POLYAMIDE COMPOSITIONS COMPRISING RECYCLED CARBON FIBERS AND USES THEREOF

Abstract

The present invention relates to a molding composition comprising by weight: a) from 50 to 99% of a semi-crystalline aliphatic polyamide having an inherent viscosity of less than or equal to 1.10, in particular less than or equal to 1.00, in particular less than or equal to 0.95, in particular less than or equal to 0.9, as determined according to ISO 307:2007 but using m-cresol instead of sulfuric acid, a temperature of 20°C and a concentration of 0.5% by mass, b) from 1 to 50% of recycled carbon fibers having an average length of less than or equal to 6 mm before compounding, said recycled carbon fibers being surface-coated (sized) with a polyamide, in particular an aliphatic polyamide, c) from 0 to 5% of at least one additive, the sum of components a), b) and c) being equal to 100%.

Description

Title of the invention: POLYAMIDE COMPOSITIONS COMPRISING RECYCLED CARBON FIBERS AND THEIR USES

[0001] The invention relates to polyamide compositions comprising recycled carbon fibers and their uses. Prior art

[0002] In sports-related applications, polyamides and in particular polyamide 11 (PA 11) reinforced with carbon fibers are well known for their rigidity, lightness and high mechanical performance.

[0003] Carbon fiber has been used for many years. The reasons why this type of fiber has become essential are simple: the material produced is extremely strong, durable and ultra-light, characteristics that are highly prized by sports equipment manufacturers looking for lightness, rigidity and longevity.

[0004] Today, the durability of a product is essential for the consumer and has become a key requirement for major sports brands.

[0005] A composition reinforced with carbon fibers will have a strong impact on CO2 emissions, in particular because the production of carbon fibers is highly energy-intensive, and carbon fibers are approximately 100% carbon (C).

[0006] It is therefore necessary to have compositions reinforced by carbon fibers but having a much less significant impact on CO2 emissions, while maintaining high mechanical properties, in terms of modulus, stress, elongation and impact resistance.

[0007] One solution is to use recycled carbon fibers.

[0008] Thus, international application WO 2015 / 074945 describes a molding mass having the following composition:

[0009] (a) from 49 to 97% by weight of at least one plastic material (A) forming a matrix,

[0010] (b) from 3 to 40% by weight of at least one carbon fiber covered with at least one plastic material (B),

[0011] (c) from 0 to 48% by weight of at least one other additive (C),

[0012] The sum of components (a) to (c) representing 100% by weight,

[0013] characterized in that the plastic molding mass has a specific surface resistance of IxlO7 to IxlO22 ohm and a specific volume resistance of IxlO5 to IxlO20 ohm*m, both determined in accordance with IEC 60093.

[0014] Carbon fiber can be recycled or cellulose based, plastic material (B) is selected from the group consisting of polyamides, in particular copolyamides, polyesters, in particular copolyesters, polyurethanes, epoxy resins, polyhydroxyethers, acrylic copolymers, and mixtures or superimposed layers of two or more of these plastics, and the plastic (A) of component (a) is a thermoplastic selected from the group consisting of acetal resins, liquid crystalline polymers, polyacrylates, polymethacrylates, olefinic and cycloolefinic polymers, polyamides, polyamide elastomers, in particular polyetheramides, polyetheramides and polyetheresteramides, polyamide-imides, polyethers, polyarylethers including polyphenylethers, polyhydroxyethers, polycarbonates, polysulfones, polyetherimides, polyimides, polyesters, polyester polycarbonates, polyoxyethylenes, polystyrenes, styrene copolymers, polysulfones,vinyl polymers such as polyvinyl chloride and polyvinyl acetate, and mixtures of two or more of the mentioned thermoplastics, or a duroplast selected from the group consisting of melamine resins, phenoplasts, polyester resins, aminoplasts, epoxy resins, polyurethanes, crosslinked polyacrylates, and mixtures of two or more of the mentioned duroplasts. However, these compositions have the disadvantage of being fragile with an elongation at break of less than 3%.

[0015] It happens that certain recycled materials have been altered by their history and their experience and therefore that their performance, in particular mechanical, is inferior compared to virgin materials, which does not meet the requirements of compositions based on high-performance polymers such as PAU.

