Method for producing polyetherketoneketone

Abstract

The invention relates to a method for producing a polyetherketoneketone which comprises bringing an aromatic ether which is diphenyl ether, 1,3-bis(4-phenoxybenzoyl)benzene, 1,4-bis (4-phenoxybenzoyl) benzene or a mixture thereof into contact with an acyl chloride which is isophthaloyl chloride, terephthaloyl chloride or a mixture thereof, a Lewis acid, and a first fraction s1 of a reaction solvent, so as to form a premix at a temperature T0 of less than or equal to 25°C, and bringing the premix formed at T0 into contact with a fraction s2 of the reaction solvent, the fraction s2 of reaction solvent being preheated, so as to form a reaction mixture brought to a temperature T1.

Description

[0001] Description Title: Process for manufacturing polyetherketoneketone Technical field The invention relates to the field of polyetherketoneketones. More particularly, the invention relates to a process for manufacturing polyetherketoneketone by precipitating polymerization, carried out electrophilically. The invention also relates to the polymer, in particular in the form of a powder of porous scales, capable of being obtained by this process. Prior art There is known, in particular from US 3,791,890, a process for the electrophilic manufacture of polyetherketoneketone from a mixture of isophthaloyl chloride and terephthaloyl chloride (acyl chlorides), reacted with diphenyl ether (aromatic ether), in the presence of aluminum chloride (Lewis acid), and using ortho-dichlorobenzene as reaction solvent.Example 3 of US 3,791,890 describes the preparation of a premix comprising acyl chlorides, diphenyl ether and aluminum chloride in a first fraction of ortho-dichlorobenzene at a temperature of about -5°C. The reaction is then initiated by dispersing this premix in a second fraction of ortho-dichlorobenzene preheated to 100°C. This sequence of first preparing a cold premix and then dispersing the premix in preheated reaction solvent allows for an extremely rapid temperature rise of the reaction mixture. Although the mechanisms occurring in the reaction medium are not fully understood, US 3,791,890 indicates that this would separate the polymer particles being formed, facilitate the polymerization reaction, and prevent the coagulation of the particles into a gelatinous mass characteristic of this polymerization reaction.As shown in part experimentally, the polymers obtained by a process according to this prior art where a premix is ​​dispersed in reaction solvent at a temperature characterized in the present invention as high, preferably at least about 100°C, have several disadvantages. Firstly, a chromatographic analysis of such polymers of the prior art revealed that they comprise a significant amount of low molecular weight oligomers, in particular oligomers having a weight of 500 g / mol to 3000 g / mol. However, these low molecular weight oligomers can negatively impact the processing and / or certain thermal characteristics of the polymer. For example, the presence of low molecular weight oligomers can be the cause of defects, in particular black spots, on objects obtained by extrusion. In addition, deposits of degraded material can form in the dies used for extrusion.Furthermore, these low molecular weight oligomers, especially those with a weight of 500 g / mol to 3000 g / mol, are difficult to extract even by advanced extraction methods. Secondly, such polymers are in the form of large particles with a rather heterogeneous size distribution, which is detrimental for many applications where the powder must be able to flow easily and the particles must have a homogeneous behavior. Also known from WO 9523821 is an alternative method for avoiding the formation of a gelatinous mass during polymerization. According to this method, a dispersant of the polymer makes it possible to avoid the coagulation of a sticky polymer product formed during polymerization.This document explains that the sticky polymer product is actually due to the complex formed by a low molecular weight polymer with the Lewis acid at the beginning of the polymerization reaction and which precipitates in the form of a gel that covers the walls of the reactor and the stirrer. Among the dispersants, the patent document designates for example compounds having as a pendant group a moiety of formula: [Chem 1]. . It is also known, in particular from US20120263953, the use of control agents acting as dispersants, and in particular the use of benzoic acid and its derivatives. The addition of a dispersant nevertheless has several disadvantages. The use of certain dispersants, in particular those having a moiety of formula (0) as illustrated above, leads to overconsumption of the Lewis acid in the process, the latter also forming a complex with the dispersant. In addition, this complicates the management of process effluents, and in particular the exploitation / recycling of the effluent containing the Lewis acid. Finally, the dispersant cannot be completely eliminated from the manufactured polymer and can have a detrimental effect on the thermal stability of the polymer.Thus, there is currently a need to improve the processes for manufacturing polyetherketoneketone according to the prior art in order to reduce the quantity of low molecular weight molecules in the polymer and / or in order to obtain a powder having a more homogeneous distribution, while continuing to limit the coagulation of the polymer particles into a gelatinous mass characteristic of the electrophilic polymerization reaction of polyetherketoneketone. Objectives of the invention An objective of the invention is to provide a simple process for manufacturing polyetherketoneketone making it possible to limit fouling of the polymerization reactor. Another objective is, at least according to certain embodiments, to provide a process having a good polymer manufacturing yield.Another objective of the invention is, at least according to certain embodiments, to provide a method for manufacturing a polymer having fewer low molecular weight molecules / oligomers, in particular fewer molecules / oligomers having a molecular weight of less than 3000 g / mol, and more particularly fewer molecules / oligomers having a molecular weight ranging from 500 g / mol to 3000 g / mol, compared to the aforementioned polymers of the prior art. Another objective of the invention is, at least according to certain embodiments, to provide a method for obtaining polymer particles having a sufficiently homogeneous size distribution. Another objective of the invention is, at least according to certain embodiments, to provide a method for obtaining polymer particles of a sufficiently small size.Another objective of the invention is, at least according to certain embodiments, to propose a method for obtaining polymer particles not comprising, or even in trace form, a dispersing agent. Another objective of the invention is to propose a polymer, in particular in powder form, which is easier to handle and / or makes it possible to obtain parts having fewer defects, in particular for objects obtained by extrusion processes. Summary of the invention The invention relates to a method for manufacturing a polyetherketoneketone.This process comprises: - bringing into contact an aromatic ether being diphenyl ether, 1,3-bis(4-phenoxybenzoyl)benzene, 1,4-bis(4-phenoxybenzoyl)benzene or a mixture thereof, an acyl chloride being isophthaloyl chloride, terephthaloyl chloride, or a mixture thereof, a Lewis acid, and a first fraction s1 of a reaction solvent, so as to form a premixture at a temperature T0 less than or equal to 25°C; - bringing the premixture formed at T0 into contact with a fraction s2 of the reaction solvent, the fraction s2 of reaction solvent being preheated, so as to form a reaction mixture brought to a temperature T1 ranging from 40°C to 80°C. Optionally, the method comprises maintaining the formed premixture at T0 before forming the reaction mixture brought to T1. Optionally, the method comprises maintaining the formed reaction mixture at T1.According to some embodiments, the reaction solvent is selected from the group consisting of: ortho-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2,3-trichlorobenzene, ortho-difluorobenzene, and mixtures thereof. Preferably, the reaction solvent is ortho-dichlorobenzene. According to some embodiments, the Lewis acid is selected from the group consisting of: aluminum trichloride, aluminum tribromide, antimony pentachloride, antimony pentafluoride, indium trichloride, gallium trichloride, boron trichloride, boron trifluoride, zinc chloride, ferric chloride, stannic chloride, titanium tetrachloride, molybdenum pentachloride, and mixtures thereof. Preferably, the Lewis acid is aluminum trichloride. Preferably, the aromatic ether consists essentially of, or consists of, 1,4-bis(4-phenoxybenzoyl)benzene. According to certain embodiments s2≥ 0.25. .According to some embodiments s1≥ 0.25. According to some embodiments, s1≥ 0.25 and s2≥ 0.25. According to some embodiments, s1+ s2≥ 0.75. According to some embodiments, s1+ s2= 1. According to some embodiments, T1 ranges from 40°C to 52°C, or T1 ranges from 52°C to 60°C, or T1 ranges from 60°C to 68°C, or T1 ranges from 68°C to 80°C. According to certain embodiments, the reaction mixture is brought, and optionally maintained, at T1 until the reaction mixture formed has a fraction of molecular masses strictly less than 500g / mol in PMMA equivalent which is less than or equal to 50%, preferably less than or equal to 25%, and even more preferably less than or equal to 15%.According to certain embodiments, the reaction medium is brought to and optionally maintained at a temperature T2 ranging from a temperature at least 10°C higher than T1 to a temperature of 120°C, after the step of forming and optionally maintaining the reaction mixture at temperature T1. According to certain embodiments, the method comprises a step of purifying the mixture of products obtained at the end of polymerization. According to certain embodiments, a chain-limiting agent is added before the step of forming the reaction mixture brought to a temperature T1. According to certain embodiments, the molar ratio of aromatic ether(s) relative to the reaction solvent having been introduced in total into the reaction mixture is: 0.005 to 0.030, preferably: 0.008 to 0.025, and extremely preferably: 0.010 to 0.022.According to certain embodiments, the premix formed at T0 is dispersed in all or part of the fraction s2 of the preheated reaction solvent to form the reaction mixture brought to T1. According to certain embodiments, the step of bringing the premix into contact with the fraction s2 of the preheated reaction solvent to form the reaction mixture brought to T1 is carried out with stirring, and preferably using a double-flow stirring means. According to certain embodiments, the polyetherketoneketone obtained by the process consists of repeating units of formula (I) and formula (II), the proportion of units of formula (II) relative to the units of formula (I) being from 55:45 to 95:5, the unit of formula (I) having the chemical formula: [Chem 2]. and the unit of formula (II) having the chemical formula: [Chem 3] (II). The invention also relates to a polyetherketoneketone, in particular in powder form, derived therefrom. This polyetherketoneketone is advantageously obtained by the electrophilic process according to the invention. The polyetherketoneketone consists of three fractions A, B and C of molecular masses, in which A represents the fraction in percent of the molecular masses strictly less than 500 g / mol in PMMA equivalent, B represents the fraction in percent of the molecular masses ranging from 500 g / mol to 3000 g / mol in PMMA equivalent, and C represents the fraction in percent of the molecular masses strictly greater than 3000 g / mol in PMMA equivalent. It is characterized in that: A+B ≤ 5.0% and A + B + C = 100%. According to certain embodiments B ≤ 4.0%, preferably B ≤ 3.5%, and more preferably B ≤ 3.3%.In some embodiments, the polyetherketoneketone has an inherent viscosity of greater than or equal to 0.4 dl / g, preferably greater than or equal to 0.5 dl / g, preferably greater than or