WO2024017899A1 - Thermoplastic composite materials - Google Patents

Abstract

A collection of particles made of a thermoplastic composition comprising at least one semi-aromatic polyamide are provided which have a median particle size on a volume basis, D(v, 0.5), from 0.1 to 50.0 μm and an asymmetric particle size distribution. The collection of particles are suitable for the preparation of composite materials comprising continuous fibers by a slurry impregnation process.

Description

THERMOPLASTIC COMPOSITE MATERIALS

CROSS REFERENCE TO RELATED APPLICATIONS

This applications claims priority to US provisional patent application number 63/391 ,349, filed on July 22, 2022, and to European patent application number 22191834.5, filed on August 24, 2022, both of which are incorporated herein by reference in their entirety for all purposes.

Technical Field

[0001] The invention relates to thermoplastic composite tapes comprising semiaromatic polyamides and continuous fibers as well as to the semi-aromatic polyamide particles and compositions for making said tapes.

Background Art

[0002] Composite materials comprising structural reinforcing fibers embedded in a polymeric matrix are employed in a wide variety of applications. For example, composite materials comprising continuous fibers have been used to form fiber reinforced composite tapes, ribbons, rods, prepregs, laminates, and profiles useful as lightweight structural reinforced components in a number of applications. Composite materials comprising a thermoplastic polymer matrix are known to offer a number of benefits over thermosetting based materials. For example, thermoplastic tapes or prepregs can be more rapidly fabricated into articles. Another advantage is that thermoplastic articles may be recycled.

[0003] Thermoplastic composite materials comprising continuous fibers can be produced via impregnation of continuous fibers, typically carbon or glass fibers, generally using one of two methods: melt impregnation or slurry impregnation.

[0004] Melt impregnation employs a traditional melt processing equipment in combination with a specialized die, which serves to combine the molten polymer with the fiber and ensure homogeneous distribution of polymer within the spread fibers. This method suffers from the drawback that it is difficult to homogeneously heat a molten mixture of thermoplastic polymers in a die and at the die outlet to the core of the material, which alters the impregnation quality. In addition, the difference in existing temperature between the fibers and a molten mixture of polymers at the level of the impregnation die also alters the quality and homogeneity of the impregnation. Furthermore, this mode of impregnation from the melt does not make it possible to obtain high fiber contents or high production speeds due to the high viscosity of thermoplastic resins, especially when they have high glass transition temperatures, which is necessary for obtaining high performance composite materials.

[0005] Slurry impregnation is different in that, while a die is sometimes still employed, the impregnation step occurs by the passage of the continuous fibers through an actively mixed, aqueous, colloidal suspension containing the polymer. This suspension typically contains both polymer particles and water, while the active mixing prevents settling of the polymer particles.

[0006] For instance, US4292105 discloses a method of impregnating a fibrous textile material with a plastic resin which comprises forming a dispersion of a powdered plastic resin in water in the presence of a water-soluble thickener; applying the dispersion to a fibrous textile material to distribute the resin over the fibers; drying the impregnated fibrous textile material to remove the water present; and heating the dried material to cause the resin to fuse and form a matrix for the fibers. US4292105 acknowledges that penetration of the powdered plastic resin between the filaments of the fibrous material may be facilitated by using particles having sizes below 50 microns and in particular particles having diameters approaching the diameter of the filaments of the fibrous material. However, working examples in US4292105 only disclose the use of plastic resin particles having sizes such that they pass through 177 or 250 microns sieves. US4292105 does not provide suitable methods, besides sieving, for preparing said particles. Additionally US4292105 does not acknowledge the importance of using particles having a uniform distribution of particle size and/or shape in the process for the preparation of composite materials via a slurry impregnation process, and consequently does not disclose a method for the preparation of said particles starting from a wide range of polymers.

[0007] Milling or grinding might provide access to polymer particles having suitable sizes. However, milled particles tend to have irregular and oftentimes jagged edge shapes and wide particle size distributions. Irregular particulate shapes may result in poor powder flow performance during a tape impregnation process. In addition, powder particles having shape irregularity may afford poor packing efficiency following deposition and consolidation, thereby resulting in extensive void formation in the final composite tape due to the powder particles not packing closely together during deposition.

[0008] There are added complications for producing powders from polymers of low crystallinity, low glass transition temperature, and/or high toughness. In other words, these attributes impede the powder production process. For example, high polymer ductility during the milling process results in particle shape change (i.e. flattening) rather than size reduction. Even when using a cryogenic milling technique, which is a method for bringing the milling temperature below the glass transition temperature of the polymer in order to alleviate the issue of high polymer ductility, it is still difficult to achieve small particle size distributions.

[0009] Thus, the need still exists for providing polymer particles to be used in aqueous slurries for the preparation of composite materials via an impregnation process and which have an average particle size in the range of 0.1 to 50.0 microns and regular shape. In particular, the need exists to provide said particles made of polymers having low glass transition temperatures and/or high toughness which make accessing small particle diameters by mechanical grinding difficult because of the tendency of the particles to stick to the grinding apparatus.

[0010] Semi-aromatic polyamides are among polymers which could ideally provide suitable polymeric matrices for composite materials because of their outstanding mechanical properties but which suffer from the above detailed limitations, namely the difficulty to be obtained in the form of powders comprising particles having 0.1 to 50.0 microns average size as well as regular shape.

[0011] Additionally, semi-aromatic polyamide polymers that are partially or completely derived from renewable resources and meet the aforementioned requirements are even more desirable, as they provide an environmentally friendly solution. Summary of invention

[0012] The inventors, with an aim to provide access to processes for the preparation of composite materials comprising semi-aromatic polyamides using a slurry impregnation process, have discovered that semi-aromatic polyamide powders comprising particles having an average particle size, particle size distribution and shape which are suitably designed for the slurry impregnation process can be prepared using a melt extrusion process. In said process a thermoplastic polymer and a material that is immiscible with the thermoplastic polymer but generally soluble in a given solvent are mixed, typically in an extruder, at a temperature greater than a melting point or softening temperature of the thermoplastic polymer and at a shear rate sufficiently high to disperse the thermoplastic polymer in the immiscible material; the molten mixture is then cooled to below the melting point or softening temperature of the thermoplastic polymer to form solidified particles comprising thermoplastic polymer particles; which are then separated from the immiscible material, typically by dissolving the immiscible material in an appropriate solvent.

Description of invention

[0013] In the present application:

- any description, even though described in relation to a specific embodiment, is applicable to and interchangeable with other embodiments of the present disclosure;

- where an element or component is said to be included in and/or selected from a list of recited elements or components, it should be understood that in related embodiments explicitly contemplated here, the element or component can also be any one of the individual recited elements or components, or can also be selected from a group consisting of any two or more of the explicitly listed elements or components; any element or component recited in a list of elements or components may be omitted from such list;

- any recitation herein of numerical ranges by endpoints includes all numbers subsumed within the recited ranges as well as the endpoints of the range and equivalents; - the terms “a”, “an”, or “the” means “one or more” or “at least one” and may be used interchangeably, unless otherwise stated; and

- the term “and/or” used in a phrase in the form of “A and/or B” means A alone, B alone, or A and B together.

