Reinforced paek compositions comprising recyclable carbon fibers

Abstract

A method for recycling PEKK-based carbon fiber reinforced polymer composites is provided. Chunks obtained by pulverizing the carbon fiber reinforced PEKK composites are melt mixed with virgin poly(arylene ether ketone) polymer to provide a carbon fiber reinforced poly(arylene ether ketone) composition. Molded articles having good mechanical properties can be prepared from the carbon fiber reinforced poly(arylene ether ketone) composition.

Description

[0001] This application claims priority to U.S. provisional application 63 / 042,035 filed on June 22, 2020 and to European patent application 20186867.6 filed on July 21, 2020, the entire contents of each of these applications are incorporated herein by reference for all purposes. TECHNICAL FIELD

[0002] The present invention relates to a process for the preparation of a composition comprising carbon fibers and a polyaryletherketone polymer. BACKGROUND

[0003] Carbon fiber reinforced polymer composites (CFRP), i.e. fiber reinforced composites using carbon fibers as the main structural component and a polymer (thermoset or thermoplastic) as the matrix component, are lightweight strong materials used to manufacture numerous products. In the last few years, the demand for them has increased, for example to replace many metal parts inside aircraft to reduce weight while maintaining high performance. This results in a large amount of residue generation and scrap product generation. Unlike metals, the waste generated during the manufacturing process of carbon fiber composites and the options for recycling of scrap products are limited. During the forming process of traditional metal parts, the resulting metal slag is recyclable and waste is also minimized. For carbon fiber composites, the options for recycling of offcuts and trimmings waste are limited and mainly disposed in landfills or by incineration.

[0004] These methods lead to an increasing environmental awareness of determining sustainable treatment methods and providing solutions to prevent waste accumulation and respond to the growing demand for raw carbon fibers.

[0005] Therefore, there is a need to determine methods for recycling and reusing waste carbon fiber composites, thus helping to avoid waste disposal problems that can otherwise arise.

[0006] An increasing number of users are beginning to realize the potential of carbon fiber composites, whose polymer matrix is composed of engineering thermoplastic polymers such as poly(aryletherketone) (PAEK) and polyphenylene sulfide (PPS). Thermoplastic polymers offer manufacturers faster processing times, higher toughness and near-infinite shelf life.

[0007] In particular, the present inventors have investigated the possibility of reusing carbon fiber reinforced composites comprising a thermoplastic matrix, in particular a matrix comprising a poly(aryletherketone) polymer.

[0008] Mechanical recycling is one of the methods of recycling of fiber reinforced composites. In general, mechanical recycling is a technique used to reduce the size of waste composites into smaller pieces and then reuse them.

[0009] Mechanical recycling of poly(ether ether ketone) based carbon fiber composites (hereinafter CF / PEEK) has been previously disclosed.

[0010] Li H., Englund K.; "Recycling of carbon fiber-reinforced thermoplastic composite wastes from the aerospace industry", J. Compos. Mater., 51, 1265-1273 (2017) and Ramakrishna S., Tan W.K., Teoh S.H., et al.; "Recycling of carbon fiber / PEEK composites"; Key. Eng. Mater., 137, 1-8 (1997) both disclose a process wherein the process reduces the size of CF / PEEK composite parts using mechanical devices (hammer mill and / or shredder and rotary knife granulator) and then compression molds them into test samples and subjects them to mechanical testing. Both studies show a decrease in the mechanical properties of the parts obtained with recyclable CF / PEEK composites compared to the original composite.

[0011] Schinner G, Brandt J and Richter H.; "Recycling carbon fiber-reinforced thermoplastic composites", J. Thermoplast. Compos. Mater. 9, 239-245 (1996) discloses a process for recycling CF / PEEK composites wherein ground CF / PEEK composites are used to reinforce virgin PEEK injection molding. According to this paper, the injection molded plaques obtained with recyclable CF / PEEK material have comparable properties to an equivalent amount of virgin injection molded carbon fiber filled with PEEK material.

