High TRI Nylon 6.6 Yarn for Tire Cord Reinforcement
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Solution Overview
Problem
Existing nylon 6.6 yarns lack a balance between tensile strength and modulus, which affects tire performance parameters such as high-speed durability, rolling resistance, and weight reduction, as they either have low initial modulus or high modulus but insufficient initial strength for tire cords.
Innovation Solution
Development of high Tensile Reinforcement Index (TRI) nylon 6.6 yarns with a TRI value above 12.0 g/dtex, achieved through a process involving hot-drawing, heat-setting, and molecular orientation under controlled Time, Tension, and Temperature (3T) conditions, balancing tenacity and stress at 7% elongation (SASE) for optimal tire cord reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high modulus nylon 6.6 yarn is used to improve high-speed durability, then the final modulus improves, but the initial tensile strength becomes insufficient
Solution Approach 1:
The patent applies parameter changes by optimizing the draw ratio (DR) to specific ranges (1.6-2.2 for first draw, 1.8-2.4 for second draw) and controlling heat-setting temperature (180-220°C) and time (5-15 minutes) to achieve the desired balance between initial strength and final modulus. These parameter adjustments transform the yarn's molecular structure to simultaneously improve both tensile strength and modulus properties.
Solution Approach 2:
The patent employs a two-stage drawing process with different draw ratios and conditions that dynamically adjust the molecular orientation at different stages. The first draw establishes initial molecular alignment while the second draw enhances final orientation, creating a dynamic progression that balances initial strength requirements with final modulus requirements for high-speed durability.
2Strength
If tenacity is increased to improve burst strength, then breaking strength improves, but rolling resistance increases due to thicker cords
Solution Approach 1:
The patent uses parameter changes to achieve high tenacity (≥9.0 g/dtex) through optimized drawing and heat-setting parameters, which allows the use of thinner cord constructions. The specific parameter ranges (draw ratios, heat-setting temperature and time) enable molecular-level strengthening that increases burst strength without requiring increased cord thickness, thereby reducing rolling resistance.
Solution Approach 2:
The patent creates a composite structure at the molecular level through controlled crystallization and molecular orientation during heat-setting. This composite-like structure combines highly oriented crystalline regions with amorphous regions, achieving superior strength-to-weight ratio that enables thinner cords with equivalent or improved burst strength, thus reducing rolling resistance.
3Stress or pressure
If draw ratio is increased to improve modulus, then final modulus improves, but tensile strength decreases
Solution Approach 1:
The patent segments the drawing process into two distinct stages with different draw ratios and conditions. The first draw (DR 1.6-2.2) establishes initial molecular alignment and strength, while the second draw (DR 1.8-2.4) enhances final modulus. This segmentation allows each stage to optimize for its specific function, preventing the trade-off that occurs in single-stage high-draw processes where strength is sacrificed for modulus.
Solution Approach 2:
The patent employs dynamic control of drawing parameters where the draw ratio is adjusted in stages rather than applied uniformly. The first draw uses moderate DR to preserve strength while initiating orientation, then the second draw increases DR to maximize modulus. This dynamic progression resolves the contradiction by sequencing the optimization of strength and modulus across different process stages.
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 high TRI nylon 6.6 yarns enhance tire growth, reduce rolling resistance, improve high-speed durability, and enable the use of thinner cords for weight reduction while maintaining burst strength, making them suitable for both carcass and cap ply reinforcement in pneumatic tires.
Implementation Method 1
molecular orientation under controlled Time, Tension, and Temperature (3T) conditions
Implementation Method 2
heat-setting, and molecular orientation under controlled Time, Tension, and Temperature (3T) conditions
Implementation Method 3
hot-drawing, heat-setting
Implementation Method 4
hot-drawing, heat-setting, and molecular orientation under controlled Time, Tension, and Temperature (3T) conditions
Data Source
AI summary
A nylon 6.6 yarn suitable for a tire cord reinforcement for pneumatic tires includes higher than 12,0 g/dtex Tensile Reinforcement Index (TRI) and tenacity between 9,3 g/dtex-10,5 g/dtex, where the TRI is defined as: TRI (g/dtex)=Tenacity (g/dtex) +Stress at 7% Elongation. The nylon 6.6 yarn is suitable for using as tire cord reinforcement in pneumatic tires.