Devulcanized Rubber Composition With Controlled Vulcanizing Time
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Solution Overview
Problem
Conventional devulcanization techniques using amine compounds as devulcanizing agents result in significantly shortened vulcanizing or scorch times, limiting the processability of rubber compositions, and are limited to EPDM-based rubbers, restricting the types of vulcanized rubber that can be reused.
Innovation Solution
The use of a devulcanizing agent with an alkylsulfonamide group, such as sulfonamidation of long-chain alkylamines, to mix with vulcanized rubbers like diene-based rubbers, allowing for controlled vulcanizing times and improved processability by applying a shearing force at controlled temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an amine compound is used as a devulcanizing agent, then devulcanization of sulfur-cured rubber can be achieved, but vulcanizing time and scorch time are significantly shortened, reducing processability
Solution Approach 1:
The patent changes the chemical structure parameter of the devulcanizing agent from an amine compound to a carbamate compound. This structural parameter change reduces the basicity of the devulcanizing agent, thereby preventing excessive shortening of vulcanizing time and scorch time while maintaining devulcanization capability. The carbamate structure modifies the interaction with sulfur crosslinks, achieving a balance between devulcanization effectiveness and preservation of vulcanization characteristics.
2Ease of manufacture
If an amine compound is used as a devulcanizing agent, then devulcanization can be achieved, but the type of rubber is limited to EPDM-based rubbers
Solution Approach 1:
The patent achieves universality by developing a carbamate-based devulcanizing agent that can effectively devulcanize multiple types of vulcanized rubber including natural rubber, synthetic rubber, and EPDM rubber. The carbamate structure provides broad compatibility with different rubber matrices and sulfur crosslinking systems, eliminating the limitation to only EPDM-based rubbers and enabling wide applicability across various rubber types.
3Ease of repair
If a devulcanized rubber is added to a rubber composition, then rubber waste can be reused, but processability is reduced due to significantly shorted vulcanizing time
Solution Approach 1:
The patent changes the chemical parameter of the devulcanizing agent from amine to carbamate structure, which moderates the basicity and thereby controls the extent of vulcanizing time reduction. This allows rubber waste to be effectively reused through devulcanization while maintaining sufficient vulcanizing time and scorch time for good processability during subsequent processing operations.
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 devulcanized rubber compositions exhibit excellent processability and post-vulcanization physical properties, enabling their use in rubber parts of pneumatic tires with optimized vulcanizing times.
Implementation Method 1
a devulcanized rubber obtained by mixing a devulcanizing agent having an alkylsulfonamide group and a vulcanized rubber
Implementation Method 2
allowing for controlled vulcanizing times and improved processability by applying a shearing force at controlled temperatures
Data Source
AI summary
The present invention relates to a devulcanized rubber obtained by mixing a devulcanizing agent having an alkylsulfonamide group and a vulcanized rubber. The devulcanizing agent preferably contains a sulfonamide compound of an alkylamine having 12 or more carbon atoms. The present invention also relates to a rubber composition comprising the devulcanized rubber. The rubber composition preferably contains 1 to 30 parts by mass of the devulcanized rubber per 100 parts by mass of a total amount of an unvulcanized rubber component in the rubber composition.