Polyurethane Adhesive Bonding Crosslinked Rubber

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Solution Overview

Problem

Polyurethane adhesives experience significant weakening at higher temperatures, particularly above 100°C, and struggle to maintain high peel strength on vulcanized elastomers, necessitating the development of improved formulations for applications under high loads and elevated temperatures.

Innovation Solution

A two-component polyurethane adhesive system comprising Part A with a first polyol, primary diamine, and secondary diamine, and Part B as a prepolymer reaction product of polyisocyanate and polyol, with specific weight ratios and diamine content levels, enhancing peel strength at temperatures up to 82°C or higher.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If chain extenders are added to polyurethane adhesives to increase Tg and provide high-Tg hard segment, then strength (tear strength and elastomeric modulus) is improved, but peel strength at higher temperatures (82°C or higher) is not sufficiently improved

Engineering Contradiction:

Improvetear strength and elastomeric modulusVSAvoidpeel strength at higher temperatures

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the polyurethane adhesive by incorporating specific ratios of primary diamine (7-19 wt% of Part A) and secondary diamine (15-23 wt% of Part A), along with specific polyol combinations. This parameter optimization enables the adhesive to achieve both high strength at room temperature and maintained peel strength at elevated temperatures up to 82°C or higher, resolving the contradiction between strength improvement and high-temperature reliability.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If polyurethane adhesives are used to bond crosslinked elastomers, then good adhesion is achieved, but considerable weakening occurs at temperatures exceeding 100°C

Engineering Contradiction:

Improveadhesion to crosslinked elastomersVSAvoidbond strength at temperatures exceeding 100°C

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent creates a composite adhesive system combining multiple components: specific polyols (including polyester polyols with 2-7 functionality and 50-8000 g/mol equivalent weight), primary diamines, secondary diamines, and polyisocyanate prepolymer. This composite formulation provides both good adhesion to crosslinked elastomers and resistance to weakening at temperatures exceeding 100°C, as demonstrated by maintained peel strength at 82°C or higher.

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 described adhesive system significantly improves peel strength on cross-linked elastomeric materials, demonstrating enhanced performance at elevated temperatures compared to conventional systems.

Implementation Method 1

Part B comprises a prepolymer that is a reaction product of at least one polyisocyanate and at least a second polyol

Methodology Applied

Scientific EffectPolyaddition: Chemical Bonding

Implementation Method 2

Part A comprises (i) at least a first polyol, (ii) a primary diamine, and (iii) a secondary diamine

Methodology Applied

Scientific EffectPolyurethane formation: Chemical Bonding

Data Source

PatentUS12195646B2Polyurethane adhesive for bonding crosslinked rubber

Publication Date: 2025.01.14 DDP SPECIALTY ELECTRONICS MATERIALS US LLC

AI summary

Disclosed herein are two-component polyurethane adhesive systems comprising a mixture of primary and secondary diamines.