EP4084941A1

EP4084941A1 - Method for manufacturing a product made from polyaryletherketone and corresponding product

Info

Publication number: EP4084941A1
Application number: EP20848860.1A
Authority: EP
Inventors: Jérôme Pascal; Yves Deyrail; Philippe Bussi; Clément PAUL
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2019-12-31
Filing date: 2020-12-18
Publication date: 2022-11-09
Also published as: FR3105794A1; WO2021136904A1; FR3105794B1; US20230089774A1

Abstract

The invention relates to a method comprising: - providing a semi-crystalline or crystallizable composition, having a glass transition temperature T_g comprising at least one polyaryletherketone; - providing a compression-shaping means comprising: a mould (1), the mould having at least one cavity (13); - preparing the composition in the molten state in the at least one cavity, the mould having a temperature T₀ at the end of the preparation step; - compressing and cooling the composition in the molten state, the mould being cooled from the temperature T₀ to a final temperature T_f less than or equal to (T_g+30)°C, in order to form an article shaped by compression; and, - demoulding the compression-shaped article; wherein the composition has a melting temperature strictly lower than 340°C.

Description

Title: Manufacturing process of a poly-aryl-ether-ketone-based product and corresponding product

Technical area

The invention relates to the field of methods for forming by compression of thermoplastics.

More particularly, the invention relates to a process for shaping a composition comprising at least one poly-aryl-ether-ketone.

Prior art

Compression molding is a method of shaping thermoplastic polymers well known to those skilled in the art. The general information mentioned below comes from ROSATO, Dominick V., ROSATO, Donald V., and V ROSATO, Matthew. Plastic product material and process selection handbook. Elsevier, 2004.

In a compression molding process, a polymer is made into a simple shaped product, by heating and applying pressure with a press, in a mold having at least one predefined shaped cavity.

The mold usually consists of two parts. A female part, or mold cavity, is usually mounted on the lower plate of the press, while a male part, or pusher, adapted to match the shape of the female part, is attached to an upper plate of the press. .

A compression molding cycle typically includes the following steps:

1 - the open mold is loaded with thermoplastic polymer in the solid state;

2 - the mold is closed by bringing the pusher against the cavity using the press;

3 - the thermoplastic polymer is melted in the closed mold;

4 - pressure is applied to the molten thermoplastic polymer;

- the molten thermoplastic under pressure is cooled to form a compression molded article;

6 - the compression-molded article is removed from the mold (demoulding). Poly-aryl-ether-ketones are high performance technical polymers also known to those skilled in the art. They can be used for restrictive applications in temperature and / or in mechanical stresses, or even in chemical stresses. They can also be used for applications requiring excellent fire resistance and low emission of fumes and other toxic gases. Finally, they exhibit good biocompatibility. These polymers are found in fields as varied as aeronautics and space, off-shore drilling, automotive, rail, marine, wind power, sports, construction, electronics and even implants. medical.

The compression molding of poly-aryl-ether-ketone has been carried out to date only with a poly-ether-ether-ketone, the phenylene groups of which are all of type 1, 4 phenylene. This polyether-ether-ketone has a melting point of 340 ° C or higher, measured by ASTM D3418. In the process using this polymer, the mold must be heated to a temperature of 400 ° C or more so that the poly-ether-ether-ketone can melt properly. A temperature plateau of sufficient duration is observed at 400 ° C. so that the melt has in particular an almost homogeneous temperature. The mold is then cooled and a high pressure, for example a pressure of 150 bar, is applied to the mold during the whole cooling step, until the temperature of the mold reaches a temperature less than or equal to 150 ° C. The article obtained is then demolded at room temperature.

This process using a poly-eher-ether-ketone in which the phenylene groups are all of type 1, 4 phenylene has several disadvantages.

It requires maintaining the molten polymer at a very high temperature (around 400 ° C) for a long time (end of the heating step, temperature plateau for homogenization, and start of the compression-cooling step). This can generate a phenomenon of thermo-oxidation of the polymer which is caused to degrade. The article obtained consequently exhibits mechanical properties that are less than those expected and / or a change in color compared to the initial polymer of yellowing type and / or color inhomogeneities.

In addition, the process requires cooling over a wide range of temperatures (range of temperatures of the order of 250 ° C.). This wide temperature amplitude of the cooling implies a risk of poor temperature control within the part being cooled (for example a strong temperature gradient between the core and the periphery), which increases the possibility of generating stresses residual mechanics. In addition, due to the wide range of temperatures, the cooling step is generally very long. So that this step is not too long for industrial use, it may be desirable to accelerate the cooling rate, which risks generating more residual mechanical stresses in the structure of the molded article.

There is therefore a need to provide improved processes for shaping by compression of poly-aryl-ether-ketone (s), intended for applications restricting temperature and / or mechanical, or even chemical, stress.

Objectives of the invention

An objective of the invention is to provide an improved process for forming by compression of poly-aryl-ether-ketone (s).

According to at least some embodiments, an objective is to provide a method making it possible to obtain an article having good mechanical properties and / or few residual mechanical stresses.

According to at least some embodiments, an objective is to provide a process for obtaining an article having a homogeneous color.

According to at least some embodiments, an objective is to provide a method for obtaining an article having a high thickness.

According to at least some embodiments, an objective is to provide a method for obtaining a semi-crystalline article.

According to at least some embodiments, an objective is to provide a method which is faster.

Presentation of the invention

The present invention relates to a method of manufacturing an article by compression shaping, comprising: - providing a semi-crystalline or crystallizable composition comprising at least one poly-aryl-ether-ketone, said composition having a glass transition temperature T _g and a melting temperature T _m ;

- the provision of a compression shaping means comprising: a mold and a means for compressing the mold, the mold having at least one cavity and at least one removable wall capable of closing said at least one cavity, the means of compression being adapted to exert pressure on at least said removable wall;

- preparing the composition in the molten state in said at least one cavity, the mold having a temperature To at the end of the preparation step;

- compressing and cooling the composition in the molten state in said at least one cavity, the mold being cooled from temperature To to a final temperature T t less than or equal to (T _g + 30) ° C , to form a shaped article by compression; and,

- the release of the article shaped by compression; in which the composition has a melting point strictly less than 340 ° C, and preferably less than or equal to 335 ° C

In certain embodiments, the composition has a glass transition temperature T _g strictly greater than 145 ° C, preferably greater than or equal to 150 ° C.

