Polyetheretherketone with low shear viscosity and preparation method and application thereof

Abstract

The present application relates to polyetheretherketone (PEEK) with low shear viscosity, its preparation method, and application. Specifically, the PEEK satisfies the following properties: i) the PEEK has a repeating unit represented by the following formula (I): ii) the PEEK has a weight-average molecular weight in the range of 15,000 to 45,000, as determined by GPC; and iii) a nitrobenzoyloxy group is attached to the molecular chain end of the PEEK. This PEEK has a significantly lower shear viscosity at a specific melt flow rate. It is not only suitable for injection molding and molding applications, but also for the extrusion of sheets and rods, which are generally inapplicable to conventional PEEK with higher viscosity, as well as the preparation of prepregs, greatly expanding the application field of PEEK. #imgabs0#

Description

Technical Field

[0001] The present application belongs to the technical field of polymer materials and relates to a polyetheretherketone, and more specifically to a polyetheretherketone having a lower shear viscosity at a given melt flow rate, and a preparation method and application thereof. Background Art

[0002] Polyetheretherketone (PEEK) is a specialty engineering plastic first developed and commercialized by the British company ICI in the late 1970s, entering industrial production in 1987. Due to its exceptional comprehensive properties, including high heat resistance, radiation resistance, corrosion resistance, dimensional stability, and excellent electrical properties, this material has rapidly gained widespread application in industries such as defense, military, aerospace, electronics, petrochemicals, healthcare, and the automotive sector.

[0003] To meet the needs of my country's defense, military, aerospace, and electronic information industries, the State Science and Technology Commission recently designated the research and development of polyetheretherketone (PEEK) resins and secondary products as a key national scientific and technological project, included in the National Development Plan, and assigned to relevant domestic research institutes. After more than a decade of dedicated effort, the PEEK project has achieved significant technological breakthroughs, completing the experimental scale-up and in-depth research phases and achieving initial capacity for industrial production of PEEK.

[0004] The known synthesis technology for polyetheretherketone (PEEK) involves polymerization of 4,4'-difluorobenzophenone and hydroquinone as comonomers in the presence of an alkali metal salt using diphenyl sulfone as a solvent at high temperatures (above 300°C). The resulting PEEK product has a high shear viscosity at a specific melt index, making it suitable only for injection molding and compression molding. Due to its high viscosity, it is unsuitable for extrusion of sheets and rods, or for the preparation of prepregs. Summary of the Invention

[0005] The purpose of the present application is to provide a polyetheretherketone with lower shear viscosity at a given melt flow rate, which is suitable for use in the extrusion of plates and rods and the preparation of prepregs.

[0006] In one aspect of the present application, the present application provides a polyetheretherketone, which satisfies the following properties:

[0007] i) The polyetheretherketone has a repeating unit represented by the following formula (I):

[0008]

[0009] ii) the polyetheretherketone has a weight average molecular weight in the range of 15,000 to 45,000, as determined by GPC; and

[0010] iii) A nitrobenzoyloxy group is connected to the molecular chain end of the polyetheretherketone.

[0011] By controlling the weight-average molecular weight of polyetheretherketone within the above range and introducing a benzoyloxy group at the molecular weight end of polyetheretherketone, it is possible to ensure that polyetheretherketone has a significantly lower shear viscosity at a specific melt flow rate, thereby making the resulting polyetheretherketone product not only suitable for injection molding and molding applications, but also suitable for the extrusion of sheets and rods that conventional polyetheretherketone with higher viscosity is usually not applicable, as well as the preparation of prepregs, thereby greatly expanding the application field of polyetheretherketone.

[0012] In some embodiments according to the present application, the nitrobenzoyloxy group is selected from one or more of a 2-nitrobenzoyloxy group, a 3-nitrobenzoyloxy group, and a 4-nitrobenzoyl group.

[0013] In some embodiments according to the present application, the nitrobenzoyloxy group is derived from a compound containing a nitrobenzoyloxy group, and the compound containing a nitrobenzoyloxy group is selected from one or more of 2-nitrobenzoic acid, 3-nitrobenzoic acid, 4-nitro-benzoic acid, 2-nitrobenzoyl fluoride, 3-nitrobenzoyl fluoride, and 4-nitro-benzoyl fluoride.

[0014] In some embodiments according to the present application, the polyetheretherketone contains 0.7 wt%-2.2 wt%, preferably 0.7 wt% to 0.8 wt% of the nitrobenzoyloxy group, where the weight percentage of the nitrobenzoyloxy group is the weight percentage of the nitrobenzoyloxy segment in the formed polyetheretherketone molecule.

[0015] By controlling the weight percentage of nitrobenzoyloxy groups attached to the ends of the polyetheretherketone molecular chains within the aforementioned range, the resulting polyetheretherketone can be guaranteed to have an appropriate molecular weight, which is beneficial for maintaining appropriate mechanical properties. Furthermore, the shear properties of the resulting polyetheretherketone can be significantly improved, resulting in a significantly lower shear viscosity at a specific melt flow rate. The inventors of the present invention surprisingly discovered that polyetheretherketones of the same molecular weight that are terminated with nitro groups have lower shear viscosity than those that are not terminated with nitro groups, a finding that was not anticipated prior to the present application.

[0016] In some specific embodiments of the present application, the polyetheretherketone has a structural formula shown in any one of the following formulas (II-1) to (II-3):

[0017]

[0018] Here, n is a positive integer in the range of 50 to 200.

[0019] In some embodiments according to the present application, when the polyetheretherketone has a melt index of 10 g / min-12 g / 10 min at 380°C, it has a melt index of 10 g / min-12 g / 10 min at 400°C, 1000 -1 The shear viscosity at S is not more than 450 Pa·S, preferably not more than 430 Pa·S, more preferably not more than 405 Pa·S, the melt index is measured according to GB / T-3682, and the shear viscosity is measured according to GB / T 25278-2010.

[0020] In other embodiments according to the present application, the polyetheretherketone has a shear viscosity reduction of at least 10%, preferably at least 12%, more preferably at least 17%, compared to a polyetheretherketone having substantially the same melt index and not capped with nitrobenzoyloxy groups, wherein the shear viscosity is reduced at 400°C, 1000°C, -1 The S value is determined according to GB / T 25278-2010.

