Composite compositions comprising aramid copolymer particles and thermoplastic engineering polymers and articles containing same

Abstract

A composite composition, a process for making the same, and an article comprising the same, wherein the composition comprises 3 to 30 parts by weight of particles comprising an aramid copolymer containing imidazole groups and up to 97 parts by weight of a thermoplastic engineering polymer, the particles being uniformly dispersed in the thermoplastic engineering polymer and reducing the wear rate of the thermoplastic engineering polymer by at least 25 percent.

Description

[Technical Field]

[0001] The present invention is a composite composition comprising solid polymer particles dispersed in an engineering polymer, wherein the combination of the dispersed solid material and the engineering polymer has unexpected mechanical properties. The solid polymer particles can be polymer crumbs or powder-like particles or flocs. [Background technology]

[0002] Articles made from engineering polymers in the molten state are highly valued for their ease and flexibility of manufacture. Such articles can be in the form of injection-molded parts or 3D-printed or additively manufactured parts, such as by fused deposition modeling (FDM), stereolithography (SLA), or selective laser sintering (SLS). Such parts can be, for example, thin-walled parts for use in the automotive and / or aerospace industries or large industrial parts. Any improvements in compositions containing such engineering polymers that add additional product features or improved performance are desirable. Summary of the Invention [Means for solving the problem]

[0003] The present invention provides a) 3 to 30 parts by weight of particles containing an aramid copolymer containing imidazole groups; b) up to 97 parts by weight of a thermoplastic engineering polymer; wherein the particles are uniformly dispersed in a thermoplastic engineering polymer and reduce the wear rate of the thermoplastic engineering polymer by at least 25 percent. The present invention further relates to an article comprising the composite composition.

[0004] The present invention provides a process for producing a composite composition, comprising: a) polymerizing monomers to form an aramid copolymer comprising imidazole groups, the monomers comprising at least one aromatic diacid, at least one aromatic diamine, and one imidazole diamine; b) crushing and isolating the aramid copolymer containing imidazole groups in the form of polymer crumbs of a desired particle size, comprising the aramid copolymer containing imidazole groups; c) optionally further grinding or milling the polymer crumbs to form particles of a desired particle size comprising aramid copolymers containing imidazole groups; d) combining and mixing 3 to 30 parts by weight of the particles with up to 97 parts by weight of a thermoplastic engineering polymer to form a composite composition; The present invention also relates to a process comprising: [Brief explanation of the drawings]

[0005] [Figure 1] 1 is a photograph at 30x magnification of raw polymer particles, generally 1 mm or larger in size, comprising aramid copolymers containing imidazole groups, which are dried, coarsely ground polymer crumbs obtained from a polymerization step and isolated. [Figure 2] 1 is a photograph at 30x magnification of ground particles generally less than 1 mm in size and comprising aramid copolymers containing imidazole groups, referred to herein as "dry extruder" particles, produced from raw polymer particles that are further reduced in size in a twin-screw extruder in a dry state, i.e., particles having less than 10 weight percent moisture. [Figure 3] Photographs at magnification levels of 30x and 100x, respectively, of the same ground particles, generally less than 1 mm in size and comprising aramid copolymers containing imidazole groups, referred to herein as "wet extruder" particles, made from water-wet crumbs from a polymerization that is reduced in size only once in a twin-screw extruder to the desired particle size. [Figure 4]Photographs at magnification levels of 30x and 100x, respectively, of the same ground particles, generally less than 1 mm in size and comprising aramid copolymers containing imidazole groups, referred to herein as "wet extruder" particles, made from water-wet crumbs from a polymerization that is reduced in size only once in a twin-screw extruder to the desired particle size. DETAILED DESCRIPTION OF THE INVENTION

[0006] The present invention relates to composite compositions and articles made therefrom containing a blend of a thermoplastic engineering polymer and aramid copolymer particles, where the aramid copolymer contains imidazole groups in the copolymer chain. Preferably, the particles are uniformly dispersed in the thermoplastic engineering polymer. By uniformly dispersed, we mean that the particles are preferably uniformly distributed in the thermoplastic engineering polymer, preferably in a random manner that can provide uniform mechanical properties to any article made from the composite composition.

[0007] composite composition Specifically, the composite composition includes 3 to 30 parts by weight of particles comprising an aramid copolymer containing imidazole groups. These solid materials are uniformly dispersed in up to 97 parts by weight of a thermoplastic engineering polymer in the composition. When only particles and a thermoplastic engineering polymer are present, the thermoplastic engineering polymer is used in an amount of 3 to 97 parts by weight in the composition. The resulting composition reduces the wear rate of the thermoplastic engineering polymer by at least 25 percent (compared to the wear rate of the thermoplastic engineering polymer alone), thereby increasing the wear resistance of the thermoplastic engineering polymer. In some embodiments, the composite composition includes 5 to 25 parts by weight of particles comprising an aramid copolymer containing imidazole groups and 75 to 95 parts by weight of the thermoplastic engineering polymer. In some embodiments, the addition of particles comprising an aramid copolymer containing imidazole groups reduces the wear rate of the thermoplastic engineering copolymer by at least 45 percent (compared to the wear rate of the thermoplastic engineering polymer alone). In some embodiments, the addition of particles comprising an aramid copolymer containing imidazole groups reduces the wear rate of the thermoplastic engineering copolymer by at least 80 percent when compared to the wear rate of the thermoplastic engineering polymer alone.

[0008] The wear rate of articles including the composite composition is believed to be most improved in applications that mimic high-pressure-velocity wear, as demonstrated by the Thrust Washer (TW) test presented herein, where the addition of particles including an aramid copolymer containing imidazole groups can reduce the wear rate of the thermoplastic engineering copolymer by at least 75 percent, preferably at least 80 percent, and most preferably at least 85 percent or more, when compared to the wear rate of the thermoplastic engineering polymer alone.

[0009] However, the wear rate of articles including the composite composition also shows improvement in applications that mimic low pressure-velocity wear, as shown by the 3-pad washer (3PW) test presented herein, where the addition of particles including an aramid copolymer containing imidazole groups can reduce the wear rate of the thermoplastic engineering copolymer by at least 45 percent, preferably at least 60 percent, even more preferably at least 80 percent or more, and most preferably at least 85 percent or more, when compared to the wear rate of the thermoplastic engineering polymer alone.

