Aramid-Nylon Composite Cord Structure for Tire Rubber Adhesion
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Solution Overview
Problem
Aramid fiber composite cords exhibit poor adhesion to rubber, leading to peeling issues and reduced tire durability, especially at high speeds, due to their molecular structure.
Innovation Solution
A composite cord structure with a 2+1 twisted configuration, where two aramid fibers and one nylon fiber are twisted together, optimizing the ratio of exposed surface lengths and cross-sectional areas to enhance adhesion, with specific twist directions and twist numbers to balance adhesion and aramid fiber proportion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If aramid fibers are used as tire cord, then tire rigidity and steering stability are improved, but adhesion to rubber deteriorates
Solution Approach 1:
The patent uses a composite cord structure combining aramid fibers (for rigidity) with nylon fibers (for adhesion). The nylon component provides the necessary bonding to rubber while the aramid component maintains tire rigidity and steering stability, resolving the contradiction between strength and reliability.
2Strength
If aramid fibers are used as tire cord, then tire rigidity is improved, but durability at high speed deteriorates
Solution Approach 1:
The composite cord combines aramid fibers that provide tire rigidity with nylon fibers that prevent compression fatigue and improve adhesion. This combination resolves the contradiction by ensuring both structural strength and long-term durability under high-speed conditions.
Solution Approach 2:
The patent optimizes the local composition of the composite cord by controlling the cross-sectional area ratio of nylon fibers (S2/S0 ≤ 0.3) and the exposed surface length ratio (L2/L0 between 0.30-0.40). This ensures sufficient nylon exposure for adhesion while maintaining adequate aramid content for rigidity, achieving both high-speed durability and structural performance.
3Reliability
If nylon fiber is added to composite cord, then adhesion to rubber is improved, but proportion of aramid fiber decreases
Solution Approach 1:
The patent precisely controls the parameters of the composite cord: the cross-sectional area ratio of nylon fibers (S2/S0) is limited to 0.3 or less, and the exposed surface length ratio (L2/L0) is optimized between 0.30-0.40. These parameter constraints ensure sufficient nylon exposure for adhesion while maintaining adequate aramid fiber proportion for tire rigidity and performance.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A composite cord (10) has a 2+1 twisted structure consisting of an intermediate strand (13), formed by two first strands (11) of aramid fibers and twisted together, and one second strand (12) of nylon fibers twisted together. In a cross section perpendicular to a cord length direction, a ratio (L2/L0) of a length (L2) of an exposed surface (12s) of the second strand (12) to a length (L0) of an exposed surface (10s) of the composite cord (10) is from 0.30 to 0.40. When the upper twist of the composite cord (10) has the number of twists N20, the intermediate twist of the intermediate strand (13) has the number of twists N21, the lower twist of the second strand (12) has the number of twists N22, and the lower twist of each of the first strands (11) has the number of twists N23, N21 ≤ N20 ≤ N22 ≤ N23 is satisfied.