Cosmetic sheet, cosmetic material, and method for producing cosmetic sheet
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Solution Overview
Problem
Decorative sheets with formed projections and recesses are prone to scratches under external load, as existing technologies do not adequately enhance scratch resistance while maintaining designability.
Innovation Solution
A decorative sheet comprising a thermoplastic resin substrate layer, a transparent thermoplastic resin layer, and a surface protective layer with an outermost layer containing a multifunctional hexamethylene diisocyanate oligomer at a weight ratio of 60% or more, where the arithmetic mean height of the profile curve is 15 µm or more and the maximum height is 38 µm or more, improving hardness and reducing contact area under external load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If projections and recesses are formed on the surface of the decorative sheet for improving designability, then designability is improved, but scratches are likely to occur under external load
Solution Approach 1:
The patent applies local quality by creating projections and recesses only in the outermost layer of the surface protective coating, while the underlying primer layer and thermoplastic resin layer remain substantially flat. This localized surface structuring improves designability without compromising the overall structural integrity and scratch resistance provided by the bulk material layers.
Solution Approach 2:
The patent employs a composite structure consisting of multiple layers with different functions: a thermoplastic resin substrate layer providing structural strength, a surface protective layer offering surface hardness and chemical resistance, and an outermost layer with projections and recesses providing designability. The combination of these materials and structures allows simultaneous achievement of designability and scratch resistance.
2Ease of manufacture
If the surface protective layer is formed with a single layer structure, then the manufacturing process is simple, but the scratch resistance is insufficient
Solution Approach 1:
The surface protective layer is segmented into multiple functional sub-layers: a primer layer providing adhesion and corrosion resistance, and an outermost layer providing surface hardness and designability. This segmentation allows each layer to be optimized for its specific function while maintaining a relatively simple overall manufacturing process through sequential coating operations.
3Reliability
If the outermost layer contains high concentration of multifunctional hexamethylene diisocyanate oligomer (60% or more), then the hardness and scratch resistance are improved, but the adhesion to substrate may be compromised
Solution Approach 1:
The primer layer is applied first to the thermoplastic resin substrate layer before applying the outermost layer containing the multifunctional hexamethylene diisocyanate oligomer. This preliminary action ensures that the substrate surface is pre-treated with adhesion-promoting properties, allowing the subsequent high-concentration oligomer layer to achieve both hardness and adequate adhesion without direct contact with the substrate.
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 significantly enhances scratch resistance on the decorative sheet, reducing the occurrence of scratches and maintaining design integrity even with projections and recesses, while ensuring improved adhesion and bending processability.
Implementation Method 1
an outermost layer that is a layer located furthest from the transparent thermoplastic resin layer among layers constituting the surface protective layer contains an ionizing radiation-curable resin containing a multifunctional hexamethylene diisocyanate oligomer
Data Source
Figure 1~2
AI summary
There is provided a decorative sheet, a decorative material, and a method of producing a decorative sheet, which can suppress occurrence of scratches even when projections and recesses are formed on the surface of the decorative sheet. A decorative sheet (10) according to the present embodiment is a decorative sheet that includes at least a thermoplastic resin substrate layer (1), a transparent thermoplastic resin layer (4) and a surface protective layer (7) in this order. The surface protective layer (7) is formed by laminating at least two layers. At least a second surface protective layer (6), which constitutes an outermost layer that is a layer located furthest from the transparent thermoplastic resin layer (4) among layers constituting the surface protective layer (7), contains an ionizing radiation-curable resin containing a multifunctional hexamethylene diisocyanate oligomer at a weight ratio of 60% or more. The arithmetic mean height of a profile curve measured from the second surface protective layer (6) in accordance with JIS B 0601 is 15 µm or more, and the maximum height of the profile curve is 38 µm or more.