Rubber composition including a functionalised polybutadiene
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Solution Overview
Problem
Snow tires face challenges in balancing rolling resistance, wet grip, and abrasion resistance, with existing compositions compromising on these performance metrics due to low glass transition temperature rubber and high reinforcing filler levels.
Innovation Solution
A rubber composition based on functionalized polybutadiene, obtained through a process involving homopolymerization with a catalytic system containing rare earth metals and a crosslinking system, which enhances the tire's performance by improving cold creep resistance and maintaining grip on snowy and wet surfaces while reducing rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high levels of reinforcing inorganic filler are used to improve snow grip, then snow grip is improved, but rolling resistance increases
Solution Approach 1:
The patent optimizes the silica filler content to a specific range (40-200 phr, preferably 60-150 phr) and controls the sulfur content (0.5-12 phr) to achieve optimal crosslinking density, balancing reinforcement for snow grip with sufficient flexibility to maintain low rolling resistance
Solution Approach 2:
The patent uses silica that is treated with specific coupling agents (triethoxysilane, trisulfide) to create localized regions of enhanced filler-rubber interaction at the filler surface, improving reinforcement efficiency at lower overall filler loadings, thereby reducing rolling resistance while maintaining snow grip
2Reliability
If softer rubber compound is used to improve grip on snowy ground, then snow grip is improved, but abrasion resistance deteriorates
Solution Approach 1:
The patent controls the hardness/softness by adjusting the elastomer composition (using polybutadiene with 1,2-vinyl groups and polyisoprene) and sulfur content (0.5-12 phr) to achieve optimal crosslinking density, creating a compound that is soft enough for snow grip but sufficiently crosslinked to maintain abrasion resistance
Solution Approach 2:
The patent incorporates silica filler (40-200 phr) with specific surface treatment to create a composite structure where the filler network provides reinforcement and abrasion resistance while the elastomer matrix maintains softness for snow grip, achieving both properties simultaneously
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 composition achieves improved rolling resistance, grip on snowy and wet surfaces, and abrasion resistance, making it suitable for snow tires without compromising on other performance metrics.
Implementation Method 1
homopolymerizing butadiene using a catalytic system to form a pseudo-living elastomer, said catalytic system being based on at least: a conjugated diene monomer, a salt of one or more rare earth metals of an organic phosphoric acid, an alkylating agent comprising aluminum, and a halogen donor comprising an alkylaluminum halide
Implementation Method 2
adding to the pseudo-living elastomer formed in step (a) a polyfunctional compound, comprising at least three functional groups, said functional group being capable of reacting on the reactive end of the pseudo-living elastomer
Implementation Method 3
adding to the mixture formed in step (b) a functionalizing agent corresponding to the formula A-Ri-B with A designating a group capable of reacting on the reactive end of the pseudo-living elastomer, Ri designating an atom or a group of atoms forming a bond between A and B, and B designating a function capable of reacting with a reinforcing filler
Implementation Method 4
a crosslinking system, in which the functionalized polybutadiene is capable of being obtained by a process
Data Source
AI summary
The invention relates to a rubber composition having an improved performance trade-off between roll resistance, grip on snow-covered terrain, grip on wet surfaces and wear resistance. Said composition is made from an elastomer matrix comprising a functionalised polybutadiene, at least one reinforcing filler, and a cross-linking system in which the functionalised polybutadiene can be produced using a specific method. The invention also relates to a pneumatic or non-pneumatic tyre comprising said composition.