Multilayer Coolant Hose Structure for Oil and Heat Resistance
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Solution Overview
Problem
Cooling water hoses face limitations in resistance to coolant mixtures, engine oils, and high temperatures, with existing rubber mixtures either lacking sufficient media resistance or exhibiting poor dynamic suitability and heat resistance.
Innovation Solution
A hose structure featuring a peroxide-crosslinked EPM/EPDM inner layer, a diaminically crosslinked ACM or AEM intermediate layer, and a diamminically crosslinked ACM or AEM outer layer, with a reinforcement layer for pressure resistance, and an adhesive bond between layers for enhanced durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diaminically crosslinked ACM or AEM rubber mixture is used for the outer layer, then resistance to engine oils and hydraulic fluids is improved, but adhesion to the inner layer deteriorates
Solution Approach 1:
A silane-based adhesion promoter is applied as an intermediary layer between the peroxide-crosslinked inner layer and the diamine-crosslinked outer layer. This adhesion promoter contains both peroxide-reactive groups (to bond with the inner layer) and silane groups (to bond with the outer layer), thereby mediating the adhesion between the two incompatible rubber systems.
2Ease of manufacture
If peroxide crosslinking is used for both layers, then processing simplicity is improved, but dynamic suitability and heat resistance deteriorate
Solution Approach 1:
The crosslinking chemistry parameter is changed from peroxide for the outer layer to diamine crosslinking. This parameter change in the outer layer's crosslinking mechanism provides superior dynamic suitability and heat resistance compared to peroxide crosslinking, while the inner layer maintains peroxide crosslinking for coolant resistance.
3Productivity
If DOTG accelerator is used in the rubber mixture, then vulcanization speed is improved, but quality during vulcanization in presence of residual oxygen deteriorates
Solution Approach 1:
The problematic DOTG accelerator is extracted/removed from the rubber mixture formulation. This elimination removes the source of quality deterioration during vulcanization in the presence of residual oxygen, while alternative accelerators or vulcanization systems are used to maintain adequate vulcanization speed.
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 hose demonstrates improved resistance to engine oils, hydraulic fluids, and high temperatures, with increased temperature resistance and dynamic suitability, while avoiding the use of DOTG and maintaining quality during vulcanization in the presence of residual oxygen.
Implementation Method 1
Only peroxide-crosslinked rubber mixtures based on EPM or EPDM have this required resistance to coolant mixtures
Implementation Method 2
the second layer consists of a diaminically crosslinked and DOTG-free rubber mixture based on offcut-free ACM or an ACM offcut or on offcut-free AEM or an AEM offcut
Implementation Method 3
the first layer and the second layer forming an adhesive bond
Data Source
Figure 1
AI summary
The invention relates to a hose (1) which transports a coolant and comprises at least the following layer construction: a first layer (2) made of a cross-linked rubber mixture acting as a media-resistant inner layer having contact with the coolant; and a second layer (3) made of a cross-linked rubber mixture contacting the outside of the first layer (2), wherein the first layer (2) and the second layer (3) form an adhesive bond. The hose (1) according to the invention is characterized in that the inner layer (2) is made of a peroxide cross-linked rubber mixture based on scrap-free EPM or an EPM scrap or scrap-free EPDM or an EPDM scrap, and the second layer (3) is made of a diamine cross-linked and DOTG-free rubber mixture based on ACM or an ACM scrap or scrap-free AEM or an AEM scrap. The hose (1) typically further comprises a third layer (4) as a reinforcing layer and a fourth layer (5) as an outer layer made of a diamine cross-linked and DOTG-free rubber mixture resistant to external influences. The invention further relates to the particular applications and method variants for producing such a hose (1).