[0014] A first object of the invention is a collection of particles wherein the particles consist of a thermoplastic composition comprising at least one semiaromatic polyamide; and wherein the particles have a median particle size on a volume basis, D(v, 0.5), from 0.1 to 50.0 μm and a particle size distribution such that the following relationship (I) is met:

in which D(v, 0.9) is the size of particle below which lies 90% of the sample; D(v, 0.5) is the size of particle at which 50% of the sample is smaller and 50% is larger; D(v, 0.1) is the size of particle below which lies 10% of the sample.

[0015] The thermoplastic composition

[0016] The thermoplastic composition comprises at least one semi-aromatic polyamide. The expression semi-aromatic polyamide refers to a polyamide comprising recurring units deriving from at least one aromatic monomer and at least one aliphatic monomer. The aromatic monomer may be a diamine, a diacid or an aminoacid.

[0017] In an embodiment, the semi-aromatic polyamide may comprise recurring units deriving from an aromatic diamine.

[0018] The semi-aromatic polyamide may comprise at least 50 mol%, typically at least 70 mol% of recurring units deriving from the aromatic diamine with respect to the total amount of diamine units in the polyamide.

[0019] Preferably, the semi-aromatic polyamide comprises recurring units deriving from an aromatic diamine having 6 to 18 carbon atoms.

[0020] Examples of suitable C6-C18 aromatic diamines include, but are not limited to, m-phenylene diamine (MPD), p-phenylene diamine (PPD), 3,4’- diaminodiphenyl ether (3,4’ ODA), 4,4’-diaminodiphenyl ether (4,4’-ODA), p-xylylene diamine (PXD) and m-xylylenediamine (MXD).

[0021] Notable non-limiting examples of suitable polyamides comprising aromatic diamines are for instance polyamides comprising recurring units of formula MXDZ in which Z represents units deriving from a linear or branched, aliphatic or cyclo-aliphatic diacid having z carbon atoms, wherein z is an integer equal to or greater than 6 and MXD is m-xylylenediamine. Z is preferably selected from the aliphatic diacids having 6 to 16 carbon atoms. Notable non limiting examples are adipic acid, sebacic acid or dodecanedioic acid. More preferably, Z is adipic acid.

[0022] In some embodiments, the semi-aromatic polyamide may additionally comprise recurring units of formula PXDZ wherein PXD represents units deriving from p-xylylene diamine and Z is as defined above.

[0023] In certain embodiments, the semi-aromatic polyamide is a polyamide of formula A/MXDZ in which A is a recurring unit derived from at least one of the following: an amino acid, that is a molecule containing a primary carboxylic acid and a primary amine, a lactam or a unit with the formula (Ca diamine). (Cb diacid), where “a” represents the number of carbon atoms of the diamine and “b” represents the number of carbon atoms of the diacid, and wherein “a” and “b” independently of each other are integers between 4 and 36, advantageously between 6 and 18. The component (Ca diamine) is preferably selected from the group consisting of the linear or branched aliphatic diamines, the cycloaliphatic diamines and the alkylaromatic diamines. Examples are for instance, hexamethylenediamine, decanediamine, dodecanediamine and MXD.

[0024] The component (Cb diacid) is preferably selected from the group consisting of the linear or branched aliphatic diacids, the cycloaliphatic diacids and the aromatic diacids. Examples are for instance, adipic acid, sebacic acid or dodecanedioic acid or 3-(aminomethyl)benzoic acid (3-AMBa).

[0025] In an advantageous embodiment, the units A or Z can be derived from renewable materials. Non limiting examples of suitable polyamides of this type are: PA MXD6, PA MXD10.

[0026] In another embodiment, the semi-aromatic polyamide comprises recurring units deriving from an aromatic diacid.

[0027] In a preferred embodiment, the semi-aromatic polyamide comprises recurring units of formula XT, in which X represents units deriving from a linear or branched, aliphatic or cyclo-aliphatic diamine having x carbon atoms, wherein x is an integer equal to or greater than 6 and T represents units deriving from terephthalic acid.

[0028] The semi-aromatic polyamide comprises at least 50 mol%, typically at least 70 mol% of recurring units of formula XT, even at least 90 mol% of recurring units of formula XT.

[0029] The semi-aromatic polyamide may comprise more than one recurring unit of formula XT, wherein each unit X derives from a different diamine. Alternatively the semi-aromatic polyamide may comprise, in addition to recurring units of formula XT, recurring units of formula X’T, in which X’ in represents units deriving from a linear or branched, aliphatic or cycloaliphatic diamine having x’ carbon atoms, wherein x’ is an integer lower than 6.

[0030] In some embodiments, the semi-aromatic polyamide may additionally comprise recurring units of formula XI, wherein I represents units deriving from isophthalic acid and X is as defined above.

[0031] The units X in formula XT, or units XI when present, derive from a linear or branched, aliphatic or cyclo-aliphatic diamine having x carbon atoms, x being greater than 6 and up to 36, advantageously between 8 and 18. Units X preferably derive from aliphatic diamines selected from the group consisting of 1 ,8-octanediamine, 1 ,9-nonanediamine, 2-methyl-1 ,8- octanediamine (Me8), 1 ,10-decanediamine, 1 ,12-dodecanediamine, 2,2,4- trimethyl- 1 ,6-hexanediamine, 2 ,4,4-trimethyl-1 ,6-hexanediamine, 5-methyl- 1 ,9-nonanediamine, 1 ,3-bis(aminomethyl)cyclohexane, 1 ,4- bis(aminomethyl)cyclohexane, isophoronediamine and mixtures thereof. In a preferred embodiment of the invention, unit X derives from the group of aliphatic diamines consisting of 1 ,8-octanediamine, 1 ,9-nonanediamine, 2- methyl-1 ,8-octanediamine, 1 ,10-decanediamine, 1 ,12-dodecanediamine and mixtures thereof. More preferably unit X derives from the group of aliphatic diamines consisting of 1 ,9-nonanediamine, 2-methyl-1 ,8- octanediamine, 1 ,10-decanediamine, 1 ,12-dodecanediamine and mixtures thereof.

[0032] In certain embodiments, the aliphatic diamine can be derived from renewable materials. Notable non-limiting examples of such diamines are for instance 1 , 10-decanediamine and 1 , 12-dodecanediamine, which can be derived from castor oil.

[0033] Notable non-limiting examples of suitable polyamides comprising only recurring units of formula XT or XT/X’T are PA 6T, PA 8T, PA Me8T, PA 9T, PA Me8T/9T, PA 10T, PA 11T, PA 12T, PA 6T/9T, PA 9T/10T, PA 9T/ 11T, PA 9T/12T, PA 6T/10T, PA 6T/11T, PA 6T/12T, PA 10T/11 T, PA 10T/12T,

PA 11T/12T.