[0016] It is therefore necessary to have compositions reinforced by recycled carbon fibers which do not have the disadvantages of impact on CO2 emissions and loss of mechanical properties mentioned above.

[0017] The present invention therefore relates to a molding composition comprising by weight:

[0018] a) from 50 to 99% of a semi-crystalline aliphatic polyamide having an inherent viscosity of less than or equal to 1.10, in particular less than or equal to 1.00, in particular less than or equal to 0.95, in particular less than or equal to 0.9, as determined according to ISO 307:2007 but using m-cresol instead of sulfuric acid, a temperature of 20°C and a concentration of 0.5% by mass,

[0019] b) from 1 to 50% of recycled carbon fibers having an average length of less than or equal to 6 mm before compounding, and surface-coated with a polyamide, in particular an aliphatic polyamide,

[0020] c) from 0 to 5% of additives,

[0021] the sum of components a), b) and c) being equal to 100%.

[0022] The inventors therefore surprisingly found that by selecting a polyamide with suitable inherent viscosity as well as recycled carbon fibers sized with polyamide, it was possible to improve the mechanical performance of polyamide formulations as well as CO2 emissions compared to polyamide formulations reinforced with virgin carbon fibers.

[0023] A molding composition is generally prepared by melt mixing the various ingredients thereof in an extruder, particularly a twin-screw extruder. The compounded material emerges from the extruder in the form of rods which are then cooled and cut into granules.

[0024] The term “before compounding” therefore means that the recycled carbon fibers which are introduced into the extruder at the time of processing have an average length less than or equal to 6 mm.

[0025] With regard to the semi-crystalline aliphatic polyamide (a):

[0026] The nomenclature used to define polyamides is described in ISO 1874-1:2011

[0027] "Plastics - Polyamide (PA) materials for molding and extrusion - Part 1: Designation",

[0028] in particular on page 3 (tables 1 and 2) and is well known to those skilled in the art.

[0029] A semi-crystalline polyamide, within the meaning of the invention, designates a polyamide which presents a

[0030] glass transition temperature (Tg) and a determined melting temperature (Tf)

[0031] respectively according to ISO 11357-2 and 3:2013, and a crystal enthalpy lization during

[0032] the cooling step at a speed of 20K / min in DSC measured according to the ISO 11357-3 standard

[0033] of 2013 greater than 30 J / g, preferably greater than 35 J / g.

[0034] The polyamide may be a homopolyamide or a copolyamide or a mixture thereof.

[0035] The semi-crystalline aliphatic polyamide having an inherent viscosity of less than or equal to 1.10, in particular less than or equal to 1.00, in particular less than or equal to 0.95, in particular less than or equal to 0.9, as determined according to ISO 307:2007 but using m-cresol instead of sulfuric acid, a temperature of 20°C and a concentration of 0.5% by weight, is present in the composition from 50 to 99%, preferably from 60.0 to 90.0%, more preferably from 60.0 to 80.0% by weight, even more preferably from 65.0 to 80.0% by weight, each based on the sum of the constituents of the composition.

[0036] The average number of carbon atoms relative to the nitrogen atom is greater than or equal to 6.

[0037] Advantageously, the semi-crystalline aliphatic polyamide is excluding PA6 and PA66.

[0038] Advantageously, the average number of carbon atoms relative to the nitrogen atom is greater than or equal to 8, in particular greater than or equal to 9, in particular greater than or equal to 10.

[0039] Advantageously, the average number of carbon atoms relative to the nitrogen atom is greater than or equal to 8 and the semi-crystalline aliphatic polyamide is excluding PA612.

[0040] In the case of a homopolyamide of type PA-XY, the number of carbon atoms per nitrogen atom is the average of the X unit and the Y unit.

[0041] In the case of a copolyamide, the number of carbons per nitrogen is calculated according to the same principle. The calculation is carried out in molar proportion to the different amide units.

[0042] In a first embodiment:

[0043] In a first variant of this first embodiment, the semi-crystalline aliphatic polyamide is obtained from the polycondensation of at least one aminocarboxylic acid comprising from 6 to 18 carbon atoms, preferably from 9 to 18 carbon atoms, more preferably from 10 to 18 carbon atoms, even more preferably from 10 to 12 carbon atoms. It can thus be chosen from 6-aminohexanoic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid, 13-aminotridecanoic acid, 14-aminotetradecanoic acid, 15-aminopentadecanoic acid, 16-aminohexadecanoic acid, 17-aminoheptadecanoic acid, 18-aminooctadecanoic acid.