In some embodiments, the melt index of the composition has a value of from 1 to 100 cm ^3/10 min, and preferably has a value ranging from 2 to 60 cm ^3/10 min at 380 ° C and a load of 5 kg.

In certain embodiments, the cooling in the “compression and cooling” step is carried out at an average speed of: 0.25 ° C / min to 2.5 ° C / min, and preferably at an average speed of: 0.5 ° C / min at 2 ° C / min between To and Tt.

In certain embodiments, the composition has an isothermal half-crystallization time at a temperature of (T _m -20) ° C greater than or equal to 5 minutes, preferably greater than or equal to 10 minutes, and more preferably greater than or equal to equal to 15 minutes.

In certain embodiments, said at least one poly-aryl-ether-ketone of the composition represents at least 60%, or at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 92.5%, or at least 95%, or at least 97.5%, or at least 98%, or at least 98.5%, or at least 99% or at least 99.5%, or 100% by weight, relative to the total weight of the composition.

In some embodiments, said at least one poly-aryl-ether-ketone is a poly-ether-ketone-ketone.

According to a first variant, said poly-ether-ketone-ketone is a copolymer essentially consisting of, preferably consisting of: a terephthalic unit and an isophthalic unit, the terephthalic unit having the formula:

[Chem 1] the isophthalic unit having the formula:

[Chem 2] the molar percentage of terephthalic unit relative to the sum of the terephthalic and isophthalic units being from 45% to 75%, preferably from 48% to 72%, more preferably from 54% to 66%, and extremely preferably from 58 % to 64%.

According to a second variant, said at least one poly-aryl-ether-ketone is a copolymer comprising a unit of formula:

[Chem 3] and a unit of formula: [Chem 4] the molar percentage in unit (III) relative to the sum of units (III) and (IV) being from: 55% to 95%, and preferably from: 60% to 85%.

According to a third variant, said at least one poly-aryl-ether-ketone is a copolymer comprising a unit of formula:

[Chem 5] and a unit of formula:

[Chem 6] the molar percentage in unit (III) relative to the sum of units (III) and (V) being from: 0 to 95%, preferably from: 40% to 95%, and more preferably from: 70 to 95%

In some embodiments, the composition is provided in the form of granules.

In other embodiments, the composition is provided in the form of a powder having a distribution of particle diameters having a D50 less than or equal to 500 microns, preferably less than or equal to 300 microns, still more preferably less than or equal to 100 microns, and extremely preferably about 50 microns.

In certain embodiments, the preparation of the composition in the molten state in the mold comprises a step of homogenizing the composition in the molten state, the mold being maintained at a temperature To for a sufficient period of time. homogenization. The homogenization time is advantageously short. According to a first variant, the preparation of the composition in the molten state comprises:

filling the cavity with said powder, or said granules, and optionally compacting said powder, or respectively said granules, in the cavity to obtain a cavity filled with powder, or respectively filled with granules; and,

- heating the mold filled with powder, or granules respectively, to temperature To, with To³ (Tm + 10) ° C, in order to melt all of the powder or granules.

According to a second variant, the preparation of the composition in the molten state comprises transferring the already molten composition into the cavity, the mold being maintained at the temperature To, with To £ T _m , in order to obtain a mold filled with composition at the fade state.

In some embodiments, the method also includes a step of annealing the shaped article by compression, to remove any residual stress.

The present invention also relates to an article obtainable by the method described here.

According to some embodiments, the article may have a thickness greater than or equal to 75 millimeters.

According to certain embodiments, the article may have an enthalpy of fusion greater than or equal to 25 J / g (PAEK), preferably greater than or equal to 30 J / g (PAEK), more preferably greater than or equal to 35 J / g (PAEK), as measured by DSC on first heating with a heating ramp of 20 ° C / min.

The present invention overcomes the drawbacks of the prior art. It more particularly provides a process in which the thermo-oxidation phenomena are limited due to the lower melting temperature of the PAEK (s) used. Indeed, the maximum temperature to which the composition comprising at least one PAEK is subjected during the process is substantially lower than that of processes according to the prior art. Furthermore, the amplitude of cooling temperatures is lower, which implies a step of "compression and cooling" generally faster and less likely to generate residual mechanical stresses within the shaped article.

The preferred embodiments make it possible in particular to further reduce the maximum temperature reached during the process, and / or to decrease the time during which the composition is subjected to high temperatures (in particular to temperatures approaching the maximum temperature), and / or to decrease the duration of the compression and cooling step, and / or to promote homogeneous crystallization during the “compression and cooling” step while generating a minimum of stresses.

The method according to the invention and / or the methods according to the preferred modes thus make it possible to obtain articles shaped by compression having good mechanical properties and / or a sufficiently homogeneous color and / or a high and sufficiently homogeneous degree of crystallinity. and / or a high thickness.

Detailed description of the invention

The invention will now be described in more detail and in a nonlimiting manner in the detailed description which follows.

Figures

[Fig. 1] schematically shows a first variant of compression shaping means.

[Fig.2] schematically shows a second variant of compression shaping means.

Definitions

The term “glass transition temperature”, denoted T _g , is understood to denote the temperature at which an at least partially amorphous polymer changes from a rubbery state to a glassy state, or vice versa, as measured by differential scanning calorimetry. (DSC) for second heating using a heating rate of 20 ° C / min, according to ISO 11357-2: 2013. In the present invention, when reference is made to a glass transition temperature, it is more particularly, unless otherwise indicated, the glass transition temperature at half-height of the stage, as defined in this standard. The compositions comprising one or more PAEK (s) may optionally exhibit several glass transition stages in the DSC analysis, in particular due to the presence of several PAEKs having different glass transition temperatures. In this case, the term “glass transition temperature” is understood to mean the glass transition temperature corresponding to the lowest glass transition plateau in temperature.