[0010] Adhesive properties In addition to improved wear properties, it has been found that aramid copolymers containing imidazole groups have unexpectedly superior adhesion to thermoplastic engineering polymers such as PEEK compared to para-aramid homopolymers such as poly(paraphenylene terephthalamide). This superior adhesion is believed to be in addition to the surprisingly improved wear properties and other properties that aramid copolymers containing imidazole groups can provide to articles.

[0011] One way to characterize improved adhesive properties between materials is found using DIN SPEC 19289:2022-08 "Fiber-reinforced composites—Measurement of Interfacial Shear Strength by means of a Micromechanical Single-Fiber Pull-Out Test," in which a fiber of one material is embedded in a matrix of another material, and then the force required to pull the fiber out of the matrix is ​​measured. (As used herein, the terms "fiber," "fiber," and "filament" are used interchangeably.) This European standard specifies the "apparent interfacial shear strength" (τ ) in MPa. app) is defined as the maximum force normalized to the contact area between the fiber and the solidified matrix, where the maximum force is the maximum force value that occurs just before complete detachment of the fiber from the matrix during pull-out. Furthermore, the "local interfacial shear strength" (τ d ) is defined as the peel force related to the interfacial contact area between the fiber and the solidified matrix without the effect of friction between the fiber and the matrix, where the peel force is the force at which the fiber initiates peeling from the solidified matrix. Additionally, the "critical interfacial energy release rate" (G) in Joules / square meter is also defined. ic ) is defined as the interfacial toughness, taking into account the deformation of the fiber and matrix during pull-out. For the purposes of measuring adhesive properties herein, the fiber material is an aramid copolymer containing imidazole groups, and the matrix material is a thermoplastic engineering polymer.

[0012] In many cases, the "local interfacial shear strength" (τ d ) is believed to be the best measure of adhesion between the polymer of the fiber material and the polymer of the solidified matrix material because it is the peel force without the effect of friction between the fiber and the matrix material. However, all of these specified properties describe the adhesion between the fiber and the matrix material.

[0013] Adhesion between a fiber material that is an aramid copolymer containing imidazole groups and an engineering polymer matrix material using DIN SPEC 19289:2022-08 is directly applicable when the particles of the aramid copolymer containing imidazole groups are in the form of floc. In addition, the particles of the aramid copolymer containing imidazole groups in the form of floc may include a surface or spin "finish." Such finishes are well known to be oils, waxes, or other materials used as fiber processing aids to reduce damage to fibers. Fibers of the aramid copolymer containing imidazole groups further having a surface finish have a higher adhesion strength than the same fiber material without the finish, i.e., the fiber with any surface finish removed. d The increased "local interfacial shear strength" (τd It is believed that the finish may help the matrix polymer better wet the surface of the fiber for better contact.

[0014] Additionally, adhesion between unfinished fiber materials, i.e., adhesion between aramid copolymers containing imidazole groups and engineering polymer matrix materials, using DIN SPEC 19289:2022-08 is believed to be directly applicable when particles of aramid copolymers containing imidazole groups are in the form of raw polymer or ground polymer. Therefore, even though the polymer materials may be in various forms, the adhesion properties of polymer particles to various thermoplastic engineering polymers can be measured by first making filaments of the polymer material, ensuring that no finish is present, then embedding the unfinished filaments in a matrix of the thermoplastic engineering polymer, and subsequently drawing out the filaments, all according to the standard DIN SPEC 19289:2022-08.

[0015] In some embodiments, the "local interfacial shear strength" (τ d ) is the "local interfacial shear strength" (τ d In some embodiments, the "local interfacial shear strength" (τ ) between particles of the aramid copolymer containing imidazole groups and the engineering polymer is greater than τ . d ) is the "local interfacial shear strength" (τ d In some preferred embodiments, the "local interfacial shear strength" (τ ) between particles of the aramid copolymer containing imidazole groups and the engineering polymer is at least 9 percent greater than the "local interfacial shear strength" (τ ) d) is the "local interfacial shear strength" (τ d ) is at least 35 percent greater than PPD-T. In some embodiments, the improvement in local interfacial shear strength over PPD-T using particles of aramid copolymer containing imidazole groups is in the range of 25 to 125 percent.

[0016] In some embodiments, the local interfacial shear strength (τ d ) is equal to or greater than 72 MPa and can range up to or greater than 100 MPa.

[0017] Thermoplastic Engineering Polymers "Thermoplastic engineering polymer" means a polymer that is useful as the sole, primary, or majority polymeric material of construction of a polymer part or component of a device. Additionally, as used herein, "thermoplastic" has its conventional definition in that an engineering polymer in solid form can be heated to a liquid state and then cooled back to a solid state, and this cycle can be repeated with little change in the melting point of the copolymer. Thermoplastic engineering polymers often contain aromatic rings that can be easily substituted or modified as substituents or as part of the primer backbone to provide additional functionality for specific applications.

[0018] Generally, engineering polymers are desirable in articles that can be used at high temperatures, and one measure is the temperature of deflection under load, as measured, for example, according to ASTM D648-07, "Standard Test Method for Deflection Temperature of Plastics Under Flexural Load in the Edgewise Position" (which corresponds to ISO 75). This test measures the temperature at which deformation occurs under a specific load, known as the heat distortion temperature (HDT). Typically, the HDT can be measured at a load value of 1820 kPa, commonly referred to as 1.8 MPa (264 psi). In some preferred embodiments, preferred thermoplastic engineering polymers used in composite compositions have an unfilled or "neat" HDT of 100°C or greater at 1.8 MPa. Representative heat distortion temperatures for certain illustrative thermoplastic engineering polymers are shown in Table 1.

[0019] [Table 1]

[0020] In some embodiments, the thermoplastic engineering polymer of the composite composition preferably comprises a polyaryletherketone (PAEK), which in some embodiments is a poly(etherketone) (PEK), a poly(etheretherketone) (PEEK), a poly(etherketoneketone) (PEKK), or a mixture thereof. In some preferred embodiments, the thermoplastic engineering polymer is or comprises a poly(etheretherketone) (PEEK).