[0044] Preferably, it is obtained from the polycondensation of a single aminocarboxylic acid.

[0045] In a second variant of this first embodiment, the semi-crystalline aliphatic polyamide is obtained from the polycondensation of at least one lactam comprising from 6 to 18 carbon atoms, preferably from 9 to 18 carbon atoms, more preferably from 10 to 18 carbon atoms, even more preferably from 10 to 12 carbon atoms.

[0046] Preferably, it is obtained from the polycondensation of a single lactam.

[0047] In a third variant of this first embodiment, the semi-crystalline aliphatic polyamide is obtained from the polycondensation of at least one aliphatic diamine comprising from 4 to 36 carbon atoms, advantageously from 6 to 18 carbon atoms, advantageously from 6 to 12 carbon atoms, advantageously from 10 to 12 carbon atoms and at least one aliphatic dicarboxylic acid comprising from 4 to 36 carbon atoms, advantageously from 6 to 18 carbon atoms. of carbon, advantageously from 6 to 12 carbon atoms, advantageously from 10 to 12 carbon atoms.

[0048] The aliphatic diamine used to obtain this XY repeating unit is an aliphatic diamine which has a linear main chain comprising at least 4 carbon atoms.

[0049] This linear main chain may, where appropriate, comprise one or more methyl and / or ethyl substituents; in this latter configuration, we speak of a "branched aliphatic diamine". In the case where the main chain does not comprise any substituent, the aliphatic diamine is called a "linear aliphatic diamine".

[0050] Whether or not it comprises methyl and / or ethyl substituents on the main chain, the aliphatic diamine used to obtain this repeating unit XY comprises from 4 to 36 carbon atoms, advantageously from 4 to 18 carbon atoms, advantageously from 6 to 18 carbon atoms, advantageously from 6 to 14 carbon atoms.

[0051] When this diamine is a linear aliphatic diamine, it then corresponds to the formula H2N-(CH2)X-NH2 and can be chosen for example from butanediamine, pentanediamine, hexanediamine, heptanediamine, octanediamine, nona-nediamine, decanediamine, undecanediamine, dodecanediamine, trideca-nediamine, tetradecanediamine, hexadecanediamine, octadecanediamine and octadecenediamine. The linear aliphatic diamines which have just been cited can all be bio-resourced within the meaning of standard ASTM D6866.

[0052] When this diamine is a branched aliphatic diamine, it can in particular be 2-methylpentanediamine, 2-methyl-1,8-octanediamine or trimethylene (2,2,4 or 2,4,4) hexanediamine.

[0053] The dicarboxylic acid may be chosen from aliphatic, linear or branched dicarboxylic acids.

[0054] When the dicarboxylic acid is aliphatic and linear, it can be chosen from succinic acid (4), pentanedioic acid (5), adipic acid (6), heptanedioic acid (7), octanedioic acid (8), azelaic acid (9), sebacic acid (10), undecanedioic acid (11), dodecanedioic acid (12), brassylic acid (13), tetradecanedioic acid (14), hexadecanedioic acid (16), octadeca-nedioic acid (18), octadecenedioic acid (18), eicosanedioic acid (20), do-cosanedioic acid (22) and fatty acid dimers containing 36 carbons.

[0055] The above-mentioned fatty acid dimers are dimerized fatty acids obtained by oligomerization or polymerization of long-chain unsaturated monobasic hydrocarbon fatty acids (such as linoleic acid and oleic acid), as described in particular in document EP 0 471 566.

[0056] In a fourth variant of this first embodiment, the polyamide ali- semi-crystalline phatic is obtained from a mixture of these three variants.

[0057] In a second embodiment:

[0058] In a first variant of this second embodiment, the semi-crystalline aliphatic polyamide is obtained from the polycondensation of at least one aminocarboxylic acid comprising from 6 to 18 carbon atoms, preferably from 8 to 12 carbon atoms, more preferably from 10 to 12 carbon atoms.