[0021] Another aspect of the present application provides a method for preparing the above-mentioned polyetheretherketone, which comprises the following steps: under an inert atmosphere and in the presence of an alkali metal carbonate, subjecting 4,4'-difluorobenzophenone and hydroquinone to nucleophilic condensation, and then, during the process of the nucleophilic condensation, adding a nitrobenzoyloxy-containing compound to the reaction system of the nucleophilic condensation to continue the reaction; and after the reaction is completed, cooling and purifying to obtain the polyetheretherketone.

[0022] In some embodiments according to the present application, the alkali metal carbonate includes sodium carbonate or a mixture of sodium carbonate and potassium carbonate, preferably includes a mixture of sodium carbonate and potassium carbonate, and the molar ratio of the two is in the range of 8.5-9.5:1.

[0023] In some embodiments according to the present application, the molar ratio of the alkali metal carbonate to the hydroquinone is in the range of 1.001-1.15:1, optionally in the range of 1.001-1.005:1.

[0024] In some embodiments according to the present application, the molar ratio of the 4,4'-difluorobenzophenone to the hydroquinone is in the range of 1.001-1.04:1, optionally in the range of 1.001-1.005:1.

[0025] In some embodiments according to the present application, the molar ratio of the compound containing a nitrobenzoyloxy group to the 4,4'-difluorobenzophenone is in the range of 0.095-0.105:1, optionally in the range of 0.099-1.001:1.

[0026] In some embodiments of the present application, during the nucleophilic polycondensation, the temperature is first raised to 220° C. and maintained for 60-70 minutes; the temperature is then raised to 280° C.; after the nitrobenzoyloxy-containing compound is added, the temperature is then raised to 320° C. and maintained for 50-60 minutes.

[0027] In some embodiments according to the present application, during the nucleophilic polycondensation, an aromatic sulfone is used as a solvent, and the aromatic sulfone is selected from one or more of diphenyl sulfone, dibenzothiophene dioxide, phenoxathiophene dioxide and 4-phenylsulfonylbiphenyl. Preferably, the weight of the solvent is 3 times or more, but not more than 10 times, the weight of 4,4'-difluorobenzophenone.

[0028] A third aspect of the present application provides a plate, which is formed by extruding the polyetheretherketone according to the first aspect of the present application or the polyetheretherketone prepared by the method according to the second aspect of the present application.

[0029] A fourth aspect of the present application provides a pipe formed by extruding the polyetheretherketone according to the first aspect of the present application or the polyetheretherketone prepared by the method according to the second aspect of the present application.

[0030] A fifth aspect of the present application provides a prepreg prepared from the polyetheretherketone according to the first aspect of the present application or the polyetheretherketone prepared by the method according to the second aspect of the present application.

[0031] The plates, tubes and prepregs of the present application contain the polyetheretherketone provided by the present application, and thus have at least the same advantages as the polyetheretherketone. DETAILED DESCRIPTION

[0032] The following description will be described in detail, as appropriate, to specifically disclose embodiments of the polyetheretherketone (PEEK) of the present application, its preparation method, and related applications. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially identical structures may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Furthermore, the following description is provided to enable those skilled in the art to fully understand the present application and is not intended to limit the subject matter described in the claims.

[0033] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0034] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0035] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of this application.

[0036] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0037] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0038] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0039] Unless otherwise specified, in this application, the terms "first", "second", "third", etc. are used to distinguish different objects rather than to describe a specific order or a primary-secondary relationship.

[0040] In this application, the terms "plurality", "multiple" and the like refer to two or more.

[0041] Unless otherwise specified, the terms used in this application have the common meanings that are commonly understood by those skilled in the art.

[0042] Unless otherwise specified, the values ​​of the various parameters mentioned in this application can be measured using various test methods commonly used in the art, for example, they can be measured according to the test methods given in the examples of this application. Unless otherwise specified, the test temperature is 25°C.

[0043] In the context of this application, the term "nitrobenzoyloxy" may be optionally substituted.

[0044] When the above groups (eg, nitrobenzoyloxy) are described as being substituted, the substituent groups may include halogen atoms or heteroatoms.

[0045] The term "halogen atom" includes a fluorine atom, a chlorine atom, a bromine atom and the like.

[0046] The term "heteroatom" includes a nitrogen atom, a sulfur atom, a phosphorus atom and the like.

[0047] Since its introduction, polyetheretherketone (PEEK) has been widely used in industries such as defense, military, aerospace, electronics, petrochemicals, healthcare, and the automotive industry due to its excellent overall properties, including high heat resistance, radiation resistance, corrosion resistance, good dimensional stability, and superior electrical properties. The known synthesis technology for PEEK involves polymerization of 4,4'-difluorobenzophenone and hydroquinone as comonomers in the presence of an alkali metal salt using diphenyl sulfone as a solvent at high temperatures (above 300°C). The resulting PEEK product has a high shear viscosity at a specific melt index, making it suitable only for applications such as injection molding and compression molding. Due to its high viscosity, it is unsuitable for extrusion of sheets and rods or the preparation of prepregs.

[0048] In order to solve the above problems, the inventors of the present application conducted a large number of experiments and in-depth research, and surprisingly found that the introduction of nitro groups into the molecular chain of polyetheretherketone polymer can achieve significantly lower shear viscosity at a given melt index of polyetheretherketone. The resulting polyetheretherketone has appropriate mechanical strength and is not only suitable for injection molding and molding applications, but also suitable for the extrusion of sheets and rods with higher viscosity that conventional polyetheretherketone cannot usually be used for, as well as the preparation of prepregs, which greatly expands the application field of polyetheretherketone.

[0049] Therefore, a first aspect of the embodiments of the present application provides a polyetheretherketone, which satisfies the following properties:

[0050] i) The polyetheretherketone has a repeating unit represented by the following formula (I):

[0051]

[0052] ii) the polyetheretherketone has a weight average molecular weight in the range of 15,000 to 45,000, as determined by GPC; and

[0053] iii) A nitrobenzoyloxy group is connected to the molecular chain end of the polyetheretherketone.

