Super-oil-absorption PTFE (Polytetrafluoroethylene) fiber material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of functional fiber lubricating materials, and particularly relates to a super-oil-absorption PTFE fiber material and a preparation method and application thereof. The super-oil-absorption PTFE fiber material comprises a PTFE fiber composite fabric, a bonding layer, a metal organic framework material and a liquid lubricating oil agent adsorbed in a pore structure of the metal organic framework material, the bonding layer is a copolymer of polyphenol substances and polyethyleneimine; the bonding layer is connected to PTFE fibers on one side of the PTFE fiber composite fabric through hydrogen bonds; the metal organic framework material is connected to the bonding layer through an ester bond. The application of the super-oil-absorption PTFE fiber material can effectively improve the friction characteristic of the fabric self-lubricating liner, so that the fabric self-lubricating liner has excellent lubricating performance and wear resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional fiber lubricating materials, and particularly relates to a super oil-absorbing PTFE fiber material, a preparation method thereof, and an application thereof. Background Art

[0002] As a spherical sliding bearing, a self-lubricating spherical plain bearing mainly consists of an outer ring with an inner spherical surface, an inner ring with an outer spherical surface, and a self-lubricating gasket. The self-lubricating gasket is bonded to the inner side of the bearing outer ring, and its self-lubricating property ensures that the friction between the inner and outer ring metals is effectively reduced during the operation of the bearing, thereby ensuring the stable transmission and precise control of precision bearing equipment.

[0003] Fabric-based self-lubricating materials have the advantages of strong load-bearing capacity, pollution resistance, and maintenance-free, and have been widely used in the bushings of spherical plain bearings, showing great application potential in the aerospace, shipbuilding, and weaponry industries. Fabric-based self-lubricating gaskets are generally made by weaving polytetrafluoroethylene (PTFE) fibers and other high-performance fibers (such as basalt fibers) into a fabric, and then impregnating the fabric with resin and hot-pressing it into shape. Among them, PTFE fibers undertake the lubricating function, and other high-performance fibers undertake the mechanical function.

[0004] However, the self-lubricating mechanism of PTFE fibers is single, and it cannot provide stable lubricating performance for self-lubricating gasket materials. When the bearing operates under low-quality lubrication conditions for a long time, it will cause energy loss and heat generation of the components, reduce the stability and reliability of the machine, and greatly shorten the service life of the spherical plain bearing.

[0005] Currently, the main way to improve the lubricating performance of self-lubricating materials is to fill microcapsules containing lubricants as fillers into the resin matrix of the composite material. For example, paraffin and polyalpha olefins and other lubricating oils are encapsulated with shell materials such as SiO2 and polystyrene as microcapsules. However, the filling of fillers will cause particle agglomeration, reduce the homogeneity of the resin material, and thus lead to a significant reduction in the mechanical properties of the self-lubricating gasket material, resulting in poor wear resistance of the self-lubricating gasket material. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a super oil-absorbing PTFE fiber material, a preparation method thereof, and an application thereof. The self-lubricating gasket prepared by using the super oil-absorbing PTFE fiber material has excellent lubricating performance and wear resistance.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] The present invention provides a super oil-absorbing PTFE fiber material, which includes a PTFE fiber composite fabric, a bonding layer, a metal-organic framework material, and a liquid lubricant adsorbed in the pore structure of the metal-organic framework material; the bonding layer is a copolymer of a polyphenol substance and polyethyleneimine; the bonding layer is connected to the PTFE fibers on one side of the PTFE fiber composite fabric through hydrogen bonds; the metal-organic framework material is connected to the bonding layer through an ester bond.

[0009] Preferably, the PTFE fiber composite fabric has a 1 / 3 twill weave structure; the areal density of the PTFE fiber composite fabric is 300 - 400 g / m 2 , the warp density is 150 - 180 ends / 10 cm, and the weft density is 100 - 120 picks / 10 cm.

[0010] Preferably, the polyphenol substance is levodopa; the metal-organic framework material is CuBTC; the liquid lubricant is perfluoropolyether lubricating oil.

[0011] Preferably, the oil content of the super oil-absorbing PTFE fiber material is 55 - 66 wt%.

[0012] The present invention also provides a preparation method of the super oil-absorbing PTFE fiber material described in the above technical solution, which includes the following steps:

[0013] Immerse one side of the PTFE fiber composite fabric in a buffer solution containing a polyphenol substance and polyethyleneimine for modification to obtain a PTFE fiber composite fabric with a bonding layer;

[0014] Mix the PTFE fiber composite fabric with the bonding layer and the precursor solution of the metal-organic framework material, and carry out a solvothermal reaction to obtain a PTFE fiber composite fabric loaded with the metal-organic framework material;

[0015] Place the PTFE fiber composite fabric loaded with the metal-organic framework material in the liquid lubricant for vacuum impregnation to obtain the super oil-absorbing PTFE fiber material.

[0016] Preferably, the concentration of the polyphenol substance in the buffer solution containing the polyphenol substance and polyethyleneimine is 0.4 - 5 mg / mL, and the concentration of polyethyleneimine is 0.2 - 2 mg / mL.

[0017] Preferably, the precursor solution of the metal-organic framework material includes a metal salt, an organic ligand, and a polar organic solvent; the metal salt is a copper salt; the organic ligand is benzene tricarboxylic acid; the molar ratio of metal ions to organic ligands in the precursor solution of the metal-organic framework material is 1.5 - 2:1; the concentration of metal ions in the precursor solution of the metal-organic framework material is 0.2 - 0.4 mmol / mL.