[0059] Preferably, it is obtained from the polycondensation of a single aminocarboxylic acid.

[0060] In a second variant of this second embodiment, the semi-crystalline aliphatic polyamide is obtained from the polycondensation of at least one lactam comprising from 6 to 18 carbon atoms, preferably from 8 to 12 carbon atoms, more preferably from 10 to 12 carbon atoms.

[0061] Preferably, it is obtained from the polycondensation of a single lactam.

[0062] In a third embodiment, said semi-crystalline polyamide is chosen from PA610, PA612, PA1010, PA1012, PA1212, PAU and PA12, in particular PA1010, PA1012, PA1212, PAU, PA12.

[0063] Advantageously, said semi-crystalline polyamide is chosen from PA11 and PA12, in particular PAU.

[0064] In one embodiment, said semi-crystalline polyamide of said composition consists of at least 30% by weight, in particular at least 50% of recycled semi-crystalline polyamide. Regarding carbon fibers

[0065] The recycled carbon fibers in the semi-crystalline aliphatic polyamide molding composition according to the invention are preferably present from 1.0 to 50.0% by weight, preferably from 10.0 to 40.0%, more preferably from 20.0 to 40.0% by weight, even more preferably from 25.0 to 40.0% by weight, each based on the sum of the constituents of the composition.

[0066] The recycled carbon fibers used in the semi-crystalline aliphatic polyamide molding composition may be in the form of chopped (or short) fibers or in the form of bundles of chopped (or short) fibers or in the form of ground carbon fibers.

[0067] Before compounding, the carbon fibers are preferably cut (or short) carbon fibers and have an average length of 0.1 to 6 mm, in particular 2 to 6 mm.

[0068] Before compounding, the ground carbon fibers have an average length of 50 μm to 400 μm.

[0069] After compounding, in the molding composition, the ground carbon fibers have an average length of less than 400 μm.

[0070] After compounding, in the molding composition, the short carbon fibers have an average length of 100 to 600 pm, in particular 150 to 500 pm.

[0071] The recycled carbon fibers used are surface coated (sized). A coating (sized) must be compatible with the plastic matrix in order to ensure good coating, good adhesion and the best possible reinforcing effect.

[0072] The polyamide sizing of the recycled carbon fiber may be a semi-aromatic polyamide or an aliphatic polyamide or a mixture thereof.

[0073] Advantageously, said polyamide is an aliphatic polyamide.

[0074] Examples of aliphatic polyamides, in particular semi-crystalline ones, are given above.

[0075] Advantageously, the recycled carbon fibers are sized with said polyamide, in particular said aliphatic polyamide, in a range from 0.5 to 6%, in particular from 1 to 5%, in particular from 1.5 to 4% by weight relative to the total carbon fibers-size.

[0076] In one embodiment, the carbon footprint of the recycled carbon fibers is at least halved compared to the footprint of the virgin carbon fibers as determined according to the LCA (Life Cycle Analysis) method in order to determine the environmental impact following in particular the international standards ISO 14040:2006, ISO 14044:2006 and / or ISO 14067:2018. Regarding additives (c)

[0077] The additive is optional and comprised from 0 to 5.0%, in particular from 0.1 to 5.0% by weight.

[0078] The additive is chosen from fillers, glass beads, colorants, sta bilizants, plasticizers, surfactants, nucleating agents, pigments, brighteners, antioxidants, lubricants, flame retardants, natural waxes and mixtures thereof.

[0079] It is quite obvious that the charges are excluding recycled or non-recycled carbon fibers.

[0080] Advantageously, the additive is chosen from fillers, colorants, stabilizers, plasticizers, surfactants, nucleating agents, pigments, brighteners, antioxidants, flame retardants, natural waxes and mixtures thereof.

[0081] For example, the stabilizer may be a UV stabilizer, an organic stabilizer or more generally a combination of organic stabilizers, such as a phenol-type antioxidant (for example of the type of irganox 245 or 1098 or 1010 from the company Ciba-BASF), a phosphite-type antioxidant (for example irgafos® 126 from the company Ciba-BASF) and possibly other stabilizers such as a HALS, which means Hindered Amine Light Stabilizer or hindered amine light stabilizer (for example Tinuvin 770 from the company Ciba-BASF), an anti-UV (for example Tinuvin 312 from the company Ciba), a phosphorus-based stabilizer. can also use amine-type antioxidants such as Naugard 445 from Crompton or polyfunctional stabilizers such as Nylostab S-EED from Clariant.

