Heat-Expandable Rubber Composition for Winter Tire Grip
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Solution Overview
Problem
Current rubber compositions for winter tires face challenges in maintaining grip on melting ice without using studs, as existing solutions either degrade road surfaces or slow down the tire production process due to the use of high-hardness particles or blowing agents.
Innovation Solution
A heat-expandable rubber composition incorporating a diene elastomer, reinforcing filler, carbonate or hydrogen carbonate, and a hetero-cycloaliphatic acid ammonium salt, which shortens curing time while maintaining or improving grip on melting ice.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blowing agents and blowing activators are used to improve grip on melting ice, then grip performance is improved, but curing time is significantly decelerated
Solution Approach 1:
The patent changes the chemical parameters of the blowing system by selecting specific blowing agents (azodicarbonamide, 5-nitro-1,3,4-oxadiazol-2-amine-1,4-dioxide, or sodium bicarbonate) and specific activators (N-cyclohexyl-2-benzothiazyl sulphenamide or 2-mercaptobenzothiazole) with optimized concentrations. This parameter optimization allows the blowing reaction to proceed efficiently without excessively delaying the curing process, resolving the contradiction between grip improvement and curing time.
Solution Approach 2:
The patent creates a composite rubber composition combining diene elastomer, blowing agent, activator, and silica filler in specific proportions. This composite formulation synergistically balances the grip-enhancing foam structure with acceptable curing characteristics, where the combination of components compensates for the time-decelerating effect of the blowing system.
2Reliability
If high-hardness particles are incorporated to act as micro-studs on hard ice, then grip on hard ice is improved, but abrasiveness on ground surface increases
Solution Approach 1:
The patent extracts the high-hardness particles from the formulation, replacing them with a foam-based blowing system. This removal eliminates the abrasiveness problem while maintaining grip performance through the mechanical interlocking provided by the foam structure and water-soluble powders that create surface porosity and grooves.
Solution Approach 2:
The patent uses water-soluble powders (cellulose, vinyl alcohol, starch, guar gum, or xanthan gum) as temporary structural elements that dissolve during use. These disposable-like components create initial surface porosity and grooves for grip enhancement but are designed to dissolve, leaving no permanent abrasive residue on the ground surface.
3Reliability
If water-soluble powders are incorporated to create surface porosity and grooves, then grip on melting ice is improved, but the formulation complexity increases
Solution Approach 1:
The patent selects water-soluble powders that serve multiple functions: they create surface porosity for grip, form grooves for water discharge, and dissolve during use to prevent permanent abrasiveness. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in formulation complexity while achieving multiple grip-enhancing effects.
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 composition significantly reduces curing time and maintains or enhances traction on melting ice, offering a solution that balances production efficiency with grip performance.
Implementation Method 1
These blowing agents, such as for example nitro, sulphonyl or azo compounds, are capable, during a thermal activation, for example during the vulcanization of the tire, of releasing a large amount of gas, especially nitrogen, and thus of leading to the formation of bubbles within a sufficiently soft material such as a rubber composition comprising such blowing agents.
Implementation Method 2
a specific formulation based on a high content of a specific blowing agent and a specific activator combined, which makes it possible to greatly shorten curing time of the rubber composition
Implementation Method 3
during the vulcanization of the tire
Data Source
AI summary
A rubber composition usable that is heat-expandable in the unvulcanized state and expanded in the vulcanized state; in the unvulcanized state, said composition comprises a diene elastomer such as natural rubber and/or a polybutadiene, more than 50 phr of a reinforcing filler such as silica and/or carbon black, between 3 and 30 phr of a carbonate and/or a hydrogen carbonate, wherein the carbonate or the hydrogen carbonate comprises sodium or potassium, and between 3 and 60 phr of a hetero-cycloaliphatic acid ammonium salt, wherein a total content of the carbonate or the hydrogen carbonate and the hetero-cycloaliphatic acid salt is greater than 10 phr. The combined use of the carbonate and/or the hydrogen carbonate and the hetero-cycloaliphatic acid ammonium salt makes it possible to greatly shorten curing time of the rubber composition.