[0018] Preferably, the temperature of the solvothermal reaction is 80-120 °C; the heat preservation time of the solvothermal reaction is 12-36 h.

[0019] The present invention also provides an application of the super oil-absorbing PTFE fiber material described in the above technical solution or the super oil-absorbing PTFE fiber material prepared by the preparation method described in the above technical solution in a self-lubricating gasket.

[0020] The present invention also provides a self-lubricating gasket, comprising a super oil-absorbing PTFE fiber material and a phenolic resin layer coated on the outer layer of the super oil-absorbing PTFE fiber material; the super oil-absorbing PTFE fiber material is the super oil-absorbing PTFE fiber material described in the above technical solution or the super oil-absorbing PTFE fiber material prepared by the preparation method described in the above technical solution.

[0021] The present invention provides a super oil-absorbing PTFE fiber material, comprising a PTFE fiber composite fabric, a bonding layer, a metal-organic framework material, and a liquid lubricant adsorbed in the pore structure of the metal-organic framework material; the bonding layer is a copolymer of polyphenolic substances and polyethyleneimine; the bonding layer is connected to the PTFE fibers on one side of the PTFE fiber composite fabric through hydrogen bonds; the metal-organic framework material is connected to the bonding layer through an ester bond. The PTFE fibers on one side of the PTFE fiber composite fabric obtain ester groups and hydroxyl active groups through the copolymer of polyphenolic substances and polyethyleneimine. The H on the hydroxyl group and the fluorine atoms in the PTFE fibers form intermolecular hydrogen bonds due to different polarities, so as to connect the bonding layer and the PTFE fibers through hydrogen bonds. The ester groups form ester bond combinations with the metal-organic framework material, so that the metal-organic framework material and the PTFE fibers form a firm chemical bond, avoiding the decrease in the uniformity of the resin material in the self-lubricating gasket caused by the agglomeration or shedding of the metal-organic framework material, and reducing the serious wear resistance loss caused by the decrease in the mechanical properties of the self-lubricating gasket; the metal-organic framework material has a porous structure, a high porosity, and a large specific surface area, and can adsorb a large amount of liquid lubricant, so that the PTFE fiber composite fabric has a super oil-absorbing function. Furthermore, when the super oil-absorbing PTFE fiber material is applied to a self-lubricating gasket, its lubricating performance is improved. At the same time, the introduction of the hard metal-organic framework material can increase the wear resistance of the self-lubricating gasket, so that the self-lubricating gasket prepared with the super oil-absorbing PTFE fiber material has excellent lubricating performance and wear resistance, and improves the service life of the articulated bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic flow chart of the method for preparing the super oil-absorbing PTFE fiber material in the embodiment of the present invention;

[0023] Figure 2Scanning electron microscopy image of the CuBTC-loaded PTFE / basalt twill fabric prepared in Example 2;

[0024] Figure 3 Thermogravimetric curve of the CuBTC-loaded PTFE / basalt twill fabric and the super-oil-absorbing PTFE fiber material in Example 1;

[0025] Figure 4 Thermogravimetric curve of the perfluoropolyether lubricant, the CuBTC-loaded PTFE / basalt twill fabric, and the super-oil-absorbing PTFE fiber material in Example 2;

[0026] Figure 5 Thermogravimetric curve of the CuBTC-loaded PTFE / basalt twill fabric and the super-oil-absorbing PTFE fiber material in Example 3;

[0027] Figure 6 Scanning electron microscopy image of the typical worn surface of the self-lubricating gasket prepared in Application Example 2;

[0028] Figure 7 Scanning electron microscopy image of the typical worn surface of the self-lubricating gasket prepared in Comparative Application Example 1;

[0029] Figure 8 Typical friction coefficient curve comparison chart of the self-lubricating gasket prepared in Application Example 2 and the self-lubricating gasket prepared in Comparative Application Example 1. Detailed implementation manners

[0030] The present invention provides a super-oil-absorbing PTFE fiber material, which includes a PTFE fiber composite fabric, a bonding layer, a metal-organic framework material, and a liquid lubricant adsorbed in the pore structure of the metal-organic framework material; the bonding layer is a copolymer of polyphenolic substances and polyethyleneimine (PEI); the bonding layer is connected to the PTFE fibers on one side of the PTFE fiber composite fabric through hydrogen bonds; the metal-organic framework material is connected to the bonding layer through an ester bond.

[0031] Unless otherwise specified, the present invention has no special requirements for the sources of the raw materials used, and commercially available products well-known to those skilled in the art can be used.

[0032] As an implementation manner, the PTFE fiber composite fabric has a 1 / 3 twill weaving structure; the areal density of the PTFE fiber composite fabric is 300 - 400 g / m 2 , and in specific embodiments, it is 320 - 360 g / m 2 , the warp density is 150 - 180 ends / 10 cm, and in specific embodiments, it is 160 - 170 ends / 10 cm, and the weft density is 100 - 120 picks / 10 cm, and in specific embodiments, it is 110 - 120 picks / 10 cm.

[0033] As an implementation manner, the PTFE fiber composite fabric is woven by using PTFE fibers and high-performance fibers as warp yarns and weft yarns respectively; the equipment used for weaving is an SGA598 semi-automatic loom: the PTFE fibers are from Toray Industries, Inc. (Japan); the high-performance fibers are basalt fibers; the basalt fibers are from Zhejiang Shijin Co., Ltd. (China); both the PTFE fibers and the basalt fibers are untwisted continuous filament yarns; the fineness of the PTFE fibers is 120-150 D, and in specific embodiments, it is 120-130 D; the fineness of the inorganic fibers is 120-150 D, and in specific embodiments, it is 120-130 D. The material characteristics of PTFE fibers have a lubricating function with a low friction coefficient due to the macromolecular layered distribution of the fibers themselves.