[0021] In some embodiments, the thermoplastic engineering polymer of the composite composition comprises polyamide (PA), polyamide-imide (PAI), polyethersulfone (PES), polyether-imide (PEI), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyoxymethylene (POM), acetal copolymer (AC), polycarbonate (PC), or a mixture thereof. As used herein, "liquid crystal polyester" (LCP) refers to a polyester polymer that is anisotropic when tested using the TOT test or any reasonable modification thereof, as described in U.S. Pat. No. 4,118,372. One preferred form of LCP is "fully aromatic," i.e., all of the groups on the polymer backbone are aromatic (except for linking groups such as ester groups), although non-aromatic side groups may be present. LCPs useful as thermoplastic materials in the present invention have melting points of up to 350°C. Melting points are measured according to test method ASTM D3418. The melting point is taken as the maximum of the melting endotherm and is measured on the second heat at a heating rate of 10° C. / min. If more than one melting point is present, the melting point of the polymer is taken as the melting point maximum.

[0022] Aramid copolymer containing imidazole groups The term "polymer," as used herein, means a material prepared by polymerizing monomers, end-functionalized oligomers, and / or end-functionalized polymers, whether of the same or different types. The term aramid, as used herein, means an aromatic polyamide in which at least 85% of the amide (-CONH-) linkages are attached directly to two aromatic rings.

[0023] The term "aramid copolymer containing imidazole groups," as used herein, refers to a copolymer prepared from an aromatic diacid and a diamine, wherein at least two different diamines are present: an aromatic diamine and an imidazole diamine. The two different diamines can be polymerized with stoichiometric amounts of one or more aromatic diacids.

[0024] Among aromatic diacids, para-oriented aromatic diacids are preferred, and the most preferred para-oriented aromatic diacid is terephthaloyl dichloride.Similarly, among aromatic diamines, para-oriented aromatic diamines are preferred, and the preferred para-oriented aromatic diamine is paraphenylenediamine.

[0025] "Imidazole diamine" refers to a diamine having at least one imidazole group. Preferably, the imidazole diamine is benzimidazole. In some preferred embodiments, the imidazole diamine is 5(6)-amino-2-(p-aminophenyl)benzimidazole (DAPBI). In some preferred embodiments, the aramid copolymer is prepared by polymerizing the monomer 5(6)-amino-2-(p-aminophenyl)benzimidazole, an aromatic diamine, and an aromatic diacid chloride. In some most preferred embodiments, the aramid copolymer is prepared by polymerizing the monomer 5(6)-amino-2-(p-aminophenyl)benzimidazole, paraphenylenediamine, and terephthaloyl dichloride.

[0026] In some embodiments, the molar ratio of the imidazole diamine, such as 5(6)-amino-2-(p-aminophenyl)benzimidazole, to the aromatic diamine is 50 / 50 to 80 / 20. In some particular embodiments, the aramid copolymer containing imidazole groups comprises residues of 5(6)-amino-2-(p-aminophenyl)benzimidazole and residues of paraphenylenediamine, and the molar ratio of the residues of 5(6)-amino-2-(p-aminophenyl)benzimidazole to the residues of paraphenylenediamine is 50 / 50 to 80 / 20. In some particular embodiments, the aramid copolymer containing imidazole groups comprises residues of 5(6)-amino-2-(p-aminophenyl)benzimidazole and residues of paraphenylenediamine, wherein the molar ratio of residues of (6)-amino-2-(p-aminophenyl)benzimidazole to residues of paraphenylenediamine is from 50 / 50 to 70 / 30. In still other embodiments, the imidazole diamine, such as 5(6)-amino-2-(p-aminophenyl)benzimidazole, is 50 mole percent or more of the total moles of imidazole diamine and aromatic diamine present.

[0027] As used herein, "stoichiometric amount" refers to the amount of a component theoretically required to react with all of the reactive groups of a second component. For example, "stoichiometric amount" refers to the number of moles of terephthaloyl dichloride required to react with substantially all of the amine groups of an amine component. The term "stoichiometric amount" is understood by those skilled in the art to refer to an amount typically within 10% of the theoretical amount. For example, the stoichiometric amount of terephthaloyl dichloride used in a polymerization reaction may be 90-110% of the amount of terephthaloyl dichloride theoretically required to react with all of the amine groups.

[0028] In some embodiments, all of the monomers can be combined and reacted together to form a polymer. In some embodiments, a monomer or varying amounts of a monomer can be reacted sequentially to form an oligomer, which can be further reacted with additional monomers or oligomers to form a polymer. By "oligomer" is meant a polymer or species that elutes below 3000 MW using a column calibrated with polyparaphenylenediamine terephthalamide homopolymer.

[0029] As used herein, the term "residue" of a chemical species refers to a moiety that is a product resulting from a chemical species in a particular reaction scheme or subsequent formulation or chemical product, regardless of whether the moiety is actually derived from the chemical species. Thus, a copolymer containing residues of paraphenylenediamine has the formula: [ka] It refers to a copolymer having one or more units of

[0030] Also, copolymers having residues of terephthaloyl dichloride have the formula: [ka] Contains one or more units of

[0031] Similarly, copolymers containing residues of imidazole groups, such as benzimidazole groups, can be represented by the formula: [ka] Contains one or more units of

[0032] Also specifically, copolymers containing residues of DAPBI have the formula: [ka] Contains one or more units of

[0033] Thus, in some embodiments, the aramid copolymer comprises residues of benzimidazole, and in some embodiments, the aramid copolymer comprises residues of 5(6)-amino-2-(p-aminophenyl).

[0034] Raw polymer particles The composite composition may contain particles of aramid copolymer containing imidazole groups, produced by grinding the copolymer to a desired size. For example, aramid polymer produced according to the teachings of U.S. Patent Application Publication No. 20130018138 is ground into water-wet acidic crumbs and coarsely ground while wet using various types of size reduction equipment, including hammer mills, disk mills, and roll mills. The acidic crumbs are then neutralized, preferably by washing with a base, and the neutralized crumbs are then isolated. The neutralized crumbs can then be dried to form polymer particles of irregular size, the majority of which pass through a mesh screen with 1.4 mm openings. Figure 1 is a photograph of these particles, which are referred to herein as "raw polymer" particles. The specific raw polymer particles were produced by polymerization of the monomers 5(6)-amino-2-(p-aminophenyl)benzimidazole, paraphenylenediamine, and terephthaloyl dichloride.

