Single-Tg Thermoplastic Resin Foam for Heated Shape Stability

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Solution Overview

Problem

Existing thermoplastic resin foams and fiber-reinforced composites suffer from low heat resistance, leading to softening and reduced rigidity when heated, which is a limitation in applications requiring heat-dimensional stability.

Innovation Solution

A combination of crystalline and amorphous polyester resins, along with a polyimide resin, is used to create a thermoplastic resin foam and fiber-reinforced composite, achieving a single glass transition temperature and enhanced heat resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a thermoplastic resin foam is used for food containers requiring microwave heating, then light weight and high heat insulation are achieved, but heat resistance deteriorates causing softening and deformation

Engineering Contradiction:
ImproveweightVSAvoidheat resistance
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The patent uses a composite thermoplastic resin composition comprising multiple polyester resins (including crystalline and amorphous types) and polyimide resin. This composite material approach allows the foam to achieve both light weight and improved heat resistance by combining the advantages of different polymer materials, resolving the contradiction between weight and heat resistance.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the glass transition temperature parameter by selecting specific polyester resins with appropriate Tg values and combining them with polyimide resin. This parameter change enables the foam to maintain rigidity at microwave heating temperatures while preserving the lightweight characteristic, thus resolving the heat resistance issue without sacrificing weight advantage.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If a heat set step is added to promote crystallization and improve heat-dimensional stability, then heat resistance is improved, but molding time increases

Engineering Contradiction:
Improveheat-dimensional stabilityVSAvoidmolding time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent incorporates crystalline polyester resin and amorphous polyester resin with specific Tg values into the foam formulation in advance. This preliminary action of selecting appropriate resin combinations eliminates the need for subsequent heat set steps, achieving heat-dimensional stability directly during the molding process and reducing molding time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the resin composition parameters by using specific polyester resins with controlled crystallinity and Tg values. This parameter modification allows the foam to achieve heat-dimensional stability without requiring additional heat set processing, thus reducing molding time while maintaining reliability.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If a heat set step at high temperature is implemented to improve heat resistance, then heat-dimensional stability is improved, but equipment investment increases

Engineering Contradiction:
Improveheat resistanceVSAvoidequipment requirement
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs a composite resin system comprising crystalline polyester, amorphous polyester with specific Tg, and polyimide. This composite material approach achieves high heat resistance through material composition rather than high-temperature processing equipment, eliminating the need for expensive heat set equipment while maintaining reliability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the material parameters by selecting polyester resins with appropriate Tg values and combining them with polyimide. This parameter change enables the foam to achieve heat resistance at lower processing temperatures, avoiding the need for high-temperature equipment investment while maintaining heat-dimensional stability.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If the glass transition temperature is increased to improve heat resistance, then heat-dimensional stability is improved, but ease of processing deteriorates

Engineering Contradiction:
Improveheat resistanceVSAvoidprocessing ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent uses a composite system with crystalline polyester, amorphous polyester having specific Tg, and polyimide resin. This composite approach balances heat resistance and processability by combining materials with different thermal properties, allowing the foam to maintain both high heat resistance and ease of processing during molding operations.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent optimizes the Tg parameter by selecting specific polyester resins with appropriate glass transition temperatures and combining them with polyimide. This parameter optimization ensures the foam has sufficient heat resistance while maintaining good processability during molding, resolving the contradiction between heat resistance and ease of operation.

Inventive Principle:
Principle #35Parameter changes

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 resulting materials exhibit improved heat resistance and heat-dimensional stability, maintaining rigidity and handling properties even when heated.

Implementation Method 1

the thermoplastic resin includes a polyester resin and a polyimide resin, and the thermoplastic resin foam shows a single glass transition temperature Tg

Methodology Applied
Scientific EffectGlass transition temperature:

Data Source

PatentEP4190533B1Thermoplastic resin foam, thermoplastic resin foam sheet, fiber-reinforced resin composite, method for manufacturing thermoplastic resin foam, thermoplastic resin foam molded article, method for manufacturing thermoplastic resin foam molded article, and foamed resin composite
Publication Date: 2025.10.01 SEKISUI PLASTICS CO LTD
  • EP4190533B1 patent drawingFigure 1
  • EP4190533B1 patent drawingFigure 2
  • EP4190533B1 patent drawingFigure 3

AI summary

A thermoplastic resin foam including a thermoplastic resin, wherein: the thermoplastic resin includes a polyester resin and a polyimide resin, and the thermoplastic resin foam shows a single glass transition temperature Tg. The glass transition temperature of the thermoplastic resin is preferably 80 to 130 °C. An absolute value of difference between heat absorption and heat generation, each determined by heat flux differential scanning calorimetry at a heating rate of 10 °C/min, is preferably 3 to 35 J/g.