[0034] As an implementation manner, the polyphenolic substance is L-DOPA; the metal-organic framework material is CuBTC; the liquid lubricant is perfluoropolyether lubricant; the relative molecular mass of the perfluoropolyether lubricant is 630-1000, and in specific embodiments, it is 700-1000.

[0035] As an implementation manner, the mass ratio of the PTFE fiber composite fabric, the bonding layer and the metal-organic framework material in the super oil-absorbing PTFE fiber material is 8-10:0.1-0.3:3-5, and in specific embodiments, it is 8:0.3:4; the oil content of the super oil-absorbing PTFE fiber material is 55-66 wt%, and in specific embodiments, it is 58-66 wt%.

[0036] On one side of the PTFE fiber composite fabric, the PTFE fibers obtain ester groups and hydroxyl active groups through the copolymer of polyphenolic substances and polyethyleneimine. The H on the hydroxyl group and the fluorine atoms in the PTFE fibers form intermolecular hydrogen bonds due to different polarities, so that the bonding layer and the PTFE fibers are connected by hydrogen bonds. The ester groups form ester bond combinations with the metal-organic framework material, so that the metal-organic framework material and the PTFE fibers form a firm chemical bond, avoiding the decrease in the uniformity of the resin material in the self-lubricating gasket caused by the agglomeration or shedding of the metal-organic framework material, and reducing the serious wear resistance loss caused by the decrease in the mechanical properties of the self-lubricating gasket; the metal-organic framework material has a porous structure, a high porosity and a large specific surface area, and can adsorb more liquid lubricants, so that the PTFE fiber composite fabric has a super oil-absorbing function. Furthermore, when the super oil-absorbing PTFE fiber material is applied to the self-lubricating gasket, its lubricating performance is improved. At the same time, the introduction of the hard metal-organic framework material can increase the wear resistance of the self-lubricating gasket. Therefore, the self-lubricating gasket prepared by using the super oil-absorbing PTFE fiber material has excellent lubricating performance and wear resistance, and improves the service life of the articulated bearing.

[0037] The present invention also provides a method for preparing the super oil-absorbing PTFE fiber material described in the above technical solution, including the following steps:

[0038] One side of the PTFE fiber composite fabric is impregnated in a buffer solution containing polyphenolic substances and polyethyleneimine for modification to obtain a PTFE fiber composite fabric with a bonding layer;

[0039] The PTFE fiber composite fabric with a bonding layer and a precursor solution of a metal-organic framework material are mixed and subjected to a solvothermal reaction to obtain a PTFE fiber composite fabric loaded with a metal-organic framework material;

[0040] The PTFE fiber composite fabric loaded with the metal-organic framework material is placed in a liquid lubricant for vacuum impregnation to obtain a super oil-absorbing PTFE fiber material.

[0041] In the present invention, one side of the PTFE fiber composite fabric is impregnated in a buffer solution containing polyphenolic substances and polyethyleneimine for modification to obtain a PTFE fiber composite fabric with a bonding layer.

[0042] As an implementation manner, the concentration of polyphenolic substances in the buffer solution containing polyphenolic substances and polyethyleneimine is 0.4 - 5 mg / mL, specifically 1 - 4 mg / mL in specific examples, and the concentration of polyethyleneimine is 0.2 - 2 mg / mL, specifically 0.5 - 2 mg / mL in specific examples.

[0043] As an implementation manner, the buffer solution in the buffer solution containing polyphenolic substances and polyethyleneimine is tris(hydroxymethyl)aminomethane hydrochloride buffer solution; the solvent in the tris(hydroxymethyl)aminomethane hydrochloride buffer solution is deionized water; the pH value of the buffer solution containing polyphenolic substances and polyethyleneimine is 7.5 - 8.5, specifically 7.5 - 8 in specific examples.

[0044] As an implementation manner, the temperature of the impregnation is 20 - 22 °C, specifically 22 °C in specific examples; the time of the impregnation is 120 - 360 min, specifically 240 min in specific examples; the impregnation is carried out under stirring; the stirring rate is 200 - 400 rpm, specifically 300 rpm in specific examples.

[0045] Polyphenolic substances and polyethyleneimine polymerize to form a bonding layer containing hydroxyl groups and ester groups. After the surface-inert PTFE fibers are modified by polyphenolic substances and polyethyleneimine, ester groups and hydroxyl active groups are added to the surface of the PTFE fibers.

[0046] After obtaining the PTFE fiber composite fabric with the bonding layer, the present invention mixes the PTFE fiber composite fabric with the bonding layer and the precursor solution of the metal-organic framework material, and performs a solvothermal reaction to obtain a PTFE fiber composite fabric loaded with the metal-organic framework material.

[0047] As an embodiment, the metal-organic framework material is CuBTC; the precursor solution of the metal-organic framework material includes a metal salt, an organic ligand, and a polar organic solvent; the concentration of metal ions in the precursor solution of the metal-organic framework material is 0.2 to 0.4 mmol / mL, specifically 0.24 mmol / mL in the specific embodiment; the molar ratio of metal ions to organic ligands in the precursor solution of the metal-organic framework material is 1.5 to 2:1, specifically 1.5:1 in the specific embodiment; the metal salt is a copper salt; the copper salt is copper nitrate; the organic ligand is benzene tricarboxylic acid; the polar organic solvent is methanol; the preparation method of the precursor solution of the metal-organic framework material is to dissolve the metal salt in the polar organic solvent and add the organic ligand to the obtained metal salt solution; the dissolution is carried out under stirring; the stirring is magnetic stirring; the rate of stirring is 100 to 200 rpm, specifically 100 to 150 rpm in the specific embodiment; the time of stirring is 30 to 60 min, specifically 30 to 40 min in the specific embodiment.

