Silane-Modified Polybutadiene Rubber for Insert-Molded Polyester

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Insert-molded articles with metal inserts face cracking issues due to thermal expansion mismatch between resin and metal components, limiting their use in applications requiring high heat cycle resistance, especially in automotive and electronic parts with complex structures.

Innovation Solution

A thermoplastic polyester composition comprising 40-94% polyalkylene terephthalate, 5-50% reinforcing filler, and 1-30% semi-crystalline polyolefin block copolymer with vinyl aromatic or elastomeric polyolefin blocks, providing enhanced heat cycle resistance and mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal inserts are embedded in resin composition to combine properties of both materials, then mechanical strength and utility are improved, but cracking occurs during extreme temperature changes due to mismatched expansion coefficients

Engineering Contradiction:

Improvemechanical strengthVSAvoidheat cycle resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

A silane-modified polybutadiene rubber acts as an intermediary substance between the metal insert and resin composition. This intermediate layer has thermal expansion properties that bridge the gap between metal and resin, absorbing differential expansion stress and preventing crack formation at the interface during thermal cycling.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention creates a composite structure consisting of three components: metal insert, silane-modified polybutadiene rubber interlayer, and resin composition. This multi-phase composite material system combines the advantages of each component while mitigating their incompatibility, achieving both strength and thermal cycle resistance.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If resin composition is used in insert-molded articles with complicated structures and varying thickness, then adaptability to different applications is improved, but cracking susceptibility increases due to stress concentration in complex geometries

Engineering Contradiction:

Improveapplication versatilityVSAvoidheat cycle resistance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The silane-modified polybutadiene rubber serves as a stress-absorbing intermediary that is particularly effective in complex geometries. Its elastomeric properties allow it to accommodate stress concentrations in thin sections and complex shapes, preventing crack initiation and propagation in articles with varying thickness profiles.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If conventional impact modifiers are used to improve toughness, then impact resistance is improved, but heat cycle resistance remains insufficient due to inadequate bonding and stress distribution

Engineering Contradiction:

Improveimpact resistanceVSAvoidheat cycle resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention changes the chemical and physical parameters of the impact modifier by using silane-modified polybutadiene rubber instead of conventional elastomers. The silane modification enables chemical bonding to the resin matrix, while the polybutadiene provides elastomeric toughness. This parameter change achieves both impact resistance and heat cycle resistance simultaneously.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The silane-modified polybutadiene rubber creates a composite effect within the resin system, combining the toughness of polybutadiene with the bonding capability of silane groups. This internal composite structure improves both impact resistance and thermal cycle performance.

Inventive Principle:

Principle #40Composite materials

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 exhibits excellent heat cycle resistance with minimal cracking, achieving a heat cycle rating of less than or equal to 6 cracked holes after 385 cycles and maintaining tensile elongation greater than 3%, suitable for demanding automotive and electronic applications.

Implementation Method 1

the expansion and shrinkage coefficient (so-called liner expansion coefficient) can differ widely between the resin and metal portions of the insert-molded article

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

improved heat cycle resistance by silane-modified polybutadiene rubber

Methodology Applied

Scientific EffectStress absorption:

Data Source

PatentUS8853304B2Polyester compositions and insert-molded articles made therefrom

Publication Date: 2014.10.07 SABIC GLOBAL TECHNOLOGIES BV

AI summary

A thermoplastic polyester composition comprises polyalkylene terephthalate, a block copolymer comprising a semi-crystalline polyolefin block and at least one of a vinyl aromatic polymer block and an elastomeric polyolefin block, and reinforcing filler. The composition is capable of providing insert-molded articles, comprising a metal part, with high durability and resistance to cracking when subjected to a rigorous thermal cycle.