Silane Coupling Agents for Tire Rubber Stiffness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rubber mixtures for vehicle 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 property often lead to deterioration in another, and current silane coupling agents do not effectively enhance stiffness without compromising other physical properties.
Innovation Solution
A rubber compound comprising diene rubber, silica, and specific silanes (A and B) with empirical formulas A-I and A-XI, which improve stiffness and abrasion behavior while maintaining or improving rolling resistance and processability, by allowing silane A to bind to polymers through polysulfidic or reactive sulfur groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the network density of the vulcanized rubber compound is increased to improve handling behavior, then the stiffness and handling characteristics are improved, but the tear resistance and wet grip characteristics deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the silane coupling agent, specifically using a polysulfide silane with 2-8 sulfur atoms in the Sx group. This parameter change allows the silane to form crosslinks between silica particles and polymer chains, creating a dual-function coupling agent that simultaneously improves stiffness and maintains tear resistance by optimizing the network structure at the molecular level
Solution Approach 2:
The patent creates a composite coupling system where the silane molecule acts as a bridge between inorganic silica fillers and organic polymer matrices. The silane contains both silyl groups (for binding to silica) and polysulfide groups (for binding to polymers), forming a composite interface that transfers stress effectively while maintaining flexibility and tear resistance
2Strength
If the filler content is increased to improve handling behavior, then the stiffness is improved, but the rolling resistance increases
Solution Approach 1:
The patent optimizes the sulfur content parameter in the silane coupling agent (2-8 sulfur atoms), which changes the crosslinking density and type. This allows for improved stiffness through enhanced filler-polymer interaction while the specific polysulfide structure reduces hysteresis losses, thereby lowering rolling resistance compared to conventional monosulfide or disulfide couplings
3Strength
If a silane with reactive sulfur groups is used to bind to polymers, then the stiffness and handling characteristics are improved, but the processability may be affected
Solution Approach 1:
The silane coupling agent is incorporated into the rubber compound during the mixing and vulcanization process, where it preliminarily binds to both silica and polymer chains. This preliminary action occurs during standard processing, and the reactive sulfur groups are activated during vulcanization to form the crosslinked structure, ensuring good processability during mixing while achieving the desired stiffness in the final product
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 behavior, reduced heat buildup, improved rolling resistance, and low abrasion, with the combination of silanes A and B enhancing the rubber mixture's physical properties without compromising other attributes.
Implementation Method 1
silane A can also bind to polymers by reaction of the Sx or SH group or the S-SG group after removal of the protecting group during sulfur vulcanization
Implementation Method 2
advantages regarding the rolling resistance and processability of the rubber compound arise when the silica is bound 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 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 30 phf of at least one silane B having a general empirical formula B-I): B-I): (R1)oSi-R4-Si(R1)o, wherein x is a whole number from 2 to 10, q is equal to 0, 1, 2 or 3, and s is equal to 1, 2 or 3 and X is a hydrogen atom or -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.