Polycarbonate Resin Composition Weld Line Strength

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Solution Overview

Problem

Polycarbonate resins exhibit high notch sensitivity and reduced impact strength due to low fluidity, which limits their applications, and existing solutions like impact modifiers and ABS graft copolymers either fail to improve fluidity or compromise mechanical strength and heat stability.

Innovation Solution

A polycarbonate resin composition comprising polycarbonate resin, rubber-modified-vinyl graft copolymer, and amorphous thermoplastic polyester copolymer, which enhances weld line strength, fluidity, and impact resistance without compromising heat resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If impact modifiers are added to polycarbonate resin, then impact resistance is improved, but fluidity remains low and residual stress persists

Engineering Contradiction:

Improveimpact resistanceVSAvoidfluidity

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent uses a composite material system consisting of polycarbonate resin, ABS graft copolymer, and SAN resin. This multi-component composite approach allows the impact modifier (ABS graft copolymer) to improve impact resistance while the SAN resin component addresses the fluidity issue, resolving the contradiction between strength improvement and manufacturing ease

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If ABS graft copolymer and SAN resin are mixed with polycarbonate resin to improve fluidity, then fluidity and reduced notch sensibility are achieved, but weld line strength is significantly reduced

Engineering Contradiction:

ImprovefluidityVSAvoidweld line strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent optimizes the compositional parameters by controlling the ratios of polycarbonate resin, ABS graft copolymer, and SAN resin within specific ranges. This parameter optimization ensures that the fluidity improvement from SAN resin does not excessively compromise weld line strength, balancing both requirements

Inventive Principle:

Principle #35Parameter changes

3Strength

If butadiene rubber amount is increased to improve weld strength, then weld strength is improved, but fluidity and heat stability are reduced

Engineering Contradiction:

Improveweld strengthVSAvoidfluidity

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent uses SAN resin as an intermediary component that mediates between the weld strength improvement from butadiene rubber and the fluidity requirement. The SAN resin helps maintain overall fluidity while allowing optimized weld strength through controlled butadiene rubber content

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8124683B2Polycarbonate resin composition with high weld line strength

Publication Date: 2012.02.28 LOTTE ADVANCED MATERIALS CO LTD

AI summary

A polycarbonate resin composition of the present invention comprises (A) about 30 to about 95 parts by weight of thermoplastic polycarbonate resin; (B) about 1 to about 50 parts by weight of rubber-modified-vinyl graft copolymer; (C) about 0 to about 50 parts by weight of vinyl copolymer; and (D) about 1 to about 50 parts by weight of amorphous thermoplastic polyester copolymer. The resin composition of the present invention can have excellent physical properties such as weld line strength, fluidity, impact resistance, and heat resistance.