CN114801108A

CN114801108A - High-wear-resistance PVDF composite board and preparation method thereof

Info

Publication number: CN114801108A
Application number: CN202110183310.1A
Authority: CN
Inventors: 樊学峰; 孙志华
Original assignee: Zhejiang Changsheng Sliding Bearings Co Ltd
Current assignee: Zhejiang Changsheng Sliding Bearings Co Ltd
Priority date: 2021-02-09
Filing date: 2021-02-09
Publication date: 2022-07-29
Anticipated expiration: 2041-02-09
Also published as: CN114801108B

Abstract

The invention directly sinters the metal mesh on the metal plate, and directly extrudes the modified PVDF material made of PVDF, reinforced fiber and solid lubricant on the metal mesh through an extruder, and the PVDF composite plate is made through rolling. The modified PVDF material has good wear resistance, and the surface of the material has a microporous structure after being combined with a metal mesh, so that the modified PVDF material is suitable for grease lubrication. The PVDF composite board is suitable for reciprocating, rotating and swinging motion under high load and low speed by grease lubrication, and is applied to automobile steering gear bearing bushes, seat angle adjuster bushing systems and the like.

Description

High-wear-resistance PVDF composite board and preparation method thereof

Technical Field

The invention belongs to the technical field of sliding bearing materials, and particularly relates to a high-wear-resistance PVDF composite board and a preparation method thereof.

Background

The bearing bush (bearing shell) is the part of the sliding bearing contacting with the shaft neck, is in the shape of a tile-shaped semi-cylindrical surface, is very smooth, and is generally made of bronze, antifriction alloy, special engineering plastics, special ceramics and other wear-resistant materials. An exemplary bearing shell is shown in figure 1. When the sliding bearing works, a thin oil film playing a lubricating role is arranged between the bearing bush and the rotating shaft. If the lubrication is poor, direct friction exists between the bearing bush and the rotating shaft, and the friction generates high temperature. Although the bearing shells are typically made of high temperature resistant materials, the high temperatures generated by direct friction are still sufficient to burn them out. The bush may be burnt due to the factors of excessive load, excessive temperature, impurities in the lubricating oil or abnormal viscosity, and the like, so that the sliding bearing is damaged. Therefore, the material for bearing shells is required to have a low friction coefficient, high wear resistance, sufficient fatigue strength, good running-in properties, and good corrosion resistance.

Automobile steering gears are important components in automobile steering systems. A rack and pinion steering gear is a common steering gear, and has a basic structure including a pair of pinion gears and a rack gear engaged with each other, and the rack gear moves linearly when the pinion gears are rotated by a steering shaft. The rack of the automobile steering gear is supported by an automobile steering gear rack supporting gasket bush arranged on an automobile steering gear supporting seat. The automobile steering gear rack supporting lining bush has the following requirements on materials: 1. good abrasion resistance and self-lubricity; 2. because the load is higher, the material is required to have higher load-bearing capacity; 3. good shock resistance and impact load resistance, and the need for a thicker wear layer to bring about good noise elimination characteristics to adapt to a larger range of fit clearance; 4. because the bearing bush is provided with the stretching lug boss (the lug boss is used for positioning and installing the bearing bush and the supporting seat), certain ductility requirement is required on materials when the lug boss is machined, and otherwise, the lug boss is easy to crack.

The traditional bearing bush of the rack support gasket of the automobile steering gear is made of copper alloy material, but the copper alloy material has high friction coefficient when insufficient lubrication, no self-lubricating property, serious abrasion and noise generation in the movement process. Later, bushings with Polytetrafluoroethylene (PTFE) plastic layers have been introduced. Although the PTFE bearing bush has self-lubricating property and reduced friction coefficient, the traditional PTFE plastic layer is thinner and generally does not exceed 0.03mm, and because the bearing bush bears higher load and has a vibration working condition, the PTFE plastic layer is seriously worn under the working condition, and the PTFE plastic layer shakes obviously and has obvious noise in reciprocating motion.

Therefore, a novel composite board with excellent self-lubricating property, wear resistance and bearing resistance, a thick fabric layer, an elastic layer and good ductility is needed in the field to meet the requirements of the bearing bush material of the rack support lining of the automobile steering gear.

Disclosure of Invention

In view of the above problems, the present invention forms a PVDF composite sheet by directly sintering a metal mesh (e.g., a copper mesh) on a metal plate (e.g., a steel plate), and directly extruding a modified polyvinylidene fluoride (PVDF) material made of PVDF, reinforcing fibers, and a solid lubricant onto the copper mesh through an extruder, and rolling. The modified PVDF material has good wear resistance, and the surface of the material has a microporous structure after being combined with a metal mesh, so that the modified PVDF material is suitable for grease lubrication. The PVDF composite board has excellent self-lubricating property, wear resistance and bearing resistance, thicker precoat, elastic layer and good ductility, is suitable for reciprocating, rotating and swinging motion under high load and low speed by grease lubrication, and is applied to automobile steering gear bearing bushes, seat angle adjuster bush systems and the like.

Specifically, the invention provides a PVDF composite plate, which comprises a metal substrate, an elastic layer and a sliding layer, wherein the elastic layer is positioned between the metal substrate and the sliding layer, the elastic layer comprises a metal net and a sliding layer material filled in meshes of the metal net, the metal net is connected onto the metal substrate through sintering, the sliding layer and the sliding layer material filled in the meshes of the metal net are formed by rolling a resin composition extruded on the surface of the metal net, the resin composition comprises PVDF, reinforcing fibers and a solid lubricant, and the content of the PVDF, the content of the reinforcing fibers and the solid lubricant in the resin composition are 65-85 wt%, 2-15 wt% and 5-20 wt% based on the total weight of the resin composition.

In one or more embodiments, the metal substrate is a steel plate.

In one or more embodiments, the metal mesh is a copper mesh, the wire diameter of the copper mesh is preferably 0.1-0.35mm, and the mesh number of the copper mesh is preferably 40 ± 10 meshes.

In one or more embodiments, the sliding layer has a thickness of 0.08 to 0.2 mm.

In one or more embodiments, the PVDF is present in the resin composition in an amount of 75 to 82 wt%, the reinforcing fiber is present in an amount of 2 to 10 wt%, and the solid lubricant is present in an amount of 13 to 20 wt%, based on the total weight of the resin composition.

In one or more embodiments, the reinforcing fibers are selected from one or more of carbon fibers, glass fibers, potassium titanate whiskers, and calcium sulfate whiskers, preferably carbon fibers, the carbon fibers preferably having a monofilament diameter of 5 to 10 μm and a length of 70 to 150 μm.

In one or more embodiments, the solid lubricant is selected from PTFE, graphite, MoS ₂ One or more of carbon black, calcium fluoride, barium sulfate and silica, preferably including PTFE and graphite; preferably, the resin composition contains PTFE in an amount of 6 to 18 wt%, preferably 8 to 16 wt%, and graphite in an amount of 1 to 10 wt%, preferably 2 to 8 wt%, based on the total weight of the resin composition.

In one or more embodiments, the PVDF composite sheet has a coefficient of friction of 0.027, preferably 0.026, more preferably 0.025, more preferably 0.024, after 8 hours of testing with a sample size of Φ 42 × Φ 40 × 30mm, a load of 60MP, a speed of 1.5m/min, lubrication conditions of No. 3 lithium-based grease, and a wear of No. 45 steel having a roughness Ra of 0.4 μm.

In one or more embodiments, the PVDF composite sheet material has a wear loss after 8 hours of testing for steel No. 45 with a sample size of phi 42 × phi 40 × 30mm, a load of 60MP, a speed of 1.5m/min, lubrication conditions of No. 3 lithium-based grease, and a roughness Ra of 0.4 μm for a grinding part of 0.025mm or less, preferably 0.020mm or less, more preferably 0.018mm or less, and more preferably 0.015mm or less.

