[0001] The invention relates to a poly aryl ether ketone (PAEK) to be used in powder form in an additive manufacturing process, layer-by-layer, three-dimensional object by sintering said powder caused by electromagnetic radiation. More particularly, it relates to a composition of poly (aryl ether ketone) (PAEK) low level of volatile compounds.

[0002] The electromagnetic radiation may be infrared radiation or ultraviolet radiation from a laser beam, in the case of laser sintering (also often referred to as "laser sintering" in English terminology), or any other radiation source . The term "sintering" in this description includes all these processes regardless of the type of radiation. Although in the following text, usually we refer to the laser sintering process, which is written for this process is of course valid for other sintering methods.

[Prior art]

[0003] Poly (aryl ether ketones) are well known engineering polymers high performance. They are used for demanding applications in temperature and / or mechanical or chemical. We find these polymers in fields as diverse as aeronautics and aerospace, off-shore drilling, automotive, rail, marine, wind energy, sports, construction, electronics or implants medical. They can be implemented by all implementation thermoplastic technologies, such as molding, compression, extrusion, spinning, dusting or prototyping by sintering.

[0004] Two synthetic routes were used to prepare the poly-aryl-ether-ketones. A first channel resides in a process known as nucleophilic substitution. This process is complex to implement, access to monomers is difficult because you have to prepare special fluorinated or chlorinated monomers. synthesis of the nucleophilic substitution process conditions are also difficult (350 ° -400 ° C in diphenyl sulfone) and the post-reaction treatments are binding (desalting and difficult solvent).

[0005] A second approach resides in a process known electrophilic substitution, which can be driven at high temperature as at ambient temperature. The advantage of this second method is the possibility of polymerizing at moderate temperature (-20 ° C to 120 ° C) which limits side reactions. Furthermore, monomers such as solvents are industrially accessible.

[0006] The latter method is widely described in the literature, for example in US4841013, US4816556, US4912181, US4698393, WO9500446, US471621 1, WO201 1,004,164 or 1,004,164 WO201.

[0007] The electrophilic substitution reaction is carried out between one or more aromatic acid chlorides and one or more aromatic ethers in the presence of a Lewis acid. It takes place in a solvent, sometimes in the presence of a dispersant (US4698393, WO9500446) and is usually done in two phases with a first phase at ambient temperature or even below 0 ° C, then the reaction is completed at a temperature between 0 ° C and 120 ° C depending on the solvent. It can also operate at higher temperatures but this path generates more side reactions. The reaction mixture is then treated with a protic compound, which allows to extract all or part of the Lewis acid. The choice of the protic compound is dependent on the solvent used. In US4841013 and WO201 1004164, US471621 1 US4912181 or WO201 1004164 the solvent used is dichloromethane and the protic compound is water. In US4716556, WO9500446, the solvent is ortho-dichlorobenzene and the protic compound is methanol.

[0008] Although the invention does not limited to this method, only the preferred method of synthesis by electrophilic substitution reaction is described in the following description.

[0009] The laser sintering process is particularly sensitive to gases are emitted. During sintering of a powder of PAEK caused by electromagnetic radiation, the powder is maintained at high temperature, typically at a temperature above 240 ° C and of up to 300 ° C for the PEKK, such as that marketed by Arkema under the reference Kepstan 6000, throughout the piece construction period, which can last several hours to several tens of hours depending on the complexity of the part. Melting the powder PAEK caused by electromagnetic radiation emitted by the laser, generates locally very briefly a peak temperature which may result in the passage of certain vapor components. The all volatile compounds emitted then condenses on the laser lens is dirty. As to measurement of the fouling of the lens, the energy of the laser beam received by the powder tends to decrease. Therefore, if nothing is done to clean the lens, the mechanical properties of parts produced by laser sintering diminish over time, because the more the lens becomes dirty, the more energy of the electromagnetic radiation received by the powder decreases, and less sintering is effective.

[0010] It is therefore necessary to use a composition of PAEK whose content of volatile condensable compounds is low enough to ensure the stability of mechanical properties of the parts during the entire construction cycle, while limiting the cleaning operations lens.

[001 1] Compositions of PAEK low emissions of condensable vapors or fumes, in the construction of three-dimensional parts, are therefore particularly interesting for this application sintering.

