Sulfonated Naphthalene Polyoxadiazole Polymer Flame Retardancy

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Solution Overview

Problem

There is a need for an easy method to prepare polyoxadiazole polymers with a high degree of sulfonation that enhances properties such as flame retardancy, UV stability, and dyeability, while maintaining comfort and durability in protective clothing and articles.

Innovation Solution

The method involves combining hydrazine, oleum, 2,6-naphthalene dicarboxylic acid, and optionally 4,4'-oxybis(benzoic acid) and terephthalic or isophthalic acid to form a reaction mixture, with oleum added in sufficient molar equivalents to produce sulfonated copolyoxadiazole polymers, which can be further sulfonated to achieve high sulfur content and specific structural units for improved properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sulfonated monomers and post-sulfonation methods are used to improve flammability, then flame retardancy is improved, but the complexity of the manufacturing process increases

Engineering Contradiction:

Improveflame retardancyVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines polymerization and sulfonation into a single step by using oleum as both the polymerization catalyst and sulfonating agent. This eliminates the need for separate polymerization and sulfonation steps, reducing manufacturing complexity while achieving high flame retardancy through sulfonation.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent performs sulfonation during the polymerization process rather than as a subsequent step. By introducing the sulfonating agent (oleum) in the polymerization step, the sulfonation occurs preliminarily as the polymer forms, simplifying the overall process while maintaining high flame retardancy.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If multiple steps of oleum addition are used to prepare polyoxadiazole copolymer, then polymerization is achieved, but the ease of manufacture decreases

Engineering Contradiction:

Improvepolymerization completenessVSAvoidprocess simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the polymerization and sulfonation functions into a single reaction step using oleum as both catalyst and sulfonating agent. This eliminates multiple addition steps while ensuring complete polymerization and high sulfonation content, improving ease of manufacture.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If high degree of sulfonation is achieved through extensive post-sulfonation, then flame retardancy and UV stability are improved, but the loss of time increases

Engineering Contradiction:

Improveflame retardancy and UV stabilityVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent performs sulfonation during the polymerization step rather than as a subsequent post-treatment. This preliminary sulfonation action achieves high flame retardancy and UV stability in a single step, eliminating time-consuming separate sulfonation steps.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent maintains continuous sulfonation activity during the polymerization process by using oleum as both catalyst and sulfonating agent. This continuous action ensures high sulfonation content is achieved during polymer formation rather than requiring separate post-sulfonation treatment, reducing total processing time.

Inventive Principle:

Principle #20Continuity of useful action

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 process results in polymers with a limiting oxygen index of 24 or greater, offering enhanced flame retardancy and UV stability, along with good dyeability, making them suitable for high-performance fibers and protective textiles.

Implementation Method 1

Another method is the use of oleum during polymerization to sulfonate the polymer as it is prepared

Methodology Applied

Scientific EffectSulfonation:

Implementation Method 2

reacting aromatic dicarboxylic acids with hydrazine sulfate in a limited amount of oleum

Methodology Applied

Scientific EffectCondensation reaction:

Data Source

PatentEP2861649B1Sulfonated naphthalene polyoxadiazole polymers

Publication Date: 2019.07.24 EI DU PONT DE NEMOURS & CO

AI summary

Described are sulfonated naphthalene polyoxadiazole polymers with a high degree of sulfonation and good flammability properties. The polymer has repeat units of Formula (I) and one or both of Formula (II) and (IIa); wherein Q is SO3M and M is a cation. The polymers are useful in articles such as fibers.