[0054] In this article, the term "weight average molecular weight" has a well-known meaning in the field of polymer materials, and it can be measured by instruments and methods known in the art. As an exemplary illustration, for example, gel chromatography is used for testing, such as taking 20 mg of PEEK (polyetheretherketone) sample and placing it in a 10 ml cillin bottle, adding 3.15 ml of α-chloronaphthalene with a pipette, and placing it on an oscillator at 150 degrees Celsius for 1.5 hours. The sample is completely dissolved in α-chloronaphthalene, and after cooling, 4.20 ml of 1,2,4-trichlorobenzene is added to the cillin bottle, shaken evenly, 2 ml of sample is taken from the cillin bottle with a filter pipette and added to an ampoule, which is sealed with an aluminum cap, and the ampoule is placed on a PL-220 gel chromatograph (GPC) sample tray. At a column temperature of 115 degrees Celsius and a mobile phase of 1 ml / min, the injection volume is 200 μl, the k value is taken as 14.1, and the Alpha value is taken as 0.7, the weight average molecular weight of the sample is measured.

[0055] In an embodiment of the present application, the weight average molecular weight of the polyetheretherketone is in the range of 15,000 to 45,000, optionally in the range of 20,000 to 45,000, and more optionally in the range of 25,000 to 45,000. For example, the weight average molecular weight of the polyetheretherketone can be 20,000, 21,000, 22,000, 23,000, 24,000, 25,000, 26,000, 27,000, 28,000, 29,000, 30,000, 31,000, 32,000, 33,000, 34,000, 35,000, 36,000, 37,000, 38,000, 39,000, 40,000, 41,000, 42,000, 43,000, 44,000, or 45,000, or a range formed by any two of the foregoing values. When the weight average molecular weight of the polyetheretherketone is within the foregoing range, the obtained polyetheretherketone has appropriate mechanical strength, which is conducive to forming sheets and pipes with excellent performance.

[0056] In an embodiment of the present application, the polyetheretherketone (PEK) has a nitrobenzoyloxy group attached to the end of its molecular chain. As described above, the inventors of the present application have discovered that by introducing a nitrobenzoyloxy group into the molecular chain of the PEEK polymer, a significantly lower shear viscosity can be achieved at a given PEEK melt index. The resulting PEEK has suitable mechanical strength and is suitable not only for injection molding and compression molding, but also for the extrusion of sheets and rods, which are typically inapplicable to conventional PEEK with higher viscosity, as well as the preparation of prepregs. This greatly expands the application areas of PEEK.

[0057] In the present application, the molecular chain of the polyetheretherketone is terminated with nitrobenzoyloxy, which is a nitration product obtained by a nucleophilic reaction. The nucleophilic reaction according to the present application is different from the traditional nitration reaction (i.e., the reaction of dehydrating polyetheretherketone with concentrated nitric acid and concentrated sulfuric acid), in that a nitro compound is used to graft the entire nitro compound onto the polyetheretherketone molecular chain, and the nitro group is not transferred during the reaction. In comparison, the traditional nitration reaction is to transfer the nitro group of nitric acid to the benzene ring of polyetheretherketone, replacing the position of "hydrogen" on the benzene ring. The method of modifying polyetheretherketone using a nucleophilic reaction not only results in a significant difference in structure of the nitro-modified polyetheretherketone formed compared to the traditional nitration method, but also has obvious cost and environmental advantages, avoids the increase in equipment cost due to the use of nitric acid / sulfuric acid, and reduces the environmental risks and pollution due to the use of nitric acid / sulfuric acid.

[0058] In some embodiments of the present application, the nitrobenzoyloxy group is selected from one or more of a 2-nitrobenzoyloxy group, a 3-nitrobenzoyloxy group, and a 4-nitrobenzoyl group. The nitrobenzoyloxy group may be derived from a compound containing a nitrobenzoyloxy group. In the present application, a "compound containing a nitrobenzoyloxy group" refers to a compound having a nitrobenzoyloxy group as a portion of the molecule and having a reactive reaction with a comonomer used to prepare polyetheretherketone, including but not limited to 4,4'-difluorobenzophenone and hydroquinone. As an exemplary illustration, the compound containing a nitrobenzoyloxy group is selected from one or more of 2-nitrobenzoic acid, 3-nitrobenzoic acid, 4-nitro-benzoic acid, 2-nitrobenzoyl fluoride, 3-nitrobenzoyl fluoride and 4-nitro-benzoyl fluoride; preferably selected from one or more of 2-nitrobenzoic acid, 3-nitrobenzoic acid and 4-nitro-benzoic acid; more preferably selected from one or more of 2-nitrobenzoic acid and 4-nitro-benzoic acid; most preferably selected from 4-nitro-benzoic acid.

[0059] In some embodiments according to the present application, the polyetheretherketone contains 0.7 wt%-2.2 wt%, preferably 0.7 wt% to 0.8 wt% of the nitrobenzoyloxy group, where the weight percentage of the nitrobenzoyloxy group is the weight percentage of the nitrobenzoyloxy segment in the formed polyetheretherketone molecule.

[0060] By controlling the weight percentage of nitrobenzoyloxy groups attached to the ends of the polyetheretherketone molecular chains within the aforementioned range, the resulting polyetheretherketone can be guaranteed to have an appropriate molecular weight, which is beneficial for maintaining appropriate mechanical properties. Furthermore, the shear properties of the resulting polyetheretherketone can be significantly improved, resulting in a significantly lower shear viscosity at a specific melt flow rate. The inventors of the present invention surprisingly discovered that polyetheretherketones of the same molecular weight that are end-capped with nitro groups have lower shear viscosity than those that are not end-capped with nitro groups, a finding that was not anticipated prior to the present application.