In one or more embodiments, the resin composition comprises PVDF, carbon fiber, PTFE, and graphite, and the PVDF is present in an amount of 65 to 85 wt%, preferably 75 to 82 wt%, the reinforcing fiber is present in an amount of 2 to 15 wt%, preferably 2 to 10 wt%, the PTFE is present in an amount of 6 to 18 wt%, preferably 8 to 16 wt%, and the graphite is present in an amount of 1 to 10 wt%, preferably 2 to 8 wt%, based on the total weight of the resin composition.

The invention also provides a method for preparing the PVDF composite board, which comprises the following steps: extruding a resin composition onto the surface of a metal mesh of a heated metal mesh metal substrate composite plate, and then rolling, wherein the metal mesh metal substrate composite plate is formed by sintering the metal mesh and a metal substrate, the resin composition comprises PVDF, reinforcing fibers and a solid lubricant, and based on the total weight of the resin composition, the content of PVDF in the resin composition is 65-85 wt%, the content of reinforcing fibers is 2-15 wt%, and the content of the solid lubricant is 5-20 wt%.

In one or more embodiments, the metal substrate is a steel plate.

In one or more embodiments, the extrusion temperature of the resin composition is 210 ℃ and 230 ℃, preferably 225. + -. 5 ℃.

In one or more embodiments, the heating temperature of the metal mesh metal substrate composite plate is 210-225 ℃, preferably 220 + -5 ℃.

In one or more embodiments, the metal mesh metal substrate composite plate is heated by induction heating.

In one or more embodiments, the rolling temperature is 165-180 ℃, preferably 170. + -. 5 ℃ and the rolling pressure is 60-100MPa, preferably 80. + -. 10 MPa.

In one or more embodiments, the sintering temperature for sintering the metal mesh and the metal substrate is 800-: 1 to 2: 1.

the invention also provides a PVDF composite board prepared by the method of any embodiment of the invention.

The invention also provides a preparation system of the composite plate, which comprises an unreeling machine, a guide roller, an induction heating furnace, an extruder, a rolling mill and a reeling machine, wherein the unreeling machine is used for unreeling the metal mesh metal substrate composite plate, the guide roller is arranged at the downstream of the unreeling machine and is used for controlling the movement direction of the metal mesh metal substrate composite plate, the induction heating furnace is arranged at the downstream of the guide roller and is used for heating the metal mesh metal substrate composite plate, a discharge port of the extruder is arranged between the induction heating furnace and the rolling mill and is used for extruding the resin composition to the metal mesh surface of the metal mesh metal substrate composite plate between the induction heating furnace and the rolling mill, the rolling mill is arranged at the downstream of the induction heating furnace and is used for rolling the metal mesh metal substrate composite plate loaded with the resin composition, the winding machine is arranged at the downstream of the rolling mill and used for winding the composite plate.

The invention also provides a resin composition, which comprises PVDF, reinforcing fibers and a solid lubricant, wherein the content of the PVDF in the resin composition is 65-85 wt%, the content of the reinforcing fibers is 2-15 wt%, and the content of the solid lubricant is 5-20 wt%, based on the total weight of the resin composition.

The present invention also provides for the use of a resin composition as described in any of the embodiments herein to improve the self-lubricity, wear resistance, ductility, noise resistance, anti-shudder, running-in, and/or load-bearing capacity of a PVDF composite sheet.

The present invention provides a sliding member made of the PVDF composite sheet according to any one of the embodiments herein or a sliding device including a sliding member made of the PVDF composite sheet according to any one of the embodiments herein; preferably, the sliding part is a bushing, a washer or a shim plate, preferably an automotive steering gear rack support bushing; preferably, the sliding device is a sliding bearing, an axle, a brake, an air compressor, a seat adjuster, a suspension system or a hydraulic element, preferably a steering rack support device of an automobile.

Drawings

Figure 1 shows an automotive steering gear rack support pad bushing and support seat.

FIG. 2 shows the surface microporous structure of a PVDF composite plate made of a woven mesh, FIG. 2(A) is the surface appearance, and FIG. 2(B) is a cross-sectional metallographic microscopic view; the surface of the plate is continuously provided with square grains, the sizes of the micropores are 0.69mm multiplied by 0.6mm, and the depth of the micropores is 0.008-0.013 mm.

FIG. 3 shows the surface microporous structure of a PVDF composite sheet produced by punching and stretching a mesh, FIG. 3(A) is the surface appearance, and FIG. 3(B) is a cross-sectional metallographic microscopic view; the surface is distributed in diamond micropores, the diameter of the micropores is 0.53-0.56mm, and the depth of the micropores is 0.01-0.02 mm.

FIG. 4 is a schematic view of a composite board preparation system of the present invention.

Fig. 5 is a schematic diagram of the opposite grinding form of the test piece and the opposite grinding piece in the swing friction test.

FIG. 6 is a schematic view of a test apparatus in a bending test.

FIG. 7 shows the appearance of the PVDF composite sheet sample of example 1 after the bending test.

Fig. 8 shows the appearance of the PVDF composite sheet sample of comparative example 4 after the bending test.

Figure 9 shows the steering gear support pad friction tester in a bench test.

Figure 10 shows the shape and dimensions of the test bearing shells in the bench test.

Fig. 11 shows the appearance of bearing shells made of the PVDF composite sheets of examples 1-5 and comparative examples 1-4 after bench testing.

Detailed Description

To make the features and effects of the present invention comprehensible to those skilled in the art, general description and definitions are made below with reference to terms and expressions mentioned in the specification and claims. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The theory or mechanism described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, i.e., the present disclosure may be practiced without limitation to any particular theory or mechanism. All features defined herein as numerical ranges or percentage ranges, such as amounts, amounts and concentrations, are for brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to cover and specifically disclose all possible subranges and individual numerical values (including integers and fractions) within the range. Herein, unless otherwise specified, the ratio refers to a mass ratio, the percentage refers to a mass percentage, and the part refers to a mass part.

In this context, for the sake of brevity, not all possible combinations of features in the various embodiments or examples are described. Therefore, the respective features in the respective embodiments or examples may be arbitrarily combined as long as there is no contradiction between the combinations of the features, and all the possible combinations should be considered as the scope of the present specification.

In order to provide a composite plate with excellent self-lubricating property, wear resistance and bearing resistance, a thicker fabric layer, an elastic layer and good ductility, the invention sinters a metal substrate and a metal mesh to form metallurgical bonding, and obtains a novel PVDF composite plate by adopting a laminating process (directly extruding a modified PVDF material onto a preheated metal mesh metal substrate composite plate through an extruder and then rolling) and preferably combining and optimizing a sliding layer material formula. The PVDF composite board has excellent self-lubricating property, wear resistance and bearing resistance, thicker fabric layer, elastic layer, good running property and good ductility, is suitable for reciprocating, rotating and swinging motions under high load and low speed of grease lubrication, and is particularly suitable for manufacturing a rack support bearing bush of an automobile steering gear. The manufacturing method of the PVDF composite board can realize flow line production, has low production cost and is green and environment-friendly.

The PVDF composite board comprises a metal substrate, a metal mesh layer and a sliding layer, or consists of the metal substrate, the metal mesh layer and the sliding layer. Wherein, the metal mesh layer is positioned between the metal substrate and the sliding layer. The metal net layer comprises a metal net and a sliding layer material filled in the meshes of the metal net, or consists of the metal net and the sliding layer material filled in the meshes of the metal net. The metal mesh is attached to the metal substrate by sintering. The sliding layer comprises or consists of a sliding layer material. Herein, the sliding layer is also referred to as a plastic layer, a resin layer.

