Polycarbonate Laminate Surface Hardness Impact Resistance
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Solution Overview
Problem
Display covers with aromatic polycarbonate resin bases have insufficient surface hardness and abrasion resistance, while those with acrylic resin bases lack impact resistance and punchability, and both are prone to yellowing due to ultraviolet light exposure, especially when used in thin thicknesses or as building materials.
Innovation Solution
A laminate structure comprising a specific polycarbonate resin layer with a dihydroxy compound-derived structural unit, combined with an aromatic polycarbonate resin, which enhances surface hardness and impact resistance, and incorporates a hardcoat layer for further durability, while minimizing the use of ultraviolet absorbers to prevent yellowing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an aromatic polycarbonate resin is used as the base material, then impact resistance and transparency are improved, but surface hardness and abrasion resistance deteriorate
Solution Approach 1:
The invention uses a composite laminate structure consisting of an aromatic polycarbonate resin layer and a polycarbonate resin layer with specific structural units. This composite structure combines the high impact resistance of aromatic polycarbonate with the superior surface hardness of the specific polycarbonate resin, achieving both properties simultaneously in the final product.
2Force
If an acrylic resin is used as the base material, then surface hardness and transparency are improved, but impact resistance and punchability deteriorate
Solution Approach 1:
The laminate structure replaces acrylic resin with a combination of aromatic polycarbonate resin and specific polycarbonate resin. This composite material provides both the required surface hardness (from the specific polycarbonate resin) and excellent impact resistance (from the aromatic polycarbonate), eliminating the need for acrylic resin while maintaining or improving both properties.
3Strength
If an aromatic polycarbonate resin is used, then impact resistance is improved, but yellowing deterioration occurs due to ultraviolet light absorption
Solution Approach 1:
The specific polycarbonate resin layer acts as an intermediary between the ultraviolet environment and the aromatic polycarbonate resin layer. This intermediate layer with specific structural units provides UV resistance and prevents yellowing, while allowing the aromatic polycarbonate layer to maintain its impact resistance properties.
4Length of stationary object
If the display cover thickness is reduced, then the product becomes thinner and more compact, but impact resistance and punchability deteriorate
Solution Approach 1:
The composite laminate structure enables thickness reduction while maintaining impact resistance. The synergistic combination of aromatic polycarbonate resin and specific polycarbonate resin with complementary properties allows the creation of thinner components that retain or improve mechanical strength compared to thicker single-material designs.
Data Source
AI summary
A laminate characterized by laminating a layer A of a polycarbonate resin which contains a structural unit derived from a dihydroxy compound and a structural unit other than the structural unit derived from said dihydroxy compound to a layer B of an aromatic polycarbonate resin, wherein the dihydroxy compound is a dihydroxy compound represented by the following formula (2), and wherein a content of the structural unit derived from the dihyroxy compound represented by the above formula (2) in the polycarbonate resin to be used for forming the layer A is 35% by mole or higher and 90% by mole or less.