Long-fiber thermoplastic compositions from random copolymer polyamides

Abstract

Disclosed is a method to produce a strengthened thermoplastic through the integration of long fibers into a specific random copolymer polyamide matrix. The copolymer consists predominantly of hexamethylene adipamide and / or tetramethylene adipamide units and contains from 1 to 40 wt-% of a monomer comprising a branched aliphatic group. The random copolymer is present in the composition in an amount of at least 80 wt-% of all polyamides present in the composition.

Description

[0001] LONG-FIBER THERMOPLASTIC COMPOSITIONS FROM RANDOM COPOLYMER POLYAMIDES

[0002] RELATED APPLICATION

[0003] This Application claims the benefit of priority to United Kingdom Application No. 2309098.8, filed on June 16, 2023. The above-referenced patent application is herein incorporated by reference in its entirety.

[0004] FIELD OF THE INVENTION

[0005] The present application relates to a method of making a long-fiber-reinforced thermoplastic composition, such as by D-LFT molding, from a random copolymer polyamide composition, wherein the properties of the random copolymer polyamide are particularly well-suited for use in methods such as D-LFT molding, including when the random copolymer polyamide is used as the only polyamide present in the composition.

[0006] CROSS REFERENCE TO RELATED APPLICATIONS

[0007] This patent application is related by disclosure of similar subject matter to WO2021079244, WO2022130293, and W02023007116, which are herein incorporated by reference.

[0008] BACKGROUND

[0009] Direct Long Fiber Thermoplastic (D-LFT) molding requires a combination of good flowability in the melt, prompt wetting of reinforcing fibers and controlled crystallization below the melt temperature for ease of mold release and good surface appearance or finish. This combination of properties can be difficult to achieve. One solution is to physically mix two different formulations of nylon chip. For example, a first nylon chip could comprise a low-relative viscosity (RV) nylon-6, 6 to provide good flowability in the melt. A second nylon chip could comprise a random copolymer of hexamethylene adipamide (nylon-6, 6) and 2-methyl-l,5- pentamethylene isophthalamide (nylon-DI) with a slower rate of crystallization than nylon-6, 6. The nylon-6, 6 and nylon-6, 6 / DI could then be physically mixed or melt co-extruded to obtain a homogenized polymer. To reliably make parts, a D-LFT molding resin needs to wet the surface of the incorporated reinforcing fibers. Poor wetting leads to poor or non-optimal mechanical as well as surface properties. This wetting step needs to follow the melting step as soon as possible. Prompt wetting of the reinforcing fibers allows the reinforcing fibers to evenly distribute in the melt and will aid in the formation of parts as the D-LFT brick / plastificate is pressed into the mold. If the polymer is not viscous enough, then an evenly falling film of polymer from the waterfall or slit die of the D-LFT unit will deform, resulting in poor wetting of the reinforcing fiber. If the polymer viscosity is too high then the molten polymer will not flow into the intestacies between the reinforcing fibers, again giving poor wetting.

[0010] The molten polymer of the falling film from the waterfall or slit die needs to be homogeneous in terms of its viscosity and composition across the film. If some parts have higher or lower viscosity than other parts of the film, then wetting of the fiber will not be even. If the polymer is too fast to crystallize, it may start to crystallize whilst being held post plastificate formation but prior to molding and give poor moldings and / or poor mechanical properties, and / or poor surface appearance. Alternatively, if the polymer is too slow to crystallize, the mechanical properties of the molded part will be impaired.

[0011] The use of two, or more, different nylon chip formulations in a multi-feedstock solution is not without technical issues. For example, melting and molding process conditions are also suitable for promoting transamidation reactions. Transamidation of two polyamides of different compositions eventually leads to a random copolymer of the two polymers via intermediate compositions of some degree of blockiness. Similarly, mixing melts of two polyamides of different molecular weights, or end group compositions, will over time lead eventually to some form of stable composition intermediate between the two starting compositions. For this reason, the properties of the molding resin change as a function of time under melt processing and molding conditions. Thus, the crystallization rate and the melt viscosity of the molding resin are actively changing during these processes. In addition, there are cost and quality implications of handling more than one starting material, namely, quality variability, mixing homogeneity, processing complexity, procurement, handling, storage, conveying, etc. There are also other commercial advantages to supplying a single feedstock, such as mitigating the substitution for competitor materials of one or more components in a multi-feedstock solution. The present invention addresses these problems.

[0012] United States Patent Application Publication No. 5204396 is directed to polyamide resin compositions and to molded articles formed thereof which is composed of a blend of a polyamide base resin, a long fiber reinforcement medium, and a processing aid which is at least one selected from (i) a lithium salt of a fatty acid, or (ii) a metal salt of a fatty acid having between 22 to 32 carbon atoms.

[0013] United States Patent Application Publication No. 20170166713 relates to a composition comprising: a) PA6 or PA66 or a copolyamide of PA6 or PA66, b) at least one thermal stabilizer, c) at least one amide wax and / or at least one ester wax, and d) a long fiber reinforcement which comprises: not less than 90 wt % of fibers having a fiber diameter of 5 to 25 pm, of which not less than 80% of the fibers have a length of at least 5 mm, and up to 10 wt % of at least one added-substance material.

[0014] United States Patent Application Publication No. 20190211165 describes a method of producing a fiber-reinforced composition comprising long fibers, the method comprising: (la) mixing and melting, a) PA6 or PA66 or a copolyamide of PA6 or PA66, b) at least one thermal stabilizer, and c) at least one amide wax and / or at least one ester wax.

[0015] Degradation of Glass Fiber Reinforced Polyamide Composites during Long Fiber Reinforced Thermoplastic Direct Extrusion Compression Molding Process is studied and reported by T Whitfield et. Al., in SPE ANTEC Indianapolis 2016, 347.

[0016] Experimental characterization and modelling of the elastic properties of direct compounded compression molded carbon fibre / polyamide 6 long fibre thermoplastic is studied and reported M. Bondy et. Al., in Materials and Design. 2017, 122, 184-196. Tensile fatigue characterization of polyamide 66 / carbon fiber direct / in-line compounded long fiber thermoplastic composites is studied and reported by M. Bondy, W. Rodgers, W. Aletenhof in Composites. Part B.; 2019, 173, 106984.