[0034] In certain embodiments, the semi-aromatic polyamide is a co-polyamide of formula Y/XT, wherein XT is as defined above and Y is a recurring unit derived from at least one of the following: an amino acid, that is a molecule containing a primary carboxylic acid and a primary amine, a lactam or a unit with the formula (Cn diamine) (Cm diacid), where “n” represents the number of carbon atoms of the diamine and “m” represents the number of carbon atoms of the diacid, and wherein “n” and “m” independently of each other are integers between 4 and 36, advantageously between 6 and 18. The component (Cn diamine) is preferably selected from the group consisting of the linear or branched aliphatic diamines, the cycloaliphatic diamines and the alkylaromatic diamines. The component (Cm diacid) is preferably selected from the group consisting of the linear or branched aliphatic diacids, the cycloaliphatic diacids and the aromatic diacids.

[0035] In an advantageous embodiment, the units Y in formula Y/XT can be derived from renewable materials. Notable non-limiting examples of diacids or aminoacides derived from renewable sources are for instance sebacic acid or 3-(aminomethyl)benzoic acid (3-AMBa), which can be derived from furfural.

[0036] Notable non-limiting examples of suitable co-polyamides of formula Y/XT are polyamides of formula Y/6T, Y/9T, Y/10T or Y/11 T, Y being as defined above. Suitable co-polyamides are in particular polyamides from: PA 10/6T, 6 PA 10/9T, PA 10/10T, PA 10/11T, PA 10/12T, PA 11/6T, PA 11 /9T, PA 11 /10T, PA 11 /11 T, PA 11 /12T, PA 12/6T, PA 12/9T, PA 12/10T, PA 12/11T, PA 12/12T, PA 610/6T, PA 612/6T, PA 910/6T, PA 912/6T, PA 1010/6T, PA 1012/6T, PA 610/9T, PA 612/9T, PA 910/9T, PA 912/9T, PA 1010/9T, PA 1012/9T, PA 610/10T, PA 612/ 10T, PA 910/10T, PA 912/10T, PA 1010/10T, PA 1012/10T, PA 610/12T, PA 612/12T, PA 910/12T, PA 912/12T, PA 1010/12T, PA 11/6T/9T, PA 11/6T/10T, PA 11/6T/11T, PA 11/6T/12T, PA 11/9T/10T, PA 11/9T/11T, PA 11/9T/12T, PA 11/10T/11T, PA 11/10T/12T, PA 11/11 T/12T, PA 12/6T/10T, PA 12/6T/11T, PA 12/6T/12T, 12/9.T/10.T, PA 12/9T/11T, PA 12/9T/12T, PA 12/10T/11T, PA 12/10T/12T, PA 12/11T/12T, PA MXDT/10T, PA MPMDT/10T, PA BACT/10T, PA BACT/6T, PA BACT/10T/6T.

[0037] The thermoplastic composition may consist of the semi-aromatic polyamide. [0038] Alternatively, the thermoplastic composition may comprise one or more additives. Examples of suitable additives include, but are not limited to, fillers, strengtheners, pigments, pH regulators, lubricants, heat stabilizers, light stabilizers, antioxidants, processing aids and combinations thereof. Examples of fillers include, but are not limited to, glass fibers, glass particles, mineral fibers, carbon fiber, oxide particles (e.g., titanium dioxide, silica, zinc oxide, cerium oxide and zirconium dioxide), metal particles (e.g., aluminum powder), talc, wollastonite, calcium carbonate, mica and any combination thereof. Examples of pigments include, but are not limited to, organic pigments, inorganic pigments, carbon black, and any combination thereof.

[0039] The polymer composition may further comprise flame retardants such as halogen and halogen free flame retardants.

[0040] The additive may be present in the thermoplastic composition in an amount of 0.1 wt% to about 40.0 wt%, even 1.0 wt% to 35.0 wt%, or 5.0 wt% to 30.0 wt% percent with respect to the total weight of the thermoplastic composition.

[0041] In certain embodiments, the thermoplastic composition may comprise one or more thermoplastic polymer different from the semi-aromatic polyamide. Examples of suitable polymers include, but are not limited to, impact modifiers. The polymer backbone of the impact modifier can be selected from elastomeric backbones comprising polyethylenes and copolymers thereof, e.g. ethylene-butene; ethylene-octene; polypropylenes and copolymers thereof; polybutenes; polyisoprenes; ethylene-propylene- rubbers (EPR); ethylene-propylene-diene monomer rubbers (EPDM); ethylene-acrylate rubbers; butadiene-acrylonitrile rubbers, ethylene-acrylic acid (EAA), ethylene-vinylacetate (EVA); acrylonitrile-butadiene-styrene rubbers (ABS), block copolymers styrene ethylene butadiene styrene (SEBS); block copolymers styrene butadiene styrene (SBS); core shell elastomers of methacrylate-butadiene-styrene (MBS) type, or mixture of one or more of the above.

[0042] When the impact modifier is functionalized, the functionalization of the backbone can result from the copolymerization of monomers which include the functionalization or from the grafting of the polymer backbone with a further component. Specific examples of functionalized impact modifiers are notably terpolymers of ethylene, acrylic ester and glycidyl methacrylate, copolymers of ethylene and butyl ester acrylate; copolymers of ethylene, butyl ester acrylate and glycidyl methacrylate; ethylene-maleic anhydride copolymers; EPR grafted with maleic anhydride; styrene copolymers grafted with maleic anhydride; SEBS copolymers grafted with maleic anhydride; styrene-acrylonitrile copolymers grafted with maleic anhydride; ABS copolymers grafted with maleic anhydride.

[0043] Functionalized polyolefin impact modifiers are available from commercial sources, including maleated polypropylenes and ethylene-propylene copolymers available as Exxelor® PO and maleic anhydride-functionalized ethylene-propylene copolymer rubber comprising about 0.6 weight percent pendant succinic anhydride groups, such as Exxelor® VA 1801 from the Exxon Mobil Chemical Company; acrylate-modified polyethylenes available as Surlyn®, such as Surlyn® 9920, acrylic or methacrylic acid-modified polyethylene from Dow Inc.; maleic anhydride-modified SEBS block copolymer, such as Kraton® FG1901X, a SEBS that has been grafted with about 2 wt. % maleic anhydride, available from Kraton Polymers; maleic anhydride-functionalized EPDM terpolymer rubber, such as Royaltuf® 498, a 1 % maleic anhydride functionalized EPDM, available from the SI Group.