equal to 0.6 dl / g, and more preferably greater than or equal to 0.7 dl / g. In some embodiments, the polyetherketoneketone has an inherent viscosity of less than or equal to 2 dl / g, and preferably less than or equal to 1.5 dl / g. In some embodiments, the polyetherketoneketone consists of repeating units of formula (I) and formula (II), the proportion of units of formula (II) to units of formula (I) being from 55:45 to 95:5. In some embodiments, the polyetherketoneketone does not comprise a dispersing agent.According to certain embodiments, the polyetherketoneketone powder has a mass proportion of particles of size strictly greater than 1000 micrometers less than or equal to 50%, as obtained by sieving using a sieve with a mesh size equal to 1 millimeter. According to certain embodiments, the powder has a mass proportion of particles of size strictly greater than 1000 micrometers less than or equal to 10%, and preferably less than or equal to 5%. According to a first variant, the mass proportion of particles of size ranging from 315 micrometers to 1000 micrometers is greater than or equal to 50%, and preferably greater than or equal to 80%. According to this first variant, the powder preferably has a mass proportion of particles of size strictly less than 315 micrometers less than or equal to 10%.According to a second variant, the mass proportion of particles with a size strictly less than 630 micrometers is greater than or equal to 50%, preferably greater than or equal to 70%, and more preferably greater than or equal to 85%. According to certain embodiments, the powder has a packed density greater than or equal to 180 kg / m. 3 and less than or equal to 400 kg / m 3. Figures [Figure 1] represents the mass proportions (ordinates, expressed in percent) for different ranges of particle sizes (abscissas, expressed in millimeters, measured using sieves, for tests #1 (55°C), #2 (65°C) and #3 (90°C; comparative) according to Example 1. [Figure 2] represents the fraction A (ordinates, expressed in %) of the molecular masses strictly lower than 500 g / mol for the mixtures of products obtained according to Example 2 at different polymerization holding times at 65°C (abscissas, expressed in minutes) after formation of the reaction mixture at 65°C. Detailed description of the invention The polyetherketoneketones, also called PEKK, prepared according to the process of the invention are essentially constituted, preferentially constituted, of: [Chem 4] (I), also designated under the name of isophthalic unit or by the initial “I”; [Chem 5] (II), also referred to as the terephthalic unit or by the initial "T"; and, their mixture. According to certain embodiments, the polyetherketoneketones manufactured according to the invention are essentially constituted, that is to say comprise at least 95% by moles, preferably at least 98% by moles, of the repeating units of formula (I) and / or of formula (II), considered where appropriate as a whole, relative to the total number of moles of the repeating units of the polymer. According to certain embodiments, the polyetherketoneketones manufactured according to the invention are essentially constituted, or constituted, of repeating units of formula (II) and optionally of repeating units of formula (I), the proportion of units of formula (II) relative to the units of formula (I), noted ratio T:I being from 50:50 to 100:0.In particular, the T:I ratio may be from 50:50 to 55:45, or from 55:45 to 65:35, or from 65:35 to 75:25, or from 75:25 to 85:15, or from 85:15 to 95:5, 95:5 to 100:0. According to certain embodiments, the polyetherketoneketones consist of repeating units of formula (I) and of formula (II), the proportion of units of formula (II) relative to the units of formula (I), noted T:I ratio, being from 55:45 to 95:5. According to certain embodiments, the polyetherketoneketones according to the invention are essentially constituted, or constituted, of repeating unit (I) and optionally of repeating unit of formula (II), with a T:I ratio of 0:100 to 50:50. In particular, the T:I ratio can be from 0:100 to 5:95, or from 5:95 to 10:90, or from 10:90 to 20:80, or from 20:80 to 30:70, or from 30:70 to 40:60, or from 40:60 to 50:50.The polymerization reaction involved is a polycondensation reaction involving an electrophilic substitution between one or more aromatic ethers with one or more acyl chlorides, in the presence of a Lewis acid and optionally a chain-limiting agent in a reaction solvent. The polymerization reaction is furthermore precipitating because the polymer formed precipitates in the reaction medium. It is also exothermic. Hydrogen chloride is produced during the polycondensation. The invention consists in preparing a premixture comprising the aromatic ether(s), the acyl chloride(s) and the Lewis acid at a sufficiently low temperature so that the polymerization reaction remains extremely limited or is even inhibited in the premixture.The polymerization reaction is then activated by dispersing the premix with all or part of the preheated reaction solvent so that the reaction mixture immediately or almost immediately reaches a moderate polymerization temperature of 40°C to 80°C. The inventors have remarked, quite surprisingly, that carrying out the start of the polymerization reaction under these moderate temperature conditions made it possible i) to obtain a polymer having a lower proportion of low molecular weight molecules than for the processes of the prior art where the polymerization reaction is carried out by contacting the premix with a reaction solvent preheated to 100°C, ii) while ensuring limited fouling by gel formation in the polymerization reactor, and iii) to obtain polymer particles of smaller sizes and having a more homogeneous size distribution.The lower proportion of low molecular weight molecules is a completely counterintuitive result for a precipitating polymerization being carried out at least in part at lower temperature (40°C to 80°C instead of 100°C). Indeed, the skilled person would have expected that the species present in the reaction medium would be less soluble at lower temperature and that the probability of reaction between the reactive species would be lower, thus generating a polymer with a higher proportion of low molecular weight molecules. The acyl chloride is chosen from the group consisting of: terephthaloyl chloride, isophthaloyl chloride, and their mixture. A number of measures can be taken to ensure that the acyl chloride(s) used have a satisfactory degree of purity.Indeed, acyl chlorides are easily hydrolyzable species and may in particular contain as impurities a certain quantity of hydrolyzed species if they are not stored and / or handled under appropriate conditions. In particular, the acyl chlorides must not be brought into contact at any time with water and / or a humid atmosphere before being introduced into the reactor. It may thus be advantageous to store the acyl chlorides in a sealed container without contact with the ambient air, or alternatively in a container containing dry air. Advantageously, the acyl chlorides may be kept under a dry nitrogen atmosphere before being introduced into the reactor in order to avoid any contact with the ambient air. The aromatic ether is chosen from the group consisting of: diphenyl ether, 1,3-bis(4-phenoxybenzoyl)benzene, 1,4-bis(4-phenoxybenzoyl)benzene or their mixture.1,3-bis(4-phenoxybenzoyl)benzene has the chemical formula: [Chem 6]. 1,4-bis(4-phenoxybenzoyl)benzene has the chemical formula: [Chem 7] In some embodiments, the aromatic ether or mixture of aromatic ethers comprises at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 95%, or at least 99% by mole of 1,3-bis(4-phenoxybenzoyl)benzene and / or 1,4-bis(4-phenoxybenzoyl)benzene, if applicable taken together, relative to the total number of moles of aromatic ether(s). In some embodiments, a mixture of aromatic ethers is used. It consists essentially of, or consists of, 1,3-bis(4-phenoxybenzoyl)benzene and 1,4-bis(4-phenoxybenzoyl)benzene. In some embodiments, a mixture of aromatic ethers is used. It consists of 1,4-bis(4-phenoxybenzoyl)benzene and diphenyl ether.The mixture may comprise up to 20 mol%, preferably up to 10 mol%, more preferably up to 5 mol%, and extremely preferably up to 1 mol% of diphenyl ether, based on the total number of moles of aromatic ethers. In some embodiments, the aromatic ether consists essentially of, or consists of, 1,4-bis(4-phenoxybenzoyl)benzene. In some embodiments, a mixture of aromatic ethers is used. It consists of 1,3-bis(4-phenoxybenzoyl)benzene and diphenyl ether. The mixture may comprise up to 20 mol%, preferably up to 10 mol%, more preferably up to 5 mol%, and extremely preferably up to 1 mol% of diphenyl ether, based on the total number of moles of aromatic ethers. In some embodiments, the aromatic ether consists essentially of, or consists of, 1,3-bis(4-phenoxybenzoyl)benzene.In some embodiments, the aromatic ether consists essentially of, or consists of, 1,4-bis(4-phenoxybenzoyl)benzene. A polyetherketoneketone having a T:I ratio of 50:50 to 100:0 can be obtained by mixing isophthaloyl and terephthaloyl chlorides and adjusting the isophthaloyl chloride / terephthaloyl chloride ratio. In some embodiments, the acyl chloride is solely terephthaloyl chloride. A polyetherketoneketone having a T:I ratio of 50:50 to 100:0 can be obtained by a mixture consisting essentially of, or consisting of, 1,3-bis(4-phenoxybenzoyl)benzene and 1,4-bis(4-phenoxybenzoyl)benzene and adjusting the ratio 1,3-bis(4-phenoxybenzoyl)benzene / 1,4-bis(4-phenoxybenzoyl)benzene.Similarly, in some embodiments, the aromatic ether consists essentially of, or consists of, 1,3-bis(4-phenoxybenzoyl)benzene (respectively the acyl chloride is only isophthaloyl chloride). A polyetherketoneketone having a T:I ratio of 0:100 to 50:50 can be obtained by adjusting the ratio of isophthaloyl chloride / terephthaloyl chloride (respectively by adjusting the ratio of 1,3-bis(4-phenoxybenzoyl)benzene / 1,4-bis(4-phenoxybenzoyl)benzene). The Lewis acid may be selected from the group consisting of: aluminum trichloride, aluminum tribromide, antimony pentachloride, antimony pentafluoride, indium trichloride, gallium trichloride, boron trichloride, boron trifluoride, zinc chloride, ferric chloride, stannic chloride, titanium tetrachloride, molybdenum pentachloride, and mixtures thereof. Preferably, only one type of Lewis acid is used in the polymerization reaction.Among the Lewis acids cited above, aluminum trichloride, boron trichloride, aluminum tribromide, titanium tetrachloride, antimony pentachloride, ferric chloride, gallium trichloride and molybdenum pentachloride are preferred. Aluminum trichloride is particularly preferred. Preferably, the Lewis acid is added in solid form. Alternatively, it may also be added in suspension or colloid form, i.e., as a heterogeneous mixture of solid Lewis acid particles in a solvent, or in solution form, i.e., as a homogeneous mixture in a solvent. The solvent of the suspension / colloid or solution is advantageously the reaction solvent. According to certain variants, the Lewis acid is added in particulate form, such as powder form (having, for example, a Dv80 of less than 1 mm and preferably a Dv50 of less than 0.5 mm).The parameters Dv80 and Dv50 are respectively the particle sizes at 80. ème and 50 èmepercentiles (by volume) of the cumulative particle size distribution of the Lewis acid particles. These parameters may in particular be determined by sieving. The Lewis acid used in the process according to the invention preferably has a degree of purity such that it comprises less than 0.1% by weight of insoluble matter, and more preferably less than 0.05% by weight of insoluble matter, as measured gravimetrically, when it is introduced with stirring into water at a concentration of 11% by weight at 20°C and substantially dissolved. The reaction solvent may be chosen from the group consisting of: ortho-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2,3-trichlorobenzene, ortho-difluorobenzene, and mixtures thereof. Ortho-dichlorobenzene is particularly preferred. The reaction solvent preferably contains less than 500 ppm by weight of water in order to limit the