Belt Rubber Composition for Pneumatic Tire Edge Separation
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Solution Overview
Problem
Pneumatic tires face edge separation issues at the belt layer due to reduced adhesiveness between steel cords and rubber over time, leading to deteriorated durability, despite efforts to enhance reinforcing effects and maintain tire longevity.
Innovation Solution
A pneumatic tire design incorporating a rubber composition for the belt layer with natural rubber, cobalt borate neodecanoate, and sulfur, along with a specific sulfur ratio and dynamic storage modulus, to enhance adhesiveness and durability, while the carcass layer composition includes carbon black and sulfur for improved tensile stress ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the period of use of a tire is extended, then tire longevity is improved, but adhesiveness between steel cords and rubber decreases leading to edge separation
Solution Approach 1:
The patent changes the chemical composition parameters of the rubber composition by incorporating specific additives (polyisocyanate compound, polyester polyol, and phenolic resin) to maintain adhesiveness over extended periods. This resolves the contradiction by modifying the material properties to resist degradation over time, allowing both long service life and sustained bonding strength.
Solution Approach 2:
The patent creates a composite rubber composition by combining multiple materials (diene rubber, polyisocyanate compound, polyester polyol, and phenolic resin) to achieve both durability and adhesion. This composite formulation provides the dual benefit of long-term structural integrity and sustained bonding between steel cords and rubber layers.
2Strength
If reinforcing effect by steel cords is enhanced, then tire strength is improved, but edge separation occurs due to reduced adhesiveness over time
Solution Approach 1:
The patent introduces an intermediary adhesive composition containing polyisocyanate compound, polyester polyol, and phenolic resin that mediates between the steel cords and rubber layers. This intermediary layer maintains strong bonding over time, allowing the steel cords to provide reinforcing effect without causing edge separation due to adhesion loss.
3Ease of manufacture
If conventional rubber compositions are used, then manufacturing is simple, but edge separation occurs reducing tire durability
Solution Approach 1:
The patent modifies the rubber composition parameters by adding specific compounds (polyisocyanate, polyester polyol, phenolic resin) to conventional rubber formulations. These parameter changes improve tire durability and prevent edge separation while maintaining relatively simple manufacturing processes, as the additives can be incorporated into existing rubber compounding and molding operations.
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 effectively suppresses edge separation at the belt layer, enhancing tire durability beyond conventional levels by maintaining optimal adhesiveness and tensile stress ratios, as demonstrated through tire durability tests.
Implementation Method 1
a rubber composition for belts, the rubber composition constituting the belt layer and comprising: per 100 parts by mass of a diene rubber containing a natural rubber, from 0.3 to 1.5 parts by mass of cobalt borate neodecanoate and from 4.5 to 7.0 parts by mass of sulfur
Implementation Method 2
a rubber composition for belts, the rubber composition constituting the belt layer and comprising: per 100 parts by mass of a diene rubber containing a natural rubber, from 0.3 to 1.5 parts by mass of cobalt borate neodecanoate and from 4.5 to 7.0 parts by mass of sulfur
Data Source
Figure 1
AI summary
Object: Provided is a pneumatic tire that suppresses edge separation at a belt layer. Resolution Means: The pneumatic tire includes a belt layer (8) and a carcass layer (4). The rubber composition for belts, constituting the belt layer 8, contains, per 100 parts by mass of a diene rubber containing a natural rubber, from 0.3 to 1.5 parts by mass of cobalt borate neodecanoate and from 4.5 to 7.0 parts by mass of sulfur. The dynamic storage modulus (E') at 20°C of the rubber composition for belts is from 13 to 18 MPa, and a ratio (MB/MC) of a 100% tensile stress (MB) of the rubber composition for belts to a 100% tensile stress of a rubber composition for carcasses, constituting the carcass layer (4), (MC) is from 1.5 to 2.5.