Polytetrafluoroethylene composition, polytetrafluoroethylene composite material, preparation method of polytetrafluoroethylene composite material and sealing material

Abstract

The invention relates to a polytetrafluoroethylene composition, a polytetrafluoroethylene composite material, a preparation method of the polytetrafluoroethylene composite material and a sealing material. The polytetrafluoroethylene composition comprises polytetrafluoroethylene, graphene and a creep resistant agent, wherein the mass ratio of the graphene to the polytetrafluoroethylene is (0.1-1): 100. According to the polytetrafluoroethylene composition, polytetrafluoroethylene is used as a matrix, graphene and a creep-resistant agent are used as fillers, and the mass ratio of graphene to polytetrafluoroethylene is controlled, so that the fillers and the matrix have better compatibility, the lamellar structure of graphene is promoted to fully play a lubricating role, and the friction coefficient of the polytetrafluoroethylene composition is effectively reduced; meanwhile, the graphene is promoted to give full play to the heat conduction effect, heat generated by friction is effectively transferred, and adhesive wear caused by friction heat is reduced, so that the wear resistance of the polytetrafluoroethylene composition is effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of polymer materials, and in particular to a polytetrafluoroethylene composition, a polytetrafluoroethylene composite material, a preparation method thereof, and a sealing material. Background Art

[0002] Polytetrafluoroethylene (PTFE) is a fluoroplastic that can be used for extended periods at temperatures between -180°C and 260°C. It exhibits excellent high- and low-temperature resistance, chemical stability, aging resistance, corrosion resistance, and high lubricity, making it a common sealing material in aerospace, petrochemical, and mining machinery applications. However, pure PTFE exhibits poor wear resistance and, under long-term stress and friction, exhibits poor dimensional stability and a short service life, leading to seal failure. Summary of the Invention

[0003] Based on this, the present application provides a polytetrafluoroethylene composition, a polytetrafluoroethylene composite material and a preparation method thereof, and a sealing material with a low friction coefficient and good wear resistance.

[0004] The technical solution of this application to solve the above technical problems is as follows.

[0005] In a first aspect, the present application provides a polytetrafluoroethylene composition comprising polytetrafluoroethylene, graphene, and an anti-creep agent, wherein the mass ratio of the graphene to the polytetrafluoroethylene is (0.1-1):100.

[0006] In some embodiments, in the polytetrafluoroethylene composition, the mass ratio of the graphene to the polytetrafluoroethylene is (0.2-0.7):100;

[0007] And / or, the mass ratio of the anti-creep agent to the polytetrafluoroethylene is (10-20):100.

[0008] In some embodiments, in the polytetrafluoroethylene composition, the anti-creep agent includes at least one of polyphenylene sulfide and polyimide.

[0009] In some embodiments, in the polytetrafluoroethylene composition, the polyphenylene sulfide is modified polyphenylene sulfide, and the modifier of the modified polyphenylene sulfide includes glass fiber and polytetrafluoroethylene.

[0010] In some embodiments, the polytetrafluoroethylene composition further comprises PFA, and the mass ratio of the PFA to the polytetrafluoroethylene is (4-10):100.

[0011] In some embodiments, in the polytetrafluoroethylene composition, the PFA and the graphene form graphene / PFA hybrid fibers, and in the graphene / PFA hybrid fibers, the PFA is coated on the surface of the graphene.

[0012] In some embodiments, in the polytetrafluoroethylene composition, the specific surface area of ​​the graphene is 400 m 2 / g~600 m 2 / g;

[0013] And / or, the average particle size of the graphene is 5 μm to 15 μm;

[0014] And / or, the average particle size of the polytetrafluoroethylene is 15 μm to 25 μm;

[0015] And / or, the bulk density of the polytetrafluoroethylene is 0.3 g / cm 3 ~1 g / cm 3 .

[0016] A second aspect of the present application provides a method for preparing a polytetrafluoroethylene composition, comprising the following steps:

[0017] Polytetrafluoroethylene, graphene and an anti-creep agent are mixed to prepare a polytetrafluoroethylene composition; the mass ratio of the graphene to the polytetrafluoroethylene is (0.1~1):100.

[0018] In some embodiments, in the method for preparing a polytetrafluoroethylene composition, the polytetrafluoroethylene composition further comprises PFA, and the PFA and the graphene form a graphene / PFA hybrid fiber. The preparation of the graphene / PFA hybrid fiber comprises the following steps:

[0019] The PFA and the graphene are mixed and then granulated, sliced, melt-spun and heat-treated in sequence to prepare graphene / PFA hybrid fibers.

[0020] A third aspect of the present application provides a polytetrafluoroethylene composite material, comprising the polytetrafluoroethylene composition provided in the first aspect or a polytetrafluoroethylene composition prepared by the preparation method of the polytetrafluoroethylene composition provided in the second aspect.

[0021] A fourth aspect of the present application provides a method for preparing a polytetrafluoroethylene composite material, comprising the following steps:

[0022] The polytetrafluoroethylene composition provided in the first aspect or the polytetrafluoroethylene composition prepared by the preparation method of the polytetrafluoroethylene composition provided in the second aspect is subjected to molding treatment and sintering treatment in sequence to prepare a polytetrafluoroethylene composite material.