hydrolysis reaction of the acyl chloride or mixture of acyl chlorides.Advantageously, the reaction solvent contains less than 250 ppm by weight of water, preferably less than 150 ppm by weight of water, and more preferably less than 100 ppm by weight of water. In preferred embodiments, the aromatic ether or the mixture of aromatic ethers also preferably contains less than 500 ppm by weight of water in order to limit the hydrolysis reaction of the acyl chloride or the mixture of acyl chlorides. The same preferred value ranges as for the reaction solvent apply mutatis mutandis to the aromatic ether or the mixture of aromatic ethers. In still more preferred embodiments, the reaction solvent and the aromatic ether or the mixture of aromatic ethers comprise altogether less than 500 ppm by weight of water in order to limit the hydrolysis reaction of the acyl chloride or the mixture of acyl chlorides.The same preferred value ranges as for the reaction solvent apply mutatis mutandis to the reaction solvent and the aromatic ether or mixture of aromatic ethers, considered together. In order to ensure the absence of traces of water in a reactor, the process advantageously comprises a preliminary drying step, i.e. reduction of the water content, of the reaction solvent and / or the aromatic ether or mixture of aromatic ethers, before bringing them into contact with the acyl chloride or with the mixture of acyl chlorides. Means for carrying out this preliminary drying step include, for example, distillation of the chemical compounds, or bringing them into contact with a molecular sieve or bringing them into contact with a dehydrating agent such as a small amount of aluminum chloride. The use of one or more chain-limiting agents in the reaction medium is optional.Their addition allows better control of the degree of polymerization and therefore the viscosity of the polymer to be manufactured. It also allows better control of the chain ends of the polymer, and where appropriate, ensures better stability, in particular better thermal stability, of the polymer. Two types of chain limiting agents can be used: a nucleophilic chain limiting agent or an electrophilic chain limiting agent. According to certain embodiments, the chain limiting agent is a nucleophilic chain limiting agent. The nucleophilic chain limiting agent can in particular be chosen from the compounds of the following chemical formula: [Chem 8]. in which: X1 represents: a covalent bond, -O-, or -S-; and X2 represents, C6H5CO, or C6H5SO2; or of the following chemical formula: [Chem 9] in which: X3 is a halogen, an alkyl group or an alkoxy group having 1 to 10 carbon atoms. Preferably, the nucleophilic chain-limiting agent is chosen from the group consisting of: 4-phenoxybenzophenone, 4-phenoxydiphenylsulfone, anisole, fluorobenzene, chlorobenzene, biphenyl, toluene, and a mixture thereof. A particularly advantageous nucleophilic chain-limiting agent is 4-phenoxybenzophenone. According to certain embodiments, the chain-limiting agent is an electrophilic chain-limiting agent. The electrophilic chain-limiting agent may in particular be chosen from the compounds of the following formula: [Chem 10] in which: X4 represents: a hydrogen atom, a halogen atom, an alkyl or alkoxy group having 1 to 10 carbon atoms, a nitro group, C6H5CO or C6H5SO2; or of the following formula: [Chem 12] [Chem 13] (IX), in which: X nrepresents n groups, n being an integer chosen between 2 and 5, each group being independently chosen from: a halogen atom, an alkyl or alkoxy group having 1 to 10 carbon atoms, a nitro group, C6H5CO or C6H5SO2. Preferably, the electrophilic chain limiting agent is chosen from the group consisting of: benzoyl chloride, acetyl chloride, 3,5-dichlorobenzoyl chloride, 3,5-difluorobenzoyl chloride, p-fluorobenzoyl chloride, p-chlorobenzoyl chloride, p-methoxybenzoyl chloride, benzene sulfonyl chloride, p-chlorobenzene sulfonyl chloride, p-methylbenzene sulfonyl chloride, 4-benzoylbenzoyl chloride, and a mixture thereof. Advantageously, the chain limiting agent is an electrophilic chain limiting agent, chosen from benzoyl chloride, p-fluorobenzoyl chloride, 3,5-difluorobenzoyl chloride, or a mixture thereof.These chain-limiting agents are easy to dose since they are in liquid form at room temperature, have a low cost and ensure good thermal stability for the polymer. According to certain embodiments, a chain-limiting agent being benzoyl chloride is used. According to certain embodiments, a chain-limiting agent being p-fluorobenzoyl chloride is used. According to certain embodiments, a chain-limiting agent being 3,5-difluorobenzoyl chloride is used. In the embodiments where a chain-limiting agent is used, the latter can be added at any stage of the process. According to certain embodiments, all or part of the chain-limiting agent can be added with the other chemical species to form the premix at T0 or during the stage of maintaining the premix at T0.Advantageously, the chain-limiting agent can be added to the reaction medium in its entirety, before the step of forming the reaction mixture brought to a temperature T1. The use of a dispersing agent in the reaction medium is optional and does not present any particular advantage. Indeed, the method according to the invention generally makes it possible to dispense with the use of such agents since it makes it possible to minimize fouling by bringing the reaction medium from T0 to T1 almost immediately. According to advantageous embodiments, no dispersing agent is added to the reaction medium. This has several advantages in particular: it avoids overconsumption of the Lewis acid introduced and / or facilitates the recovery of the process effluents, in particular the effluent containing the Lewis acid, and / or makes it possible to manufacture a polyetherketoneketone devoid of any trace of dispersing agent.The polymerization reaction being a polycondensation, the aromatic ether or the mixture of aromatic ethers is introduced into the reaction medium under substantially stoichiometric conditions relative to the acyl chloride or the mixture of acyl chlorides. The molar proportion of aromatic ether(s) relative to the acyl chloride(s) having been introduced in total into the reaction medium at the end of the contacting step to form the premix at T0 is preferably from 0.9:1.1 to 1.1:0.9. According to advantageous embodiments, the aromatic ether(s) is / are introduced in excess relative to the acyl chloride(s), preferably with a molar ratio of aromatic ether(s) relative to the acyl chloride(s) of 1.001 to 1.1.In these embodiments, if a chain-limiting agent is used, it is preferably an electrophilic chain-limiting agent, for example, and advantageously, benzoyl chloride or p-fluorobenzoyl chloride or 3,5-difluorobenzoyl chloride. The molar proportion of Lewis acid relative to the aromatic ether(s) having been introduced in total into the reaction medium at the end of the contacting step to form the premix at T0 is preferably such that the Lewis acid is in slight excess relative to all the ether functions, and where appropriate ketone, of the aromatic ether or of the mixture of aromatic ethers and of the acyl chloride functions of isophthaloyl chloride, terephthaloyl chloride, or their mixture.The molar proportion of Lewis acid relative to the aromatic ether(s) having been introduced in total into the reaction medium at the end of the contacting step to form the premix at T0 is preferably from 5.0 to 7.0, and very preferably from 5.1 to 6.5, in the embodiments where the aromatic ether is essentially constituted, or constituted of 1,3-bis(4-phenoxybenzoyl)benzene, 1,4-bis(4-phenoxybenzoyl)benzene, or a mixture thereof. The molar proportion of aromatic ether(s) relative to the reaction solvent(s) having been introduced in total into the reaction medium at the end of the polymerization is preferably at least equal to 0.005, very preferably greater than or equal to 0.008, and more preferably greater than or equal to 0.010.The molar proportion of aromatic ether(s) relative to the reaction solvent(s) having been introduced in total into the reaction medium at the end of the polymerization is greater than or equal to 0.010, or greater than or equal to 0.011, or greater than or equal to 0.012, or greater than or equal to 0.013, or greater than or equal to 0.014, or greater than or equal to 0.015, or greater than or equal to 0.016, or greater than or equal to 0.17. Conversely, given that the less reaction solvent the reaction medium contains, the more likely it will be to form fouling during the polymerization, especially in the absence of a dispersing agent, the molar ratio of aromatic ether(s) relative to the reaction solvent(s) having been introduced in total into the reaction medium at the end of the polymerization is preferably less than or equal to 0.030, very preferably less than or equal to 0.025 and extremely preferably less than or equal to 0.022.Thus, according to certain embodiments, the molar ratio of aromatic ether(s) relative to the reaction solvent(s) introduced in total into the reaction medium is from 0.005 to 0.030, preferably from 0.008 to 0.025, and extremely preferably from 0.010 to 0.022. The molar ratio of aromatic ether(s) to the reaction solvent(s) introduced in total into the reaction medium may in particular be from 0.011 to 0.022, from 0.012 to 0.022, from 0.013 to 0.022, from 0.014 to 0.022, from 0.015 to 0.022, from 0.016 to 0.022, or from 0.017 to 0.022. The molar proportion of chain-limiting agent(s) to the aromatic ether(s) having been introduced in total into the reaction medium may be from 0 to 0.12. The process according to the invention initially comprises bringing the chemical compounds involved in the polymerization reaction into contact.This step notably comprises bringing the reactants into contact: aromatic ether(s), acyl chloride(s), and Lewis acid in a fraction s1 of the reaction solvent, and optionally with all or part of a chain-limiting agent. These different compounds can in theory be mixed with each other in any order whatsoever. For the purposes of the invention, we speak of “premixing” from the moment when all or part of the aromatic ether(s), all or part of the acyl chloride(s) and all or part of the Lewis acid have been brought into contact in all or part of the fraction s1 of the reaction solvent at a temperature T0 less than or equal to 25°C. In other words, the “premixing” begins to exist at the moment when a polymerization could be initiated thermodynamically. The polymerization is, however, inhibited or at the very least remains extremely limited kinetically at T0. According to certain embodiments, T0 is advantageously less than or equal to 15°C.It is more preferably less than or equal to 10°C. It may, according to certain embodiments, be less than or equal to 8°C, or less than or equal to 5°C, or less than or equal to 0°C, or even less than or equal to -5°C. According to certain embodiments, T0 may in particular be in the temperature range from -10°C to 15°C, and preferably from -5°C to 10°C. The fraction s1 of reaction solvent is calculated relative to the total reaction solvent used to carry out the polymerization reaction. It corresponds to the fraction of solvent used during contacting at T0 relative to the total quantity of reaction solvent used at the end of the polymerization.Indeed, in the process according to the invention, the reaction solvent is added at different stages as described below: in addition to using a fraction s1 of reaction solvent to form the premix at T0, a fraction s2 of preheated reaction solvent is used to form the reaction mixture at T1, and a fraction s3 of reaction solvent can optionally be used for an optional stage where the reaction medium is brought to and maintained at a temperature T2. We have: s1 + s2 + s3 = 1. The fraction s1 of the reaction solvent can be from 0.25 to 0.75. The fraction of the solvent s1 can be from 0.25 to 0.35, or from 0.35 to 0.45, or from 0.45 to 0.55, or from 0.55 to 0.65, or from 0.65 to 0.75. The solvent fraction s1 will be advantageously chosen by the person skilled in the art according to the available conditions for implementing the process.A sufficiently high value of s1 allows in particular contact