Solventless Polyurethane Adhesive Composition for Acid-Resistant Bonding

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Solution Overview

Problem

Two-component solventless polyurethane-based laminating adhesives exhibit high initial viscosity, weak initial bonds, slow bond development, and poor chemical resistance, especially in acidic conditions, with silane adhesion promoters deteriorating bond strength under acid treatment and requiring dry storage.

Innovation Solution

A solventless polyurethane adhesive composition comprising an isocyanate component with a prepolymer derived from specific isocyanate and isocyanate-reactive compounds, including alkylene oxide side chains, and an isocyanate-reactive component with distinct reactive compounds, applied separately and mixed before use, forming a polyurethane adhesive layer with improved properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two-component solventless polyurethane-based laminating adhesives are used, then chemical resistance is improved, but bond strength deteriorates under acid treatment

Engineering Contradiction:

Improvechemical resistanceVSAvoidbond strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent changes the chemical composition parameters by introducing specific carboxylic acid groups and adjusting the NCO/OH ratio to achieve both acid resistance and bond strength simultaneously

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite adhesive system combining polyurethane base with carboxylic acid functional groups and optional silane adhesion promoters, achieving synergistic effects for both chemical resistance and bond strength

Inventive Principle:

Principle #40Composite materials

2Strength

If silane adhesion promoter is incorporated to improve bond strength, then bond strength is improved, but acid resistance deteriorates

Engineering Contradiction:

Improvebond strengthVSAvoidacid resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent carefully controls the amount of silane adhesion promoter at 0.1-5 wt% and balances it with carboxylic acid functional groups to achieve both bond strength and acid resistance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies silane adhesion promoter locally at controlled concentrations rather than uniformly throughout the adhesive, allowing bond strength enhancement without compromising overall acid resistance

Inventive Principle:

Principle #3Local quality

3Reliability

If two-component solventless polyurethane-based laminating adhesive is used, then chemical resistance is improved, but initial viscosity increases

Engineering Contradiction:

Improvechemical resistanceVSAvoidinitial viscosity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent adjusts molecular weight parameters and compositional ratios of the polyol components to reduce initial viscosity while preserving chemical resistance properties

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent divides the adhesive into two separate components (isocyanate component and polyol component) that are mixed immediately before application, allowing each component to be optimized independently for lower viscosity

Inventive Principle:

Principle #1Segmentation

4Reliability

If two-component solventless polyurethane-based laminating adhesive is used, then chemical resistance is improved, but bond development speed decreases

Engineering Contradiction:

Improvechemical resistanceVSAvoidbond development speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent performs preliminary formulation of the two components separately with pre-calculated NCO/OH ratios, enabling rapid mixing and immediate bond development without prolonged reaction times

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent optimizes the NCO/OH ratio and molecular weight parameters to accelerate the curing reaction speed while maintaining chemical resistance

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 composition achieves reduced viscosity, enhanced bond strength, improved chemical resistance, and heat seal strength, maintaining performance in acidic conditions without the need for dry storage.

Implementation Method 1

The adhesive composition comprises an isocyanate component and an isocyanate-reactive component. The isocyanate component includes a prepolymer with free isocyanate groups. When mixed, these components react to form polyurethane bonds.

Methodology Applied

Scientific EffectPolyaddition reaction: Chemical Bonding

Implementation Method 2

The prepolymer comprises side chains with the structure -R2-(O-R1-O)n-R3, where R1 is C2-C4 alkylene, R2 is C1-C6 alkylene, R3 is C1-C6 alkyl, and n is 8-25. These side chains provide improved chemical resistance, especially in acidic conditions.

Methodology Applied

Scientific EffectChemical resistance: Cohesion

Data Source

PatentEP3947588B1Solventless adhesive composition and method for preparing thereof

Publication Date: 2025.06.25 ARKEMA FRANCE SA

AI summary

A solventless adhesive composition is provided. The solventless adhesive composition comprises (A) an isocyanate prepolymer having a side chains represented by -R2-(0-R1-0)n-R3 and (B) an isocyanate-reactive component, and exhibits improved bond strength, heat seal strength, adhesive COF property and optical appearance. A laminate product prepared with said solventless adhesive composition as well the method for preparing the laminate product are also provided.