[0044] Other desirable functionalized impact modifiers include, but are not limited to, ethylene-higher alpha-olefin polymers and ethylene-higher alpha-olefin- diene polymers grafted or copolymerized with reactive carboxylic acids or their derivatives such as, for example, acrylic acid, methacrylic acid, maleic anhydride or their esters. Suitable higher alpha-olefins include, but are not limited to, C3 to C8 alpha-olefins such as, for example, propylene, 1- butene, 1 -hexene and styrene. Alternatively, copolymers having structures comprising such units may also be obtained by hydrogenation of suitable homopolymers and copolymers of polymerized 1-3 diene monomers. For example, polybutadienes having varying levels of pendant vinyl units are readily obtained, and these may be hydrogenated to provide ethylenebutene copolymer structures. Similarly, hydrogenation of polyisoprenes may be employed to provide equivalent ethylene-isobutylene copolymers.

[0045] Among reactive impact modifiers mention may be made of a random terpolymer of ethylene, acrylic ester and glycidyl methacrylate which is commercially available from Arkema (Bristol, PA, USA) under the trade name Lotader® AX8900. Another example of the aforementioned reactive impact modifier is commercially available from Dow Inc. (Midland, Ml, USA) under the trade name Paraloid™ EXL 2314, which is a core-shell type acrylate based impact modifier comprised of a core primarily comprised of cross-linked poly(n-butyl acrylate) rubber and having a shell phase comprised primarily of a poly(methyl methacrylate)-poly(glycidyl methacrylate) copolymer.

[0046] The thermoplastic composition may comprise from 0.5 wt% to 25.0 wt% of the at least one impact modifier with respect to the total weight of the composition. The impact modifier can be at least 1 .0 wt%, at least 2.0 wt. % or at least 3.0 wt%, even at least 5.0 wt% of the total weight of the composition. The impact modifier typically is not more than 20.0 wt %, not more than 15.0 wt%, not more than 12.0 wt%, even not more than 10.0 wt%. Suitable ranges may be for instance from 0.5 to 15.0 wt%, even from 0.5 to 12.0 wt%, or even 2.0 to 10.0 wt%.

[0047] The particles

[0048] As used herein, the term “particle” refers to an individualized entity.

[0049] The particles have a median particle size on a volume basis, D(v, 0.5), from 0.1 to 50.0 μm and a particle size distribution such that the following relationship (I) is met:

[0050] In relationship (I) :

- D(v, 0.9) is the size of particle below which lies 90% of the sample; - D(v, 0.5) is the size of particle at which 50% of the sample is smaller and 50% is larger; and

- D(v, 0.1 ) is the size of particle below which lies 10% of the sample. [0051] As used herein, the particle size distribution refers to volume distribution, unless otherwise stated. Particle size distribution may be determined according to any method known in the art. In particular, particle size, as well as the particle size distribution was determined by laser diffraction on a suspension in isopropanol of the collection of the particles. A MicroTrac S3500 laser diffraction instrument can be used, according to the manufacturers’ instructions or known methods. The detailed method is disclosed in the Experimental Section.

[0052] The particles in the collection of the present invention have a median particle size D(v, 0.5) from 0.1 to 50.0 μm, typically from 1.0 to 50.0 μm. The median particle size D(v, 0.5) may conveniently be at least 1.5 μm, even at least 2.5 μm, still at least 5.0 μm. The average particle size D(v, 0.5) may conveniently be less than 50.0 μm, even less than 45.0 μm. In some embodiments the average particle size D(v, 0.5) is from 2.5 μm to 40.0 μm, preferably from 5.0 μm to 30.0 μm, or from 7.5 μm to 25.0 μm.

[0053] The particles may further have a particle size distribution such that D(v, 0.9) is 100.0 μm or less, typically 65.0 μm or less, even 50.0 μm or less.

[0054] Additionally, the particles may further have a particle size distribution such that D(v, 0.1) is at least 1.0 μm, typically at least 2.5 μm, more typically at least 5.0 μm.

[0055] Any combination of D(v, 0.1), D(v, 0.5), and D(v, 0.9) ranges described above is contemplated by the present disclosure.

[0056] The particles of the present invention have a particle size distribution which is asymmetric with respect to the value of D(v, 0.5) as shown by relationship (I) :

[0057] In certain embodiments the particle size distribution is such that relationship (la) is met:

even:

[0058] The particle size distribution may be such that the following relationship (II) is also met:

[0059] Without being bound by theory it is believed that a particle size distribution skewed towards the larger particle sizes is advantageous in the preparation of continuous fiber composite materials by means of a slurry impregnation process as it reduces the risk of frothing which may be caused by the particles having smaller diameter when forming the slurry.

[0060] Advantageously the particles are characterized by the following combination of properties:

D(v, 0.5) from 0.1 to 50.0 μm, typically from 1.0 to 50.0 μm, from 2.5 μm to 40.0 μm, preferably from 5.0 μm to 30.0 μm, even from 7.5 μm to 25.0 μm; and

D(v, 0.9) is 100.0 μm or less, typically 65.0 μm or less, even 50.0 μm or less; and/or

- D(v, 0.1) is at least 1.0 μm, typically at least 2.5 μm, more typically at least 5.0 μm.

[0061] The particles preferably have a regular shape, that is they are generally rounded.

[0062] In an aspect of the invention the particles are characterized by an aspect ratio of 0.8 to 1.3. The aspect ratio is defined as the ratio of the longest dimension to the shortest dimension of a particle as determined by image analysis of pictures of the collection of particles taken by Scanning Electron Microscopy as detailed in the Experimental Section. [0063] The method for making the particles

[0064] The collection of particles consisting of the thermoplastic composition as above detailed can be prepared according to a melt extrusion process in which the thermoplastic composition and a soluble material that is immiscible with the thermoplastic composition are mixed, typically in an extruder, at a temperature greater than a melting point or softening temperature of the thermoplastic composition and at a shear rate sufficiently high to disperse the thermoplastic composition in the soluble material; the molten mixture is then cooled to below the melting point or softening temperature of the thermoplastic composition to form a solidified matrix comprising thermoplastic composition particles; which are then separated from the soluble material.

[0065] The term “immiscible” is used to refer to a mixture of components that when combined form two or more separated phases.

[0066] The term “soluble” is used in its conventional meaning to refer to a material which is able to be dissolved.

[0067] In a preferred embodiment, the process comprises the steps of:

- mixing a mixture comprising the thermoplastic composition comprising at least one semi-aromatic polyamide as defined above and a soluble material that is immiscible with the thermoplastic composition at a temperature greater than a melting point or glass transition temperature of the thermoplastic composition and at a shear rate sufficiently high to disperse the thermoplastic composition in the soluble material that is immiscible with the thermoplastic composition;

- cooling the mixture to below the melting point or glass transition temperature of the thermoplastic composition to form solidified pellets, strands, or paste comprising the thermoplastic composition dispersed in the soluble material; and

- contacting the solidified pellets, strands or paste with a solvent capable of selectively dissolving the soluble material obtaining a collection of particles consisting of the thermoplastic composition; and

- optionally drying the collection of particles.

