Thiol-Acrylate Foam Precursor Curing Without Isocyanates

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Solution Overview

Problem

Existing sprayable foam formulations, such as polyurethane foams, are affected by ambient moisture for curing, leading to variable crosslinking rates and are toxic due to the use of isocyanates, which are also flammable and explosive.

Innovation Solution

A foam precursor composition comprising a di- or tri-functional (meth)acrylate oligomer, a di- or higher-functional thiol compound, and a borane initiator, which undergoes thiol-X chemistry for curing, independent of moisture and without isocyanates, allowing for stable foam formation in aerosol cans.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polyurethane foam formulations use isocyanates for curing, then foam formation and crosslinking are achieved, but toxicity and flammability increase

Engineering Contradiction:

Improvefoam formation reliabilityVSAvoidtoxicity and flammability

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the chemical parameters of the foam formulation by replacing isocyanate-based polyurethane chemistry with silane-modified polyether chemistry. This substitution fundamentally alters the chemical composition to eliminate toxic isocyanates while maintaining foam formation capability through silane crosslinking reactions that occur upon contact with moisture or catalysts.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention employs readily available silane-modified polyether precursors that can be stored in aerosol cans and activated on-demand. These materials are designed to remain stable during storage but react quickly when exposed to atmospheric moisture or catalysts, providing a safe, on-demand foam generation system without requiring long-term stability of reactive components.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If polyurethane foam formulations rely on ambient moisture for curing, then crosslinking occurs, but crosslinking rate becomes variable and unreliable

Engineering Contradiction:

Improvecuring consistencyVSAvoidcuring speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The invention incorporates catalyst systems that respond to environmental conditions while maintaining controlled reaction rates. The silane crosslinking mechanism provides feedback through consistent reaction kinetics that are less sensitive to ambient humidity variations compared to traditional isocyanate-moisture curing, enabling more predictable and reliable foam formation across different environmental conditions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The invention modifies the chemical parameters of the curing mechanism by using silane hydrolysis and condensation reactions instead of isocyanate-moisture reactions. This change in chemical pathway provides more consistent reaction kinetics and crosslinking rates that are less dependent on ambient moisture levels, improving curing reliability and predictability.

Inventive Principle:

Principle #35Parameter changes

3Strength

If isocyanates are used in foam formulations, then foam crosslinking is achieved, but safety hazards from inhalation, ingestion, and skin contact increase

Engineering Contradiction:

Improvefoam crosslinkingVSAvoidhealth hazards

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The invention extracts and removes isocyanate components from the foam formulation entirely, replacing them with silane-modified polyether precursors. This extraction eliminates the source of health hazards associated with isocyanate inhalation, ingestion, and skin contact while preserving the essential foam crosslinking function through alternative silane-based chemistry.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention uses safe, non-toxic silane-modified polyether materials that can be handled without special protective measures during storage and application. These materials only become reactive when intentionally activated by moisture or catalysts, providing a safe alternative to hazardous isocyanates while achieving the desired foam crosslinking strength.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 rapid curing within 1-3 hours, regardless of humidity and temperature, without the use of isocyanates, ensuring consistent foam formation and safety from toxic compounds.

Implementation Method 1

Methodology Applied

Scientific EffectThiol-X chemistry: Chemical Bonding

Implementation Method 2

a borane initiator, which undergoes thiol-X chemistry for curing

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentUS10875942B2Thiol-acrylate based foam precursor composition

Publication Date: 2020.12.29 GREENSEAL CHEM NV

AI summary

A polymeric foam precursor composition including the following components:(a) a di- or tri-functional (meth)acrylate oligomer (2);(b) a di- or higher-functional thiol compound (3); and(c) a borane compound (4) as initiator.The foam precursor composition can be isocyanate free, and the curing rate is largely moisture independent and can cure at low temperatures, below freezing point.