[0061] In the present application, the end groups of polyetheretherketone can be determined using any instrument and equipment known in the art. As an exemplary illustration, the end groups of polyetheretherketone are determined using a nuclear magnetic resonance spectrometer (NMR). The specific test method is to take 10 mg of the prepared polyetheretherketone sample, dissolve it in 10 ml of deuterated trifluoroacetic acid at 60°C, and add 10 ml of deuterated trifluoroacetic acid after dissolution to prevent crystallization. If polyetheretherketone cannot be dissolved in hot deuterated trifluoroacetic acid, it means that the end groups of the polyetheretherketone are prepared by a traditional method, and are polyetheretherketones with fluorine or hydroxyl as end groups; if polyetheretherketone can be dissolved in hot deuterated trifluoroacetic acid, it means that the end groups of the polyetheretherketone may be sulfonic acid groups, nitro groups, nitroso groups, hydroxylamine groups, carboxyl groups, ester groups and aldehyde groups. The specific group types need to be determined by NMR test analysis. Adjust the NMR to a specific test temperature, wait for a while until the internal temperature of the NMR stabilizes near the set value, place the sample to be tested in the NMR, and wait for a while until the sample reaches the same temperature as the inside of the NMR; open the parameter setting interface of the nuclear magnetic resonance spectrometer, adjust the parameter values, and observe the changes in the spectrum until the optimal signal-to-noise ratio and resolution are achieved; after the instrument is adjusted, place the sample in the sample chamber, start the NMR, select the appropriate scanning mode and parameters, start collecting signals, wait for the signal collection to be completed, save the data, and perform subsequent data processing and analysis as needed.

[0062] In some specific embodiments of the present application, the polyetheretherketone has a structural formula shown in any one of the following formulas (II-1) to (II-3):

[0063]

[0064] Here, n is a positive integer in the range of 50 to 200.

[0065] In some embodiments according to the present application, when the polyetheretherketone has a melt index of 10 g / min-12 g / 10 min at 380°C, it has a melt index of 10 g / min-12 g / 10 min at 400°C, 1000 -1 The shear viscosity at S is not more than 450 Pa·S, preferably not more than 430 Pa·S, more preferably not more than 405 Pa·S, the melt index is measured according to GB / T-3682, and the shear viscosity is measured according to GB / T 25278-2010.

[0066] In this article, the melt index is a parameter that characterizes the processing fluidity of a material. Generally, the higher the melt index, the better the processing fluidity of the material; the smaller the melt index, the worse the processing fluidity of the material. In general, a certain melt index corresponds to a certain shear viscosity. The inventors of this application have found that the polyetheretherketone according to the present invention can have a significantly lower shear viscosity at a certain melt index. For example, when the polyetheretherketone has a melt index of 10g / min-12g / 10min at 380°C, it has a significantly lower shear viscosity at 400°C, 1000°C, and 1000°C. -1 The shear viscosity at 1000 s is not more than 450 Pa·s, preferably not more than 430 Pa·s, more preferably not more than 405 Pa·s, the melt index is measured according to GB / T-3682, and the shear viscosity is measured according to GB / T 25278-2010. For example, when the polyetheretherketone has a melt index of 10 g / min-12 g / 10 min at 380°C, the polyetheretherketone has a melt index of 10 g / min-12 g / 10 min at 400°C, 1000 s, and 1000 s. -1 The shear viscosity at S may be no more than 430 Pa·s, no more than 425 Pa·s, no more than 420 Pa·s, no more than 415 Pa·s, no more than 410 Pa·s, no more than 405 Pa·s, no more than 400 Pa·s, no more than 395 Pa·s, no more than 390 Pa·s, no more than 385 Pa·s, no more than 380 Pa·s, no more than 375 Pa·s, no more than 370 Pa·s, no more than 365 Pa·s, no more than 360 Pa·s, no more than 355 Pa·s, but not less than 300 Pa·s, not less than 305 Pa·s, not less than 310 Pa·s, not less than 315 Pa·s, not less than 320 Pa·s, not less than 325 Pa·s, not less than 330 Pa·s, not less than 340 Pa·s, not less than 350 Pa·s, or a range formed by any two of the above values. When the polyetheretherketone has a melt index of 10g / min-12g / 10min at 380°C and the shear viscosity of the polyetheretherketone is within the above range, the obtained polyetheretherketone is suitable for the extrusion of plates and rods that conventional polyetheretherketone with higher viscosity is usually not applicable, as well as the preparation of prepregs, which greatly expands the application field of polyetheretherketone.

[0067] In other embodiments according to the present application, the polyetheretherketone has a shear viscosity reduction of at least 10%, preferably at least 12%, more preferably at least 17%, compared to a polyetheretherketone having substantially the same melt index and not capped with nitrobenzoyloxy groups, wherein the shear viscosity is reduced at 400°C, 1000°C, -1 The S value is determined according to GB / T 25278-2010.

[0068] In the context of this application, the expression "having substantially the same melt index" refers to two different polyetheretherketones. When the difference between the melt indexes of the two different polyetheretherketones is within the range of ±6%, the two different polyetheretherketones are considered to have substantially the same melt index. For example, when the melt indexes of polyetheretherketone A and polyetheretherketone B are measured under the same conditions, the difference between the obtained melt index a and the obtained melt index b is within the range of 6% or less relative to the percentage of the larger melt index of the melt index a and the melt index b. In this case, polyetheretherketone A and polyetheretherketone B are considered to have substantially the same melt index.

[0069] In the context of this application, the term "shear viscosity reduction" is used to measure the degree of reduction in shear viscosity of different polyetheretherketones with substantially the same melt index. The greater the shear viscosity reduction, the better the performance of the polyetheretherketone and the more suitable it is for use in the extrusion of sheets, rods, and the preparation of prepregs. The shear viscosity reduction is determined as follows: the shear viscosity of the polyetheretherketone terminated with nitrobenzoyloxy groups according to the present invention is measured; the shear viscosity of a polyetheretherketone with substantially the same melt index that is not terminated with nitrobenzoyloxy groups (i.e., a control polyetheretherketone) is measured, preferably, the raw materials, the amounts used, and the preparation method of the control polyetheretherketone are the same as those of the polyetheretherketone terminated with nitrobenzoyloxy groups according to the present invention, except that no nitrobenzoyloxy-containing compound is added; and the difference in shear viscosity is divided by the shear viscosity of the control polyetheretherketone to obtain the shear viscosity reduction.