Metal substrates suitable for use in the present invention include, but are not limited to, steel sheets, aluminum sheets, stainless steel sheets, and the like. In some embodiments, the metal substrate used in the present invention is a steel sheet. The steel sheet is preferably a carbon structural steel cold rolled steel sheet or strip, which may be, for example, SPCC, SAE 1010. The steel sheet is preferably a passivated steel sheet. The thickness of the metal substrate may be 0.5-2.5 mm.

The type of expanded metal suitable for use in the present invention is not particularly limited, and may be, for example, woven mesh, punched mesh, stretched mesh. The metal mesh suitable for use in the present invention is preferably a copper mesh. Herein, copper mesh has a broad meaning, including copper alloy mesh. The metal mesh suitable for use in the present invention is preferably a copper alloy mesh, for example a copper mesh made of QSn6.5-0.1 or QSn8-0.3 copper alloy. In some embodiments, the present invention uses a punched and stretched copper mesh or a woven copper mesh of QSn6.5-0.1 or QSn8-0.3 material. The wire diameter of the copper mesh is preferably 0.1 to 0.35mm, for example 0.1 to 0.3mm, 0.15. + -. 0.05mm, 0.25. + -. 0.05mm, 0.3. + -. 0.05 mm. The mesh number of the copper net can be 40 plus or minus 10 meshes and 40 plus or minus 5 meshes. In some embodiments, the present invention uses a woven copper mesh having a wire diameter of 0.1 to 0.35mm, such as 0.1 to 0.3mm, 0.15 + -0.05 mm, 0.25 + -0.05 mm, and a mesh count of 40 + -5. The mesh shape of the metal net is not particularly limited, and may be, for example, a diamond shape, a square shape, a circular shape, a semicircular shape, or the like. The diagonal length dimension of the diamond holes can be 950 +/-50 mm and 650 +/-50 mm respectively. In some embodiments, the invention uses a punched and drawn copper mesh having a wire diameter of 0.1 to 0.35mm, such as 0.3 + -0.05 mm, and diamond-shaped holes having diagonal length dimensions of 950 + -50 mm and 650 + -50 mm, respectively. The content (volume percentage) of the sliding layer material in the metal mesh layer is preferably 40% to 70%. The thickness of the metal mesh layer may be 0.2-0.5 mm. In the invention, the metal mesh layer has certain elasticity and can improve the impact resistance of the metal reinforced composite board, so the metal mesh layer is also called as an elastic layer.

In the invention, the metal mesh in the metal mesh layer is connected to the metal substrate through sintering, so that the metal mesh-metal substrate composite plate is obtained. The metal mesh (e.g., copper mesh) and the metal substrate (e.g., steel sheet) may be laminated, for example, by laying the metal mesh (e.g., copper mesh) on the metal substrate (e.g., steel sheet), and then sintering the metal mesh (e.g., copper mesh) and the metal substrate into a unitary body to obtain a metal mesh-metal substrate composite sheet (e.g., copper mesh-steel sheet composite sheet). Sintering may be performed in a sintering furnace. The sintering temperature may be 800-1000 deg.C, such as 900 + -50 deg.C, 900 + -20 deg.C. The sintering time may be 10-30 minutes, for example 15 + -5 minutes, 15 + -2 minutes. The sintering process is preferably protected by a mixed gas of an inert gas and a reducing gas (for example, a nitrogen-hydrogen mixed gas). In the mixed gas of the inert gas and the reducing gas, the volume ratio of the reducing gas (for example, hydrogen) to the inert gas (for example, nitrogen) is preferably 5: 1 to 2: 1, e.g., 3: about 1. In some embodiments, the invention lays a metal mesh (e.g. copper mesh) on a metal substrate (e.g. steel plate, preferably passivated steel plate), and puts the metal mesh into a sintering furnace to sinter into a whole, wherein the sintering is protected from oxidation by a mixed hydrogen-nitrogen atmosphere, the sintering temperature is 900 +/-20 ℃, and the sintering time is 15 +/-5 minutes. After sintering, a metallurgical bond is formed between the metal mesh and the metal substrate.

It can be understood that, in the PVDF composite board of the invention, the material of the sliding layer in the sliding layer is the same as the material of the sliding layer filled in the mesh of the metal mesh, and the sliding layer are integrally formed. Therefore, unless otherwise specified, the description of "sliding layer material" applies to both the sliding layer material in the sliding layer and the sliding layer material filled in the mesh of the metal mesh.

In the present invention, the sliding layer material includes or consists of PVDF, reinforcing fiber, and a solid lubricant. Herein, the sliding layer material is also referred to as a modified PVDF material. In the sliding layer material of the present invention, the content of PVDF is 65 to 85 wt%, the content of reinforcing fiber is 2 to 15 wt%, and the content of solid lubricant is 5 to 20 wt%. It is to be understood that in the present invention, for compositions containing two or more components, the sum of the weight percentages of all components in the composition should equal 100 wt%.

PVDF suitable for use in the present invention may be the FR906 type PVDF from Saneifu corporation. In the sliding layer material of the present invention, the content of PVDF may be 65 wt%, 70 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, 79 wt%, 80 wt%, 81 wt%, 82 wt%, 85 wt%, or in the range of any two of these contents.

The reinforcing fiber suitable for the present invention may be one or more selected from carbon fiber, glass fiber, potassium titanate whisker, calcium sulfate whisker and the like, and is preferably carbon fiber. The carbon fibers may have a filament diameter of 5 to 10 μm, for example 7. + -.1 μm, and a length of 70 to 150. mu.m, for example 80. + -.10 μm. The carbon fiber may be, for example, CM80-3.0/200-UN from SiGeri, Germany. The content of the reinforcing fiber in the sliding layer material of the present invention may be 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 10 wt%, 15 wt%, or within a range of any two of these contents. The addition of the reinforcing fibers helps to improve the bearing and wear resistance of the sliding layer material.

The solid lubricant suitable for use in the present invention may be a solid lubricant commonly used in the preparation of sliding materials, including but not limited to those selected from PTFE, graphite, MoS ₂ Carbon black, calcium fluoride, barium sulfate, silica, and the like. The content of the solid lubricant in the sliding layer material of the present invention may be 5 wt%, 10 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, or within a range of any two of these contents. In a preferred embodiment, the solid lubricant comprises or consists of PTFE and graphite. It is understood that the solid lubricant is usually in a powder form, and for example, PTFE and graphite as the solid lubricant are PTFE powder and graphite powder. The amount of PTFE in the sliding layer material of the present invention may be 6 wt%, 7 wt%, 8 wt%, 10 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt% or any two of these amountsWithin the range of (A) to (B). The content of graphite in the sliding layer material of the present invention may be 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, or within a range of any two of these contents.

The components of the sliding layer material and the proportion thereof are optimized and blended, so that the modified PVDF material has excellent self-lubricating property, wear resistance, ductility, noise resistance, anti-shaking property, running-in property and/or bearing capacity. In a preferred embodiment, the sliding layer material comprises: 75-82 wt.%, e.g. 77-80 wt.%, 79. + -.1 wt.% PVDF, 2-10 wt.%, e.g. 2-8 wt.%, 3. + -.1 wt.% reinforcing fibres, and 13-20 wt.%, e.g. 15-20 wt.%, 18. + -.2 wt.% solid lubricant. In a further preferred embodiment, the sliding layer material comprises: 75-82 wt.%, e.g., 77-80 wt.%, 79. + -. 1 wt.% PVDF, 2-10 wt.%, e.g., 2-8 wt.%, 3. + -. 1 wt.% carbon fibers, 6-18 wt.%, e.g., 8-16 wt.%, 15. + -. 1% PTFE, and 1-10 wt.%, e.g., 2-8 wt.%, 3. + -. 1% graphite, or a combination thereof.

