Blocked Mercaptosilane Coupling Agents for Tire Rubber
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Solution Overview
Problem
Existing sulfur silane coupling agents used in tire compositions face issues such as high reactivity leading to premature curing and degradation under stress, along with odor and processing challenges, while less reactive alternatives do not achieve sufficient bonding with organic polymers.
Innovation Solution
Development of blocked mercaptosilane derivatives with multiple mercapto groups directly linked to the silicon atom through carbon-carbon bonds, which are initially non-reactive and can be activated during manufacturing using a deblocking agent to form multiple linkages with organic polymers, enhancing bonding and reducing degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If mercaptosilane coupling agents are used, then chemical reactivity with organic polymers is high and coupling is achieved at reduced loadings, but the chemical bonds are weaker and susceptible to breakage under high stress and frequency use conditions
Solution Approach 1:
The coupling agent molecule is segmented into multiple functional groups (multiple mercapto groups attached to silicon atom) that can independently bond with polymer chains. This segmentation allows distributed bonding across multiple sites, increasing overall bond strength and reliability under stress while maintaining low loading levels.
Solution Approach 2:
The invention creates a composite coupling structure where multiple C-S bonds are formed between a single silane molecule and multiple polymer chains. This composite bonding approach combines the strength of multiple individual bonds to overcome the weakness of single C-S bonds under high stress conditions.
2Manufacturing precision
If mercaptosilane coupling agents are used, then coupling efficiency is high, but premature curing (scorch) and unacceptably high viscosities during processing occur
Solution Approach 1:
The mercapto groups are pre-installed on the silane molecule during manufacturing, but their reactivity is blocked until the curing stage. This preliminary preparation allows the coupling agent to be incorporated into the rubber compound without causing premature curing, while still being ready to provide high coupling efficiency when activated.
Solution Approach 2:
The chemical state of the mercapto groups is changed from reactive to blocked (less reactive) form during processing, and then back to reactive form during curing. This parameter change controls the timing of the coupling reaction, preventing premature curing while ensuring efficient coupling at the appropriate stage.
3Ease of manufacture
If less reactive coupling agents (disulfide, thiocarbonyl, thioester) are used, then processing conditions improve and premature curing is reduced, but higher use levels are required and sufficient bonding is not achieved
Solution Approach 1:
The reactivity parameter of the coupling agent is dynamically controlled by blocking and unblocking the mercapto groups. During processing, the blocked form provides ease of manufacture and prevents premature curing. During curing, unblocking restores high reactivity to achieve sufficient bonding at low use levels, combining the advantages of both reactive and less reactive agents.
4Quantity of substance
If mercaptosilane coupling agents are used, then coupling at reduced loadings is achieved, but odor and processing challenges arise
Solution Approach 1:
The odor-causing mercapto groups are transformed into blocked forms that have reduced or eliminated odor during processing. The parameter change from reactive to blocked state reduces the harmful odor factor while maintaining the ability to provide effective coupling at low loadings when activated.
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 use of blocked mercaptosilanes minimizes coupling loss between rubber and coupling agent under stress, improves processing conditions, and maintains desirable properties like modulus and abrasion resistance without premature curing.
Implementation Method 1
more than one mercapto group is directly linked to the silicon atom through carbon-carbon bonds
Implementation Method 2
sulfur silane coupling agents for use in tire compositions... effect coupling at substantially reduced loadings
Implementation Method 3
Under high stress and/or high frequency use conditions, these chemical bonds are susceptible to breakage... The use of blocked mercaptosilanes minimizes coupling loss between rubber and coupling agent under stress
Data Source
AI summary
Sulfur silane coupling agents for use in tire compositions used to formulate tires or tire components which contain multiple blocked mercapto groups which are in a state of reduced activity until activated. The coupling agents are advantageously used in rubber formulations, including tire compositions, for example, for fabricating tires with low rolling resistance.