[0070] The inventors of the present application have found that the polyetheretherketone according to the present invention has a significant reduction in shear viscosity compared to a polyetheretherketone having substantially the same melt index and not capped with nitrobenzoyloxy groups. For example, the polyetheretherketone according to the present invention has a shear viscosity reduction of at least 10%, preferably at least 12%, and more preferably at least 17%, at a temperature of 400°C, 1000°C, and 1500°F. -1 The viscosity of the polyetheretherketone according to the present invention is measured in accordance with GB / T 25278-2010 at 40°C. For example, the polyetheretherketone according to the present invention has a shear viscosity reduction of at least 13%, at least 14%, at least 15%, at least 16%, at least 17%, at least 18%, at least 19%, at least 20%, at least 21%, at least 22%, at least 23%, at least 24%, at least 25%, or more. When the polyetheretherketone according to the present invention has such a reduction in shear viscosity compared to a polyetheretherketone having substantially the same melt index but not capped with nitrobenzoyloxy groups, the resulting polyetheretherketone is suitable for extrusion of sheets and rods, as well as for the preparation of prepregs, where conventional polyetheretherketones with higher viscosities are generally inapplicable, thereby greatly expanding the application areas of the polyetheretherketone.

[0071] In this application, melt index has a meaning well known in the art and can be measured using any instrument and method known in the art. In this application, the melt index is measured using a melt flow rate meter according to GB / T-3682, with the instrument temperature set to 380°C, the weight mass being 5kg, and the cutting time being set to 60s. The specific operation is as follows: take 5g of the measured polyetheretherketone sample and add it to the test barrel of the melt flow rate meter. After waiting for 5 minutes for the temperature of the blocked polyetheretherketone to reach 380°C, press the test sample with a press rod, place the test weight, wait for the instrument to automatically cut the material, take the cut material segment and weigh the mass with a precision balance, input the mass number into the instrument, and calculate the melt index.

[0072] In this application, shear viscosity has a meaning known in the art and can be measured using any instrument and method known in the art. In this application, the shear viscosity test method is to use a capillary rheometer to test, according to the national standard GB / T 25278-2010, the instrument temperature is set to 400 ° C, 10g of blocked polyetheretherketone is added to the instrument barrel, wait for 5 minutes, start the instrument test, and take the test result as 1000 -1 Shear viscosity at S.

[0073] Another aspect of the present application provides a method for preparing the above-mentioned polyetheretherketone, which comprises the following steps: under an inert atmosphere and in the presence of an alkali metal carbonate, subjecting 4,4'-difluorobenzophenone and hydroquinone to nucleophilic condensation, and then, during the process of the nucleophilic condensation, adding a nitrobenzoyloxy-containing compound to the reaction system of the nucleophilic condensation to continue the reaction; and after the reaction is completed, cooling and purifying to obtain the polyetheretherketone.

[0074] In some embodiments according to the present application, the alkali metal carbonate includes sodium carbonate or a mixture of sodium carbonate and potassium carbonate, preferably includes a mixture of sodium carbonate and potassium carbonate, and the molar ratio of the two is in the range of 8.5-9.5:1.

[0075] In some embodiments according to the present application, the molar ratio of the alkali metal carbonate to the hydroquinone is in the range of 1.001-1.15:1, optionally in the range of 1.001-1.005:1.

[0076] In some embodiments according to the present application, the molar ratio of the 4,4'-difluorobenzophenone to the hydroquinone is in the range of 1.001-1.04:1, optionally in the range of 1.001-1.005:1.

[0077] In some embodiments according to the present application, the molar ratio of the compound containing a nitrobenzoyloxy group to the 4,4'-difluorobenzophenone is in the range of 0.095-0.105:1, optionally in the range of 0.099-1.001:1.

[0078] In some embodiments of the present application, during the nucleophilic polycondensation, the temperature is first raised to 220° C. and maintained for 60-70 minutes; the temperature is then raised to 280° C.; after the nitrobenzoyloxy-containing compound is added, the temperature is then raised to 320° C. and maintained for 50-60 minutes.

[0079] In some embodiments of the present application, during the nucleophilic polycondensation, an aromatic sulfone is used as a solvent, wherein the aromatic sulfone is selected from one or more of diphenyl sulfone, dibenzothiophene dioxide, thiophene dioxide, and 4-phenylsulfonylbiphenyl. Preferably, the weight of the solvent is 3 times or more, but not more than 10 times, the weight of 4,4'-difluorobenzophenone. Controlling the weight of the solvent within the above range can ensure that the viscosity of the reaction system is within an appropriate range while avoiding environmental pollution and increased costs caused by excessive solvent.

[0080] The above-mentioned method for preparing polyetheretherketone is carried out by a nucleophilic reaction. The nucleophilic reaction according to the present application is different from the traditional nitration reaction (i.e., the reaction of dehydrating polyetheretherketone using concentrated nitric acid and concentrated sulfuric acid), which uses a nitro compound to graft the entire nitro compound onto the polyetheretherketone molecular chain, and the nitro group does not transfer during the reaction. In comparison, the traditional nitration reaction is to transfer the nitro group of nitric acid to the benzene ring of polyetheretherketone, replacing the position of "hydrogen" on the benzene ring. The method of modifying polyetheretherketone using a nucleophilic reaction has obvious cost and environmental advantages compared to the traditional nitration method, avoids the increase in equipment cost due to the use of nitric acid / sulfuric acid, and reduces the environmental risks and pollution caused by the use of nitric acid / sulfuric acid.

[0081] The third aspect of the present application provides a sheet material formed by extruding the polyetheretherketone according to the first aspect of the present application or the polyetheretherketone prepared by the method according to the second aspect of the present application. In the context of the present application, the term "sheet material" refers to a flat rectangular article formed by extrusion, particularly melt extrusion.

[0082] The fourth aspect of the present application provides a pipe formed by extruding the polyetheretherketone according to the first aspect of the present application or the polyetheretherketone prepared by the method according to the second aspect of the present application. In the context of the present application, the term "pipe" refers to an article having an elongated tubular structure formed by extrusion, particularly melt extrusion.

[0083] The fifth aspect of the present application provides a prepreg, which is prepared from the polyetheretherketone according to the first aspect of the present application or the polyetheretherketone prepared by the method according to the second aspect of the present application. In the context of the present application, the term "prepreg" refers to a resin matrix impregnated with continuous fibers or fabrics as reinforcements and a composite material, which is an intermediate material for manufacturing composite materials.