[0012] The patent application WO2014013202, filed by the Applicant, discloses a process for preparing poly-aryl-ether-ketone by electrophilic substitution reaction between one or more aromatic acid chlorides and one or more aromatic ethers, in the presence a Lewis acid. This reaction is conducted in an aprotic solvent solubilizing water only very slightly and in two stages. A first phase the reaction is conducted at a temperature between -5 ° C and 25 ° C under stirring, then the reaction is completed at a temperature between 50 and 120 ° C. The PAEK obtained then contacted the reaction medium with water optionally in presence of acid and is separated from the liquid effluent. A washing step of the higher PAEK obtained in water, is used to extract all or part of the Lewis acid. The applicant realized that it is better to avoid alcohol use to perform this washing step, because alcohol contributes to the occurrence of side reactions, which make it less stable. This method therefore allows to obtain a very stable polymer. However, the Applicant has found that the composition of PAEK obtained by this process still generates condensable vapors during sintering, which means that it still contains significant levels of compounds capable of passing in the vapor phase under the effect of radiation electromagnetic. that make it less stable. This method therefore allows to obtain a very stable polymer. However, the Applicant has found that the composition of PAEK obtained by this process still generates condensable vapors during sintering, which means that it still contains significant levels of compounds capable of passing in the vapor phase under the effect of radiation electromagnetic. that make it less stable. This method therefore allows to obtain a very stable polymer. However, the Applicant has found that the composition of PAEK obtained by this process still generates condensable vapors during sintering, which means that it still contains significant levels of compounds capable of passing in the vapor phase under the effect of radiation electromagnetic.

[0013] After analyzing these condensable vapors, it turns out that they still contain compounds based on aromatic ether compounds from hydroxy aluminum complexes.

[0014] The Applicant has therefore sought to further improve the composition of PAEK to reduce the levels of compounds that can vaporize under the action of electromagnetic radiation and scratching the lens of the optical system of the sintering equipment.

[Technical problem]

[0015] The invention therefore aims to remedy at least one of the disadvantages of the prior art. In particular, the invention aims to provide a poly aryl ether ketone ether composition comprising aromatic content and sufficiently low aluminum so that they no longer generate any condensable vapors may foul the lens system optics of the sintering equipment.

[0016] The invention further aims to provide a method for synthesizing a composition of PAEK to eliminate sufficiently compounds liable to vaporize so that they no longer generate any kind of vapor to clog the lens optical equipment for the sintering system.

[0017] Finally, the invention aims to provide a three-dimensional article obtained by sintering a powder of such a composition of PAEK, layer-by-layer, with the aid of electromagnetic radiation, said three-dimensional article having satisfactory mechanical properties and substantially constant over time.

[Brief description of the invention]

[0018] For this, the invention provides a composition of poly (aryl ether ketone) (PAEK), adapted to be used in a three-dimensional object construction method layer-by-layer by sintering caused by radiation electromagnetic, said composition being characterized in that it comprises an aromatic ether content of between 0 and 0.4% by mass and a mass content of aluminum of less than 1000ppm, preferably below 600ppm and more preferably less than 500ppm.

[0019] Such a composition does not generate condensable vapors or amount small enough not to generate fouling of the lens, at the time of sintering.

[0020] According to other optional features of the composition:

- preferably, the aromatic ether content is between 0 and 0.3% by mass,

- more preferably, the aromatic ether content is between 0 and 0.2% by mass and more preferred between 0 and 0.1% by mass,

- the composition further comprises a mass content of aluminum of less than 1000ppm, preferably below 600ppm and more preferably less than 500 ppm and most preferably between 10 and 250 ppm or between 5 and 100 ppm,

- the composition comprises at least the polyether ketone ketone (PEKK), which represents more than 60% by mass, preferably more than 70% by weight of the composition, comprised terminal,

- the composition is a composition of polyether ketone ketone (PEKK),

- the aromatic ether is (1, 4-phenoxybenzoyl) benzene,

- the composition is in powder form.

[0021] For such a composition, the Applicant has discovered, surprisingly, that the composition of PAEK, when synthesized by standard electrophilic substitution reaction, can be washed once with a water / alcohol mixture to to remove aluminum from the Lewis acid.

