Rubber Laminate Crosslinking for POE-Resistant Flexible Hoses
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rubber hoses with innermost layers made of butyl rubber face compatibility issues with POE-based lubricating oils, leading to swelling and poor mechanical properties, and existing bonding methods fail to maintain the characteristics of individual rubber layers, while hoses require improved vibration absorption and resistance to new refrigerants.
Innovation Solution
A rubber laminate comprising a butyl rubber layer crosslinked with an ethylene propylene diene rubber layer, using a low-molecular-weight polyolefin, phenolic resin, and organic peroxide crosslinking agent, with specific weight ratios to achieve strong bonding and retention of individual rubber characteristics, and a flexible hose structure with a thick butyl rubber layer for enhanced mechanical strength and vibration absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If butyl rubber is used for the innermost layer to maintain gas barrier properties, then gas resistance is improved, but compatibility with POE-based lubricating oils deteriorates causing swelling
Solution Approach 1:
The hose is divided into multiple layers with distinct functions: the innermost layer uses butyl rubber for gas barrier properties, while intermediate or outer layers use POE-resistant materials like NBR or crosslinked rubber compositions to provide oil resistance. This segmentation allows each layer to optimize its specific function without compromising the others.
Solution Approach 2:
The invention employs composite rubber structures where butyl rubber is combined with other rubber materials that have good POE oil resistance. The composite structure leverages the gas barrier properties of butyl rubber while incorporating materials resistant to POE-based lubricating oils, solving both requirements simultaneously.
2Stability of the object's composition
If NBR is blended into IIR to improve POE oil resistance, then compatibility with POE oil is improved, but gas barrier property deteriorates
Solution Approach 1:
Rather than blending NBR into IIR, the invention segments the hose structure into separate layers where butyl rubber (IIR) forms the innermost gas-barrier layer and NBR or other POE-resistant materials form intermediate or outer layers. This maintains the gas barrier property of pure butyl rubber while providing POE oil resistance in contact layers.
Solution Approach 2:
Different regions of the hose are assigned different material properties: the innermost layer contacting refrigerant gas uses pure butyl rubber for optimal gas barrier properties, while intermediate or outer layers contacting lubricating oil use POE-resistant materials. Each local region has the quality needed for its specific function.
3Ease of manufacture
If adhesive bonding is used to laminate IIR and NBR layers, then ease of manufacture is improved, but adhesion strength deteriorates
Solution Approach 1:
The invention replaces chemical adhesive bonding with peroxide crosslinking bonding. The peroxide penetrates the butyl rubber layer and forms crosslinks that chemically bond the layers together, providing adhesion strength comparable to or exceeding adhesive bonding while maintaining ease of manufacture through a single-step crosslinking process.
Solution Approach 2:
The bonding mechanism is changed from adhesive-based to crosslinking-based by introducing peroxide as a bonding agent. The peroxide undergoes decomposition and crosslinking reactions that create strong chemical bonds between layers, fundamentally changing the bonding parameter from mechanical/chemical adhesion to covalent crosslinking.
4Strength
If crosslinking is used to bond IIR and NBR layers, then adhesion strength is improved, but compatibility between layers deteriorates due to different SP values
Solution Approach 1:
Peroxide serves as an intermediary bonding agent that can crosslink both butyl rubber and POE-resistant rubber layers. The peroxide decomposes to form free radicals that initiate crosslinking in both rubber types, creating a strong bond between incompatible layers without requiring the layers themselves to be compatible with each other.
Solution Approach 2:
The invention changes the bonding mechanism from direct layer-to-layer crosslinking (which requires compatibility) to peroxide-mediated crosslinking. The peroxide acts as a universal crosslinking agent that can bond dissimilar rubber materials by forming crosslinks within each layer and creating interfacial bonds, overcoming the incompatibility issue.
5Stability of the object's composition
If polyamide resin is used for the innermost layer to achieve POE oil resistance, then compatibility with POE oil is improved, but vibration absorption characteristics deteriorate
Solution Approach 1:
The hose structure is segmented so that vibration absorption and POE oil resistance are provided by different layers. The innermost rubber layer (butyl or crosslinked rubber) provides vibration absorption and flexibility, while intermediate or outer layers provide POE oil resistance, eliminating the need for polyamide resin in the vibration-critical inner layer.
Solution Approach 2:
The hose uses a composite structure combining rubber materials with good vibration absorption properties with POE-resistant materials in different layers. This composite approach maintains the flexibility and vibration damping of rubber while incorporating POE resistance through material selection in appropriate layers.
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 results in a strongly bonded rubber laminate and flexible hose with excellent heat resistance, POE oil resistance, mechanical strength, and vibration absorption characteristics, suitable for use with POE-based lubricating oils and refrigerants, while maintaining the gas barrier properties of the individual rubber layers.
Implementation Method 1
a rubber laminate comprising a butyl rubber-containing layer stacked with an ethylene propylene diene rubber and/or ethylene propylene rubber-containing layer, wherein the ethylene propylene diene rubber and/or ethylene propylene rubber-containing layer contains a low-molecular-weight polyolefin, a phenolic resin, and a crosslinking agent, and has been crosslinked by a peroxide
Data Source
AI summary
An object is to provide a rubber laminate by crosslinking and bonding two rubber layers while retaining the characteristics of each rubber layer, instead of blending together different rubber components or using an adhesive, wherein an air conditioning hose obtained by applying such rubber laminate can also handle POE-based lubricating oils and retain vibration absorption characteristics. As a solution, a non-crosslinked rubber laminate is provided, which is a rubber laminate comprising a butyl rubber-containing layer stacked with an ethylene propylene diene rubber and/or ethylene propylene rubber-containing layer, wherein such non-crosslinked rubber laminate is characterized in that the ethylene propylene diene rubber and/or ethylene propylene rubber-containing layer is a rubber-containing layer that contains a low-molecular-weight polyolefin, a phenolic resin, and a crosslinking agent, where: the low-molecular-weight polyolefin is contained by 40 to 70 parts by weight, the phenolic resin is contained by 1 to 4 parts by weight, and the crosslinking agent is contained by at least 1 part by weight, relative to the ethylene propylene diene rubber and/or ethylene propylene rubber constituting a total of 100 parts by weight.