In the present invention, the sliding layer material is prepared from the same resin composition as the sliding layer material. Therefore, in the present invention, the PVDF, the reinforcing fiber, the solid lubricant and the content thereof in the resin composition for preparing the sliding layer material may be the PVDF, the reinforcing fiber and the solid lubricant and the content thereof in the sliding layer material according to any of the embodiments described above, which are not described herein in detail. The resin composition of the present invention can improve the self-lubricity, wear resistance, ductility, noise resistance, anti-shudder, running-in and/or load-carrying capacity of the PVDF composite sheet. Accordingly, the present invention includes the use of a resin composition as described in any of the embodiments herein to improve the self-lubricity, wear resistance, ductility, noise resistance, anti-shudder, running-in, and/or load-bearing capacity of a PVDF composite sheet. Herein, the PVDF composite sheet refers to a composite material including a metal substrate and a resin composition, and the resin composition includes PVDF. The PVDF content in the resin composition contained in the PVDF composite sheet is preferably 30 wt% or more, for example, 40 wt% or more, 50 wt% or more, 60 wt% or more, and 65 wt% or more, based on the total weight of the resin composition. The PVDF composite sheet may include a metal substrate, an elastic layer, and a sliding layer. The sliding layer is composed of a resin composition. The resin composition in the sliding layer includes PVDF. The elastic layer is located between the metal substrate and the sliding layer. The elastic layer may include a metal mesh or a resin composition filled in the mesh of the metal mesh, or include metal powder and a resin composition. The resin composition in the elastic layer preferably includes PVDF, and is more preferably the same as the material of the sliding layer. The sliding layer may be integrally molded with the resin composition in the elastic layer, or separately molded. The resin composition, metal substrate, elastic layer, and sliding layer suitable for use in the PVDF composite sheet for the applications described herein may be as described in any of the embodiments herein. In some embodiments, the use comprises using the resin composition of any of the embodiments herein as a resin composition contained in a PVDF composite sheet.

The conventional method for preparing the PVDF sliding layer material is to put the uniformly mixed resin composition (mixture) into an extruder and extrude and granulate the resin composition (mixture) to obtain sliding layer material granules, then lay the granules on a metal powder metal substrate composite plate or a metal mesh metal substrate composite plate (such as a copper mesh steel plate composite plate) by a manual mode, heat the granules to melt the granules, and then roll the granules to obtain the composite plate. However, this method is not efficient because the blended PVDF has poor fluidity and spreadability, and the surface of the blended PVDF is textured.

The PVDF composite plate is obtained by uniformly mixing the components of the resin composition, putting the mixture into an extruder, directly extruding the mixture onto the surface of the metal mesh of the heated metal mesh metal substrate composite plate, and then rolling the metal mesh metal substrate composite plate loaded with the resin composition to form a sliding layer and a sliding layer material filled in meshes of the metal mesh. In the present invention, the extrusion temperature may be 210 ℃ to 230 ℃, for example, 225. + -. 5 ℃. The heating temperature of the metal mesh-metal substrate composite plate can be 210-225 ℃, for example, 220 +/-5 ℃. The manner of heating the expanded metal substrate composite panel may be induction heating. The rolling temperature may be 165-180 deg.C, for example 170 + -5 deg.C. The rolling pressure may be 60-100MPa, for example 80. + -.10 MPa. It will be appreciated that the amount of resin composition extruded onto the metal mesh metal substrate composite sheet is such that after rolling a sliding layer is formed on the side of the metal mesh not attached to the metal substrate and the mesh of the metal mesh is filled with the sliding layer material. The sliding layer of the PVDF composite board prepared by the method is thick, and the thickness can reach 0.08-0.2mm, such as 0.08-0.15mm and 0.1 +/-0.02 mm; the sliding layer has excellent compactness and good bearing resistance; the composite plate has the advantages that the binding force of the sliding layer and the metal mesh metal substrate composite plate is strong, so that the PVDF composite plate has good ductility and is not easy to delaminate and crack. The invention adopts the film coating process to prepare the sliding layer and the sliding layer material filled in the meshes of the metal mesh, thereby improving the self-lubricating property, the wear resistance, the ductility, the noise resistance, the shake resistance, the running-in property and/or the bearing capacity of the PVDF composite board.

The surface of the PVDF composite board has a micropore structure. Herein, the microporous structure (also called surface texture) refers to the surface micro-modeling, i.e. the lattice of pits or micro-grooves with certain shape and distribution on the surface of the material. Exemplary surface appearances of the PVDF composite sheets are shown in fig. 2(a) and 3(a), and exemplary microporous structures are shown in fig. 2(B) and 3 (B). The microporous structure on the surface of the PVDF composite board has the effects of improving the lubricating and friction properties of the material and prolonging the service life of the material, and can be used as an oil storage tank to provide lubrication for the boundary lubricating or composite lubricating surface, generate pressure dynamic lubrication on the parallel surfaces and reduce the friction factor.

In some embodiments, the PVDF composite sheet of the invention is prepared by a method comprising the steps of:

(1) and paving the copper mesh on the passivated steel plate, and putting the passivated steel plate into a sintering furnace to be sintered into a whole to obtain the copper mesh steel plate composite plate, wherein the sintering temperature is 800-1000 ℃, such as 900 +/-50 ℃ and 900 +/-20 ℃, the sintering time is 10-30 minutes, such as 15 +/-5 minutes and 15 +/-2 minutes, and the volume ratio is 5: 1 to 2: 1. for example, 3: a mixed gas (for example, a hydrogen-nitrogen mixed atmosphere) of about 1 of a reducing gas and an inert gas;

(2) the components of the resin composition are uniformly mixed to obtain a mixture, the mixture is put into an extruder and extruded to the surface of a copper net of a heated copper net steel plate composite plate, and the heated copper net is rolled to obtain the PVDF composite plate, wherein the extrusion temperature is 210-230 ℃, such as 225 +/-5 ℃, the heating temperature of the copper net steel plate composite plate is 210-225 ℃, such as 220 +/-5 ℃, the heating mode of the metal net metal substrate composite plate is preferably induction heating, the rolling temperature is 165-180 ℃, such as 170 +/-5 ℃, and the rolling pressure is 60-100MPa, such as 80 +/-10 MPa.

The sliding layer material in the PVDF composite board is directly discharged by an extruder and is formed by rolling, and the PVDF composite board is compact in material and suitable for flow line production.

The PVDF composite board has excellent self-lubricating property and wear resistance. The PVDF composite sheet material of the invention has a coefficient of friction of 0.027 or less, for example 0.026, 0.025 or less, 0.024 or less, 0.023 or less, 0.022 or less, 0.021 or less, after 8 hours of testing under conditions of a specimen size of phi 42 x phi 40 x 30mm, a load of 60MP, a speed of 1.5m/min, lubrication conditions of 3 lithium-based greases, and a grinding member of 45 steel having a roughness Ra of 0.4 mu m. The PVDF composite sheet of the invention exhibits an amount of wear of 0.025mm or less, for example, preferably 0.022mm or less, 0.020mm or less, 0.019mm or less, 0.018mm or less, 0.017mm or less, 0.016mm or less, 0.015mm or less, 0.014mm or less, 0.013mm or less, 0.012mm or less, 0.011mm or less, 0.010mm or less, and 0.009mm or less after 8 hours of testing with a sample size of phi 42 x phi 40 x 30mm, a load of 60MP, a speed of 1.5m/min, a lubricating condition of 3 lithium-based grease, and a condition of 45 steel with a roughness Ra of 0.4 μm for the grinding member.