[0012] It has now been found that a poly(aryletherketone) composition comprising a recyclable composite having good mechanical properties can be obtained by recycling a poly(etherketoneketone)-based carbon fiber composite (hereinafter "CF / PEKK"). In particular, it has now been surprisingly found that when using a recyclable CF / PEKK composite, it is possible to obtain a carbon fiber reinforced poly(aryletherketone) composition having better mechanical properties than the poly(aryletherketone) compositions containing recyclable CF / PEEK composites of the prior art. DETAILED DESCRIPTION

[0013] Therefore, a first object of the present application is a process for the preparation of a carbon fiber reinforced poly(aryletherketone) composition by using scraps obtained from a CF / PEKK composite as a source of carbon fibers.

[0014] The expression CF / PEKK composite is used herein to mean a poly(etherketoneketone)-based, PEKK-based carbon fiber composite.

[0015] Therefore, an object of the present application is a process for the preparation of a carbon fiber reinforced poly(aryletherketone) composition, said process comprising:

[0016] - providing scraps of a CF / PEKK composite, and

[0017] - melt-mixing said scraps with at least one poly(aryletherketone) polymer different from the PEKK polymer in the CF / PEKK composite (hereinafter "PAEK polymer"), and optionally at least one polymer different from the PAEK polymer and different from the PEKK polymer in the CF / PEKK composite (hereinafter "polymer (OP)").

[0018] The expression "carbon fiber reinforced poly(aryletherketone) composition" (hereinafter "reinforced PAEK composition") is used to mean a composition comprising one or more polymers selected from the group of poly(aryletherketone) polymers and carbon fibers. The carbon fibers in the poly(aryletherketone) composition are discontinuous short-cut carbon fibers.

[0019] For the purposes of the present application, the term "poly(aryletherketone)" is used interchangeably with the term "PAEK", intended to mean any polymer comprising repeating units of which more than 50 mol% of said repeating units are repeating units comprising an Ar-C(=0)-Ar' group, wherein Ar and Ar', equal to or different from each other, are aromatic groups and mol% is based on the total number of moles of repeating units in the polymer. These repeating units are generally selected from the group consisting of formulae (J-A) to (J-O) hereinafter:

[0020]

[0021]

[0022]

[0023] wherein:

[0024] - each R', equal to or different from each other, is selected from the group consisting of halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine and quaternary ammonium;

[0025] - j' is zero or an integer from 1 to 4.

[0026] In repeating units (J-A) to (J-O), the respective phenylene moieties can independently have 1,2-, 1,4- or 1,3-linkages to other moieties in the repeating unit different from R'. Preferably, the phenylene moieties have 1,3- or 1,4-linkages.

[0027] Preferably, the phenylene moieties have no further substituents than those which make the linkages in the polymer backbone, i.e. j' is preferably zero in each occurrence.

[0028] The poly(aryletherketone) suitable for the process of the present application preferably has an intrinsic viscosity (IV) in the range from about 0.5 to about 1.8 dL / g, measured according to ASTM D2857-95 in concentrated sulfuric acid (minimum 96%) and a concentration of 0.1% at 25°C. The poly(aryletherketone) preferably has a melt viscosity (measured at 400°C, 1000 s -1 of shear rate) from about 0.05 to 0.65 kPa-s.

[0029] Any poly(aryletherketone) polymer different from the PEKK polymer in the CF / PEKK composite can be used in the process.

[0030] Notable examples of suitable poly(aryletherketone)s are, for example, poly(etherketone) (PEK), poly(etheretherketone) (PEEK), poly(etheretherketoneketone) (PEEKK) and poly(etherketoneetherketoneketone) (PEKEKK) polymers.

[0031] In an advantageous embodiment, the poly(aryletherketone) polymer is a poly(etheretherketone) (PEEK), i.e. a homopolymer of repeating unit (J-A) wherein j' = 0 and all phenylene moieties have 1,4-linkages.

[0032] Any PEEK polymer suitable for preparing carbon fiber filler molding compositions can be used. The PEEK polymer preferably has a melt viscosity (at 400°C, 1000 s -1 measured below).

