Curable Resin Composition for Metal Adhesion

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Solution Overview

Problem

Existing adhesive compositions used in hybrid components, when exposed to hot water, experience decreased adhesion and can form voids at the interface between metal and adhesive layers, leading to reduced corrosion resistance and durability over time.

Innovation Solution

A curable resin composition combining a polyamide-based resin with a melting point of 170°C or higher and a polyamide-based resin with a melting point of 150°C or lower, along with a blocked polyisocyanate and an epoxy compound, to form a durable and heat-resistant adhesive layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a copolyamide-based hotmelt adhesive containing blocked isocyanate and epoxide is used to bond metal to polymer, then high adhesion and durability can be achieved, but voids form at the interface when thermoplastic resin is molded on the adhesive layer

Engineering Contradiction:
Improveadhesion strengthVSAvoidinterface quality
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent modifies the chemical composition parameters of the adhesive by incorporating specific ratios of blocked isocyanate (1-10 wt%) and epoxide (1-10 wt%) into the copolyamide matrix. This compositional parameter change enables the adhesive to maintain strong bonding while preventing void formation during subsequent thermoplastic resin molding processes.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the adhesive layer is heated to high temperatures for molding, then the thermoplastic resin can be bonded, but the adhesion of the adhesive decreases when exposed to hot water

Engineering Contradiction:
Improvemolding efficiencyVSAvoidcorrosion resistance
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent creates a composite adhesive system by combining copolyamide base resin with blocked isocyanate and epoxide compounds. This composite material structure provides both high-temperature processing capability and resistance to hot water corrosion, resolving the contradiction between molding efficiency and long-term reliability.

Inventive Principle:
Principle #40Composite materials

3Device complexity

If a single polyamide-based resin is used in the adhesive composition, then the formulation is simple, but the adhesion and heat resistance are insufficient at molding temperatures of 260°C or lower

Engineering Contradiction:
Improveformulation complexityVSAvoidheat resistance
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent applies local quality by differentiating the functional roles of different polyamide-based resins within the adhesive composition. By selecting resins with specific melting points and chemical properties, each component contributes specialized functions (adhesion, heat resistance, processability) to achieve overall performance at molding temperatures of 260°C or lower.

Inventive Principle:
Principle #3Local quality

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 provides high adhesion and heat resistance, preventing void formation and maintaining durability even when molded at temperatures up to 280°C, ensuring a strong bond between the metal substrate and the thermoplastic resin.

Implementation Method 1

a curable resin composition containing a polyamide-based resin (A) having an amino group, a blocked polyisocyanate (B), and an epoxy compound (C)

Methodology Applied
Scientific EffectChemical Bonding: Chemical Bonding

Implementation Method 2

a curable resin composition containing a polyamide-based resin (A) having an amino group, a blocked polyisocyanate (B), and an epoxy compound (C)

Methodology Applied
Scientific EffectChemical Bonding: Chemical Bonding

Implementation Method 3

a polyamide-based resin (A1) having a melting point of 170° C. or higher and a polyamide-based resin (A2) having a melting point of 150° C. or lower

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentUS12071572B2Curable resin composition, use thereof, and production method thereof
Publication Date: 2024.08.27 DAICEL EVONIK LTD

AI summary

[Object]The present invention provides a curable resin composition useful for imparting high durability and adhesion to a substrate such as a metal.[Solution]A curable resin composition is prepared by combining a polyamide-based resin (A) having an amino group, a blocked polyisocyanate (B), and an epoxy compound (C). The polyamide-based resin (A) contains a polyamide-based resin (A1) having a melting point of 170° C. or higher and a polyamide-based resin (A2) having a melting point of 150° C. or lower. The mass ratio of the polyamide-based resin (A1) and the polyamide-based resin (A2) is, in the form of the former/the latter, from 65/35 to 35/65.