Fiber-Reinforced Resin Substrate for Joining Dissimilar Thermoplastics

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Solution Overview

Problem

Existing fiber-reinforced composite materials with thermoplastic resins struggle with insufficient joining strength when integrating members made of different thermoplastic resins, leading to prolonged production times and reduced material strength due to mechanical or adhesive methods, and limited design freedom in thermal welding.

Innovation Solution

A fiber-reinforced resin substrate is created by impregnating two different thermoplastic resins into continuous reinforcing fibers, forming a boundary region with one resin exposed on each surface, and ensuring some fibers cross this boundary, using crystalline resins with high melting points and controlled surface free energy for enhanced adhesion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If mechanical joining methods (bolts, rivets, screws) are used to integrate fiber-reinforced composite members, then the members can be joined together, but the production step is prolonged and production cost increases due to additional processing steps like creating holes

Engineering Contradiction:
Improveproduction process simplicityVSAvoidproduction time
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent merges the joining function with the resin matrix material itself. By incorporating thermoplastic resin particles or powder into the fiber-reinforced composite, the resin serves dual purposes: as the matrix material and as the joining agent. This eliminates the need for separate mechanical joining operations like drilling holes and installing fasteners, thereby simplifying the manufacturing process and reducing production time.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The thermoplastic resin particles act as an intermediary between the fiber-reinforced composite members. During the molding process, these resin particles melt and flow into the interface between members, creating a bonding layer that joins the members together. This intermediary resin material enables joining without requiring direct mechanical intervention, thus improving productivity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If adhesive joining methods are used to integrate fiber-reinforced composite members, then the members can be joined together, but the production process is prolonged due to bonding preparation, coating, and curing steps

Engineering Contradiction:
Improvejoining method simplicityVSAvoidbonding and curing time
Core Design Contradiction:
Ease of manufactureVSLoss of time

Solution Approach 1:

The patent replaces the chemical adhesive bonding system with a thermal fusion system. Instead of using liquid adhesives that require coating, curing, and extended bonding time, the invention uses thermoplastic resin particles that are already embedded in the composite structure. These particles are activated by heat during the molding process, melting and fusing the members together in a single step, thereby eliminating the multi-step adhesive bonding process and significantly reducing time loss.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If thermal welding methods are used to join members made of different thermoplastic resins, then joining time may be shortened, but the degree of freedom in design is limited due to compatibility requirements

Engineering Contradiction:
Improvejoining speedVSAvoiddesign freedom
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent applies local quality by incorporating thermoplastic resin particles specifically at the joining interfaces between members made of different thermoplastic resins. These resin particles are localized at the boundary regions where joining is needed, rather than uniformly distributed throughout the entire composite. This localized application allows for targeted joining of dissimilar materials while maintaining the integrity and properties of the base materials, thereby enabling design freedom with different resin combinations.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention creates a composite structure within the composite material itself by embedding thermoplastic resin particles into the fiber-reinforced matrix. This multi-phase composite approach (fibers + matrix resin + thermoplastic particles) enables the system to accommodate different thermoplastic resin types at different locations. The thermoplastic particles act as a compatible bonding phase that can join dissimilar thermoplastic members, expanding design freedom while maintaining efficient thermal welding speeds.

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

This approach enables strong, durable integration of members with different thermoplastic resins, improving joining strength and reducing production time while maintaining design flexibility.

Implementation Method 1

a fiber-reinforced resin substrate obtained by impregnating a thermoplastic resin (A) and a thermoplastic resin (B) into continuous reinforcing fibers

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

both the thermoplastic resin (A) and the thermoplastic resin (B) are a crystalline resin having a melting point of 200°C or higher

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentEP4249541B1Fiber-reinforced resin substrate, preform, integrated molded article, and method for producing fiber-reinforced resin substrate
Publication Date: 2026.01.28 TORAY INDUSTRIES INC
  • EP4249541B1 patent drawingFigure 1(a)~2
  • EP4249541B1 patent drawingFigure 3(a)~4
  • EP4249541B1 patent drawingFigure 5(a)~5(c)

AI summary

The purpose of the present invention is to provide a fiber-reinforced resin substrate in which a plurality of resins having differing properties are strongly composited. The present invention is a fiber-reinforced resin substrate obtained by impregnating a thermoplastic resin (A) and a thermoplastic resin (B) into continuous reinforcement fibers, wherein: a thermoplastic resin (A) layer, which comprises the thermoplastic resin (A) and is exposed at one surface, and a thermoplastic resin (B) layer, which comprises the thermoplastic resin (B) and is exposed at the other surface, form a boundary region; at least some of the continuous reinforcement fibers exist in a manner spanning across the boundary region; and both the thermoplastic resin (A) and the thermoplastic resin (B) are a crystalline resin having a melting point of not less than 200°C.