[0023] The fifth aspect of the present application provides a sealing material, comprising the polytetrafluoroethylene composition provided by the first aspect, the polytetrafluoroethylene composition prepared by the preparation method of the polytetrafluoroethylene composition provided by the second aspect, the polytetrafluoroethylene composite material provided by the third aspect, or the polytetrafluoroethylene composite material prepared by the preparation method of the polytetrafluoroethylene composite material provided by the fourth aspect.

[0024] The polytetrafluoroethylene composition of the present application uses polytetrafluoroethylene as a matrix, graphene and an anti-creep agent as fillers, and controls the mass ratio of graphene to polytetrafluoroethylene to ensure good compatibility between the filler and the matrix, thereby enabling the graphene's lamellar structure to fully play a lubricating role, effectively reducing the friction coefficient of the polytetrafluoroethylene composition, and simultaneously enabling the graphene to fully exert its thermal conductivity, effectively transferring heat generated by friction, reducing adhesive wear caused by frictional heat, and thus effectively improving the wear resistance of the polytetrafluoroethylene composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application and to more fully understand the present application and its beneficial effects, the following is a brief introduction to the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0026] Figure 1 The graphs are compression creep curves of the composite materials prepared in some examples and comparative examples. DETAILED DESCRIPTION

[0027] The present application will be further described in detail below in conjunction with the embodiments and examples. It should be understood that these embodiments and examples are only intended to illustrate the present application and are not intended to limit the scope of the present application. The purpose of providing these embodiments and examples is to provide a more thorough and comprehensive understanding of the disclosure of the present application.

[0028] It should also be understood that the present application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various changes or modifications without violating the connotation of the present application, and the resulting equivalent forms also fall within the scope of protection of the present application. For example, features illustrated or described as part of one embodiment can be combined in a suitable manner in another embodiment to produce a new embodiment. In addition, in the description below, a large number of specific details are given in order to provide a more complete understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing embodiments and examples only and are not intended to limit this application.

[0030] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0031] In this application, "plurality", "multiple", "multiple times", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more than or equal to two.

[0032] As used herein, "combination thereof", "any combination thereof", "any combination thereof" and the like include all suitable combinations of any two or more of the listed items.

[0033] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc. shall be based on the ability to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0034] Herein, the terms "preferred," "better," "more preferred," and "suitable" are used solely to describe preferred implementations or examples and should not be construed as limiting the scope of protection of this application. If multiple "preferred" terms appear in a technical solution, each "preferred" term is considered independent unless otherwise specified and there are no contradictions or mutual constraints.

[0035] In this application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of this application.

[0036] In this application, the terms "optionally," "optional," and "optional" mean optional or dispensable, i.e., they refer to either option being selected from two parallel options: "with" or "without." If a technical solution contains multiple "optional" clauses, each "optional" clause is independent unless otherwise specified and there are no contradictions or constraints.

[0037] In this application, the terms "first," "second," "third," "fourth," etc. in "the first aspect," "the second aspect," "the third aspect," "the fourth aspect," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor should they be understood as implicitly indicating the importance or quantity of the indicated technical features. Furthermore, "first," "second," "third," "fourth," etc. serve only as non-exhaustive enumeration and description, and should be understood not to constitute a closed-ended limitation on quantity.

[0038] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0039] In this application, when referring to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​within the numerical interval is deemed to be continuous and includes the two numerical endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two numerical endpoints. Unless otherwise specified, when a numerical interval refers only to integers within the numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe a feature or characteristic, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. "Numerical interval" allows for a broad range of numerical interval types including percentage intervals, ratio intervals, and ratio intervals.

[0040] Unless otherwise specified, the temperature parameters in this application allow for both constant temperature treatment and temperature fluctuations within a certain temperature range. It should be understood that the constant temperature treatment allows for temperature fluctuations within the accuracy range of instrument control. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are permitted.

[0041] In this application, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, for example, 20°C ± 5°C. In some embodiments of this application, "room temperature" or "normal temperature" refers to 10°C to 30°C. In some embodiments of this application, "room temperature" or "normal temperature" refers to 20°C to 30°C.

[0042] In this application, when referring to a range of units, if the unit is only after the right endpoint, it means that the units of the left and right endpoints are the same. For example, 3~5h means that the units of the left endpoint "3" and the right endpoint "5" are both hours.

[0043] All documents mentioned in this application are cited as references in this application, just as each document is cited as a reference individually. Unless they conflict with the invention purpose and / or technical solution of this application, the cited documents involved in this application are cited in their entirety and for all purposes. When cited documents are involved in this application, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When cited documents are involved in this application, the examples and preferred embodiments of the cited relevant technical features may also be incorporated into this application as references, but are limited to the ability to implement this application. It should be understood that when the cited content conflicts with the description in this application, the present application shall prevail or be adaptively amended according to the description in this application.