[0068] The particles have an average particle size D(v, 0.5) of 0.1 to 50.0 μm and a particle size distribution as defined by relationship (I). [0069] For the avoidance of doubts, the expression “soluble material” is hereinafter used to refer to the soluble material that is immiscible with the thermoplastic composition.

[0070] The soluble material is not specifically limited, provided it can be processed at a temperature greater than a melting point or glass transition temperature of the thermoplastic composition and that it can be dissolved by a solvent incapable of dissolving the thermoplastic composition. The soluble material is preferably a material that can be molten or softened at such temperatures that the thermoplastic composition is molten or softened, for example, at 100° C to 300° C. Additionally, the soluble material can be kneaded with the thermoplastic composition and form a separate phase when in molten or solidified state.

[0071] In a preferred embodiment, the soluble material is a water-soluble material. Examples of such water-soluble materials include but are not limited to saccharides including monosaccharides, oligosaccharides, polysaccharides, sugar alcohols, polydextroses, maltodextrin, and inulin; and water-soluble resins. Among water soluble polymers, mention can be made of linear polymers having a hydrophilic group such as -O- , -CONH-, - COOH, or -OH. Examples include polyacrylamides, poly(acrylic acid)s, poly(methacrylic acid)s, poly(itaconic acid)s, poly(vinyl alcohol)s, polyethylene oxide) and its copolymers, polypropylene oxide) and its copolymers, as well as polyesters comprising recurring units deriving from alkylene oxide. Each of these water soluble materials can be used alone or in combination.

[0072] In a preferred embodiment, the soluble material is selected from the group consisting of the water soluble polymers. More preferably, the water soluble material is selected from the group consisting of polyethylene oxide), its copolymers and polyesters comprising recurring units derived from alkylene oxide.

[0073] The polyethylene oxide) suitable for the process of the invention typically has a number average molecular weight Mn in the range of 2,000 to 200,000 g/mol, preferably 15,000 to 150,000 g/mol. Advantageous results were obtained with a polyethylene oxide) having a molecular weight Mn in the range of 15,000 to 45,000 g/mol. [0074] Examples of water soluble polyester polymers comprising recurring units deriving from ethylene oxide include polyesters comprising recurring units deriving from :

- at least one dicarboxylic acid component, and

- at least one diol component, wherein at least 2 mol% of the diol component is a poly(alkylene oxide) of formula: H(O-C_PH2_P)q-OH, wherein p is an integer from 2 to 4, preferably p is 2, and q varies from 2 to 10.

[0075] Suitable polyesters may additionally comprise recurring units derived from a difunctional monomer containing at least one SO₃M group attached to an aromatic moiety, wherein M is H or a metal ion selected from the group consisting of sodium, potassium, calcium, lithium, magnesium, silver, aluminium, zinc, nickel, copper, palladium, iron, and cesium, preferably from the group consisting of sodium, lithium and potassium. The functional groups are carboxy. Illustrative examples of such polyesters are those commercially available under the trade name AQ Polymers by Eastman, especially those having a glass transition temperature ranging from about 25°C to about 50°C. Most preferred is Eastman AQ 38S which is a polyester identified as a diethylene glycol/cyclohexanedimethanol/isophthalate/sulfoisophthalate polyester or Eastman AQ 48 which is a sulfopolyester.

[0076] The amount of the soluble material in the mixture with the thermoplastic composition can be 30 wt% to 95 wt%, 35 wt% to 85 wt%, even 40 wt% to 80 wt%, based on the total weight of the mixture.

[0077] Good results in terms of the particle size and particle size distribution were obtained when processing a polyamide comprising recurring units of formula 9T with a poly(ethylene glycol) having a molecular weight of 30,000 to 45,000 g/mol in a 50:50 weight ratio.

[0078] In cases where the thermoplastic composition comprises, in addition to the semi-aromatic polyamide, additives or additional thermoplastic polymers, these can be added to the mixture before melt mixing with the immiscible material takes place. The additional components may be mixed with the semi-aromatic polyamide either physically or in a melt-blending equipment. The additional components may be blended with the thermoplastic polymer just prior to making the mixture or well in advance. [0079] More generally, the step of mixing the mixture of the thermoplastic composition and the soluble material can take place with any suitable device. Endless screw mixers, stirrer mixers or twin screw extruders compatible with the temperature needed to melt the mixture can be used. The amount of energy applied to this step may be adjusted so as to control the size of the particles obtained therefrom. The skilled person in the art can adjust the equipment (e.g. screw geometry) and the parameters of the equipment (e.g. rotation speed) to obtain particles of the desired size.

[0080] The expression “mixing a mixture” when related to the thermoplastic composition and the soluble material encompasses both the case in which the mixture is prepared in a device separate from the device performing the mixing step as well as the case in which the device is the same.

[0081] According to an embodiment:

- in case a semi-crystalline semi-aromatic polyamide is used, the step of mixing takes place at a temperature chosen to be at least 10°C above the melting temperature (Tm) of the polymer or of the thermoplastic composition comprising the semi-crystalline semi-aromatic polyamide, for example at least 15°C or 20°C above Tm,

- in case an amorphous semi-aromatic polyamide is used, the step of mixing takes place at a temperature chosen to be of at least 50°C above the glass transition temperature (Tg) of the amorphous polymer or of the thermoplastic composition comprising the amorphous semi-aromatic polyamide.

[0082] According to a preferred embodiment, the step of mixing takes place at a temperature above 250°C, for example above 260°C, above 270°C or above 280°C.

[0083] The step of mixing typically is carried out at a temperature lower than the temperature at which the thermoplastic composition starts to decompose.

[0084] The step consisting in processing the mixture into pellets, strands or a paste can be carried out by a process of extrusion through a die.

[0085] The steps of mixing and processing into pellets, strands or a paste preferably take place in an extruder equipped with an extrusion die.

[0086] The step of cooling is conducted by any appropriate means, at a temperature lower than 80°C, for example lower than 50°C. Mention can notably be made of air cooling or quenching in a liquid, for example in water.

[0087] The stage of contacting the pellets, strands or a paste with a solvent capable of selectively dissolving the soluble material may consist in a step of immersing the same into one or more than one bath containing the selected solvent. The solvent, preferably water, is optionally heated to a temperature of up to 95°C, for example to a temperature of about 40°C, about 60°C or about 80°C. The solvent, in particular when it is water, can also be supplemented with an acid or a base, for example selected from the group consisting of potassium hydroxide, sodium hydroxide, lithium hydroxide, potassium carbonate, sodium carbonate, lithium carbonate, organic amines, hydrochloric acid and sulfuric acid. This step may facilitate the dissolution or dispersion of the soluble material so as to recover the particles of the thermoplastic composition.

[0088] The steps of the process of the present invention can be carried out batch- wise or continuously.

[0089] According to an embodiment, the steps of cooling the pellets, paste or strands at a temperature below 80°C, for example lower than 50°C and contacting said pellets, paste or strands with the solvent, in particular water, for example by immersion of the pellets or strands into the solvent, can be carried out simultaneously in the same equipment.

