Volume Hologram Sheet Adhesion for Stress Resistance
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Solution Overview
Problem
Existing volume hologram sheets face challenges in providing sufficient mechanical stress resistance during processing under heating conditions, leading to issues like exfoliation, bubble generation, and surface ruggedness when integrated into paper or card media.
Innovation Solution
A thin volume hologram sheet configuration with a volume hologram layer and a substrate disposed on one side, achieving a peeling strength of 25 gf/25 mm or more using an adhesion means, such as an adhesive layer or chemical process with a primer agent, to enhance resistance to tensile, shear, and compression stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a volume hologram sheet with two protection layers is used to provide mechanical stress resistance, then the resistance to tensile stress and shear stress under heating condition is improved, but the film thickness becomes bulky causing surface ruggedness
Solution Approach 1:
The invention divides the protection function into two segments: a thin substrate layer (6-25 μm) providing dimensional stability and a volume hologram layer (1-20 μm) providing mechanical stress resistance. This segmentation allows each layer to be optimized for its specific function, achieving sufficient strength while maintaining thin overall thickness and smooth surface.
Solution Approach 2:
The invention applies different properties to different parts of the structure: the substrate is designed with high dimensional stability and smooth surface properties, while the volume hologram layer is designed with high mechanical stress resistance. This local differentiation allows the thin film structure to achieve both smooth surface appearance and sufficient strength.
2Shape
If the volume hologram sheet is made thinner to achieve smooth surface, then the surface ruggedness is reduced, but the resistance to mechanical stress under heating condition deteriorates
Solution Approach 1:
The protection function is segmented between the substrate and volume hologram layer, allowing the substrate to be very thin (6-25 μm) for surface smoothness while the volume hologram layer provides the necessary mechanical stress resistance. This segmentation resolves the contradiction between thickness and strength.
Solution Approach 2:
The invention uses a composite structure combining a substrate made of dimensionally stable material with a volume hologram layer made of mechanically strong material. This composite approach allows the thin film to achieve both surface smoothness and mechanical stress resistance through the synergistic combination of different materials.
3Reliability
If the volume hologram layer and substrate are bonded with strong adhesion to prevent exfoliation and bubble generation, then the reliability during processing is improved, but the device complexity increases
Solution Approach 1:
The invention optimizes the peeling strength parameter to a specific range (15-30 gf/25mm) to ensure reliable bonding without excessive complexity. By carefully controlling this parameter through material selection and layer design, the invention achieves high processing reliability while maintaining a simple two-layer structure without requiring complex multi-layer configurations.
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 solution ensures a smooth surface integration and prevents exfoliation, bubble generation, and displacement during processing, providing a high forgery prevention effect and maintaining design integrity.
Implementation Method 1
a peeling strength of the volume hologram layer and the substrate is 25 gf/25 mm or more
Implementation Method 2
the volume hologram has a hologram image recorded by providing three-dimensionally in the thickness direction interference fringes generated by interference of a light as fringes of different refractive indices
Implementation Method 3
resistance to a mechanical stress such as a tensile stress, a shear stress and a compression stress at the time of processing even under a heating condition
Data Source
AI summary
An object of the present invention is to provide a thin volume hologram sheet to be embedded sufficiently resistant to a mechanical stress such as a stress including a tensile stress, a shear stress and a compression stress at the time of processing even under a heating condition, a forgery prevention paper and a card using the same. The object is achieved by providing a volume hologram sheet to be embedded comprising a volume hologram layer, and a substrate disposed only on one side surface of the volume hologram layer using an adhesion means, wherein a peeling strength of the volume hologram layer and the substrate is 25 gf/25 mm or more.