[0033] The poly(arylene ether ketone) polymer can alternatively be selected from PEEK-PEoEK copolymers, i.e. polymers wherein j’ = 0 and the phenylene moieties independently have repeating units of 1,2- and 1,4-linkage (J-A). The PEoEK polymers typically comprise repeating units of the following formulae (A’) and (B’):

[0034]

[0035] Typically, the PEoEK polymer is selected from those polymers as defined above wherein the ratio of the total number of moles of repeating unit (A’) to the total number of moles of repeating unit (B’) ranges from 95 / 5 to 70 / 30, preferably from 90 / 10 to 72 / 28, more preferably between 85 / 15 and 74 / 26, such as a molar ratio of about 95 / 5, about 90 / 10, about 85 / 15, about 80 / 20, about 75 / 25 or about 70 / 30.

[0036] The poly(arylene ether ketone) polymer can also be selected from PEEK-PEDEK copolymers, i.e. polymers comprising repeating units of (J-A) and (J-D) wherein j’ = 0 and all phenylene moieties have 1,4-linkage. The PEEK-PEDEK copolymers typically comprise repeating units of the following formulae (A’) and (C’):

[0037]

[0038] The repeating units (C’) and (A’) are present in the PEDEK-PEEK copolymers in a (C’) / (A’) molar ratio ranging from 55 / 45 to 80 / 20, preferably 60 / 40 to 80 / 20, more preferably from 60 / 40 to 75 / 25.

[0039] In one embodiment of the present application, the pieces of CF / PEKK composite are melt-mixed with one or more PAEK polymers.

[0040] In another embodiment of the present application, the pieces of CF / PEKK composite are melt-mixed with one or more PAEK polymers and one or more other polymers OP.

[0041] Typically, the one or more PAEK polymers are present in an amount greater than the one or more other polymers OP. The combined weight of the PAEK polymers is generally at least 50 wt% of the total weight of the PAEK polymers and the polymer OP.

[0042] The polymer OP can be selected among any polymer that is suitable for melt-mixing with poly(arylene ether ketone) polymers.

[0043] In one aspect of said embodiments, the polymer OP is selected from the group of poly(arylene ether sulfone) polymers (hereinafter referred to as “PAES polymers”). For the purposes of the present invention, the term “poly(arylene ether sulfone)” or “PAES polymer” denotes any polymer whose at least 50 mol% of the repeating units are repeating units of formula (K)

[0044] (R PAES ) based on the total number of moles of repeating units in the polymer:

[0045]

[0046] wherein:

[0047] R, at each location, is independently selected from the group consisting of halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine and quaternary ammonium;

[0048] For each R, h is independently zero or an integer ranging from 1 to 4, and

[0049] T is selected from the group consisting of a bond, a sulfone group [-S(=0) 2- ], and a group -C(R j )(R k )-, wherein R j and R k are the same or different from each other, selected from hydrogen, halogen, alkyl, alkenyl, alkynyl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine and quaternary ammonium.

[0050] T is preferably a bond, a sulfone group or a group -C(Rj)(Rk)-, wherein R j and R k are preferably methyl.

[0051] Notable examples of suitable poly(arylene ether sulfone) are, for example, a polysulfone (PSU), a polyphenylsulfone (PPSU) or a polyethersulfone (PES) polymer.

[0052] The term poly(sulfone) (PSU) denotes any polymer comprising at least 50 mol% of recurring units of formula (L), the mol% being based on the total number of moles in the polymer:

[0053]

[0054] The term poly(phenylsulfone) (PPSU) denotes any polymer comprising at least 50 mol% of recurring units of formula (M), the mol% being based on the total number of moles of recurring units in the polymer:

[0055]

[0056] The term poly(ether sulfone) (PES) denotes any polymer comprising at least 50 mol% of recurring units of formula (O), the mol% being based on the total number of moles of recurring units in the polymer:

[0057]

[0058] In one aspect of the application, the fragments of CF / PEKK composite are melt-mixed with a composition comprising one or more PAEK polymers, poly(phenylsulfone) (PPSU) and poly(ether sulfone) (PES).