[0017] WO2021 / 181362A1 relates to injection molding polyamide copolymers but does not disclose a method for making long-fiber reinforced polyamide compositions.

[0018] There are technical problems associated with the long-fiber processing of a thermoplastic polymer including nylons. Some of the problems may include breaking of the fiber reinforcement medium into shorter fiber segments during processing and thereby resulting in the decreased stiffness and poor strength, heterogeneities affecting the mechanical performance and surface appearance of the molded part, and such.

[0019] Although various combinations of polymers and fibers can be developed, this approach is also faced with further problems. For example, D-LFT process molded parts made from polypropylene have relatively lower mechanical properties and application temperatures compared to engineered thermoplastics. Substituting polypropylene with a polyamide [PA] may improve certain properties. However, concerns with processing PA still exist due to the higher processing temperatures; higher viscosities; oxidation sensitivity; higher water absorption; and increased fiber breakup.

[0020] It is therefore desirable for the properties of the molding resin to be well-suited to D-LFT, and more predictable as a function of time during the molding process. The present invention addresses this need in the art.

[0021] SUMMARY OF THE INVENTION

[0022] Disclosed is a method of making a long-fiber-reinforced thermoplastic composition, such as by D-LFT molding, from a polyamide composition comprising a random copolymer polyamide, wherein the random copolymer polyamide is particularly well-suited for use as the majority polymer component in processes such as D-LFT molding. The present invention provides a method of making a long-fiber-reinforced thermoplastic composition, the method comprising: a) providing a random copolymer polyamide composition comprising a random copolymer polyamide; wherein the random copolymer polyamide comprises: i) from 60 to 99 wt%, based on the total mass of the copolymer, of first amide monomer units derived from hexamethylene adipamide, tetramethylene adipamide, or combinations thereof; and ii) from 1 to 40 wt%, based on the total mass of the copolymer, of second amide monomer units that are different from the first amide monomer units; wherein the second amide monomer units comprise a branched aliphatic group; wherein the random copolymer polyamide is present in the random copolymer polyamide composition in an amount of >90wt% relative to the total amount of all polyamides present in the composition; and wherein the method comprises the steps of: b) heating said random copolymer polyamide composition to afford a melt phase; and c) introducing a reinforcing fiber, to the melt phase to afford the long-fiber- reinforced thermoplastic composition; wherein the long-fiber-reinforced thermoplastic composition comprises the reinforcing fiber in at least 25 wt% relative to the total weight of the long-fiber-reinforced thermoplastic composition.

[0023] The random copolymer polyamide for use in the invention can comprise >95% by weight of all polyamide components in the random copolymer polyamide composition, for example >99% by weight of all polyamide components in the random copolymer polyamide composition.

[0024] The long-fiber-reinforced thermoplastic composition may be a fiber-reinforced thermoplastic afforded from a D-LFT molding method. In other words, the method of the invention may be D- LFT molding.

[0025] The method of the invention may further comprise step d) molding the long-fiber-reinforced thermoplastic composition to form a product. The second amide monomer units comprise an aromatic group and / or a branched aliphatic group.

[0026] The random copolymer polyamide may be selected from the group of random copolymers consisting of PA66 / DI, PA66 / D6, PA66 / 6I / DT, PA66 / 6I / DI, PA66 / 6T / DT, and PA66 / 6T / DI. The random copolymer polyamide may be PA66 / DI. The random copolymer polyamide may be PA66 / 6T / DI.

[0027] The remainder of other polyamide components may comprise of masterbatches of additives as is well known and practiced in the art for ease of use and convenience.

[0028] The invention further provides a method of D-LFT molding a random copolymer polyamide composition comprising a random copolymer polyamide; wherein the random copolymer polyamide comprises: i) from 60 to 99 wt%, based on the total mass of the copolymer, of first amide monomer units derived from hexamethylene adipamide, tetramethylene adipamide, or combinations thereof; and ii) from 1 to 40 wt%, based on the total mass of the copolymer, of second amide monomer units that are different from the first amide monomer units; wherein the second amide monomer units comprise a branched aliphatic group; wherein the random copolymer polyamide is present in the random copolymer polyamide composition in an amount of >80wt% relative to the total amount of all polyamides present in the composition (for example, 85, 90, 95, 97 or 99wt%); and wherein the method comprises the steps of: a) providing said random copolymer polyamide composition; and b) molding said random copolymer polyamide composition using a D-LFT molding process to afford a fiber- compounded thermoplastic resin composition comprising a reinforcing fiber; wherein the long-fiber-reinforced thermoplastic composition comprises the reinforcing fiber in at least 25 wt% relative to the total weight of the long-fiber-reinforced thermoplastic composition. The random copolymer polyamide may be selected from the group consisting of PA66 / DI and PA66 / 6T / DI.

[0029] It has now been found that certain combinations of diacids and diamines can be reacted by condensation polymerization to form a random copolymer having stable and predictable properties during the formation of long-fiber-reinforced thermoplastic compositions, such as by D-LFT molding. The random copolymers for use in the invention can be used as effectively a single polyamide (comprising > 90 w% of all polyamide components, (for example, 85, 90, 95, 97 or 99wt%)) during formation of long-fiber-reinforced thermoplastic compositions, such as by D-LFT molding, eliminating the problems associated with transamidation, which are inherent in the previously used two-chip systems.

[0030] The method of the present invention is particularly well-suited for D-LFT molding. However, the easy flow and reduced crystallization temperatures of the copolymers for use in the invention are properties that will provide similar advantages when utilized in other processes where products of high filler loadings are required, such as pultrusion manufacturing, as well as methods for making organosheets; unidirectional tapes, woven mats, and non-woven mats.

[0031] DETAILED DESCRIPTION OF THE INVENTION

[0032] Definitions

[0033] Reference will now be made in detail to certain aspects of the disclosed subject matter, examples of which are illustrated in part in the accompanying drawings. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the exemplified subject matter is not intended to limit the claims to the disclosed subject matter.

[0034] Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of “about 0.1% to about 5%” or “about 0.1% to 5%” should be interpreted to include not just about 0.1% to about 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement “about X to Y” has the same meaning as “about X to about Y,” unless indicated otherwise. Likewise, the statement “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z,” unless indicated otherwise.