The term “melting temperature”, denoted Tm, is understood to denote the temperature at which an at least partially crystalline polymer changes to the viscous liquid state, as measured by differential scanning calorimetry (DSC) on the second heating with a speed heating temperature of 20 ° C / min, according to ISO 11357-3: 2018. In cases where a melting point cannot be measured by this method, in particular for compositions which can crystallize more slowly, the composition is first heated to a temperature several tens of degrees higher above its T _g , for example at a temperature of: (T _g +90) ° C, for several tens of minutes, for example for 60 minutes, then heated according to a ramp of 20 ° C / min.

In the present invention, when reference is made to a melting temperature, it is more particularly, unless otherwise indicated, the peak melting temperature as defined in this standard. The powders based on PAEK (s) in the present invention may optionally exhibit several melting peaks in the DSC analysis, in particular due to the presence of different crystalline forms for a given PAEK and / or due to the presence of several PAEKs. different. In this case, the term “melting temperature of the powder” is understood to mean the melting temperature corresponding to the highest melting peak in temperature.

The term “semi-crystalline” is understood to denote a composition which exhibits at a considered temperature one or more crystalline regions, which can be observed by X-rays.

The term “crystallizable” is understood to denote a composition, initially essentially amorphous at an initial temperature, for example at temperature. ambient, capable of forming semi-crystalline region (s) when subjected to heat treatment above its T _g for a sufficient time.

A composition is considered to be semi-crystalline or crystallizable if its enthalpy of fusion is greater than or equal to 1 J / g, preferably greater than or equal to 2 J / g and even more preferably greater than or equal to 5 J / g, as measured by Differential Scanning Calorimetry (DSC) in second heating with a heating rate of 20 ° C / min, according to ISO 11357-3: 2018. In cases where the enthalpy of fusion appears to be strictly less than 1 J / g according to the method cited above, in particular for compositions which can crystallize more slowly, the composition is first heated to a temperature several tens of degrees higher than above its T _g , for example at T _g +90 ° C, for several tens of minutes, for example for 60 minutes, then heated according to a ramp of 20 ° C / rrin. A composition is considered to be semi-crystalline or crystallizable if its enthalpy of fusion is greater than or equal to 1 J / g, preferably greater than or equal to 2 J / g and even more preferably greater than or equal to 5 J / g, as measured according to this second method.

The term “isothermal half-crystallization time”, denoted “t-1/2” at a measurement temperature, is understood to denote the time necessary to reach a relative crystallinity of 0.5 for an isothermal crystallization at the measurement temperature, as defined. according to ISO 11357-7: 2015.

The term “mixture of polymers” is understood to denote a macroscopically homogeneous polymer composition. The term also encompasses such compositions composed of phases which are immiscible with one another and dispersed on a micrometric scale.

The term “copolymer” is understood to denote a polymer resulting from the copolymerization of at least two types of chemically different monomers, called comonomers. A copolymer is therefore formed from at least two different repeating units. It can also be formed from three or more repeat patterns. The acronym "PAEK" corresponds to the notation "poly-aryl-ether-ketone", "PAEKs" to "poly-aryl-ether-ketones" and "PAEK (s)" to "poly-aryl-ether-ketone ( s) ”.

Composition used

The composition comprises at least one poly-aryl-ether-ketone. A poly-aryl-ether-ketone (PAEK) contains the units of the following formulas:

[Chem 7]

(-Ar-X-) and (-An-Y- in which:

- Ar and An each denote a divalent aromatic radical;

- Ar and An can be chosen, preferably, from 1, 3-phenylene, 1, 4-phenylene, 1, 1 '-biphenylene divalent in positions 3,3', Ie1, 1 '-biphenyl divalent in positions 3 , 4 ', 1, 4-naphthylene, 1, 5-naphthylene and 2,6-naphthylene;

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

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

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

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

The weight of PAEK or, where appropriate, the sum of the weights of the PAEKs of the composition generally represents at least 50% of the total weight of the composition. It can in particular represent at least 60%, or at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 92.5%, or at least 95% of the total weight of the composition. .

In certain embodiments, the composition consists essentially of PAEK (s), that is to say it comprises from 95% to 99.9% of the total weight of the composition in PAEK (s). In certain embodiments, the composition consists of PAEK (s) that is to say it consists of at least 99.9%, ideally 100% of the total weight of the composition in PAEK (s) .

The composition has a melting point, T _m , strictly below 340 ° C. Preferably, the composition may have a melting point of less than or equal to 335 ° C.

In certain embodiments, the composition has a melting point of less than or equal to 330 ° C, or less than or equal to 320 ° C, or less than or equal to 310 ° C, or even less than or equal to 305 ° C. Generally, the lower the melting temperature of the composition, the less the composition will be subjected to thermo-oxidation phenomena, the effect of which is harmful on the article obtained at the end of the process. Indeed, a composition having a low melting temperature will generally be subjected to lower temperatures (in particular a lower maximum temperature during the process) than a composition having a higher melting temperature. However, for uses of articles manufactured according to the invention under constraining temperature conditions, an excessively low melting temperature, for example a melting temperature less than or equal to 250 ° C, is generally not desired.

The composition may have a melt index at 380 ° C and under a load of 5kg, from: 1 to 100 cm ^3/10 min as measured according to ASTM D1238-10.

The composition can preferably have a melt index of 2 to 60cm ³ / 10min. Compositions having a viscosity index that is too low may have difficulty in molten flow, making the filling of the cavity and / or the homogenization of the composition in the molten state in the cavity more difficult to carry out. . In unfavorable situations (in particular due to too high a viscosity and insufficient homogenization), an article having porosities may be obtained (undesirable). Regarding compositions having too high a viscosity index, it is generally more difficult to ensure good sealing of the mold once pressure is exerted on the composition in the molten state.