[0090] The process of the invention may also comprise an additional step of drying of the particles, and/or an additional step of sieving the particles. The step of drying can for example take place in a fluidized bed.

[0091] Use of the particles to make a composite material

[0092] The collection of particles of the invention are particularly suited for use in the preparation of composite materials comprising continuous fibers and a matrix of the thermoplastic composition.

[0093] As used herein, the term "fiber" has its ordinary meaning as known to those skilled in the art and may include one or more fibrous materials adapted for the reinforcement of composites, which may take the form of any of particles, flakes, whiskers, short fibers, continuous fibers, sheets, plies, and combinations thereof. [0094] Accordingly, a further object of the invention is a process of producing a composite material comprising a fibrous material of continuous fibers and a matrix comprising the thermoplastic composition detailed above, said process comprising: i) the immersion of said fibrous material in a bath containing an aqueous dispersion comprising the collection of particles consisting of the thermoplastic composition which is the first object of the invention; and ii) drying of said fibrous material.

[0095] The impregnation step of the fibrous material is performed by passing the material through a continuous impregnating device comprising an immersion tank containing an aqueous dispersion comprising the collection of particles as detailed above.

[0096] The collection of particles consisting of the thermoplastic composition is mixed with water to form this dispersion. The concentration of the particles in the dispersion may vary and can be adjusted by the person skilled in the art based on the content of the thermoplastic composition required in the final composite material.

[0097] The fibrous material is caused to circulate in the bath formed by the aqueous dispersion. The median size D(v, 0.5) of the particles in the aqueous dispersion is 0.1 to 50.0 μm, so that they can penetrate into the fiber. Preferably, the median size of the particles D(v, 0.5) is between 2.5 μm to 40.0 μm, preferably from 5.0 μm to 30.0 μm, or from 7.5 μm to 25.0 μm.

[0098] The median size of the particles D(v, 0.5) may be conveniently selected as a function of the diameter of the fibrous material to be impregnated. The median size of the particles D(v, 0.5) may advantageously be from 1 .0 to 4.0 times the average diameter of the fibrous material to be impregnated, even from 1 .0 to 3.5 times.

[0099] The distribution of the particle sizes is such that relationship (I), even (la) or (lb) is met. Without being bound by theory it is believed that a particle size distribution skewed towards the larger particle sizes, as represented by relationship (I) among the D(v, 0.1), D(v, 0.5) D(v, 0.9) values of the particle size distribution, is advantageous in the operation of a slurry impregnation process as it reduces the risk of frothing which may be caused by the particles having smaller diameter when forming the slurry.

[00100] The aqueous dispersion (or slurry) comprising the collection of particles may comprise additional ingredients. These may be for instance emulsifiers or dispersing agents to improve the stability of the slurry during the impregnation process.

[00101] The aqueous dispersion may also contain additives that need to remain in the final composite material. Non limiting examples are for instance inorganic additives.

[00102] The pre-impregnated fibrous material leave the tank and are directed towards a drying device for evaporation of water. Any drying device can be used for evaporating water in this step.

[00103] The constituent fibers of the fibrous material can be conveniently selected from the group consisting of carbon fibers, glass fibers, basalt fibers, silica fibers, silicon carbide fibers, aramid fibers. Fibers of plant origin can also be used. Mention can be made of natural flax, hemp, silk in particularly spider silk, sisal fibers and other cellulose fibers.

[00104] These constituent fibers can be used alone or in a mixture.

[00105] The chosen fibers can be single-strand, multi-strand or a mixture of both. In addition they may have several geometries. They may therefore be in the form of short fibers, then producing felts or nonwovens in the form of strips, sheets, braids, ravings or pieces. Alternatively they can be in the form of continuous fibers producing 2D fabrics, fibers or rovings of unidirectional fibers (UD) or nonwovens. The constituent fibers of the fibrous material may also be in the form of a mixture of these reinforcing fibers having different geometries. Preferably, the fibers are continuous.

[00106] Preferably, the fibrous material is composed of continuous fibers of carbon, glass or silicon carbide or a mixture thereof, in particular carbon fibers.

[00107] Thanks to the size of the inventive particles of thermoplastic composition, the thermoplastic composition is uniformly and homogeneously distributed around the fibers. In this type of material, the impregnating thermoplastic polymer must be distributed as homogeneously as possible within the fibers to obtain minimum porosities i.e. voids between the fibers. The presence of porosities in this type of material may act as stress-concentrating points when subjected to a mechanical tensile stress for example and then form rupture initiation points in the composite material causing mechanical weakening. Homogeneous distribution of the polymer matrix therefore improves the mechanical strength and homogeneity of the composite material.

[00108] Typically, the volume percentage of thermoplastic composition relative to the fibrous material varies from 40 to 25%, preferably from 45 to 125%, and more preferably from 45 to 80%.

[00109] The composite materials obtained are semi-finished products in the form of tapes or sheets with calibrated thickness and width used for the manufacture of three-dimensional structural parts. They can be used to manufacture articles in transport sectors such as automobile, aviation, nautical or rail; renewable energies in particular wind energy, hydrokinetic energy; energy storage devices, solar panels; thermal protection panels; sports and leisure equipment, health and medicine equipment, smart devices; gas storage or transportation devices. The composite materials obtained from the process of the invention may advantageously be used in the manufacture of hydrogen gas storage or transportation tanks.

[00110] The embodiments above are intended to be illustrative and not limiting. Additional embodiments are within the inventive concepts. In addition, although the present invention is described with reference to particular embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention.

[001111 EXAMPLES

[00112] MATERIALS

[00113] PA9T : semi-aromatic polyamide commercially available from Kuraray as GENESTAR GC98018. It is 50:50 copolymer 1 ,9-nonanediamine and terephthalic and 2-methyl-1 ,8-octanediamine and terephthalic acid.

[00114] PEG-1 : polyethylene oxide) , Mn -35000 g/mol (PolyglyKol 35000 S, available from Clariant) was used as the soluble material

[00115] Example 1 - Particle preparation using melt emulsification process

[00116] A Leistritz corotative twin screw extruder (D=18 mm ; L/D=60) was used.

Pellets of PA9T and of PEG-1 (50:50 wt ratio) were both added in the 1st zone of the extruder and an open barrel was used in zone no. 9 for degassing with 10 heating zones used. The first one was heated at 20 °C, the second one was heated at 270 °C, and the third at 290 °C. The temperature of 290°C was applied up to the last zone. The screw speed applied was about 200 rpm. The throughput was 8 kg/hr, with 4 kg/hr per feeder. The resulting melted particles surrounded by melted PEG-1 were collected into a flask containing cold water to provide a slurry containing the PA9T particles. The particles were recovered by centrifugation. Washing and centrifugation steps (from 1 to 5 times) were applied to remove the PEG-1 . Particles were then dried at 90°C.

[00117] The particles properties are summarized in Table 1 below.

