Laminated Resin Sheet Hard Coating for Scratch-Resistant Molding
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Solution Overview
Problem
Polycarbonate resin molded products lack sufficient surface hardness, leading to easy scratching and limiting their application in devices requiring high surface durability, such as small portable devices and touch panel-type display surfaces.
Innovation Solution
A laminated resin sheet comprising a high-hardness resin layer, a polycarbonate resin base material layer, and a hard coat layer with specific properties, including a Martens hardness of 100 to 250 N/mm² and elastic deformation of 40% to 64%, enhances scratch resistance and adhesion while maintaining moldability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polycarbonate resin molded product is used, then transparency, lightness and impact resistance are improved, but surface hardness is insufficient and the product is easily scratched
Solution Approach 1:
The invention uses a composite structure consisting of a polycarbonate resin base material layer and a hard coat layer with different properties. The base material layer provides impact resistance and transparency, while the hard coat layer provides surface hardness and scratch resistance. This composite material approach resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The invention segments the molded product into two distinct functional layers: a base material layer for structural integrity and impact resistance, and a hard coat layer for surface protection. This segmentation allows each layer to optimize its specific function without compromising the other, addressing the contradiction between impact resistance and scratch resistance.
2Object-affected harmful factors
If a hard coat layer is applied to increase surface hardness, then scratch resistance is improved, but adhesion to the base material may deteriorate
Solution Approach 1:
The invention optimizes the Martens hardness parameter of the hard coat layer to a specific range (100-250 N/mm²) and controls the elastic deformation (40-64%). By adjusting these parameters within optimal ranges, the hard coat layer achieves both scratch resistance and adequate adhesion to the base material, resolving the contradiction between hardness and adhesion.
Solution Approach 2:
The invention creates local quality differentiation within the hard coat layer by controlling its specific hardness and elastic deformation properties. This localized optimization ensures that the surface has sufficient hardness for scratch resistance while maintaining appropriate adhesion characteristics at the interface with the base material.
3Object-affected harmful factors
If the hard coat layer has high Martens hardness for scratch resistance, then surface durability is improved, but appearance abnormalities during molding may increase
Solution Approach 1:
The invention identifies and controls critical parameters including Martens hardness (100-250 N/mm²), elastic deformation (40-64%), and thickness ratios between layers. By optimizing these parameters within specific ranges, the hard coat layer achieves scratch resistance while minimizing appearance abnormalities such as cracking or delamination during the molding process.
Solution Approach 2:
The invention performs preliminary optimization of the hard coat layer properties before the molding process. By pre-establishing the appropriate hardness, elastic deformation, and thickness parameters, the material is prepared in advance to withstand the molding process without developing appearance defects, thus preventing rather than correcting problems.
Data Source
Figure 1
AI summary
According to the present invention, there can be provided a laminated resin sheet for molding, comprising: a high-hardness resin layer comprising a high-hardness resin, a base material layer comprising a polycarbonate resin (a1), disposed on one side of the high-hardness resin layer and a hard coat layer, disposed on the other side of the high-hardness resin layer, wherein the hard coat layer has a Martens hardness of 100 to 250 (N/mm2) and an elastic deformation percentage of 40% to 64%, the hard coat layer consists of a hard coating composition, comprising: (A) a 2 to 15 functional (meth)acrylate oligomer, (B) a 1 or 2 functional (meth)acrylate monomer, having a molecular weight of less than 200 and a viscosity at 25°C of 15 cps or less, (C) a photopolymerization initiator, (D) a surface modifier, and (E) a hue improver, and the content of the hue improver (E) is 0.002 to 0.020 parts by mass, with respect to 100 parts by mass of a total of the component (A) and the component (B).