PET Tire Cord Crystallinity for Dimensional Stability
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Solution Overview
Problem
Current tire cords made from nylon or polyester-based materials suffer from low dimensional stability, leading to tire shape deformation and reduced riding comfort due to temperature and load changes during driving and parking, especially at high speeds.
Innovation Solution
A PET tire cord with a Flat Spot Index (FSI) of 5.0% or less is developed, achieved through controlled melt-spinning to create undrawn PET fibers with high crystallinity and low amorphous orientation factor, which are then drawn and twisted to form a dipped cord with specific properties, ensuring minimal deformation and superior dimensional stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If nylon or polyester-based materials are used for tire cords, then cost and processing ease are improved, but dimensional stability deteriorates leading to tire shape deformation
Solution Approach 1:
The patent changes the material parameter from conventional nylon/polyester to PET (polyester) fiber with specific crystallinity characteristics. By controlling the crystallinity of PET fibers through controlled melting and spinning processes, the material achieves both ease of manufacture and superior dimensional stability, resolving the contradiction between manufacturing ease and dimensional stability.
2Device complexity
If conventional tire cords are used, then manufacturing simplicity is maintained, but tire shape deformation occurs due to temperature and load changes
Solution Approach 1:
The patent modifies the physical parameters of the tire cord material by using PET fiber with controlled crystallinity (30-70%). This parameter change enables the cord to maintain tire shape under temperature and load variations while keeping the manufacturing process relatively simple, thus resolving the contradiction between device complexity and tire shape maintenance.
3Speed
If high-speed driving is required, then performance and durability are improved, but dimensional stability of tire cords deteriorates
Solution Approach 1:
The patent changes the material parameters to PET fiber with specific crystallinity characteristics, which provides superior dimensional stability even at high speeds. The controlled crystallinity structure maintains shape and prevents deformation during high-speed driving conditions, resolving the contradiction between speed and dimensional stability.
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 PET tire cord maintains uniform tire shape and improves riding comfort by preventing clattering and ensuring stable high-speed performance, outperforming conventional materials in terms of dimensional stability and durability.
Implementation Method 1
controlled melt-spinning to create undrawn PET fibers with high crystallinity
Data Source
AI summary
Disclosed is a PET tire cord which has a flat spot index (FSI) defined by the following Calculation Formula 1 of 5.0% or less:Flat Spot Index (FSI)(%)=(L1−L2)/L0×100 Calculation Formula 1wherein, L0 is an initial length of the tire cord, L1 is a length of the tire cord that is measured after providing a load corresponding to 13% of the strength at break of the cord for 5 minutes at 120° C. and cooling the same to 24° C. while maintaining the load, and L2 is a length of the tire cord that is measured after providing a load corresponding to 13% of the strength at break of the cord for 5 minutes at 120° C. and cooling the same to 24° C. while remaining the load of 0.01 g/d only.