[0035] In this document, the terms “a,” “an,” or “the” are used to include one or more than one unless the context clearly dictates otherwise. In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section.

[0036] In the methods described herein, the acts can be carried out in a specific order as recited herein. Alternatively, in any aspect(s) disclosed herein, specific acts may be carried out in any order without departing from the principles of the invention, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit claim language recites that they be carried out separately or the plain meaning of the claims would require it. For example, a claimed act of doing X and a claimed act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.

[0037] The term “about” as used herein can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range, and includes the exact stated value or range. The term “substantially” as used herein refers to a majority of, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%. The term “substantially free of’ as used herein can mean having none or having a trivial amount of, such that the amount of material present does not affect the material properties of the composition including the material, such that about 0 wt% to about 5 wt% of the composition is the material, or about 0 wt% to about 1 wt%, or about 5 wt% or less, or less than or equal to about 4.5 wt%, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01, or about 0.001 wt% or less, or about 0 wt%.

[0038] As used herein, the term “PA66” refers to poly(hexamethylene adipamide).

[0039] As used herein, the term “PA66 / DI” refers to a type of co-polyamide formed by combining hexamethylene adipamide salt solution with DI salt solution, where “D” is an abbreviation for 2- methyl- 1,5 -pentamethylene diamine (also known as MPMD), and “I” is an abbreviation for isophthalic acid.

[0040] As used herein, the term “PA66 / 610” refers to a type of co-polyamide formed by combining hexamethylene adipamide salt solution with 610 salt solution, where “610” is an abbreviation for hexamethylene sebacamide.

[0041] As used herein, the term “PA66 / 6I” refers to a type of co-polyamide formed by combining hexamethylene adipamide salt solution with 61 salt solution, where “61” is an abbreviation for hexamethylene isophthalamide.

[0042] As used herein, the term “PA66 / 6T” refers to a type of co-polyamide formed by combining hexamethylene adipamide salt solution with 6T salt solution, where “6T” is an abbreviation for hexamethylene terephthalamide.

[0043] As used herein, the term “PA66 / D6” refers to a type of co-polyamide formed by combining hexamethylene adipamide salt solution with D6 salt solution, where “D6” is an abbreviation for 2-methyl-l ,5-pentamethylene adipamide.

[0044] As used herein, “PA6I / 6T” refers to a co-polyamide formed by combining a salt of hexamethylene diamine and isophthalic acid, abbreviated as “I”, with that of hexamethylene diamine and terephthalic acid, abbreviated as “T”. PA6I / 6T is also known as a copolyamide of hexamethylene isophthalamide and hexamethylene terephthalamide. As used herein, the term “PA66 / 6T / DI” refers to a type of co-polyamide formed by combining hexamethylene adipamide salt solution with 6T salt solution and a DI salt solution, where “6T” is an abbreviation for hexamethylene terephthalamide and “DI” is an abbreviation for 2-methyl- 1 ,5-pentamethylene isophthalamide.

[0045] A random copolymer is a polymer comprising at least two different monomeric units, wherein said monomeric units are distributed randomly along the polymer chain.

[0046] For the purposes of the present invention, a polyamide monomer unit is defined as a monomeric unit derived from a diacid and a diamine, e.g., hexamethylene terephthalamide.

[0047] The term “melt phase” refers to when the copolymer composition for use in the invention is in liquid form.

[0048] “Long fiber” in the context of the long fiber reinforced thermoplastic composition of the invention refers to a composition wherein at least 25% of the fibers have a length > 0.5 mm, as determined by the number-averaged fiber length.

[0049] Method of Making a Long-Fiber-Reinforced Thermoplastic Composition, Including the Use of Direct-Long Fiber Thermoplastic (D-LFT) Molding

[0050] The present invention provides a method of making a long-fiber-reinforced thermoplastic composition, such as by D-LFT molding, using a random copolymer polyamide composition that is particularly well-suited for use in this process. In particular, the random copolymer polyamide composition does not undergo transamidation reactions during melt processing, such that the properties of the molding resin are predictable as a function of time during the molding process. Moreover, the random copolymer polyamide composition has a rate of crystallization that is slow enough to be compatible with the formation of long-fiber-reinforced thermoplastic composition, such as by D-LFT molding, but fast enough to ensure that the resulting material is crystalline, and the products have good mechanical properties.

[0051] The method of the invention may comprise providing the random copolymer polyamide composition for use in the invention, heating said random copolymer polyamide composition to afford a melt phase, and introducing reinforcing fiber to the melt phase to afford a long-fiber- reinforced thermoplastic composition. The method may further comprise molding said long- fiber-reinforced thermoplastic composition to form a product. The long-fiber-reinforced thermoplastic composition may be a D-LFT, i.e., the method of the invention is D-LFT molding.

[0052] The long-fiber-reinforced thermoplastic composition may also be selected from the group consisting of a direct long-fiber thermoplastic (D-LFT), a fiber reinforced thermoplastic afforded from a pultrusion manufacturing method, an organosheet; a unidirectional tape, a woven mat, and a non-woven mat.

[0053] In D-LFT, a granulated thermoplastic resin material, such as, the compounded feed or the polyamide itself, along with any other desired additives, is fed to the extruder front and the resultant resin melt is blended with a roving material (e.g.: glass fiber, carbon fiber, natural fibers, etc.) before entering an LFT unit. The resin melt may then be extruded through a slit die to form a “waterfall” or “film” of molten resin into which the roving material is introduced and pulled through to coat and wet the roving material before entering the LFT unit. The roving material maybe continuous. Alternatively, the roving material may also be dis-continuous and can be orientated lengthways to feed to the “waterfall” of the resin melt.

[0054] Within the LFT unit, the fiber filled resin can be extruded as a thick beam and cut to form a “plastificate”, which may somewhat resemble a “brick” or block of material. The LFT extrudate / plastificate containing the / fiber and molten resin portions maybe robotically transported to a conveyer belt and fed into a hot oven for a time before again being robotically transported to a low cycle time profile press for molding into a desired part profile. The profiled parts maybe robotically transported to the downstream processing section for finished articles, for example, fabrics, sheets, plaques, etc.