[0022] More particularly, the composition of the synthesis process comprises contacting one or more aromatic acid chlorides and one or more aromatic ethers in the presence of a Lewis acid in a solvent solubilizing water at a content less than 0.05% by mass to 25 ° C at a temperature between -5 and + 25 ° C with stirring to complete the polymerization at a temperature between 50 and 120 ° C, and then contacting the mixture reaction with water with stirring in eventual presence of acid, separating the poly-aryl-ether-ketone of liquid effluents, washing the poly-aryl-ether ketone in the presence or absence of acid and separate the juice and finally drying the poly-aryl-ether-ketone obtained at a temperature above the glass transition temperature Tg of 20 ° C;and this process is more particularly characterized in that the washing step of the poly-aryl-ether ketone and separation of juice comprises:

- carrying out a first washing with a water / alcohol mixture and separate the juice,

- performing at least one other additional washing with water or acidic water and separate the juice.

[0023] As explained in the document WO2014013202, alcohol is not a desirable solvent to perform the washing step as it is known to cause side reactions. However, when alcohol is mixed with water in weight proportions of between 95 and 60%, preferably between 95 and 80%, the mixture allows both to reduce the content of aromatic ethers, but also the content aluminum without lead to side reactions. Preferably, the alcohol is selected from at least one of the following alcohols: methanol, ethanol or isopropanol.

[0024] The invention further relates to a use of such a composition in powder form in an object built layer-by-process layer by sintering caused by electromagnetic radiation.

[0025] The invention finally relates to a three-dimensional article obtained by sintering a powder layer-by-layer using electromagnetic radiation, said powder being characterized in that its composition is consistent with that described above.

[0026] Other advantages and features of the invention will appear on reading the following description given by way of illustrative and nonlimiting example.

[Description of the invention]

[0027] In the preamble it is stated that the terms "including (e) between" and / or "lower (e)" and / or "greater (e)" used in the context of this description must agree as including the limits mentioned.

[0028] The term "building temperature" means the temperature at which the powder bed, a constituent layer of a three-dimensional object construction, is heated during the sintering process layer-by-layer of the powder.

[0029] The composition of PAEK according to the invention is synthesized from various combinations of di-chlorides of aromatic acids and acid monochlorides and aromatic ethers and / or aromatic biphenyls.

[0030] Preferably one will choose the acid chlorides from the terephthaloyl chloride (TCI) and the disophthaloyie chloride (ICI) or a mixture thereof, in proportions so that the final PAEK structure, there is a ratio of pattern para - dicetophényle / meta-dicetophényle from 100 to 50% and preferably from 85 to 55 %% and more particularly from 82 to 60%.

[0031] The acid monochlorides be selected from benzoyl chloride and benzenesulfonyl chloride.

[0032] Preferably one will choose the aromatic ethers or aromatic biphenyls following: The diphenyl ether, 1, 4- (phenoxybenzoyl) benzene (EKKE), biphenyl, 4-phenoxybenzophenone, 4-chlorobiphenyl, 4- (4-phenoxyphenoxy) benzophenone and 4-biphenyl phenyl ether benzènesulphonylphényl.

[0033] The poly (aryl ether ketones) (PAEK) comprises the following units of formulas:

(- Ar - X -) and (- An - Y -)

in which :

- Ar and An are each a divalent aromatic radical;

- Ar and An can be chosen, preferably, among the 1, 3-phenylene, 1, 4-phenylene, 4,4'-biphenylene, 1, 4-naphthylene, 1, 5-naphthalene and 2, 6- naphthalene;

- X is an electron withdrawing group; it may be chosen preferably from the carbonyl group and the sulfonyl group,

- Y denotes a group selected from an oxygen atom, a sulfur atom, an alkylene, such as -CH 2 - and isopropylidene.

[0034] In these X and Y units, at least 50%, preferably at least 70% and more particularly at least 80% of the X groups are a carbonyl group, and at least 50%, preferably at least 70% and more preferably at least 80% of the Y groups represent an oxygen atom. In one form

preferred embodiment, 100% of the groups X denote a carbonyl group and 100% of the Y groups represent an oxygen atom.

