Sulfur-Containing Polyalkylene Glycol Lubricant Thermo-Oxidative Stability
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Solution Overview
Problem
Conventional polyalkylene glycol (PAG) lubricants suffer from oxidative instability and require high antioxidant levels for thermo-oxidative stability, which is undesirable, especially in high-temperature applications where water-based lubricants evaporate and hydrocarbon oils are combustible.
Innovation Solution
A sulfur-containing polyalkylene glycol (S-PAG) base oil with less than 1% water and an antioxidant, such as octylated/diphenylamine, providing enhanced fire resistance and thermo-oxidative stability, reducing dependence on antioxidant levels for stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PAGs are used as base oil, then lubricating capabilities are provided, but oxidative instability occurs requiring high antioxidant levels
Solution Approach 1:
The patent changes the chemical composition parameter of the base oil by incorporating sulfur-containing polyalkylene glycol with specific molecular weight (500-5000 g/mol) and sulfur content (0.1-10 wt%), which fundamentally alters the oxidative stability characteristics without requiring high antioxidant levels
Solution Approach 2:
The invention creates a composite base oil system combining sulfur-containing polyalkylene glycol with specific antioxidants (0.01-5 wt%), where the sulfur-containing polymer provides inherent oxidative stability that synergizes with the antioxidant to achieve superior thermo-oxidative stability at lower antioxidant concentrations
2Object-affected harmful factors
If water-based lubricants are used, then fire resistance is improved, but evaporation occurs at high temperatures
Solution Approach 1:
The patent changes the base oil composition from water-based to sulfur-containing polyalkylene glycol, which has high flash point (>200°C) and negligible vapor pressure at operating temperatures, simultaneously achieving fire resistance and high temperature stability
3Ease of operation
If hydrocarbon oils are used, then lubricating properties are provided, but combustibility increases
Solution Approach 1:
The patent changes the chemical composition from hydrocarbon-based to sulfur-containing polyalkylene glycol, which has inherently higher flash point and fire resistance while maintaining lubricating properties through its molecular structure and interaction with metal surfaces
4Reliability
If antioxidant levels are increased for conventional PAGs, then thermo-oxidative stability is improved, but cost and complexity increase
Solution Approach 1:
The patent changes the base oil chemistry to sulfur-containing polyalkylene glycol, which provides inherent oxidative stability that reduces dependence on high antioxidant concentrations, thereby simplifying the overall formulation
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 S-PAG fluid exhibits surprisingly high fire resistance and thermo-oxidative stability, maintaining performance and extending the fluid's lifetime by minimizing degradation due to oxidation, even at high temperatures.
Implementation Method 1
the base oil consisting of a sulfur-containing polyalkylene glycol... exhibiting surprisingly high fire resistance and thermo-oxidative stability... minimizing degradation due to oxidation
Implementation Method 2
exhibiting surprisingly high fire resistance and thermo-oxidative stability
Data Source
AI summary
A fluid contains a base oil and an antioxidant, the base oil consisting of sulfur-containing polyalkylene glycol where greater than 80 weight-percent of the fluid is a sulfur-containing polyalkylene glycol and less than one weight-percent of the fluid is water, with weight percent based on total fluid weight an wherein the sulfur-containing polyalkylene glycol is free of oxygen bound directly to sulfur.