Self-lubricating sliding bearing

Abstract

The invention relates to the technical field of sliding bearings, and discloses a self-lubricating sliding bearing which structurally comprises a metal support body, a self-lubricating sliding layer arranged on the metal support body and made of modified polytetrafluoroethylene as a base material, and a middle layer for connecting the metal support body and the self-lubricating sliding layer. The self-lubricating sliding bearing is characterized in that the modified polytetrafluoroethylene sliding layer is bonded on the metal support body by using a thermoplastic fluorine-free polymer film at least comprising a first thermoplastic polymer film and a second thermoplastic polymer film as an intermediate layer substrate. The first thermoplastic polymer film and the second thermoplastic polymer film are sequentially arranged and stacked on the metal supporting body in the thickness direction and used in a composite mode to form a middle layer connecting the sliding layer and the metal supporting body. According to the invention, the thermoplastic fluorine-free polymer is creatively used for replacing a fluorine-containing polymer as an intermediate layer base material for the first time to fix the polytetrafluoroethylene sliding layer on the metal support body, so that the use of a fluorine-containing material is reduced, and a guidance reference is provided for the replacement of the fluorine-containing material.

Description

Technical Field

[0001] This invention relates to the field of sliding bearing technology, and more particularly to a self-lubricating sliding bearing. Background Technology

[0002] Self-lubricating sliding bearings are mechanical components that achieve lubrication solely through their own material without the need for external lubricants. They offer advantages such as low maintenance costs, long service life, stable operation, and high durability, and are widely used in the machinery, aerospace, and automotive industries. Self-lubricating sliding bearings typically use a metal substrate to prepare the support body and a self-lubricating sliding layer made of a polymer with self-lubricating properties. Polytetrafluoroethylene (PTFE) has the lowest coefficient of friction, excellent self-lubricating properties, and strong resistance to high temperatures and chemical corrosion, making it widely used in the production of self-lubricating sliding bearings. However, its unique molecular structure results in extremely low surface energy, making it difficult to bond with metal materials. Therefore, in industrial production, an intermediate layer is usually used to connect the metal support body and the PTFE sliding layer.

[0003] For example, Chinese patent application CN101715392A discloses a maintenance-free, self-lubricating sliding bearing that uses a fluoropolymer as an intermediate layer to bond a polytetrafluoroethylene sliding layer to a metal support. However, fluoropolymers are difficult to process, expensive, and have a long degradation cycle, causing significant environmental pollution. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a self-lubricating sliding bearing that uses a fluoropolymer to bond a polytetrafluoroethylene sliding layer to a metal support. The selected fluoropolymer is a general-purpose polymer with a wide range of raw material sources, low processing difficulty, and low price, making it particularly suitable for industrial production.

[0005] The specific technical solution of the present invention is as follows: a self-lubricating sliding bearing, comprising a metal support, a self-lubricating sliding layer with polytetrafluoroethylene substrate disposed on the metal support, and an intermediate layer connecting the metal support and the self-lubricating sliding layer, wherein the intermediate layer is formed of a thermoplastic non-fluoropolymer film and contains functional groups of formula (I) and formula (II). (I) (II).

[0006] Formula (I) is an amide group, and formula (II) is a benzene ring.

[0007] Preferably, the intermediate layer is formed by compositing multiple thermoplastic fluoropolymer films, wherein the multiple thermoplastic fluoropolymer films include at least a first thermoplastic fluoropolymer film and a second thermoplastic fluoropolymer film, wherein the first thermoplastic fluoropolymer film contains functional groups of formula (I); and the second thermoplastic fluoropolymer film contains functional groups of formula (II); during the process of compositing the first thermoplastic polymer film and the second thermoplastic polymer film to form the intermediate layer, the first thermoplastic polymer film undergoes a chemical reaction under high temperature to generate one or more functional groups of formula (III), formula (IV) or formula (V); (III) (IV) (V).

[0008] Formula (III) is a carbonyl group, formula (IV) is a carboxyl group, and formula (V) is a terminal amide group.