[0035] The size of the aramid copolymer particles described herein can be preferably determined by classification using any industrial method of sieving particles using a screen. An alternative method commonly used for very small particles is by laser diffraction using DIN ISO 13320-2020, which can also determine the fine particle size and their distribution.

[0036] A typical method for sieving particles uses a column of sieve trays of wire mesh screens with graduated mesh sizes. The material to be classified is poured onto the top sieve tray, which has the largest screen openings. Each lower sieve tray in the column has smaller openings than the one above. The column of sieve trays is typically placed in a mechanical shaker, which shakes all of the sieve trays in the column to facilitate particle movement across the surface of each mesh screen in each tray, so that particles small enough to pass through the screen openings can fall by gravity to the next sieve tray. After shaking is complete, the particles remaining on each mesh screen in each sieve tray are too large to pass through the openings of that mesh screen.

[0037] Although there are various systems for identifying mesh sizes, such as U.S. Standard Mesh or Tyler Mesh, any screen size will be identified herein by its opening in millimeters to avoid confusion. Additionally, as used herein, the openings in the screen are assumed to be square openings; for example, a mesh screen with 0.150 mm openings has openings that are square, with each side of the square opening being nominally 0.150 mm.

[0038] In some embodiments, the raw polymer particles comprising an aramid copolymer containing imidazole groups have a particle size distribution such that at least 90 weight percent of the particles will pass through a mesh screen having 1.4 mm openings, but 85 weight percent or more of the particles will not pass through a mesh screen having 0.212 mm openings. In other words, at least 75 weight percent of the raw polymer particles can be considered to be in the range of about 0.212 to 1.4 mm in size.

[0039] crushed particles Furthermore, the composite composition may contain raw polymer particles, but in some embodiments, the raw polymer particles containing the aramid copolymer containing imidazole groups are further milled to further reduce their particle size before their use in the composite composition. Such size reduction processes may include variations of the hammer mill, disk mill, roll mill, etc., as described above, as well as other processes such as jet mills and twin-screw extruders that can be used to reduce particle sizes to less than 1 mm, preferably less than 0.5 mm. In some preferred embodiments, a twin-screw extruder can be used as a mill to reduce the size of the aramid copolymer particles containing imidazole groups to particles with a desired particle size distribution.

[0040] In some embodiments, particles containing aramid copolymers containing imidazole groups have a particle size distribution such that they pass through a mesh screen with 0.425 mm openings, but about 50 weight percent do not pass through a mesh screen with 0.150 mm openings. As used herein, such particles containing aramid copolymers containing imidazole groups sized to this range are considered "ground particles" herein. In other words, ground particles can be considered to be smaller than about 0.425 mm, with about half of the particles being larger than 0.150 mm, meaning that the particles have a median particle size or diameter or D50 of about 0.150 mm.

[0041] One embodiment for utilizing a twin-screw extruder to produce "ground particles" comprising aramid copolymers containing imidazole groups is referred to herein as the "dry extruder" process. In this type of process, raw polymer, as described above, is further sized by the extruder in a dry state, i.e., the polymer being sized has less than 10% moisture by weight. Figure 2 is a photograph depicting these dry extruder particles. As in Figure 1, these ground particles were produced by polymerization of the monomers 5(6)-amino-2-(p-aminophenyl)benzimidazole, paraphenylenediamine, and terephthaloyl dichloride.

[0042] Another embodiment for producing aramid copolymer particles of less than 1 mm in size using a twin-screw extruder is referred to herein as the "wet extruder" process. In this type of process, the neutralized crumb from the polymerization is reduced to the desired size only once by the twin-screw extruder, and there is no intermediate step of producing raw polymer particles. Figures 3 and 4 are representative photographs of these wet extruder particles after air-drying in a shallow tray. These ground particles were also produced by polymerization of the monomers 5(6)-amino-2-(p-aminophenyl)benzimidazole, paraphenylenediamine, and terephthaloyl dichloride.

[0043] Particles containing aramid copolymers containing imidazole groups produced using a dry extruder process and particles containing aramid copolymers containing imidazole groups produced using a wet extruder are both considered "ground particles" in that they both fit the definition of ground particles herein. Any small differences in particle size distribution of the particles are not believed to affect their performance in the composite composition.

[0044] Floc particles In some embodiments, the particles comprising the aramid copolymer containing imidazole groups are in the form of floc in the composite composition. The term "floc," as used herein, refers to short-length fibers typically produced by cutting continuous fibers to the required length using methods well known in the art. In some preferred embodiments, the floc has a length of about 0.5 to about 15 millimeters. The preferred length of the floc is about 1 to about 12 millimeters, with the most preferred length being about 1 to 6 millimeters. In some embodiments, the floc may have a linear density of 0.5 to 3 denier per filament, and in some embodiments, the floc may have a linear density of 0.75 to 2.25 denier per filament.

[0045] Representative methods for producing floc include processes such as those described in U.S. Patent Nos. 8,501,071, 9,988,514, 9,994,974, 10,400,082, 10,400,357, and 11,279,800. Such processes may utilize a spinning solvent, such as sulfuric acid, and either polymer crumbs or raw polymer particles as previously described herein to form a suitable polymer spinning solution. Such processes preferably provide continuous filaments that are further cut into short lengths for use as floc.

[0046] Optionally, the composite composition can contain a mixture of either raw polymer particles or ground particles of an aramid copolymer containing imidazole groups with floc of an aramid copolymer containing imidazole groups. The weight ratio of particles to floc can range from 1:4 to 4:1. In some embodiments, the composite composition can contain a mixture of either raw polymer particles or ground particles of an aramid copolymer containing imidazole groups with a different type of reinforcing floc, such as carbon fiber floc or glass floc, again with a weight ratio of particles to floc in the range of 1:4 to 4:1. Alternatively, in some embodiments, the composite composition can contain a mixture of floc of an aramid copolymer containing imidazole groups with raw polymer particles or ground particles of a different polymer or copolymer type, again with a weight ratio of particles to floc in the range of 1:4 to 4:1.

