EPDM Rubber-Metal Composition for Cobalt-Free Adhesion
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Solution Overview
Problem
Rubber compositions containing ethylene-propylene-diene rubber (EPDM) fail to exhibit satisfactory adhesion to metal members when using cobalt-free adhesion promoters, specifically those disclosed in prior art, leading to durability and weatherproofness issues in rubber articles like hoses, conveyor belts, and tires.
Innovation Solution
A rubber composition comprising EPDM with a rubber-metal adhesion promoter, such as a metal salt of aliphatic carboxylic acid or a compound represented by formula [(RCOO)xMO]3Z, and a vulcanization accelerator other than thiuram-based compounds, ensuring excellent adhesion to metal members without using cobalt salts, thereby enhancing durability and weatherproofness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If cobalt-free adhesion promoters are used in rubber compositions containing EPDM, then environmental compliance is improved, but adhesion force between rubber and metal member deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the adhesion promoter by selecting specific metal salts (zinc, calcium, magnesium, sodium, potassium, ammonium) with particular fatty acid compositions (saturated, unsaturated, or mixed). By adjusting the carbon chain length, saturation level, and metal type, the patent achieves both environmental compliance (cobalt-free) and satisfactory adhesion force in EPDM-containing rubber compositions.
Solution Approach 2:
The patent employs composite adhesion promoter systems combining multiple metal salts with different fatty acid components. This composite approach allows the formulation to achieve synergistic effects where the combination of different metal salts and fatty acids provides both environmental compliance and effective adhesion promotion that individual components cannot achieve alone.
2Reliability
If EPDM is added to improve weatherproofness, then weather resistance is improved, but adhesion to metal members deteriorates
Solution Approach 1:
The patent addresses the incompatibility between EPDM and traditional adhesion promoters by changing the chemical parameters of the adhesion promoter system. Specifically, it uses non-cobalt metal salts combined with particular fatty acid types (saturated, unsaturated, or mixed) that are compatible with EPDM's chemical structure, thereby maintaining weatherproofness while achieving adequate adhesion.
3Object-affected harmful factors
If conventional adhesion promoters are replaced with cobalt-free alternatives, then environmental regulations compliance is improved, but adhesion performance deteriorates
Solution Approach 1:
The patent systematically adjusts multiple parameters of the adhesion promoter including metal type (zinc, calcium, magnesium, sodium, potassium, or ammonium), fatty acid saturation (saturated, unsaturated, or mixed), and carbon chain characteristics. These parameter changes enable the formulation to meet REACH regulation requirements while maintaining reliable adhesion performance.
Solution Approach 2:
The patent utilizes composite formulations combining multiple metal salts with various fatty acid components to achieve adhesion performance comparable to cobalt-based systems. The synergistic interaction between different components in the composite adhesion promoter enables both regulatory compliance and functional performance.
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 rubber composition achieves excellent adhesion to metal members and improved durability in rubber articles like hoses, conveyor belts, and tires, surpassing the performance of compositions containing cobalt salts, while adhering to environmental regulations by avoiding cobalt usage.
Implementation Method 1
adhesion force between the reinforcing material and the coating rubber
Implementation Method 2
rubber-metal adhesion promoter contains at least one selected from the group consisting of: (1) a metal salt of aliphatic carboxylic acid; and (2) a compound represented by general formula (A)
Implementation Method 3
vulcanization accelerator other than a thiuram-based compound
Data Source
AI summary
The present disclosure aims at providing an EPDM-containing rubber composition capable of exhibiting excellent adhesion to a metal member without necessitating inclusion of a cobalt salt of organic acid therein. Specifically, a rubber composition includes therein: a rubber component containing ≥20 phr of EPDM; a rubber-metal adhesion promoter; a vulcanization accelerator other than a thiuram-based compound; and no thiuram-based vulcanization accelerator, wherein the rubber-metal adhesion promoter contains a specifically formulated metal salt of aliphatic carboxylic acid.