of the Lewis acid with the aromatic ether(s) and / or the acid chloride(s) sufficiently rapid while maintaining the reaction medium at T0. A sufficiently high value of s1 also makes it easier to transfer, if necessary, the premix at T0 to another reactor by gravity and / or pumping means. A sufficiently low value of s1 allows in particular contact of the premix at T0 with the fraction s2 of preheated solvent sufficiently rapid while facilitating maintenance of the reaction medium at T1. The contacting step to obtain the premixture ends, or in other words the premixture is formed, when all of the aromatic ether or mixture of aromatic ethers, the acyl chloride or mixture of acyl chlorides, the Lewis acid, and the fraction s1 of the reaction solvent have been contacted.The premix formed may be maintained at T0 for a certain period of time, for example to ensure good homogenization of the reaction medium. Preferably, the contacting step to obtain the premix is ​​carried out with stirring. For the purposes of the invention, when it is indicated that the contacting of the reactants to prepare the premix is ​​carried out at T0 and / or that the premix formed is maintained at T0, this does not presuppose that the temperature remains fixed, but means that the temperature of the reaction medium remains within the temperature range imposed for T0. The contacting step to form the premix at T0 generally lasts from 15 minutes to 12 hours. On an industrial scale, this step is preferably from 25 minutes to 6 hours, and more preferably from 30 minutes to 4 hours.Once the premix is ​​formed, the reaction medium may optionally be maintained at T0 for less than one hour, and preferably for 30 minutes or less. Once the premix is ​​formed at T0, the reaction medium may optionally be maintained at T0 for 15 minutes or less, or for 10 minutes or less, or for 5 minutes or less. Preferably, the maintenance at T0 of the formed premix is ​​carried out with stirring. According to certain embodiments, the reaction medium is maintained at T0 during the contacting step and during the optional step of maintaining the formed premix for 15 minutes to 13 hours, preferably for 25 minutes to 7 hours and more preferably for 30 minutes to 5 hours.According to advantageous embodiments, the aromatic ether(s), the acyl chloride(s), and the Lewis acid may be added in two separate phases to prepare the premixture in the presence of the fraction s1 of the reaction solvent. In a first phase, two of the reactants are mixed. In a second phase, the third reactant is added in its entirety to the previously obtained mixture, the reaction medium then being maintained at the temperature T0 between at the latest the start of the second phase where the third reactant begins to be added and the end of the second phase where the third reactant finishes being added. According to a first embodiment, said first phase comprises the preparation of a mixture comprising all of the aromatic ether or the mixture of aromatic ethers with all of the acyl chloride or the mixture of acyl chlorides, in the fraction s1 of the reaction solvent.The second phase comprises the addition of all of the Lewis acid to the mixture obtained in the first phase, the temperature of the reaction medium being maintained at T0. According to a second embodiment, said first phase comprises the preparation of a mixture comprising all of the acyl chloride or the mixture of acyl chlorides with all of the Lewis acid, in the fraction s1 of reaction solvent. The second phase comprises the addition of all of the aromatic ether or the mixture of aromatic ethers to the mixture obtained in the first phase, the temperature of the reaction medium being maintained at T0. The section below presents in detail these two particularly advantageous embodiments of implementing the step of bringing the chemical compounds into contact in a reactor. The method according to the invention is in no way limited to these embodiments given for illustrative purposes.Advantageously, the first embodiment is implemented according to the following sequence: First, the fraction s1 of the reaction solvent is introduced into the reactor. Second, the aromatic ether or the mixture of aromatic ethers is added and dispersed within the reaction solvent in the reactor with stirring. Third, in order to guarantee the absence of traces of water in the reactor, distillation is carried out as well as inerting the reactor headspace with nitrogen. Alternatively or in addition, a dehydrating agent, and in particular aluminum chloride in small quantities, can be added so as to eliminate the last traces of water. Fourth, the acyl chloride or the mixture of acyl chlorides is introduced into the reactor with stirring. Fifth, the Lewis acid is introduced with stirring.Since the complexation of the Lewis acid with the acyl chloride(s) is an exothermic reaction, the Lewis acid is added slowly enough to the reactor so that the premixture can be maintained at temperature T0. The Lewis acid addition step can last from 15 minutes to 12 hours. An optional homogenization step at T0 of the premixture formed can be observed, if necessary. This optional homogenization step can last 1 hour or less and preferably 30 minutes or less. The second advantageous embodiment can be implemented according to the following sequence: First, the fraction s1 of the reaction solvent is introduced into the reactor. Second, in order to guarantee the absence of traces of water in the reactor, distillation is implemented as well as inerting the reactor headspace with nitrogen.Alternatively or additionally, a dehydrating agent, and in particular a small amount of aluminum chloride, can be added to remove the last traces of water. Third, the acyl chloride or the mixture of acyl chlorides is introduced into the reactor with stirring. Fourth, the Lewis acid is introduced with stirring. Since the complexation of the Lewis acid with the acyl chloride(s) is an exothermic reaction, the Lewis acid is added slowly enough to the reactor to maintain the reaction mixture at temperature T0. Fifth, once all of the Lewis acid has been completely introduced, the aromatic ether or the mixture of aromatic ethers is introduced to form the premixture. The step of adding the aromatic ether can last from 15 minutes to 12 hours. An optional step of homogenization at T0 of the premixture formed can be observed, if necessary.This optional homogenization step can last 1 hour or less and preferably 30 minutes or less. The method according to the invention comprises bringing the premix formed into contact with a fraction s2 of the reaction solvent, the fraction s2 of the reaction solvent being preheated, to form a reaction mixture brought almost instantaneously to a temperature T1 ranging from 40°C to 80°C. For the purposes of the invention, the term “reaction mixture” refers to the reaction medium in which all or part of the premix formed has been brought into contact with all or part of the fraction s2 of preheated reaction solvent. The polymerization reaction, non-existent or at least very limited kinetically at T0, accelerates substantially at T1. It is marked by a sudden increase in the heat flux emitted by the reaction mixture. It is also marked by a sudden increase in the production of hydrogen chloride.It is finally marked by a rapid increase in the viscosity of the reaction mixture. T1 is equal to 40°C or more. Indeed, for temperatures below 40°C, there is an excessive formation of gels / fouling, which considerably reduces the yield of the process and / or the quality of the polymer obtained. T1 may in particular be greater than or equal to 42°C, or greater than or equal to 44°C, or greater than or equal to 46°C, or greater than or equal to 48°C. According to certain embodiments, T1 has a value of 40°C to 50°C. According to certain embodiments, T1 has a value strictly greater than 40°C. According to certain embodiments, T1 has a value strictly greater than 50°C. T1 is equal to 80°C or less. Indeed, for temperatures above 80°C, the polymer obtained comprises a high fraction of low mass molecules, even after purification.T1 may in particular be less than or equal to 78°C, or less than or equal to 76°C, or less than or equal to 74°C, or less than or equal to 72°C, or less than or equal to 70°C. According to certain embodiments, T1 has a value of 70°C to 80°C. According to certain embodiments, T1 has a value strictly less than 80°C. According to certain embodiments, T1 has a value strictly less than 70°C. According to certain embodiments, T1 has a value of 50°C to 60°C. T1 may in particular have a value of 52°C to 60°C. According to certain embodiments, T1 has a value of 60°C to 70°C. T1 may in particular have a value of 60°C to 68°C. The fraction s2 of reaction solvent is calculated relative to the total reaction solvent that was added at the end of polymerization. The fraction s2 of the reaction solvent may be 0.25 to 0.75. The fraction of the solvent s2 may be 0.25 to 0.35, or 0.35 to 0.45, or 0.45 to 0.55, or 0.55 to 0.65, or 0.65 to 0.75.According to certain embodiments, s1+s2≥ 0.75. Advantageously s1+s2≥ 0.85. In particular, it is possible to have s1+s2≥ 0.90 or s1+s2≥ 0.95. According to particular embodiments, s1+s2= 1, i.e., the entire reaction solvent has been introduced once the reaction mixture at T1 is formed. According to certain embodiments, s1 is from 0.25 to 0.45, s2 is from 0.55 to 0.75, and s1+s2≥ 0.75. According to certain embodiments, s1 is from 0.45 to 0.65, s2 is from 0.35 to 0.55, and s1+s2≥ 0.75. In some embodiments, s1 is from 0.55 to 0.75, s2 is from 0.25 to 0.45, and s1+s2≥ 0.75. In some embodiments, s1 is from 0.25 to 0.45, s2 is from 0.55 to 0.75, and s1+s2=1. In some embodiments, s1 is from 0.45 to 0.65, s2 is from 0.35 to 0.55, and s1+s2=1. In some embodiments, s1 is from 0.55 to 0.75, s2 is from 0.25 to 0.45, and s1+s2=1.Preferably, the premix formed is gradually poured into all or part of the fraction s2 of preheated reaction solvent at a rate suitable for the temperature of the reaction medium to remain within the temperature range imposed for T1 to form the reaction mixture. According to certain embodiments, the premix formed is gradually poured into the entire fraction s2 of preheated reaction solvent. In this embodiment, the fraction s2 of solvent is generally preheated to a temperature within the temperature range imposed for T1. In order for the reaction mixture to remain within the temperature range imposed for T1 to form the reaction mixture, an additional heat flow may be provided by means of heating and / or cooling the reactor. According to certain embodiments, the fraction of solvent s2 may be subdivided into two sub-fractions s2' and s2", such that s2=s2'+s2".According to these embodiments, the premix formed can be gradually poured into the fraction s2' of preheated reaction solvent generally preheated to a temperature in the temperature range imposed for T1. The solvent fraction s2'' is preheated to a temperature higher than that of the fraction s2', for example to a temperature of 80°C to 120°C, is gradually poured at the same time as the premix formed, into the reaction medium so that the reaction mixture remains in the temperature range imposed for T1. In order for the reaction mixture to remain in the temperature range imposed for T1 to form the reaction mixture, an additional heat flow can also be provided by means of heating and / or cooling the reactor. Preferably, s2'' ≤ s2'.The contacting step to obtain the reaction mixture at T1 ends, or in other words the reaction mixture is formed, when the entire premix at T0 and fraction s2 of the reaction solvent have been brought into contact. For the purposes of the invention, when it is indicated that the contacting of the premix formed with fraction s2 of solvent to obtain a reaction mixture at T1 and / or that the reaction mixture formed is maintained at T1, this does not presuppose that the temperature remains fixed, but means that the temperature of the reaction medium remains within the temperature range imposed for T1. The reaction mixture formed may be maintained at T1 for a certain period of time, for example to achieve a determined degree of polymerization. Preferably, the contacting step