[0035] More preferably, the poly-arylene-ether ketone (PAEK) may be selected from:

- poly-ketone-ether-ketone, also known as PEKK consisting of formula IA units of formula IB and their mixture:

EVEN Formule IB

a poly-ether-ether-ketone, also known as PEEK, comprising units of formula II:

formulas II

The sequences can be totally para (Formula II). Similarly can be introduced partially or completely, sequences meta in these structures at the ethers and ketones according to the two examples of formulas III and IV below:

Formula

Or :

formula IV

Or ortho linkages according to the formula V:

Formule V

a poly-ether-ketone, also known as PEK, comprising units of the formula VI:

Formule VI

Similarly, the sequence can be totally para but it may also introduce sequences meta partially or totally (the formulas VII and VIII):

formulas VII

formula VIII

poly ether ketone ether ketone, also named PEEKK comprising units of formulas IX:

formula IX

Similarly linkage can be introduced in these structures meta level ethers and ketones.

un poly-éther-éther-éther-cétone, également nommé PEEEK, comprenant des motifs de formules X :

Formule X

De la même façon on peut introduire des enchaînements méta dans ces structures au niveau des éthers et des cétones mais aussi des enchaînements biphénols selon la formule XI :

[0036] D'autres arrangements du groupe carbonyle et de l'atome d'oxygène sont également possibles.

[0037] De préférence, les PAEK utilisés dans l'invention sont choisis parmi les PEKK, le PEEK ou les copolymères à base de PEEK, le PEK ou les copolymères à base de PEK.

[0038] Lors de la synthèse de ces Poly-aryl-éther-cétones, par le procédé préféré de réaction de substitution électrophile, on utilise de préférence les acides de Lewis suivant : Trichlorure d'aluminium anhydre, tribromure d'aluminium anhydre, et de manière plus préférée le trichlorure d'aluminium anhydre.

[0039] Les solvants utilisés sont solvants des chlorures d'acide et non solvants du polymère et solubilisant l'eau à une teneur < 0.2% massique, de préférence <0.05% massique. De préférence, il s'agit d'orthodichloro-benzène.

[0040] Les différentes phases du procédé de synthèse peuvent être opérées dans un même réacteur ou une succession de plusieurs réacteurs. Une première phase de la réaction est réalisée à une température entre -5°C et 25°C sous agitation, puis la réaction de polymérisation est achevée à une température comprise entre 50 et 120°C. Le PAEK obtenu est séparé des effluents liquides après mise en contact du milieu réactionnel avec de l'eau en présence éventuelle d'acide. Cette étape de séparation est suivie d'une étape de lavage.

[0041 ] De manière avantageuse, cette étape de lavage consiste à mettre en contact le PAEK synthétisé, par exemple un PEKK, avec un mélange eau/alcool, sous agitation entre 15 et 60°C, de préférence entre 25 et 50 °C et à maintenir cette agitation pendant une heure. Selon une variante, on peut aussi additionner le mélange eau/alcool dans un réacteur après y avoir introduit le PAEK.

[0042] Cette séquence de lavage peut être divisée en plusieurs séquences successives selon la taille de l'équipement utilisé.

[0043] Le mélange eau/alcool utilisé représente de 15 à 50 fois la masse de PAEK à laver. L'eau peut être acidifiée jusqu'à 10% d'acide chlorhydrique pur, de préférence 4%.

[0044] The alcohol is preferably selected from at least one of the following alcohols: methanol, ethanol or isopropanol. He plays the role of solvent and complexing of aluminum and thus promotes elimination.

[0045] The proportions of alcohol in the mixture however, should not be too high so as not to cause the occurrence of side reactions. They must not be too weak either to allow sufficient removal of aluminum.

[0046] A compromise must be reached on the alcohol proportions. Thus, the mass proportions of alcohol in the water / methanol mixture are preferably between 95 and 60%, preferably between 95 and 80%.

[0047] After washing, the reaction mixture is separated from the majority of the juice by a suitable separator.

[0048] The juice is subjected to appropriate treatment, settling, neutralization, distillation and resin treatment to reclaim or recycle in the process.

[0049] The polymer is then subjected to several additional steps of washing with water or acidic water, followed by separation.

[0050] Finally, a polymer of the drying step is performed at a temperature of 20 ° C above the glass transition temperature Tg below 30 mbar.

[0051] The resulting product has an aromatic ether content of between 0 and 0.4% by mass. Preferably, this content is between 0 and 0.3% by mass, and more preferably it is between 0 and 0.2% by mass. The term aromatic ether of less than 500g molecular weight compounds. mol "1 , as ΙΈΚΚΕ whose molar mass of 470g / mol. The weight Al content in the product obtained is in turn less than 1000ppm, preferably less than 600ppm, more preferably less than 500ppm.

[0052] Such a composition may be used in powder form in an object construction method using electromagnetic radiation, in particular laser, of irradiating layer-by-layer powder, according to a

route determined in order to locally melt the poly aryl ether ketone and obtain said object.