[0044] The mass or weight of the relevant components mentioned in the examples of this application may not only refer to the specific content of each component, but also represent the proportional relationship of the mass or weight of each component. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the examples of this application, it is within the scope disclosed in the examples of this application. Specifically, the mass or weight described in the examples of this application may be units known in the chemical industry such as μg, mg, g, and kg.

[0045] Pure polytetrafluoroethylene (PTFE) has poor compression creep resistance, low load-bearing capacity, and is susceptible to wear. Under long-term stress and friction, it suffers from poor dimensional stability, a short service life, and prone to seal failure. Physical modification of PTFE, blending fillers with it, can address these deficiencies while maintaining the excellent properties of the original PTFE. However, due to the poor compatibility of chemically inert PTFE with inorganic fillers (such as carbon fiber, copper powder, and wollastonite), problems often arise during use, including increased friction due to filler shedding and decreased mechanical properties caused by stress concentration.

[0046] One embodiment of the present application provides a polytetrafluoroethylene composition, comprising polytetrafluoroethylene (PTFE), graphene, and an anti-creep agent, wherein the mass ratio of graphene to polytetrafluoroethylene is (0.1-1):100.

[0047] In the polytetrafluoroethylene composition, polytetrafluoroethylene is used as a matrix, graphene and an anti-creep agent are used as fillers, and the mass ratio of graphene to polytetrafluoroethylene is controlled to ensure good compatibility between the filler and the matrix, thereby enabling the graphene's lamellar structure to fully play a lubricating role, effectively reducing the friction coefficient of the polytetrafluoroethylene composition, and at the same time enabling the graphene to fully exert its thermal conductivity, effectively transferring the heat generated by friction, reducing adhesive wear caused by frictional heat, and thus effectively improving the wear resistance of the polytetrafluoroethylene composition.

[0048] In addition, the polytetrafluoroethylene composition of the present application has good compatibility between graphene, anti-creep agent and polytetrafluoroethylene, which improves the dispersion stability of the filler. The rigid structure in the anti-creep agent molecules can limit the slip of the polytetrafluoroethylene lattice under the action of external force, thereby effectively improving the compression creep performance of the polytetrafluoroethylene composition.

[0049] It can be understood that the mass ratio of graphene to polytetrafluoroethylene includes but is not limited to 0.1:100, 0.2:100, 0.3:100, 0.4:100, 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, and 1:100; in some examples, it can be within the range formed by any two of these point values ​​as end values, the same below.

[0050] In some of the examples, the mass ratio of graphene to polytetrafluoroethylene in the polytetrafluoroethylene composition is (0.2~0.7):100.

[0051] In some of the examples, in the polytetrafluoroethylene composition, the mass ratio of the anti-creep agent to the polytetrafluoroethylene is (10-20):100.

[0052] It will be appreciated that the mass ratio of the anti-creep agent to polytetrafluoroethylene includes, but is not limited to, 10:100, 11:100, 12:100, 13:100, 14:100, 15:100, 16:100, 17:100, 18:100, 19:100, and 20:100.

[0053] In some of the examples, in the polytetrafluoroethylene composition, the mass ratio of the anti-creep agent to the polytetrafluoroethylene is (12-18):100.

[0054] In some examples, in the polytetrafluoroethylene composition, the anti-creep agent includes at least one of polyphenylene sulfide (PPS) and polyimide (PI).

[0055] In some of the examples, in the polytetrafluoroethylene composition, the polyphenylene sulfide is modified polyphenylene sulfide, and the modifier of the modified polyphenylene sulfide includes glass fiber and polytetrafluoroethylene (PTFE).

[0056] It is understood that the polyphenylene sulfide can be modified using the above-mentioned modifiers by conventional methods, for example, by blending and modifying using an extruder.

[0057] The modified polyphenylene sulfide contains polytetrafluoroethylene, which can further increase the compatibility of the anti-creep agent and the matrix polytetrafluoroethylene and improve the dispersion stability.

[0058] In some examples, in the polytetrafluoroethylene composition, the modified polyphenylene sulfide includes Torelina A515.

[0059] In some of the examples, the polytetrafluoroethylene composition further includes PFA, and the mass ratio of PFA to polytetrafluoroethylene is (4-10):100.

[0060] It can be understood that PFA is fusible polytetrafluoroethylene, which is a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer with a melt index of 15 g / 10min.

[0061] It can be understood that the introduction of comonomers in fusible polytetrafluoroethylene (PFA) reduces the regularity of the molecular chain and the melting temperature, and can be molded by extrusion or injection molding like ordinary plastics; while PTFE is made of tetrafluoroethylene homopolymer, which is difficult to melt and is usually molded by compression molding.

[0062] It can also be understood that the mass ratio of PFA to polytetrafluoroethylene includes but is not limited to 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, and 10:100.

[0063] In some of the examples, in a polytetrafluoroethylene composition, PFA and graphene form graphene / PFA hybrid fibers, in which PFA is coated on the surface of graphene.