[0059] The composition preferably comprises PEEK, poly(phenylsulfone) (PPSU) and poly(ether sulfone) (PES). The composition can comprise 50 to 60 wt% of PEEK, 30 to 40 wt% of poly(ether sulfone) (PES) and 5 to 10 wt% of poly(phenylsulfone) (PPSU), the wt% being based on the total weight of the composition.

[0060] For the avoidance of doubt, the term “poly(ether ketone ketone)” or “PEKK” is intended to denote any polymer comprising at least 50% by moles of recurring units (J-B) in which j’ = 0 and the corresponding phenylene moieties can independently have 1,2-, 1,4- or 1,3-linkages, preferably said phenylene moieties have 1,3- or 1,4-linkages.

[0061] PEKK polymers can be characterized by the ratio between 1,3- and 1,4-phenylene linkages in the polymer. In particular, their difference can be the ratio between recurring units of the following formulae (M’) and (P’):

[0062]

[0063] Typically, the PEKK polymer in the CF / PEKK composite is selected from those PEKK polymers as defined above, wherein the ratio of the total number of moles of repeating units (P') to the total number of moles of repeating units (M') ("(P') / (M') ratio" or "T / I ratio") ranges from 55 / 45 to 75 / 25, preferably from 60 / 40 to 80 / 20, more preferably from 62 / 38 to 75 / 25.

[0064] When the poly(arylene ether ketone) is a PEKK polymer, it is generally characterized by a different T / I ratio relative to the PEKK polymer in the CF / PEKK composite.

[0065] In a first step of the present process, a scrap of CF / PEKK composite is provided.

[0066] The scrap of CF / PEKK composite is typically obtained by shredding an article made of CF / PEKK composite.

[0067] The present process thus comprises the following steps:

[0068] - providing an article made of CF / PEKK composite;

[0069] - shredding said article to obtain a scrap of CF / PEKK composite; and

[0070] - melt-mixing said scrap with at least one poly(arylene ether ketone) polymer different from the PEKK in the CF / PEKK composite.

[0071] The article made of CF / PEKK composite can be a scrap of the composite manufacturing process or a scrap of unitap production, such as offcuts and trimmings or products not meeting thickness specifications, to name a few.

[0072] In one embodiment of the present process, the article consists of offcut or offcut scrap generated during the manufacturing process of the CF / PEKK composite.

[0073] In a preferred aspect of said embodiment, the CF / PEKK composite comprises a unidirectional continuous fiber reinforced tape made by a melt-impregnation process. The melt-impregnation process generally comprises pulling a plurality of continuous filaments through a molten precursor composition comprising a polymer. The precursor composition can additionally comprise specific ingredients that facilitate impregnation, such as plasticizers and processing aids. The melt-impregnation process includes direct melt and aromatic polymer composite ("APC") processes, such as the process described in EP 102158.

[0074] Advantageously, the CF / PEKK composite is obtained by a melt-impregnation process in the presence of diphenyl sulfone as a plasticizer. The residual amount of diphenyl sulfone in the CF / PEKK composite is from 0.01 wt% to 1.00 wt% relative to the total weight of the CF / PEKK composite. The amount of diphenyl sulfone can be from 0.03 wt% to 0.90 wt%, even from 0.04 to 0.85 wt%, preferably from 0.04 to 0.80 wt%.

[0075] Without being bound by theory, it is believed that the presence of diphenyl sulfone in the CF / PEKK chips improves the bonding of the carbon fibers and the poly(arylene ether ketone) polymer in the composition.

[0076] In another embodiment, the composite comprises unidirectional continuous fiber reinforced tapes made by a pulp process. Exemplary pulp processes can be found for example in US 4792481.

