Tire Tread Rubber Composition for Rolling Resistance and Scorch Control
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Solution Overview
Problem
Existing rubber mixtures for vehicle tires face challenges in balancing improved rolling resistance with maintaining other tire properties such as wet grip, dry braking, and abrasion resistance, while also requiring optimal vulcanization times to prevent scorching and ensure energy efficiency in the manufacturing process.
Innovation Solution
A sulfur-crosslinkable rubber mixture is developed, featuring terminally modified liquid polybutadiene with a weight average molecular weight of 500 to 12,000 g/mol, combined with diene rubber, silica, and blocked mercaptosilane, which enhances rolling resistance and vulcanization times, reducing the risk of scorching and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid polybutadiene is used as a replacement for conventional plasticizer oils in tread compounds, then winter properties and grip are improved, but dry braking and handling performance deteriorate
Solution Approach 1:
The patent applies parameter changes by carefully controlling the molecular weight (Mw ≤ 12,000 g/mol) and vinyl content (30-70%) of the liquid polybutadiene, as well as its saturation level (0-50%). These specific parameter ranges optimize the balance between low-temperature flexibility (improving winter properties) and high-temperature stability (maintaining dry braking performance). The controlled saturation and molecular weight prevent excessive softening that would harm handling while retaining enough liquidity to improve winter grip.
Solution Approach 2:
The patent creates a composite material system by combining liquid polybutadiene with specific rubber compounds (natural rubber, styrene-butadiene rubber, polybutadiene rubber) and fillers (silica, carbon black) in precisely defined ratios. This composite approach allows the liquid polybutadiene to provide winter grip enhancement while the surrounding rubber matrix and filler system maintain structural integrity and dry braking performance, resolving the contradiction between improved winter properties and maintained handling characteristics.
2Strength
If prolonged heating is applied during vulcanization to ensure complete cross-linking, then structural durability is improved, but energy consumption increases and scorching risk rises
Solution Approach 1:
The patent applies preliminary action by incorporating peroxide-precrosslinked silica particles into the rubber compound before vulcanization. This precrosslinking creates initial crosslink bridges that facilitate faster and more uniform sulfur crosslinking during the subsequent vulcanization process. As a result, complete cross-linking is achieved more rapidly, reducing both energy consumption and the risk of scorching while ensuring structural durability.
Solution Approach 2:
The patent uses peroxide-precrosslinked silica as an intermediary that mediates between the rubber polymer chains and the sulfur crosslinking system. The precrosslinked silica particles act as nucleation sites and crosslinking accelerators, enabling more efficient sulfur crosslinking that requires less time and energy while producing durable vulcanizates with reduced scorching risk.
3Use of energy by stationary object
If rapid crosslinking is attempted to reduce heating time and energy consumption, then energy efficiency improves, but scorching susceptibility increases
Solution Approach 1:
The patent applies preliminary action by pre-crosslinking the silica with peroxide before incorporating it into the rubber compound. This precrosslinked silica structure acts as a controlled crosslinking template that guides the subsequent sulfur crosslinking process, enabling rapid yet controlled crosslinking that reduces heating time and energy consumption while preventing uncontrolled premature crosslinking (scorching).
Solution Approach 2:
The peroxide-precrosslinked silica serves as an intermediary that mediates the crosslinking kinetics. It provides controlled crosslinking sites that accelerate the vulcanization process for energy efficiency while the stable precrosslinked structure prevents runaway crosslinking reactions that cause scorching, thus resolving the contradiction between rapid crosslinking and scorching susceptibility.
4Loss of energy
If silica is used to replace carbon black filler, then rolling resistance is improved, but wet grip and dry braking performance may deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the silica particle characteristics (average particle diameter 7-20 nm, BET surface area 150-400 m²/g) and its surface treatment with liquid polybutadiene and peroxide precrosslinking. These parameter optimizations reduce silica's inherent tendency to deteriorate wet grip and dry braking while maintaining its rolling resistance benefits. The controlled surface treatment improves silica-rubber interfacial adhesion, ensuring grip performance is not compromised.
Solution Approach 2:
The patent creates a composite filler system by combining peroxide-precrosslinked silica with carbon black (in some embodiments) and liquid polybutadiene surface treatment. This composite approach allows the silica to provide rolling resistance reduction while the carbon black and surface-treated silica work synergistically to maintain wet grip and dry braking performance, resolving the contradiction between energy efficiency and grip reliability.
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 improved rolling resistance with maintained tire properties, allowing for cost-effective and energy-efficient tire production without compromising on vulcanization times or tire durability.
Implementation Method 1
a sulfur-crosslinkable rubber mixture which enables an improvement in rolling resistance while maintaining other tire properties, and in addition the heating times are to be improved so that a moderate time for heating the tire is possible without a simultaneous susceptibility to scorch
Implementation Method 2
at least one liquid polybutadiene which is terminally organosilicon-modified and has a weight average molecular weight Mw according to GPC of 500 to 12000 g/mol
Implementation Method 3
A crucial aspect is the duration of the heating required for vulcanization of the rubber compound during the manufacturing process
Data Source
AI summary
The invention relates to a sulfur-crosslinkable rubber compound, in particular for treads of vehicle tires, and to a vehicle tire. The rubber compound contains: - at least one diene rubber and - at least one silica and - 3 to 15 ph of at least one blocked and/or unblocked mercaptosilane and - 1 to 40 phr of at least one liquid polybutadiene, which is terminally organosilicon-modified, and has a weight average Mw of the molecular weight according to GPC of 500 to 12000 g/mol.