Resin Bonding with Solvent Swelling and Low-Temperature Pressing

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Solution Overview

Problem

Conventional methods of joining resin members risk deformation, external appearance defects, and solvent residue in the joined portion.

Innovation Solution

A method involving a solvent with a boiling point equal to or lower than the glass transition temperature of the thermoplastic resin, allowing a specific degree of swelling, is used to form a coating layer, followed by lamination and heating at a temperature below the glass transition temperature to prevent solvent residue and defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional joining methods using organic solvents are used, then resin members can be joined together, but solvent residue remains in the joined portion and deformation or external appearance defects occur

Engineering Contradiction:
Improvejoining qualityVSAvoidsolvent residue and deformation
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by carefully selecting solvents with specific boiling points relative to the resin's glass transition temperature, and by controlling the heating temperature during pressing to be at or below the glass transition temperature. This resolves the contradiction by changing the thermal parameters of the joining process to prevent both solvent residue and resin deformation, achieving reliable joining without harmful effects.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces conventional high-temperature thermal joining methods with a controlled low-temperature pressing method. By substituting the traditional heating-based joining mechanism with a controlled pressing process at temperatures at or below the glass transition temperature, the method eliminates solvent residue and prevents deformation while maintaining joining effectiveness.

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

2Strength

If heating temperature is increased to improve joining strength, then resin members join more strongly, but deformation and external appearance defects increase

Engineering Contradiction:
Improvejoining strengthVSAvoidresin member deformation
Core Design Contradiction:
StrengthVSShape

Solution Approach 1:

The patent changes the temperature parameter from conventional high-temperature joining to low-temperature pressing at or below the glass transition temperature. This parameter change enables achieving sufficient joining strength through controlled pressing without causing resin deformation or external appearance defects, resolving the contradiction between strength and shape preservation.

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

Prevents solvent residue and deformation while ensuring high-quality joining of resin members.

Implementation Method 1

the solvent allowing the thermoplastic resin to have a degree of swelling of 1.05 or more and 3.00 or less when the thermoplastic resin is swollen by the solvent

Methodology Applied
Scientific EffectSwelling:

Implementation Method 2

pressing the laminate in the lamination direction while heating at a heating temperature H °C that is equal to or lower than R °C where R °C is the glass transition temperature of the thermoplastic resin

Methodology Applied
Scientific EffectGlass transition temperature control:

Data Source

PatentEP4299291B1Method for bonding resin members
Publication Date: 2026.01.14 ZEON CORP
  • EP4299291B1 patent drawingFigure 1A~1B
  • EP4299291B1 patent drawing

AI summary

Disclosed is a method of joining resin members that includes: forming a coating layer by applying a solvent to a surface of a resin member, the solvent allowing the thermoplastic resin to have a degree of swelling of 1.05 or more and 3.00 or less when the thermoplastic resin is swollen by the solvent, and having a boiling point B °C of R °C or lower where R °C is a glass transition temperature of the thermoplastic resin; laminating resin members one another via the coating layer to form a laminate; and pressing the laminate in the lamination direction while heating at a heating temperature H °C that is equal to or lower than R °C.