Silica-Filled Rubber Sidewall for Low Rolling Resistance
Solution Overview
Problem
Existing tire sidewall materials with low rolling resistance tend to have increased electrical resistance, making it difficult to dissipate electrostatic charges effectively, and there is a need for a sulfur-crosslinkable rubber mixture that reduces hysteresis and rolling resistance while maintaining efficient charge dissipation.
Innovation Solution
A sulfur-crosslinkable rubber mixture comprising 20 to 80 phr of natural rubber and/or synthetic polyisoprene, 20 to 80 phr of polybutadiene functionalized for attachment to silica, and 20 to 50 phr of silica with specific surface area characteristics, along with mercaptosilanes, to achieve reduced hysteresis and rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If silica filler is used instead of carbon black to reduce rolling resistance, then hysteresis and rolling resistance are reduced, but electrical resistance increases making charge dissipation difficult
Solution Approach 1:
The patent uses a composite filler system combining silica (for low rolling resistance) with conductive carbon black (for charge dissipation). The silica provides the low hysteresis needed for reduced rolling resistance, while the carbon black forms conductive pathways to maintain electrical conductivity and enable electrostatic charge dissipation, thus resolving the contradiction between energy loss reduction and reliability maintenance
Solution Approach 2:
The patent applies different filler types in different functional zones: silica as the primary filler for low rolling resistance performance, supplemented with conductive carbon black specifically to address electrical conductivity requirements in critical areas, creating local quality variations that satisfy both low energy loss and reliable charge dissipation
2Reliability
If carbon black is used in sidewalls to ensure charge dissipation, then electrical conductivity is maintained, but rolling resistance increases due to high hysteresis
Solution Approach 1:
The patent creates a composite filler system where silica (20-80 phr) provides low rolling resistance through low hysteresis, while conductive carbon black (1-20 phr) is added specifically to maintain electrical conductivity for charge dissipation, thus combining the benefits of both fillers while mitigating their individual drawbacks
Solution Approach 2:
The patent optimizes the proportion of carbon black to a specific range (1-20 phr) - significantly lower than traditional formulations - while compensating with silica filler. This parameter change maintains sufficient electrical conductivity for charge dissipation while minimizing the hysteresis contribution from carbon black, thereby reducing rolling resistance
3Loss of energy
If low activity fillers or small amounts of active filler are used to reduce rolling resistance, then hysteresis is reduced, but electrical resistance increases
Solution Approach 1:
The patent combines low activity silica filler (for low hysteresis and low rolling resistance) with conductive carbon black filler (for electrical conductivity). The silica reduces energy loss through low hysteresis, while the carbon black network maintains electrical pathways for charge dissipation, thus achieving both low hysteresis and maintained electrical conductivity
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 rubber mixture significantly reduces hysteresis and rolling resistance when used in tire sidewalls, while maintaining effective electrostatic charge dissipation, as demonstrated by improved rebound resilience and reduced loss factor values.
Implementation Method 1
polybutadiene functionalized for attachment to silica
Implementation Method 2
sulfur-crosslinkable rubber mixture
Implementation Method 3
reduced hysteresis, which leads to reduced rolling resistance
Data Source
AI summary
The invention relates to a sulfur-crosslinkable rubber mixture, especially for the sidewall of pneumatic vehicle tires, and to a pneumatic vehicle tire whose sidewall consists at least partly of the sulfur-crosslinked rubber mixture. For reduced hysteresis, hence leading to low rolling resistance when used as a sidewall mixture, the rubber mixture comprises20 to 80 phr of natural rubber and/or synthetic polyisoprene,20 to 80 phr of at least one polybutadiene functionalized for attachment to silica and20 to 50 phr of at least one silica with a CTAB surface area (to ASTM D 3765) of 50 to 130 m2/g and a nitrogen surface area (BET surface area) (to DIN ISO 9277 and DIN 66132) of 60 to 140 m2/g.