The composition may have a glass transition temperature, T _g , greater than or equal to 125 ° C. A high glass transition temperature value allows to consider uses of the articles manufactured according to the invention under constraining temperature conditions. The glass transition temperature may in particular be greater than or equal to 130 ° C, or greater than or equal to 140 ° C, or greater than or equal to 145 ° C, or greater than or equal to 150 ° C, or even greater than or equal to 155 ° vs.

The difference (Tm-T _g ) is advantageously as small as possible so that the cooling during the process is as short as possible. The difference (Tm-T _g ) is preferably strictly less than 190 ° C.

The difference (Tm-T _g ) may in particular be less than or equal to 185 ° C, or less than or equal to 180 ° C, or less than or equal to 170 ° C, or less than or equal to 160 ° C, or even less than or equal to 150 ° C.

The composition can have an isothermal half-crystallization time at a temperature of (Tm-20) ° C greater than or equal to 5 minutes, preferably greater than or equal to 10 minutes and more preferably greater than or equal to 15 minutes.

The composition can have an isothermal half-crystallization time at a temperature of (Tm-40) ° C greater than or equal to 5 minutes, preferably greater than or equal to 10 minutes and more preferably greater than or equal to 15 minutes.

These isothermal half-crystallization times are particularly advantageous in embodiments, some of which are detailed below, where it is desired that the composition not crystallize too quickly (for example: melting of granules of composition initially in the state. amorphous in a granule compression molding process, or else introduction of molten composition into a mold maintained at a temperature To £ T _m in an extrusion-compression process). However, in order for the composition to be able to crystallize sufficiently during the compression and cooling step, the composition advantageously has an isothermal half-crystallization time at the temperature for which the maximum crystallization rate is sufficiently low relative to the total duration of the l. compression and cooling step.

In some embodiments, the composition comprises, or consists essentially of, or consists of, a single PAEK. In other embodiments the composition comprises, or consists essentially of, or consists of, several PAEKs. Advantageously, the PAEK (s) can be chosen from:

- a poly-ether-ketone-ketone: it comprises a unit (s) of formula: -Ph-O- Ph-C (0) -Ph-C (0) -;

- a poly-ether-ether-ketone: it comprises; a PEEK comprises a unit (s) of formula: -Ph-O-Ph-O-Ph-C (O) -;

- a poly-ether-ketone, also called PEK; a PEK comprises a unit (s) of formula: -Ph-O-Ph-C (O) -;

- a poly-ether-ether-ketone-ketone, also called PEEKK; a PEEKK comprises a unit (s) of formula: -Ph-O-Ph-O-Ph-C (O) - Ph-C (O) -;

- a poly-ether-ether-ether-ketone, also called PEEEK; a PEEEK comprises a unit (s) of formula: -Ph-O-Ph-O-Ph-O- Ph-C (O) -;

- a poly-ether-diphenyl-ether-ketone also called PEDEK; a PEDEK comprises a unit (s) of formula: a PEDEK comprises a unit (s) of the formula -Ph-O-Ph-Ph-O-Ph-C (O) -;

- their mixtures; and,

- their copolymers, in which: Ph represents a phenylene group and -C (O) - a carbonyl group, each of the phenylenes possibly being of the ortho (1 -2), meta (1 -3) or para (1 -4) type ), preferably being of meta or para type.

In addition, defects, end groups and / or monomers can be incorporated in very small amounts in the polymers as described in the list above, without affecting their performance.

According to a first variant, the composition essentially consists of, or even consists of, a poly-ether-ketone-ketone copolymer comprising: a terephthalic unit and an isophthalic unit, the terephthalic unit having the formula:

[Chem 8] the isophthalic unit having the formula: [Chem 9]

For a copolymer, the term "comprises unit (s)" means that this / these unit (s) have a molar proportion of at least 50% in the copolymer. This / these unit (s) may / may represent a molar proportion of at least 60%, or of at least 70%, or of at least 80%, or of at least 85%, or of at least 90%, or at least 92.5%, or at least 95% in the copolymer. The term "essentially consisting of unit (s)" means that G / the unit (s) represent a molar proportion of 95% to 99.9% in the copolymer. Finally, the term "consisting of unit (s)" means that My unit (s) represent a molar proportion of at least 99.9% in the copolymer.

Preferably, the poly-ether-ketone-ketone essentially consists of, or even consists of: isophthalic “I” and terephthalic “T” units. The choice of the molar ratio of T units relative to the sum of T and I units is one of the factors that allows adjustment of the melting temperature and crystallization rate properties of poly-ether-ketone-ketones. A given molar proportion of T units relative to the sum of T and I units can be obtained by adjusting the respective concentrations of the reactants during the polymerization, in a manner known per se.

The molar proportion of T units relative to the sum of the T and I units of PEKK (s) can vary from: 0 to 5%; or from 5 to 10%; or from 10 to 15%; or from 15 to 20%; or from 15 to 20%; or from 20 to 25%; or from 25 to 30%; or from 30 to 35%; or from 35 to 40%; or from 40 to 45%; or from 45 to 48%, or from 48% to 54%, or from 54% to 60%, or from 60% to 66%, or from 66 to 72%; or from 72% to 75%; or from 75 to 80%; or from 80 to 85%; or from 85 to 90%; or from 90 to 95%; or 95 to 100%.

Advantageously, the composition consists essentially of, or even consists of, a poly-ether-ketone-ketone essentially consisting of, or even consisting of, “T” and “I” units, with a molar proportion of T units relative to the sum of the T and I units ranging from 45% to 75%. Indeed, in this range of molar proportions, a poly-ether-ketone-ketone has a melting point strictly below 340 ° C. and suitable crystallization rates between T _g and Tm for use in a process according to the invention. The molar proportion of T units relative to the sum of T and I units is preferably from 48% to 72%, more preferably from 54% to 66%, extremely preferably from 58% to 64%. The molar proportion of T units relative to the sum of T and I units can in particular be approximately 60%. According to a second variant and a third variant, presented below, the composition consists essentially of a constituent unit of poly-ether-ether-ketone comprising only 1, 4-phenylene groups with another repeating unit, making it possible to modulating the values of T _g , Tm and crystallization rates between T _g and Tm relative to a poly-ether-ketone-ketone homopolymer comprising only 1, 4-phenylene groups.

