Switchable RAFT Agent Copolymerization for Tire Rubber
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Solution Overview
Problem
The selection of suitable monomers for polymers in vehicle tires is limited due to sulfur crosslinking, requiring C=C double bonds, and existing methods do not effectively improve heat build-up indicators like rolling resistance behavior.
Innovation Solution
A process for co-polymerization using dienes with alkenes, vinyl acetate, acrylic acid derivatives, and methacrylic acid derivatives, employing a switchable RAFT agent (N-methyl-N-(4-pyridinyl)dithiocarbamates) to produce novel sulfur-crosslinkable copolymers with adjustable structures for improved tire properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional monomers (dienes, styrene) are used for sulfur crosslinking in vehicle tires, then the polymer chains contain C=C double bonds enabling crosslinking, but the heat build-up indicators and rolling resistance behavior cannot be improved
Solution Approach 1:
The patent changes the chemical parameters of the polymer by incorporating monomers with C=C bonds in side groups (vinyl acetate, acrylic acid derivatives, methacrylic acid derivatives) rather than only in the main chain. This allows sulfur crosslinking to occur through side group double bonds while using diverse monomer compositions, thereby improving rolling resistance behavior without limiting monomer selection
Solution Approach 2:
The patent creates composite polymer structures by co-polymerizing dienes with monomers containing side group C=C bonds (vinyl acetate, acrylic acid derivatives, methacrylic acid derivatives). This composite approach combines the sulfur crosslinking capability from side group double bonds with the mechanical properties of diene polymers, achieving improved rolling resistance while maintaining versatility in monomer selection
2Strength
If monomers with C=C double bonds are selected for sulfur crosslinking, then crosslinking during vulcanization is enabled, but the selection of suitable monomers is limited
Solution Approach 1:
The patent shifts the location of C=C bonds from the main polymer chain to side groups of the polymer backbone. By using monomers like vinyl acetate, acrylic acid derivatives, and methacrylic acid derivatives, the double bonds are positioned in side groups where they can participate in sulfur crosslinking. This parameter change enables a broader range of monomers to be used while maintaining crosslinking capability
Solution Approach 2:
The side group C=C bonds act as intermediaries that enable sulfur crosslinking without requiring the main polymer chain to contain double bonds. This intermediary mechanism allows diverse monomers (including those without main chain double bonds) to be incorporated while still achieving the necessary crosslinking for vulcanization
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 process results in copolymers that optimize rolling resistance behavior and other properties of rubber mixtures in vehicle tires by incorporating unusual monomers like ethene and vinyl acetate, enhancing the performance of tire compounds.
Implementation Method 1
The Reversible Addition Fragmentation Chain Transfer process (RAFT) is a promising method for carrying out controlled radical polymerizations
Implementation Method 2
due to sulfur crosslinking during the vulcanization of tire compounds, C=C double bonds must be contained along the polymer chain
Data Source
Figure 1~3
AI summary
The invention relates to a method for the copolymerization of dienes using at least one RAFT agent, a copolymer produced by the method, a sulfur-crosslinkable rubber compound, and the use of the sulfur-crosslinkable rubber compound for the production of vehicle pneumatic tires, belts, straps, or hoses.In the process for the co-polymerization of at least one monomer of group A) consisting of dienes with at least one monomer of group B) selected from the group consisting of alkenes, vinyl acetate, acrylic acid derivatives and methacrylic acid derivatives, at least one switchable RAFT agent from the group of N-methyl-N-(4-pyridinyl)dithiocarbamates according to formula I) is used: where R is an R group typical for RAFT polymerization, and where H+ represents a proton, and where the form of the agent shown on the right is obtained by adding a proton donor (acid) and the form of the agent shown on the left is obtained by adding a proton acceptor (base).