Flame-Retardant Insulating Sheet Surface Texture to Prevent Sticking
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Solution Overview
Problem
Flame-retardant insulating sheets used in electrical/electronic devices often suffer from sticking issues when stacked or stored, which deteriorates handleability and can lead to breakage. Existing solutions do not effectively address this problem.
Innovation Solution
A flame-retardant insulating sheet containing a polycarbonate resin and a nitrogen-containing flame retardant, such as melamine cyanurate, with specific surface characteristics: an arithmetic mean peak curvature (Spc) of 200 (1/mm) or more, a peak density (Spd) of 8,000 (1/mm2) or more, and a 60° glossiness of 25 or less on at least one surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flame retardants such as ammonium polyphosphate or phosphate ester compounds are blended with polycarbonate resin, then flame retardancy is improved, but heat resistance and mechanical characteristics become insufficient
Solution Approach 1:
The patent changes the chemical composition parameter by using a nitrogen-containing flame retardant (5-30 mass% based on total resin weight) instead of conventional phosphorus-based flame retardants. This parameter change maintains flame retardancy while preserving the heat resistance and mechanical properties of the polycarbonate resin, as the nitrogen-containing compound does not compromise the resin's thermal and structural integrity.
Solution Approach 2:
The patent creates a composite material system consisting of polycarbonate resin combined with nitrogen-containing flame retardant particles. This composite approach allows the flame retardant to function effectively without forming a homogeneous mixture that would compromise the resin's base properties, thereby maintaining both flame retardancy and mechanical strength.
2Reliability
If a large amount of brominated bisphenol A carbonate derivative is blended to improve flame retardancy, then flame retardancy is improved, but impact resistance is lowered and breakage becomes likely
Solution Approach 1:
The patent changes the flame retardant type parameter from halogen-based compounds to nitrogen-containing compounds. This substitution eliminates the harmful effect on impact resistance while maintaining effective flame retardancy, as the nitrogen-containing compound does not interfere with the polycarbonate resin's molecular structure and toughness.
3Productivity
If resin sheets are stacked and stored, then storage efficiency is improved, but sticking occurs and handleability deteriorates
Solution Approach 1:
The patent applies a roughening treatment to only the surface of the insulating sheet that contacts other sheets during stacking, while keeping the opposite surface smooth. This localized surface modification prevents sticking between stacked sheets without affecting the overall quality or electrical insulation properties of the material, thereby maintaining both storage efficiency and handleability.
Data Source
AI summary
The present invention provides a flame-retardant insulating sheet containing a polycarbonate resin and a flame retardant, in which the flame retardant includes a nitrogen-containing compound, and on at least one surface of the flame-retardant insulating sheet, an arithmetic mean peak curvature (Sp) is 200 (1/mm) or more, a peak density (Spd) is 8,000 (1/mm2) or more, or a 60° glossiness is 25 or less. An electrical/electronic device using the flame-retardant insulating sheet.