[0055] D-LFT processing can be performed using a temperature of 200 to 400 °C, such as 300°C, for the conveyor belt / hot oven, 60 to 100 °C, such as 80°C mold temperature, 40 to 100 second, such as 60 second, cooling time, 200 to 400 °C, such as 290 °C barrel temperature, and 100 to 300 RPM, such as about 200 RPM screw speed of the extruder. The polymer melt mass temperature may be in the 280-290 °C range.

[0056] Compounded Feed for the D-LFT Process.

[0057] Methods and apparatus well known in the art, such as twin-screw extruders, may be used to compound additives into the polyamide prior to delivery to the D-LFT process. For example, the method may include using a twin-screw extruder, co-rotating and turning at a suitable speed, such as 300 RPM. The barrel may be heated along its length in zones at temperatures, typically 270-320°C for copolyamides, to melt the polymer. The processing section of the twin screw compounder may be set up to suit various process needs and to facilitate a wide variety of processes, such as compounding. The random copolymer polyamide composition, optionally comprising fillers and additives, as desired, can be continuously fed into the first barrel section of the twin screw using a metering feeder. The materials may then be conveyed along the screw and get melted and mixed by kneading elements in the plastification section of the barrel.

[0058] The polyamide composition can then pass onto degassing zones, and from there to a pressure build zone where it can then exit the die via holes (e.g., 3-mm diameter) as a lace. The cast lace can feed into a water bath to cool and to enable it to be cut into chips via a pelletizer. The method may include compounding the polyamide with the flame-retardant additive or another additives, such as a masterbatch of heat stabilisers; a masterbatch of colourants; and others well known in the art.

[0059] Random Copolymer Polyamide Composition for Use in the Invention

[0060] The inventors have discovered a random copolymer polyamide composition that is particularly well-suited for used in making a long-fiber-reinforced thermoplastic composition, such as by D- LFT molding. The random copolymer amide composition for use in the invention comprises a random copolymer polyamide as defined herein and, optionally, additives.

[0061] The random copolymer polyamide is present in the random copolymer polyamide composition in an amount of >80wt% relative to the total amount of all polyamides present in the composition. Preferably, the random copolymer polyamide is present in the random copolymer polyamide composition in an amount of >85wt%, >90wt%, or >93wt% relative to the total amount of all polyamides present in the composition, more preferably >95wt%, more preferably >97wt%, more preferably >98wt%, and even more preferably >99wt% relative to the total amount of all polyamides present in the composition. The random copolymer polyamide composition for use in the invention may comprise the random copolymer polyamide as the only polyamide present in the composition.

[0062] The inventors have found that by incorporating the random copolymer polyamide for use in the invention into the random copolymer polyamide composition in the amount required, transamidation reactions are eliminated. Accordingly, the random copolymer polyamide composition has consistent and predictable properties in the melt phase. Moreover, the inventors found that the random copolymer polyamide composition for use in the invention has the properties required to afford D-LFT molding products with the desired mechanical properties, as discussed herein.

[0063] Preferably, the random copolymer polyamide for use in the invention is present in the random copolymer polyamide composition in an amount of at least 80wt%, such as at least 85wt%, relative to the total mass of the random copolymer polyamide composition. More preferably, the random copolymer polyamide is present in the random copolymer polyamide composition for use in the invention in an amount of at least 90wt% relative to the total mass of the random copolymer polyamide composition, and even more preferably at least 95 or 97wt% relative to the total mass of the random copolymer polyamide composition.

[0064] Random Copolymer Polyamide for Use in the Invention

[0065] The inventors have found that random copolymer polyamides having crystallization temperatures of less than or equal to 200 °C are particularly well suited for use in making a long-fiber- reinforced thermoplastic composition, such as by D-LFT molding. The crystallization temperature is measured according to the method described herein. Preferably, the random copolymer polyamides for use in the invention have a crystallization temperature of less than 198 °C, such as less than 195 °C. Without wishing to be bound by theory, the inventors postulate that random copolymer polyamides with crystallization temperatures of less than or equal to 200 °C have crystallization rates slow enough so that crystallization does not occur whilst the material is being held post plastificate formation, but fast enough so that the resulting products are crystalline (i.e., not amorphous with the associated poor mechanical properties).

[0066] The inventors have also found that random copolymer polyamides having enthalpies of crystallization greater than 20 J / g are particularly well suited for making a long-fiber-reinforced thermoplastic composition, such as by D-LFT molding. The crystallization enthalpy is measured according to the method described herein. Preferably, the random copolymer polyamides for use in the invention have a crystallization enthalpy of greater than 30 J / g, such as greater than 40 J / g, or even more preferably greater than 50 J / g.

[0067] Without wishing to be bound by theory, the inventors postulate that random copolymer polyamides having these crystallization enthalpies provide products with good mechanical properties. For example, articles produced using the method of the invention have, in the length direction, tensile strengths of at least 130 MPa, elongations at break of at least 2.5%, and Charpy notched impact test strengths of at least 20 kJ / m2. Moreover, articles produced using the method of the invention have, in the width direction, tensile strengths of at least 55 MPa, elongations at break of at least 10%, and Charpy notched impact test strengths of at least 6.5 kJ / m2

[0068] Preferably, the random copolymer polyamides for use in the invention have a relative viscosity in formic acid (RVF) of 20 to 60 and more preferably 30 to 50. The relative viscosity in formic acid is determined using the method described in the examples. The relative viscosity is the ratio of the viscosity of the solution to the viscosity of the solvent. As discussed, the relative viscosity is an important parameter for materials used in making a long-fiber-reinforced thermoplastic composition, such as by D-LFT molding.

[0069] The random copolymer polyamides for use in the invention can have any suitable amine end group (AEG) value, such as an AEG value of 30 to 130 milliequivalents / kg (meq / kg). Preferably, the random copolymer polyamide for use in the invention has an AEG value of 30 meq / kg to 70 meq / kg, more preferably 40 meq / kg to 65 meq / kg, and even more preferably 50 meq / kg to 63 meq / kg.

