RAFT Agent with Protected Mercapto Group for Rubber
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Solution Overview
Problem
Existing RAFT agents used in rubber mixtures for pneumatic tires and other applications result in a high number of free chain ends, leading to increased energy loss and heat buildup, which negatively affects the rolling resistance of the rubber compound.
Innovation Solution
A RAFT agent with a specific chemical structure that includes a protected mercapto group, which participates in vulcanization, reducing the number of free chain ends and improving the rolling resistance behavior of the vulcanized rubber mixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional RAFT agents are used in rubber mixtures, then polymerization control is achieved, but the number of free chain ends increases leading to higher energy loss and heat buildup
Solution Approach 1:
The patent introduces a protecting group as an intermediary that temporarily masks the mercapto group during polymerization, preventing it from forming free chain ends. The protecting group is then removed after polymerization to reveal the functional mercapto group, thus mediating between the need for polymerization control and the need to minimize free chain ends
Solution Approach 2:
The patent applies preliminary protection of the mercapto group before polymerization occurs. By pre-installing the protecting group on the RAFT agent, the invention prevents the formation of harmful free chain ends during the polymerization process, and then removes the protection afterward to achieve the desired final structure
2Stability of the object's composition
If conventional RAFT agents are used in rubber mixtures, then polymerization control is achieved, but heat buildup increases negatively affecting rolling resistance
Solution Approach 1:
The protecting group acts as an intermediary that prevents the mercapto group from participating in unwanted reactions during polymerization, thereby reducing heat buildup. After polymerization, the protecting group is removed to reveal the functional mercapto group, thus mediating between polymerization control and temperature management
Solution Approach 2:
The patent converts the potentially harmful effect of the mercapto group (which would create free chain ends and heat buildup) into a beneficial outcome by temporarily protecting it during polymerization. The protection prevents harm, and the subsequent deprotection creates the desired functional group that improves rolling resistance
3Productivity
If free chain ends are present in the rubber compound, then polymerization is complete, but rolling resistance deteriorates due to energy damping
Solution Approach 1:
The protecting group serves as an intermediary that prevents the formation of free chain ends during polymerization by masking the mercapto group. After polymerization is complete, the protecting group is removed to reveal the functional mercapto group, thus mediating between achieving complete polymerization and eliminating harmful free chain ends that affect rolling resistance
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 RAFT agent reduces the number of free chain ends, thereby minimizing energy loss and heat buildup, enhancing the rolling resistance and performance of the rubber compound in applications like vehicle tires.
Implementation Method 1
The Reversible Addition Fragmentation Chain Transfer (RAFT) process is a promising method for carrying out controlled radical polymerizations
Implementation Method 2
the component contains a polymer blend of a copolymer and another polymer. The polymers may include components, in particular functional groups, based on a thiocarbonylthio-RAFT reaction
Data Source
Figure 1~3
AI summary
The invention relates to a RAFT agent, a method for polymerizing alkenes and/or dienes and/or vinyl compounds and/or vinylidene compounds using at least one RAFT agent, a polymer synthesized using said method, a sulfur cross-linkable rubber mixture, and the use of the sulfur cross-linkable rubber mixture for manufacturing pneumatic vehicle tires, straps, belts or tubes. According to a preferred embodiment, the RAFT agent is represented by formula Z-C(=S)-S-R-S-P (I), where Z is a Z group typical for RAFT polymerization, R is an R group typical for RAFT polymerization, C is a carbon atom, S is a sulfur atom, and P is a protective group selected from among the group comprising: S(=0)2-R1, where R1 = alkyl, benzyl or phenyl; and/or S-C(=S)-N-R2R3, where R2 and R3 = alkyl, benzyl or phenyl; and/or C(=0)-R4, where R4 = alkyl; and/or N-R5R6, where R5 = hydrogen atom (H), alkyl, benzyl or phenyl and R6 = alkyl, benzyl or phenyl; and/or SiR7R8R9, where R7, R8 and R9 = alkyl or benzyl; and/or S(=0)2-OM, where M = Na, K or H.