Structured Adhesive Liner for Bubble-Free Lamination
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Solution Overview
Problem
Existing methods for creating microstructured adhesive surfaces often introduce stresses during lamination, leading to defects in adhesive properties and optical quality due to the collapse of microstructured features, which can result in bubbles and pinholes in the bond line, especially when dealing with rigid substrates.
Innovation Solution
A multi-layer article comprising a substrate, a pressure-sensitive adhesive layer, and a liner with concave structures that are embossed together using a structured tool, allowing the structures to distort the liner and adhesive layer without distorting the substrate, and remain unstable until lamination, thereby minimizing stress and defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If applied pressure is used to collapse the microstructured features during lamination, then the adhesive bond is formed, but stresses are introduced into the adhesive creating defects that adversely affect adhesive and optical properties
Solution Approach 1:
The adhesive is pre-applied to the structured release liner, allowing the microstructured features to be formed in advance. This preliminary structuring enables the adhesive to be ready for lamination without requiring high pressure during the bonding process, thus preventing stress-induced defects while maintaining bond strength
Solution Approach 2:
The structured release liner serves as an intermediary tool that imparts the microstructured pattern to the adhesive. By using this mediator, the adhesive acquires the desired microstructure without direct application of high pressure, thereby avoiding stress concentration and defects in the final adhesive bond
2Reliability
If microstructured features are created in the adhesive surface, then air egress is improved minimizing bubbles and pinholes, but the microstructured features may flatten out and introduce stresses into the adhesive
Solution Approach 1:
The microstructured features are preliminarily formed in the adhesive by contacting it with a structured release liner before lamination. This advance structuring ensures air egress pathways are established while the adhesive is still in its uncured, flexible state, allowing the structures to form without introducing stresses that would occur if pressure were applied to collapse them during bonding
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
This approach ensures that the adhesive structures collapse spontaneously after lamination, reducing the need for applied pressure and heat, while maintaining adhesive strength and optical clarity by preventing air egress and minimizing bond line defects.
Implementation Method 1
applying pressure to the construction such that at least some of the structures on the surface of the tool distort the liner and the adhesive layer but does not distort the second major surface of the substrate. The distortion in the liner is retained upon release of the applied pressure.
Implementation Method 2
When the resulting articles are dry laminated under pressure to substrates such as glass or polymer films, the microstructured features created in the adhesive surface allow air to escape from the bonding interface, thereby minimizing or preventing the formation of bubbles and pinholes.
Data Source
AI summary
Methods of forming laminating adhesive articles include providing a multi-layer article, and a tool with a structured surface. The multi-layer articles include a substrate, an adhesive layer, and a liner or may just include an adhesive layer and a liner. The multi-layer article is placed between the structured surface of the tool and a support surface and the tool is embossed against the liner by applying pressure or a combination of pressure and heat. The embossing causes the structures on the surface of the tool to distort the liner and the adhesive layer but does not distort the substrate. The distortion in the liner is retained upon release of the applied pressure. Upon removal of the liner from the adhesive layer, the structures on the adhesive layer are unstable, but do not immediately collapse.