[0084] The polyetheretherketone material of the present application has significantly lower shear viscosity, can remain in a molten state for a long time, has very little change in melt index, and has good mechanical properties and flow characteristics. It can be processed to manufacture extruded rods, plates and prepregs.

[0085] Compared with the existing PEEK, the polyetheretherketone material of this application has the following advantages:

[0086] (1) It has thermal stability and can remain in a molten state for a long time during processing, and its viscosity changes very little, making it easy to process;

[0087] (2) It has good mechanical properties and fluidity, and can be processed into intermediate products such as PEEK films, rods, plates, and pipes. In addition to being processed by injection molding and compression molding, it can also be processed by extrusion and is suitable for preparing prepregs.

[0088] Example

[0089] The following examples describe the present disclosure in more detail. These examples are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing. The instruments used in the examples are commercially available.

[0090] Test method:

[0091] 1) Weight average molecular weight: The weight average molecular weight of the polyetheretherketone prepared according to the examples and comparative examples of the present invention is measured based on gel chromatography using a PL-220 gel chromatograph (GPC);

[0092] 2) Confirmation of the nitrobenzoyloxy terminal group: The nitrobenzoyloxy terminal group at the molecular chain end of the polyetheretherketone prepared according to the examples and comparative examples of the present invention was confirmed by NMR;

[0093] 3) Melt Index: The melt index of the polyetheretherketone prepared according to the examples and comparative examples of the present invention was measured using a melt flow rate meter according to GB / T-3682, with the instrument temperature set at 380° C., a weight of 5 kg, and a cutting time set at 60 s.

[0094] 4) Shear viscosity: The shear viscosity of the polyetheretherketone prepared in the examples and comparative examples of the present invention was tested using a capillary rheometer. According to the national standard GB / T 25278-2010, the instrument temperature was set to 400°C, 10g of blocked polyetheretherketone was added to the instrument barrel, and after waiting for 5 minutes, the instrument was started for testing, and the test results were taken as 1000. -1 Shear viscosity at S.

[0095] Example 1:

[0096] Add 218.2g (1 mol) of 4,4'-difluorobenzophenone, 110.1g (1 mol) of hydroquinone, and 106g (1 mol) of sodium carbonate to a three-necked flask, introduce argon at a flow rate of 150ml / min, heat the three-necked flask, and after the materials in the flask are melted, stir at a speed of 60rpm. When the temperature rises to 220℃, maintain the constant temperature for one hour, continue heating to 280℃, add 16.7g (0.1mol) of 4-nitrobenzoic acid, raise the temperature and continue the reaction to 320℃, maintain for 50min, and obtain a viscous polyetheretherketone semi-finished product mixture. The reaction is complete. Pour the mixture into an iron plate while hot, crush it after cooling, wash it with appropriate amount of ethanol 5 times, wash it with distilled water 5 times, and dry it at 150℃ for 6 hours to obtain blocked polyetheretherketone. Test the weight average molecular weight, melt index and shear viscosity of the obtained sample. The blocked polyetheretherketone is soluble in hot 1,3,5-trichlorobenzene and has nitrobenzoyloxy terminal groups as shown by NMR analysis.

[0097] Example 2:

[0098] To a three-necked flask, add 218.2g (1 mol) of 4,4'-difluorobenzophenone, 110.1g (1 mol) of hydroquinone, 95.4g (0.9 mol) of sodium carbonate, and 13.8g (0.1 mol) of potassium carbonate. Argon is introduced at a flow rate of 150ml / min. The flask is heated. Once the contents are melted, stir at 60rpm. The temperature is raised to 220°C and maintained constant for one hour. Heating is continued to 280°C, and 16.7g (0.1 mol) of 4-nitrobenzoic acid is added. The temperature is raised to 320°C and the reaction is maintained for 50 minutes to obtain a viscous polyetheretherketone (PEEK) semi-finished product mixture. The reaction is complete. While hot, the mixture is poured into an iron pan, cooled, and crushed. The mixture is washed five times with appropriate amounts of ethanol and five times with distilled water, and then dried at 150°C for six hours to obtain the capped PEEK. The weight-average molecular weight, melt index, and shear viscosity of the resulting sample are measured. The blocked polyetheretherketone is soluble in hot 1,3,5-trichlorobenzene and has nitrobenzoyloxy terminal groups as shown by NMR analysis.

[0099] Example 3:

[0100] To a three-necked flask, add 218.2g (1 mol) of 4,4'-difluorobenzophenone, 110.1g (1 mol) of hydroquinone, 95.4g (0.9 mol) of sodium carbonate, and 13.8g (0.1 mol) of potassium carbonate. Argon is introduced at a flow rate of 150ml / min. The flask is heated. Once the contents are melted, stir at 60rpm. The temperature is raised to 220°C and maintained for one hour. Heating is then continued to 280°C. 16.7g (0.1 mol) of 2-nitrobenzoic acid is added, and the temperature is raised to 320°C and held for 50 minutes to obtain a viscous polyetheretherketone (PEEK) semi-finished product mixture. The reaction is complete. While hot, the mixture is poured into an iron pan, cooled, and crushed. The mixture is washed five times with appropriate amounts of ethanol and five times with distilled water, and then dried at 150°C for six hours to obtain the capped PEEK. The weight-average molecular weight, melt index, and shear viscosity of the resulting sample are measured. The blocked polyetheretherketone is soluble in hot 1,3,5-trichlorobenzene and has nitrobenzoyloxy terminal groups as shown by NMR analysis.