[0070] Monomeric Composition

[0071] The random copolymer polyamide for use in the invention comprises 60 to 99 wt%, based on the total mass of the copolymer, of first amide monomer units derived from hexamethylene adipamide, tetramethylene adipamide, or combinations thereof, and from 1 to 40 wt%, based on the total mass of the copolymer, of second amide monomer units that are different from the first amide monomer units.

[0072] The first amide monomer unit is preferably derived from hexamethylene adipamide.

[0073] The second monomer units comprise a branched aliphatic group and may further comprise a moiety selected from the group consisting of an aromatic group a linear aliphatic group (e.g., 610), an alicyclic group, and combinations thereof. The second monomer units preferably comprise an aromatic group (e.g., 61, 6T, DI, DT). The second monomer units comprise a branched aliphatic group (e.g., D6, DI, DT). More preferably, the second monomer units comprise both an aromatic group and a branched aliphatic group, for example, wherein the aromatic group and branched aliphatic group are present within a single monomer unit (e.g., DI, DT).

[0074] The presence in random copolymer polyamides of second amide monomer units comprising a branched aliphatic group affords advantages, as discussed herein, when they are used in processes for making long-fiber reinforced thermoplastic compositions.

[0075] The second monomer unit is further preferably derived from the group of monomers consisting of 2-methyl- 1 ,5-pentamethylene-isophthalamide, 2-methyl- 1 , 5-pentamethylene-terephthalamide, and combinations thereof. The random copolymer polyamide for use in the invention may preferably be selected from the group of random copolymers consisting of PA66 / DI, PA66 / D6, PA66 / 6I / DT, PA66 / 6I / DI, PA66 / 6T / DT, and PA66 / 6T / DI.

[0076] The random copolymer polyamide for use in the invention is preferably a copolymer comprising (as part i) monomer units derived from hexamethylene adipamide and (as part ii) monomer units derived from -methyl-l,5-pentamethylene-isophthalamide, 2-methyl-l,5-pentamethylene- terephthalamide, or combinations thereof. The random copolymer polyamide for use in the invention is more preferably a copolymer comprising (as part i) monomer units derived from hexamethylene adipamide and (as part ii) monomer units derived from -methyl- 1,5- pentamethylene-isophthalamide (i.e., a PA66 / DI copolymer). Said copolymer may have a wt% ratio of monomer units of part i) to monomer units of part ii) of 97:3 to 82: 18; preferably 95:5 to 85: 15; and more preferably 93:7 to 87: 13.

[0077] The random copolymer polyamide for use in the invention preferably comprises from 80 to 99 wt%, such as 85 to 95 wt%, based on the total mass of the copolymer, of first amide monomer units derived from hexamethylene adipamide, tetramethlyene adipamide, or combinations thereof, and from 1 to 20 wt%, such as 5 to 15 wt%, based on the total mass of the copolymer, of second amide monomer units comprising aromatic and / or branched aliphatic groups (i.e., from 97:3 to 82: 18, or from 95:5 to 85:15). The random copolymer polyamide for use in the invention more preferably comprises from 87 to 93 wt%, based on the total mass of the copolymer, of first amide monomer units derived from hexamethylene adipamide, tetramethylene adipamide, or combinations thereof, and from 7 to 13 wt%, based on the total mass of the copolymer, of second amide monomer units comprising aromatic and branched aliphatic groups (i.e., 93:7 to 87:13).

[0078] The random copolymer polyamide for use in the invention may comprise about 92 wt%, based on the total mass of the copolymer, of first monomer amide monomer units derived from hexamethylene adipamide, tetramethylene adipamide, or combinations thereof, and about 8 wt%, based on the total mass of the copolymer, of the second amide monomer units comprising aromatic and branched aliphatic groups (i.e., 92:8). This ratio of monomeric units was found particularly advantageous, for example, for random copolymers comprising hexamethylene adipamide as the first monomer units of part i) and 2-methyl-l,5-pentamethylene-isophthalamide as the second monomer units of part ii).

[0079] The random copolymer polyamide for use in the invention is also preferably a copolymer comprising (as part i) first monomer units derived from hexamethylene adipamide and (as part ii) second monomer units derived from hexamethylene terephthalamide, 2-methyl-l,5- pentamethylene-isophthalamide, 2-methyl-l,5-pentamethylene-terephthalamide, or combinations thereof. The random copolymer polyamide for use in the invention is more preferably a copolymer comprising (as part i) first monomer units derived from hexamethylene adipamide and (as part ii) second monomer units derived from hexamethylene terephthalamide and 2- methyl-l,5-pentamethylene-isophthalamide (i.e., is a PA66 / 6T / DI copolymer).

[0080] The PA66 / 6T / DI random copolymer polyamide for use in the invention may comprise 60 to 80wt%, such as 60 to 70wt% of monomeric units derived from hexamethylene adipamide, 25 to 40 wt%, such as 32 to 40wt%, of monomeric units derived from hexamethylene terephthalamide, and 1 to 5wt%, such as 1 to 3 wt%, monomeric units derived from 2-methyl-l,5-pentamethylene- isophthalamide, relative to the total mass of the random copolymer polyamide. The random copolymer polyamide for use in the invention may comprise about 65% of monomeric units derived from hexamethylene adipamide, about 33 wt% of monomeric units derived from hexamethylene terephthalamide, and about 2 wt% monomeric units derived from 2-methyl-l,5- pentamethylene-isophthalamide, relative to the total mass of the random copolymer polyamide.

[0081] The inventors have found that the ratio between the monomer units defined by part i) to the monomer units defined by part ii) may influence the properties of the copolymers. In particular, and without wishing to be bound by theory, the inventors postulate that increasing the amount of the first monomeric units of part i) above that required by the invention may increase the crystallinity of the polymer to provide better the mechanical properties, but also make the crystallization rate too high, so that crystallization occurs whilst the material is being held post- plastificate formation but prior to molding. The inventors also postulate that increasing the amount of the second monomeric units of part ii) to above that required by the invention reduces the rate of crystallization of the material, ensuring that crystallization does not occur whilst the material is being held post-plastificate formation but prior to molding, but affording amorphous products with poor mechanical properties.