[0064] PFA has a similar molecular structure to polytetrafluoroethylene. By coating graphene with PFA, the compatibility between graphene and polytetrafluoroethylene is further enhanced, improving the dispersion stability of graphene and preventing agglomeration. The graphene can also be shaped into a fibrous, staggered arrangement within the polytetrafluoroethylene, increasing the compressive creep resistance of the polytetrafluoroethylene composition. PFA itself has poor wear resistance, but by combining PFA with graphene to form graphene / PFA hybrid fibers, the wear resistance of the polytetrafluoroethylene composition can be further improved.

[0065] In some of these examples, the aspect ratio of graphene / PFA hybrid fibers is (10~15):1.

[0066] It can be understood that the aspect ratio of the graphene / PFA hybrid fiber includes but is not limited to 10:1, 11:1, 12:1, 13:1, 14:1, and 15:1.

[0067] It can be understood that in the graphene / PFA hybrid fiber, the mass ratio of graphene to PFA is (0.1~1):(4~10); optionally, the mass ratio of graphene to PFA is (0.01~0.25):1.

[0068] It will be appreciated that the mass ratio of graphene to PFA includes, but is not limited to, 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.10:1, 0.11:1, 0.12:1, 0.13:1, 0.14:1, 0.15:1, 0.16:1, 0.17:1, 0.18:1, 0.19:1, 0.20:1, 0.21:1, 0.22:1, 0.23:1, 0.24:1, and 0.25:1.

[0069] In some examples, in the graphene / PFA hybrid fiber, the mass ratio of graphene to PFA is (0.05-0.2): 1. Alternatively, the mass ratio of graphene to PFA is (0.06-0.16): 1.

[0070] In some examples, graphene in a polytetrafluoroethylene composition has a specific surface area of ​​400 m 2 / g~600 m 2 / g.

[0071] In some of these examples, the average particle size of graphene in the polytetrafluoroethylene composition is 5 μm to 15 μm.

[0072] In some of these examples, the average particle size of the polytetrafluoroethylene in the polytetrafluoroethylene composition is 15 μm to 25 μm.

[0073] In some of these examples, the bulk density of the polytetrafluoroethylene in the polytetrafluoroethylene composition is 0.3 g / cm 3 ~1g / cm 3 .

[0074] In some of the examples, the polytetrafluoroethylene composition is composed of polytetrafluoroethylene, graphene / PFA hybrid fiber and modified polyphenylene sulfide.

[0075] One embodiment of the present application provides a method for preparing a polytetrafluoroethylene composition, comprising the following steps:

[0076] Polytetrafluoroethylene, graphene and an anti-creep agent are mixed to prepare a polytetrafluoroethylene composition; the mass ratio of graphene to polytetrafluoroethylene is (0.1-1):100.

[0077] It is understood that polytetrafluoroethylene can be prepared as a powder by suspension polymerization.

[0078] In some examples, in the method for preparing a polytetrafluoroethylene composition, polytetrafluoroethylene, graphene, and an anti-creep agent are sequentially added to a high-speed mixer and mixed. Optionally, the speed of the high-speed mixer is 3000 r / min to 4000 r / min; and the mixing temperature is controlled below 15°C.

[0079] In some examples, in the method for preparing a polytetrafluoroethylene composition, the polytetrafluoroethylene composition further includes PFA, and the PFA and graphene form a graphene / PFA hybrid fiber. The preparation of the graphene / PFA hybrid fiber includes the following steps:

[0080] PFA and graphene are mixed and then granulated, sliced, melt-spun and heat-treated in sequence to prepare graphene / PFA hybrid fibers.

[0081] Graphene is wrapped inside PFA through granulation, slicing, and melt spinning processes. The hybrid fiber can effectively improve the compatibility between graphene and polytetrafluoroethylene matrix, so that the graphene is arranged in a fibrous and staggered manner in polytetrafluoroethylene, giving full play to the high thermal conductivity of graphene, quickly transferring frictional heat, and preventing the fall of fillers during friction. Combined with the rigid structure of the anti-creep agent, it can not only increase the mechanical properties of the polytetrafluoroethylene composition, but also improve the wear resistance and compression creep resistance of the polytetrafluoroethylene composition.

[0082] The study found that if PFA and graphene are directly mixed and melt-spun, the spinneret will be clogged and the surface of the spun fiber will be rough and defective.

[0083] In some of the examples, in the method for preparing graphene / PFA hybrid fibers, the melt spinning temperature is 360°C~400°C.

[0084] In some of the examples, in the method for preparing graphene / PFA hybrid fibers, the heat treatment temperature is 270°C~300°C.

[0085] One embodiment of the present application provides a polytetrafluoroethylene composite material, including the polytetrafluoroethylene composition described above or a polytetrafluoroethylene composition prepared by the method for preparing the polytetrafluoroethylene composition described above.

[0086] It can be understood that another embodiment of the present application provides a polytetrafluoroethylene composite material, including polytetrafluoroethylene, graphene and an anti-creep agent, and the mass ratio of graphene to polytetrafluoroethylene is (0.1~1):100.

[0087] In some of these examples, the PTFE composites consist of PTFE, graphene / PFA hybrid fibers, and modified polyphenylene sulfide.

