PTFE Sliding Bearing with PPVE for Low-Temperature Operation
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Solution Overview
Problem
Current sliding bearings for constructions, particularly those using polytetrafluoroethylene (PTFE) materials, face limitations in temperature range, with PTFE being unsuitable for temperatures below -35°C and above 48°C, leading to increased friction and wear due to reduced plasticity and increased shear resistance at low temperatures, and poor compressive strength.
Innovation Solution
Modification of PTFE with perfluoropropylvinylether (PPVE) in percentages ranging between 0.1% and 0.3% by weight, creating a homopolymer with enhanced mechanical properties, including reduced shear resistance, increased density, and maintaining low friction coefficients even at extreme temperatures, thus extending the operational range of sliding bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pure PTFE is used as sliding material, then low friction coefficient is achieved, but temperature range is limited (-35°C to 48°C)
Solution Approach 1:
The patent uses a composite material consisting of PTFE combined with polyethylene (PE) or polypropylene (PP) to create a sliding surface that maintains low friction properties while extending the operational temperature range below -35°C. The composite structure combines the low friction characteristics of PTFE with the low-temperature flexibility of PE or PP.
Solution Approach 2:
The patent modifies the chemical composition parameters of the sliding material by incorporating specific ratios of PTFE with PE or PP (e.g., 80-95% PTFE and 5-20% PE/PP) to alter the material's physical properties, particularly its behavior at low temperatures, while maintaining acceptable friction characteristics.
2Temperature
If PTFE is used at low temperatures below -35°C, then material becomes more rigid, but friction increases and wear resistance decreases
Solution Approach 1:
The patent employs a composite material system where PTFE is combined with polyethylene or polypropylene to create a sliding surface that maintains low friction and good wear resistance at low temperatures. The PE or PP component prevents excessive rigidity and maintains plasticity below -35°C, while PTFE provides the low friction coefficient.
Solution Approach 2:
The sliding surface is designed with a specific composition distribution where PTFE provides the low-friction characteristic while the incorporated PE or PP provides the low-temperature flexibility, creating different functional zones within the same material structure to address conflicting requirements.
3Reliability
If PTFE is used for sliding surfaces, then low friction is achieved, but compressive strength is poor
Solution Approach 1:
The patent creates a composite sliding material combining PTFE with PE or PP, where the additional polymer components enhance the compressive strength and load-bearing capacity while the PTFE component maintains the low friction coefficient. This composite structure allows the material to withstand higher compressive loads than pure PTFE.
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 modified PTFE with PPVE maintains exceptionally low friction coefficients and improved wear resistance down to -50°C, allowing sliding bearings to operate beyond the conventional temperature limits, with potential for use in both low and high-temperature applications, and reducing creep and cold flow phenomena.
Implementation Method 1
the exceptional sliding properties of PTFE are due to a transfer process of PTFE molecules that occurs when a first surface of PTFE slides on a second surface made of a different material
Implementation Method 2
PTFE has a poor resistance to shear, generally lower than the adhesion forces that are generated between PTFE and the material of the second surface
Implementation Method 3
achieving a sliding resistance that is remarkably lower than the sliding resistance that would characterize PTFE and the metal material of the second surface
Implementation Method 4
a homopolymer of polytetrafluoroethylene (PTFE) modified with perfluoropropylvinylether (PPVE) in percentages ranging between 0.1% and 0.3% by weight
Implementation Method 5
maintaining low friction coefficients even at extreme temperatures, with potential for use in both low and high-temperature applications
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a sliding bearing (110, 210; 310) for constructions, said bearing (110; 210; 310) comprising at least one first and one second components (111; 112; 211, 212, 213; 311, 312, 313) operably connected to one another and configured to withstand a vertical or transverse load, as well as at least one pair of sliding surfaces (121, 122; 221, 222, 223, 224; 321, 322, 323, 324) arranged between said first and second components so as to allow mutual movements and/or rotations thereof. One of the sliding surfaces (121; 221, 223; 321, 323) of the pair of sliding surfaces is a plate made of a polymeric material mounted on one between the first and second components and the other sliding surface (122; 222, 224; 322, 324) is a metal surface associated to at least a portion of the face of the other member facing the polymeric material plate. The polymeric material plate is made of polytetrafluoroethylene (PTFE) modified by addition of perfluoropropylvinylether (PPVE) in percentages ranging between 0.1% and 0.3% by weight.