[0047] Pellets of composite composition The particles of the aramid copolymer containing imidazole groups can be combined with the thermoplastic engineering polymer in any suitable vessel or device capable of mixing the materials and uniformly dispersing the particles throughout the engineering polymer. Such devices include batch mixers, LIST kneading reactor-type mixers, and single- or twin-screw extruders. Once the particles of the aramid copolymer containing imidazole groups have been combined with the thermoplastic engineering polymer to form a composite composition, the composite composition can be further shaped as needed, for example, to produce pellets from the composite composition for further use in various processes for manufacturing articles. For example, the molten composite composition can be produced in a twin-screw extruder, which further extrudes the molten composite composition through a die at the extruder exit to form molten strands of the composite composition that are thermally quenched. The solid or partially solid strands of the composite composition can then be directed to a pelletizer to produce pellets. In some embodiments, the pellets are sized so that there are 25 to 45 pellets per gram. In some other embodiments, the pellets have an average diameter of 1 to 3 mm.

[0048] Additionally, if desired, these pellets could be further milled to produce finer powders of the composite composition for use in specialized applications such as 3D printing or additive manufacturing processes. Microparticles are typically characterized as having a specific D50, which is the median particle size or particle size of the distribution. For example, for a powder sample with a D50 of 5 micrometers, this means that 50% of the particles are larger than 5 micrometers and 50% of the particles are smaller than 5 micrometers. This microparticle D50 is preferably measured by laser diffraction DIN ISO 13320-2020.

[0049] Fine powders of the composite composition having a D50 of 1 to 150 micrometers are believed to be useful. In some embodiments, these fine powders of the composite composition have a D50 of 30 to 150 micrometers. In some embodiments, the fine powders of the composite composition have a D50 of 45 to 120 micrometers, and in still other embodiments, the fine powders of the composite composition have a D50 of 48 to 100 micrometers.

[0050] Articles containing composite compositions Articles can be produced comprising the composite composition. In some embodiments, the articles include articles in which the aramid copolymer particles are the only particulates, other than optional pigments, incorporated into the engineering polymer. In some other embodiments, the articles include articles comprising aramid copolymer particles, optional pigments, and one or more fillers, where fillers are considered herein to be particles that do not affect the wear characteristics or wear performance (such as noise) of the article. In some other embodiments, the articles include articles in which the aramid copolymer particles are the predominant particulate additive, by weight, in the composite composition that is not a pigment or a filler. In yet some other embodiments, the articles include articles in which the aramid copolymer particles are the predominant particulate additive, by weight, in the composite composition that is not a pigment or a filler.

[0051] In many embodiments, preferred articles are parts made from the composite compositions while in the molten state, such as extruded and injection molded parts, or 3D printed or additively manufactured parts, such as by fused deposition modeling (FDM), stereolithography (SLA), or selective laser sintering (SLS). Such parts can be, for example, thin-walled parts or large industrial parts for use in the automotive and / or aerospace industries.

[0052] Abrasion resistance In many embodiments, the composite compositions and articles made therefrom have improved wear resistance. The addition of particles including an aramid copolymer containing imidazole groups reduces the wear rate of the thermoplastic engineering polymer by at least 25 percent, based on a comparison of the wear rate of a part made solely from the thermoplastic engineering polymer versus the wear rate of a part made with a composite composition containing a thermoplastic engineering polymer and particles including an aramid copolymer containing imidazole groups dispersed therein. In some embodiments, the addition of particles including an aramid copolymer containing imidazole groups reduces the wear rate of the thermoplastic engineering polymer by at least 45 percent. Surprisingly, the composite compositions and articles made therefrom have average dynamic coefficients of friction that are equal to or less than the average dynamic coefficient of friction of articles made solely from the thermoplastic engineering copolymer. In other words, surprisingly, the addition of these particles improves the wear performance of the material without increasing its coefficient of friction.

[0053] Process for producing composite compositions In some embodiments, the present invention provides a process for making a composite composition, comprising: a) polymerizing monomers to form an aramid copolymer comprising imidazole groups, the monomers comprising at least one aromatic diacid, at least one aromatic diamine, and one imidazole diamine; b) crushing and isolating the aramid copolymer containing imidazole groups in the form of polymer crumbs of a desired particle size, comprising the aramid copolymer containing imidazole groups; c) optionally further grinding or milling the polymer crumbs to form particles of a desired particle size comprising aramid copolymers containing imidazole groups; d) combining and mixing 3 to 30 parts by weight of the particles with up to 97 parts by weight of a thermoplastic engineering polymer to form a composite composition; The present invention relates to a process including:

[0054] It should be understood that all of the various elements, features, definitions and other descriptions provided herein above for the composite composition equally apply to the process of making the composite composition, but will not be repeated here to avoid redundancy.

[0055] In this process, step a) of polymerizing the monomers to form the aramid copolymer containing imidazole groups is preferably accomplished using the general teachings of solution polymerization, such as those disclosed in U.S. Patent Application Publication No. 20130018138. This process produces a wet polymer crumb, similar to wet sand, containing the polymerization solvent and the acidic by-products produced during the polymerization, typically hydrochloric acid.

[0056] In step b) of the process, the wet polymer crumbs are broken down and isolated by grinding or milling (e.g., using a hammer mill or disk mill) while washing the crumbs with water or an aqueous solution to remove the polymerization solvent from the crumbs. Optionally, the crumbs can be further washed with a base to remove acidic by-products from the polymerization. The isolated polymer can then optionally be dried.

[0057] The isolated crumbs can then optionally be further ground in step c) to further reduce the size of the crumbs by grinding or milling the polymer crumbs to a desired particle size. For example, as previously disclosed herein, the crumbs can be ground to produce raw polymer particles, or the crumbs can be ground to produce ground particles as previously described. Furthermore, for clarity, although it is discussed herein that the crumbs are first sized to raw polymer particles in step b), and then the raw polymer particles are further sized to ground particles in optional step c), it should be understood that it is possible to grind the polymer crumbs directly to "ground particles" in one step, step b). In some preferred embodiments, step c) is performed in a twin-screw extruder that reduces the material to a desired size.