[0048] As an embodiment, before mixing the PTFE fiber composite fabric with the bonding layer and the precursor solution of the metal-organic framework material, it further includes: performing ultrasonic treatment on the precursor solution of the metal-organic framework material; the ultrasonic power of the ultrasonic treatment is 50 to 80 W, specifically 60 W in the specific embodiment, and the range value of the ultrasonic frequency is 38 to 42 kHz, specifically 40 kHz in the specific embodiment; the time of the ultrasonic treatment is 20 to 30 min, specifically 20 min in the specific embodiment. The present invention makes the precursor solution of the metal-organic framework material uniformly mixed through ultrasonic oscillation.

[0049] As an embodiment, the temperature of the solvothermal reaction is 80 to 120 °C, specifically 120 °C in the specific embodiment; the heat preservation time of the solvothermal reaction is 12 to 36 h, specifically 12 h, 24 h, or 36 h in the specific embodiment. In the embodiments of the present invention, the solvothermal reaction is specifically carried out in a high-temperature reaction kettle.

[0050] During the solvothermal reaction process, metal ions in metal salts combine with ester groups on the modified PTFE fibers to form in-situ growth sites. Subsequently, on the in-situ growth sites, organic ligands bridge-coordinate with metal ions to form the basic structural units of metal-organic framework materials. And as the solvothermal reaction proceeds, crystal molecules of metal-organic framework materials continuously precipitate. Most of the metal-organic framework materials are located on the modified PTFE fibers, and a small number are located in the pores between the PTFE fibers.

[0051] In a specific embodiment of the present invention, in the solvothermal reaction, copper ions in copper nitrate combine with ester groups on the PTFE fibers modified by L-DOPA / PEI (modified by L-dopa and polyethyleneimine) to form in-situ growth sites. Subsequently, on the growth sites of the fibers, carboxylic acids in benzene tricarboxylic acid bridge-coordinate with copper ions to form the basic structural units of CuBTC. And as the solvothermal reaction proceeds, CuBTC crystal molecules continuously precipitate. Most of the CuBTC is located on the PTFE fibers modified by L-DOPA / PEI, and a small number are located in the pores between the fibers.

[0052] As an implementation manner, after the solvothermal reaction, it further includes: sequentially washing and drying the PTFE fiber composite fabric after the solvothermal reaction; the washing is immersion washing; the reagent used for washing is anhydrous ethanol; the number of washing times is 3 to 5 times, specifically 3 times in the specific embodiment; the time for each washing is 2 to 5 min, specifically 3 min in the specific embodiment; the drying temperature is 80 to 120 °C, specifically 100 to 120 °C in the specific embodiment; the drying time is 60 to 120 min, specifically 70 to 90 min in the specific embodiment; the equipment used for drying is an oven. The present invention removes the precursor solution of the residual metal-organic framework material through washing.

[0053] After obtaining the PTFE fiber composite fabric loaded with the metal-organic framework material, the present invention immerses the PTFE fiber composite fabric loaded with the metal-organic framework material in a liquid lubricant under vacuum to obtain a super oil-absorbing PTFE fiber material.

[0054] As an implementation manner, the pressure of the vacuum impregnation is 0.07 to 0.08 MPa, specifically 0.08 MPa in the specific embodiment, and the time is 12 to 24 h, specifically 24 h in the specific embodiment; the vacuum impregnation is carried out in a vacuum oven.

[0055] The present invention physically adsorbs the liquid lubricant by using the pore structure of the metal-organic framework material through vacuum impregnation. The vacuum environment can make the metal-organic framework material with a pore structure have a negative pressure state inside the pores, making it easier to adsorb the liquid lubricant.

[0056] As an implementation manner, after the vacuum impregnation, the following steps are further included: successively washing and drying the surface of the PTFE fiber composite fabric loaded with the metal-organic framework material after the vacuum impregnation; the detergent used for washing is n-hexane; the number of washing times is 2 to 4 times, and in a specific embodiment, it is 3 times; the washing process is: soaking the PTFE fiber composite fabric loaded with the metal-organic framework material after the vacuum impregnation in the detergent for washing; the soaking time for each time is 3 to 5 minutes, and in a specific embodiment, it is 3 minutes; the equipment used for drying is a blast drying oven; the drying temperature is 20 to 22 °C, and in a specific embodiment, it is 20 °C; the drying time is 20 to 30 minutes, and in a specific embodiment, it is 20 minutes. The present invention removes the excess lubricant on the surface of the PTFE fiber composite fabric loaded with the metal-organic framework material through washing.

[0057] Figure 1 FIG. is a schematic process flow diagram of the method for preparing the super-oil-absorbing PTFE fiber material in the embodiment of the present invention. In the present invention, L-DOPA (L-dopa) and PEI (polyethyleneimine) are used to modify the surface of PTFE fibers to increase the chemically active sites. The L-DOPA / PEI modified PTFE fibers and the precursor solution of CuBTC are reacted by a hot solvent method to form PTFE fibers with in-situ grown CuBTC. The PTFE fibers loaded with CuBTC are vacuum impregnated with a lubricant to obtain PTFE fibers with an oil-absorbing function.