[0088] One embodiment of the present application provides a method for preparing a polytetrafluoroethylene composite material, comprising the following steps:

[0089] The polytetrafluoroethylene composition or the polytetrafluoroethylene composition prepared by the method for preparing the polytetrafluoroethylene composition is subjected to molding treatment and sintering treatment in sequence to prepare a polytetrafluoroethylene composite material.

[0090] In some of the examples, in the method for preparing the polytetrafluoroethylene composite material, the forming process includes molding.

[0091] Optionally, the molding pressure is 40 MPa to 80 MPa, and the holding time is 20 min to 30 min.

[0092] In some examples, the method for preparing the polytetrafluoroethylene composite material further includes drying the polytetrafluoroethylene composition before the molding process. Optionally, the drying temperature is 130°C to 140°C.

[0093] In some of the examples, in the method for preparing the polytetrafluoroethylene composite material, the sintering temperature is 360°C~400°C.

[0094] It can be understood that the sintering temperature includes but is not limited to 360°C, 370°C, 380°C, 390°C, and 400°C.

[0095] Furthermore, the sintering time is 3 h~6 h.

[0096] It can be understood that in some examples, the temperature is raised at 50°C / min to 100°C / min to the sintering temperature and then maintained at that temperature; after the holding period, the temperature is cooled to room temperature at 30°C / min to 50°C / min.

[0097] One embodiment of the present application provides the use of the aforementioned polytetrafluoroethylene composition, the polytetrafluoroethylene composition prepared by the aforementioned method for preparing the polytetrafluoroethylene composition, the aforementioned polytetrafluoroethylene composite material, or the polytetrafluoroethylene composite material prepared by the aforementioned method for preparing the aforementioned polytetrafluoroethylene composite material in the preparation of sealing materials. Furthermore, the use of the aforementioned polytetrafluoroethylene composition, in particular, in reciprocating dynamic seals under medium- and high-pressure operating conditions, is provided.

[0098] One embodiment of the present application provides a sealing material, comprising the above-mentioned polytetrafluoroethylene composition, the polytetrafluoroethylene composition prepared by the above-mentioned method for preparing the polytetrafluoroethylene composition, the above-mentioned polytetrafluoroethylene composite material, or the polytetrafluoroethylene composite material prepared by the above-mentioned method for preparing the polytetrafluoroethylene composite material.

[0099] The polytetrafluoroethylene composition, the polytetrafluoroethylene composition prepared by the method for preparing the polytetrafluoroethylene composition, the polytetrafluoroethylene composite material, or the polytetrafluoroethylene composite material prepared by the method for preparing the polytetrafluoroethylene composite material are used to prepare sealing materials, which can effectively improve the compression creep resistance of the sealing component and extend its service life.

[0100] One embodiment of the present application provides a sealing member, comprising the above-mentioned sealing material.

[0101] The present application will be described in further detail below in conjunction with specific implementation methods, but the implementation methods of the present application are not limited thereto.

[0102] Example 1

[0103] (1) PFA and graphene were vacuum dried at 120 °C, mixed and granulated in a twin-screw extruder at a mass ratio of 50:3, and the extrudate was quenched in a room temperature water bath and then pulled into a pelletizer for slicing to obtain mixed slices. The mixed slices were completely dried at 120 °C and added to a spinning machine for melt spinning at a melt spinning temperature of 380 °C to obtain nascent fibers. The nascent fibers were hot stretched at 270 °C at a stretching speed of 5 m / min, and the fiber aspect ratio was controlled at about 10:1 using a shearing machine to obtain graphene / PFA hybrid fibers.

[0104] (2) Polytetrafluoroethylene, graphene / PFA hybrid fiber and modified polyphenylene sulfide (Torelina A515, the modifier is glass fiber and polytetrafluoroethylene) are added to a high-speed mixer in a mass ratio of 100:5:15, the speed is set to 3000 r / min, the mixing temperature is controlled below 15°C, and the mixture is uniformly mixed to obtain a mixture (i.e., a polytetrafluoroethylene composition, the mass ratio of graphene to polytetrafluoroethylene is 0.283:100); the mixture is placed in a 130°C oven for drying for 3 h, and then added to the mold of a molding machine, the pressure is set to 60 MPa, and the holding time is 30 min to obtain a modified polytetrafluoroethylene rod; the modified polytetrafluoroethylene rod is placed in a sintering furnace, the heating rate is set to 50°C / min, the temperature is raised to 360°C and kept for 3 h, and then cooled to room temperature at a rate of 30°C / min to obtain a polytetrafluoroethylene composite material.