[0058] The particles comprising the aramid copolymer containing imidazole groups are then combined and mixed in step d) with a thermoplastic engineering polymer in a ratio of 3 to 30 parts by weight of the particles to up to 97 parts by weight of the thermoplastic engineering polymer to form a composite composition. In some embodiments, 3 to 30 parts by weight of the particles are used in step d) along with 70 to 97 parts by weight of the thermoplastic engineering polymer to form a composite. In some embodiments, 5 to 25 parts by weight of the particles are used in step d) along with 75 to 95 parts by weight of the thermoplastic engineering polymer to form a composite.

[0059] Preferably, step d) is carried out in a twin-screw extruder. Typically, the thermoplastic engineering polymer is provided to the extruder in the form of solid pellets, which can be conveniently metered into the twin-screw extruder together with the particles comprising the aramid copolymer containing imidazole groups, where they can be combined and mixed to homogeneously disperse the particles comprising the aramid copolymer containing imidazole groups in the thermoplastic engineering polymer. Alternatively, the thermoplastic engineering polymer can be combined and mixed with the particles comprising the aramid copolymer containing imidazole groups using any number of batch, semi-continuous, or continuous methods using the thermoplastic engineering polymer in either solid or molten form.

[0060] In some embodiments, the process for producing the composite composition includes producing pellets of the composite composition during or after step d), for example, a pelletizing device can be connected to the outlet of the extruder, or the extruded composite composition can be pelletized in a separate step.

[0061] For example, the molten composite composition produced in a twin-screw extruder can be extruded through a die at the extruder outlet and subsequently thermally quenched to produce strands of the composite composition, which can then be directed to a pelletizer to produce pellets. Preferably, the pellets are sized so that there are 25 to 45 pellets per gram.

[0062] As discussed hereinabove, in some embodiments, the thermoplastic engineering polymer used in the process of making the composite composition comprises poly(ether ketone) (PEK), poly(ether ether ketone) (PEEK), poly(ether ketone ketone) (PEKK), or mixtures thereof. In some preferred embodiments, the thermoplastic engineering polymer used in the process of making the composite composition comprises poly(ether ether ketone) (PEEK). In some embodiments, the thermoplastic engineering polymer used in the process of making the composite composition comprises polyamide (PA), polyamide-imide (PAI), polyethersulfone (PES), polyether-imide (PEI), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyoxymethylene (POM), acetal copolymer (AC), polycarbonate (PC), or mixtures thereof.

[0063] The monomers used in polymerization step a) of the process for producing the composite composition can include any of the monomers described hereinabove. In some embodiments, the monomer includes an aromatic diacid terephthaloyl dichloride. In some embodiments, the monomer includes an aromatic diamine paraphenylenediamine. In some embodiments, the monomer includes an imidazole diamine in the form of a benzimidazole, preferably benzimidazole 5(6)-amino-2-(p-aminophenyl)benzimidazole. In some embodiments, the monomer includes 5(6)-amino-2-(p-aminophenyl)benzimidazole, paraphenylenediamine, and terephthaloyl dichloride.

[0064] As discussed hereinabove, the present process is useful for producing composite compositions having an average dynamic coefficient of friction that is equal to or less than the average dynamic coefficient of friction of thermoplastic engineering copolymers. [Example]

[0065] Test Method The wear rate reduction and coefficient of friction for each sample were measured using a friction and wear tester according to test method ASTM D3702 94.

[0066] A diameter of 1.3125 inches was used for the 3-pad washer (3PW) test. Test conditions were: linear velocity 0.18 m / min, pressure applied to each specimen 0.55 MPa, ambient temperature 21°C, and test time nominally 100 hours. The resulting PV was 0.1 MPa*m / s. ​​Each specimen was subjected to sliding contact with 4140 steel as the counter member. No lubricant was used in the test.

[0067] For thrust washer (TW) testing, a diameter of 1.125 inches was used. Test conditions included a machine speed of 500 RPM, corresponding to a linear speed of 0.7 m / min, a pressure of 1.75 MPa applied to each specimen, an ambient temperature of 21°C, and a nominal test time of 100 hours. The resulting PV was 1.2 MPa*m / s. ​​Each specimen was subjected to sliding contact with 4140 steel as the counter member. No lubricant was used in the testing.

[0068] The adhesive properties were measured according to DIN SPEC 19289:2022-08 “Fibre-reinforced composites—Measurement of Interfacial Shear Strength by means of a Micromechanical Single-Fibre Pull-Out Test.”

[0069] Example 1 An aramid copolymer containing imidazole groups was prepared as follows: Monomers 5(6)-amino-2-(p-aminophenyl)benzimidazole (DAPBI) and paraphenylenediamine (PPD) in amounts suitable to form a copolymer with a 70 / 30 DAPBI / PPD monomer ratio were combined with a stoichiometric amount of terephthaloyl dichloride (TCl) in a solvent system containing N-methyl-2-pyrrolidone (NMP) solvent and 4.5 weight percent calcium chloride (CaCl) as a solubility enhancer. The monomers were polymerized to form the copolymer.

[0070] After polymerization was complete, the copolymer crumbs were collected, ground (either by hammer mill or disk mill), and washed with sodium hydroxide to neutralize the by-product hydrochloric acid, resulting in raw polymer particles of approximately 3 mm in the form of wet, neutral crumbs. The copolymer had an intrinsic viscosity of about 6.4 dL / g. This procedure was repeated to produce another aramid copolymer containing imidazole groups with a 50 / 50 DABPI / PPD monomer ratio. This aramid copolymer also had an intrinsic viscosity of about 6.4 dL / g.

[0071] The raw polymer particles in the form of undried neutral crumbs were then either used directly in the wet extruder process or dried to form particles approximately 1 mm in size. The dried raw polymer was further processed into "dry extruder" ground particles by grinding approximately 1 mm raw polymer particles using solid-state grinding in a twin-screw extruder under dry conditions with less than 10% moisture. The "wet extruder" ground particles were produced by grinding samples of the undried neutral crumbs in a twin-screw extruder. Samples of dried 1 mm raw polymer particles were also used as shown in Table 2.