[0053] The composition comprises at least the polyether ketone ketone (PEKK), which represents more than 60% by mass, preferably more than 70% by weight of the composition, comprised terminal. 30 to 40% remaining mass may for example be constituted either with other polymers belonging to the family of PAEK, and / or with fibers, such as carbon fibers, glass fibers for example, and / or fillers such as mineral fillers, glass beads or alternatively by carbon blacks, graphites, graphenes, carbon nanotubes.

[0054] The composition of PAEK is preferably a composition of polyether ketone ketone (PEKK), and the aromatic ether is (1, 4-phenoxybenzoyl) benzene (EKKE).

[0055] The composition is in powder form, ready to be used in a sintering process caused by electromagnetic radiation, for producing three-dimensional objects layer-by-layer.

[0056] The invention finally relates to a three-dimensional article obtained by sintering a powder layer-by-layer using electromagnetic radiation, said powder being a powder PAEK having a composition wherein the content of aromatic ether is between 0 and 0.4% by mass. In addition, the mass content of aluminum in the composition is less than 1000ppm, preferably less than 600ppm, more preferably less than 500ppm. Such a powder does not produce, or very little, vapors, so that the lens of the sintering equipment does not clog and three-dimensional articles made from such powder exhibit satisfactory mechanical properties and constant over time .

Examples:

1. Comparison of the state of the lens according to the EKKE content measured on different samples of PEKK

[0057] Protocol for Measuring the content of aromatic ethers:

[0058] The samples are dissolved in a BTF / HFIP mixture in the presence of an internal standard.

[0059] All analyzes were performed on a Varian® 3800 GC equipped with an on-column injector 1041 and an FID detector.

- Colonne: MXT 500 Sim Dist 6m / 320mii / ef = 0,15mii

- Temperature Det (FID) = 400 ° C

- Injector temperature = 1041 controlled at T <40 ° C

- column flow rate (constant flow) = 3ml / min,

- oven Programming = 40 ° C (2min) - "150 ° C to 8 ° C / min

150 ° C (0min) to 330 ° C (Science) à 15 ° C / min

- 330 ° C (0min) 360 ° C (5min) à 25 ° C / min

- Carrier gas = helium

- Injection system: in the column with the injection point located in the regulated portion by the furnace

- Injected volume = 0.5 l

[0060] Sintering tests were performed on three samples of PEKK. A first product A, synthesized and marketed by the OPM under the reference OxPEKK comprises a mass content EKKE measured by GC, 1, 13%. A product B, a PEKK sold by Arkema under the reference 6000 and Kepstan synthesized according to the method disclosed in WO2014013202, a washing only with water, comprises a content EKKE measured by GC, 0.45 %. A third product C, a PEKK Kepstan 6000 synthesized according to the same method as for the product B, but whose

first washing step is performed with a water / methanol mixture in which the proportions by weight alcohol are between 95 and 60%, preferably between 95 and 80%, comprises a content EKKE measured by GC, 0.25% by mass.

[0061] These sintering tests were conducted in a 285 ° C temperature construction. These tests revealed that the first two products A and B generate a significant release vapors during the test (see Table I below). These vapors are found condensed on the lens. The analysis of a sample of this condensate shows the presence of EKKE. In addition to fouling of the machine, the deposit on the lens changes the energy received by the PEKK powder that does not sinter properly and the resulting three-dimensional object then has mechanical properties that diminish over time.

Table I

2. Comparison of the state of the lens according to the content of Al

[0062] The method of determining the aluminum content

Mineralization:

- Weigh 0.5g of the sample in a DigiTube.

- Add 10 ml of nitric acid 67%

- Heat for 2 hours at 99 ° C in a heating block

- Filter through Whatman filter (589/1 125mm diam)

Make up to the mark with a final volume of 25 mL with water Milly Q

Quantification :

- By the ICP / AES optical technique (ICP Vista Pro) Varian

- Standard happened before and after sample drift control

- work wavelength: 396.15 nm for the aluminum element

[0063] Two samples of product B (samples numbered 5 and 6 in Table II below) and four samples of product C (samples numbered 1-4 in Table II below) of Example 1 were compared . The mass aluminum content of each sample was measured by the method described above. The product B, corresponding to a PEKK prior art, comprises an aluminum content of between 1900 and 2000 ppm depending on the sample. The product C, according to the invention comprises an aluminum content ranging from 8 ppm, 9 ppm to 800 ppm depending on the sample.