[0009] Preferably, the melting points of both the first thermoplastic fluoropolymer film and the second thermoplastic fluoropolymer film exceed 200°C.

[0010] Preferably, the metal support, the first thermoplastic fluoropolymer film, the second thermoplastic fluoropolymer film, and the self-lubricating sliding layer are sequentially stacked along the thickness direction, and the first thermoplastic fluoropolymer film and the second thermoplastic fluoropolymer film are used together to form an intermediate layer.

[0011] Optionally, the first thermoplastic fluoropolymer film substrate is selected from thermoplastic polyamide; the second thermoplastic fluoropolymer film substrate is selected from a high-temperature resistant polymer with a benzene ring structure in its molecular chain, preferably thermoplastic polyphenylene sulfide.

[0012] Thermoplastic polyamide film contains amide groups that have good affinity with metals, and at the same time possesses excellent flexibility and ductility, which makes up for the shortcomings of thermoplastic polyphenylene sulfide film, which is prone to breakage and delamination due to its excessive rigidity. Thermoplastic polyphenylene sulfide film also makes up for the deficiency of thermoplastic polyamide film in high temperature resistance with its excellent high temperature resistance. Therefore, the intermediate layer formed by the composite use of thermoplastic polyamide film and thermoplastic polyphenylene sulfide film has a strong bonding effect on the metal support and sliding layer and has strong resistance to high temperature environment.

[0013] Optionally, the thermoplastic polyamide film comprises 1%-20% thermoplastic polyethylene by weight, based on the total mass of the thermoplastic polyamide film.

[0014] Preferably, the thermoplastic polyamide film comprises 1%-10% thermoplastic polyethylene by weight.

[0015] Optionally, the thickness of the thermoplastic polyamide film ranges from 10 to 100 μm, and the thickness of the thermoplastic polyphenylene sulfide film ranges from 10 to 100 μm.

[0016] Preferably, the thermoplastic polyamide film has a thickness of 25 μm, and the thermoplastic polyphenylene sulfide film has a thickness of 50 μm.

[0017] Optionally, the first and second thermoplastic fluoropolymer films contain one or more of the following functional fillers: thermally conductive, electrically conductive, and wear-resistant, to improve the thermal conductivity, electrical conductivity, or wear resistance of the intermediate layer. The functional filler is selected from graphite, graphene, carbon nanotubes, molybdenum disulfide, silicon dioxide, ultra-high molecular weight polyethylene, aromatic polyesters, and liquid crystal polymers.

[0018] Optionally, the thermoplastic polyamide film and the thermoplastic polyphenylene sulfide film are treated with plasma or high-energy ultraviolet light.

[0019] Preferably, the self-lubricating sliding layer is prepared from modified polytetrafluoroethylene, and the modified filler material includes one or more of wear-resistant, conductive, and thermally conductive fillers. The wear-resistant filler material is selected from carbon black, graphite, graphene, carbon nanotubes, molybdenum disulfide, silicon dioxide, barium sulfate, polyamide, polyamide-imide, polyetheretherketone, polyphenylene sulfide, etc.; the conductive and thermally conductive fillers are both conventional materials with these functions in the art.

[0020] Optionally, the thickness of the modified polytetrafluoroethylene film ranges from 0.1 to 0.25 mm, preferably 0.2 mm.

[0021] Optionally, the surface of the self-lubricating sliding layer near the metal support is treated to enhance its adhesion to the metal support. Preferably, its surface structure is altered by chemical etching with sodium naphthalene solution to introduce polar functional groups and increase surface roughness.

[0022] Optionally, the side of the metal support near the self-lubricating sliding layer is subjected to surface treatment to enhance its adhesion to the surface sliding layer. The surface treatment is a physical treatment and / or a chemical modification treatment. The physical treatment is selected from one or more of sandblasting, wire drawing, grinding, and laser etching, preferably sandblasting; the chemical modification treatment is selected from one or more of spraying surface treatment agents, pickling, alkaline washing, phosphating, electrochemical treatment, and electroplating, preferably spraying surface treatment agents.