[0058] In the present invention, CuBTC is in-situ grown on the surface of L-DOPA / PEI modified PTFE fibers. The lubricant is adsorbed by the porous CuBTC, so that the PTFE fibers have the function of super oil absorption. Then, it is applied to a fabric-based self-lubricating gasket. The PTFE fibers with an oil-absorbing function can improve the lubrication performance of the self-lubricating gasket. At the same time, the introduction of hard CuBTC increases the wear resistance of the self-lubricating gasket material.

[0059] The present invention also provides an application of the super-oil-absorbing PTFE fiber material prepared by the above-mentioned preparation method in a self-lubricating gasket.

[0060] The present invention also provides a self-lubricating gasket, which includes a super-oil-absorbing PTFE fiber material and a phenolic resin layer coated on the outer layer of the super-oil-absorbing PTFE fiber material; the super-oil-absorbing PTFE fiber material is the super-oil-absorbing PTFE fiber material described in the above-mentioned technical solution or the super-oil-absorbing PTFE fiber material prepared by the preparation method described in the above-mentioned technical solution.

[0061] As an implementation method, the preparation method of the self-lubricating gasket is as follows: placing the super oil-absorbing PTFE fiber material in a phenolic resin solution for impregnation and then drying to obtain a super oil-absorbing PTFE fiber material coated with phenolic resin; subjecting the super oil-absorbing PTFE fiber material coated with phenolic resin to hot pressing and curing to form the self-lubricating gasket.

[0062] As an implementation method, the solvents in the phenolic resin solution include anhydrous ethanol, acetone, and ethyl acetate; the mass ratio of anhydrous ethanol, acetone, and ethyl acetate is 1:1:1; the mass ratio of phenolic resin to solvent in the phenolic resin solution is 1-2:7-9, and in a specific embodiment, it is 1:7; the number of repetitions of impregnation and then drying is 3-6 times, and in a specific embodiment, it is 5-6 times; the temperature for each impregnation is 20-25 °C, and in a specific embodiment, it is 22 °C; the time for each impregnation is 3-5 min, and in a specific embodiment, it is 3 min; the temperature for each drying is 55-65 °C, and in a specific embodiment, it is 60 °C; the time for each drying is 6-10 min, and in a specific embodiment, it is 10 min; the mass of phenolic resin in the super oil-absorbing PTFE fiber material coated with phenolic resin accounts for 25-35% of the total mass, and in a specific embodiment, it is 30%. Coating with phenolic resin can enhance the strength and shaping of the super oil-absorbing PTFE fiber material.

[0063] As an implementation method, the equipment used for hot pressing and curing is a hot press; the temperature for hot pressing and curing is 180-200 °C, and in a specific embodiment, it is 180 °C, the pressure is 0.3-1 MPa, and in a specific embodiment, it is 0.3 MPa, and the heat preservation and pressure holding time is 2-4 h, and in a specific embodiment, it is 3-4 h.

[0064] In the present invention, through hot pressing and curing, the phenolic resin in the super oil-absorbing PTFE fiber material coated with phenolic resin is cured under high temperature and high pressure conditions and combined with the super oil-absorbing PTFE fiber material to form the required shape in the mold. Hot pressing and curing are based on the resin melting flow property and the influence of pressure and temperature on the behavior of the super oil-absorbing PTFE fiber material. Specifically, during the heating process, the phenolic resin becomes viscous and can fill the gaps between the super oil-absorbing PTFE fibers. At the same time, the applied high pressure can provide better mechanical properties and promote the bonding between fiber layers, thereby achieving better strength and stiffness.

[0065] The self-lubricating gasket has two sides, one side serves as the lubricating surface for mechanical friction, and the other side serves as the bonding surface for bonding with metal. For the fabric-based self-lubricating gasket material, the proportion of the fiber fabric matrix is greater than that of the resin matrix. Therefore, modifying the PTFE fibers with lubricating functions in the fabric matrix can more effectively improve the lubricating performance of the gasket material.

[0066] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0067] Example 1

[0068] (1) Preparation process of PTFE / basalt twill fabric: PTFE fiber untwisted filament yarn (fineness 150D, Toray Co., Ltd. (Japan)) and basalt fiber untwisted filament yarn (fineness 150D, Zhejiang Shijin Co., Ltd. (China)) are used as warp and weft yarns respectively. An SGA598 semi-automatic loom is used to manufacture a hybrid fabric with a 1 / 3 twill weave structure. The warp density is 160 ends / 10 cm, the weft density is 120 ends / 10 cm, and the areal density of the prepared PTFE / basalt twill fabric is 320 g / m 2 ;

[0069] (2) Immerse one side of the PTFE / basalt twill fabric in a tris(hydroxymethyl)aminomethane hydrochloride buffer solution (pH = 7.5, solvent is deionized water) containing 4 mg / mL levodopa (L-DOPA) and 2 mg / mL polyethyleneimine (PEI) for 240 min at a temperature of 22 °C and a stirring rate of 300 rpm for modification to form a copolymer adhesion layer of levodopa and polyethyleneimine, obtaining a PTFE / basalt twill fabric with an L-DOPA / PEI adhesion layer;

[0070] (3) Dissolve copper nitrate in methanol under magnetic stirring at 100 rpm for 30 min, and then add benzene-1,3,5-tricarboxylic acid to the obtained methanol solution of copper nitrate. Here, the concentration of copper ions is 0.24 mmol / mL, and the molar ratio of copper ions to benzene-1,3,5-tricarboxylic acid is 1.5:1, obtaining a precursor solution of CuBTC;

