Sulfur-Crosslinked Rubber Desulfurization with Selective Sulfur Bond Cleavage

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Solution Overview

Problem

Existing desulfurization methods for sulfur-crosslinked rubber face issues such as odor generation from desulfurization agents, deterioration in physical properties, and difficulty in restoring the rubber to its virgin state, particularly due to high-temperature conditions and non-selective cleavage of the rubber main chain.

Innovation Solution

A desulfurization method using primary and secondary phosphine oxides, sulfenic acid, and sulfinic acid as desulfurization agents, combined with shear force and controlled heating, to selectively cleave sulfur bonds while minimizing odor and maintaining rubber integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If shear desulfurization is used to desulfurize sulfur-crosslinked rubber, then desulfurization can be carried out, but physical properties deteriorate due to non-selective cleavage of rubber main chain

Engineering Contradiction:

Improvedesulfurization effectivenessVSAvoidphysical properties

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent replaces mechanical shear force with chemical desulfurization agents (phosphine oxides, sulfenic acid, sulfinic acid) to selectively break sulfur bonds. This substitution allows desulfurization to proceed through chemical reaction rather than mechanical stress, preventing non-selective cleavage of the rubber main chain and preserving physical properties while achieving effective desulfurization.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the desulfurization mechanism from mechanical (shear force) to chemical (phosphine oxide-based reagents). By altering the fundamental parameter of the desulfurization process, the method achieves selective bond cleavage of sulfur crosslinks without damaging the rubber polymer backbone, thus maintaining physical properties while improving desulfurization reliability.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conventional desulfurization agents are used, then desulfurization can be achieved, but odor is generated during and after desulfurization

Engineering Contradiction:

Improvedesulfurization capabilityVSAvoidodor

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition of desulfurization agents from conventional options (disulfide compounds, thiol compounds, amine compounds) to phosphine oxides and their analogs. This parameter change in the chemical reagent type eliminates odor generation during the desulfurization process and in the final regenerated rubber, while maintaining effective desulfurization capability through the unique chemical mechanism of phosphine oxide-based agents.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If high-temperature conditions are used for desulfurization, then desulfurization can be carried out, but main chain cleavage occurs and physical properties deteriorate

Engineering Contradiction:

Improvedesulfurization rateVSAvoidphysical properties

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent replaces thermal energy with chemical energy by using phosphine oxide-based desulfurization agents. This substitution allows desulfurization to proceed at lower temperatures through chemical reaction mechanisms, eliminating the need for high-temperature conditions that cause main chain cleavage and physical property deterioration, while maintaining effective desulfurization rates.

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

Effectively desulfurizes sulfur-crosslinked rubber by reducing odor and preserving physical properties, enabling the production of a reusable regenerated rubber with improved properties.

Implementation Method 1

a primary phosphine oxide and a secondary phosphine oxide and an analog of the phosphine oxide; a primary phosphine and a secondary phosphine which become oxides when oxidized and an analog of the phosphine; a sulfenic acid; and a sulfinic acid, as a desulfurization agent which acts on a sulfur bond in the sulfur-crosslinked rubber and cleaves the sulfur bond

Methodology Applied

Scientific EffectNucleophilic attack: Chemical Bonding

Implementation Method 2

applying a shear force and heating

Methodology Applied

Scientific EffectShear stress: Shear Stress

Implementation Method 3

applying a shear force and heating

Methodology Applied

Scientific EffectHeating: Heating

Data Source

PatentUS20250376544A1Desulfurization method for sulfur-crosslinked rubber

Publication Date: 2025.12.11 TOYODA GOSEI CO LTD

AI summary

A desulfurization method for a sulfur-crosslinked rubber, including: adding, to the sulfur-crosslinked rubber, at least one selected from the group consisting of a primary phosphine oxide and a secondary phosphine oxide and an analog of the phosphine oxide; a primary phosphine and a secondary phosphine which become oxides when oxidized and an analog of the phosphine; a sulfenic acid; and a sulfinic acid, as a desulfurization agent which acts on a sulfur bond in the sulfur-crosslinked rubber and cleaves the sulfur bond; and applying a shear force and heating.