[0023] Preferably, the surface treatment of the metal support is to first sandblast and then spray a surface treatment agent, wherein the surface treatment agent is a silane coupling agent containing hydroxyl and / or carboxyl groups.

[0024] Optionally, the surface roughness Ra of the metal support substrate ranges from 0.5 to 3.0 μm, and preferably, the surface roughness Ra is 1.5 μm.

[0025] Optionally, the substrate of the metal support is selected from one or more of steel, stainless steel, aluminum, copper, and bronze, and the metal support is a single metal material or alloy, preferably steel plate.

[0026] Optionally, the thickness of the metal support is in the range of 0.2-0.3 mm, preferably 0.25 mm.

[0027] Compared with the prior art, the present invention has at least the following advantages: (1) This invention breaks through the conventional approach of relying on fluoropolymers as the intermediate layer substrate for bonding the self-lubricating sliding layer of polytetrafluoroethylene (PTFE) to the metal support in the prior art. It creatively selects a fluorine-free thermoplastic polymer to replace the fluoropolymer as the raw material for the intermediate layer. PTFE has extremely weak polarity and very low surface energy, resulting in poor compatibility with polar metals. The bonding between the two often relies on fluoropolymers (such as ETFE and FEP) as the intermediate layer, thus forming a technological inertia. However, the limited availability of raw materials for fluoropolymers, the high processing difficulty leading to high costs, and the long degradation cycle of fluoropolymers causing significant environmental pollution severely limit their application. This invention, for the first time, selects a fluorine-free thermoplastic polyamide film and a polyphenylene sulfide film. By combining the two to form an intermediate layer, the modified PTFE sliding layer is bonded to the metal support, proving the feasibility of using a fluorine-free polymer to replace the fluoropolymer as the intermediate layer. This breaks through the technological inertia and provides guidance for subsequent industrial production and related research. Moreover, compared with fluoropolymers, fluorine-free polymers have a wide range of raw material sources, are easier to process, have lower production costs, and cause less environmental pollution. Using fluorine-free polymers to replace fluorine-containing materials solves the bonding problem of polytetrafluoroethylene (PTFE) while also reducing costs and meeting environmental protection requirements, thus possessing significant industrial value.

[0028] (2) In this invention, thermoplastic polyamide and thermoplastic polyphenylene sulfide are selected to replace fluorine-containing materials as the substrate for bonding polytetrafluoroethylene self-lubricating sliding layer and metal support. The two thermoplastic polymers are general-purpose polymer materials with wide availability and low price, and are particularly suitable for industrial production. The solution proposed in this invention has great industrial value.

[0029] (3) The operating process disclosed in this invention is simple and efficient. This invention selects thermoplastic polyamide film and thermoplastic polyphenylene sulfide film as intermediate layer substrates, and sequentially sets and stacks the metal support, thermoplastic polyamide film, thermoplastic polyphenylene sulfide film, and modified polytetrafluoroethylene sliding layer. The thermoplastic polyamide film has good affinity with metal and excellent flexibility and ductility, which makes up for the shortcomings of thermoplastic polyphenylene sulfide film, which is prone to breakage and delamination due to its excessive rigidity. The thermoplastic polyphenylene sulfide film compensates for the deficiency of thermoplastic polyamide film in high temperature resistance with its excellent high temperature resistance. Moreover, the intense movement of the molecular chain segments of polyamide and polyphenylene sulfide in the molten state generates mutual entanglement, eliminating the interface between the two, and forming a stable intermediate layer structure. Therefore, the intermediate layer formed by the composite use of thermoplastic polyamide film and thermoplastic polyphenylene sulfide film not only has good affinity with metal support and high bonding strength between the two, but also has good toughness and high temperature resistance, which improves product quality.

[0030] (4) The material of the self-lubricating sliding layer of the present invention is modified polytetrafluoroethylene, which has a further improved anti-friction performance compared with unmodified polytetrafluoroethylene; at the same time, the use of metal materials is reduced, which effectively reduces the weight of the bearing and meets the requirements of automobile lightweighting; and compared with metal materials, polymers are simpler to process and consume less energy, which is more in line with the requirements of energy conservation and environmental protection. Attached Figure Description

[0031] Figure 1 This is a cross-sectional microstructure diagram of the self-lubricating sliding bearing of the present invention.