[0071] (4) Ultrasonically treat the precursor solution of CuBTC at a power of 60 W and a frequency of 40 kHz for 20 min, then place the PTFE / basalt twill fabric with an L-DOPA / PEI adhesion layer in the ultrasonically treated precursor solution of CuBTC, put it into a reaction kettle, carry out a solvothermal reaction at 120 °C for 12 h. After the reaction ends, wait for the reaction solution to cool to room temperature, soak and wash the PTFE / basalt twill fabric after the solvent reaction with absolute ethanol 3 times, 3 min each time, and then place it in an oven to dry at 120 °C for 90 min, obtaining a CuBTC-loaded PTFE / basalt twill fabric;

[0072] (5) Place the CuBTC-loaded PTFE / basalt twill fabric in perfluoropolyether lubricating oil with a relative molecular mass of 1000 in a vacuum oven at 0.08 MPa for vacuum impregnation for 24 h. Then take out the fabric and soak it in n-hexane to wash the excess perfluoropolyether lubricating oil on the surface. Repeat the washing 3 times, and then place it in a blast drying oven and dry it at 20 °C for 20 min to obtain the super oil-absorbing PTFE fiber material.

[0073] Example 2

[0074] (1) Immerse one side of the PTFE / basalt twill fabric (prepared in the same way as in Example 1) in a tris(hydroxymethyl)aminomethane hydrochloride buffer solution (pH = 7.5, solvent is deionized water) containing 4 mg / mL levodopa and 2 mg / mL polyethyleneimine for 240 min at a temperature of 22 °C and a stirring rate of 300 rpm for modification to form a copolymer adhesion layer of levodopa and polyethyleneimine, and obtain the PTFE / basalt twill fabric with an L-DOPA / PEI adhesion layer.

[0075] (2) Dissolve copper nitrate in methanol under magnetic stirring at 100 rpm for 30 min, and then add trimesic acid to the obtained methanol solution of copper nitrate. Among them, the concentration of copper ions is 0.24 mmol / mL, and the molar ratio of copper ions to trimesic acid is 1.5:1 to obtain the precursor solution of CuBTC.

[0076] (3) Ultrasonically treat the precursor solution of CuBTC at a power of 60 W and a frequency of 40 kHz for 20 min, and then place the PTFE / basalt twill fabric with an L-DOPA / PEI adhesion layer in the ultrasonically treated precursor solution of CuBTC, put it into a reaction kettle, and carry out a solvothermal reaction at 120 °C for 24 h. After the reaction is completed, wait for the reaction solution to cool to room temperature, soak and wash the PTFE / basalt twill fabric after the solvent reaction 3 times with anhydrous ethanol, 3 min each time, and then place it in an oven and dry it at 120 °C for 90 min to obtain the CuBTC-loaded PTFE / basalt twill fabric.

[0077] (3) Place the CuBTC-loaded PTFE / basalt twill fabric in perfluoropolyether lubricating oil with a relative molecular mass of 1000 in a vacuum oven at 0.08 MPa for vacuum impregnation for 24 h. Then take out the fabric and soak it in n-hexane to wash the excess perfluoropolyether lubricating oil on the surface. Repeat the washing 3 times, and then place it in a blast drying oven and dry it at 20 °C for 20 min to obtain the super oil-absorbing PTFE fiber material.

[0078] Example 3

[0079] (1) Immerse one side of the PTFE / basalt twill fabric (prepared in the same way as in Example 1) in a tris(hydroxymethyl)aminomethane hydrochloride buffer solution (pH = 7.5, solvent is deionized water) containing 4 mg / mL levodopa and 2 mg / mL polyethyleneimine for 240 min at a temperature of 22 °C and a stirring rate of 300 rpm for modification to form a copolymer adhesion layer of levodopa and polyethyleneimine, and obtain a PTFE / basalt twill fabric with an L-DOPA / PEI adhesion layer;

[0080] (2) Dissolve copper nitrate in methanol under magnetic stirring at 100 rpm for 30 min, and then add benzene-1,3,5-tricarboxylic acid to the obtained methanol solution of copper nitrate. The concentration of copper ions is 0.24 mmol / mL, and the molar ratio of copper ions to benzene-1,3,5-tricarboxylic acid is 1.5:1 to obtain a precursor solution of CuBTC;

[0081] (3) Ultrasonically treat the precursor solution of CuBTC at a power of 60 W and a frequency of 40 kHz for 20 min, then place the PTFE / basalt twill fabric with an L-DOPA / PEI adhesion layer in the ultrasonically treated precursor solution of CuBTC, put it into a reaction kettle, and carry out a solvothermal reaction at 120 °C for 36 h. After the reaction is completed, wait for the reaction solution to cool to room temperature, soak and wash the PTFE / basalt twill fabric after the solvent reaction with absolute ethanol 3 times, 3 min each time, and then place it in an oven to dry at 120 °C for 90 min to obtain a PTFE / basalt twill fabric loaded with CuBTC;

[0082] (3) Place the PTFE / basalt twill fabric loaded with CuBTC in a perfluoropolyether lubricating oil with a relative molecular mass of 1000 and carry out vacuum impregnation in a vacuum oven at 0.08 MPa for 24 h. Then take out the fabric and soak it in n-hexane to wash the excess perfluoropolyether lubricating oil on the surface, repeat the washing 3 times, and then place it in a forced-air oven to dry at 20 °C for 20 min to obtain a super oil-absorbing PTFE fiber material.

[0083] Comparative Example 1

[0084] Use the unmodified PTFE / basalt twill fabric (prepared in the same way as in Example 1) as the comparative example.