According to the second variant, the composition consists essentially of, or even consists of, a copolymer comprising a unit of formula:

[Chem 10] and a unit of formula: [Chem 11]

Preferably, the copolymer consists essentially of, or even consists of: units of formula (III) and (IV).

Advantageously, the composition consists essentially of, or even consists of, a copolymer essentially consisting of, or even consisting of, units of formulas (III) and (IV) and having a molar proportion of unit (III) relative to the sum units (III) and (IV) ranging from: 55% to 95%. The molar proportion of unit (III) relative to the sum of units (III) and (IV) is preferably from: 60% to 85%, and more preferably from: 65% to 75%. The molar proportion of unit (III) relative to the sum of units (III) and (IV) can in particular be approximately 70%.

According to the third variant, the composition consists essentially of, or even consists of, a copolymer comprising a unit of formula:

[Chem 12] and a unit of formula:

[Chem 13]

Preferably, the copolymer consists essentially of, or even consists of: units of formulas (III) and (V).

Advantageously, the composition consists essentially of, or even consists of, a copolymer essentially consisting of, or even consisting of, units of formulas (III) and (V) and having a molar proportion of unit (III) relative to the sum units (III) and (V) ranging from 0% to 95%. The molar proportion of unit (III) relative to the sum of units (III) and (V) is preferably from 5% to 95%, more preferably from 40% to 95% and extremely preferably from 70% to 95 %. The molar proportion of unit (III) relative to the sum of units (III) and (V) can in particular be: 70% to 75%, or from 75% to 80%, or from 80% to 85%, or from 85% to 90%, or else from 90% to 95%.

According to certain embodiments, the composition may further contain one or more other polymers not belonging to the PAEK family, in particular other thermoplastic polymers.

According to certain embodiments, the composition can further comprise fillers and / or additives. Among the fillers, let us quote reinforcing fillers, in particular mineral fillers such as: talc, carbon black, nanotubes, carbon or not, fibers (glass, carbon, etc.), crushed or not. The composition can thus comprise less than 50% by weight of fillers, preferably less than 40% by weight of fillers and even more preferably less than 25% by weight of fillers, relative to the total weight of the composition.

Among the additives, mention may be made of stabilizing agents (light, in particular UV, and heat such as, for example, phosphate salts), optical brighteners, dyes, pigments, flow agents, additives making it possible to adjust the viscosity. of the composition in the molten state, the additives making it possible to adjust the crystallization rates of the composition between T _g and Tm, the additives making it possible to adjust the heat capacity of the composition, or a combination of these additives. The composition can thus comprise less than 10% by weight, preferably less than 5% by weight, and more preferably less than 1% by weight of additive (s) relative to the total weight of the composition.

The composition can be in the form of granules. The granules generally have a characteristic size of the order of 1 to 5 millimeters and can be obtained by compounding. The advantage of compounding is that it makes it possible to formulate a homogeneous composition comprising one or more PAEK (s) and / or to incorporate other constituents such as fillers and additives within the granules. The advantage of compounding is also that it makes it possible, according to certain embodiments, in particular for PAEKs having crystallization rates between T _g and Tm which are sufficiently low, to obtain a composition in amorphous form: this can be an advantage in the the case of compression molding since this can make it possible, according to certain embodiments, to reduce the duration of preparation of the composition in the molten state in the mold (as well as the energy expenditure for melting the composition).

The composition can also be in the form of a powder. A powder can be obtained by methods known per se, such as spray drying (spraydrying), grinding under cryogenic conditions or at room temperature, or else melt-spraying. In some embodiments, a pure PAEK powder, for example a pure PEKK powder, can be obtained by grinding scales (in English "flake"), that is to say of raw material, with irregular shapes. , of characteristic size of the order of a millimeter, and of generally fairly low density. The grinding can be carried out at a temperature between 0 ° C and 50 ° C as described in EP2776224. The powder can then undergo a densification step, as described in EP3215331. This makes it possible to incorporate a minimum volume of air in the cavity during filling, the air then having to advantageously be eliminated during a period of homogenization of the melt in the cavity.

The pure PAEK powder can be mixed "dry" (in English "dry blend") with other constituents such as other thermoplastic polymer (s) or such fillers and additives.

In other embodiments, a powder of PAEK (s) comprising at least fillers can be obtained by grinding granules.

The powder may have a distribution of particle diameters with a D50 less than or equal to 500 microns, preferably less than or equal to 300 microns, more preferably less than or equal to 100 microns, and extremely preferably of around 50 microns. The term “D50” is understood to mean the value of the diameter of the powder particles so that the cumulative function of distribution of the diameters of the particles, weighted by the volume, is equal to 50%. “D50” is measured by laser diffraction according to the ISO 13320: 2009 standard, for example on a Malvern Mastersizer 2000® diffractometer.

Compression shaping process

The manufacturing process according to the invention is a compression forming process. It allows to obtain articles of high thickness.

The method includes providing a semi-crystalline or crystallizable composition, as described above. The composition can in particular be in the form of granules or in the form of powder.

The method also includes providing a compression shaping means. This shaping means comprises a mold and a compression means. The molds used for shaping by compression are well known to those skilled in the art. They can in particular be of the positive, semi-positive or even flash type.

They include at least one cavity and at least one removable wall capable of closing said at least one cavity. When the mold is closed, a seal can be placed between the cavity and the removable wall so as to ensure the tightness of the closed mold. An opening can also be made in the mold to allow extrusion or injection of the composition in the molten state (see embodiment 2). The mold must be made of materials resistant to high temperatures, temperature variations, corrosion and high pressures. To facilitate mold release, a mold release agent can be applied to the internal walls of the mold.