[0082] For example, the inventors have found that when the random copolymer polyamides for use in the invention comprises monomeric units of part ii) derived from 2-methyl-l,5-pentamethylene- isophthalamide, or 2-methyl-l,5-pentamethylene-terephthalamide, said monomer units are preferably present in 2wt% to 20wt%. Excess of 20wt% may provide too amorphous materials with crystallization rates that are too slow and less than 2% may provide materials with crystallization rates that are too high. As discussed, controlled crystallization below the melt temperature is required in D-LFT for ease of mold release and good surface appearance or finish.

[0083] Similar results are anticipated for PA66 / 6T / DI copolymers, wherein increasing the amount of DI above that required for the invention will provide materials that too amorphous with crystallization rates that are too slow to provide materials with good mechanical properties.

[0084] Long-Fiber-Reinforced Thermoplastic Composition and Reinforcing Fiber (Roving Material) The method of the invention comprises making a long-fiber-reinforced thermoplastic composition, such as by D-LFT molding, from the random copolymer polyamide composition for use in the invention, wherein the long-fiber-reinforced thermoplastic composition comprises a reinforcing fiber.

[0085] The long-fiber-reinforced thermoplastic composition preferably comprises 20 to 70 wt%, of the random copolymer polyamide composition, based on the total mass of the compounded thermoplastic resin, such as 30 to 70 wt%, based on the total mass of the compounded thermoplastic resin. The compounded thermoplastic resin composition comprises a suitable amount of the reinforcing fiber. The long-fiber-reinforced thermoplastic composition comprises 25 wt% to 60 wt% of reinforcing fiber relative to the total weight of the long-fiber-reinforced thermoplastic composition, such as preferably 25 wt% to 55 wt%, and more preferably 30 wt% to 50 wt%, of reinforcing fiber relative to the total weight of the long-fiber-reinforced thermoplastic composition. It is known in the art that the shear and bending forces employed during molding processes can cause the reinforcing fiber, such as glass fiber, to break and thus shorten in length. The amount of breakage that occurs during molding tends to increase as the loading of the reinforcing fiber (e.g., glass fiber) goes up. The molding of conventional reinforced fiber compositions comprising increased amounts of reinforced fiber (e.g., 25wt% or more) can result in molded articles comprising fibers with a number average length distribution wherein 70 to 80% of the fibers are in the 0.2 to 0.3 mm length range. Methods in the art of maintaining longer fiber length include reducing the content of reinforcing fibers in the fiber reinforced compositions to 20wt% or less.

[0086] Advantageously, the polyamide compositions of the present invention are impregnated with an increased level of reinforcing fiber, i.e., at least 25wt%, which does not undergo significant length reduction during molding. Accordingly, the method of the invention affords long-fiber reinforced polyamide articles comprising at least 25wt% reinforcing fibers wherein at least 25% (e.g. 25 to 68%) of the reinforcing fiber has a length > 0.5 mm, as determined from the number- averaged fiber length. The articles afforded from the method of the invention thus have certain advantageous mechanical properties (particularly good tensile strength, improved elongation to break and improved Charpy notched impact strength). Thus, the present invention provides molding methods, particularly D-LFT molding methods, wherein the compositions exhibit an advantageous combination of relatively higher amounts of reinforcing (e.g., glass) fiber and relatively higher fiber length, which are both important for achieving desirable properties in the reinforced products.

[0087] The reinforcing fiber can include any one or more suitable reinforcing fibers, such as carbon fiber, carbon nano-fiber, short glass fiber, long glass fiber, basalt fiber, natural fiber, mineral fiber, nano-cellulosic fiber, wood fibers, non-wood plant fibers, or combinations thereof. The reinforcing fiber is preferably a glass fiber.

[0088] The reinforcing fibers introduced into the random copolymer polyamide composition during the process of making a long-fiber-reinforced thermoplastic composition of the invention, such as by D-LFT molding, can have any suitable length or length distribution. The reinforcing fiber maybe continuous. Alternatively, the reinforcing fiber may also be dis-continuous. For example, the reinforcing fiber may be cut to a length of between 10 and 50 mm, such as 15 to 30mm, or around 25 mm, before being introduced into the copolymer polyamide composition during the process of making a long-fiber-reinforced thermoplastic composition, such as by D-LFT molding.

[0089] The products afforded from the method of the invention may comprise fibers with a number- averaged distribution that is longer than fibers present in conventional injection molded polyamides. In particular, at least 25% (such as 25-68%) of the reinforcing fibers in the products afforded from the method of the invention may have a length > 0.5 mm, as determined by the number-averaged fiber length. The reinforcing fiber can be glass fibers, wherein at least 25% of the reinforcing fiber has a length > 0.5 mm, as determined via the number-averaged fiber length. The reinforcing fiber present in the fiber-reinforced thermoplastic composition afforded from the method of the invention may have a number-averaged fiber length of up to 50 mm, typically up to 30 mm, or up to 25 mm.

[0090] Additives

[0091] The random copolymer polyamide composition for use in the invention may comprise one or more additives. The additives for use in the invention may be in various physical forms, including, for example, powders, pellets, or masterbatch formulations in a polymer matrix.

[0092] The random copolymer polyamide composition for use in the invention may comprise a flameretardant additive. When present, the flame-retardant additive is preferably incorporated into the random copolymer polyamide composition for use in the invention in an amount of 1 wt% to 30 wt% of the total mass of the random copolymer polyamide composition, such as more preferably 5wt% to 25w%, and even more preferably 10wt% to 21 wt% of the total mass of the random copolymer polyamide composition.

[0093] The flame-retardant additive can include any one or more suitable flame-retardant additives such as halogen-containing flame retardants, halogen-containing flame retardants with synergists, phosphorus-containing flame retardants, inorganic flame retardants, nitrogen-containing flame retardants, nitrogen-containing flame retardants with synergists, or a combination thereof.

[0094] Halogen-containing flame-retardant additives include, but not limited to brominated polystyrene; poly (dibromostyrene); poly(pentabromobenzylacrylate); brominated polyacrylate; brominated epoxy polymer; epoxy polymers derived from tetrabromobisphenol A and epichlorohydrin; Ethylene- l,2-bis(pentabromophenyl); Dechlorane Plus; chlorinated polyethylene; and mixtures thereof. Halogen-containing flame-retardant additives with synergists include, but not limited to the halogen-containing flame-retardant additive together with a synergist, such as but not limited to antimony (III) oxide, antimony (V) oxide, sodium antimonate; iron (II) oxide, iron (II / III) oxide, iron (III) oxide, zinc borate, zinc phosphate, zinc stannate, and mixtures thereof.