to obtain the reaction mixture at T1 is carried out with stirring so that the premix formed disperses suitably in the preheated reaction solvent fraction.Advantageously, the stirring is implemented by a double-flow stirring system making it possible to keep the reaction mixture moving, in particular at the side walls of the reactor, and / or using a tank bottom turbine making it possible to keep the reaction mixture moving, in particular at the tank bottom wall, and thus avoiding accelerated fouling of the reactor. The contacting step to form the reaction mixture at T1 generally lasts from 15 minutes to 3 hours, and preferably from 25 minutes to 60 minutes. Once the reaction mixture has been formed at T1, the reaction medium can optionally be maintained at T1 for 0 minutes to 6 hours, and preferably from 10 minutes to 60 minutes. Preferably, the maintenance at T1 of the reaction mixture formed is carried out with stirring.According to certain embodiments, the reaction mixture is maintained at T1 during the contacting step and during the optional step of maintaining the reaction mixture formed for 15 minutes to 8 hours, and preferably for 30 minutes to 120 minutes. The reaction mixture can be maintained at T1 during the step of contacting the premix formed with the fraction s2 of preheated reaction solvent and optionally during the step of maintaining the reaction mixture formed at T1 so as to achieve a certain conversion rate of the reactants of the polymerization reaction. This conversion rate can be evaluated in various ways: assay of the remaining monomers in the reaction medium, measurement of the hydrogen chloride produced during the polymerization reaction, viscosity of the reaction medium, or evaluation of the fraction in percent of the molecular masses strictly less than 500 g / mol as set out below.Preferably, the reaction mixture is maintained at T1 during the step of bringing the premix formed into contact with the fraction s2 of preheated reaction solvent and optionally during the step of maintaining the reaction mixture at T1, until the fraction in percent of molecular masses strictly less than 500 g / mol in PMMA equivalent in the reaction mixture is less than or equal to 50%, preferably less than or equal to 25%, and more preferably less than or equal to 15%. According to certain embodiments, the reaction mixture is maintained at T1 during the step of bringing the premix formed into contact with the fraction s2 of preheated reaction solvent and during the step of maintaining at T1 until the desired degree of polymerization is obtained.According to certain embodiments, after the formation of the reaction mixture at T1 and the optional maintenance of the reaction mixture at T1, the reaction mixture can be brought to and maintained at T2 for a certain period of time, T2 being in the temperature range from a temperature at least 10°C higher than T1 to a temperature of 120°C, so as to achieve the desired degree of polymerization. To do this, an additional heat flux can be provided by means of heating the reactor and / or by the addition of a fraction s3 of preheated reaction solvent, generally at a temperature in the temperature range imposed by T2. This optional step makes it possible to achieve the desired degree of polymerization more quickly than in the embodiments where the reaction mixture is only maintained at T1.In these embodiments, T2 preferably ranges from 80°C to 120°C, more preferably from 82°C to 105°C, and extremely preferably from 85°C to 95°C. According to advantageous embodiments, the hydrogen chloride produced during the polymerization reaction is extracted from the reactor during the polymerization so as to promote the polymerization reaction. For this purpose, all or part of the polymerization may be carried out under reduced pressure, at an absolute pressure of less than or equal to 900 mbar, or less than or equal to 800 mbar, or less than or equal to 700 mbar, or less than or equal to 600 mbar, or less than or equal to 500 mbar, or less than or equal to 400 mbar, or less than or equal to 300 mbar, or less than or equal to 200 mbar, or less than or equal to 100 mbar. Alternatively, or in addition, bubbling of an inert gas, for example helium, argon or nitrogen, is implemented in the reaction mixture.This method is nevertheless not preferred since it creates additional turbulence in the reaction mixture and makes temperature control within the reactor more difficult to control. The process can be carried out in one reactor or a succession of several reactors. According to advantageous embodiments, the contacting to form the premix at T0 and the contacting to form the reaction mixture at T1 are carried out in two separate reactors. In embodiments where the reaction mixture is then brought to T2, this step can be carried out in the same reactor as that used for the contacting to form the reaction mixture at T1. Reactors that can be used to implement the present invention can, for example, be glass reactors, enameled reactors or reactors having corrosion-resistant metallurgy.The reactors preferably have temperature control means and temperature measurement means inside them. The reactors may in particular comprise one or more temperature sensors inside them and be configured to cool and / or heat the medium they contain. The reactors that can be used to implement the present invention are preferably provided with a stirring device such as a mechanical stirrer (which may, for example, comprise one or more stirring rotors) or a recirculation loop with a pump. The reactor that can be used to implement the step of forming the reaction mixture at T1 advantageously has a double-flow stirring system. After the polymerization reaction has been completed to the desired degree of polymerization, the process of the invention may comprise a purification of the polyetherketoneketone from the product mixture, in a manner known per se.This has for example already been described in document EP3655458. This purification makes it possible in particular to separate the solvent, the catalyst, the unreacted reagents, as well as any reaction by-products from the polymer as such. In particular, the purification generally comprises a step of bringing the mixture of products into contact with a protic solvent, so as to recover a first phase comprising the Lewis acid and a second phase comprising the polyetherketoneketone. The protic solvent may be an aqueous solution. The aqueous solution may simply be water. Alternatively, the aqueous solution may be an acidic solution, such as a hydrochloric acid solution. Preferably, the pH of the aqueous solution is not higher than 3, or not higher than 2. The dissociation of the polyetherketoneketone-Lewis acid complex is more efficient when an acidic solution is used.Mixtures of solvents, such as an aqueous-organic solvent, for example an aqueous solution mixed with methanol, ethanol, isopropanol or acetic acid, may also be used. Preferably, a mixture of an aqueous solution and an alcohol, in particular methanol, ethanol, or isopropanol, comprising 95 to 60% by weight, preferably 80 to 95% by weight of alcohol, is used. Contacting the product mixture with the protic solvent results in a first phase (containing the protic solvent) and a second phase (containing the reaction solvent). The Lewis acid is mainly present in dissolved form in the first phase while the polyetherketoneketone is mainly present in precipitated form in the second phase. The polyetherketoneketone can then be recovered by solid / liquid separation of the second phase.Advantageously, the solid / liquid separation is carried out by centrifugal filtration. The dry solid content of raw polyetherketoneketone product at the end of the solid / liquid separation step is preferably between 10% by weight and 90% by weight, more preferably between 15% and 75% by weight and more preferably between 20% and 50% by weight. The liquid effluents, containing the first phase and the second phase, may optionally be separated so as to be recovered separately, preferably by decantation, for possible reuse. A surfactant may be added to facilitate phase separation. When the Lewis acid is aluminum trichloride, the first phase advantageously contains it in proportions adapted so that it can be directly recycled by use in a water treatment / sludge flocculation process.According to preferred embodiments, the crude polyetherketoneketone product from the preceding solid / liquid separation step can be further purified by washing with one or more protic solvents. The protic solvent at this stage is preferably water or an aqueous solution. However, in other variants, the protic solvent at this stage can also be an organic solvent, optionally mixed with water. Linear or branched aliphatic alcohols such as methanol, ethanol and isopropanol are particularly preferred organic solvents. These organic solvents can optionally be mixed with each other and / or with water. After the washing step or concomitantly with the washing step, a further solid / liquid separation step can be carried out.According to an advantageous embodiment, a centrifugal filtration device is used, so that the washing and the solid / liquid separation can be carried out concomitantly in the device, without resuspension of the product. After the last solid / liquid separation, the recovered solid is advantageously dried. The drying step can be carried out in a conventional manner, for example at a temperature ranging from 100°C to 280°C, and under atmospheric pressure or, preferably, under reduced pressure, for example at a pressure of 30 mbar. After drying, the polyetherketoneketone generally has a proportion of reaction solvent of less than or equal to 50 ppm, preferably less than or equal to 30 ppm, and more preferably less than or equal to 15 ppm by weight, relative to the weight of polymer.The polymer, capable of being manufactured according to the process of the invention, generally has an inherent viscosity, measured at a concentration of 0.0005 g / mL in a 96.00% (mass fraction) sulfuric acid solution at 25°C using a suspended level Ubbelohde type viscometer (inner diameter of the capillary of 1.03 mm) according to the ISO 307-2009 standard applied to PEKK, of 0.4 to 2.0 dL / g, and preferably of 0.75 to 1.45 dL / g. In some embodiments, the polyetherketoneketone has an inherent viscosity of 0.75 to 0.85 dL / g, or 0.85 to 0.95 dL / g, or 0.95 to 1.05 dL / g, or 1.05 dL / g to 1.15 dL / g, or 1.15 to 1.25 dL / g, or 1.25 to 1.35 dL / g, or 1.35 to 1.45 dL / g.The polyetherketoneketone, capable of being manufactured according to the process of the invention, has the advantage of generally not containing any dispersing agent(s), in particular those described in WO 9523821 and in US 20120263953, in the form of impurity(ies) (except in the less advantageous embodiments where a dispersing agent would be used). The polyetherketoneketone according to the invention therefore generally does not comprise benzoic acid or one of its derivatives, used as a dispersant, as described in US 20120263953. The polyetherketoneketone in particular generally does not contain one of the following compounds: benzoic acid, methylbenzoic acid, sodium benzoate, magnesium benzoate, aluminum benzoate, methyl benzoate and benzenesulfonic acid. The polyetherketoneketone in particular generally does not contain benzoic acid.The polyetherketoneketone according to the invention therefore generally does not comprise any other polymer, used as a dispersant, such as the polymers described in WO 9523821. The polyetherketoneketone in particular generally does not contain copolymers of aliphatic vinyl compounds and N-vinyl pyrrolidone. The polyetherketoneketone, capable of being manufactured according to the process of the invention, consists of three fractions A, B and C of molecular masses, in which A represents the fraction in percent of the molecular masses strictly less than 500 g / mol, B represents the fraction in percent of the molecular masses ranging from 500 g / mol to 3000 g / mol, and C represents the fraction in percent of the molecular masses strictly greater than 3000 g / mol, in PMMA equivalent. We have A+B ≤ 5.0% and A + B + C = 100%. We preferably have A ≤ 