[0072] A portion of the 70 / 30 DABPI / PPD copolymer was converted into fibers, and the fibers were then chopped into flocs with a cut length of 3 mm. In addition, samples of glass fiber floc, carbon fiber floc, and polytetrafluoroethylene (PTFE) powder were also obtained for comparison. The sample items are summarized in Table 2.

[0073] [Table 2]

[0074] After obtaining the various particles, flocs, and powders, they were combined and blended with thermoplastic engineering resins using a twin-screw extruder. Items 1 to 10 in Table 1 were blended with polyether-ether-ketone polymers (PEEK 150G). TM The blend was blended with a 3-pad washer (purchased from Victrex). The extrusion temperature was maintained at 350-400°C. The blend was pelletized and isolated as pellets. The pellets were used in an injection molding machine operating at a melt temperature of 400°C and a mold temperature of 175°C to produce test items: 3-pad washers (3PW) for low pressure-speed testing and thrust washers (TW) for high pressure-speed testing, as shown in Table 3.

[0075] [Table 3]

[0076] Using a rotational wear test according to test method ASTM D3702-94, three-pad washers were tested for 70 to 96 hours with 4140 steel counterfaces. The pressure-rate for the three-pad washer test was 0.1 (MPa-m / s). Using the same test method, thrust washers were tested for 24 hours with 4140 steel counterfaces and a pressure-rate of 1.2 (MPa-m / s). Low pressure-rate wear rate data from the three-pad washer test are shown in Table 4. Blends of PEEK and aramid copolymers with imidazole groups showed reduced wear rates relative to the control. For this test, the dynamic coefficient of friction of the blended samples was substantially unchanged from that of the control sample.

[0077] [Table 4]

[0078] The high pressure-velocity wear rate data from the thrust washer test is shown in Table 5. The blends of PEEK and aramid copolymer with imidazole groups showed reduced wear rates relative to the control. For this test, the blends of PEEK and aramid copolymer with imidazole groups had dynamic friction coefficients lower than that of the control sample and approached the very low dynamic friction coefficient of the PTFE blend.

[0079] [Table 5]

[0080] Example 2 A portion of the fiber made from the 70 / 30 DABPI / PPD aramid copolymer produced in Example 1 was not cut into flock and used to measure the adhesion properties between the aramid copolymer and certain thermoplastic engineering polymers and to further compare the adhesion properties of those thermoplastic engineering polymers to the aramid copolymers versus, as a comparison, para-aramid paraphenylene terephthalamide (PPD-T) homopolymer.

[0081] The adhesive properties between materials were measured using a Textechno Fiber Matrix Adhesion Tester (FIMATEST) in accordance with DIN SPEC 19289:2022-08. This is a micromechanical method that involves embedding a single filament of aramid copolymer (or comparative material) in a matrix of thermoplastic engineering polymer. The fiber is then pulled out of the matrix at a constant rate of extension (CRE) while recording a force-displacement curve. From the apparent interfacial shear strength, the local interfacial shear strength and critical interfacial energy release rate can be determined. Specifically, each filament to be tested was embedded in a matrix of thermoplastic engineering polymer (TEP) as follows: The TEP was held in a crucible at room temperature and flushed with nitrogen for 5 minutes. The TEP temperature was raised above its melting temperature and held there for 10 minutes to completely melt the TEP. The filament was centered in the polymer matrix, and then embedded at a rate of 300 μm / min to a target embedment depth of 90 μm. The filament was held in place at 400°C for 30 seconds, then nitrogen cooled the matrix to 300°C during a 3 minute period, held at 300°C for 1 second, and then cooled to 50°C over 5 minutes. The sample was then held overnight at ambient temperature before drawing. Unfinished filaments were used in the tests.

[0082] Tables 6 and 7 summarize adhesion data generated using DIN SPEC 19289:2022-08. The data in these tables compare aramid copolymer filaments to PPD-T filaments in various engineering polymers, such as poly(ether ether ketone) (PEEK), polycarbonate (PC), and polyamide (PA) in the form of nylon 6 (PA-6). Specifically, Tables 6 and 7 compare the apparent interfacial shear strength (τ app ), local interfacial shear strength (τ d ) and the critical interfacial energy release rate (G ic) are summarized, with Table 6 providing data for "no finish" fiber materials and Table 7 providing data for fiber materials with a spin finish. This data illustrates the percent improvement (Δ) in adhesion to engineering polymers by aramid copolymers relative to PPD-T para-aramid homopolymer based on their adhesive properties. In addition, it was found that the presence of a spin finish does not impair adhesive performance but instead enhances the adhesive performance of aramid copolymer particles to engineering polymers, which would be an unexpected advantage of the use of flock particles in thermoplastic engineering polymer articles. Fiber finishes are usually desirable in fiber cutting operations to allow continuous filaments to be more easily chopped into flock, and it would be advantageous not to have to remove the finish from the chopped flock prior to its use as particles in composite compositions.

[0083] [Table 6]

[0084] [Table 7]

Claims

1. a) 3 to 30 parts by weight of particles comprising an aramid copolymer containing imidazole groups; b) up to 97 parts by weight of a thermoplastic engineering polymer; wherein said particles are uniformly dispersed in said thermoplastic engineering polymer and reduce the wear rate of said thermoplastic engineering polymer by at least 25 percent.

2. a) 5 to 25 parts by weight of the particles comprising an aramid copolymer containing imidazole groups; b) 75 to 95 parts by weight of a thermoplastic engineering polymer; The composite composition of claim 1 comprising:

3. 3. The composite composition of claim 1 or 2, wherein the particles comprising an aramid copolymer containing imidazole groups reduce the wear rate of the thermoplastic engineering copolymer by at least 45 percent.

4. 4. The composite composition of claim 3, wherein the particles comprising an aramid copolymer containing imidazole groups reduce the wear rate of the thermoplastic engineering copolymer by at least 80 percent.

5. 5. The composite composition of claim 1, wherein the thermoplastic engineering polymer is poly(ether ketone) (PEK), poly(ether ether ketone) (PEEK), poly(ether ketone ketone) (PEKK), or a mixture thereof.

6. 6. The composite composition of claim 5, wherein the thermoplastic engineering polymer is poly(ether ether ketone) (PEEK).

