Transparent Polyester Polycarbonate Blend for Low Haze
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Solution Overview
Problem
Developing polyester polycarbonate compositions that maintain high transparency and low haze while also providing good mechanical, weatherability, barrier, and chemical resistance properties has been challenging due to the adverse effects of blending polyesters with polycarbonates on optical properties.
Innovation Solution
A composition comprising specific ratios of polyester-polycarbonate polymer, first polyester, and second polyester, including isophthalate terephthalate resorcinol ester units and carbonate units, cyclohexane dicarboxylic acid-derived units, and isophthalic acid-derived units, which are miscible and extrudable to produce transparent pellets with low haze and high luminous transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyesters are blended with polycarbonates to improve mechanical properties and rheological properties, then impact strength and melt volume rate are improved, but optical properties deteriorate with hazy appearance and diminished light transmittance
Solution Approach 1:
The patent changes the chemical structure parameters of the polyester components by introducing specific aromatic groups (isophthalate, terephthalate, resorcinol ester) and controlling the ratio of different polyester units. This parameter change achieves miscibility with polycarbonate while maintaining optical clarity, resolving the contradiction between mechanical property improvement and light transmittance preservation
Solution Approach 2:
The patent creates a ternary composite material system combining polyester-polycarbonate polymer, first polyester, and second polyester in specific ratios. This composite approach allows the blend to achieve both improved mechanical properties from polycarbonate content and good optical properties from the miscible polyester components, simultaneously addressing both requirements
2Productivity
If polyesters are blended with polycarbonates to improve rheological properties, then melt volume rate is improved, but optical properties deteriorate with hazy appearance
Solution Approach 1:
The patent modifies the rheological parameters of the blend by selecting specific polyester types with appropriate molecular weights and structural characteristics. The isophthalate-terephthalate-resorcinol ester units provide good flow properties while the aromatic structure maintains optical clarity, achieving both improved melt volume rate and light transmittance
3Illumination intensity
If miscible blends of polyesters and polycarbonates are developed to provide good optical properties, then haze is reduced, but other advantageous properties such as weatherability and barrier resistance may be compromised
Solution Approach 1:
The patent creates a multi-component composite where each component contributes specific properties: the polyester-polycarbonate polymer provides baseline performance, the first polyester (cyclohexane dicarboxylic acid-derived) enhances weatherability and barrier properties, and the second polyester (isophthalic acid-derived) maintains miscibility and optical properties. This composite structure achieves both optical clarity and improved reliability
Solution Approach 2:
The patent assigns different functional roles to different components of the blend: the cyclohexane-containing polyester specifically targets weatherability and barrier performance, while the isophthalate-containing polyester focuses on miscibility and optical properties. This local quality differentiation allows the overall composition to achieve multiple performance goals simultaneously
Data Source
AI summary
A composition comprises a polyester-polycarbonate polymer comprising isophthalate-terephthalate-resorcinol ester units and carbonate units, a first polyester comprising repeating units derived from cyclohexane dicarboxylic acid or a chemical equivalent thereof, and a C2-8 aliphatic diol or a chemical equivalent thereof, and a second polyester comprising units derived from isophthalic and/or terephthalic acid and a chemical equivalent thereof, and a C2-8 aliphatic diol or a chemical equivalent thereof. The composition can be extruded into pellets that are clear and colorless. The composition can further be molded into articles having a percent haze value less than or equal to 10 percent, and total luminous transmittance value of greater than or equal to 70 percent, measured in accordance with ASTM D1003-00. Also disclosed is a method for forming the compositions, and articles prepared therefrom.