The invention also provides a preparation system of the composite board, which can be used for preparing the PVDF composite board or other composite boards with the metal substrate, the elastic layer (metal mesh layer) and the sliding layer (resin layer). The preparation system of the composite board can be used for extruding the resin composition to the surface of the metal mesh of the heated metal mesh metal substrate composite board and then rolling to obtain the composite board. The preparation system of the composite plate comprises a traction device, a heating device, an extruder and a rolling mill, wherein the traction device is used for drawing the metal mesh metal substrate composite plate to pass through the heating device and the rolling mill in sequence, the heating device is used for heating the metal mesh metal substrate composite plate, the extruder is used for extruding the resin composition to the surface of the metal mesh metal substrate composite plate between the heating device and the rolling mill, the extruder comprises a feed opening and a discharge opening, the discharge opening of the extruder is arranged between the heating device and the rolling mill, and the rolling mill is used for rolling the metal mesh metal substrate composite plate loaded with the resin composition.

The heating device suitable for the invention is preferably an induction heating furnace, and can be used for carrying out induction heating on the metal mesh and metal substrate composite plate. The heating device includes an inlet and an outlet. The pulling device is typically arranged at an end of the preparation system of the invention, for example at the head (i.e. foremost) and/or the tail (i.e. end) of the preparation system. The preparation system of the present invention may comprise one or more pulling devices. The extruder suitable for the present invention may be various extruders capable of mixing, plasticizing and extruding the raw materials of the resin composition, such as a screw extruder. The extruder is provided with a feed opening (also called a feed opening and a feed opening) and a discharge opening. In the present invention, the discharge port of the extruder is disposed between the heating device and the rolling mill, so that the extruder extrudes the resin composition directly onto the metal mesh surface of the metal mesh metal substrate composite plate located between the heating device and the rolling mill. The discharge port of the extruder is preferably close to the roll inlet of the rolling mill, particularly the rolling mill, so that the resin composition extruded onto the metal composite plate maintains good plasticity when subjected to rolling. Rolling mills are also known as calenders and roll presses. The rolling mill suitable for the present invention may be any of various rolling mills capable of rolling a plate. A rolling mill typically includes a roll, a stand, a roll gap adjustment device, a roll temperature adjustment device, a transmission, a lubrication system, and a control system. The rolling mill includes an inlet and an outlet. According to the invention, the inlet of the rolling mill is aligned with the outlet of the heating device, so that the metal mesh and metal substrate composite plate coming out of the heating device can smoothly enter the rolling mill.

The traction device typically includes a driving device and/or a guiding device for driving the movement of the metal-based composite plate and controlling the direction of movement of the metal-based composite plate, respectively. The driving device may include an unreeling machine and a reeling machine, which are respectively used for unreeling the metal substrate composite plate and reeling the composite plate, and are respectively arranged at the upstream of the heating device (such as the head of the preparation system) and the downstream of the rolling mill (such as the tail of the preparation system). Here, upstream and downstream are relative to the direction of movement of the sheet. The guide means may comprise one or more pairs of guide rollers. When guide rollers are used as the guide means, at least one pair of guide rollers is usually provided upstream of the heating means, for example, between the heating means and a driving means (e.g., an unreeling machine), to control the orientation of the sheet material when it enters the heating means. The guide rollers can be arranged on a support device, for example on a frame or frame structure that serves for fixing purposes. Induction furnaces, unwinders, winders and guide rolls suitable for use in the present invention may be conventional in the art.

The preparation system of the present invention may further comprise a conveying device and/or a supporting device. The conveying device is used for supporting the metal composite plate and the composite plate formed after rolling. The transfer device may be in communication with the pulling device upstream of the heating device, the rolling mill, and/or the pulling device downstream of the rolling mill. The support device is used for supporting, connecting and/or fixing other devices. The pulling device, the heating device, the extruder, the rolling mill and/or the conveying device may be interconnected by a support device. The arrangement of the conveying means and the supporting means may be conventional. For example, the conveyor may be a conveyor belt, which may pass through the heating device and the rolling mill. The support means may be a stand, etc., for example the support means may be a base connecting the traction means (e.g. winder, guide roll and unwinder), the heating means and the rolling mill.

FIG. 4 shows a schematic structural view of one embodiment of the production system of the present invention. The preparation system comprises an unreeling machine, a guide roller, an induction heating rate, an extruder, a rolling mill and a reeling machine. The unreeling machine and the reeling machine are respectively positioned at the head and the tail of the preparation system and are used for drawing the steel strip copper mesh composite plate to pass through the induction heating furnace and the rolling mill in sequence. A pair of guide rollers is arranged between the induction heating furnace and the unreeling machine and used for controlling the direction of the steel strip copper mesh composite board when entering the induction heating furnace. The guide rollers are arranged on a frame structure which plays a role in fixing. The induction heating furnace is used for heating the steel strip copper mesh composite board. The extruder is used to extrude the resin composition onto the surface of the metal mesh of the steel strip-copper mesh composite sheet located between the induction heating furnace and the rolling mill. The extruder comprises a feed opening and a discharge opening, and the discharge opening of the extruder is arranged between the induction heating furnace and the rolling mill and close to a roller of the rolling mill. The rolling mill is used for rolling the steel strip copper mesh composite plate loaded with the resin composition. The manufacturing system may also include a conveyor in communication with the unreeling machine, the guide roll, the induction heating furnace, the rolling mill, and/or the reeling machine. The preparation system also comprises a base connected with the unreeling machine, the guide roll, the induction heating furnace, the rolling mill and the reeling machine.

The PVDF composite board can be applied to axles, brakes, air compressors, seat angle adjusters, suspension systems and the like of trucks or commercial vehicles, hydraulic elements such as plunger pumps, hydraulic motors, rotary motors and the like, and common industrial sliding bearings such as agricultural machinery, forest machinery, logistics equipment and the like, in particular to rack support bearing bushes of automobile steering gears.

The invention also provides an automobile steering gear rack support bearing bush made of the PVDF composite board. The automotive steering gear rack support bushing of the present invention has the appearance of an automotive steering gear rack support bushing as is conventional in the art. As shown in fig. 1, the rack support bushing for an automobile steering gear is generally a thin plate bent in an arc shape, and the middle portion of the thin plate has a boss protruding toward the outer side of the arc shape.

The invention also provides an automobile steering gear rack supporting device which comprises the automobile steering gear rack supporting bearing bush and the supporting seat. As shown in fig. 1, the supporting seat has a cylindrical shape with one end having a concave arc surface, a bearing bush mounting hole matched with the boss of the bearing bush is formed in the middle of the concave arc surface for mounting the bearing bush, and the shape of the bearing bush is matched with the property of the concave arc surface of the supporting seat.

The PVDF composite board has the following advantages:

1. the PVDF composite board has good wear resistance; 2. the surface hardness of the PVDF composite board is higher than that of the PTFE composite material prepared by the traditional wet fluorine method, and the PTFE composite material prepared by the traditional wet fluorine method is loose due to the addition of the aqueous solvent; the PVDF composite board has higher bearing resistance; 3. the sliding layer of the PVDF composite board can be more than 0.1mm and even higher, does not bubble, and can adapt to a larger range of fit clearance; 4. the metal mesh layer (such as a copper mesh layer) of the PVDF composite board has the function of an elastic layer, and has the effects of reducing noise and preventing shaking; 5. according to the PVDF composite board, the surface of the modified PVDF material is provided with a microporous structure after being combined with the copper mesh, so that grease is easy to store and is suitable for grease lubrication; 6. the invention preferably uses the resin composition with the improved formula for manufacturing the sliding layer material, and simultaneously adopts the film coating process (namely, the sliding layer material is directly extruded to a preheated metal mesh metal substrate composite plate by an extruder and then rolled) to prepare the PVDF composite plate, the improved formula and the improved process have a synergistic effect, so that the self-lubricating property, the wear resistance, the ductility, the bearing resistance, the running-in property, the noise resistance and the anti-shaking property of the material can be further obviously improved.

