface area is enlarged for production efficiency, then productivity is improved, but aged adhesive strength increases leading to heavy peeling
Solution Approach 1:
The patent resolves this contradiction by changing the physical parameters of the PSA, specifically setting the glass transition temperature between -50°C and 0°C and controlling the adhesive layer thickness between 3μm and 10μm. These parameter adjustments ensure that even on large surface area glass plates (greater than 2.6m width), the aged adhesive strength remains controlled and does not cause heavy peeling, thereby maintaining both productivity and removal efficiency.
3Reliability
If PSA adhesive strength is increased for better protection, then reliability is improved, but removal becomes difficult and efficiency decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the glass transition temperature of the PSA within -50°C to 0°C and the adhesive layer thickness within 3μm to 10μm. This creates an optimal balance where the PSA provides sufficient adhesive strength for reliable protection during transportation and handling, yet maintains easy removability without requiring excessive force or time, thus preserving productivity.
Data Source
AI summary
Provided is a method for producing a glass unit. The method comprises a step (A) of obtaining a glass plate; a step (B) of applying a protective sheet to one face of the glass plate; an optional step (C) of subjecting the glass plate to at least one process selected from the group consisting of transportation, storage, processing, washing and handling; a step (D) of removing the protective sheet from the glass plate; and a step (E) of assembling a glass unit using the glass plate. The protective sheet comprises a substrate layer, and a PSA layer provided to at least one face of the substrate layer. The PSA layer has a surface hardness of 0.3 MPa or greater.