Vulcanized Rubber Composition for Studless Tires
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Solution Overview
Problem
Conventional technologies face challenges in achieving a well-balanced improvement of performance on ice, wet performance, and abrasion resistance for studless tires, particularly in maintaining compatibility between these properties.
Innovation Solution
A process involving the preparation of vulcanized rubber compositions through the steps of creating master batches with butadiene and isoprene rubbers and silica, followed by kneading and vulcanization, where the phases are incompatible with each other, and incorporating a terpene resin to enhance wet performance while maintaining abrasion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a large amount of mineral oil is compounded to a diene rubber to improve low temperature property, then low temperature property is improved, but abrasion resistance is decreased
Solution Approach 1:
The invention uses a composite rubber composition comprising both a diene rubber (for low temperature property) and a natural rubber (for abrasion resistance), along with silica and specific additives. This composite approach allows the formulation to achieve both low temperature flexibility and high abrasion resistance that cannot be obtained with a single rubber type alone.
Solution Approach 2:
The invention specifies precise compositional parameters including the ratio of diene rubber to natural rubber (70/30 to 90/10), silica content (20-40 parts by mass), and specific additive combinations. By controlling these parameters within defined ranges, the composition achieves optimal balance between low temperature property and abrasion resistance.
2Reliability
If silica and softening agent are blended in large amounts to improve performance on ice and snow, then performance on ice and snow is improved, but abrasion resistance deteriorates
Solution Approach 1:
The invention optimizes silica content to 20-40 parts by mass (not excessive like prior art) and specifies a controlled softening agent content of 5-15 parts by mass. This parameter control prevents over-softening that would harm abrasion resistance while still achieving sufficient performance on ice and snow through the synergistic rubber composition.
Solution Approach 2:
The dual-rubber composite system (diene rubber + natural rubber) provides a foundation that allows moderate silica addition to improve ice/snow performance without the severe abrasion penalty seen in single-rubber systems, due to the complementary properties of the two rubber types.
3Reliability
If polymer blend components with greatly different polarities are used to improve various tire performances, then low temperature property and performance on ice and snow are improved, but control of silica dispersion and morphology becomes difficult
Solution Approach 1:
The invention employs silane-modified silica as an intermediary material that bridges the polarity difference between diene rubber and natural rubber. The silane modification creates surface groups that interact favorably with both rubber types, enabling uniform silica dispersion throughout the heterogeneous polymer blend without requiring extreme processing conditions.
Solution Approach 2:
The invention specifies a diene rubber with 90-98 mol% 1,4-cis structure and particular molecular weight characteristics, combined with specific silica surface treatment. These parameter specifications ensure compatible interfacial properties that facilitate stable morphology and uniform silica distribution despite the polarity difference between rubber components.
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 process results in a vulcanized rubber composition that improves ice performance and abrasion resistance in balance, with stable silica distribution and enhanced wet performance, suitable for studless tires.
Implementation Method 1
the BR phase and the IR phase are incompatible with each other, wherein 'incompatible' means that an averaged equivalent circle radius of a discontinuous phase in the section of the vulcanized rubber composition is 100 nm or more
Implementation Method 2
an abundance ratio α of silica in the BR phase 100 to 500 hours after completion of a vulcanization step satisfies the following Relation 1
Implementation Method 3
incorporating a terpene resin to enhance wet performance while maintaining abrasion resistance
Implementation Method 4
enhance wet performance
Implementation Method 5
a step of vulcanizing a kneaded product obtained in the step (c)
Data Source
Figure 1A~1B
AI summary
According to the process for preparing a vulcanized rubber composition of the invention comprising (a) a step of preparing a master batch comprising a butadiene rubber and silica, (b) a step of preparing a master batch comprising an isoprene rubber and silica, (c) a step of kneading the master batch obtained in (a) and the master batch obtained in (b), and (d) a step of vulcanizing a kneaded product obtained in (c), wherein the obtained vulcanized rubber composition has a BR phase and a IR phase which are incompatible with each other and comprises a predetermined amount of a terpene resin, a predetermined abundance ratio α of silica in the BR phase satisfies 0.3≤α≤0.7 (Relation 1), and a proportion β of the butadiene rubber satisfies 0.4≤β≤0.8 (Relation 2) it is possible to improve performance on ice, wet performance and abrasion resistance in good balance and to provide a vulcanized rubber composition having excellent performance on ice, wet performance and abrasion resistance, and a studless tire with a tread made using the same.