[0082] This stabilizer may also be a mineral stabilizer, such as a copper-based stabilizer. Examples of such mineral stabilizers include copper halides and acetates. Alternatively, other metals such as silver may be considered, but these are known to be less effective. These copper-based compounds are typically combined with alkali metal halides, particularly potassium.

[0083] For example, the plasticizers are chosen from benzene sulfonamide derivatives, such as n-butyl benzene sulfonamide (BBSA); ethyl toluene sulfonamide or N-cyclohexyl toluene sulfonamide; hydroxybenzoic acid esters, such as ethyl-2-hexyl parahydroxybenzoate and decyl-2-hexyl parahydroxybenzoate; esters or ethers of tetrahydrofurfuryl alcohol, such as oligoethyleneoxytetrahydrofurfuryl alcohol; and esters of citric acid or hydroxymalonic acid, such as oligoethyleneoxy malonate.

[0084] It would not be outside the scope of the invention to use a mixture of plasticizers.

[0085] For example, the fillers can be chosen from silica, graphite, expanded graphite, carbon black, kaolin, magnesia, slag, talc, wol-lastonite, nanofillers (carbon nanotubes), pigments, metal oxides (titanium oxide), metals, advantageously wollastonite and talc, preferably talc. Regarding the composition

[0086] The molding composition is as defined above and comprises in a first embodiment by weight:

[0087] a) from 50 to 99% of a semi-crystalline aliphatic polyamide having an inherent viscosity of less than or equal to 1.10, in particular less than or equal to 1.00, in particular less than or equal to 0.95, in particular less than or equal to 0.9, as determined according to ISO 307:2007 but using m-cresol instead of sulfuric acid, a temperature of 20°C and a concentration of 0.5% by mass,

[0088] b) from 1 to 50% of recycled carbon fibers having an average length of less than or equal to 6 mm before compounding, said recycled carbon fibers being surface-coated (sized) with a polyamide, in particular an aliphatic polyamide,

[0089] c) from 0 to 5% of at least one additive,

[0090] the sum of components a), b) and c) being equal to 100%.

[0091] Advantageously, it comprises by weight:

[0092] a) from 50 to 98.9% of a semi-crystalline aliphatic polyamide having a viscosity inherent less than or equal to 1.10, in particular less than or equal to 1.00, in particular less than or equal to 0.95, in particular less than or equal to 0.9, as determined according to ISO 307:2007 but using m-cresol instead of sulfuric acid, a temperature of 20°C and a concentration of 0.5% by mass,

[0093] b) from 1 to 50% of recycled carbon fibers having an average length less than or equal to 6 mm before compounding, said recycled carbon fibers being surface-coated (sized) with a polyamide, in particular an aliphatic polyamide,

[0094] c) from 0.1 to 5% of at least one additive,

[0095] the sum of components a), b) and c) being equal to 100%.

[0096] According to a first variant, it comprises by weight:

[0097] a) from 60 to 90% of a semi-crystalline aliphatic polyamide having an inherent viscosity of less than or equal to 1.10, in particular less than or equal to 1.00, in particular less than or equal to 0.95, in particular less than or equal to 0.9, as determined according to ISO 307:2007 but using m-cresol instead of sulfuric acid, a temperature of 20°C and a concentration of 0.5% by mass,

[0098] b) from 10 to 40% of recycled carbon fibers having an average length of less than or equal to 6 mm before compounding, said recycled carbon fibers being surface-coated (sized) with a polyamide, in particular an aliphatic polyamide,

[0099] c) from 0 to 5% of at least one additive,

[0100] the sum of components a), b) and c) being equal to 100%.

[0101] Advantageously, it comprises by weight:

[0102] a) from 60 to 89.9% of a semi-crystalline aliphatic polyamide having an inherent viscosity of less than or equal to 1.10, in particular less than or equal to 1.00, in particular less than or equal to 0.95, in particular less than or equal to 0.9, as determined according to ISO 307:2007 but using m-cresol instead of sulfuric acid, a temperature of 20°C and a concentration of 0.5% by mass,

[0103] b) from 10 to 40% of recycled carbon fibers having an average length of less than or equal to 6 mm before compounding, said recycled carbon fibers being surface-coated (sized) with a polyamide, in particular an aliphatic polyamide,

[0104] c) from 0.1 to 5% of at least one additive,

[0105] the sum of components a), b) and c) being equal to 100%.