[00118] Comp. Example 1

[00119] PA9T reactor flake was milled using a Fluid Energy Model 4 micro jet mill, with a liquid nitrogen cooled material inlet. The mill was run with a P1 inlet pressure of 621 kPa, mill pressure P2 of 414 kPa, and a feed rate of 0.5 kg/hr. The resulting powder was collected and analyzed, with the particle properties summarized in Table 1 below.

[00120] Particle size determination

[00121] The particle size distributions of the polymer powders were determined by a wet method using a MicroTrac S3500 laser diffraction instrument. The S3500 measures particle size in a range from 0.02 to 2,800 μm. The powders of Example 1 and Comp. Example 1 were dispersed in isopropanol. A laser beam is projected through a sample cell that contains the stream of moving particles suspended in isopropanol. The light rays that strike the particles are scattered, and the scattered light is measured by photo detector arrays. The photodetector array measures the quantity of light (flux) at specific angles. Electrical signals proportional to the measured light flux values are then processed by the computer/software to form a multichannel histogram of the particle size distribution. Particle size distributions are reported by volume in Table 1.

Table 1

[00118] Particle aspect ratio

[00119] The powder samples of Example 1 and Comp. Example 1 were dispersed onto carbon tape using an applicator stick, and then imaged by variable pressure scanning electron microscopy (SEM). The resulting image files were analyzed in ImageJ to measure particle length and width. Length was measured along the longest dimension of the particle, while width was measured along the shortest dimension of the particle.

[00120] The particle aspect ratio was calculated as length/width. A series of 10 particles were randomly chosen from one image for each set of powder samples, with the length and width measured for each of these individual particles. Finally, an average and standard deviation were calculated for the aspect ratio parameter.

[00121] The particles of Example 1 have an aspect ratio of 1.1 ± 0.1 , which is an indication of particles having a rounded quasi-spherical shape.

[00122] The particles of Comparative Example 1 have an aspect ratio of 1 .7 ± 0.5.

[00123] General procedure for preparation of composite material

[00124] A slurry-based impregnation process was employed to create unidirectional carbon fiber tapes impregnated with the polymer particles of Example 1 and Comparative Example 1.

[00125] Unsized Carbon fibers commercially available from Hyosung under the trade name TANSOME H2550 12K were used. They are supplied in the form of a tow comprising 12,000 individual fibers. The individual fiber thickness is about 7 μm. A sufficient number of fibers were used to make a 76 mm wide unidirectional tape. The dry web of collimated, continuous fibers were passed through an aqueous bath containing water, the polymer particles of Example 1 or Comparative Example 1 , and a surfactant (Igepal CA-630, supplied by Sigma Aldrich). [00126] At start of the run, the aqueous bath initially contained 297 g of polymer and 29.5 kg of water. A separate, second tank was created to contain 882.5 g polymer, 4.4 g surfactant, and 5.0 kg of water. This tank served as a concentrated recharge tank to the first tank, as the rate of loss of polymer in the main aqueous bath does not match the rate of water loss during a typical slurry impregnation process. A stream of recharge liquid from the recharge tank was pumped into the main slurry bath, at a rate sufficient to maintain a targeted fiber volume fraction (Vf) of 0.60, as determined by weight checks throughout the run.

[00127] The line was allowed to equilibrate for 1 .5 hours prior to collecting the prepreg tape. After passing through the aqueous bath, the web of collimated fibers was passed underneath a series of infrared lamps which facilitated evaporation of the water and consolidation of the polymer. The tape was then passed through a die heated to 340 °C, then through a heated calendar maintained at 120 °C, and then a series of cooling rolls before being coiled onto a cardboard core. The line speed was set at 1 .0 m /sec. The prepreg tape had a nominal fiber volume fraction of 0.60, which resulted in a final polymer content of 32 wt %, and a fiber areal weight of 124 g/m²

[00128] The two tapes made from the particles of Example 1 and Comparative Example 1 were cut, mounted in epoxy, and polished in such a manner to display the tape cross-section. The polished tape pucks were then imaged using optical microscopy. The detailed sample preparation and imaging procedure is detailed hereafter.

[00129] Sample preparation: Samples of unidirectional tape were cut perpendicular to the fibre direction before being stabilised and set with a two component epoxy resin (such as Epoxicure 2™ from Buehler). After curing, the puck was progressively abraded and polished using first sandpaper, and then a diamond slurry on a felt pad. Sandpaper grits of 280/P320 to 1200/P4000 are appropriate for the initial abrasion, and then diamond slurries with a particle size of 3.0 μm, then 1.0 μm, and finally 0.1 μm are useful for polishing; a suitable slurry would be from the Glennel® Diamond Suspension range from Electron Microscopy Sciences. [00130] Imaging: The polished samples were imaged using an optical microscope under different magnification levels (100-300x).

[00131] The volume fractions of fibre, matrix and porosity were extrapolated via image analysis using ImageJ software. The colour thresholding was progressively adjusted to make an image of only black and white pixels, such that porosity, i.e. voids, remains black, and fibre and matrix both appear white; this was then repeated to generate an image in which both porosity and matrix is black, and fibre only is white; pixels were counted in each resulting image allowing a simple calculation of the fraction of each component.

[00132] The tape made from Comparative Example 1 contained relatively high amounts of porosity, resin-rich areas, splits/gaps within the tape width, and highly inconsistent tape thickness across its width. The porosity was calculated to be in the order of 10%.

[00133] In contrast, the tape made from Example 1 possessed uniform tape thickness across the tape width with few splits/gaps, and a very even fiber distribution with minimal porosity or resin-rich areas. The porosity was calculated to be in the order of 1%.

[00134] Laminate Preparation and characterization

[00135] Composite laminates were prepared on a Rucks KV 275.11 Upstroke Press equipped with 600 mm x 600 mm, a maximum platen temperature of 450 °C, and a maximum press force of 1000 kN. The tape was dried for 18 h at 120°C Overnight, then annealed at 150 °C for 10 min. The ply stack was wrapped in Kapton(R) tape and sandwiched between aluminum sheets, and Zyvax Composite Shield Release was applied. The prepared ply stack was loaded into a 18 cm x 28 cm tool and placed into the press. The prepared mold was then heated according to the procedure displayed in Table 2.

Table 2

[00136] Samples were cut from the resulting laminates and tested according to the ASTM standards displayed in Table 3.

Table 3

[00137] The composite laminates obtained from the polymer particles of Example 1 demonstrated significantly higher flex modulus, maximum flex stress, and short beam shear strength as compared to laminates made from the particles of Comparative Example 1.

Claims

Claims

1 . A collection of particles wherein the particles consist of a thermoplastic composition comprising at least one semi-aromatic polyamide; and wherein the particles have a median particle size on a volume basis, D(v, 0.5), from 0.1 to 50.0 μm and a particle size distribution such that the following relationship (I) is met:

in which D(v, 0.9) is the size of particle below which lies 90% of the sample; D(v, 0.5) is the size of particle at which 50% of the sample is smaller and 50% is larger; D(v, 0.1) is the size of particle below which lies 10% of the sample.