[0095] Phosphorus-containing flame-retardant additives include, but not limited to red phosphorus, ammonium polyphosphate, melamine polyphosphate, melamine pyrophosphate, metal dialkylphosphinates (such as but not limited to aluminum methylethylphosphinate, and aluminum diethylphosphinate), aluminum hypophosphite, and mixtures thereof. Inorganic flame-retardant additives include, but not limited to Magnesium Hydroxide, alumina monohydrate, alumina trihydrate, aluminum hydroxide, and mixtures thereof. Nitrogencontaining flame-retardant additives include, but not limited to melamine cyanurate, melamine polyphosphate, melamine pyrophosphate, melamine, melan, and mixtures thereof. Nitrogencontaining flame-retardant additives with synergists include, but not limited to nitrogencontaining flame-retardant additives together with a synergist, such as but not limited to, Novalac resins. Small amounts of polytetrafluoroethylene are often incorporated into the flameretardant additive system to retard dripping.

[0096] The random copolymer polyamide composition for use in the invention may comprise a heat stabilizer. When present, the heat stabilizer is preferably incorporated into the random copolymer polyamide composition for use in the invention in an amount of 0.1 to 2 wt.% of the total mass of the random copolymer polyamide composition. The heat stabilizer is more preferably incorporated into the random copolymer polyamide composition for use in the invention in an amount of 0.5 to 1.5 wt.% of the total mass of the random copolymer polyamide composition. The heat stabilizer can include Cui, KI, or combinations thereof.

[0097] The random copolymer polyamide composition for use in the invention may comprise a colorant. When present, the colorant is preferably incorporated into the random copolymer polyamide composition for use in the invention in an amount of 0.1 to 2 wt.% of the total mass of the random copolymer polyamide composition. The colorant is more preferably incorporated into the random copolymer polyamide composition for use in the invention in an amount of 0.5 to 1.5 wt.% of the total mass of the random copolymer polyamide composition.

[0098] EXAMPLES

[0099] Though primarily directed at a D-LFT (Direct - Long Fiber Thermoplastic, sometimes abbreviated LFT-D) process, and products therefrom, other processes that aid in retaining fibers of length (Long Fibres, LF) within a polymer matrix wherein molten polymer is brought into contact with long or continuous fibers are also envisioned and encompassed within the scope of the application and products so formed, for instance: Pultrusion, organosheets; unidirectional tapes, woven mats, non-woven mats. Moreover, polymer pellets of sufficient quantity may be spread over a woven mat of fibers and heat and pressure applied to melt and force molten polymer to occupy the interstices between the fibers to produce some form of composite sheet.

[0100] Test materials used.

[0101] The terms “nylon-6”, “Polyamide 6”, “PA6”, “N6” are used interchangeably and refer to polycaproamide, which is a homo-polyamide formed from caprolactam.

[0102] The terms “nylon-6, 6”, “Polyamide 66”, “PA66”, “N66”, “nylon 6-6” or “nylon 6 / 6” are used interchangeably and refer to poly(hexamethylene adipamide), which is a polyamide formed by polycondensation reaction between hexamethylene diamine (HMD) and adipic acid (AA).

[0103] PA66 (20-36 RV) refers to a poly(hexamethylene adipamide) having a relative viscosity (RV) of from 20 to 36. Such polyamides are described in International Patent Publication No. WO2019 / 125379A1 and commercially available under the trademark of HYPERFLOW™ Polyamide from INVISTA Intermediates. An example of PA66 (20-36RV) polyamide is a commercially available INVISTA U2501 Grade of Polyamide 66.

[0104] High AEG PA66 refers to a poly(hexamethylene adipamide) having a relative viscosity (RV) of at least 35 or 40 or 45, as determined via a formic acid method, and amine-end group (AEG) range of >65 milliequivalents / kg (meg / kg) and <130 meq / kg, for example, >70 milliequivalents per kg (meq / kg) and <125 meq / kg. The high- AEG PA66 used in the examples has 39 RV and AEG of 92 meg / kg.

[0105] PA66 / DI” refers to a type of co-polyamide formed by combining hexamethylene adipamide salt solution with DI salt solution, where “D” is an abbreviation for 2-methyl-l,5-pentamethylene diamine (also known as MPMD), and “I” is an abbreviation for isophthalic acid that is commercially available. Standard batch evaporation and batch autoclave polymerization processes are used to produce the copolymer. These methods are polymerization processes generally known to the skilled person. MPMD is commercially available under a registered trademark to INVISTA S. a r. 1. as DYTEK® A Amine (CAS Registry Number 15520-10-2). INVISTA DYTEK® A amine is commercially produced by hydrogenating 2- methylglutaronitrile (or “MGN”). MGN is a branched C6 dinitrile obtained as a side-product from butadiene double-hydrocyanation process of adiponitrile (or “ADN”) manufacture. The otherwise disposed MGN side-product can be recycled and reused in the production of INVISTA DYTEK® A amine or the “D” portion; the PA66 / DI produced by this process, therefore, is considered to have the recycled amine content coming from the “D” portion. The “D” containing compounded resins of the present disclosure are considered to contain the recycled amine content.

[0106] PA66 / DI may contain about 80 to 99% PA66 and about 1 to 20% DI on the mass basis, for example, about (on wt:wt basis) 99:1 or 97:3 or 95:5 or 92:8 or 90:10 or 85: 15 or 80:20 for PA66:DI achieved for the salts on dry basis, unless stated otherwise. For clarity a PA66 / DI 92 / 8 copolyamide would comprise 92 wt% PA-66 salt and 8 wt% PA-DI salt, after polymerization the PA-66 residues would constitute about 91.9 wt% and the PA-DI residues about 8.1 w%, on a molar basis PA-66 would constitute about 92.5 m% and PA-DI 7.5 m% which may be rounded to PA66 / DI 92 / 8 m%. The “DI” part in PA66 / DI is about 50:50 (molar) or about 40:60 D:I (mass ratio). PA66 / DI is known as a copolymer of hexamethylene adipamide and 2-methyl-l,5- pentamethylene-isophthalamide.