[0106] According to a second variant, it comprises by weight:

[0107] a) from 60 to 80% of a semi-crystalline aliphatic polyamide having an inherent viscosity less than or equal to 1.10, in particular less than or equal to 1.00, in particular less than or equal to 0.95, in particular less than or equal to 0.9, such as de- finished according to ISO 307:2007 but using m-cresol instead of sulfuric acid, a temperature of 20°C and a concentration of 0.5% by mass,

[0108] b) from 20 to 40% of recycled carbon fibers having an average length less than or equal to 6 mm before compounding, said recycled carbon fibers being surface coated (sized) with a polyamide, in particular an aliphatic polyamide,

[0109] c) from 0 to 5% of at least one additive,

[0110] the sum of components a), b) and c) being equal to 100%.

[0111] Advantageously, it comprises by weight:

[0112] a) from 60 to 79.9% of a semi-crystalline aliphatic polyamide having an inherent viscosity of less than or equal to 1.10, in particular less than or equal to 1.00, in particular less than or equal to 0.95, in particular less than or equal to 0.9, as determined according to ISO 307:2007 but using m-cresol instead of sulfuric acid, a temperature of 20°C and a concentration of 0.5% by mass,

[0113] b) from 20 to 40% of recycled carbon fibers having an average length of less than or equal to 6 mm before compounding, said recycled carbon fibers being surface-coated (sized) with a polyamide, in particular an aliphatic polyamide,

[0114] c) from 0.1 to 5% of at least one additive,

[0115] the sum of components a), b) and c) being equal to 100%.

[0116] According to a third variant, it comprises by weight:

[0117] a) from 60 to 75% of a semi-crystalline aliphatic polyamide having an inherent viscosity of less than or equal to 1.10, in particular less than or equal to 1.00, in particular less than or equal to 0.95, in particular less than or equal to 0.9, as determined according to ISO 307:2007 but using m-cresol instead of sulfuric acid, a temperature of 20°C and a concentration of 0.5% by mass,

[0118] b) from 25 to 40% of recycled carbon fibers having an average length of less than or equal to 6 mm before compounding, said recycled carbon fibers being surface-coated (sized) with a polyamide, in particular an aliphatic polyamide,

[0119] c) from 0 to 5% of at least one additive,

[0120] the sum of components a), b) and c) being equal to 100%.

[0121] Advantageously, it comprises by weight:

[0122] a) from 60 to 74.9% of a semi-crystalline aliphatic polyamide having an inherent viscosity less than or equal to 1.10, in particular less than or equal to 1.00, in particular less than or equal to 0.95, in particular less than or equal to 0.9, as determined according to ISO 307:2007 but using m-cresol instead of sulfuric acid, a temperature of 20°C and a concentration of 0.5% by mass,

[0123] b) from 25 to 40% of recycled carbon fibers having an average length less than or equal to 6 mm before compounding, said recycled carbon fibers being surface coated (sized) with a polyamide, in particular an aliphatic polyamide,

[0124] c) from 0.1 to 5% of at least one additive,

[0125] the sum of components a), b) and c) being equal to 100%.

[0126] In a second embodiment, said composition of the invention is made up of the various elements a, b and c, their sum being equal to 100% by weight defined in the first embodiment and of the three variants with their particular embodiment defined above.

[0127] Whatever the embodiments of the compositions described above, said composition is characterized in that the mechanical properties thereof are at least equivalent to those of the same composition but comprising virgin carbon fibers having an average length less than or equal to 6 mm in place of the recycled carbon fibers before the compounding step, said virgin carbon fibers being surface-coated (sized) with the same polyamide or a polymer other than a polyamide.

[0128] In particular, the resilience as measured by Charpy impact on unnotched bars leU at 23°C of the compositions according to the invention is more than 10% higher than that obtained with virgin carbon fibers sized with a polyamide or with recycled carbon fibers but sized with a polymer other than a polyamide.

