Polyisocyanate Flocculation Stability via Substoichiometric Additives

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Solution Overview

Problem

Existing methods for stabilizing polyisocyanates in solvents against flocculation require high stoichiometric amounts of water scavengers, which reduce NCO values and lead to side effects such as reduced coatings properties and increased reactivity, making them uneconomic and inefficient.

Innovation Solution

The use of phosphorus-containing acidic compounds and open-chain trisubstituted amines as additives in substoichiometric amounts to reduce flocculation and precipitation in polyisocyanate mixtures, providing improved stability without the need for high concentrations of water scavengers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high stoichiometric amounts of water scavengers are used to stabilize polyisocyanates against flocculation, then storage stability is improved, but NCO values are reduced and coatings properties deteriorate

Engineering Contradiction:

Improvestorage stabilityVSAvoidNCO value

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The invention changes the chemical parameters by using phosphorus-containing acidic compounds (A1) and open-chain trisubstituted amines (A2) as stabilizers instead of conventional water scavengers. These additives prevent flocculation through a different mechanism that does not consume NCO groups, thereby maintaining the NCO value while improving storage stability. The patent specifies using these additives in amounts of 0.01-5% by weight based on the total weight of the polyisocyanate mixture.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The phosphorus-containing acidic compounds and open-chain trisubstituted amines act as intermediary substances that mediate between the polyisocyanate and water, preventing the harmful interaction that leads to flocculation. These additives serve as a protective intermediary layer that stabilizes the system without requiring stoichiometric amounts like conventional water scavengers.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If high amounts of water scavengers are used to prevent hydrolysis, then prevention of amine formation is improved, but dilution effect reduces NCO groups and coatings properties

Engineering Contradiction:

Improveprevention of hydrolysisVSAvoidcoatings properties

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The invention changes the stabilization mechanism from stoichiometric water scavenging to substoichiometric additive stabilization. The phosphorus-containing acidic compounds and open-chain trisubstituted amines prevent hydrolysis and flocculation through a different chemical pathway that does not involve competing for water molecules, thus avoiding the dilution effect and preserving NCO group concentration for optimal coatings properties.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If para-toluenesulfonyl isocyanate is used as water scavenger, then water binding is improved, but reactivity with water is too high causing vigorous reaction and pressure build-up

Engineering Contradiction:

Improvewater binding capacityVSAvoidvigorous reaction and pressure build-up

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The phosphorus-containing acidic compounds and open-chain trisubstituted amines serve as milder intermediary stabilizers that prevent flocculation without the vigorous reactivity of para-toluenesulfonyl isocyanate. These additives provide water binding capacity through a controlled mechanism that does not cause rapid gas evolution or pressure build-up, making the system safer and easier to handle.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11807709B2Method for producing polyisocyanates of (cyclo)aliphatic diisocyanates which are flocculation-stable in solvents

Publication Date: 2023.11.07 BASF SE

AI summary

The present invention relates to a new process for preparing polyisocyanates containing isocyanurate groups and being flocculation-stable in solvents from (cyclo)aliphatic diisocyanates.