Stretchable Film Surface Topography to Prevent Layer Cracking
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Solution Overview
Problem
Existing stretchable films used in biosensors and deformable image display devices suffer from cracks or fractures in functional layers due to lack of elasticity, and incorporating particles can lead to haze or particle loss when stretched.
Innovation Solution
A stretchable film with an uneven shape on at least one surface, exhibiting ≥20% tensile elongation in two perpendicular directions, with controlled surface roughness changes and convex portion distribution to maintain functionality during stretching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an anti-glare layer, anti-reflection layer, or hard coat layer is formed on a stretchable film, then the film gains protective or functional properties, but the layers crack or fracture when the film is stretched
Solution Approach 1:
The patent changes the physical-chemical parameters of the base material by incorporating elastomers or waxes to create a stretchable film that can elongate by 20% or more. This parameter change allows the film to stretch without causing functional layers to crack, resolving the contradiction between providing protective layers and maintaining their integrity during stretching.
Solution Approach 2:
The patent creates a composite material system consisting of a base material combined with elastomers or waxes. This composite structure provides both the stretchability needed to prevent layer cracking and the stability required to maintain functional layer adhesion, thus resolving the contradiction between layer integrity and stretchability.
2Adaptability or versatility
If particles are incorporated into the resin to impart anti-glare properties, then the resin itself becomes stretchable with anti-glare function, but particles fall off when stretched or haze increases making images difficult to see
Solution Approach 1:
The patent extracts the anti-glare function from the particle phase and transfers it to the continuous resin phase by forming an uneven shape on the resin surface. This eliminates particles from the system, preventing particle loss during stretching while maintaining anti-glare properties and image clarity.
Solution Approach 2:
The patent replaces the mechanical particle-based anti-glare system with a surface topography-based anti-glare system. The uneven shape on the resin surface provides anti-glare functionality without requiring embedded particles, thus eliminating particle loss and haze issues while maintaining stretchability.
Data Source
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AI summary
To provide a stretchable film that can be stretched and used without a reduction in the function of the film itself or the layers formed on the film. A stretchable film having an uneven shape on at least one surface, wherein a tensile elongation at break in a first direction in a plane of the film is more than 20%, the tensile elongation at break in a second direction perpendicular to the first direction is more than 20%, and when a 0.44 mm square area is observed using a white light interference microscope, and a surface roughness measured before stretch is defined as Sa(0), the surface roughness measured after 20% stretch in the first direction is defined as Sa1(20), and the surface roughness measured after 20% stretch in the second direction is defined as Sa2(20), a rate of change in surface roughness in the first direction, ΔSa1, is -15.0% or less, and the rate of change in surface roughness in the second direction, ΔSa2, is -15.0% or less.