[0077] The CF / PEKK composite typically comprises from 20 to 80 wt%, more typically from 40 to 80 wt% of carbon fibers. The CF / PEKK composite typically comprises from 80 to 20 wt%, more typically 60 to 20 wt% of PEKK polymer relative to the weight of the composite.

[0078] The step of shredding (i.e. cutting or chopping) the CF / PEKK composite article into chips is typically performed using a mechanical device. Any mechanical device known in the art can be used, such as blades, for example die-cutting blades or roller blades, die-cutting lattices, shredders or any other suitable device. A laser can also be used to shred the CF / PEKK article into chips.

[0079] The length of the chips into which the CF / PEKK composite article is cut is preferably in the range from 3 to 50 mm, in particular in the range from 5 to 20 mm. The chip length should also be chosen to fit the feeding capacity of the machine used to mix the chips of CF / PEKK composite with the at least one poly(arylene ether ketone) polymer.

[0080] When the chips of CF / PEKK composite are melt-mixed with the at least one poly(arylene ether ketone) polymer, the individual chips disintegrate into individual fibers which are then mixed into the polymer melt. The properties of the resulting reinforced PAEK composition correspond to the properties of a short-fiber reinforced polymer.

[0081] Any known melt-mixing process suitable for the preparation of thermoplastic compositions can be used to manufacture the reinforced PAEK composition. Such processes are typically carried out by heating the thermoplastic polymer above the melting temperature of the polymer thereby forming a melt of the thermoplastic polymer.

[0082] The process for preparing the reinforced PAEK composition can be carried out in a melt mixing device. Any melt mixing device known to the person skilled in the art for the preparation of polymer compositions by melt mixing can be used. Suitable melt mixing devices are, for example, a kneader, a Banbury mixer, a single screw extruder, a twin screw extruder and an injection molding machine.

[0083] The addition of the chips to the polymer melt provides a more homogeneous mixing of the melt with the chips and thus a more homogeneous distribution of the resulting individual fibers in the polymer melt.

[0084] When melt mixing is carried out using an extruder, a multi-screw extruder such as a twin screw extruder can be used. The use of twin screw extruders can be advantageous as they have in particular a better mixing effect compared to single screw extruders.

[0085] The proportion of chips of the CF / PEKK composite melt-mixed with the at least one poly(arylene ether ketone) and optionally at least one other polymer OP is such that the amount of carbon fibers in the final reinforced PAEK composition is from 5 to 60 wt.-% relative to the total weight of the composition. Typically, the proportion of chips is such that the amount of carbon fibers in the reinforced PAEK composition is from 5 to 60 wt.-%, even from 5 to 50 wt.-%, preferably from 10 to 50 wt.-%, even from 10 to 45 wt.-%, relative to the total weight of the composition.

[0086] The reinforced PAEK composition obtained by the process of the present application is preferably in the form of a pelletized material. However, in addition to the pelletized material, the reinforced PAEK composition can also be in the form of a layer or an extrudate. When the reinforced PAEK composition is in the form of a pellet, the pellet is produced in the usual manner by forcing the polymer melt through a pelletizing die and short-cutting into pellets by means of a pelletizing knife.

[0087] To do this, one possible method is to first produce a polymer extrudate, cool it and then short-cut into pellets. Alternatively and conventionally, the polymer forced through the pelletizing die is subjected to face cutting directly. This cutting can be carried out in air, in which case the cut pellets preferably fall into a cooling liquid and solidify. Water is one example of a suitable cooling liquid. Alternatively, underwater pelletizing is also possible, in which case the polymer melt is forced through the pelletizing die into a cooling liquid and directly face-cut into pellets. In any case, the pellets are output together with the cooling liquid, then separated from the cooling liquid and dried.

[0088] The length of the carbon fibers in the reinforced PAEK composition is first dependent on the shear of the fibers in the melt mixing machine and secondly on the size of the pellet-like material cut out of the polymer melt. The maximum fiber length corresponds to the maximum longitudinal extent of a single pellet. If longer fibers are required, not only chips with a larger rim length need to be cut, but also larger pellets need to be produced. The pellet is preferably cylindrical and its maximum extent is typically the height of the cylinder. However, alternatively, a larger diameter and a lower height can also be chosen. However, since the fibers are aligned in an essentially parallel alignment with respect to the axis of the holes in the die of the pelletizer, typically the axial extent of the pellet determines the maximum achievable fiber length.