[0064] Thermogravimetric analysis (TGA) were performed with a Netzsch TG209F1 device. This device consists of two main components: a very sensitive microbalance coupled to a temperature-controlled oven. The microbalance is capable of detecting a variation of 0.1 mg to a maximum capacity of 1, 3 g. The sample is placed in a platinum dish and the beam maintains the balance tray via a current proportional to the supported mass. The temperature is regulated between 30 ° C and 1000 ° C with temperature rises up to 200 "C.min " 1 . A thermocouple near the sample monitors the temperature and controls the heating power. Calibration was performed with the

[0065] All TGA analyzes on the samples were performed isothermally, under nitrogen, at a temperature of 285 ° C, corresponding to the laser sintering Construction temperature for one hour. measured masses losses are shown in Table II below.

ATG isothermal 1 h at 285 ° C under N2 content Al

Samples mass Losses

isothermal% m

1 - Product C 0 8 ppm

2 - Product C 0 9 ppm

3 - Product C 0200 ppm

4 - Product C 0800 ppm

5 - 1900 ppm Product B 0.3

6 - Product B 0.2 2000 ppm

Tableau II

[0066] The weight loss measures by ATG demonstrate a correlation between the thermal stability of the sample of PEKK and its aluminum content. Thus, in the lower aluminum contents to 1000ppm, the PEKK composition is thermally stable.

[0067] The results obtained by TGA show that aluminum samples 5 and 6 of the product B of the prior art, forms complex nature of generating vapor under the effect of temperature, which generate vapors sufficient to foul the lens of the sintering equipment. The product C according to the invention contains sufficiently low aluminum contents not generate vapor, no loss of mass is detected. The lens of the sintering equipment is not fouled at the time of sintering the powder according to the invention PEKK.

[0068] The composition of PAEK according to the invention therefore allows to maintain the sintering equipment and obtain three-dimensional objects with sintered satisfactory and consistent mechanical properties in time.

claims:

1. Poly composition (aryl ether ketone) (PAEK), adapted to be used in a three-dimensional object construction method layer-by-layer by sintering caused by electromagnetic radiation, said composition being characterized in that it comprises an aromatic ether content of between 0 and 0.4% by mass and a mass content of aluminum of less than 1000ppm, preferably below 600ppm and more preferably less than 500ppm.

2. Composition according to claim 1, characterized in that the composition comprises at least the polyether ketone ketone (PEKK), which represents over

60% by mass, preferably more than 70% by weight of the composition, limits included.

3. Composition according to claim 1, characterized in that the composition is a polyether ketone ketone (PEKK).

4. Composition according to one of claims 1 to 2, characterized in that the aromatic ether is (1, 4-phenoxybenzoyl) benzene.

5. Use of a composition according to one of claims 1 to 4, said composition being in powder form, in an object built layer-by-process layer by sintering caused by electromagnetic radiation.

6. three-dimensional article obtained by sintering a powder layer-by-layer using electromagnetic radiation, said powder being characterized in that its composition is in conformity with one of claims 1 to 4.

7. A method of synthesizing a poly (aryl ether ketone) (PAEK) according to one of claims 1 to 4, said method comprising:

- contacting one or more aromatic acid chlorides and one or more aromatic ethers in the presence of a Lewis acid in a solvent solubilizing water at a content of less than 0.05% by mass to 25 ° C at a temperature between -5 and + 25 ° C with stirring,

-achever polymerization at a temperature of between 50 and 120 ° C,

- contacting the reaction mixture with water under agitation in the presence of any acid,

- separating the poly-aryl-ether-ketone of the liquid effluents,

-Wash the poly-aryl-ether ketone in the presence or absence of acid and separate the juice,

- drying the poly-aryl-ether ketone obtained at a temperature above the glass transition temperature Tg of 20 ° C,

said method being further characterized in that the washing step of the poly-aryl-ether ketone and separation of juice comprises:

- carrying out a first washing with a water / alcohol mixture and separate the juice, water / alcohol mixture comprising alcohol in proportions of between 95 and 60% by mass, preferably between 95 and 80% by mass,

- performing at least one other additional washing with water or acidic water and separate the juice.

A method according to claim 7, characterized in that the alcohol is selected from at least one of the following alcohols: methanol, ethanol or isopropanol.