Polycarbonate Composition for Electrical Tracking Resistance
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Solution Overview
Problem
Polycarbonate compositions used in electrical applications face challenges in achieving a balance between flame retardancy, tracking resistance, and impact performance, particularly at low temperatures, as additives like impact modifiers can impair both tracking resistance and flame retardancy.
Innovation Solution
A composition comprising 7.5 to 25 wt% polysiloxane block co-polycarbonate, 5 to 15 wt% titanium dioxide, 2 to 30 wt% brominated organic flame retardant, and optionally 0.1 to 0.5 wt% fluorinated polyolefin, which provides a p(FTP) V0 flammability rating greater than 0.85 and resistance to electrical tracking through at least 50 drops of a 0.1% aqueous ammonium chloride solution at 250V.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If impact modifiers are added to improve impact resistance, then impact performance is improved, but tracking resistance deteriorates
Solution Approach 1:
The patent modifies the material composition by incorporating polysiloxane block co-polycarbonate at 7.5-25 wt% to enhance impact resistance, while simultaneously controlling the bromine content from flame retardants to be within 1-10 wt% to maintain tracking resistance, demonstrating parameter optimization to resolve the contradiction
2Strength
If impact modifiers are added to improve impact resistance, then impact performance is improved, but flame retardancy deteriorates
Solution Approach 1:
The patent develops a multi-component composite system where polysiloxane block co-polycarbonate provides impact enhancement while brominated flame retardants (1-10 wt% bromine) maintain flame retardancy, and the synergistic interaction between components allows simultaneous achievement of both properties that would be contradictory in simpler systems
Data Source
AI summary
This disclosure relates to polycarbonate compositions, methods, and articles of manufacture that at least meets certain electrical tracking resistance requirements. The compositions, methods, and articles of manufacture that meet these requirements contain at least a polycarbonate; a polysiloxane block co-polycarbonate; and a transition metal oxide, e.g. titanium dioxide.