Innerliner Rubber Composition for Low Rolling Resistance
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Solution Overview
Problem
Conventional tire innerliners face challenges in balancing air retention with reduced rolling resistance, often resulting in stiff innerliners that compromise tire performance.
Innovation Solution
A rubber composition for the innerliner is developed, comprising at least 60 phr of butyl rubber, up to 40 phr of diene-based rubber, 35 to 70 phr of reinforcing filler such as calcium carbonate and carbon black, and a curing system including zinc oxide and a sulfur-based curing agent, which together enhance air retention while reducing stiffness and rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional innerliner compositions use high proportions of butyl rubber and traditional additives to improve air retention, then air retention performance is improved, but the innerliner becomes relatively stiff and rolling resistance increases
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating specific diene-based rubbers (polyisoprene, polybutadiene, or styrene-butadiene rubber) in controlled proportions (5-40 parts by weight per 100 parts butyl rubber) and using precise filler ratios (calcium carbonate to carbon black ratio of 2:1 to 10:1). This parameter optimization maintains air retention while reducing stiffness and rolling resistance through balanced compositional design.
Solution Approach 2:
The patent creates a composite innerliner material combining butyl rubber (60-100 parts by weight) with diene-based rubber (5-40 parts by weight), calcium carbonate filler (20-60 parts by weight), and carbon black filler (2-20 parts by weight). This composite structure integrates the air-retention properties of butyl rubber with the flexibility-enhancing properties of diene-based rubber and the reinforcing properties of mineral fillers, achieving both low rolling resistance and satisfactory air retention.
2Reliability
If reinforcing fillers are increased to improve mechanical strength and air retention, then air retention is improved, but the innerliner stiffness increases and rolling resistance worsens
Solution Approach 1:
The patent applies local quality by using two different types of fillers with distinct functions: calcium carbonate provides bulk reinforcement and air retention (20-60 parts by weight), while carbon black provides structural strength and flexibility (2-20 parts by weight). The specific ratio range (2:1 to 10:1) optimizes the local properties of each filler type to achieve both air retention and acceptable stiffness levels without excessive rolling resistance.
Solution Approach 2:
The patent uses a composite filler system combining calcium carbonate and carbon black in specific proportions, integrated with butyl rubber and diene-based rubber. This multi-component composite approach balances the reinforcing effects (improving air retention) with the flexibility benefits of diene-based rubber, achieving a compromise between strength and rolling resistance that conventional single-material systems cannot accomplish.
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 proposed rubber composition achieves improved air retention and lower rolling resistance, with a strain-controlled loss modulus indicating reduced rolling resistance without compromising air permeability performance.
Implementation Method 1
a curing system including zinc oxide and a sulfur-based curing agent
Implementation Method 2
designed to prevent or retard the permeation of air and moisture into the carcass from the tire's inner air chamber
Data Source
AI summary
A rubber composition for an innerliner (30) is disclosed. The rubber composition comprises 100 phr of elastomers, comprising at least 60 phr of a butyl rubber and 0 to 40 phr of a diene-based rubber; 35 to 70 phr of a reinforcing filler; and a curing system for curing the elastomers. Also, an innerliner (30) is disclosed composed of or formed from: 25 to 35 phr of natural rubber; 65 to 75 phr of a halobutyl rubber; 45 to 60 phr of calcium carbonate; 2 to 12 phr of carbon black; optionally, at least one of an oil, a plasticizer, and a tackifier resin; a sulfur based curing agent; at least 1 phr of zinc oxide; and a cure accelerator.