Silane Coupling System for Tire Rubber Mixture
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Solution Overview
Problem
Existing rubber mixtures for tires face challenges in balancing properties such as wet grip, dry braking, handling, rolling resistance, winter performance, abrasion, and tear resistance, where improvements in one characteristic often lead to deterioration in others, and current silane coupling agents do not effectively enhance hysteresis and tear properties without affecting other physical properties.
Innovation Solution
A rubber mixture comprising diene rubber, silica, and a specific combination of silanes A and B with molecular formulas A-I) and A-XI), where silane A can bind to polymers due to its polysulfidic S group, and silane B does not bind, optimizing hysteresis behavior and tear properties while maintaining comparable hardness and other physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the network node density of the vulcanized rubber mixture 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 of the silane coupling agent system by introducing a specific ratio of polysulfidic silane (with Sx groups where x≥2) to monosulfidic silane. This parameter change in the coupling agent chemistry modifies the crosslinking mechanism to achieve optimal balance between handling behavior and tear properties without excessive network density
Solution Approach 2:
The patent uses a composite silane coupling system combining two different silane types (polysulfidic and monosulfidic) in specific ratios. This composite approach creates a multi-functional coupling system that simultaneously optimizes handling behavior through appropriate network formation while preserving tear properties through controlled crosslinking density
2Loss of energy
If silica is bonded to the polymer using silane coupling agents to improve rolling resistance behavior and processability, then rolling resistance and processability are improved, but hysteresis behavior and tear properties are not sufficiently enhanced
Solution Approach 1:
The patent optimizes the sulfur content parameter in the silane coupling agent by specifying Sx groups with x≥2, which provides sufficient sulfur for polymer binding while controlling the crosslinking density. This parameter optimization enables improved rolling resistance through better silica-polymer bonding while simultaneously enhancing tear properties through appropriate network formation
Solution Approach 2:
The patent applies different silane functions locally: the polysulfidic silane (with Sx groups) provides both silica coupling and polymer crosslinking capabilities for improved tear properties, while the monosulfidic silane provides gentle silica coupling for rolling resistance optimization. This local differentiation of silane functions resolves the contradiction
3Ease of operation
If an increase in filler content is made to improve handling behavior, then handling behavior is improved, but rolling resistance increases
Solution Approach 1:
The patent changes the quality parameter of the filler-polymer interface by using optimized silane coupling agents with specific Sx groups. This improves the effectiveness of filler incorporation, allowing adequate handling behavior with lower filler content, thereby reducing rolling resistance while maintaining handling performance
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 mixture achieves optimal rolling resistance behavior and longer structural durability under stress, with improved hysteresis and tear properties without negatively impacting other tire characteristics, making it suitable for various tire components and technical rubber articles.
Implementation Method 1
silanes that, in addition to a silyl group, have a reactive sulfur group, such as in particular an Sx group (with x ≥ 2) or have a mercapto group S-H or blocked S-SG group, where SG stands for protecting group, so that the silane is formed by reaction of the Sx or S-H group or the S-SG group after removal of the protecting group can also bind to polymers during sulfur vulcanization
Implementation Method 2
there are advantages in terms of rolling resistance behavior and the processability of the rubber mixture if the silica is bonded to the polymer (s) using silane coupling agents
Implementation Method 3
at least one diene rubber; and 1 to 30 phf of at least one silane A with the general molecular formula A-I) and/or A-XI)
Data Source
AI summary
The invention relates to a sulfur-crosslinkable rubber mixture, the vulcanizate thereof, and a vehicle tyre. The a sulfur-crosslinkable rubber mixture contains at least the following constituents: at least one diene rubber; and 10 to 300 phr of at least one silicic acid: and 1 to 30 phf of at least one silane A having a general empirical formula A-I) and/or A-XI) A-I) (R1)oSi-R2-(S-R3)q-Sx-(R3-S)q-R2-Si(R1)o; A-XI) (R1)oSi-R2-(S-R3)s-S-X; and - 0.5 to 30phf of at least one silane B having a general empirical formula B-I) B-I) (R1)oSi-R4-S-R4-Si(R1)o wherein x represents a whole number from 2 to 10, q is equal to 1, 2 or 3, and s is equal to 0, 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, C6-C20-aryl groups, C2-C20-alkenyl groups and C7-C20-aralkyl groups.