High Tg Copolycarbonate Blend for Heat Resistance and Clarity
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Solution Overview
Problem
High temperature polycarbonates are immiscible with other polymers, leading to degraded physical properties and processing difficulties, and existing compositions lack optimal heat stability and optical clarity.
Innovation Solution
A melt-blended composition of high Tg copolycarbonate and low Tg polycarbonate, combined with a transesterification catalyst, which renders the blend miscible and transparent, with improved molecular weight retention and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high temperature polycarbonate is used to improve heat resistance, then thermal stability is improved, but miscibility with other polymers deteriorates
Solution Approach 1:
The patent changes the chemical structure parameters of the polycarbonate by introducing specific aromatic dihydroxy compounds (formula 3) with at least 60% aromatic R6 groups, and controlling the mole ratio of x:y in formula (1) to be 35:65 to 90:10. This structural parameter change enables high Tg copolycarbonate to maintain miscibility with other polycarbonates while achieving Tg of 200°C or more, thus resolving the contradiction between heat resistance and miscibility.
Solution Approach 2:
The patent creates a composite polycarbonate system by combining high Tg copolycarbonate (formula 1) with low Tg polycarbonate (formula 9) in specific proportions (5 to 95 wt % high Tg copolycarbonate). This composite approach allows the material to exhibit both high thermal stability from the high Tg component and good miscibility from the low Tg component, resolving the contradiction between heat resistance and compositional stability.
2Temperature
If high temperature polycarbonate is used to improve heat resistance, then thermal stability is improved, but optical clarity deteriorates
Solution Approach 1:
The patent optimizes the chemical structure by using aromatic dihydroxy compounds with specific R6 groups (at least 60% aromatic) and controlling the mole ratio x:y to 35:65 to 90:10 in formula (1). These parameter changes result in a material that achieves Tg of 200°C or more while maintaining optical clarity, as demonstrated by the low haze value of less than 3% measured at 3.2 mm thickness.
Solution Approach 2:
The patent introduces specific local structural features (aromatic R6 groups in formula 3 and the specific mole ratio in formula 1) that locally enhance both thermal stability and optical clarity. The aromatic structure provides thermal stability while the specific molecular architecture maintains optical properties, resolving the contradiction between heat resistance and optical clarity.
3Temperature
If high temperature polycarbonate is used to improve heat resistance, then thermal stability is improved, but processing difficulty increases
Solution Approach 1:
The patent adjusts the glass transition temperature parameter to exactly 200°C or more while controlling the molecular structure (formula 1 with specific x:y ratio and formula 3 with aromatic R6 groups). This parameter optimization enables the material to process at manageable temperatures while maintaining high heat resistance, reducing processing difficulty.
Solution Approach 2:
The patent creates a composite system combining high Tg copolycarbonate (5 to 95 wt %) with low Tg polycarbonate (95 to 5 wt %). This composite structure allows the material to be processed more easily than pure high Tg polycarbonate while maintaining the desired heat resistance properties, thus resolving the contradiction between heat resistance and processing ease.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition achieves excellent physical properties, including low haze and high thermal stability, allowing for the production of optically clear thermoplastic polycarbonate with enhanced heat resistance and processing ease.
Implementation Method 1
a transesterification catalyst
Data Source
AI summary
Melt blended compositions, comprising up to 20 wt % of an optional additive, and 80-100 wt % of a copolycarbonate having a Tg of 200° C. or more of (1)wherein the mole ratio of x:y is 35:65 to 90:10, R1 is derived from a dihydroxy compound (2)wherein R3 and R5 are each independently a halogen or a C1-6 alkyl group, R4 is a C1-6 alkyl, phenyl, or phenyl substituted with up to five halogens or C1-6 alkyl groups, and each c is independently 0 to 4; R2 is derived from a dihydroxy compound (6):wherein Ra and Rb are each independently a halogen atom or a monovalent C1-6 alkyl group; p and q are each independently integers of 0 to 4; and Xa is a divalent group; and 95 to 5 wt % of a polycarbonate having a Tg of less than 200° C. of formula (9)wherein R9 derived from a dihydroxy compound of formula (6); and 0.001 to 0.1 wt % of a transesterification catalyst.