Free Radical Initiators for Isocyanate Trimerization Control

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Solution Overview

Problem

Conventional trimerization catalysts in polyurethane reaction systems cause rapid and uncontrollable isocyanate trimerization reactions due to high catalytic activity, leading to excessive heat retention and temperature increases, making it difficult to achieve a controlled reaction process.

Innovation Solution

The use of free radical initiators, such as peroxides and azo compounds, to catalyze the trimerization of isocyanates, allowing for a slow and controllable polymerization process with sufficient time for heat dissipation, maintaining a constant reaction temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional trimerization catalysts (phosphorus-containing substances, amines, or metal salts) are used to catalyze isocyanate trimerization, then the trimerization reaction proceeds rapidly and achieves high crosslinking density, but the reaction becomes uncontrollable with rapid temperature increase and excessive heat retention

Engineering Contradiction:

Improvetrimerization reaction rateVSAvoidreaction process controllability

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The invention changes the fundamental parameter of catalysis mechanism by replacing conventional trimerization catalysts (phosphorus-containing substances, amines, metal salts) with free radical initiators. This parameter change transforms the reaction pathway from ionic/trimerization catalysis to free radical polymerization, enabling controllable reaction rates while maintaining high crosslinking density through the gradual consumption of isocyanate groups.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention introduces free radical initiators as intermediary substances that mediate the trimerization reaction. These initiators (peroxides, azo compounds) generate free radicals that progressively catalyze the reaction, acting as a buffer between the reactive isocyanate groups and the final crosslinked structure, thereby enabling controlled heat release and temperature management.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of time

If conventional trimerization catalysts are used, then the reaction completes in tens of seconds to minutes, but the released heat cannot be effectively dissipated, causing temperature to rise markedly and further accelerating the reaction in a self-accelerating cycle

Engineering Contradiction:

Improvereaction timeVSAvoidreaction system temperature

Core Design Contradiction:

Loss of timeVSTemperature

Solution Approach 1:

The invention implements periodic action through the staged decomposition of free radical initiators. Instead of instantaneous catalyst action, the initiators decompose progressively over time, releasing free radicals in a controlled sequence. This periodic generation of active species allows heat to be dissipated between reaction bursts, preventing thermal runaway while maintaining overall reaction efficiency.

Inventive Principle:

Principle #19Periodic action

3Strength

If high catalytic activity is used to achieve fast trimerization, then crosslinking density is enhanced, but the reaction becomes violent and difficult to control

Engineering Contradiction:

Improvecrosslinking densityVSAvoidreaction violence

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The invention substitutes the mechanical/ionic catalysis mechanism with a chemical free radical mechanism. Instead of using catalysts that directly activate isocyanate groups through ionic interactions (which cause violent reactions), free radical initiators create a gentler chemical pathway that progressively builds crosslinks through radical-mediated polymerization, reducing reaction violence while maintaining crosslinking effectiveness.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This approach results in a mild and controllable trimerization process, preventing temperature increases and enhancing the controllability of the resin system, while producing (poly)isocyanurate with improved properties for applications like heat-insulation materials.

Implementation Method 1

The use of free radical initiators, such as peroxides and azo compounds, to catalyze the trimerization of isocyanates

Methodology Applied

Scientific EffectFree radical initiation:

Implementation Method 2

The trimerization reaction is usually carried out by the polymerization of three isocyanate groups into one isocyanurate six-membered ring

Methodology Applied

Scientific EffectTrimerization reaction:

Implementation Method 3

allowing for a slow and controllable polymerization process with sufficient time for heat dissipation, maintaining a constant reaction temperature

Methodology Applied

Scientific EffectHeat dissipation:

Data Source

PatentEP3747924A1Rigid polyurethane foam

Publication Date: 2020.12.09 COVESTRO DEUTSCHLAND AG

Figure 1

AI summary

The present invention relates to a process for preparing a (poly)isocyanurate, a (poly)isocyanurate prepared with said process and use thereof. The process according to the present invention in which a free radical initiator is used as a trimerization catalyst provides a trimerization catalytic reaction system in which the reaction rate is mild and controllable, and the trimerization reaction of an isocyanate can be carried out in a very moderate manner.