[0129] Advantageously, the elongation at break of the compositions according to the invention is more than 10% greater than that obtained with virgin carbon fibers sized with a polyamide or with recycled carbon fibers but sized with a polymer other than a polyamide.

[0130] In one embodiment, the resilience as measured by Charpy impact on unnotched bars leU at 23°C of the compositions according to the invention is more than 10% higher than that obtained with virgin carbon fibers sized with a polyamide or with recycled carbon fibers but sized with a polymer other than a polyamide.

[0131] In another embodiment, the resilience as measured by Charpy impact on unnotched bars leU at 23°C and the elongation at break of the compositions according to the invention are greater than 10% than those obtained with virgin carbon fibers sized with a polyamide or with recycled carbon fibers but sized with a polymer other than a polyamide.

[0132] According to another aspect, the present invention relates to the use of a composition as defined above, for the manufacture of articles obtained by injection chosen from a sports article, in particular a sports shoe, in particular a

[0133]

[0134]

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[0138]

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[0142] ski boot or part of a ski boot or a rigid spiked boot, such as a soccer, rugby or American football boot; a hockey boot or part of a hockey boot, or a running shoe; a golf ball or part of a golf ball, or a stick in the sport of lacrosse; a hockey article such as a helmet; and sporting goods for the protection of the head, shoulders, elbows, hands, knees, back or shin, such as helmets, gloves, shoulder pads, elbow pads, knee pads or shin guards. According to yet another aspect, the present invention relates to the use of a molding composition as defined above, for the manufacture of an article for electronics, for automobiles, for telecom applications or for data exchange, such as for an autonomous vehicle or for applications connected to each other. According to another aspect, the present invention relates to an article obtained by injection molding of a composition as defined above. Examples: The present invention will now be illustrated by the following examples without, however, being limiting of the invention. Preparation of the compositions of the invention and mechanical properties: The compositions in Table I were prepared by melt blending the polymer granules with the carbon fibers and additives. This blending was carried out by compounding on a 26 mm diameter co-rotating twin-screw extruder with a flat temperature profile (T°) at 240°C. The screw speed was 200 rpm and the throughput was 16 kg / h. The introduction of carbon fibers is carried out by lateral force feeding. The polyamide(s) and additives are added during the hopper compounding process main. The compositions were then molded on an injection press at a material temperature of 260°C and a mold temperature of 60°C in the form of dumbbells or bars in order to study the mechanical properties according to the standards below CE 1 CE2 CE3 El PAU (iv m-cresol = 0.9) 67.84 67.84 67.84 67.84 Additives 2.16 2.16 2.16 2.16 Virgin carbon fiber PAN, sized with polyurethane size with a length of 6 mm and a diameter of 30.00 filament = 7 pm Virgin carbon fiber PAN, sized with polyamide sizing with a length of 6 mm and a filament diameter = 7 pm 30.00 Recycled carbon fiber PAN, sized with polyamide sizing with a length of 6 mm and a filament diameter = 7 pm 30 Recycled carbon fiber PAN, sized with polyurethane sizing with a length of 6 mm and a filament diameter = 7 pm 30 Tensile modulus (GPa) ISO 527-1: 2012 17.1 17.3 16.9 18.3 Stress at break MPa 168 175 163 180 Elongation at break % 4 4.2 3.5 4.7 Notched impact according to ISO 179: leA at 23°C, resilience (kJ / m2) 22 23 20 23 Notched impact according to ISO 179: leA at -30°C, resilience (kJ / m2) 14 15 12 15 Unnotched impact leU at 23°C, resilience (kJ / m2) 83 83 80 95 Unnotched impact leU at -30°C, resilience (kJ / m2) 82 83 79 97

[0143] CE: Counterexample

[0144] E: examples of the invention

[0145] The proportions are indicated in mass proportion (%)

[0146] Virgin PAN and recycled PAN carbon fibers with polyurethane or polyamide sizing are marketed for example by Mitsubishi, SGL, ACECA, Teijin, Zoltek or Hexcel.

[0147] PA11: synthesized by the applicant

[0148] The tensile modulus, elongation and breaking stress were measured at 23°C according to ISO 527-1:2012 on a dry sample.

