Elastomer Reinforcement Cord Filling for Rust Resistance and Adhesion

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Solution Overview

Problem

Existing reinforcement cords for elastomers, such as steel cords, face issues with rust formation due to moisture ingress, leading to reduced adhesion strength between rubber and steel filaments, and inadequate corrosion fatigue resistance.

Innovation Solution

A cord configuration with a specific ratio of polymeric material filling the gaps between metallic filaments, optimized void connectivity, and use of maleic acid-modified polyethylene resin filaments, ensuring adequate adhesion and rust prevention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If resin filaments are used to fill gaps between steel filaments to prevent rust, then corrosion resistance is improved, but adhesion strength between rubber and steel filaments deteriorates due to interface formation

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidadhesion strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention changes the physical and chemical parameters of the polymeric material, specifically selecting materials with melting points of 80°C to 160°C and controlling the filling ratio to 52-120% of the gap region. This optimization ensures the resin fills gaps effectively to prevent rust while minimizing interface formation that would reduce adhesion strength between rubber and steel filaments.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses composite materials by combining steel filaments with specific polymeric materials (such as maleic acid-modified polyethylene, polypropylene, or ionomers) in a controlled configuration. The composite structure allows the polymeric material to fill gaps and prevent corrosion while maintaining optimal adhesion properties through careful selection of material composition and filling ratio.

Inventive Principle:
Principle #40Composite materials

2Reliability

If excessive polymeric material is used to fill gaps, then rust prevention is improved, but adhesion strength deteriorates and resin exposure occurs during tensile testing

Engineering Contradiction:
Improverust preventionVSAvoidadhesion strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention precisely controls the filling ratio parameter of the polymeric material to be 52-120% of the gap region between steel filaments. This quantitative control prevents both insufficient rust protection and excessive resin exposure, optimizing the balance between corrosion resistance and adhesion strength while avoiding resin exposure during tensile testing.

Inventive Principle:
Principle #35Parameter changes

3Strength

If insufficient polymeric material is used to fill gaps, then adhesion strength is maintained, but voids are insufficiently filled and corrosion fatigue resistance deteriorates

Engineering Contradiction:
Improveadhesion strengthVSAvoidcorrosion fatigue resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention sets the minimum filling ratio at 52% of the gap region to ensure adequate void filling for corrosion protection. This threshold ensures sufficient rust prevention and corrosion fatigue resistance while maintaining acceptable adhesion strength, preventing the deterioration of reliability that would occur with insufficient polymeric material.

Inventive Principle:
Principle #35Parameter changes

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 enhanced adhesion strength and corrosion resistance, preventing rust development and maintaining durability of the elastomer-reinforcing cord.

Implementation Method 1

the resin filament is melted during vulcanization to cause rubber to penetrate into the steel filaments

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

during vulcanization, the rubber flows into a region where the resin filaments are present, creating an interface through which a polymeric material derived from the resin filaments and the rubber are in contact with each other

Methodology Applied
Scientific EffectFlow:

Data Source

PatentEP3617398B1Cord for reinforcing elastomers
Publication Date: 2025.06.25 BRIDGESTONE CORP
  • EP3617398B1 patent drawingFigure 1~2
  • EP3617398B1 patent drawingFigure 3~5
  • EP3617398B1 patent drawingFigure 6~8

AI summary

A cord for reinforcing elastomers excellent in adhesion to elastomers such as rubber is provided. The cord is a cord for reinforcing elastomers (10) that includes metallic filaments (1) and a resin filament (2) twisted together, the resin filament (2) being made from a polymeric material having a melting point or softening point of 80 to 160°C. The cord for reinforcing elastomers includes a core and at least one sheath layer, wherein, after vulcanization, a distance w between metallic filaments (1b) forming an outermost sheath layer is 100 µm or less, and, on a cross section of the cord taken along a direction orthogonal to an axial direction, a filling ratio, which is a ratio of an area of a polymeric material (3) derived from the resin filament (2) to a gap region is 52 to 120%, where the gap region is defined as a portion occupied by a material other than the metallic filaments (1) within a region formed by connecting the centers of the individual metallic filaments (1b) constituting the outermost sheath layer.