Thioether Endcapped Polycarbonate Color Stability

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Solution Overview

Problem

Polycarbonates used in automotive and electronics industries face challenges with increased color during molding and poor color stability, especially at high temperatures, and require improved mold release properties to prevent plate-out of mold release agents.

Innovation Solution

Incorporating thioether carbonyl endcaps with specific sulfur-containing structures into polycarbonates to enhance color stability and mold release properties, allowing for reduced use of mold release agents and maintaining performance at high temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If higher levels of mold release agents are used to improve mold release, then ease of operation is improved, but plate out of the release agent in the molds occurs, worsening manufacturing precision and surface finish

Engineering Contradiction:

Improvemold releaseVSAvoidplate out

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameters of the polycarbonate by incorporating sulfur-containing end cap groups (specifically thioether and sulfone end caps at controlled concentrations). This compositional parameter change fundamentally alters the polymer's interaction with mold release agents, enabling effective mold release at lower release agent levels and preventing plate-out accumulation on mold surfaces.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite polycarbonate structure by combining standard polycarbonate chains with sulfur-containing end cap groups. This composite approach integrates the beneficial properties of sulfur compounds (improved mold release, reduced plate-out) while maintaining the core polycarbonate's structural integrity and mechanical properties.

Inventive Principle:

Principle #40Composite materials

2Productivity

If polycarbonates are subjected to high temperature molding, then productivity is improved, but color stability deteriorates and yellowness increases

Engineering Contradiction:

Improvemolding speedVSAvoidcolor stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent modifies the chemical composition by incorporating sulfur-containing end cap groups (thioether and sulfone structures) that act as thermal stabilizers. These compositional changes raise the degradation temperature and improve color stability, allowing the polycarbonate to withstand high-temperature molding processes (above 200°C) without significant yellowness development or color degradation.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If conventional polycarbonates are used, then ease of manufacture is maintained, but color and color stability with heat aging are insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidcolor stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by incorporating sulfur-containing end cap groups during the polycarbonate synthesis stage itself, rather than adding stabilizers as separate post-processing steps. The end cap groups are integrated into the polymer chains during manufacturing, providing built-in thermal and color stability that activates during subsequent heat aging and molding processes.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP3660075B1Endcapped polycarbonates, methods of manufacture, and articles formed therefrom

Publication Date: 2022.06.08 SHPP GLOBAL TECH BV

Figure 1~2

AI summary

An endcapped polycarbonate, comprising thioether carbonyl endcaps of the formula wherein L is a C1-12 aliphatic or aromatic linking group, and R is a C1-20 alkyl, C6-18 aryl, or C7-24 arylalkylene.