The mold compression means exert pressure on at least the removable wall of the mold. The compression means may be a press, in particular a press of the hydraulic type, or in a more restricted use of the pneumatic type.

The mold and / or the compression means can be heated by an electrical system (reel, cartridge, tape, etc.), a vapor circulation system, an oil circulation system, etc.

A first compression shaping means 1 is shown in a simplified manner in FIG. 1.

11 comprises a mold 10, consisting of a first wall 11 of negative shape (open cavity) and of a second removable wall 12 of positive shape. The first wall 11 of the mold and the second wall 12 of the mold can be joined so as to form a closed cavity 13. The first wall 11 and the second wall

12 are mounted respectively on an upper plate 21 and a lower plate 22 of a press 20, the first and second plates being able to be heated. In addition, the first wall 11 of the mold 10 can optionally have heating means laterally (not shown).

A second compression shaping means 2 is shown in a simplified manner in Figure 2.

It comprises a mold 30 consisting of a ring 31 and two pistons 32. The ring 31 comprises two openings which can be closed by the pistons 32, so as to form a closed cavity 35. The ring 31 and / or the pistons 32 may have heating means (not shown).

Embodiment 1: compression molding

According to a first embodiment, the method is a method of compression molding a composition in the form of granules or in the form of powder. The composition is introduced into an open mold so as to fill the cavity to a predetermined level during a mold filling step.

The composition can optionally be preheated during a preheating step. The composition can in particular be preheated to a temperature close to its T _g , for example a temperature of 150 ° C.

The preheating step can in particular make it possible to remove all traces of water in the composition. According to some embodiments, the composition can be preheated under reduced pressure, that is to say at a pressure of less than 1 bar.

The preheating can be carried out before the mold filling step, for example in an air oven, or under infrared radiation and / or on a heated plate. In this case, once the preheating step is complete, the preheated powder is advantageously transferred rapidly into the mold brought to a temperature substantially equal to the preheating temperature. This allows the composition to reach a homogeneous temperature To more quickly once the mold is heated in order to reach a set point temperature To.

Alternatively, the preheating step can be carried out during and / or after the mold filling step.

After the open mold has been filled to the desired level, it can be closed. Pressure can optionally be exerted on the powder / granules in the mold so as to effect a settlement. Small amounts of powders / granules can then be added successively into the cavity, so as to fill the cavity to the desired level, the whole being compacted again by the application of pressure.

The closed mold, possibly preheated, filled with the composition, optionally packed, is then brought to a temperature To, with To³ (T _m +10) ° C, in order to melt all of the powder or (anules. During this step a low pressure can be maintained on the mold, for example a pressure of the order of 20 bars.

According to some embodiments, To ³ (T _m +20) ° C, or To ³ (T _m +30) ° C. In order to limit the thermo-oxidation, we generally have: To <(T _m +40) ° C.

Once the temperature To has been reached, a temperature plateau at To can be implemented for a variable homogenization period. The homogenization time allows the composition in the molten state to be sufficiently homogeneous: total melting of the composition, sufficiently homogeneous temperature between the core and the parts in contact with the mold, elimination of any air present in the powder or the pellets initially supplied.

The homogenization time can in particular be: 1 minute to 10 hours, preferably 1 hour to 5 hours. The homogenization time of granules will typically be longer than that of powder, in particular fine powders (Dso = 50 microns) and / or densified powders.

The mold comprising the composition in the molten state, preferably homogenized, is then compressed and cooled simultaneously during a compression and cooling step.

The pressure applied to the mold is implemented using the mold compression means. Preferably, the pressure has a value ranging from: 10 to 300 bars. The pressure may in particular have a value ranging from 10 to 50 bars, or ranging from 50 bars to 100 bars, or ranging from 100 bars to 150 bars, or ranging from 150 bars to 200 bars, or ranging from 200 bars to 250 bars, or ranging from 250 bars to 300 bars.

The applied pressure can be constant throughout substantially the entire compression and cooling step. The pressure applied can in particular be constant for at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or 100% of the total duration of the compression step. and cooling. The applied pressure is advantageously constant throughout the “compression and cooling” step. Alternatively, the pressure applied can be variable during the compression and cooling step. The cooling applied in the compression and cooling step can be implemented by a calorific fluid in contact with the mold and / or by blowing air on the mold.

The mold is cooled from temperature To to a final temperature Tt less than or equal to (T _g +30) ° C. The mold can in particular be cooled to a temperature less than or equal to (T _g +20) ° C, or to a temperature less than or equal to (T _g +10) ° C, or to a temperature less than or equal to at T _g , or up to a temperature less than or equal to (T _g -10) ° C, or again up to a temperature close to ambient temperature.

The cooling is preferably carried out at an average speed of 0.25 ° C / min at 2.5 ° C / min, preferentially at an average speed of 0.5 ° C / min at 2 ° C / min between To and Tt . The thicker the article being molded, the slower the cooling rate will need to be since heat transfer to the article core occurs only by thermal convection.

The cooling rate can be constant throughout substantially the entire "compress and cool" stage. The cooling rate can in particular be constant for at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or 100% of the total duration of the step of "Compression and cooling". The cooling is advantageously carried out at a constant speed of 0.25 ° C / min at 2.5 ° C / min, preferably at a speed of 0.5 ° C / min at 2 ° Omin between To and Tt during substantially all of the compression and cooling step.

Alternatively the cooling rate can be variable during the compression and cooling stage. A cooling profile made up of temperature ramps as a function of time and of temperature stages can in particular be envisaged.

At the end of the "compress and cool" step, the pressure on the mold is released. An article shaped by molding is thus obtained within the cavity.

The shaped article is finally demolded at a mold temperature less than or equal to Tt. It can in particular be demolded at the temperature Tt, or at a mold temperature between Tt and room temperature, or the where appropriate at a mold temperature equal to approximately room temperature.