[0032] In the figure: 1. Metal support; 2. Self-lubricating sliding layer; 3. Thermoplastic polyamide layer; 4. Thermoplastic polyphenylene sulfide layer. Detailed Implementation

[0033] The present invention will now be described through specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Variations and advantages that can be conceived by those skilled in the art without departing from the spirit and scope of the inventive concept are included in the present invention, and the scope of protection of the present invention is defined by the appended claims and any equivalents thereof.

[0034] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Unless otherwise specified, the raw materials and equipment used in this invention are conventional in the art and can be obtained through conventional commercial means; unless otherwise specified, the methods used in this invention are conventional methods in the art.

[0035] In this invention, the functional groups of formulas (I), (II), (III), (IV), and (V) are: (I) (II) (III) (IV) (V).

[0036] Example 1: This invention provides a self-lubricating sliding bearing, comprising a metal support, a self-lubricating sliding layer with a modified polytetrafluoroethylene substrate disposed on the metal support, and an intermediate layer connecting the metal support and the self-lubricating sliding layer. The intermediate layer has a substrate of a thermoplastic fluoropolymer, formed by combining a first thermoplastic fluoropolymer film and a second thermoplastic fluoropolymer film. The first thermoplastic fluoropolymer film contains functional groups of formula (I), and the second thermoplastic fluoropolymer film contains functional groups of formula (II). It should be noted that, since the preparation process of the self-lubricating bearing involves high-temperature and high-pressure operation steps, the first thermoplastic fluoropolymer film will undergo a chemical reaction under such environment to generate one or more functional groups of formula (III), formula (IV), or formula (V).

[0037] The modified polytetrafluoroethylene (PTFE) used in this invention to prepare a self-lubricating sliding layer is a modified PTFE whose wear resistance, electrical conductivity, and thermal conductivity are significantly optimized by filling with functional materials. The functional filler materials are selected from one or more of the following: carbon black, graphite, graphene, carbon nanotubes, molybdenum disulfide, silicon dioxide, barium sulfate, polyamide, polyamide-imide, polyetheretherketone, and polyphenylene sulfide.

[0038] In a preferred embodiment of the present invention, the metal support is made of steel plate, which undergoes pretreatment before use, as follows: (1) Cleaning of steel plate: In this embodiment, the thickness of steel plate is 0.25mm. Before use, the steel plate is pickled, washed with water and dried to remove surface oxides and contaminants; (2) Physical treatment of steel plate surface: The cleaned steel plate is subjected to single-sided sandblasting. In this embodiment, in a closed environment, compressed air is used as power to spray steel sand at high speed onto the surface of the steel plate. The surface roughness of the steel plate is controlled by controlling the particle size of the steel sand. The surface roughness Ra range is 0.5-3.0μm, and the preferred surface roughness Ra is 1.5μm. (3) Chemical modification treatment of steel plate surface: In order to further enhance the bonding strength between the metal support and the lubricating layer, the steel plate after sandblasting is chemically modified. In this embodiment, the steel plate after sandblasting is cleaned and dried, and then an alcohol solution of surface treatment agent (silane coupling agent containing hydroxyl-OH and / or carboxyl-COOH) is uniformly sprayed onto the sandblasted surface of the steel plate and then dried.

[0039] In other embodiments, the steel plate may be subjected to physical treatment or chemical modification treatment alone, wherein the physical treatment is selected from sandblasting, wire drawing, grinding, and laser etching; the chemical modification treatment is selected from spraying surface treatment agent, pickling, alkaline washing, phosphating, electrochemical treatment, and electroplating.

[0040] In other embodiments, the thickness of the metal support ranges from 0.2 to 0.3 mm, and its base material can be one of steel, stainless steel, aluminum, copper, bronze, or a combination of the above metals; the material of the metal support is a single metal or alloy.

