Polycarbonate Compositions with Polyethercarbonate Polyols for Heat and Flow

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Solution Overview

Problem

Existing polycarbonate compositions used in injection molding for components like diffuser sheets in ultrabooks and automotive headlight covers face challenges with heat resistance, optical properties, flowability, and demolding issues, with Bisphenol A diphosphate improving flow but reducing heat resistance, and isosorbide esters causing volatile deposits.

Innovation Solution

Incorporating polyethercarbonate polyols into polycarbonate compositions to enhance heat resistance, optical properties, and flowability while maintaining demolding efficiency, achieved through a catalytic reaction of alkylene oxides and carbon dioxide with H-functional starter compounds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If Bisphenol A diphosphate is added to improve flowability, then melt viscosity decreases and flowability improves, but heat resistance (Vicat temperature) significantly decreases

Engineering Contradiction:

ImproveflowabilityVSAvoidheat resistance

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The patent uses polyethercarbonate polyol as an intermediary substance that mediates between the conflicting requirements of flowability and heat resistance. Unlike BDP which directly compromises heat resistance, the polyethercarbonate polyol acts as a buffer that improves flow while preserving the thermal properties of the polycarbonate matrix through its unique molecular structure containing both ether and carbonate groups

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the chemical parameter of the additive from BDP (a phosphate ester) to polyethercarbonate polyol (a polyol with specific molecular weight and functionality). This parameter change in the additive's chemical structure allows achieving the same flow improvement effect without the harmful side effect of reduced heat resistance, as the polyol integrates more compatibly with the polycarbonate matrix

Inventive Principle:

Principle #35Parameter changes

2Productivity

If isosorbide esters are added to improve flowability, then flow properties improve, but volatility increases causing deposit formation during injection molding

Engineering Contradiction:

Improveflow propertiesVSAvoiddeposit formation

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces isosorbide esters with polyethercarbonate polyol, which has lower volatility and does not form deposits. The polyol acts as a more stable, non-volatile alternative that achieves the same flow improvement without generating harmful deposits during the injection molding process

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent converts the potential harm of volatile additive decomposition into a benefit by selecting polyethercarbonate polyol with high thermal stability. The polyol's stable molecular structure prevents decomposition and deposit formation, turning the challenge of additive stability into an advantage for process reliability

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Illumination intensity

If polyethercarbonate polyol is added to improve optical properties and flowability, then transmission increases and yellowness index decreases, but melt viscosity may increase at high concentrations

Engineering Contradiction:

Improveoptical transmissionVSAvoidmelt viscosity

Core Design Contradiction:

Illumination intensityVSProductivity

Solution Approach 1:

The patent applies partial action by limiting the polyethercarbonate polyol content to optimal ranges (0.01-5 wt%, preferably 0.1-2 wt%). This partial addition is sufficient to achieve the desired optical property improvements and flowability enhancement without excessive concentration that would cause melt viscosity to increase and counteract the benefits

Inventive Principle:

Principle #16Partial or excessive action

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 compositions exhibit improved optical transmission, reduced yellowness, and enhanced melt stability with higher melt volume flow rates, maintaining heat resistance and facilitating better demolding and processing.

Implementation Method 1

Polyethercarbonate polyols are typically produced by catalytic reaction of alkylene oxides (epoxides) and carbon dioxide in the presence of H-functional starter compounds

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 2

This reaction is schematically depicted in Scheme (I), where R represents an organic radical such as alkyl, alkylaryl, or aryl, each of which may also contain heteroatoms such as O, S, Si, etc.

Methodology Applied

Scientific EffectCopolymerization:

Implementation Method 3

At the same time, the coefficients of sliding and static friction are reduced, resulting in improved demolding and processing behavior in injection molding

Methodology Applied

Scientific EffectFriction reduction: Friction

Implementation Method 4

polycarbonate compositions exhibit improved optical properties—i.e., higher transmission in the VIS range and a lower yellowness index

Methodology Applied

Scientific EffectOptical transmission:

Data Source

PatentEP4157940B1Polycarbonate compounds containing polyether carbonate polyols

Publication Date: 2025.07.23 COVESTRO DEUTSCHLAND AG

AI summary

The invention relates to polyether carbonate polyol-containing polycarbonate-based compositions. Said compositions exhibit increased transmission in the VIS range due to the additive and further advantageous properties, such as improved demoulding behaviour. Even small amounts have a significant influence.