The present invention is further illustrated by the following specific examples. The scope of the present invention is not limited by the contents of the following examples. The scope of the present invention is defined only by the appended claims, and any omissions, substitutions, and changes in the form of the embodiments disclosed herein that may be made by those skilled in the art will fall within the scope of the present invention.

The following examples and comparative examples use equipment conventional in the art. The experimental methods and the detection methods, in which specific conditions are not noted in the following examples and comparative examples, are generally performed according to conventional conditions or according to conditions recommended by manufacturers. The various starting materials used in the following examples and comparative examples, unless otherwise specified, were conventional commercially available products. In the description of the present invention and the following examples and comparative examples, "%" represents weight percent, "parts" represents parts by weight, and ratios represent weight ratios, unless otherwise specified.

The raw materials used in the examples and comparative examples are illustrated below: (1) PVDF: FR906 of sainfu corporation; (2) carbon fiber: CM80-3.0/200-UN (filament diameter 7 μm, length 80 μm) from Sigli, Germany; (3) solid lubricant: commercially available graphite powder, PTFE fine powder, MoS ₂ Pulverizing; (4) copper mesh: QSn6.5-0.1 copper alloy mesh; (5) steel plate: SPCC cold rolled steel sheets; (6) copper powder: QQSn 8-3 is used for atomizing spherical copper powder; (7) polyphenyl ester: zhonghao cheng light Ekonol; (8) PTFE suspension powder: DF-102 suspension powder in east Shandong Yue; (9) PTFE dispersion: the sky is morning light SFN-1.

Example 1

The formulation of the resin composition of this example was: 79 wt% PVDF, 3 wt% carbon fiber, 15 wt% PTFE fine powder, 3 wt% graphite powder.

The PVDF composite board is prepared by adopting the following process in the embodiment:

(1) and (2) laying a copper mesh on a passivated steel plate, wherein the copper mesh is woven, the wire diameter of the copper mesh is 0.25mm, the mesh number of the copper mesh is 40 meshes, and the copper mesh is put into a sintering furnace to be sintered into a whole to obtain the copper mesh steel plate composite plate, wherein the sintering temperature is 900 ℃, the sintering time is 15 minutes, and the volume ratio is 3: 1, protecting hydrogen and nitrogen mixed atmosphere;

(2) mixing the components of the resin composition to obtain a mixture; and (2) putting the mixture into an extruder to be directly extruded to the surface of the copper mesh of the steel belt copper mesh composite plate subjected to induction heating, and rolling to obtain the PVDF composite plate, wherein the extrusion temperature is 225 ℃, the induction heating temperature of the steel belt copper mesh composite plate is 220 ℃, the rolling temperature is 170 ℃, the rolling pressure is 80MPa, and the thickness of the rolled resin layer is 0.1 mm.

Example 2

The formulation of the resin composition of this example was: 80 wt% of PVDF, 5 wt% of carbon fiber, 10 wt% of PTFE fine powder and 5 wt% of graphite powder.

Example 3

The formulation of the resin composition of this example was: 77 wt% of PVDF, 7 wt% of carbon fiber, 8 wt% of PTFE fine powder and 8 wt% of graphite powder.

(1) laying a copper net on a passivated steel plate, wherein the copper net is a woven copper net, the wire diameter of the copper net is 0.25mm, the mesh number of the copper net is 40 meshes, putting the copper net into a sintering furnace, sintering the copper net and the copper net into a whole to obtain the copper net and steel plate composite plate, wherein the sintering temperature is 900 ℃, the sintering time is 15 minutes, and the volume ratio is 3 in the sintering process: 1, protecting hydrogen and nitrogen mixed atmosphere;

Example 4

(1) laying a copper net on a passivated steel plate, wherein the copper net is a woven copper net, the wire diameter of the copper net is 0.15mm, the mesh number of the copper net is 40 meshes, putting the copper net into a sintering furnace, sintering the copper net and the copper net into a whole to obtain the copper net and steel plate composite plate, wherein the sintering temperature is 900 ℃, the sintering time is 15 minutes, and the volume ratio is 3 in the sintering process: 1, protecting hydrogen and nitrogen mixed atmosphere;

Example 5

(1) laying a copper mesh on a passivated steel plate, wherein the copper mesh is a punched and stretched copper mesh, the wire diameter of the copper mesh is 0.3mm, the length sizes of diagonals of diamond-shaped holes of the copper mesh are 950mm and 650mm respectively, and the copper mesh and the diamond-shaped holes are placed into a sintering furnace to be sintered into a whole to obtain a copper mesh and steel plate composite plate, wherein the sintering temperature is 900 ℃, the sintering time is 15 minutes, and the volume ratio is 3 in the sintering process: 1, protecting hydrogen and nitrogen mixed atmosphere;

Comparative example 1: PVDF composite board prepared by copper powder steel plate composite board and traditional manual laying method

The formulation of the resin composition of this comparative example was: 85 wt% of PVDF, 10 wt% of carbon fiber and 5 wt% of graphite powder.

The PVDF composite board is prepared by adopting the following process in the comparative example:

(1) copper powder is laid on a passivated steel plate, the laying thickness of the copper powder is 0.35mm, the copper powder is placed into a sintering furnace to be sintered, the sintering temperature is 850 ℃, and the volume ratio in the sintering process is 3: 1, sintering, rolling until the thickness of a copper powder layer is 0.25mm, and preparing a copper powder steel plate composite plate;

(2) mixing the components of the resin composition to obtain a mixture; putting the mixture into an extruder for extrusion granulation, manually paving the granules on the surface of the copper powder layer of the copper powder steel plate composite plate, wherein the extrusion granulation temperature is 225 ℃,

(3) heating the copper powder steel plate composite plate loaded with the granules to 260 ℃ or above to melt the granules, and then rolling to obtain the PVDF composite plate, wherein the rolling mill is at normal temperature and is not heated, and the thickness of the rolled resin layer is 0.1 mm.

Comparative example 2: PTFE composite board prepared by adopting traditional wet fluorine process

The formulation of the resin composition of this comparative example was: 70 wt% of PTFE suspension powder, 20 wt% of polyphenyl ester and 10 wt% of MoS ₂ And (3) pulverizing. The PTFE dispersion liquid is: the sky is morning light SFN-1.

The PTFE composite board is prepared by adopting the following process in the comparative example:

(2) mixing the components of the resin composition uniformly to obtain a mixture; mixing the mixture and PTFE dispersion liquid (mass ratio is 4: 1) to form slurry, laying the slurry on a copper net layer, performing cold rolling, wherein the thickness of the slurry on the copper net layer after rolling is about 0.8mm, and drying after rolling at the drying temperature of 310 ℃ for 20 min; and (2) sintering the dried plate in a nitrogen furnace at 395 ℃ for 90min, wherein the volume ratio of the sintered plate to the sintered plate is 3: 1, and performing finish rolling and leveling on the sintered plate under the protection of a hydrogen-nitrogen mixed atmosphere, wherein the thickness of the rolled resin layer is 0.03 mm.

Comparative example 3: PVDF composite board prepared by adopting copper mesh steel plate composite board and traditional manual laying method

The formulation of the resin composition of this example was: 79 wt% PVDF, 3 wt% carbon fiber, 15 wt% PTFE fine powder, 3 wt% graphite.

The PVDF composite board is prepared by adopting the following process:

(1) laying a copper net on a passivated steel plate, wherein the copper net is a woven copper net, the wire diameter of the copper net is 0.25mm, the mesh number of the copper net is 40 meshes, putting the copper net into a sintering furnace, sintering the copper net and the copper net into a whole to obtain the copper net and steel plate composite plate, wherein the sintering temperature is 900 ℃, the sintering time is 15 minutes, and the volume ratio is 3: 1, protecting hydrogen and nitrogen mixed atmosphere;

(2) mixing the components of the resin composition to obtain a mixture; putting the mixture into an extruder for extrusion granulation, and manually paving granules on the surface of a copper mesh layer of the copper mesh steel plate composite board, wherein the extrusion granulation temperature is 225 ℃;

(3) heating the copper mesh steel plate composite plate loaded with the granules to 260 ℃ or above to melt the granules, and then rolling to obtain the PVDF composite plate, wherein the rolling mill is at normal temperature and is not heated, and the thickness of the rolled resin layer is 0.1 mm.