7. 7. The composite composition of any one of claims 1 to 6, wherein the thermoplastic engineering polymer comprises polyamide (PA), polyamide-imide (PAI), polyethersulfone (PES), polyether-imide (PEI), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyoxymethylene (POM), acetal copolymer (AC), polycarbonate (PC), or a mixture thereof.

8. The local interfacial shear strength (τ) between the particles of aramid copolymer containing imidazole groups and the engineering polymer d ) is the local interfacial shear strength (τ ) between particles of a para-aramid homopolymer, such as PPD-T, and the same engineering polymer. d 8. The composite composition according to claim 1, wherein the .lambda.

9. The local interfacial shear strength (τ) between the particles of aramid copolymer containing imidazole groups and the engineering polymer d ) is the local interfacial shear strength (τ d 9. The composite composition of claim 8, wherein the .alpha.-to-.alpha. ratio is at least 9 percent greater than .alpha.-to-.alpha. ratio.

10. The local interfacial shear strength (τ) between the particles of aramid copolymer containing imidazole groups and the engineering polymer d ) is the local interfacial shear strength (τ d 10. The composite composition of claim 9, wherein the .alpha.-to-.alpha. ratio is at least 35 percent greater than .alpha.-to-.alpha. ratio.

11. The local interfacial shear strength (τ) between the particles of aramid copolymer containing imidazole groups and the engineering polymer d 11. The composite composition according to claim 1, wherein the compressive strength is 72 MPa or more.

12. The composite composition of any one of claims 1 to 11, wherein the aramid copolymer containing imidazole groups comprises residues of paraphenylenediamine.

13. 13. The composite composition of claim 12, wherein the aramid copolymer containing imidazole groups further comprises residues of 5(6)-amino-2-(p-aminophenyl)benzimidazole, and the molar ratio of the residues of 5(6)-amino-2-(p-aminophenyl)benzimidazole to the residues of paraphenylenediamine is from 50 / 50 to 80 / 20.

14. 14. The composite composition of claim 13, wherein the aramid copolymer containing imidazole groups further comprises residues of 5(6)-amino-2-(p-aminophenyl)benzimidazole, and the molar ratio of the residues of 5(6)-amino-2-(p-aminophenyl)benzimidazole to the residues of paraphenylenediamine is from 50 / 50 to 70 / 30.

15. 15. The composite composition of any one of claims 1 to 14, wherein the aramid copolymer containing imidazole groups comprises residues of 5(6)-amino-2-(p-aminophenyl)benzimidazole.

16. 16. The composite composition of any one of claims 1 to 15, wherein the particles comprising the aramid copolymer containing imidazole groups are in the form of crushed or ground polymeric crumbs.

17. 17. The composite composition of any one of claims 1 to 16, wherein the particles comprising the aramid copolymer comprising imidazole groups have a particle size distribution such that 90 percent by weight of the particles pass through a mesh screen having 1.4 mm openings and 85 percent by weight or more of the particles do not pass through a mesh screen having 0.212 mm openings.

18. 17. The composite composition of any one of claims 1 to 16, wherein the particles comprising the aramid copolymer comprising imidazole groups have a particle size distribution such that the particles pass through a mesh screen having 0.425 mm openings and 50 weight percent do not pass through a mesh screen having 0.150 mm openings.

19. The composite composition according to any one of claims 1 to 15, wherein the particles comprising the aramid copolymer containing imidazole groups are in the form of flocs.

20. 20. The composite composition of claim 19, wherein the floc has a cut length of 0.5 to 15 millimeters.

21. 21. The composite composition of claim 20, wherein the floc has a cut length of 1 to 6 millimeters.

22. An article comprising the composite composition of any one of claims 1 to 21.

23. 23. The article of claim 22, having an average dynamic coefficient of friction that is equal to or less than the average dynamic coefficient of friction of an article consisting solely of said thermoplastic engineering copolymer.

24. 23. The article of claim 22 in the form of extruded pellets sized such that there are 25 to 45 pellets per gram.

25. 25. The article of claim 22 or 24 in the form of extruded pellets having an average diameter of 1 to 3 mm.

26. 1. A process for producing a composite composition, comprising: a) polymerizing monomers to form an aramid copolymer comprising imidazole groups, said monomers comprising at least one aromatic diacid, at least one aromatic diamine, and one imidazole diamine; b) crushing and isolating the aramid copolymer containing imidazole groups in the form of polymer crumbs of a desired particle size, said aramid copolymer containing imidazole groups; c) optionally further grinding or milling the polymer crumbs to form particles of a desired particle size comprising aramid copolymers containing imidazole groups; d) combining and mixing 3 to 30 parts by weight of said particles with up to 97 parts by weight of a thermoplastic engineering polymer to form said composite composition; A process involving:

27. 27. The process for making a composite composition according to claim 26, wherein the thermoplastic engineering polymer is poly(ether ketone) (PEK), poly(ether ether ketone) (PEEK), poly(ether ketone ketone) (PEKK), or a mixture thereof.

28. 28. The process for making a composite composition according to claim 27, wherein the thermoplastic engineering polymer is poly(ether ether ketone) (PEEK).

29. 29. The process for making a composite composition according to any one of claims 26 to 28, wherein the thermoplastic engineering polymer comprises polyamide (PA), polyamide-imide (PAI), polyethersulfone (PES), polyether-imide (PEI), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyoxymethylene (POM), acetal copolymer (AC), polycarbonate (PC), or a mixture thereof.

30. 30. The process for producing the composite composition of any one of claims 26 to 29, wherein the aromatic diacid is terephthaloyl dichloride.

31. The process for producing a composite composition according to any one of claims 26 to 30, wherein the aromatic diamine is paraphenylenediamine.

32. 32. The process for preparing a composite composition according to any one of claims 26 to 31, wherein the imidazole diamine is 5(6)-amino-2-(p-aminophenyl)benzimidazole.

33. A process for producing a composite composition according to any one of claims 26 to 32, wherein step c) is carried out in a twin-screw extruder.

34. The process for producing a composite composition according to any one of claims 26 to 33, wherein step d) is carried out in a twin-screw extruder.

35. 35. The process for producing a composite composition according to any one of claims 26 to 34, wherein pellets of the composite composition are produced during or after step d).

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