[0105] Example 2

[0106] The method is basically the same as Example 1, except that step (1) is omitted, the graphene / PFA hybrid fiber in step (2) of Example 1 is replaced by graphene, and the amount of graphene added in Example 2 is the same as the graphene content in the polytetrafluoroethylene composition in Example 1, specifically as follows:

[0107] Polytetrafluoroethylene, graphene and modified polyphenylene sulfide (Torelina A515) were added to a high-speed mixer in a mass ratio of 100:0.283:15, the speed was set to 3000 r / min, the mixing temperature was controlled below 15°C, and the mixture was uniformly mixed to obtain a mixture (i.e., a polytetrafluoroethylene composition); the mixture was placed in a 130°C oven for drying for 3 h, and then added to the mold of a molding machine. The pressure was set to 60 MPa and the holding time was 30 min to obtain a modified polytetrafluoroethylene rod; the modified polytetrafluoroethylene rod was placed in a sintering furnace, the heating rate was set to 50°C / min, the temperature was raised to 360°C and kept for 3 h, and then cooled to room temperature at a rate of 30°C / min to obtain a polytetrafluoroethylene composite material.

[0108] Example 3

[0109] Polytetrafluoroethylene, graphene, PFA and modified polyphenylene sulfide (Torelina A515) were added to a high-speed mixer in a mass ratio of 100:0.283:4.717:15, the speed was set to 3000 r / min, the mixing temperature was controlled below 15°C, and the mixture was uniformly mixed to obtain a mixture (i.e., a polytetrafluoroethylene composition); the mixture was placed in a 130°C oven for drying for 3 h, and then added to the mold of a molding machine. The pressure was set to 60 MPa and the holding time was 30 min to obtain a modified polytetrafluoroethylene rod; the modified polytetrafluoroethylene rod was placed in a sintering furnace, the heating rate was set to 50°C / min, the temperature was raised to 360°C and kept for 3 h, and then cooled to room temperature at a rate of 30°C / min to obtain a polytetrafluoroethylene composite material.

[0110] Example 4

[0111] The process is basically the same as Example 1, except that the modified polyphenylene sulfide in step (2) of Example 1 is replaced by polyimide of equal mass.

[0112] Example 5

[0113] The process is basically the same as Example 1, except that the modified polyphenylene sulfide in step (2) of Example 1 is replaced by (unmodified) polyphenylene sulfide.

[0114] Example 6

[0115] (1) PFA and graphene were vacuum dried at 120 °C and then mixed and pelletized in a twin-screw extruder at a mass ratio of 50:3. The extrudate was quenched in a room temperature water bath and then pulled into a pelletizer for slicing to obtain graphene / PFA hybrid chips.

[0116] (2) Preparation and processing of polytetrafluoroethylene composition: polytetrafluoroethylene, graphene / PFA hybrid chips and modified polyphenylene sulfide (Torelina A515) were added to a high-speed mixer in a mass ratio of 100:5:15, the speed was set to 3000 r / min, the mixing temperature was controlled below 15 °C, and the mixture was uniformly mixed to obtain a mixture; the mixture was placed in a 130 °C oven for drying for 3 h, and then added to the mold of a molding machine, the pressure was set to 60 MPa, and the pressure holding time was 30 min to obtain a modified polytetrafluoroethylene rod; the modified polytetrafluoroethylene rod was placed in a sintering furnace, the heating rate was set to 50 °C / min, the temperature was raised to 360 °C and kept for 3 h, and then cooled to room temperature at a rate of 30 °C / min.

[0117] Example 7

[0118] The method is basically the same as Example 1, except that the mass ratio of graphene to polytetrafluoroethylene is 0.66:100, as follows:

[0119] (1) PFA and graphene were vacuum dried at 120 °C, mixed and granulated in a twin-screw extruder in a mass ratio of 46:7, and the extrudate was quenched in a room temperature water bath and then pulled into a pelletizer for slicing to obtain mixed slices. The mixed slices were completely dried at 120 °C and added to a spinning machine for melt spinning at a melt spinning temperature of 380 °C to obtain nascent fibers. The nascent fibers were hot stretched at 270 °C at a stretching speed of 5 m / min, and the fiber aspect ratio was controlled at about 10:1 using a shearing machine to obtain graphene / PFA hybrid fibers.

[0120] (2) Polytetrafluoroethylene, graphene / PFA hybrid fiber and modified polyphenylene sulfide (Torelina A515) were added to a high-speed mixer in a mass ratio of 100:5:15, the speed was set to 3000 r / min, the mixing temperature was controlled below 15°C, and the mixture was uniformly mixed to obtain a mixture (i.e., a polytetrafluoroethylene composition, with a mass ratio of graphene to polytetrafluoroethylene of 0.66:100); the mixture was placed in a 130°C oven for drying for 3 h, and then added to the mold of a molding machine, the pressure was set to 60 MPa, and the holding time was 30 min to obtain a modified polytetrafluoroethylene rod; the modified polytetrafluoroethylene rod was placed in a sintering furnace, the heating rate was set to 50°C / min, the temperature was raised to 360°C and kept for 3 h, and then cooled to room temperature at a rate of 30°C / min to obtain a polytetrafluoroethylene composite material.

[0121] Example 8

[0122] The method is basically the same as Example 1, except that in step (2), the mass ratio of polytetrafluoroethylene, graphene / PFA hybrid fiber and modified polyphenylene sulfide is 100:5:20.