[0089] Typically, the average length of the carbon fibers in the reinforced PAEK composition ranges from 0.05 to 10 mm, from 0.05 to 6 mm, even from 0.1 to 5 mm, more typically from 0.1 to 3 mm.

[0090] The reinforced PAEK composition can be further processed into articles using any suitable melt processing technique including, but not limited to, extrusion molding, injection molding, and compression molding.

[0091] According to an exemplary embodiment, the reinforced PAEK composition obtained by the process of the present application, wherein the chips of the CF / PEKK composite are melt-mixed with one or more PAEK polymers, can be characterized by at least one of the following properties:

[0092] - a tensile strength equal to or greater than 255 GPa measured according to ASTM D638 (test speed: 0.5 cm / min) on ASTM Type I dog bone test specimens (length 16.5 cm, width 1.3 cm, thickness 0.32 cm);

[0093] - a flexural strength equal to or greater than 370 MPa measured according to ASTM D790 (test speed: 0.13 cm / min, span 5.1 cm) on bars (length 12.7 cm, width 1.3 cm and thickness 0.32 cm)

[0094] According to a further exemplary example, the reinforced PAEK composition obtained by the process of the present application, wherein the chips of the CF / PEKK composite are melt-mixed with a composition comprising PEEK, polyphenylsulfone (PPSU) and polyethersulfone (PES), can be characterized by at least one of the following properties:

[0095] - a tensile strength equal to or greater than 160 GPa measured according to ASTM D638 (test speed: 0.5 cm / min) on ASTM Type I dog bone test specimens (length 16.5 cm, width 1.3 cm, thickness 0.32 cm);

[0096] - Flexural strength equal to or greater than 235 MPa measured on a bar (12.7 cm long, 1.3 cm wide and 0.32 cm thick) according to ASTM D790 (test speed: 0.13 cm / min, span 5.1 cm).

[0097] Therefore, this invention allows for the production of articles made of reinforced PAEK materials using waste CF / PEKK composite materials as raw materials. The reinforced PAEK composition is characterized by good mechanical properties, making it suitable for manufacturing high-value-added articles.

[0098] Reinforced PAEK compositions can be used industrially to manufacture a variety of finished products. Therefore, another object of the present invention is an article made of or containing a reinforced PAEK composition. Articles that can be made from reinforced PAEK compositions are particularly those requiring high levels of strength, stiffness, and toughness.

[0099] Advantageously, the articles can be injection-pressed or extruded molded articles.

[0100] Non-limiting examples of articles include valve seats / seals, pump wear rings, gears and vanes or medical device fixtures, turbines and / or turbine housings for home appliances.

[0101] If any patent, patent application, or publication incorporated herein by reference conflicts with the description of this application to the extent that it may lead to ambiguity in terminology, then this description shall take precedence.

[0102] The invention will now be described in more detail with reference to the following examples, which are merely illustrative and do not limit the scope of the invention.

[0103] Example

[0104] Material

[0105] CF / PEKK: APC (PEKK) carbon prepreg, commercially available from Cytec Engineered Materials / Cytec Industries Inc., Woodland Park, New Jersey; containing 64 to 67 wt% carbon fiber. AS4D and 33 to 36 wt% PEKK resin (T / I ratio = 72:28; Tg = 155℃, Tm = 335℃)

[0106] CF / PEEK: APC-2 (PEEK), commercially available from Cytec Engineering Materials / Cytec Industries, Inc., Woodland Park, New Jersey; contains:

[0107] KT880: KT-880P PEEK (commercially available from Solvay Specialty Polymers USA, Inc.), grade with a melt viscosity range of 0.12-0.18 kPa-s (measured by capillary rheometer at a temperature of 400 °C and a shear rate of 1000 s -1

[0108] KT890: KT-890P PEEK (commercially available from Solvay Specialty Polymers USA, Inc.), grade with a melt viscosity range of 0.07 to 0.11 kPa-s (measured by capillary rheometer at a temperature of 400 °C and a shear rate of 1000 s -1

[0109] PPSU: R 5900 PPSU [MFR (365 °C / 5 kg) in the range from 26 to 36 g / 10 min] is a polyphenylsulfone (PPSU) homopolymer from Solvay Specialty Polymers USA, Inc.