1.0%.Very low molecular weight molecules can be removed to very low levels by more or less sophisticated methods known to those skilled in the art. An azeotropic distillation method has for example been described in WO2014013202. Preferably, in particular thanks to the use of such methods, A ≤ 0.5%, or even A ≤ 0.3%. Preferably, B ≤ 4.0%. Low molecular weight molecules are difficult to remove by even advanced and / or sophisticated extraction methods (see example 3). The method according to the invention makes it possible, according to advantageous embodiments, to achieve B ≤ 3.5%, and preferably B ≤ 3.2%. According to certain advantageous embodiments, one can have B ≤ 3.2, or B ≤ 3.1, or B ≤ 3.0, or B ≤ 2.9, or B ≤ 2.8, or B ≤ 2.7, or B ≤ 2.6, or B ≤ 2.5, or B ≤ 2.4, or B ≤ 2.3, or B ≤ 2.2, or B ≤ 2.1, or B ≤ 2.0.Such polymers having a low B fraction have the advantage of being able to be extruded, in particular granulated, and of making it possible to obtain objects derived therefrom having few defects, in particular few black spots. According to certain embodiments, in particular when T1 is from 68°C to 80°C, there is B ≤ 3.8%, preferably B ≤ 3.5%, and more preferably B ≤ 3.2%. According to certain embodiments, in particular when T1 is from 60°C to 68°C, B ≤ 3.2%, or B ≤ 3.1%, or B ≤ 3.0%. According to certain embodiments, in particular when T1 is from 52°C to 60°C, B ≤ 3.0%, or B ≤ 2.9%, or B ≤ 2.8%. According to certain embodiments, in particular when T1 is from 40°C to 52°C, B ≤ 2.8%, or B ≤ 2.7%, or B ≤ 2.6%. The polyetherketoneketone obtained according to the process of the invention is generally in the form of flakes of fairly uniform size forming a powder. In particular, and advantageously, the polymer has few large flakes.This is particularly advantageous for implementing purification in an easier manner. Indeed, the extraction of aluminum chloride and / or impurities resulting from the polymerization is simpler and more efficient to implement on particles of reduced size. In addition, drying can also be implemented more quickly. Furthermore, feeding equipment for grinding, sieving, compacting, granulating, extruding from such a powder is facilitated. Advantageously, the polyetherketoneketone powder according to the invention has a mass proportion of particles of size strictly greater than 1000 micrometers less than or equal to 50%, relative to the total weight of the particles of the powder, as obtained by sieving using a sieve with a mesh size equal to 1 millimeter.According to certain embodiments, the polyetherketoneketone powder according to the invention has a mass proportion of particles of size strictly greater than 1000 micrometers of less than or equal to 25%. According to certain embodiments, the mass proportion of particles of size strictly greater than 1000 micrometers is less than or equal to 15%, preferably less than or equal to 10%, and extremely preferably less than or equal to 5%. According to certain embodiments, the mass proportion of particles of size ranging from 315 micrometers to 1000 micrometers is greater than or equal to 50%, as obtained by successive sieving using a sieve with a mesh size equal to 1 millimeter and a sieve with a mesh size equal to 315 micrometers. Preferably, the mass proportion of particles of size ranging from 315 micrometers to 1000 micrometers may be greater than or equal to 80%.According to these embodiments, the mass proportion of particles with a size strictly less than 315 micrometers is advantageously less than or equal to 10% and the mass proportion of particles with a size strictly greater than 1000 micrometers is less than or equal to 10%. According to certain embodiments, the mass proportion of particles with a size strictly less than 630 micrometers is greater than or equal to 50%, preferably greater than or equal to 70%, and more preferably greater than or equal to 85%. According to certain embodiments, the polyetherketoneketone flakes, forming a powder, have a packed density greater than or equal to 180 kg / m. 3 . Preferably, the polyetherketoneketone scales, forming a powder, have a packed density greater than or equal to 200 kg / m 3. A sufficiently high tamped density has several advantages depending on the intended uses. In granulation, this reduces the amount of air introduced into the extruder and improves the melt stability of the polymer. In laser sintering, this improves the cohesion of the powder bed after grinding into a fine powder. The tamped density generally remains below 400 kg / m 3 . It can in particular be less than 350 kg / m 3 , or less than or equal to 300 kg / m 3 , or less than or equal to 250kg / m 3. Measurement methods The following measurement methods apply to the invention and have been implemented in particular in the examples presented below. Determination of fractions A, B and C Approximately 30 mg of polymer composition to be evaluated are introduced into 1 ml of 4-chlorophenol for 2 hours at 150°C. After cooling the solution to room temperature, 14 ml of hexafluoroisopropanol (HFIP) are added, then the solution is filtered through an Acrodisc type syringe filter comprising a polytetrafluoroethylene (PTFE) membrane with a diameter of 25 mm and a porosity of 0.2 μm. The molar masses of the resin in the sample are determined by size exclusion chromatography using a Waters Alliance 2695 type instrument using the following conditions: - Flow rate: 1.00 ml / min. Eluent: HFIP. Injected volume: 100.00 μl. Set of PSS PFG columns (1000 + 100 Å) 252*30cm. Temperature 40°C. Detection mode: differential refractometer.- Calibration: PMMA with a molecular mass range from 402g / mol to 1900000g / mol to be updated during each analysis series. The baseline and integration of the chromatograms were carried out following the recommendations of the ISO 16014-1:2019 Standard, namely: - the start of the baseline is generally established at an elution volume between 0 and 10mL (Vi), - the end of the baseline is generally established at an elution volume between 30 and 40mL (Vf). The integration of the chromatogram (area) begins when the signal is distinguished from the 0 level defined by the baseline, called (Va). The integration of the chromatogram (area) ends before the system peak, generally at an elution volume corresponding to a mass between 50 and 200 g / mol in PMMA equivalent (Vb).The integration of masses below 500 g / mol begins at the elution volume corresponding to a molar mass of 500 g / mol in PMMA equivalent (V500) and ends at the final integration level of the chromatogram, namely Vb. The integration of masses below 3000 g / mol begins at the elution volume corresponding to a molar mass of 3000 g / mol in PMMA equivalent (V3000) and ends at the final integration level of the chromatogram, namely Vb.The determination of the molar mass fraction strictly less than 500 g / mol (in PMMA equivalent), noted in the invention as fraction A and expressed in %, is determined by making the ratio of the integration area of ​​the molar masses between 0 and 500 g / mol and the integration area of ​​the total chromatogram, according to the calculation below: [Math 1] The determination of the molar mass fraction ranging from 500 g / mol (in PMMA equivalent) to 3000 g / mol (in PMMA equivalent), noted in the invention as fraction B and expressed in %, is determined by making the following calculation: [Math 2]. The determination of the molar mass fraction strictly greater than 3000 g / mol (in PMMA equivalent), noted in the invention fraction C and expressed in %, is determined by making the following calculation: [Math 3] Measurement of the inherent viscosity The inherent viscosity η inhwas measured at a concentration of 0.0005 g / mL in 96.00% sulfuric acid solution at 25°C using a suspended-level Ubbelohde-type viscometer according to ISO 307-2009. Determination of the size distribution of The particle size distribution was evaluated by sieving on sieves with a mesh size equal to the indicated limit value (315 µm, 630 µm, 800 µm and 1000 µm). Measurement of the tapped density The tapped density was measured according to ISO 1068-1975(F), adapted as follows. - Condition the powder for 24 hours at 23°C and 50%RH; - Introduce a volume of powder (scales) into a 250 ml graduated precision glass cylinder; - Level, if necessary, the free surface of the powder without tamping it and note the volume V0; - Weigh the cylinder with the powder with a precision balance to 0.1 g, the tare of which has been previously carried out; - Place the cylinder on the tray of the STAV 2003 type tamping apparatus; - Pack with 1250 scraps, note the volume V1; - Pack with 1250 scraps, note the volume V2; - Repeat the packing operation until you obtain two equivalent volumes Vi. - Note Vf corresponding to the identical volumes Vi.The tapped density is the mass of powder introduced divided by Vf. It is expressed in kg / m. 3Examples Example 1 Two double-jacketed reactors (R1 and R2), each connected to a thermal regulation system by means of a suitable heat transfer liquid and each equipped with a stirring means and an inerting system under a nitrogen flow in the overhead, were used. In reactor R1, having glycolated water as heat transfer liquid, the premixing was carried out as follows: ortho-dichlorobenzene and 1,4-bis(4-phenoxybenzoyl)benzene were first added with stirring in a mass proportion 1,4-bis(4-phenoxybenzoyl)benzene / ortho-dichlorobenzene equal to 0.128 (fraction s1=0.68).A mixture of terephthaloyl and isophthaloyl chlorides, in a molar proportion of terephthaloyl chloride to isophthaloyl chloride equal to 0.77, was then added with stirring to the reaction medium so that the total amount of isophthaloyl chloride and terephthaloyl chloride was in a substantially equimolar amount relative to 1,4-bis(4-phenoxybenzoyl)benzene (molar proportion of 1,4-bis(4-phenoxybenzoyl)benzene relative to the mixture of terephthaloyl and isophthaloyl chlorides equal to 1.03). Benzoyl chloride was also added with stirring as a chain limiter in a molar proportion relative to 1,4-bis(4-phenoxybenzoyl)benzene equal to 0.042. The reaction medium in reactor R1 was then cooled to -5°C.Solid aluminum trichloride was added over approximately 1 hour with stirring to form a premix, with the temperature of the premix being maintained at around -5°C throughout the aluminum trichloride addition step. The molar ratio of aluminum trichloride to 1,4-bis(4-phenoxybenzoyl)benzene is 6.3. At the end of the aluminum trichloride addition, the temperature of the premix in R1 was maintained at around -5°C for 30 minutes. In parallel, in reactor R2, having oil as heat transfer liquid and equipped with a stirring system with two stirring rotors, ortho-dichlorobenzene was added in a mass proportion of 1,4-bis(4-phenoxybenzoyl)benzene in the premix compared to ortho-dichlorobenzene in R2 equal to 0.060 (fraction s2=0.32) and brought to a temperature of 55°C (test #1), 65°C (test #2) or 90°C (test #3, comparative).The premixture in R1 at 0°C was gradually transferred using a pump into reactor R2 under stirring and maintained at 55°C (test #1), 65°C (test #2) and 90°C (test #3, comparative). The transfer operation lasted 30 minutes. The reaction mixture formed was then maintained at 55°C (test #1), 65°C (test #2) and 90°C (test #3, comparative) for 10 minutes, 10 minutes and 40 minutes, respectively. For tests #1 and #2, the temperature in reactor R2 was then rapidly increased until reaching a temperature of 90°C. The reaction mixture was then maintained at the temperature of 90°C for a period of 30 minutes. For tests #1, #2 and #3, the product mixture was finally cooled to a temperature of approximately 50°C. It was purified by mixing with aqueous hydrochloric acid solution having pH ≤ 3 and solid / liquid separation using a filter.The crude polymer was then washed three times by resuspension and filtration, the washing solutions successively used being methanol, a 3% vol hydrochloric acid solution and water. The purified polymer was finally dried at 180°C for 24 hours under vacuum (30 mbar). The determination of fractions A, B and C as well as the measurement of the inherent viscosity for the polymer composition obtained for each test are presented in Table 1 below: [Table 1].