The demolded article can then optionally be annealed in order to eliminate any residual mechanical stress and / or in order to increase its crystallinity. The annealing step comprises: heating at a speed ranging from 0.1 ° C to 20 ° C / hour to a temperature greater than or equal to the T _g of the article, a more or less long stage (in particular depending on the thickness of the article) at this plateau temperature, followed by cooling at a rate ranging from 0.1 ° C to 20 ° C / hour. The plateau temperature can for example be of the order of (T _g + Tm) / 2.

Embodiment 2: shaping by extrusion-compression (or injection-compression)

The step of preparing the composition in the molten state in the mold can be carried out by extrusion or by injection.

In this embodiment, the composition is extruded (or injected) in the molten state into the mold cavity, the mold having an initial temperature To £ T _m . For a temperature To not too lower Tm, it is thus possible to keep a composition in the molten (or supercooled) state throughout the duration of the filling of the cavity. Once the cavity is completely filled with the composition in the molten state, a period of homogenization of the composition in the molten state can be implemented, the mold being maintained at the temperature To. this embodiment is generally much less than that of embodiment 1.

In order to allow maintenance in the substantially molten state, without substantially crystallizing, throughout the duration of the filling and / or homogenization step, the composition used advantageously has a sufficiently high isothermal half-crystallization time at To. with regard to the aforementioned periods.

According to some embodiments, To £ (T _m -5) ° C, or To <(T _m -10) ° C, or To £ (T _m - 20) ° C, or To £ (Tm-25) ° C, To £ (Tm-30) ° C, or To <(T _m -35) ° C, or also To £ (T _m - 40) ° C.

The following steps are the same as those described in the powder / granule compression molding embodiment. The mold comprising the composition in the molten state, preferably homogenized, is then compressed and cooled during a compression and cooling step, and the like.

The embodiment by shaping by extrusion-compression has the advantage that the mold temperature Toest generally lower than for the embodiment by shaping by compression of powder or granules, which makes it possible to further limit the phenomena. thermal oxidation and further reduce the duration of the compression and cooling step.

Item

The article obtained by the process according to the invention is generally simple in shape. It can be in the form of a plate, in the form of a parallelepiped (in particular a cube or a block) or in the form of a cylinder ("roller") and be used as a semi-finished product.

Given the advantages of the method according to the invention (in particular lower maximum temperature reached and speed of the compression-cooling step), relatively large thicknesses can be reasonably envisaged. The article may in particular have a thickness greater than or equal to 5 mm, or greater than or equal to 10 mm, or greater than or equal to 20 mm, or greater than or equal to 30 mm, or greater than or equal to 40 mm, or greater or equal to 50 mm, or greater than or equal to 60 mm, or greater than or equal to 75 mm.

The compression extrusion or injection-compression process (see embodiment 2) makes it possible in particular to obtain thick articles while having a reasonable duration of the compression and cooling step.

The article, which has optionally undergone an annealing step, advantageously has an enthalpy of fusion greater than or equal to 25 J / g (PAEK), preferably greater than or equal to 30 J / g (PAEK), and more preferably greater than or equal to 35 J / g (PAEK), as measured on first heating by DSC with a ramp of 20 ° C / min. Examples

Example 1

Pure poly-ether-ketone-ketone powder, having a T / l molar ratio of 60:40 and a D50 of 300 microns, was used to make a roller (flat cylinder) 240 mm in diameter and 25 mm thickness, by a powder compression molding process, as described in Embodiment 1.

The precise conditions used are detailed below.

The powder was introduced into the open mold and then packed.

It was then dried by heating the mold at 120 ° C for 8 hours at 120 ° C.

The temperature of the mold was then gradually increased, over a period of 3 hours 30 minutes, from the temperature of 120 ° C. until reaching a temperature To of 330 ° C.

Once the temperature To was reached, a temperature plateau at To lasting 4 hours 30 minutes was implemented.

The compression and cooling step was then carried out at a constant cooling rate under a constant pressure of 25 bar. It allowed the mold to be cooled from its initial temperature To to a final temperature Tt of 180 ° C for a period of 2h05.

The article was removed from the mold at Tt and then allowed to cool to room temperature (25 ° C).

The item was eventually annealed in an oven. The annealing was carried out by heating according to a ramp of 5 ° C / hour from a temperature of 25 ° C until reaching a plateau temperature of 250 ° C, maintaining the plateau temperature at 250 ° C for a few hours, then cooling according to a ramp of 3 ° C / hour until reaching a temperature of 25 ° C.

Example 2

Poly ether ketone ketone pure, having a mole ratio T / l of 60: 40 and a melt flow rate of 16 cm ^3/10 min (at 380 ° C under a load of 5 kg) was utlise for fabricate a plate with a length of 600 mm, a width of 240 mm and a thickness of 25 mm by an extrusion-compression process, as described in embodiment 2.

The composition was extruded at a temperature of 340 ° C in a mold maintained at a temperature To of 285 ° C. The filling of the mold with the extruded composition took about 10 minutes.

A temperature plateau at To for a duration of 25 minutes was then implemented.

The compression and cooling step was carried out at a constant cooling rate under a constant pressure of 250 bar. It allowed the mold to be cooled from its initial temperature To to a final temperature Tt of 180 ° C for a period of 2h05.

It was then annealed analogously to the article according to Example 1.

The article, before and after annealing, is ivory in color, characteristic of crystallized PEKKs. It has a beautiful visual appearance (homogeneous color).

Example 3

Poly ether ketone ketone pure having a ratio T / L of 70: 30 and a melt index of 8 cm ^3/10 min (at 380 ° C under a load of 5 kg) was utlise to manufacture a plate of length 600 mm, width 240 mm and thickness 25 mm by an extrusion-compression process, as described in embodiment 2.

The composition was extruded at a temperature of 385 ° C in a mold maintained at a temperature To of 325 ° C. The filling of the mold with the extruded composition took about 10 minutes.

A temperature plateau at To for a duration of 25 minutes was then implemented.