Comparative example 4

The formulation of the resin composition of this example was: 85 wt% of PVDF, 10 wt% of carbon fiber and 5 wt% of graphite powder.

The PVDF composite board is prepared by adopting the following process:

Test example 1: rocking friction test

The plates prepared in the examples and comparative examples were examined for frictional wear properties using a home-made rocking friction tester (model: YBJ-C-18).

And (3) testing conditions are as follows: test piece size: phi 42 is multiplied by phi 40 is multiplied by 30 mm; and (3) grinding a part: 45# steel, hardness 43-47 HRC, Ra 0.4 μm; loading: 60 MPa; speed: 1.5 m/min; lubrication conditions: 3# lithium-based grease; and (3) testing time: 8 hours; the counter-grinding form of the trial piece and the counter-grinding piece is shown in fig. 5.

The results of the rocking friction test are shown in table 1.

Table 1: results of the rocking friction test of the sheets of examples and comparative examples

	Coefficient of friction	Abrasion loss (mm)
			Example 1	0.021	0.009
Example 2	0.022	0.011
			Example 3	0.023	0.013
Example 4	0.022	0.010
			Example 5	0.022	0.011
Comparative example 1	0.030	0.035
			Comparative example 2	0.037	0.049
Comparative example 3	0.026	0.020
			Comparative example 4	0.025	0.018

As can be seen from Table 1, the PVDF composite sheets of examples 1-5, which had very low coefficients of friction and wear, demonstrated excellent self-lubricity and wear resistance, were optimized for the formulation and process of example 1, with the best performance. The friction coefficient and the abrasion loss of the PVDF composite plate prepared by the conventional process and the copper powder steel plate in the comparative example 1 and the PTFE composite plate prepared by the wet fluorine method in the comparative example 2 are obviously higher than those of the examples 1-5, which shows that the self-lubricating property and the abrasion resistance of the PVDF composite plate and the PTFE composite plate are poor.

The friction coefficient and the wear rate of the PVDF composite board of the comparative example 3 are higher than those of the PVDF composite board of the example 1, which shows that the film coating process is beneficial to improving the self-lubricating property and the wear resistance of the PVDF composite board. The PVDF composite board of the comparative example 4 has higher friction coefficient and higher abrasion loss than those of the examples 1-5, which shows that the resin composition formulas (PVDF + carbon fiber + PTFE powder + graphite powder) of the examples 1-5 are beneficial to improving the self-lubricating property and the abrasion resistance of the PVDF composite board.

Test example 2: bending test

The ductility of the sheets prepared in the examples and comparative examples was examined by bending test.

Sample size: 120mm 20mm 1 mm. The test device comprises: as shown in fig. 6. The test method comprises the following steps: and (3) clamping the test sample, bending the test sample towards the plastic surface at 60 degrees, and then bending the test sample towards the steel back at 60 degrees for one time, and repeating the steps for 5 times, wherein the test sample is observed for whether the test sample cracks and delaminates every time.

The bending test results are shown in table 2. The appearance of the PVDF composite sheet samples of example 1 and comparative example 4 after the bending test is shown in fig. 7 and fig. 8, respectively.

Table 2: bending test results of the sheets of examples and comparative examples

	Status of state
		Example 1	No delaminating and cracking and good extensibility
Example 2	No delaminating and cracking and good extensibility
		Example 3	No delaminating and cracking and good extensibility
Example 4	No delaminating and cracking and good extensibility
		Example 5	No delaminating and cracking and good extensibility
Comparative example 1	Cracking of
		Comparative example 2	Cracking of
Comparative example 3	Slight crack
		Comparative example 4	Slight crack

As is clear from Table 2, the PVDF composite sheets of examples 1 to 5 had excellent elongation without cracking and delamination. The PVDF composite sheet of comparative example 1 and the PTFE composite sheet of comparative example 2 cracked significantly and were poor in extensibility.

The PVDF composite sheet of comparative example 3 was slightly cracked, while the PVDF composite sheet of example 1 was free from cracking and delamination, indicating that the lamination process of the present invention is advantageous in improving the ductility of the PVDF composite sheet. The PVDF composite sheet of comparative example 4 slightly cracked, while the PVDF composite sheets of examples 1-5 did not crack and delaminate, indicating that the resin composition formulations of examples 1-5 (PVDF + carbon fiber + PTFE powder + graphite powder) are advantageous in improving the ductility of the PVDF composite sheet.

Test example 3: bench test

The plates of examples and comparative examples were prepared into bearing bushes, and noise, vibration and wear were examined using bench tests using a home-made steering gear supported bush friction tester as shown in fig. 9.

Shape and size of bearing bush for test: as shown in fig. 10. The test conditions are as follows: the times are as follows: 15000 times; loading: 8000N; amplitude of reciprocating motion: plus or minus 250 mm; speed: 0.064 m/s; test time: 32 h; lubrication conditions: coating grease for one time; test temperature: room temperature; and (3) shaft grinding: 37CrS4, the hardness after quenching is HV 780-930,

the roughness is less than or equal to Ra0.8.

The results of the bench test are shown in table 3 and fig. 11.

Table 3: bench test results of the sheets of examples and comparative examples

	Description of the test procedure	Abrasion loss (mm)
			Example 1	The test is stable, and no noise or jitter is generated in the test process	0.02
Example 2	The test is stable, and no noise or jitter is generated in the test process	0.03
			Example 3	The test is stable, and no noise or jitter is generated in the test process	0.05
Example 4	The test is stable, and no noise or jitter is generated in the test process	0.04
			Example 5	The test is stable, and no noise or jitter is generated in the test process	0.04
Comparative example 1	Noise and jitter are generated in the test process	0.10
			Comparative example 2	Noise and jitter are generated in the test process	0.15
Comparative example 3	Noise and jitter are generated in the test process	0.08
			Comparative example 4	Noise and jitter are generated in the test process	0.10

As can be seen from Table 3 and FIG. 11, the bearing shells made from the plates of examples 1-5 were free from noise and vibration during the test, indicating that they have good noise-damping characteristics and running-in properties, low wear, and excellent wear resistance and load-bearing capacity. The bearing bush made of the plate of comparative example 1 was noisy and shaky and exhibited some wear. The bush made of the plate of comparative example 2 was noisy and shaky and was worn heavily.

The bearing bush made of the plate of the comparative example 3 has noise and vibration and generates certain abrasion, while the bearing bush made of the plate of the example 1 has no noise and vibration and small abrasion, which shows that the film coating process of the invention is beneficial to improving the noise resistance, vibration resistance, running-in property, stability, abrasion resistance and bearing capacity of the PVDF composite plate. The bearing bushes made from the sheet material of comparative example 4 were noisy and shaky and experienced some wear, while the bearing bushes made from the sheet materials of examples 1-5 were quiet and shaky and experienced very little wear, indicating that the resin composition formulations (PVDF + carbon fiber + PTFE powder + graphite powder) of examples 1-5 are beneficial for improving the noise, shaky, running, stability, wear resistance and load-bearing capacity of the PVDF composite sheet materials.

