Non-crystallising Bis-oxazolidines Curing Agents

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Solution Overview

Problem

Polyoxazolidines with urethane groups tend to crystallize, which is disadvantageous for storage, transport, and application, and existing solutions using solvents impair mechanical properties and release VOCs, limiting the choice of suitable properties for polyurethanes.

Innovation Solution

A composition comprising polyoxazolidines with at least two urethane groups and one carbonato group, characterized by specific structural formulas, which are non-crystallizing and solvent-free, allowing for a broad range of properties and tailored curing properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polyoxazolidines with urethane groups are used as curing agents, then good curing properties are achieved, but they tend to crystallize which is disadvantageous for storage and transport

Engineering Contradiction:

Improvecuring propertiesVSAvoidstorage and transport

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent combines polyoxazolidines with urethane groups (POU) and polyoxazolidines with carbonato groups (POC) into a composite curing agent system. The POC component acts as a non-crystallizing base that prevents the POU component from crystallizing, while both components contribute to the curing properties. This composite approach allows the mixture to remain liquid during storage and transport yet still provide effective curing when applied.

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If solvents are used to prevent crystallization, then storage and transport properties are improved, but mechanical properties are impaired and VOCs are released

Engineering Contradiction:

Improvestorage and transportVSAvoidmechanical properties

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The polyoxazolidines with carbonato groups (POC) serve as an intermediary substance that prevents crystallization of the POU component without requiring external solvents. The POC acts as a molecular spacer and structure breaker that interferes with the crystallization process of POU, maintaining the mixture in a liquid state. This eliminates the need for harmful solvents while preserving mechanical properties.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If a narrow group of non-crystallizing compounds is used, then crystallization is prevented, but the choice of suitable properties is very restrictive

Engineering Contradiction:

Improvestorage and transportVSAvoidchoice of properties

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent divides the curing agent into two separate functional components: POU (polyoxazolidines with urethane groups) that provides curing properties, and POC (polyoxazolidines with carbonato groups) that provides non-crystallizing properties. This segmentation allows independent optimization of each component - POU can be selected for desired curing characteristics while POC is selected for liquid stability, and their combination provides both benefits simultaneously.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentEP2493949B1Non-crystallising bis-oxazolidines

Publication Date: 2016.03.16 SIKA TECH AG

AI summary

The present invention relates to non-crystallising oxazolidines as curing agents for polyisocyanates, respectively polyurethanes. These curing agents are essentially mixtures of at least one polyoxazolidine POU having at least two urethane groups and at least one polyoxazolidine POC having at least one carbonato group.