Cyclic Carbodiimide Sealing Agents for Polymers
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Solution Overview
Problem
Conventional carbodiimide compounds used as sealing agents for polymers with hydrolyzable functional groups, such as polyesters, polyamides, and polyurethanes, often produce volatile isocyanate compounds, leading to unpleasant odors and environmental degradation, and have low reactivity and high molecular weights that reduce their effectiveness.
Innovation Solution
Development of a cyclic carbodiimide compound with a specific molecular structure that reacts with acid groups without liberating isocyanate compounds, thereby preventing bad smells and enhancing reactivity and stability, including a process for producing these compounds through nitro compound reduction and triphenylphosphine reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If linear carbodiimide compounds are used as sealing agents, then acid groups can be sealed, but volatile isocyanate compounds are by-produced causing bad smell and environmental degradation
Solution Approach 1:
The patent changes the molecular structure parameter from linear to cyclic carbodiimide compound. This structural parameter change fundamentally alters the reaction pathway, allowing the carbodiimide to react with acid groups and form stable amide bonds without liberating volatile isocyanate compounds, thus eliminating the harmful byproduct while maintaining sealing effectiveness
Solution Approach 2:
The patent converts the potential harm of isocyanate liberation into a benefit by using the cyclic structure. The cyclic carbodiimide reacts with water or acid groups to directly form non-volatile products, transforming what would have been a harmful emission into a beneficial stable end product, improving both environmental performance and workability
2Object-generated harmful factors
If macrocyclic carbodiimide compounds with high molecular weight are used, then isocyanate liberation is prevented, but sealing efficiency decreases
Solution Approach 1:
The patent optimizes the molecular weight parameter of the cyclic carbodiimide compound, selecting a range (100-1000 g/mol) that balances two requirements: low enough to ensure high reactivity and diffusion capability for efficient sealing, but high enough to prevent volatile isocyanate liberation. This parameter optimization resolves the contradiction between efficiency and harm prevention
3Reliability
If conventional carbodiimide compounds are used, then acid group sealing is achieved, but reactivity is low and molecular weight is high reducing effectiveness
Solution Approach 1:
The patent changes the molecular structure from linear to cyclic form, which fundamentally alters the reactivity parameter. The cyclic structure creates ring strain and increases the electrophilicity of the carbodiimide carbon, significantly enhancing its reactivity toward acid groups and hydroxyl groups while maintaining appropriate molecular weight for effective sealing
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 cyclic carbodiimide compound effectively seals acid groups in polymers without producing isocyanate byproducts, improving the work environment and increasing the molecular weight of polymers, while maintaining stability and reactivity, making it suitable as both an end-sealing agent and a capture agent for acid groups.
Implementation Method 1
a carbodiimide compound having a cyclic structure reacts with an acid group, it does not liberate an isocyanate compound
Implementation Method 2
a process for producing the cyclic carbodiimide compound through nitro compound reduction and triphenylphosphine reactions
Data Source
AI summary
A cyclic carbodiimide compound which is useful as an end-sealing agent for polymer compounds. The cyclic carbodiimide compound is represented by the following formula (i): (in the above formula, X is a divalent group or a tetravalent group represented by the following formula (i-4). When X is divalent, q is 0 and when X is tetravalent, q is 1. Ar1 to Ar4 are each independently an aromatic group. They may be substituted by an alkyl group having 1 to 6 carbon atoms or phenyl group.)