Polybutadiene Rubber Composition for Pneumatic Tire Processability
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Solution Overview
Problem
Current pneumatic tire rubber compositions face challenges in achieving a balance between processability and properties such as fuel efficiency, durability, breaking resistance, and abrasion resistance, with existing solutions either compromising on strength or deteriorating abrasion resistance when reducing filler content to improve fuel efficiency.
Innovation Solution
A rubber composition for pneumatic tires comprising a polybutadiene with specific Mooney viscosity, stress relaxation time, molecular weight distribution, and cis-structure, combined with styrene-butadiene rubber and silica, optimized to enhance processability and tire properties, including fuel efficiency and abrasion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the content of fillers such as carbon black and silica is reduced to improve fuel efficiency, then fuel efficiency is improved, but the strength and abrasion resistance of the rubber composition decrease
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molecular weight distribution (Mw/Mn ratio of 2.0-4.0) and microstructure (cis-structure content of 90-98 mol%) of polybutadiene. These parameter optimizations enable the rubber composition to achieve both reduced filler content for improved fuel efficiency and maintained strength through enhanced polymer chain entanglement and interaction
Solution Approach 2:
The patent uses composite materials by combining polybutadiene with specific another rubber (natural rubber, SBR, or NR) in optimized ratios. This composite approach allows the synergistic interaction between different rubber types to compensate for reduced filler content, maintaining strength and abrasion resistance while improving fuel efficiency
2Use of energy by moving object
If polybutadiene is used to improve fuel efficiency, then fuel efficiency is improved, but processability deteriorates
Solution Approach 1:
The patent resolves this contradiction through parameter changes by controlling the Mooney viscosity (ML 1+4 at 100°C) within 40-80 and the ratio of 5% toluene solution viscosity to Mooney viscosity (Tcp/ML) within 0.8-1.8. These parameter optimizations balance the fuel efficiency benefits of polybutadiene with adequate processability during tire manufacturing
Solution Approach 2:
The patent applies dynamics by optimizing the stress relaxation time (T80) of the polybutadiene within 5.0-50.0 seconds. This dynamic parameter control allows the rubber to exhibit appropriate flow characteristics during processing while maintaining the desired fuel efficiency properties in the final product
3Weight of moving object
If the amount of rubbers in sidewalls is reduced to lighten tires, then tire weight is reduced, but durability such as tensile strength, tensile elongation, tear strength and flex crack growth resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the molecular weight distribution and cis-structure content of polybutadiene, which enhances the intrinsic strength and elasticity of the rubber matrix. This allows reduced rubber content to maintain adequate durability through improved polymer network structure
Solution Approach 2:
The patent uses composite materials by combining polybutadiene with another rubber (natural rubber, SBR, or NR) in optimized ratios. This composite structure provides synergistic effects that maintain tensile strength, tear strength, and flex crack growth resistance even when total rubber content is reduced for lighter tires
Data Source
AI summary
A pneumatic tire having a tire component prepared by use of a rubber composition according to the present invention which comprises: a polybitadiene (i) which satisfies conditions of (A) a Mooney viscosity (ML1+4, 100°C) of 43 to 70, (B) a ratio (Tcp/ML1+4, 100°C) of 5% by mass toluene solution viscosity (Tcp) to Mooney viscosity (ML1+4, 100°C) of 0.9 to 1.7, (C) a stress relaxation time (T80), being a time until a torque is attenuated by 80% assuming that the torque at the end of ML1+4, 100°Cmeasurement is 100%, of 10.0 to 40.0 seconds, (D) a molecular weight distribution (Mw/Mn) of 2.50 to 4.00, and (F) a proportion of cis-structure in microstructural analysis of not more than 98 mol%; another rubber (ii); and a rubber reinforcing material (iii), is excellent in processability and properties of tire.