[0110] PES: A-702 NT PES [MFR (380 °C / 2.16 kg) in the range from 65 to 85 g / 10 min] is a polyethersulfone (PESU) homopolymer from Solvay Specialty Polymers USA, Inc.

[0111] Chopped CF: Torayca® C-30S006 APS from SGL Carbon Fibers Ltd. C30S006 APS

[0112] PEPQ: PEPQ is an aromatic organic phosphonate melt heat stabilizer available from Clariant

[0113] Zinc oxide: grade Z-CAP® 3000 from Lanxess Corporation

[0114] General Procedure

[0115] The strips of CF / PEKK or CF / PEEK material were shredded into pieces 5 to 7 mm long and 3 to 7 mm wide using a shredder.

[0116] The pieces were melt-mixed with virgin PEEK resin (KT880 or KT890) or with a composition comprising PEEK (KT890), PPSU, and PES using a ZSK-26 Coperion twin-screw extruder (12 barrel segments, 26 mm diameter, L / D ratio of 48) and injection molded into test bars for further testing.​​

[0117] Comparative samples were prepared by mixing the same virgin PEEK resin or PEEK, PPSU and PES compositions with standard short chopped carbon fibers to obtain compositions containing the same wt% of carbon fibers, which were then injection molded into ASTM test bars.

[0118] Tensile properties were measured according to ASTM D638 (test speed: 0.5 cm / min) on ASTM Type I dog bone test samples (16.5 cm long, 1.3 cm wide, 0.32 cm thick).

[0119] Flexural properties were measured according to ASTM D790 (test speed: 0.13 cm / min, span 5.1 cm) on bars (12.7 cm long, 1.3 cm wide and 0.32 cm thick).

[0120] Notched Izod impact resistance and unnotched Izod impact resistance were determined according to ASTM test methods D256 and D4812, respectively, using injection molded plaques (10.16 cm x 10.16 cm and 0.32 cm thick). The results of the tests are reported in Table 1.

[0121] The data in Table 1 show that the reinforced PAEK compositions obtained using the scrap of CF / PEKK composites as a source of carbon fibers (Examples 1, 2 and 3) have good mechanical properties compared to the reinforced PAEK compositions obtained from virgin PAEK and virgin carbon fibers (Comparative Example 1, and Comparative Examples 3 and 4).

[0122] The data also surprisingly show that the tensile and flexural strength of the reinforced PAEK compositions obtained using the scrap of CF / PEKK composites (Example 1) are higher than those of the PAEK compositions obtained using the scrap of CF / PEEK composites (Comparative Example 2).

[0123] Good mechanical properties can also be obtained when the reinforced PAEK compositions comprise polymers other than PAEK polymers, in particular PES and PPSU polymers. The reinforced composition of Example 5 exhibits higher tensile and flexural strength and higher impact strength relative to the composition of Comparative Example 5, which was prepared using virgin carbon fibers.

[0124] Table 1

[0125]

[0126]

Claims

1. A method for preparing a carbon fiber reinforced poly(aryl ether ketone) composition, the method comprising: - Provide fragments of CF / PEKK composite material, the CF / PEKK composite material comprising unidirectional fibers; and - The fragments are melt-mixed with at least one poly(aryletherketone) polymer that is different from PEKK in the CF / PEKK composite material.

2. The method of claim 1, wherein the CF / PEKK composite material comprises a unidirectional continuous fiber reinforced tape made by a melt impregnation process or a unidirectional continuous fiber reinforced tape made by a slurry process.