[0123] Comparative Example 1

[0124] The polytetrafluoroethylene was placed in an oven at 130°C and dried for 3 h, then added to the mold of a molding machine, the pressure was set to 40 MPa, and the pressure was maintained for 20 min to produce polytetrafluoroethylene rods; the pure polytetrafluoroethylene rods were placed in a sintering furnace, the heating rate was set to 50°C / min, the temperature was raised to 360°C and kept for 3 h, and then cooled to room temperature at a rate of 30°C / min.

[0125] Comparative Example 2

[0126] The method is basically the same as Example 1, except that the graphene in step (1) of Example 1 is replaced with carbon fiber, as follows:

[0127] (1) PFA and carbon fiber were vacuum dried at 120 °C, mixed and pelletized in a twin-screw extruder at a mass ratio of 50:3, and the extrudate was quenched in a room temperature water bath and then pulled into a pelletizer for slicing to obtain mixed slices. The mixed slices were completely dried at 120 °C and added to a spinning machine for melt spinning at a melt spinning temperature of 380 °C to obtain spun fibers. The spun fibers were hot stretched at 270 °C at a stretching speed of 5 m / min, and the fiber aspect ratio was controlled at about 10:1 using a shearing machine to obtain carbon fiber / PFA hybrid fibers.

[0128] (2) Polytetrafluoroethylene, carbon fiber / PFA hybrid fiber and modified polyphenylene sulfide (Torelina A515) were added to a high-speed mixer in a mass ratio of 100:5:15, the speed was set to 3000 r / min, the mixing temperature was controlled below 15°C, and the mixture was uniformly mixed to obtain a mixture; the mixture was placed in a 130°C oven for drying for 3 h, and then added to the mold of a molding machine, the pressure was set to 60 MPa, and the holding time was 30 min to obtain a modified polytetrafluoroethylene rod; the modified polytetrafluoroethylene rod was placed in a sintering furnace, the heating rate was set to 50°C / min, the temperature was raised to 360°C and kept for 3 h, and then cooled to room temperature at a rate of 30°C / min to obtain a polytetrafluoroethylene composite material.

[0129] Comparative Example 3

[0130] Polytetrafluoroethylene, carbon fiber and modified polyphenylene sulfide (Torelina A515) were added to a high-speed mixer in a mass ratio of 100:0.283:15, the speed was set to 3000 r / min, the mixing temperature was controlled below 15°C, and the mixture was uniformly mixed to obtain a mixture; the mixture was placed in a 130°C oven for drying for 3 h, and then added to the mold of a molding machine, the pressure was set to 60 MPa, and the pressure was maintained for 30 min to obtain a modified polytetrafluoroethylene rod; the modified polytetrafluoroethylene rod was placed in a sintering furnace, the heating rate was set to 50°C / min, the temperature was raised to 360°C and maintained for 3 h, and then cooled to room temperature at a rate of 30°C / min to obtain a polytetrafluoroethylene composite material.

[0131] Comparative Example 4

[0132] The method is basically the same as Example 6, except that the mass ratio of graphene to polytetrafluoroethylene is 3:100, as follows:

[0133] (1) PFA and graphene were vacuum dried at 120 °C and then mixed and pelletized in a twin-screw extruder at a mass ratio of 50:3. The extrudate was quenched in a room temperature water bath and then pulled into a pelletizer for slicing to obtain graphene / PFA hybrid chips.

[0134] (2) Polytetrafluoroethylene, graphene / PFA hybrid chips and modified polyphenylene sulfide (Torelina A515) were added to a high-speed mixer in a mass ratio of 100:53:15, the speed was set to 3000 r / min, the mixing temperature was controlled below 15°C, and the mixture was uniformly mixed to obtain a mixture. The mass ratio of graphene to polytetrafluoroethylene in the mixture was 3:100; the mixture was placed in a 130°C oven for drying for 3 h, and then added to the mold of a molding machine, the pressure was set to 60 MPa, and the pressure holding time was 30 min to obtain modified polytetrafluoroethylene rods; the modified polytetrafluoroethylene rods were placed in a sintering furnace, the heating rate was set to 50°C / min, and the temperature was raised to 360°C for sintering.

[0135] The modified polytetrafluoroethylene rod prepared in Comparative Example 4 exhibited bulging during the sintering stage and could not be further processed into parts for performance characterization.

[0136] The commercially available creep-resistant polytetrafluoroethylene material has a modified filler of bronze powder, and the mass ratio of polytetrafluoroethylene to bronze powder is approximately 3:2.

[0137] Performance testing:

[0138] (1) Friction and wear performance

[0139] The friction coefficient of the composite material was determined by a ball-on-disc tribometer. The friction pair was a bearing steel ball with a diameter of 4 mm. The rotation linear speed was 200 r / min, the rotation radius was 3 mm, the time was 20 min, and the load was set to 2 N. The volume wear rate of the material after the friction test was determined by a three-dimensional white light interferometry profiler to characterize the wear resistance. The results are shown in Table 1.

