Pneumatic Tire Cap Tread and Conducting Rubber Composition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-performance tires face challenges in achieving durability against rubber fracture while maintaining good conducting properties and fuel economy, especially when using silica formulations that can impair conducting properties and cause heat build-up during high-speed cornering.
Innovation Solution
A pneumatic tire design featuring a cap tread with a rubber composition containing 60-110 parts of silica and 0.5-3.0 parts of sulfur, and a conducting rubber with 50-85 parts of fine particle carbon black and 1.8-3.0 parts of sulfur, ensuring a hardness difference of no more than 2.0 from the cap tread, which enhances durability and extrusion processability while maintaining good conducting properties and fuel economy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a large amount of silica is incorporated into high hardness tread rubbers to reduce heat build-up and improve fuel economy, then low heat build-up properties and fuel economy are improved, but the conducting properties of the tire are impaired and processability in kneading or extrusion becomes difficult
Solution Approach 1:
The tire structure is segmented into distinct functional zones: a cap tread layer containing silica for low heat build-up, and conducting rubber layers containing carbon black for electrical conductivity. This segmentation allows each layer to optimize its specific function without compromising the other, resolving the contradiction between heat reduction and conducting properties
Solution Approach 2:
Different regions of the tire are assigned different material compositions tailored to their specific functions. The cap tread uses silica-rich composition for heat management, while the conducting rubber layers use carbon black-rich composition for electrical conductivity. This local differentiation enables simultaneous achievement of low heat build-up and good conducting properties
2Reliability
If a conducting rubber layer is placed in the tread to maintain conducting properties, then conducting properties are improved, but the risk of fracture phenomena in the tread rubber increases
Solution Approach 1:
The hardness of both the cap tread and conducting rubber is precisely controlled within specific ranges (cap tread: 65-75, conducting rubber: 63-73). This parameter optimization ensures that the conducting rubber is soft enough to prevent fracture while maintaining sufficient structural integrity, resolving the contradiction between conducting properties and fracture resistance
3Shape
If conducting rubber is processed through a narrow extrusion orifice to form elongated shapes, then the conducting rubber structure is formed, but extrusion processability becomes difficult
Solution Approach 1:
The Mooney viscosity of the unvulcanized conducting rubber is controlled within the range of 40-70, and the hardness of the vulcanized product is maintained at 63-73. These parameter specifications ensure the rubber has appropriate flow characteristics for extrusion through narrow orifices while maintaining structural integrity, resolving the contradiction between shape formation and processability
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 tire achieves a balance between cap tread durability, conducting rubber extrusion processability, and fuel economy by suppressing heat build-up, preventing fracture phenomena like blowout and chipping, and ensuring excellent conducting properties and low electrical resistance.
Implementation Method 1
silica formulations to simultaneously obtain excellent low heat build-up properties (fuel economy)
Implementation Method 2
a fine particle carbon black having a nitrogen adsorption specific surface area of 105 m2/g or more
Implementation Method 3
the rubber composition for cap treads that contains, per 100 parts by mass of a rubber component, 60 to 110 parts by mass of silica and 0.5 to 3.0 parts by mass of sulfur
Data Source
Figure 1
AI summary
Provided is a pneumatic tire simultaneously achieving a cap tread with durability against rubber fracture and a conducting rubber with extrusion process passability (extrusion processability) while ensuring good conducting properties and good fuel economy. The pneumatic tire includes: a cap tread; and a conducting rubber disposed to be exposed on the surface of the tread, the cap tread being formed of a rubber composition for cap treads that contains predetermined amounts of specific components and has, when vulcanized, predetermined hardness and tan δ, the conducting rubber being formed of a rubber composition for conducting rubbers that contains predetermined amounts of specific components and has, when vulcanized, a predetermined hardness which has a difference from the vulcanized rubber composition for cap treads of at most a predetermined value.