[0041] In a preferred embodiment of the present invention, the modified polytetrafluoroethylene film used as the self-lubricating sliding layer undergoes pretreatment, the steps of which are as follows: (1) Cleaning of modified polytetrafluoroethylene membrane In this embodiment, a modified polytetrafluoroethylene (PTFE) membrane with a thickness of 0.2 mm is preferred. The PTFE membrane is cleaned with anhydrous ethanol to remove oil and other contaminants from its surface, and then dried at 40-60°C for half an hour. (2) Treatment of modified polytetrafluoroethylene membrane with sodium naphthalene solution In this embodiment, the sodium naphthalene solution is prepared in an anhydrous and oxygen-free environment; the modified polytetrafluoroethylene membrane is treated with sodium naphthalene solution under the protection of nitrogen or argon for a treatment time of 10s-5min, preferably 2min; the modified polytetrafluoroethylene membrane after treatment with sodium naphthalene solution is washed sequentially with tetrahydrofuran / anhydrous diethyl ether, anhydrous ethanol and deionized water to remove sodium naphthalene adhering to the membrane surface.

[0042] In other embodiments, the thickness of the modified polytetrafluoroethylene film ranges from 0.1 to 0.25 mm.

[0043] The intermediate layer material used in this invention is preferably a thermoplastic polymer film.

[0044] In a preferred embodiment of the present invention, the intermediate layer is composed of multiple layers of thermoplastic fluoropolymer films, wherein the multiple layers of thermoplastic fluoropolymer films include at least a first thermoplastic fluoropolymer film and a second thermoplastic fluoropolymer film. The first thermoplastic fluoropolymer film contains functional groups of formula (I), which undergo a chemical reaction at high temperature to generate one or more functional groups of formula (III), formula (IV), or formula (V). The second thermoplastic fluoropolymer film contains functional groups of formula (II). The first thermoplastic fluoropolymer film is a thermoplastic polyamide film, and the second thermoplastic fluoropolymer film is a thermoplastic polyphenylene sulfide film.

[0045] (I) (II) (III) (IV) (V).

[0046] The metal support, thermoplastic polyamide film, thermoplastic polyphenylene sulfide film, and self-lubricating sliding layer are sequentially stacked along the thickness direction. The thermoplastic polyamide film and thermoplastic polyphenylene sulfide film are heated, melted, cooled, and solidified under pressure to form an intermediate layer.

[0047] To optimize the flexibility and processing flow of thermoplastic polyamide films, thermoplastic polyethylene is added to the thermoplastic polyamide films. In one embodiment, based on the total mass of the thermoplastic polyamide film, the mass percentage of conventional thermoplastic polyethylene is 10%.

[0048] In this embodiment, a steel plate is used as the metal support substrate, and a modified polytetrafluoroethylene (PTFE) film is used as the self-lubricating sliding layer substrate. The bonding steps of the modified PTFE are as follows: (1) Raw material preparation: The thermoplastic polyamide film is placed on the surface of the surface-treated steel plate of the metal support raw material. The thickness of the selected thermoplastic polyamide film is preferably 25 μm. The thermoplastic polyphenylene sulfide film is placed on the above polyamide film. The thickness of the selected thermoplastic polyphenylene sulfide film is preferably 50 μm. The modified polytetrafluoroethylene film is placed on the surface of the above polyphenylene sulfide film after treatment with sodium naphthalene solution. The thickness of the modified polytetrafluoroethylene film used is preferably 0.2 mm. (2) Hot pressing: After the hot press is heated to the operating temperature, pressure is applied under the protection of the polytetrafluoroethylene gasket. Under pressure, the thermoplastic polyamide film and thermoplastic polyphenylene sulfide film are melted. After the set time is reached, the heating is stopped, the upper and lower working plates maintain the original pressure, and the upper and lower working plates are cooled down quickly with compressed air. The molten thermoplastic polyamide film and thermoplastic polyphenylene sulfide film are cooled and solidified to form an intermediate layer to bond the modified polytetrafluoroethylene film to the steel plate. (3) Machining of self-lubricating sliding bearing: Cut the steel plate with modified polytetrafluoroethylene bonded to metal strips of specified size and cut the corners. Roll the metal strips into straight cylindrical bodies. The modified polytetrafluoroethylene film is the outer surface of the cylinder, and the surface of the steel plate without the modified polytetrafluoroethylene film is the inner surface. Flang and shape the cylinder to prepare a self-lubricating sliding bearing, and electro-zinc plate the exposed metal surface of the bearing.