[0140] Table 1

[0141]

[0142] As can be seen from Table 1, compared with Comparative Example 1 and commercially available polytetrafluoroethylene composite materials, the polytetrafluoroethylene composite materials prepared in each embodiment have a reduced volume wear rate while ensuring a reduced friction coefficient; while Comparative Examples 2 and 3 use carbon fiber as an inorganic filler, which improves wear resistance, but has a large friction coefficient, releases high friction heat during friction, easily causes material deformation, and has a high risk of carbon fiber falling off from the polytetrafluoroethylene matrix.

[0143] (2) Compression creep resistance

[0144] The compression creep curves of the composite materials were tested at 100°C using a creep tester. The load was set to 25 MPa and the test time was 48 hours. The results are as follows: Figure 1 shown.

[0145] from Figure 1 It can be seen that the deformation of the polytetrafluoroethylene composite materials provided by Examples 1 to 8 at 100°C and 25 MPa is lower than that of Comparative Example 1, among which the deformation of Examples 1 to 3, 5 and 7 to 8 is lower than that of the commercially available materials. In particular, the deformation of the polytetrafluoroethylene composite materials provided by Examples 1 and 7 to 8 is significantly reduced compared with Comparative Example 1, indicating that the present application can significantly improve the compressive creep resistance of the polytetrafluoroethylene composite material by combining polytetrafluoroethylene, graphene / PFA hybrid fiber and modified polyphenylene sulfide in appropriate proportions.

[0146] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0147] The embodiments described above only express several implementation methods of the present application, which are convenient for understanding the technical solutions of the present application in a specific and detailed manner, but they cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all fall within the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description can be used to interpret the content of the claims.

Claims

1. A polytetrafluoroethylene composition, characterized in that The invention comprises polytetrafluoroethylene, graphene and an anti-creep agent, wherein the mass ratio of the graphene to the polytetrafluoroethylene is (0.1-1):

100.

2. The polytetrafluoroethylene composition according to claim 1, wherein The mass ratio of the graphene to the polytetrafluoroethylene is (0.2-0.7):100; And / or, the mass ratio of the anti-creep agent to the polytetrafluoroethylene is (10-20):

100.

3. The polytetrafluoroethylene composition according to claim 1, wherein The anti-creep agent includes at least one of polyphenylene sulfide and polyimide.

4. The polytetrafluoroethylene composition according to claim 3, wherein The polyphenylene sulfide is modified polyphenylene sulfide, and the modifier of the modified polyphenylene sulfide includes glass fiber and polytetrafluoroethylene.

5. The polytetrafluoroethylene composition according to any one of claims 1 to 4, characterized in that The polytetrafluoroethylene composition further includes PFA, and the mass ratio of the PFA to the polytetrafluoroethylene is (4-10):

100.

6. The polytetrafluoroethylene composition according to claim 5, wherein The PFA and the graphene form graphene / PFA hybrid fibers, and in the graphene / PFA hybrid fibers, the PFA is coated on the surface of the graphene.

7. The polytetrafluoroethylene composition according to any one of claims 1 to 4 and 6, characterized in that: The specific surface area of ​​the graphene is 400 m 2 / g~600 m 2 / g; And / or, the average particle size of the graphene is 5 μm to 15 μm; And / or, the average particle size of the polytetrafluoroethylene is 15 μm to 25 μm; And / or, the bulk density of the polytetrafluoroethylene is 0.3 g / cm 3 ~1 g / cm 3 .

8. A method for preparing a polytetrafluoroethylene composition, characterized in that: The following steps are involved: Polytetrafluoroethylene, graphene and an anti-creep agent are mixed to prepare a polytetrafluoroethylene composition; the mass ratio of the graphene to the polytetrafluoroethylene is (0.1~1):

100.

9. The method for preparing the polytetrafluoroethylene composition according to claim 8, wherein: The polytetrafluoroethylene composition further includes PFA, and the PFA and the graphene form graphene / PFA hybrid fibers. The preparation of the graphene / PFA hybrid fibers includes the following steps: The PFA and the graphene are mixed and then granulated, sliced, melt-spun and heat-treated in sequence to prepare graphene / PFA hybrid fibers.

10. A polytetrafluoroethylene composite material, characterized in that: The invention relates to a polytetrafluoroethylene composition according to any one of claims 1 to 7 or a polytetrafluoroethylene composition prepared by the method for preparing the polytetrafluoroethylene composition according to any one of claims 8 to 9.

11. A method for preparing a polytetrafluoroethylene composite material, characterized in that: The following steps are involved: The polytetrafluoroethylene composition according to any one of claims 1 to 7 or the polytetrafluoroethylene composition prepared by the method for preparing the polytetrafluoroethylene composition according to any one of claims 8 to 9 is subjected to molding treatment and sintering treatment in sequence to prepare a polytetrafluoroethylene composite material.

12. A sealing material, characterized in that: The invention comprises the polytetrafluoroethylene composition according to any one of claims 1 to 7, the polytetrafluoroethylene composition prepared by the method for preparing the polytetrafluoroethylene composition according to any one of claims 8 to 9, the polytetrafluoroethylene composite material according to claim 10, or the polytetrafluoroethylene composite material prepared by the method for preparing the polytetrafluoroethylene composite material according to claim 11.

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