3. The method of claim 1, further comprising the following steps: - Items made from CF / PEKK composite material are available; - Crush the item to obtain fragments of the CF / PEKK composite material; and - The fragments are melt-mixed with at least one poly(aryletherketone) polymer that is different from PEKK in the CF / PEKK composite material.

4. The method as described in any of the preceding claims, wherein, The CF / PEKK composite contains diphenyl sulfone ranging from 0.01 wt% to 1.00 wt% relative to the total weight of the CF / PEKK composite.

5. The method as described in any one of the preceding claims, wherein, The amount of fragments of the CF / PEKK composite material melt-mixed with the at least one poly(aryletherketone) is such that the amount of carbon fiber in the carbon fiber reinforced poly(aryletherketone) composition is from 5 to 60 wt% relative to the total weight of the composition.

6. The method as described in any of the preceding claims, wherein, Melt mixing takes place in an extruder.

7. The method as described in any of the preceding claims, wherein, Mechanical devices are used to crush the articles made of the CF / PEKK composite material into fragments.

8. The method as described in any of the preceding claims, wherein, At least one of the poly(aryletherketone) is poly(etheretherketone).

9. The method of claim 8, wherein, This poly(ether ether ketone) has a melt viscosity from about 0.05 to 0.50 kPa-s (at 400°C, 1000 s). -1 (Measured below).

10. The method as described in any of the preceding claims, wherein, These CF / PEKK composite fragments are melt-mixed with at least one poly(aryletherketone) and at least one polymer that is different from the at least one poly(aryletherketone) polymer and different from the PEKK polymer in the CF / PEKK composite.

11. The method of claim 10, wherein, The polymer that is different from the poly(aryletherketone) polymer and different from the PEKK polymer in the CF / PEKK composite material is selected from the group consisting of poly(arylethersulfone) polymers, preferably from the group consisting of polysulfone (PSU), polyphenylsulfone (PPSU) or polyethersulfone (PES) polymers.

12. The method of any one of claims 1 to 11, further comprising the step of molding the carbon fiber reinforced poly(aryletherketone) composition into an article.

13. The method as described in any of the preceding claims, wherein, The carbon fiber reinforced poly(aryl ether ketone) composition is in granular form.

14. A carbon fiber reinforced poly(aryletherketone) composition obtainable by the method of any one of claims 1 to 11, comprising PEKK, at least one poly(aryletherketone) different from said PEKK, and carbon fibers from 10 to 50 wt% relative to the total weight of the composition.

15. The carbon fiber reinforced poly(aryl ether ketone) composition of claim 14, wherein: -The composition in which fragments of CF / PEKK composite material are melt-mixed with one or more poly(aryletherketone) polymers is characterized by at least one of the following properties: - Tensile strength equal to or greater than 255 GPa measured on an ASTM Type I dog bone test specimen (16.5 cm long, 1.3 cm wide, and 0.32 cm thick) according to ASTM D638 (test speed: 0.5 cm / min). -According to ASTM D790 (Test speed: Flexural strength equal to or greater than 370 MPa, measured on a bar (12.7 cm long, 1.3 cm wide, and 0.32 cm thick) at a speed of 0.13 cm / min and a span of 5.1 cm; or -The composition wherein fragments of the CF / PEKK composite material are melt-mixed with a composition comprising PEEK, polyphenylsulfone (PPSU) and polyethersulfone (PES) is characterized by at least one of the following properties: - Tensile strength equal to or greater than 160 GPa measured on an ASTM Type I dog bone test specimen (16.5 cm long, 1.3 cm wide, and 0.32 cm thick) according to ASTM D638 (test speed: 0.5 cm / min). -According to ASTM D790 (Test speed: The flexural strength equal to or greater than 235 MPa measured on a bar (12.7 cm long, 1.3 cm wide and 0.32 cm thick) at a speed of 0.13 cm / min and a span of 5.1 cm.

16. An article comprising the carbon fiber reinforced composition as described in claim 14 or 15.

Images