Polycarbonate Resin Composition for Heat Resistance and Transparency
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Solution Overview
Problem
Blending bisphenol A type and bisphenol AP type polycarbonate resins results in inferior processability and clouding, compromising heat resistance and transparency in formed articles.
Innovation Solution
A resin composition with specific viscosity average molecular weights and intrinsic viscosity differences between bisphenol AP and bisphenol A type polycarbonate resins, within defined ranges, to enhance formability, heat resistance, and transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If bisphenol A type polycarbonate resin and bisphenol AP type polycarbonate resin are blended to impart heat resistance, then heat resistance is improved, but processability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the viscosity average molecular weights of both polycarbonate resins and their blending ratio. Specifically, it specifies that the bisphenol A type polycarbonate resin should have a viscosity average molecular weight of 25,000-35,000 and the bisphenol AP type should have 18,500-23,000, with a mass ratio of 90/10 to 50/50. This parameter optimization resolves the contradiction by achieving the right balance between heat resistance (from bisphenol AP content) and processability (maintained through molecular weight control)
Solution Approach 2:
The patent employs composite materials by creating a blended resin composition from two different polycarbonate types. The composite structure combines the heat resistance properties of bisphenol AP type polycarbonate with the processability advantages of bisphenol A type polycarbonate, achieving a material that exhibits both desired properties simultaneously
2Temperature
If bisphenol A type polycarbonate resin and bisphenol AP type polycarbonate resin are blended, then heat resistance is improved, but transparency deteriorates (clouding occurs)
Solution Approach 1:
The patent resolves the transparency issue through parameter changes by controlling the molecular weight parameters and their difference. It specifies that the absolute difference in intrinsic viscosity between the two resins should be 0.04-0.18 dL/g. This precise parameter control ensures compatible molecular dimensions that prevent phase separation and clouding, while still allowing the heat resistance benefits of blending
3Temperature
If the intrinsic viscosity difference between bisphenol AP type and bisphenol A type polycarbonate resins is large, then heat resistance is improved, but compatibility deteriorates resulting in clouding
Solution Approach 1:
The patent applies parameter changes by establishing an optimal range for the intrinsic viscosity difference (0.04-0.18 dL/g). This parameter optimization ensures that the molecular size difference between the two polycarbonate types is sufficient to maintain heat resistance through bisphenol AP content, while remaining small enough to ensure compatibility and prevent clouding
Data Source
AI summary
Provided a resin composition that is excellent in formability, and is also excellent in heat resistance and transparency when made into a formed article, as well as a formed article using the resin composition. The resin composition of the present invention contains a bisphenol AP type polycarbonate resin having a viscosity average molecular weight of 18,500 to 23,000; and a bisphenol A type polycarbonate resin having a viscosity average molecular weight of 25,000 to 35,000, wherein the ratio (WAP/WA) of the mass (WAP) of the bisphenol AP type polycarbonate resin to the mass (WA) of the bisphenol A type polycarbonate resin is 20/80 to 90/10, and the difference (|ηA - ηAP|) between the intrinsic viscosity (ηAP) of the bisphenol AP type polycarbonate resin and the intrinsic viscosity (ηA) of the bisphenol A type polycarbonate resin is 0.04 to 0.18 dL/g.