Claims

1. A PVDF composite sheet, comprising a metal substrate, an elastic layer and a sliding layer, wherein the elastic layer is located between the metal substrate and the sliding layer, the elastic layer comprises a metal mesh and a sliding layer material filled in meshes of the metal mesh, the metal mesh is connected to the metal substrate by sintering, the sliding layer and the sliding layer material filled in the meshes of the metal mesh are formed by rolling a resin composition extruded on the surface of the metal mesh, the resin composition comprises PVDF, a reinforcing fiber and a solid lubricant, and the content of PVDF, the content of the reinforcing fiber and the solid lubricant in the resin composition are 65-85 wt%, 2-15 wt% and 5-20 wt%, respectively, based on the total weight of the resin composition.

2. The PVDF composite sheet of claim 1, wherein the PVDF composite sheet has one or more of the following characteristics:

(1) the metal substrate is a steel plate;

(2) the metal net is a copper net, the diameter of the copper net is preferably 0.1-0.35mm, and the mesh number of the copper net is preferably 40 +/-10 meshes;

(3) the thickness of the sliding layer is 0.08-0.2 mm;

(4) based on the total weight of the resin composition, the content of PVDF is 75-82 wt%, the content of reinforcing fiber is 2-10 wt%, and the content of solid lubricant is 13-20 wt%;

(5) the reinforcing fiber is selected from one or more of carbon fiber, glass fiber, potassium titanate whisker and calcium sulfate whisker, preferably carbon fiber, the monofilament diameter of the carbon fiber is preferably 5-10 μm, and the length of the carbon fiber is preferably 70-150 μm;

(6) the solid lubricantThe agent is selected from PTFE, graphite, MoS ₂ One or more of carbon black, calcium fluoride, barium sulfate and silica, preferably including PTFE and graphite; preferably, the resin composition contains PTFE in an amount of 6 to 18 wt%, preferably 8 to 16 wt%, and graphite in an amount of 1 to 10 wt%, preferably 2 to 8 wt%, based on the total weight of the resin composition;

(7) the friction coefficient of the PVDF composite plate after being tested for 8 hours under the conditions that a sample size is phi 42 multiplied by phi 40 multiplied by 30mm, the load is 60MP, the speed is 1.5m/min, the lubricating condition is No. 3 lithium-based grease, and a grinding piece is No. 45 steel with the roughness Ra of 0.4 mu m is less than or equal to 0.027, preferably less than or equal to 0.026, more preferably less than or equal to 0.025, and more preferably less than or equal to 0.024; and

(8) the PVDF composite board has the abrasion loss after being tested for 8 hours under the conditions that a sample size is phi 42 multiplied by phi 40 multiplied by 30mm, the load is 60MP, the speed is 1.5m/min, the lubricating condition is No. 3 lithium-based grease, and a grinding piece is No. 45 steel with the roughness Ra of 0.4 mu m, wherein the abrasion loss is less than or equal to 0.025mm, preferably less than or equal to 0.020mm, more preferably less than or equal to 0.018mm and more preferably less than or equal to 0.015 mm.

3. The PVDF composite sheet according to claim 1, wherein the resin composition comprises PVDF, carbon fiber, PTFE and graphite, and wherein PVDF is contained in an amount of 65 to 85 wt%, preferably 75 to 82 wt%, reinforcing fiber is contained in an amount of 2 to 15 wt%, preferably 2 to 10 wt%, PTFE is contained in an amount of 6 to 18 wt%, preferably 8 to 16 wt%, and graphite is contained in an amount of 1 to 10 wt%, preferably 2 to 8 wt%, based on the total weight of the resin composition.

4. A method of making a PVDF composite sheet, the method comprising: extruding a resin composition onto the surface of a metal mesh of a heated metal mesh metal substrate composite plate, and then rolling, wherein the metal mesh metal substrate composite plate is formed by sintering the metal mesh and a metal substrate, the resin composition comprises PVDF, reinforcing fibers and a solid lubricant, and based on the total weight of the resin composition, the content of PVDF in the resin composition is 65-85 wt%, the content of reinforcing fibers is 2-15 wt%, and the content of the solid lubricant is 5-20 wt%.

5. The method of claim 4, wherein the method has one or more of the following features:

(1) the metal substrate is a steel plate;

(2) the metal net is a copper net, the wire diameter of the copper net is preferably 0.1-0.35mm, and the mesh number of the copper net is preferably 40 +/-10 meshes;

(3) the thickness of the sliding layer is 0.08-0.2 mm;

(6) the solid lubricant is selected from PTFE, graphite and MoS ₂ One or more of carbon black, calcium fluoride, barium sulfate and silica, preferably including PTFE and graphite; preferably, the resin composition contains PTFE in an amount of 6 to 18 wt%, preferably 8 to 16 wt%, and graphite in an amount of 1 to 10 wt%, preferably 2 to 8 wt%, based on the total weight of the resin composition;

(7) the extrusion temperature of the resin composition is 210-230 ℃, preferably 225 +/-5 ℃;

(8) the heating temperature of the metal mesh metal substrate composite plate is 210-225 ℃, and preferably 220 +/-5 ℃;

(9) the heating mode of the metal mesh and metal substrate composite plate is induction heating;

(10) the rolling temperature is 165-180 ℃, preferably 170 +/-5 ℃, and the rolling pressure is 60-100MPa, preferably 80 +/-10 MPa; and

(11) the sintering temperature for sintering the metal mesh and the metal substrate is 800-1000 ℃, preferably 900 +/-50 ℃, the sintering time is 10-30 minutes, preferably 15 +/-5 minutes, a mixed gas of reducing gas and inert gas, such as hydrogen-nitrogen mixed gas, is used for protection during the sintering process, and the volume ratio of the reducing gas to the inert gas is preferably 5: 1 to 2: 1.

6. the PVDF composite board prepared by the method of claim 4 or 5.

7. A production system for producing the PVDF composite sheet material as defined in any one of claims 1-3 and 6, wherein the production system comprises an unreeling machine, a guide roll, an induction heating furnace, an extruder, a rolling mill and a reeling machine, wherein the unreeling machine is used for unreeling the metal mesh metal substrate composite sheet, the guide roll is arranged at the downstream of the unreeling machine and is used for controlling the movement direction of the metal mesh metal substrate composite sheet, the induction heating furnace is arranged at the downstream of the guide roll and is used for heating the metal mesh metal substrate composite sheet, a discharge port of the extruder is arranged between the induction heating furnace and the rolling mill and is used for extruding the resin composition onto the metal mesh surface of the metal mesh metal substrate composite sheet arranged between the induction heating furnace and the rolling mill, and the rolling mill is arranged at the downstream of the induction heating furnace, The rolling machine is used for rolling the metal mesh metal substrate composite plate loaded with the resin composition, and the rolling machine is arranged at the downstream of the rolling machine and used for rolling the PVDF composite plate.

8. The resin composition is characterized by comprising 65-85 wt% of PVDF, 2-15 wt% of reinforcing fiber, 6-18 wt% of PTFE and 1-10 wt% of graphite, based on the total weight of the resin composition;

preferably, the resin composition contains 75-82 wt% of PVDF, 2-10 wt% of reinforcing fiber, 8-16 wt% of PTFE and 2-8 wt% of graphite, based on the total weight of the resin composition;

preferably, the monofilament diameter of the carbon fiber is preferably 5 to 10 μm, and the length of the carbon fiber is preferably 70 to 150 μm.

9. Use of the resin composition of claim 8 to improve the self-lubricity, wear resistance, ductility, noise resistance, anti-shudder, running-in, and/or load-bearing capacity of PVDF composite sheets.

10. A sliding member made of the PVDF composite sheet described in any one of claims 1 to 3 and 6 or a sliding device containing a sliding member made of the PVDF composite sheet described in any one of claims 1 to 3 and 6; preferably, the sliding part is a bushing, a washer or a shim plate, preferably an automotive steering gear rack support bushing; preferably, the sliding device is a sliding bearing, an axle, a brake, an air compressor, a seat adjuster, a suspension system or a hydraulic element, preferably a steering rack support device of an automobile.