[0049] In step (2) above, the operating parameters of the hot press are as follows: the temperature of the upper worktable of the hot press is 310℃, the temperature of the lower worktable is 310℃; the operating pressure is 1.5MPa; the heating operation time is set to 1800s; the pressure holding time is 1h, and compressed air is used to cool the upper and lower worktables during pressure holding.

[0050] The cross-sectional microstructure of the self-lubricating sliding shaft thus produced is as follows: Figure 1As shown, from bottom to top, the structure consists of a metal support 1, a thermoplastic polyamide layer 3, a thermoplastic polyphenylene sulfide layer 4, and a self-lubricating sliding layer 2.

[0051] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A self-lubricating sliding bearing, comprising a metal support, a self-lubricating sliding layer made of polytetrafluoroethylene disposed on the metal support, and an intermediate layer connecting the metal support and the self-lubricating sliding layer, characterized in that, The intermediate layer substrate is a thermoplastic fluoropolymer film containing functional groups of formula (I) and formula (II); (AND), (II)。 2. The self-lubricating sliding bearing according to claim 1, characterized in that, The intermediate layer is composed of multiple thermoplastic fluoropolymer films, which include at least a first thermoplastic fluoropolymer film and a second thermoplastic fluoropolymer film. The first thermoplastic fluoropolymer film contains functional groups of formula (I); the second thermoplastic fluoropolymer film contains functional groups of formula (II); the first thermoplastic fluoropolymer film undergoes a chemical reaction at high temperature to generate one or more functional groups of formula (III), formula (IV) or formula (V). (III)、 (IV)、 (V)。 3. The self-lubricating sliding bearing according to claim 2, characterized in that, The metal support, the first thermoplastic fluoropolymer film, the second thermoplastic fluoropolymer film, and the self-lubricating sliding layer are sequentially stacked along the thickness direction.

4. A self-lubricating sliding bearing according to claim 2, characterized in that, The first thermoplastic fluoropolymer film is a thermoplastic polyamide film; the second thermoplastic fluoropolymer film is a thermoplastic polyphenylene sulfide film.

5. A self-lubricating sliding bearing according to claim 4, characterized in that, The thermoplastic polyamide film comprises 1%-20% thermoplastic polyethylene by weight.

6. A self-lubricating sliding bearing according to claim 4, characterized in that, The thickness of the thermoplastic polyamide film ranges from 10 to 100 μm, and the thickness of the thermoplastic polyphenylene sulfide film ranges from 10 to 100 μm.

7. A self-lubricating sliding bearing according to claim 2, characterized in that, The first thermoplastic fluoropolymer film and the second thermoplastic fluoropolymer film contain one or more of the following: thermally conductive filler material, electrically conductive filler material, and wear-resistant filler material.

8. A self-lubricating sliding bearing according to claim 2, characterized in that, The first thermoplastic fluoropolymer film and the second thermoplastic fluoropolymer film are treated with plasma or high-energy ultraviolet light.

9. A self-lubricating sliding bearing according to claim 1, characterized in that, The polytetrafluoroethylene is modified polytetrafluoroethylene, which contains one or more of the following: conductive functional filler, thermally conductive functional filler, and wear-resistant functional filler.

10. A self-lubricating sliding bearing according to any one of claims 1 to 9, characterized in that, The side of the self-lubricating sliding layer near the metal support is chemically etched; the side of the metal support near the self-lubricating sliding layer is surface treated, which is a physical treatment and / or a chemical modification treatment.

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