PFPE Fluorine Grease Composition for Low Shear-Rate Torque Variation
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Solution Overview
Problem
Fluorine grease used as a lubricant in sliding apparatuses exhibits significant shear rate dependence of apparent viscosity, leading to variations in torque, which can be problematic in heated or evacuated environments.
Innovation Solution
A lubricant composition comprising perfluoropolyether as a base oil and fluorine resin particles with a dissolved fluorine-containing polymer having a tetrafluoroethylene structure is used, reducing shear rate dependence of apparent viscosity by interacting with the thickener to disperse nonuniformly and reduce structural viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorine grease with fluorine resin particles is used as a lubricant, then the lubricant provides effective lubrication in heated or evacuated environments, but the apparent viscosity exhibits significant shear rate dependence causing torque variation
Solution Approach 1:
The patent uses a composite thickener system combining fluorine resin particles (5-20 μm) with fluorine-containing polymer fine particles (0.1-10 μm) dissolved in the base oil. This composite structure creates a network that maintains stable apparent viscosity across different shear rates while preserving lubrication effectiveness in heated or evacuated environments. The polymer-dissolved-thickener interacts with the fluorine resin particles to form a stabilized structural network.
Solution Approach 2:
The patent controls the particle size parameters of the thickener components, specifically using fluorine resin particles with diameter of 5-20 μm and fluorine-containing polymer fine particles with diameter of 0.1-10 μm. By optimizing these size parameters and their mass ratio (polymer particles: 1-50 mass% of total thickener), the apparent viscosity stability is improved while maintaining lubrication performance.
2Object-generated harmful factors
If fluorine resin particles are used as a thickener, then the lubricant achieves non-Newtonian fluid behavior with structural viscosity, but this causes shear rate dependence of apparent viscosity leading to torque variation in sliding apparatus
Solution Approach 1:
The patent creates a composite thickener system where fluorine-containing polymer fine particles (0.1-10 μm) are dissolved in the base oil and interact with fluorine resin particles (5-20 μm). This composite structure modifies the structural viscosity characteristics, maintaining adequate lubrication while reducing excessive shear rate dependence. The dissolved polymer forms a network that stabilizes the viscosity behavior.
Solution Approach 2:
The patent applies different functional characteristics to different size components of the thickener system. The larger fluorine resin particles (5-20 μm) provide the primary structural network for lubrication, while the smaller dissolved polymer particles (0.1-10 μm) fill in the gaps and stabilize the local structure, creating a multi-scale composite that balances structural viscosity with viscosity stability.
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 lubricant composition maintains low apparent viscosity at low shear rates and high apparent viscosity at high shear rates, minimizing torque variations across a wide shear rate range, thus stabilizing the sliding apparatus performance.
Implementation Method 1
a fluorine-containing polymer having a tetrafluoroethylene structure under a state in which the polymer is dissolved in the perfluoropolyether
Implementation Method 2
the lubricant composition maintains low apparent viscosity at low shear rates and high apparent viscosity at high shear rates, minimizing torque variations across a wide shear rate range
Data Source
AI summary
Provided is a lubricant composition having small shear rate dependence of its apparent viscosity. The lubricant composition includes a perfluoropolyether as a base oil, and fluorine resin particles as a thickener. The lubricant composition further includes a fluorine-containing polymer having a tetrafluoroethylene structure under a state in which the polymer is dissolved in the perfluoropolyether.