Sulfur-Crosslinkable Rubber Mixture Handling and Rolling Resistance
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Solution Overview
Problem
Existing rubber mixtures for vehicle tires face challenges in balancing properties such as rigidity, hardness, rolling resistance, and heat build-up, often requiring trade-offs between these factors, which affects handling and other performance indicators.
Innovation Solution
A rubber compound comprising diene rubber, silica, and a specific combination of silanes A and B with reactive sulfur groups, which improves handling and rolling resistance while maintaining other properties at an acceptable level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the network node density of the vulcanized rubber compound is increased to improve handling behavior, then handling behavior is improved, but tear properties and wet grip indicators deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters by introducing silane A with reactive sulfur groups (Sx or SH) that can bond to both silica and polymer chains. This creates a dual-function coupling agent that modifies the network structure to achieve improved handling (higher stiffness) while maintaining tear resistance through optimized crosslinking density and distribution.
Solution Approach 2:
The patent creates a composite system where silane A acts as a bridge between inorganic silica fillers and organic polymer matrices. This composite approach allows simultaneous optimization of multiple properties: the silica-silane-polymer network provides both the stiffness needed for handling and the distributed bonding that prevents tear propagation.
2Force
If the filler content is increased to improve handling behavior, then handling behavior is improved, but rolling resistance increases
Solution Approach 1:
The patent modifies the filler-polymer interaction parameters by using silane A as a coupling agent. This chemical bonding reduces the interfacial friction and energy loss between filler particles and polymer matrix, allowing high filler content to be used for improved handling without the penalty of increased rolling resistance.
Solution Approach 2:
Silane A serves as an intermediary substance that chemically connects silica fillers to polymer chains. This mediator reduces the harmful friction and energy dissipation at the filler-polymer interface, enabling high filler loading to improve handling while maintaining low rolling resistance.
3Loss of energy
If silica is bonded to polymers by silane coupling agents to improve rolling resistance and processability, then rolling resistance and processability are improved, but handling behavior and heat build-up are not sufficiently optimized
Solution Approach 1:
The patent makes silane A a multi-functional coupling agent that simultaneously: (1) bonds to silica through silyl groups, (2) bonds to polymer chains through reactive sulfur groups (Sx or SH), (3) reduces rolling resistance through improved interface, and (4) enhances handling behavior through optimized network structure. This universal approach resolves the previous trade-off between rolling resistance and handling.
Solution Approach 2:
The patent changes the chemical reactivity parameters of the silane coupling agent by incorporating reactive sulfur groups (Sx with x≥2 or SH groups). This modification enables the silane to participate in sulfur vulcanization and form strong bonds with diene rubber polymers, thereby improving handling behavior and heat build-up characteristics while maintaining rolling resistance benefits.
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 rubber compound achieves optimized handling and rolling resistance with reduced heat build-up, maintaining other tire properties at comparable levels, as demonstrated by improved dynamic storage modulus and rebound resilience.
Implementation Method 1
the silane can be protected by reaction of the S x - or S-H moiety or the S-SG moiety after removal of the Protective group can also attach to polymers during sulfur vulcanization
Implementation Method 2
it has been found that the combination of silanes A and B, where silane A can also bond to polymers due to the reactive S-X group
Implementation Method 3
there are advantages with regard to the rolling resistance behavior and the processability of the rubber mixture if the silica is bonded to the polymer(s) by means of silane coupling agents
Data Source
AI summary
The invention relates to a sulfur-crosslinkable rubber mixture, the vulcanizate thereof, and a vehicle tyre. The sulfur-crosslinkable rubber mixture contains at least the following constituents: - at least one diene rubber; and 10 to 300 phr of at least one silica acid; and 1 to 30 phf of at least one silane A having the general empirical formula A-I) A-I)(R1)oSi-R2-(S-R3)q-S-X; and 0.5 to 30 phf of at least one silane B having the general empirical formula B-I) B-I) (R1)oSi-R2-(S-R3)u-S-R2-Si(R1)o wherein q =1, 2 or 3; and u = 1, 2 or 3; and X is a hydrogen atom or a –C(=O)-R8 group, wherein R8 is selected from hydrogen, C1-C20 alkyl groups, preferably C1-C17, C6-C20- aryl groups, preferably phenyl, C2-C20-alkenyl groups and C7-C20-aralkyl groups.