Cord for rubber reinforcement, method for producing same, and rubber product

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Solution Overview

Problem

Conventional rubber-reinforcing cords with aramid fibers fail to withstand high loads and suffer from fraying, fracture, or elongation, leading to breakage in rubber products like vehicle accessory belts, particularly in Integrated Starter Generator hybrid systems.

Innovation Solution

A rubber-reinforcing cord is developed with aramid fibers, featuring a specific twisting process and coating composition that includes a resorcinol resin, phenolic compound-formaldehyde condensate, and rubber component, applied in a manner that enhances adhesion and resistance to fraying, with primary and final twisting rates optimized for high tensile strength and anti-elongation properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional rubber-reinforcing cords with aramid fibers are used, then the basic reinforcement function is provided, but the cords cannot withstand high loads and suffer from fraying, fracture, or elongation

Engineering Contradiction:
Improvetensile strengthVSAvoidresistance to fraying and fracture
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent applies composite materials by combining aramid fibers with a specifically formulated coating containing phenolic resin, rubber component, and filler. This composite structure allows the cord to achieve both high tensile strength from the aramid fibers and improved reliability through the coating that prevents fraying and fracture. The coating acts as a protective matrix that binds the fibers together and to the rubber product.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent employs parameter changes by optimizing the composition ratios of the coating components (phenolic resin, rubber component, filler) and controlling the twisting parameters (twist density, twist direction). These parameter adjustments enhance the cord's ability to withstand high loads while maintaining resistance to fraying and fracture, resolving the contradiction between strength and reliability.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If the reinforcing cord is exposed on the edge surface of the rubber product, then the production process is simplified, but the exposed portion undergoes fraying leading to protrusion of fibers

Engineering Contradiction:
Improveproduction process simplicityVSAvoidfraying of exposed fibers
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical-chemical parameters of the fiber surface by applying a coating formulation containing phenolic resin and rubber component. This coating modifies the surface properties of the aramid fibers, providing a protective layer that prevents fraying of exposed portions while maintaining the simplicity of the production process. The coating acts as a barrier that secures the fibers against mechanical damage.

Inventive Principle:
Principle #35Parameter changes

3Power

If the rubber product is subjected to higher loads in Integrated Starter Generator hybrid systems, then the power and functionality are enhanced, but the conventional cords suffer from breakage

Engineering Contradiction:
Improveload capacityVSAvoiddurability under high load
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent uses composite materials to enable the rubber product to withstand higher loads in Integrated Starter Generator hybrid systems. The combination of high-strength aramid fibers with a specially designed coating system creates a reinforcement structure that maintains durability under elevated load conditions. The coating distributes the mechanical stress across the fiber bundle, preventing localized failure.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies beforehand cushioning by incorporating a protective coating on the aramid fibers before the rubber product is put into service. This pre-applied coating acts as a cushioning layer that protects the fibers from sudden shocks and high loads, preventing breakage and maintaining reliability in demanding applications such as ISG hybrid systems.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 provides a rubber-reinforcing cord with excellent anti-fraying, high tensile strength, and anti-elongation properties, resulting in a rubber product with enhanced durability and resistance to bending fatigue.

Implementation Method 1

a first coating formed by applying a treatment agent including a resorcinol resin and a phenolic compound-formaldehyde condensate

Methodology Applied
Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 2

giving each of the strands primary twists at a primary twisting rate of 50 to 100 twists/m; assembling the at least three strands each given primary twists; and giving the at least three strands final twists at a final twisting rate of 120 to 200 twists/m

Methodology Applied
Scientific EffectMechanical orientation:

Data Source

PatentEP3770309B1Cord for rubber reinforcement, method for producing same, and rubber product
Publication Date: 2023.08.09 NIPPON SHEET GLASS CO LTD
  • EP3770309B1 patent drawingFigure 1

AI summary

A rubber-reinforcing cord (12) of the present invention includes at least three strands. Each of the strands includes at least one filament bundle and a first coating provided to cover at least a portion of the surface of the filament bundle. The filament bundle consists essentially of aramid fiber filaments. The mass of the first coating is in the range of 14 to 25% with respect to the mass of the filament bundle. Each of the strands is given primary twists at a primary twisting rate of 50 to 100 twists/m. The at least three strands each given primary twists are assembled and given final twists at a final twisting rate of 120 to 200 twists/m.