[0101] Example 4:

[0102] To a three-necked flask, add 218.2g (1 mol) of 4,4'-difluorobenzophenone, 110.1g (1 mol) of hydroquinone, 95.4g of sodium carbonate (0.9 mol), and 13.8g (0.1 mol) of potassium carbonate. Argon is introduced at a flow rate of 150ml / min. The flask is heated. Once the contents are melted, stir at 60rpm. The temperature is raised to 220°C and maintained constant for one hour. The mixture is then heated to 280°C and 16.7g (0.1 mol) of 3-nitrobenzoic acid is added. The temperature is raised to 320°C and the reaction is maintained for 50 minutes to obtain a viscous polyetheretherketone (PEEK) semi-finished product mixture. The reaction is complete. While hot, the mixture is poured into an iron pan, cooled, and crushed. The mixture is washed five times with appropriate amounts of ethanol and five times with distilled water, and then dried at 150°C for six hours to obtain the capped PEEK. The weight-average molecular weight, melt index, and shear viscosity of the resulting sample are measured. The blocked polyetheretherketone is soluble in hot 1,3,5-trichlorobenzene and has nitrobenzoyloxy terminal groups as shown by NMR analysis.

[0103] Comparative Example 1:

[0104] Add 218.2g (1mol) of 4,4'-difluorobenzophenone, 110.1g (1mol) of hydroquinone, and 106g (1mol) of sodium carbonate to a three-necked flask, introduce argon at a flow rate of 150ml / min, heat the three-necked flask, and stir at 60rpm after the material in the flask is melted. When the temperature rises to 220℃, maintain the constant temperature for one hour, continue heating to 320℃, react for a period of time, and obtain a viscous polyetheretherketone semi-finished product mixture. The reaction is completed. Pour the mixture into an iron plate while hot, crush it after cooling, wash it with appropriate amount of ethanol 5 times, wash it with distilled water 5 times, and dry it at 150℃ for 6 hours to obtain polyetheretherketone. Test the weight average molecular weight, melt index and shear viscosity of the obtained sample.

[0105] Comparative Example 2:

[0106] Add 218.2g (1 mol) of 4,4'-difluorobenzophenone, 110.1g (1 mol) of hydroquinone, 95.4g (0.9 mol) of sodium carbonate and 13.8g (0.1 mol) of potassium carbonate to a three-necked flask, introduce argon at a flow rate of 150ml / min, heat the three-necked flask, and after the material in the flask is melted, stir at a speed of 60rpm. When the temperature rises to 220℃, maintain the constant temperature for one hour, continue heating to 320℃, react for a period of time, and obtain a viscous polyetheretherketone semi-finished product mixture. The reaction is completed. Pour the mixture into an iron plate while hot, crush it after cooling, wash it with appropriate amount of ethanol 5 times, wash it with distilled water 5 times, and dry it at 150℃ for 6 hours to obtain polyetheretherketone. Test the weight average molecular weight, melt index and shear viscosity of the obtained sample.

[0107] The weight average molecular weight, melt index and shear viscosity of the polyetheretherketone prepared in the above examples are summarized in Table 1 below.

[0108] Table 1: Weight average molecular weight, melt index and shear viscosity of polyetheretherketone

[0109]

[0110]

[0111] The test results show that the polyetheretherketone prepared in the present invention has a significantly lower shear viscosity at a specific melt index and is particularly suitable for applications such as extruded sheets and rods and prepregs.

[0112] Some exemplary implementations are described below:

[0113] Embodiment 1. A polyetheretherketone, wherein the polyetheretherketone satisfies the following properties:

[0114] i) The polyetheretherketone has a repeating unit represented by the following formula (I):

[0115]

[0116] ii) the polyetheretherketone has a weight average molecular weight in the range of 15,000 to 45,000, as determined by GPC; and

[0117] iii) A nitrobenzoyloxy group is connected to the molecular chain end of the polyetheretherketone.

[0118] Embodiment 2. The polyetheretherketone as described in embodiment 1, wherein the nitrobenzoyloxy group is selected from one or more of 2-nitrobenzoyloxy, 3-nitrobenzoyloxy, and 4-nitro-benzoyl.

[0119] Embodiment 3. The polyetheretherketone as described in embodiment 1, wherein the nitrobenzoyloxy group is derived from a compound containing a nitrobenzoyloxy group, and the compound containing a nitrobenzoyloxy group is selected from one or more of 2-nitrobenzoic acid, 3-nitrobenzoic acid, 4-nitro-benzoic acid, 2-nitrobenzoyl fluoride, 3-nitrobenzoyl fluoride, and 4-nitro-benzoyl fluoride.

[0120] Embodiment 4. The polyetheretherketone as described in embodiment 1, wherein the polyetheretherketone contains 0.7 wt%-2.2 wt%, preferably 0.7 wt% to 0.8 wt% of the nitrobenzoyloxy group, and the weight percentage of the nitrobenzoyloxy group is the weight percentage of the nitrobenzoyloxy segment in the formed polyetheretherketone molecule.

[0121] Embodiment 5. The polyetheretherketone according to embodiment 1, wherein the polyetheretherketone has a structural formula represented by any one of the following formulas (II-1) to (II-3):

[0122]

[0123] Here, n is a positive integer in the range of 50 to 200.

[0124] Embodiment 6. The polyetheretherketone according to any one of embodiments 1 to 5, wherein when the polyetheretherketone has a melt index of 10 g / min-12 g / 10 min at 380 ° C, it is -1 The shear viscosity at s is not more than 450 Pa·s, preferably not more than 430 Pa·s, more preferably not more than 405 Pa·s, the melt index is measured according to GB / T-3682, and the shear viscosity is measured according to GB / T 25278-2010.

[0125] Embodiment 7. The polyetheretherketone of any one of embodiments 1 to 5, wherein the polyetheretherketone has a shear viscosity reduction of at least 10%, preferably at least 12%, more preferably at least 17%, compared to a polyetheretherketone having substantially the same melt index but not capped with nitrobenzoyloxy groups, the shear viscosity being at 400°C, 1000°C, or 1000°C. -1 The S value is determined according to GB / T 25278-2010.

[0126] Embodiment 8. A method for preparing the polyetheretherketone described in any one of embodiments 1-7, comprising the steps of:

[0127] i) Under an inert atmosphere, in the presence of an alkali metal carbonate, 4,4'-difluorobenzophenone and hydroquinone undergo nucleophilic polycondensation, and then

[0128] ii) during the nucleophilic polycondensation, adding a compound containing a nitrobenzoyloxy group to the reaction system of the nucleophilic polycondensation to continue the reaction; and then

[0129] iii) After the reaction is completed, cooling and purification are performed to obtain the polyetheretherketone.

