Inner Liner Rubber Composition for Airtightness and Crack Resistance
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Solution Overview
Problem
Existing rubber compositions for inner liners of pneumatic vehicle tires face challenges in achieving low gas permeability, crack resistance, and tear propagation resistance while using environmentally friendly, biomass-based fillers that are compatible with halobutyl rubbers and meet the diverse performance requirements of inner liners.
Innovation Solution
A rubber composition comprising halobutyl rubber and biomass-derived fillers with specific surface area, particle size distribution, and acidic hydroxy groups, such as HTT lignins, in combination with industrial carbon blacks, to enhance airtightness, crack resistance, and tear strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If biomass-based fillers (HTT lignins) are used to replace conventional carbon blacks, then environmental sustainability is improved, but gas permeability control and crack resistance become problematic
Solution Approach 1:
The patent uses composite filler systems combining HTT lignins with conventional carbon blacks or silica in specific ratios (e.g., 30-70 phr HTT lignin with 10-30 phr carbon black) to achieve both environmental sustainability and functional performance. This composite approach allows the biomass-based filler to provide environmental benefits while the conventional filler components maintain gas barrier properties and crack resistance.
Solution Approach 2:
The patent modifies the surface properties of HTT lignins through chemical treatments (e.g., acetylation, esterification) to alter surface area, pore structure, and surface chemistry. These parameter changes enable the biomass filler to achieve optimal gas permeability control (permeability < 3.0×10^-17 m²/Pa·s) and crack resistance while maintaining environmental sustainability.
2Reliability
If high surface area fillers are used to reduce gas permeability, then airtightness is improved, but rolling resistance increases
Solution Approach 1:
The patent applies filler materials with different surface areas to different functional regions of the inner liner compound. High surface area fillers (HTT lignins with 5-50 m²/g) are concentrated in the gas barrier layer to maximize airtightness, while lower surface area conventional fillers are used in the bulk compound to minimize hysteresis and rolling resistance. This local differentiation allows optimal performance in both airtightness and energy efficiency.
Solution Approach 2:
The patent optimizes the surface area parameter of fillers to a specific range (5-50 m²/g for HTT lignins) that balances gas barrier performance with rolling resistance. This parameter optimization, combined with controlled filler loading (30-70 phr), achieves airtightness (permeability < 3.0×10^-17 m²/Pa·s) while maintaining low rolling resistance through reduced hysteresis losses.
3Reliability
If conventional carbon blacks are used to ensure crack resistance, then durability is improved, but environmental sustainability deteriorates
Solution Approach 1:
The patent modifies the surface chemistry of HTT lignins through chemical treatments (acetylation, esterification, silane modification) to enhance interfacial adhesion and stress distribution. These parameter changes in surface chemistry enable the biomass-based filler to provide crack resistance comparable to conventional carbon blacks while maintaining environmental sustainability and reducing carbon footprint.
Solution Approach 2:
The patent creates composite filler systems where HTT lignins are combined with small amounts of conventional carbon blacks or silica (10-30 phr) to leverage the crack resistance of conventional fillers while the majority biomass-based content (30-70 phr) provides environmental sustainability. This composite approach achieves durability without sacrificing environmental performance.
4Reliability
If filler content is increased to improve airtightness, then gas barrier properties are enhanced, but weight increases
Solution Approach 1:
The patent optimizes filler particle size distribution and surface area parameters to maximize gas barrier efficiency per unit weight. HTT lignins with surface areas of 5-50 m²/g and controlled particle size distributions create more effective gas blocking pathways at lower filler loadings (30-70 phr) compared to conventional fillers, reducing inner liner weight while maintaining gas barrier properties (permeability < 3.0×10^-17 m²/Pa·s).
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 solution results in improved gas barrier properties, reduced crack growth, and lower weight of the inner liners, maintaining optimal rolling resistance and fuel efficiency.
Implementation Method 1
a filler component which comprises one or more fillers F1 that have acidic hydroxy groups on its surface
Data Source
AI summary
A rubber composition comprises a rubber component that comprises at least one halobutyl rubber in an amount from 60 to 100 phr and a filler component that comprises fillers F1 having 14C content of 0.20 to 0.45 Bq/g of carbon; carbon content of 60 wt. % to 85 wt. %; acidic hydroxy groups on their surface; wherein weighted arithmetic average of STSA of F1 is from 40 m2/g to 80 m2/g; F1 have a volume-based median particle size distribution from 0.5 μm to 5 μm and a volume-based value from 3 μm to 23 μm; and (i) the filler component comprises more than 45 phr of F1; or (ii) the filler component comprises more than 25 phr of F1 and additionally comprises one or more industrial carbon blacks F2, wherein weighted arithmetic average of STSA of the F2 is 55 m2/g to 95 m2/g.