[0085] Comparative Example 2

[0086] Use the PTFE / basalt twill fabric with an adhesion layer prepared in Example 1 as the comparative example.

[0087] Application Example 1

[0088] The superabsorbent PTFE fiber material prepared in Example 1 was immersed in a phenolic resin solution (the solvent was anhydrous ethanol, acetone, and ethyl acetate with a mass ratio of 1:1:1, and the mass ratio of phenolic resin to solvent was 1:7) at 22°C for 3 minutes, and then dried at 60°C for 10 minutes. The steps of immersion and drying were repeated 6 times to obtain a superabsorbent PTFE fiber material coated with phenolic resin, wherein the mass of phenolic resin accounted for 30% of the total mass;

[0089] The superabsorbent PTFE fiber material coated with phenolic resin was placed in a hot press for hot pressing and curing molding at a temperature of 180°C, a pressure of 0.3 MPa, and a time of 3 hours to obtain a self-lubricating gasket with a superabsorbent PTFE fiber material.

[0090] Application Examples 2 - 3

[0091] The difference from Application Example 1 was that the superabsorbent PTFE fiber material prepared in Example 1 was replaced with the superabsorbent PTFE fiber material prepared in Example 2 and the superabsorbent PTFE fiber material prepared in Example 3 respectively, and the rest of the content was the same as that in Application Example 1.

[0092] Comparative Application Example 1

[0093] The difference from Application Example 1 was that the superabsorbent PTFE fiber material prepared in Example 1 was replaced with the unchemically modified PTFE / basalt twill fabric in Comparative Example 1. After rinsing it with alcohol and drying it, then in the same steps as Application Example 1, it was immersed in the phenolic resin solution, dried, and hot pressed and cured to obtain a self-lubricating gasket.

[0094] Comparative Application Example 2

[0095] The difference from Application Example 1 was that the superabsorbent PTFE fiber material prepared in Example 1 was replaced with the PTFE / basalt twill fabric with an L-DOPA / PEI bonding layer in Comparative Example 2, and the rest of the content was the same as that in Application Example 1 to obtain a self-lubricating gasket with a PTFE / basalt twill fabric with an L-DOPA / PEI bonding layer.

[0096] Performance Test

[0097] (1) Figure 2 It is the scanning electron micrograph of the CuBTC-loaded PTFE / basalt twill fabric prepared in Example 2.

[0098] From Figure 2 it can be seen that CuBTC particles grew uniformly on the PTFE fibers.

[0099] (2) Figure 3Thermogravimetric curves of the PTFE / basalt twill fabric loaded with CuBTC (PTFE loaded with CuBTC) and the super oil-absorbing PTFE fiber material (PTFE loaded with oil-absorbing CuBTC) in Example 1.

[0100] It can be obtained from Figure 3 that the oil content of the super oil-absorbing PTFE fiber material prepared in Example 1 is 58.5 wt%.

[0101] (3) Figure 4 Thermogravimetric curves of the perfluoropolyether lubricant (perfluoropolyether oil), the PTFE / basalt twill fabric loaded with CuBTC (PTFE loaded with CuBTC) and the super oil-absorbing PTFE fiber material (PTFE loaded with oil-absorbing CuBTC) in Example 2.

[0102] It can be obtained from Figure 4 that the oil content of the super oil-absorbing PTFE fiber material prepared in Example 2 is 65.9 wt%.

[0103] (4) Figure 5 Thermogravimetric curves of the PTFE / basalt twill fabric loaded with CuBTC (PTFE loaded with CuBTC) and the super oil-absorbing PTFE fiber material (PTFE loaded with oil-absorbing CuBTC) in Example 3.

[0104] It can be obtained from Figure 5 that the oil content of the super oil-absorbing PTFE fiber material prepared in Example 3 is 65.8 wt%.

[0105] (5) Figure 6 Typical scanning electron microscope image of the worn surface of the self-lubricating gasket prepared in Application Example 2.

[0106] It can be seen from Figure 6 the scanning electron microscope image of the worn surface of the material of the self-lubricating gasket prepared in Application Example 2 after the friction test that its surface is flat without broken fiber extraction, indicating that the self-lubricating gasket prepared with the super oil-absorbing PTFE fiber material prepared by the present invention has a positive effect on improving the bonding between the fiber matrix and the resin of the gasket material, making the overall tribological morphology of the self-lubricating gasket excellent.

[0107] (6) Figure 7 Typical scanning electron microscope image of the worn surface of the self-lubricating gasket prepared in Comparative Application Example 1.

[0108] It can be seen from Figure 7 that the self-lubricating gasket in Comparative Application Example 1 is prepared from unmodified PTFE / basalt twill fabric, and fragments of fiber fracture and wear debris can be seen on its surface, indicating that the bonding between the fiber matrix and the resin matrix is not strong and the tribological performance of the material is average.

[0109] (7) Figure 8 Typical friction coefficient curve comparison diagram of the self-lubricating gasket prepared in Application Example 2 and the self-lubricating gasket prepared in Comparative Application Example 1.

[0110] From Figure 8 it can be seen that compared with the friction coefficient curve of Comparative Application Example 1, the curve of Application Example 2 drops significantly and the curve trend keeps decreasing, but the fluctuation is more intense than the original. It can be known that the super-absorbent PTFE fiber material prepared by the present invention has the effect of reducing the friction coefficient of the self-lubricating gasket. At the same time, the hard three-dimensional particles CuBTC increase the roughness of the friction interface during the friction process and increase the fluctuation during the friction process.