2. The collection of particles of claim 1 wherein particle size distribution is such that the following relationship (II) is met:

3. The collection of particles of any one of claim 1 or 2 wherein D(v, 0.9) is 100.0 μm or less, 65.0 μm or less, 50.0 μm or less and/or D(v, 0.1) is at least 1 .0 μm, at least 2.5 μm, at least 5.0 μm.

4. The collection of particles of any one of the preceding claims wherein D(v, 0.5) is from 1 .0 to 50.0 μm, from 2.5 μm to 40.0 μm, preferably from 5.0 μm to 30.0 μm, even from 7.5 μm to 25.0 μm.

5. The collection of particles of any one of the preceding claims characterized by a particle size distribution such that the following relationship is met:

6. The collection of particles of any one of the preceding claims wherein the semi-aromatic polyamide comprises recurring units of formula XT, wherein X represents units deriving from an aliphatic diamine having 8 to 36 carbon atoms, preferably 8 to 14 carbon atoms or it comprises recurring units of formula MXDZ in which Z represents units deriving from a linear or branched, aliphatic or cyclo-aliphatic diacid having z carbon atoms, wherein z is an integer equal to or greater than 6, preferably from 6 to 36, and MXD is m- xylylenediamine. The collection of particles of any one of the preceding claims wherein the semi-aromatic polyamide is selected from the group consisting of PA 6T, PA 8T, PA Me8T, PA 9T, PA Me8T/9T, PA 10T, PA 11T, PA 12T, PA 6T/9T, PA 9T/10T, PA 9T/11T, PA 9T/12T, PA 6T/10T, PA 6T/11T, PA 6T/12T, PA 10T/11T, PA 10T/12T, PA 11T/12T, PA 10/6T, 6 PA 10/9T, PA 10/10T, PA 10/11T, PA 10/12T, PA 11/6T, PA 11/9T, PA 11/10T, PA 11/11T, PA 11/12T, PA 12/6T, PA 12/9T, PA 12/10T, PA 12/11T, PA 12/12T, PA 610/6T, PA 612/6T, PA 910/6T, PA 912/6T, PA 1010/6T, PA 1012/6T, PA 610/9T, PA 612/9T, PA 910/9T, PA 912/9T, PA 1010/9T, PA 1012/9T, PA 610/10T, PA 612/10T, PA 910/10T, PA 912/10T, PA 1010/10T, PA 1012/10T, PA 610/12T, PA 612/12T, PA 910/12T, PA 912/12T, PA 1010/12T, PA 11/6T/9T, PA

11/6T/10T, PA 11/6T/11T, PA 11/6T/12T, PA 11/9T/10T, PA 11/9T/11T, PA 11/9T/12T, PA 11/10T/11T, PA 11/10T/12T, PA 11/11T/12T, PA 12/6T/10T, PA 12/6T/11T, PA 12/6T/12T, 12/9.T/10.T, PA 12/9T/11T, PA 12/9T/12T, PA 12/10T/11T, PA 12/10T/12T, PA 12/11T/12T, PA MXDT/10T, PA MPMDT/10T, PA BACT/10T, PA BACT/6T, PA BACT/10T/6T, PA MXD6, PA MXD10. The collection of particles of any one of the preceding claims wherein the thermoplastic composition comprises at least one semi-aromatic polyamide and 0.1 to 40.0 wt% of at least one additional ingredient selected from the group consisting of plasticizers, fillers, impact modifiers. A process for the manufacture of the collection of particles of any one of the preceding claims comprising the steps of:

- mixing a mixture comprising thermoplastic composition comprising at least one semi-aromatic polyamide and a soluble material that is immiscible with the thermoplastic composition at a temperature greater than a melting point or glass transition temperature of the thermoplastic composition and at a shear rate sufficiently high to disperse the thermoplastic composition in said soluble material;

- cooling the mixture to below the melting point or glass transition temperature of the thermoplastic composition to form solidified pellets, strands, or paste comprising the thermoplastic composition dispersed in the soluble material; and - contacting the solidified pellets, strands or paste with a solvent capable of selectively dissolving the soluble material obtaining a collection of particles consisting of the thermoplastic composition; and

- optionally drying the collection of particles. . The process of claim 9 in which the soluble material is a water-soluble material, preferably selected from the group consisting of saccharides including monosaccharides, oligosaccharides, polysaccharides, sugar alcohols, polydextroses, maltodextrin, and inulin, polyacrylamides, poly(acrylic acid)s, poly(methacrylic acid)s, poly(itaconic acid)s, poly(vinyl alcohol)s, polyethylene oxide) and its copolymers, polypropylene oxide) and its copolymers, as well as polyesters comprising recurring units deriving from alkylene oxide. . The process of claim 9 or 10 in which the soluble material is polyethylene oxide) having a molecular weight Mn in the range of 15,000 to 45,000 g/mol.. The process of any one of claims 9 to 11 in which the amount of the soluble material in the mixture with the thermoplastic composition is 30 wt% to 95 wt%, 35 wt% to 85 wt%, even 40 wt% to 80 wt%, based on the total weight of the mixture. . The process of any one of claims 9 to 12 wherein the semi-aromatic polyamide comprises recurring units of formula 9T, the soluble material is a polyethylene glycol) having a molecular weight of 30,000 to 45,000 g/mol and the thermoplastic composition comprising at least one semi-aromatic polyamide and the soluble material are in a 50:50 weight ratio in the mixture.. The process of claim 13 in which the step of mixing takes place at a temperature above 260°C, above 270°C or above 280°C. . A liquid composition comprising the collection of particles of any one of claims 1 to 8 and water. . A process for making a composite material comprising a fibrous material of continuous fibers and a matrix comprising a thermoplastic composition, said process comprising: i) the immersion of said fibrous material in a bath containing an aqueous dispersion comprising the collection of particles of any one of claims 1 to 8; and ii) drying of said fibrous material. Process according to claim 16, wherein said continuous fibers comprise continuous fibers selected from carbon fibers; glass; silicon carbide; basalt; silica; natural fibres, in particular flax or hemp, lignin, bamboo, sisal, silk, or cellulosic, in particular viscose. The process according to claim 16 or 17 further comprising the step of preparing a collection of particles according to the process of claims 9 to 14. A composite material comprising continuous fibers and a thermoplastic polymer matrix comprising a semi-aromatic polyamide said composite material being obtained from the process of any one of claims 16 to 18. Use of the composite material of claim 19, in the manufacture of three- dimensional composite parts. Use according to claim 20, wherein said manufacture of said composite parts relates to the fields of transport, oil and gas, gas storage, civil aviation or military, nautical, railway; renewable energy, thermal protection panels; sports and recreation, smart devices, health and medical. .Articles, including gas storage and transportation tanks, comprising the composite material of claim 19.