[0002] The particle size distribution for each test is reported in the graph of Figure 1. Based on the results presented in Table 1, it can be concluded that the polymers according to Examples #1 and #2 have fewer low molecular weight molecules, notably fewer molecules with a molecular weight less than or equal to 3000 g / mol, and notably fewer molecules with a molecular weight of 500 g / mol to 3000 g / mol, than the polymer according to Comparative Example #3. Based on the results presented in Figure 1, it can be concluded that the powder according to Examples #1 and #2 is a submillimeter powder, with a fairly homogeneous particle size distribution, unlike the powder according to Comparative Example #3 which is a powder with particle sizes in the millimeter range and a very inhomogeneous particle size distribution.Example 2 The kinetics of the polymerization reaction was studied at 65°C by preparing the premix at T0 as in Example 1. In parallel, in reactor R2, having an oil as heat transfer liquid and equipped with a double-flow stirring system, ortho-dichlorobenzene was added in a mass proportion of 1,4-bis(4-phenoxybenzoyl)benzene in the premix relative to ortho-dichlorobenzene in R2 equal to 0.060 (fraction s2=0.32) and brought to a temperature of 65°C. The premix in R1 at 0°C was gradually transferred using a pump into reactor R2 under stirring and maintained at 65°C. The transfer operation lasted 30 minutes. The reaction mixture formed was then maintained at 65°C for 90 minutes and samples of reaction medium were taken and analyzed for different holding times to determine fraction A (see Figure 2).In view of Figure 2, it can be deduced that for test #2, according to example 1, the step of contacting to form the premix and maintaining at T1 allows the reaction medium to reach a fraction A of less than approximately 20% for a holding time of 10 minutes. This demonstrates that although the polymerization can be maintained at T1 until reaching the desired degree of polymerization, it may be advantageous to increase the temperature of the reaction medium to a temperature T2 so as to reach the desired degree of polymerization more quickly while benefiting from the technical advantages of the invention (low proportion of low molecular weight molecules and powder morphology). Example 3 An extraction test of fraction B of the polymer obtained according to test #3 was carried out in dichloromethane with stirring for 144 hours at 35°C.The mixture of polymer and extracting dichloromethane was then drained, washed in situ with dichloromethane, then washed with water at 30 °C, and finally dried. The polymer thus extracted has a B fraction of 3.81%. This shows that even under fairly advanced extraction conditions, it is substantially impossible to extract low-mass molecules, particularly those with a molecular weight between 500 g / mol and 3000 g / mol.