[0111] (8) Friction tests were carried out on the self-lubricating gaskets of Application Examples 1 to 3 and Comparative Application Examples 1 to 2 under the conditions of: load 15 N, rotational speed 0.141 m / s, and test duration 120 min. The results are shown in Table 1.

[0112] Table 1 Friction test results of the self-lubricating gaskets of Application Examples 1 to 3 and Comparative Application Examples 1 to 2

[0113] Number Average coefficient of friction μ <![CDATA[Wear rate 10 -13 m 3 / N·m]]> Application Example 1 0.1548 1.31 Application Example 2 0.1474 1.25 Application Example 3 0.1513 1.27 Comparative Application Example 1 0.2018 2.11 Comparative Application Example 2 0.1895 2.02

[0114] It can be seen from Table 1 that the friction test results of Application Example 2 and Comparative Application Example 1 show that the friction coefficient and wear rate of the self-lubricating gasket prepared from the super-absorbent PTFE fiber material prepared by the present invention are both reduced. The tribological mechanism is that the release of the perfluoropolyether lubricating oil adsorbed by CuBTC promotes the formation of a solid-liquid synergistic lubrication composed of the liquid lubricant and the PTFE fiber with lubricating function, so the friction coefficient can be significantly reduced. At the same time, the hard CuBTC fills the friction interface during the friction process, enhancing the strength of the friction interface, so its wear rate also decreases. Therefore, the super-absorbent PTFE fiber has good tribological performance in the application of self-lubricating gaskets.

[0115] The results of Application Examples 1 to 3 show that the change in the synthesis time of the oil storage medium CuBTC affects the change in its oil content, and ultimately affects the change in the tribological performance of the self-lubricating gasket. Specifically, Application Example 2 with the highest oil content shows the best friction coefficient and wear rate, while Application Example 1 with the lowest oil content has the largest friction coefficient and the worst lubrication performance; and Application Example 3 with a medium oil content has the second-best tribological performance.

[0116] The test results of Comparative Example 1 and Comparative Example 2 show that the modified adhesive layer of PTFE fiber with L-DOPA / PEI also has a certain improvement effect on the tribological performance of the self-lubricating gasket.

[0117] Although the above embodiments have described the present invention in detail, they are only some rather than all embodiments of the present invention. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A super oil-absorbing PTFE fiber material, characterized in that, It includes a PTFE fiber composite fabric, a bonding layer, a metal-organic framework material, and a liquid lubricant adsorbed in the pore structure of the metal-organic framework material; the bonding layer is a copolymer of polyphenolic substances and polyethyleneimine; the bonding layer is connected to the PTFE fibers on one side of the PTFE fiber composite fabric through hydrogen bonds; the metal-organic framework material is connected to the bonding layer through an ester bond.

2. The super oil-absorbing PTFE fiber material according to claim 1, wherein The PTFE fiber composite fabric has a 1 / 3 twill weave structure; the areal density of the PTFE fiber composite fabric is 300-400 g / m 2 , the warp density is 150-180 ends / 10 cm, and the weft density is 100-120 picks / 10 cm.

3. The super oil-absorbing PTFE fiber material according to claim 1, characterized in that, The polyphenolic substance is levodopa; the metal-organic framework material is CuBTC; the liquid lubricant is perfluoropolyether lubricant.

4. The super oil-absorbing PTFE fiber material according to claim 1, characterized in that, The oil content of the super oil-absorbing PTFE fiber material is 55-66 wt%.

5. The preparation method of the super oil-absorbing PTFE fiber material according to any one of claims 1 to 4, characterized in that, It includes the following steps: Immerse one side of the PTFE fiber composite fabric in a buffer solution containing polyphenolic substances and polyethyleneimine for modification to obtain a PTFE fiber composite fabric with a bonding layer. Mix the PTFE fiber composite fabric with the bonding layer and the precursor solution of the metal-organic framework material, and carry out a solvothermal reaction to obtain a PTFE fiber composite fabric loaded with the metal-organic framework material. Place the PTFE fiber composite fabric loaded with the metal-organic framework material in a liquid lubricant for vacuum impregnation to obtain a super oil-absorbing PTFE fiber material.

6. The preparation method according to claim 5, characterized in that, In the buffer solution containing polyphenolic substances and polyethyleneimine, the concentration of the polyphenolic substance is 0.4-5 mg / mL, and the concentration of polyethyleneimine is 0.2-2 mg / mL.

7. The preparation method according to claim 5, characterized in that, The precursor solution of the metal-organic framework material includes a metal salt, an organic ligand, and a polar organic solvent; the metal salt is a copper salt; the organic ligand is benzene tricarboxylic acid; the molar ratio of metal ions to organic ligands in the precursor solution of the metal-organic framework material is 1.5-2:1; the concentration of metal ions in the precursor solution of the metal-organic framework material is 0.2-0.4 mmol / mL.

8. The preparation method according to claim 5, wherein The temperature of the solvothermal reaction is 80-120 °C; the heat preservation time of the solvothermal reaction is 12-36 h.

9. Application of the super oil-absorbing PTFE fiber material according to any one of claims 1-4 or the super oil-absorbing PTFE fiber material prepared by the preparation method according to any one of claims 5-8 in a self-lubricating gasket.

10. A self-lubricating gasket, characterized in that, It includes a super oil-absorbing PTFE fiber material and a phenolic resin layer coated on the outer layer of the super oil-absorbing PTFE fiber material; the super oil-absorbing PTFE fiber material is the super oil-absorbing PTFE fiber material according to any one of claims 1-4 or the super oil-absorbing PTFE fiber material prepared by the preparation method according to any one of claims 5-8.

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