Rubber Composition for Balanced On-Ice Grip and Abrasion Resistance
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Solution Overview
Problem
Conventional rubber compositions for tires face a trade-off between on-ice performance and abrasion resistance, with soft tread rubber enhancing on-ice grip but compromising abrasion resistance on common road surfaces.
Innovation Solution
A rubber composition comprising 100 parts by mass of a rubber component with 45 to 75% natural rubber and 25 to 55% conjugated diene-based polymer, along with a non-modified conjugated diene-based polymer and a filler, where the bonded styrene amount is 25% or less, and the bonded vinyl amount is 20% or more, to achieve a balance between on-ice performance and abrasion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tread rubber is softened to enhance on-ice performance, then the on-ice grip property is improved, but the abrasion resistance on common road surfaces deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the rubber by incorporating a specific type of conjugated diene-based polymer with controlled molecular weight (5,000-40,000) and specific microstructure (bonded styrene <10%, bonded vinyl ≥20%). This parameter optimization allows the rubber to achieve both softness for on-ice grip and sufficient durability for abrasion resistance, resolving the trade-off between these two properties.
Solution Approach 2:
The invention creates a composite rubber system by combining natural rubber (45-75 parts) with a specifically designed conjugated diene-based polymer (1-40 parts) and other conventional rubber components. This composite structure leverages the advantages of each component: natural rubber provides good on-ice performance while the conjugated diene polymer contributes to abrasion resistance, achieving a balance that neither component could achieve alone.
2Duration of action of stationary object
If the bonded styrene amount is increased to improve abrasion resistance, then the durability is improved, but the on-ice performance deteriorates
Solution Approach 1:
The invention precisely controls the bonded styrene amount to be less than 10% in the conjugated diene-based polymer, which is significantly lower than conventional SBR (styrene-butadiene rubber) that typically contains 23-25% bonded styrene. This low styrene content minimizes the negative impact on on-ice performance while the specific molecular weight and vinyl content provide sufficient abrasion resistance, thus resolving this contradiction.
Solution Approach 2:
The invention applies local quality by creating a rubber composition with non-uniform microstructure through the use of conjugated diene-based polymer with specific local bonding characteristics (bonded vinyl ≥20%). This localized vinyl bonding provides abrasion resistance in the polymer chains while maintaining overall low styrene content, allowing different regions of the rubber material to exhibit different properties that collectively resolve the contradiction between abrasion resistance and on-ice performance.
Data Source
AI summary
A rubber composition of the present invention contains 100 parts by mass of a rubber component (A) containing 45 to 75% by mass of natural rubber and 25 to 55% by mass of a conjugated diene-based polymer, in which a bonded styrene amount of the conjugated diene compound moieties is 25% or less, 1 to 40 parts by mass of a non-modified conjugated diene-based polymer (B) which has a weight average molecular weight of 5,000 or more but less than 40,000 in terms of polystyrene as measured by GPC and in which a bonded styrene amount of the conjugated diene compound moieties is less than 10% and a bonded vinyl amount of the conjugated diene compound moieties is 20% or more, and a filler (C), in which at least one of the conjugated diene-based polymers contained in the rubber component (A) is a modified conjugated diene-based polymer. With the rubber composition, a tire having further enhanced on-ice performance and having both excellent on-ice performance and excellent abrasion resistance is obtained.