Claims

CLAIMS 1. A process for manufacturing a polyetherketoneketone comprising: - bringing into contact an aromatic ether being diphenyl ether, 1,3-bis(4-phenoxybenzoyl)benzene, 1,4-bis(4-phenoxybenzoyl)benzene or their mixture, an acyl chloride being isophthaloyl chloride, terephthaloyl chloride, or their mixture, a Lewis acid, and a first fraction s 1 of a reaction solvent, so as to form a premixture at a temperature T 0 less than or equal to 25°C; - optionally, maintaining at T 0 of the premix formed; - bringing the premix formed into contact with T 0 with a fraction s 2 of the reaction solvent, the fraction s 2 of reaction solvent being preheated, so as to form a reaction mixture brought to a temperature T 1 ranging from 40°C to 80°C; and, - optionally maintaining at T 1, of the reaction mixture formed.

2. The method of claim 1, wherein the reaction solvent is selected from the group consisting of: ortho-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2,3-trichlorobenzene, ortho-difluorobenzene, and mixtures thereof.

3. The method of any one of claims 1 and 2, wherein the reaction solvent is ortho-dichlorobenzene.

4. The method of any one of claims 1 to 3, wherein the Lewis acid is selected from the group consisting of: aluminum trichloride, aluminum tribromide, antimony pentachloride, antimony pentafluoride, indium trichloride, gallium trichloride, boron trichloride, boron trifluoride, zinc chloride, ferric chloride, stannic chloride, titanium tetrachloride, molybdenum pentachloride, and mixtures thereof.

5. A method according to any one of claims 1 to 4, wherein the Lewis acid is aluminum trichloride.

6. A process according to any one of claims 1 to 5, wherein the aromatic ether consists essentially of, or consists of, 1,4-bis(4-phenoxybenzoyl)benzene.

7. A process according to any one of claims 1 to 6, wherein s2 ≥ 0.

25.

8. A process according to any one of claims 1 to 7, wherein s 1 ≥ 0.

25.

9. Method according to any one of claims 1 to 8, in which s 1 + s 2 ≥ 0.

75.

10. Method according to any one of claims 1 to 9, in which s 1 + s 2 = 1.

11. A method according to any one of claims 1 to 10, wherein T 1 ranges from 40°C to 52°C.

12. Method according to any one of claims 1 to 10, in T 1 ranges from 52°C to 60°C.

13. A method according to any one of claims 1 to 10, wherein T 1 ranges from 60°C to 68°C.

14. A method according to any one of claims 1 to 10, wherein T 1ranges from 68°C to 80°C.

15. A process according to any one of claims 1 to 14, wherein the reaction mixture is brought, and optionally maintained, at T 1 until the reaction mixture formed has a fraction of molecular masses strictly less than 500g / mol in PMMA equivalent which is less than or equal to 50%, preferably less than or equal to 25%, and even more preferably less than or equal to 15%.

16. Process according to any one of claims 1 to 15, in which the reaction medium is brought to and optionally maintained at a temperature T 2 ranging from a temperature at least 10°C higher than T 1 at 120°C, after the formation step and optionally maintaining the reaction mixture at temperature T 1.

17. Process according to any one of claims 1 to 16, comprising a step of purifying the mixture of products obtained at the end of polymerization.

18. Process according to any one of claims 1 to 17, in which a chain limiting agent is added before the step of forming the reaction mixture brought to a temperature T 1 .

19. Process according to any one of claims 1 to 18, in which the molar ratio of aromatic ether(s) relative to the reaction solvent having been introduced in total into the reaction mixture is: 0.005 to 0.030, preferably: 0.008 to 0.025, and extremely preferably: 0.010 to 0.

022.

20. Process according to any one of claims 1 to 19, in which the premix formed at T 0 is dispersed in all or part of the fraction s 2 preheated reaction solvent to form the reaction mixture brought to T 1.

21. A method according to any one of claims 1 to 20, wherein the step of contacting the premix with the fraction s 2 of reaction solvent is carried out with stirring, and preferably using a double-flow stirring means.

22. Process according to any one of claims 1 to 21, in which the polyetherketoneketone obtained by the process consists of repeating units of formula (I) and of formula (II), the proportion of units of formula (II) relative to the units of formula (I) being from 55:45 to 95:5, the unit of formula (I) having the chemical formula: [Chem 14] (I), and the motif of formula (II) having the chemical formula: [Chem 15] (II).

23. Polyetherketoneketone consisting of three fractions A, B and C of molecular masses, in which A represents the fraction in percent of the molecular masses strictly less than 500 g / mol in PMMA equivalent, B represents the fraction in percent of the molecular masses ranging from 500 g / mol to 3000 g / mol in PMMA equivalent, and C represents the fraction in percent of the molecular masses strictly greater than 3000 g / mol in PMMA equivalent, characterized in that: A+B ≤ 5.0% and A + B + C = 100%.

24. Polyetherketoneketone according to claim 23, in which, B ≤ 4.0%, preferably B ≤ 3.5%, and more preferably B ≤ 3.3%. 25.Polyetherketoneketone according to any one of claims 23 and 24, having an inherent viscosity greater than or equal to 0.4 dl / g, preferably greater than or equal to 0.5 dl / g, preferably greater than or equal to 0.6 dl / g and more preferably greater than or equal to 0.7 dl / g; and / or having an inherent viscosity less than or equal to 2 dl / g, and preferably less than or equal to 1.5 dL / g;. the inherent viscosity being measured at a concentration of 0.0005 g / mL in a 96.00% sulfuric acid solution at 25°C using a suspended-level Ubbelohde type viscometer according to ISO 307-2009.

26. Polyetherketoneketone according to any one of claims 23 to 25, consisting of repeating units of formula (I) and formula (II), the proportion of units of formula (II) relative to the units of formula (I) being from 55:45 to 95:5, the unit of formula (I) having the chemical formula: [Chem 16] and the motif of formula (II) having the chemical formula: [Chem 17] 27. Polyetherketoneketone according to any one of claims 23 to 26, not comprising a dispersing agent.

28. Polyetherketoneketone powder according to any one of claims 23 to 27, for which the mass proportion of particles of size strictly greater than 1000 micrometers is less than or equal to 50%, as obtained by sieving using a sieve with a mesh size equal to 1 millimeter.

29. Polyetherketoneketone powder according to claim 28, for which the mass proportion of particles with a size ranging from 315 micrometers to 1000 micrometers is greater than or equal to 50%, and preferably greater than or equal to 80%.

30. Polyaryletherketone powder according to any one of claims 28 and 29, for which the mass proportion of particles with a size strictly greater than 1000 micrometers is less than or equal to 10%, and preferably less than or equal to 5%.

31. Polyaryletherketone powder according to one of claims 28 to 30, for which the mass proportion of particles with a size strictly less than 315 micrometers is less than or equal to 10%. 32.Polyetherketoneketone powder according to claim 28, for which the mass proportion of particles with a size strictly less than 630 micrometers is greater than or equal to 50%, preferably greater than or equal to 70%, and more preferably greater than or equal to 85%.

33. Polyetherketoneketone powder according to any one of claims 28 to 32 having a tapped density greater than or equal to 180 kg / m. 3 and less than or equal to 400 kg / m 3 .

34. Polyetherketoneketone according to any one of claims 22 to 27 or powder according to any one of claims 28 to 33, obtained according to the process according to any one of claims 1 to 22.

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