[0149] The machine used is of type INSTRON 5966. The speed of the crosshead is 1 mm / min for the

[0150] measurement of the modulus and 5 mm / min for the breaking stress and the breaking elongation. The

[0151] test conditions are 23°C + / - 2°C, on dry samples.

[0152] The impact resistance was determined according to ISO 179-1:2010 (Charpy impact) on bars of

[0153] dimension 80mm x 10mm x 4mm, notched and unnotched, at a temperature of 23°C + / - 2°C under a relative humidity of 50% + / - 10% or at -30°C + / -2°C under a relative humidity of 50% + / - 10% on dry samples.

[0154] The examples and counterexamples above show that the mechanical properties of compositions based on recycled carbon fibers sized with a polyamide are better than those of compositions based on virgin carbon fibers sized with a polyamide or virgin carbon fibers sized with another polymer.

Claims

Claims

1. A molding composition comprising by weight: a) from 50 to 99% of a semi-crystalline aliphatic polyamide having an inherent viscosity of less than or equal to 1.10, in particular less than or equal to 1.00, in particular less than or equal to 0.95, in particular less than or equal to 0.9, as determined according to ISO 307:2007 but using m-cresol instead of sulfuric acid, a temperature of 20°C and a concentration of 0.5% by mass, b) from 1 to 50% of recycled carbon fibers having an average length of less than or equal to 6 mm before compounding, said recycled carbon fibers being surface-coated (sized) with a polyamide, in particular an aliphatic polyamide, c) from 0 to 5% of at least one additive, the sum of components a), b) and c) being equal to 100%.

2. Molding composition according to claim 1, characterized in that the semi-crystalline aliphatic polyamide (a) is obtained by polycondensation: of at least one C6 to C[8, preferably C9 to Cig, more preferably C10 to C[8, in particular C10 to C12, aminocarboxylic acid, or of at least one C6 to C[8, preferably C9 to C[8, more preferably C10 to C[8, in particular C10 to C12, lactam, or of at least one C4-C36, preferably C6-Ci8, preferably C6-Ci2, more preferably C10-Ci2, diamine Ca with at least one C4-C36, preferably C6-Ci8, preferably C6-Ci2, more preferably C10-Ci2, dicarboxylic acid Cb.

3. Molding composition according to one of claims 1 or 2, characterized in that said polyamide (a) has an average number of carbon atoms per nitrogen atom greater than or equal to 8, in particular greater than or equal to 9, in particular greater than or equal to 10.

4. Molding composition according to claim 3, characterized in that said polyamide (a) is chosen from PA610, PA612, PA1010, PA1012, PA1212, PA11 and PA12, in particular PA1010, PA1012, PA1212, PAU, PA 12, more particularly PA11 and PA 12, in particular PAU.

5. Molding composition according to one of claims 1 to 4, characterized in that the resilience as measured by charpy impact on unnotched bars leU at 23°C of said compositions is greater more than 10% to that obtained with virgin carbon fibers sized with a polyamide or with recycled carbon fibers but sized with a polymer other than a polyamide.

6. Molding composition according to one of claims 1 to 4, characterized in that the resilience as measured by charpy impact on unnotched bars leU at 23°C and the elongation at break of said compositions are greater by more than 10% than those obtained with virgin carbon fibers sized with a polyamide or with recycled carbon fibers but sized with a polymer other than a polyamide.

7. Use of a composition as defined in one of claims 1 to 6, for the manufacture of articles obtained by injection chosen from a sports article, in particular a sports shoe, in particular a ski shoe or a part of a ski shoe or a rigid shoe with studs, such as a soccer, rugby or American football shoe, a hockey shoe or a part of a hockey shoe, or a running shoe, a golf ball or a part of a golf ball, or a stick in the sport of lacrosse, a hockey article such as a helmet and sports articles for the protection of the head, shoulders, elbows, hands, knees, back or shin, such as helmets, gloves, shoulder pads, elbow pads, knee pads or shin guards.

8. Use of a molding composition as defined in one of claims 1 to 6, for the manufacture of an article for electronics, for automobiles, for telecom applications or for data exchange, such as for an autonomous vehicle or for applications connected to each other.

9. Article obtained by injection molding of a composition as defined in one of claims 1 to 6.