Recycled PET Tire Cord Composition for Heat-Resistant Tires
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Solution Overview
Problem
Existing tire cords made from recycled PET exhibit reduced physical properties, particularly heat resistance, due to high intrinsic viscosity and low purity, limiting their use in the tire industry and causing issues with molding processability and product quality.
Innovation Solution
A tire cord is manufactured by twisting and dipping a recycled PET yarn with specific properties, including a strength of 18.5 kgf at room temperature, 15.5 kgf at 80°C, and a heat resistance strength retention rate of 85.0% after curing, using recycled PET chips with controlled intrinsic viscosity and isophthalic acid content, and a fineness of 2,000 to 7,000 deniers, to achieve performance equivalent to virgin PET cords.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If recycled PET is used to manufacture tire cord, then environmental load is reduced, but heat resistance and physical properties deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the intrinsic viscosity of recycled PET within 0.6-2.0 dl/g and isophthalic acid content within 1.0-3.0% by mole. These parameter specifications transform the quality of recycled PET from unsuitable (high IV, low purity) to suitable (controlled IV, controlled impurity levels), enabling heat resistance of 85% or more at 80°C while maintaining environmental benefits
Solution Approach 2:
The patent applies local quality by specifying different property requirements for different aspects of the recycled PET: higher intrinsic viscosity (0.6-2.0 dl/g) for strength, controlled isophthalic acid content (1.0-3.0% by mole) for heat resistance, and specific degree of crystallinity (40-60%) for dimensional stability. This selective quality control allows the material to meet multiple performance criteria simultaneously
2Reliability
If recycled PET with high intrinsic viscosity is used, then environmental sustainability is improved, but strength and physical properties deteriorate
Solution Approach 1:
The patent resolves this contradiction by establishing an optimal parameter range for intrinsic viscosity (0.6-2.0 dl/g) that balances environmental sustainability with mechanical strength. This parameter control ensures the recycled PET maintains sufficient molecular weight for strength while being derived from recycled materials for environmental benefits
3Productivity
If recycled PET with low purity is used, then resource reuse is improved, but appearance and physical properties deteriorate
Solution Approach 1:
The patent applies local quality by selectively controlling specific impurity levels (isophthalic acid content: 1.0-3.0% by mole) while accepting other variations in recycled PET. This targeted quality control allows resource reuse of lower purity materials while ensuring the critical property (heat resistance) meets tire industry requirements
Solution Approach 2:
The patent transforms the quality of low-purity recycled PET into suitable tire cord material by controlling the isophthalic acid content parameter within 1.0-3.0% by mole. This parameter control compensates for the low purity of recycled materials, enabling product quality equivalent to or better than virgin PET
4Object-affected harmful factors
If conventional recycled PET tire cord is used, then environmental load is reduced, but heat resistance strength retention rate decreases
Solution Approach 1:
The patent resolves this contradiction by controlling the intrinsic viscosity (0.6-2.0 dl/g) and isophthalic acid content (1.0-3.0% by mole) parameters, which directly influence heat resistance. These parameter controls enable the tire cord to achieve heat resistance strength retention rate of 85% or more at 80°C, matching conventional standards while using recycled materials
Data Source
AI summary
The present invention relates to an eco-friendly tire cord and a tire using the eco-friendly tire cord, in which use of a recycled polyethylene terephthalate (PET) fiber reduces environmental load and also provides physical properties equivalent to or better than those of a tire cord that is produced by application of a virgin PET fiber and particularly, excellent heat resistance equivalent to or better than that of a tire cord produced by application of a virgin PET.