The compression and cooling step was carried out at a constant cooling rate under a constant pressure of 250 bars. It allowed the mold to be cooled from its initial temperature To to a final temperature Tt of 180 ° C. for a period of 2:05. The article was removed from the mold at temperature Tt and then left to cool to room temperature (25 ° C.).

It was then annealed analogously to the article according to Example 1.

Characterization of the articles obtained

The articles according to Examples 2 and 3 have been characterized.

Samples of "core" (that is, far enough from the outer edges of the plate so as to avoid any edge effects) of plaque were taken. Their enthalpy of fusion DH, expressed in J / g, was determined by DSC, on first heating with a heating ramp of 20 ° C./min.

"1 A" type specimens, according to the ISO 527-2: 2012 standard, were machined in the heart of the plates, then mechanically tested in tension at 23 ° C at a crosshead speed of 50 mm / min. Five specimens were tested to determine the mean values of:

- modulus of elasticity, "E", expressed in GPa;

- yield stress, "Oseuii", expressed in MPa;

- deformation at the yield point, "Eseuii", expressed in%; and,

- nominal strain at break, "nominal break", expressed in%.

The results of these characterizations are collated in Table 1 below (mechanical properties averaged over 5 samples):

[Table 1]

Claims

1. A method of manufacturing an article by compression shaping comprising:

- providing a semi-crystalline or crystallizable composition comprising at least one poly-aryl-ether-ketone, said composition having a glass transition temperature T _g and a melting temperature T _m ;

- the provision of a compression shaping means comprising: a mold (1, 2) and a means for compressing the mold, the mold having at least one cavity (13, 35) and at least one removable wall (20 , 32) adapted to close said at least one cavity, the compression means being able to exert pressure on at least said removable wall;

- compressing and cooling the composition in the molten state in said at least one cavity, the mold being cooled from temperature To to a final temperature Tt less than or equal to (T _g + 30) ° C, to form a shaped article by compression; and,

2. The method of claim 1, wherein the composition has a glass transition temperature T _g strictly greater than 145 ° C, and preferably greater than or equal to 150 ° C.

3. A method according to any one of claims 1 and 2, wherein the melt index of the composition has a value ranging from 1 to 100 cm ^3/10 min, and preferably yardstick value ranging from 2 to 60 cm ^3/10 min, To380 ° C and under a load of 5 kg.

4. A method according to any one of claims 1 to 3, wherein the cooling in the step of "compressing and cooling" is carried out at an average rate of: 0.25 ° C / min to 2.5 ° C / min, and preferably at an average speed of: 0.5 ° C / min at 2 ° C / min ente Toet Tt.

5. Method according to any one of claims 1 to 4, wherein the composition has an isothermal half-crystallization time at a temperature of (Tm-20) ° C greater than or equal to 5 minutes, preferably greater than or equal to 10. minutes, and more preferably greater than or equal to 15 minutes.

6. Method according to any one of claims 1 to 5, wherein said at least one poly-aryl-ether-ketone of the composition represents at least 60%, or at least 70%, or at least 80%, or at least. at least 85%, or at least 90%, or at least 92.5%, or at least 95%, or at least 97.5%, or at least 98%, or at least 98.5%, or at least 99% or at least 99.5% , or 100% by weight, relative to the total weight of the composition.

7. A method according to any one of claims 1 to 6, wherein said at least one poly-aryl-ether-ketone is a poly-ether-ketone-ketone.

8. The method of claim 7, wherein said poly-ether-ketone-ketone is a copolymer consisting essentially of, preferably consisting of: a terephthalic unit and an isophthalic unit, the terephthalic unit having the formula:

[Chem 14] the isophthalic unit having the formula: [Chem 15] the molar percentage of terephthalic unit relative to the sum of the terephthalic and isophthalic units being from 45% to 75%, preferably from 48% to 72%, more preferably from 54% to 66%, and extremely preferably from 58 % to 64%.

9. A method according to any one of claims 1 to 6, wherein said at least one poly-aryl-ether-ketone is a copolymer comprising a unit of the formula:

[Chem 16] and a unit of formula: [Chem 17] the molar percentage in unit (III) relative to the sum of units (III) and (IV) being from: 55% to 95%, and preferably from: 60% to 85%.

10. A method according to any one of claims 1 to 6, wherein said at least one poly-aryl-ether-ketone is a copolymer comprising a unit of the formula:

[Chem 18] and a unit of formula: [Chem 19] the molar percentage in unit (III) relative to the sum of units (III) and (V) being from 0 to 95%, preferably from 40% to 95%, and more preferably from 70% to 95%.

11. A method according to any one of claims 1 to 10, wherein the composition is provided in the form of granules.

12. Method according to any one of claims 1 to 10, wherein the composition is provided in powder form, preferably in powder form having a distribution of particle diameters having a D50 less than or equal to 500 microns, preferably less than or equal to or less than 500 microns. equal to 300 microns, more preferably less than or equal to 100 microns, and extremely preferably about 50 microns.

13. The method of claim 11 or 12, wherein the preparation of the melt composition comprises:

filling the cavity with said powder, or said granules, and optionally compacting said powder, or respectively said granules, in the cavity to obtain a cavity filled with powder, or respectively filled with said granules; and, - heating the mold filled with powder, or respectively granules, to temperature To, with To³ (Tm + 10) ° C, in order to melt all of the powder or granules;

14. A method according to any one of claims 1 to 10, wherein, the preparation of the composition in the molten state comprises transferring the already molten composition into the cavity, the mold being maintained at the temperature To, with To £ T _m , to obtain a mold filled with the composition in the state of molten.

15. Article obtained by the process according to any one of claims 1 to 14.

16. Article according to claim 15 having a thickness greater than or equal to 75 mm.

17. Article according to any one of claims 15 and 16, having an enthalpy of fusion greater than or equal to 25 J / g (PAEK), preferably greater than or equal to 30 J / g (PAEK), and more preferably greater than or equal to 35 J / g (PAEK), as measured by DSC on first heating with a heating ramp of 20 ° C / min.