[0130] Embodiment 9. The method of embodiment 8, wherein

[0131] The alkali metal carbonate includes sodium carbonate or a mixture of sodium carbonate and potassium carbonate, preferably includes a mixture of sodium carbonate and potassium carbonate, and the molar ratio of the two is in the range of 8.5-9.5:1;

[0132] The molar ratio of the alkali metal carbonate to the hydroquinone is in the range of 1.001-1.15:1;

[0133] The molar ratio of the 4,4'-difluorobenzophenone to the hydroquinone is in the range of 1.001-1.04:1;

[0134] The molar ratio of the compound containing a nitrobenzoyloxy group to the 4,4'-difluorobenzophenone is in the range of 0.095-0.105:1.

[0135] Embodiment 10. The method according to embodiment 8 or 9, wherein, during the nucleophilic polycondensation, the temperature is first raised to 220°C and maintained for 60-70 minutes; the temperature is then raised to 280°C; and after the nitrobenzoyloxy-containing compound is added, the temperature is further raised to 320°C and maintained for 50-60 minutes.

[0136] Embodiment 11. The method according to any one of embodiments 8 to 10, wherein during the nucleophilic polycondensation, an aromatic sulfone is used as a solvent, and the aromatic sulfone is selected from one or more of diphenyl sulfone, dibenzothiophene dioxide, thiophene dioxide and 4-phenylsulfonylbiphenyl, and preferably, the weight of the solvent is 3 times or more, but not more than 10 times, the weight of 4,4'-difluorobenzophenone.

[0137] Embodiment 12. A plate formed by extruding the polyetheretherketone described in any one of Embodiments 1 to 7 or the polyetheretherketone prepared by the method described in any one of Embodiments 8 to 11.

[0138] Embodiment 13. A rod formed by extruding the polyetheretherketone described in any one of Embodiments 1 to 7 or the polyetheretherketone prepared by the method described in any one of Embodiments 8 to 11.

[0139] Embodiment 14. A prepreg prepared from the polyetheretherketone described in any one of embodiments 1 to 7 or the polyetheretherketone prepared by the method described in any one of embodiments 8 to 11.

[0140] Although the present application is described with reference to a number of implementation methods and examples, a person skilled in the art will recognize that other implementation methods can be designed based on the content disclosed in the present application, which does not deviate from the scope of protection of the present application.

Claims

1. A polyetheretherketone, wherein the polyetheretherketone satisfies the following properties: i) The polyetheretherketone has a repeating unit represented by the following formula (I): ii) the polyetheretherketone has a weight average molecular weight in the range of 15,000 to 45,000, as determined by GPC; and iii) A nitrobenzoyloxy group is connected to the molecular chain end of the polyetheretherketone.

2. The polyetheretherketone according to claim 1, wherein The nitrobenzoyloxy group is selected from one or more of 2-nitrobenzoyloxy, 3-nitrobenzoyloxy, and 4-nitro-benzoyl.

3. The polyetheretherketone according to claim 1, wherein The nitrobenzoyloxy group is derived from a compound containing a nitrobenzoyloxy group, and the compound containing a nitrobenzoyloxy group is selected from one or more of 2-nitrobenzoic acid, 3-nitrobenzoic acid, 4-nitro-benzoic acid, 2-nitrobenzoyl fluoride, 3-nitrobenzoyl fluoride, and 4-nitro-benzoyl fluoride.

4. The polyetheretherketone according to claim 1, wherein The polyetheretherketone contains 0.7 wt% to 2.2 wt% of the nitrobenzoyloxy group, where the weight percentage of the nitrobenzoyloxy group is the weight percentage of the nitrobenzoyloxy segment in the formed polyetheretherketone molecule.

5. The polyetheretherketone according to claim 1, wherein The polyetheretherketone contains 0.7 wt% to 0.8 wt% of the nitrobenzoyloxy group, where the weight percentage of the nitrobenzoyloxy group refers to the weight percentage of the nitrobenzoyloxy segment in the formed polyetheretherketone molecule.

6. The polyetheretherketone according to claim 1, wherein The polyetheretherketone has a structural formula shown in any one of the following formulas (II-1) to (II-3): Here, n is a positive integer in the range of 50 to 200.

7. The polyetheretherketone according to any one of claims 1 to 6, wherein When the polyetheretherketone has a melt index of 10 g / min-12 g / 10 min at 380°C, it -1 The shear viscosity at 500 Pa·s is not more than 450 Pa·s, the melt index is measured according to GB / T-3682, and the shear viscosity is measured according to GB / T 25278-2010.

8. The polyetheretherketone according to any one of claims 1 to 6, wherein When the polyetheretherketone has a melt index of 10 g / min-12 g / 10 min at 380°C, it -1 The shear viscosity at 500 Pa·s is not more than 430 Pa·s, the melt index is measured according to GB / T-3682, and the shear viscosity is measured according to GB / T 25278-2010.

9. The polyetheretherketone according to any one of claims 1 to 6, wherein When the polyetheretherketone has a melt index of 10 g / min-12 g / 10 min at 380°C, it -1 The shear viscosity at 500 Pa·s is not more than 405 Pa·s, the melt index is measured according to GB / T-3682, and the shear viscosity is measured according to GB / T 25278-2010.

10. A method for preparing the polyetheretherketone according to any one of claims 1 to 9, comprising the steps of: i) Under an inert atmosphere, in the presence of an alkali metal carbonate, 4,4'-difluorobenzophenone and hydroquinone undergo nucleophilic polycondensation, and then ii) during the nucleophilic polycondensation, adding a compound containing a nitrobenzoyloxy group to the reaction system of the nucleophilic polycondensation to continue the reaction; and then iii) After the reaction is completed, cooling and purification are performed to obtain the polyetheretherketone.

11. A plate formed by extruding the polyetheretherketone according to any one of claims 1 to 9 or the polyetheretherketone prepared by the method according to claim 10.

12. A rod formed by extruding the polyetheretherketone according to any one of claims 1 to 9 or the polyetheretherketone prepared by the method according to claim 10.

13. A prepreg prepared from the polyetheretherketone according to any one of claims 1 to 9 or the polyetheretherketone prepared by the method according to claim 10.

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