Ethylene-Acrylic Rubber Composition for Bonded Piston Seals

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Solution Overview

Problem

Existing bonded piston sealings (BPS) require secondary crosslinking, which increases process costs and can degrade compression set and crosslinking bonding properties, especially when using sulfur crosslinking-based acrylic rubber.

Innovation Solution

An ethylene-acrylic rubber composition with 1 to 7 PHR of calcium hydroxide is mixed with a binary ethylene-acrylic rubber polymer, allowing for primary peroxide-crosslinking without secondary crosslinking, enhancing compression set and crosslinking bonding properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If secondary crosslinking is performed to improve compression set, then compression set improves, but process cost increases and crosslinking bonding property deteriorates

Engineering Contradiction:
Improvecompression setVSAvoidprocess cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The invention extracts and eliminates the secondary crosslinking step from the traditional two-step crosslinking process. By using peroxide-crosslinkable binary ethylene-acrylic rubber and optimizing the primary crosslinking conditions, the patent achieves both compression set improvement and crosslinking bonding enhancement without requiring the separate secondary crosslinking step, thereby reducing process cost and avoiding the deterioration of crosslinking bonding property

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the crosslinking parameters by using peroxide-based primary crosslinking with specific catalysts and optimizing temperature and time conditions. This parameter optimization allows the primary crosslinking to achieve both compression set improvement and crosslinking bonding enhancement simultaneously, making the secondary crosslinking step unnecessary

Inventive Principle:
Principle #35Parameter changes

2Reliability

If secondary crosslinking is performed to improve compression set, then compression set improves, but crosslinking bonding property deteriorates

Engineering Contradiction:
Improvecompression setVSAvoidcrosslinking bonding property
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention extracts and eliminates the secondary crosslinking step from the traditional two-step crosslinking process. By using peroxide-crosslinkable binary ethylene-acrylic rubber and optimizing the primary crosslinking conditions, the patent achieves both compression set improvement and crosslinking bonding enhancement without requiring the separate secondary crosslinking step, thereby reducing process cost and avoiding the deterioration of crosslinking bonding property

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention uses a composite approach by combining peroxide-crosslinkable binary ethylene-acrylic rubber with specific catalysts and additives. This composite material system enables the primary crosslinking to achieve both compression set improvement and crosslinking bonding enhancement simultaneously, eliminating the need for secondary crosslinking

Inventive Principle:
Principle #40Composite materials

3Reliability

If binary type AEM is used to achieve excellent compression set without secondary crosslinking, then compression set improves, but crosslinking bonding property deteriorates

Engineering Contradiction:
Improvecompression setVSAvoidcrosslinking bonding property
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention changes the crosslinking parameters by using peroxide-based primary crosslinking with specific catalysts and optimizing temperature and time conditions. This parameter optimization allows the primary crosslinking to achieve both compression set improvement and crosslinking bonding enhancement simultaneously, making the secondary crosslinking step unnecessary

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite approach by combining peroxide-crosslinkable binary ethylene-acrylic rubber with specific catalysts and additives. This composite material system enables the primary crosslinking to achieve both compression set improvement and crosslinking bonding enhancement simultaneously, eliminating the need for secondary crosslinking

Inventive Principle:
Principle #40Composite materials

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 achieves excellent compression set and crosslinking bonding without secondary crosslinking, matching traditional materials' performance while reducing production costs and improving Mooney scorch properties and physical properties.

Implementation Method 1

a binary type AEM that contains ethylene applicable with peroxide-crosslinking

Methodology Applied
Scientific EffectPeroxide-crosslinking: Chemical Bonding

Implementation Method 2

The crosslinking density of the ACM is increased by causing secondary crosslinking therein

Methodology Applied
Scientific EffectCrosslinking: Chemical Bonding

Data Source

PatentUS10294345B2Ethylene-acrylic rubber composition, ethylene-acrylic rubber, rubber metal composite, and bonded piston sealing
Publication Date: 2019.05.21 NOK CORP

AI summary

An object of the present invention is to provide an ethylene-acrylic rubber composition that is excellent in the compression set and also in the crosslinking bonding even when no secondary crosslinking is caused therein, an ethylene-acrylic rubber produced by causing primary crosslinking in the composition, a rubber metal composite formed by bonding the ethylene-acrylic rubber and a metal with each other, and a bonded piston sealing including the rubber metal composite. The object is achieved by an ethylene-acrylic rubber composition including 1 to 7 PHR by weight of calcium hydroxide relative to 100 PHR by weight of a binary ethylene-acrylic rubber polymer that includes ethylene and an acrylic acid ester, an ethylene-acrylic rubber produced by causing peroxide-crosslinking by primary crosslinking in the ethylene-acrylic rubber composition, a rubber metal composite formed by crosslinking-bonding the ethylene-acrylic rubber and a metal with each other bonded with the primary crosslinking, and a bonded piston sealing including the rubber metal composite.