Fully Fluorinated Thermoplastic Plain Bearing Cold Flow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional dry-running plain bearings made from PTFE and high-performance thermoplastics face issues with cold flow properties, leading to poor service life, especially under high sliding speeds and temperatures, and are limited by mechanical and chemical properties when filled with additives.
Innovation Solution
The use of fully fluorinated thermoplastic polymer materials with specific comonomer contents, such as Moldflon, which have improved cold flow and wear properties without the need for fillers, allowing for higher sliding speeds and temperatures, and maintaining universal chemical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard PTFE or chemically modified PTFE is used in plain bearings, then sliding friction is optimized, but cold flow properties deteriorate leading to poor service life
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition of PTFE through the incorporation of specific comonomers (hexafluoropropylene, perfluoroalkyl vinyl ether, perfluoro(2,2-dimethyl-1,3-dioxole), or chlorotrifluoroethylene) in controlled amounts (0.1-10 mol%). This chemical parameter modification transforms standard PTFE into copolymers with improved cold flow resistance while preserving low friction coefficients, directly resolving the contradiction between optimized sliding friction and deteriorated cold flow properties
Solution Approach 2:
The patent creates composite material structures by combining PTFE base polymer with specific comonomer units in copolymer form. This composite approach at the molecular level allows the material to exhibit both the low friction characteristics of PTFE and the enhanced dimensional stability from the comonomer structures, eliminating the need for filler additions that would compromise cold flow properties
2Stability of the object's composition
If fillers such as glass, bronze, or carbon particles are added to improve cold flow behavior, then cold flow properties improve, but mechanical properties, friction coefficients, and chemical resistance are negatively affected
Solution Approach 1:
The patent extracts and eliminates the need for filler additions by addressing the root cause of cold flow issues through copolymerization. Instead of adding external fillers (glass, bronze, carbon particles) that compromise chemical resistance and mechanical properties, the invention incorporates comonomer units directly into the polymer chain structure, achieving cold flow resistance through molecular architecture rather than particulate reinforcement
Solution Approach 2:
The patent changes the fundamental chemical parameter of the PTFE structure by introducing comonomer units with specific molecular configurations. These structural parameter changes at the polymer chain level provide cold flow resistance without the need for filler materials, thereby preserving the excellent chemical resistance and mechanical properties inherent to fluoropolymer materials
3Reliability
If high proportions of PTFE are used to optimize sliding friction, then sliding friction is improved, but cold flow properties deteriorate
Solution Approach 1:
The patent resolves this contradiction by changing the chemical composition parameters of PTFE itself through copolymerization. Instead of using high proportions of standard PTFE (which has poor cold flow resistance), the invention employs PTFE copolymers with specific comonomer contents (0.1-10 mol%), achieving both low sliding friction and improved cold flow properties through molecular structure modification rather than compositional proportion adjustment
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
These materials enable plain bearings to operate at circumferential speeds above 5 m/s with improved wear resistance and chemical resistance, extending service life and expanding application possibilities, including high-temperature and high-pressure conditions.
Implementation Method 1
The two main influencing factors in solid friction are adhesion and deformation in the contact surface. The coefficient of friction is accordingly made up of an adhesive component, which is proportional to the real contact area
Implementation Method 2
Since plastics are generally poor conductors of heat, the sliding surface often has a higher temperature than the entire bearing. While the sliding surface, as the place where heat is generated, determines the coefficient of friction and wear
Implementation Method 3
In the case of sliding friction, a stick-slip effect is often observed, which often occurs when the static coefficient of friction (friction coefficient) is greater than the dynamic coefficient (kinetic friction coefficient) or when, in a system capable of oscillation, the coefficient of friction decreases with increasing sliding speed
Data Source
Figure 1~2
Figure 3~4
AI summary
In order to provide a plain bearing with increased performance, particularly during dry running, and which tolerates higher sliding speeds than previously common over long operating periods, especially under these conditions, it is proposed that the plain bearing have a bearing body in which a bearing bushing is formed, the surface of which is made at least partially from a plastic material, wherein the plastic material comprises a fully fluorinated thermoplastic polymer material, optionally compounded with a proportion of one or more other high-performance thermoplastics selected from polyetherketones, polyphenylene sulfide (PPS), polyphenylene sulfone (PPSO2), polyamide (PA), polyimide (PI), polyamide-imide (PAI) and/or polyetherimide (PEI), as well as copolymers and derivatives of these polymers and copolymers.