Pneumatic Radial Tire Polyester Cord Adhesion
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Solution Overview
Problem
Run-flat tires face challenges with the separation of polyester fibers from rubber due to poor heat-resistant adhesive properties, leading to reduced durability and increased vibration during high-speed travel.
Innovation Solution
A pneumatic radial tire design incorporating a polyester cord with specific physical properties and pre-treatment using an epoxy compound, ensuring a high adhesion level and balanced strength and fatigue resistance, is developed. The polyester cord is spirally wound with an angle of 0° to 5° and treated with a specific adhesive agent composition to enhance adhesion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyester fiber is used as a belt reinforcing layer, then cost is reduced and flexibility is improved, but heat resistant adhesive property with rubber deteriorates, causing separation between fiber and rubber
Solution Approach 1:
An adhesive agent is introduced as an intermediary substance between the polyester fiber and rubber to improve adhesion. The adhesive agent contains specific chemical components that bond effectively with both the polyester fiber surface and the rubber, preventing separation under heat and mechanical stress while maintaining the cost advantage of using polyester instead of aramid.
Solution Approach 2:
The chemical composition and physical properties of the adhesive agent are optimized to achieve maximum bonding strength at operating temperatures. By adjusting parameters such as adhesive chemistry, application method, and curing conditions, the system achieves reliable adhesion between polyester and rubber without requiring expensive aramid materials.
2Reliability
If aramid fiber is used as a belt reinforcing layer, then heat resistant adhesive property with rubber is improved, but material cost increases significantly
Solution Approach 1:
The invention replaces expensive aramid fiber with a more economical polyester fiber combined with an adhesive agent system. This substitution achieves comparable or sufficient adhesion performance at lower material cost, making the tire more economically viable while maintaining run-flat capabilities and heat resistance.
Solution Approach 2:
The system creates a composite structure combining polyester fiber with a specially formulated adhesive agent. This composite approach leverages the cost advantage of polyester while the adhesive component provides the bonding performance previously only achievable with expensive aramid, resulting in a cost-effective alternative material system.
3Reliability
If polyester cord with high adhesion is used, then run-flat durability is improved, but vibration during rolling and tire protrusion during high-speed traveling may increase if adhesion is too strong
Solution Approach 1:
The adhesive properties are precisely tuned to achieve optimal bonding strength. The adhesive agent formulation and application parameters are controlled to provide sufficient adhesion for run-flat durability while preventing excessive rigidity that would cause vibration and protrusion. This balanced parameter optimization resolves the contradiction between durability and ride comfort.
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 improves run-flat durability, reduces vibration, and inhibits tire protrusion during high-speed travel by ensuring strong adhesion between the polyester cord and rubber, maintaining excellent adhesion performance even under high heat and dynamic strain.
Implementation Method 1
the polyester cord is pre-treated using an epoxy compound prior to an adhesive agent treatment and the adhesion level of the polyester cord in a residual adhesion evaluation method after an adhesive agent treatment is 5 N/cord or higher
Data Source
Figure 1~3
Figure 4~5
AI summary
Provided is a pneumatic radial tire in which run-flat durability can be improved while inhibiting vibration during tire rolling and tire protrusion during high-speed traveling. A pneumatic radial tire comprising a side reinforcing rubber layer 5 having a crescent shaped cross-section arranged on the inside of a carcass 4 at a side wall portion 2, and a belt reinforcing layer 9 which is formed by spirally winding a strip which is formed by covering a polyester cord with rubber with respect to the tire circumferential direction. The polyester cord taken out from pneumatic radial tire satisfies that the ply twist coefficient α1 and the cable twist coefficient α2 represented by the following formulae: α1=N1×0.125×D1/ρ0.5×10-3 α2=N2×0.125×D2/ρ0.5×10-3 are 0.1 to 0.4 and 0.1 to 0.45, respectively, and the initial tensile resistance degree is 7 to 20 GPa, and the adhesion level of the polyester cord in a residual adhesion evaluation method after an adhesive agent treatment is 5 N/cord or higher.