[0107] As used herein, “PA6I / 6T” refers to a co-polyamide formed by combining a salt of hexamethylene diamine and isophthalic acid, abbreviated as “I”, with that of hexamethylene diamine and terephthalic acid, abbreviated as “T”. PA6I / 6T is also known as a copolyamide of hexamethylene isophthalamide and hexamethylene terephthalamide.PA6I / 6T nylon copolymer is commercially available from EMG-Grivory under the tradename Grivory® G16, G21, and the like. EMS Grivory® G21 nylon copolymer is a medium RV grade of PA6I / 6T (2:1), meaning, 66.6 wt.% of 61 units and 33.4 wt.% of 6T units. EMS Grivory® G16 nylon copolymer is a low RV grade of PA6I / 6T (2:1). Its product information is publicly available at https: / / www.emsgrivory.com / en / ems-material-database.

[0108] In the present disclosure, the term “glass fiber” is abbreviated as “GF” which is understood to be a standard nomenclature in the polymer and compounding industry. The amount of GF in the polymer sample is represented as wt.% of the total, unless stated otherwise. A commercially available TUFRov® 4588 [2400 (g / km)] continuous glass fiber from PPG is used in Examples 1A-1B and 2A-2B. A commercially available TUFRov® 4510 Glass Fiber chopped to 25mm length is used in Comparative Examples A1-A2, B1-B2 and C1-C2.

[0109] Non-limiting examples of various commercially available flame retardant additives may include, BASF Melapur™ MC25 halogen-free flame retardant; Mastertek® antimony trioxide concentrate masterbatches from Campine NV; Clariant Exolit® OP1314 or OP 1400 nonhalogenated organic phosphinate flame retardant; Presafer (Quingyuan) Phosphor Chemical Co. Ltd. Preniphor™ EPFR-MPP300 halogen-free, melamine polyphosphate flame retardant; Albemarle SAYTEX® HP 7010 bromine-based flame retardant; Campine PA 261717 50% masterbatch of antimony trioxide (CAS No 1309-64-4) in Nylon 6; Borax Europe Ltd Firebrake® 500 dehydrated zinc borate based fire retardant, or combinations thereof. A commercially available Exolit® OP 1400 non- halogenated organic phosphinate flame retardant from Clariant is used in the present examples. Test Methods

[0110] Molecular Weight

[0111] Molecular weight of polyamide resins is inferred by measurement of the solution viscosity.

[0112] ASTM D789 is used to measure relative viscosity (RV) of the random copolymer polyamides for use in the invention. ISO 307 using sulfuric acid is used to measure viscosity number (VN). Viscosity values and trends to be considered are determined by the same method, regardless of which method is selected. Measurements are made at standard room temperature (25 °C) and pressure (1 atm).

[0113] Amine end group

[0114] The amine end group (AEG) is measured by titration of polymer solution in phenol / methanol mixture (80:20) with 0.05M perchloric acid in propanol. The end point determined potentiometrically Used interchangeably, the units of AEG are either milliequivalents / kg of sample (meg / kg) or moles per million grams of sample (mpmg).

[0115] DSC - Differential scanning calorimetry

[0116] Melting point (Tm) is the endothermic peak which occurs during heating of samples in a differential scanning calorimeter (DSC) (ISO 11357). Crystallization temperature (Tc) is the exothermic peak which occurs during cooling of samples in a differential scanning calorimeter (DSC) (ISO 11357).

[0117] A Perkin-Elmer DSC analytical instrument was used for measuring the DSC data. About 6-7 mg sample of each test specimen was run, preferably in duplicate, using the following temperature ramp-ups, ramp-downs [rates in °C / min], and isothermal holds [at °C for the stated time in minutes] in between:

[0118] • 1st Heat - heat from 30 °C to 300 °C at 20 °C / min;

[0119] • Isothermal - Hold at 300 °C for 1 min;

[0120] • 1st Cool - Cool from 300 °C to 100 °C at 50 °C / min;

[0121] • Isothermal - Hold at 100 °C for 1 min;

[0122] 2nd Heat - Heat from 100 °C to 300 °C at 10 °C / min;

[0123] 2nd Cool - Cool from 300 °C to 100 °C at 50 °C / min. For each DSC-tested sample, the melt point temperature (Tmor Tm,peak in °C) and Enthalpy change (AHm, Joules / g) were determined from the DSC trace for Heat Flow [endothermic 2nd Heat ramp-up] plotted as a function of the temperature and taken as the maximum rate of melting, the peak of the melting process. The crystallization temperature (Tcor Tc,peak in °C) and Enthalpy Change (AHc, Joules / g) during cooling (crystallization) were determined from the DSC trace for Heat Flow [exothermic 1st Cool ramp-down] plotted as a function of the temperature and taken as the maximum rate of crystallisation, the peak of the crystallisation process. The melting point temperature (Tmin °C), crystallization temperature (Tcin °C) and Enthalpy Change (AH, Joules / g) during data were arithmetically averaged from the two-run measurements when duplicate runs were made.

[0124] Number Average Fiber Length

[0125] The lengths of a number of fibers are measured (using a microscope if required). The number average fiber length is given as:

[0126] Summary of Standards Used

[0127] ASTM D789: formic acid solution relative viscosity (RV).

[0128] ISO 307 using sulfuric acid: viscosity number (VN)

[0129] ISO 527: tensile modulus (MPa) testing of molded and extruded plastics.

[0130] ISO 527: % elongation-at-break testing of materials.

[0131] ISO 179: Charpy impact strength (23 °C, kJ / m2).

[0132] ISO 11357: Differential Scanning Calorimetry (DSC) for melting temperatures and crystallization temperatures of plastics. Ramp rates used are recited herein.

[0133] Test Procedures

[0134] Compounded Feed for the D-LFT Process.

[0135] Methods and apparatus well known in the art, such as twin-screw extruders, may be used to compound additives into the polyamide prior to delivery to the D-LFT process. Additives may be in various physical forms, for instance: powders; pellets; or masterbatch formulations in some polymer matrix. In some examples, the method can include using a twin-screw extruder, such as a Coperion ZSK 26 including two conveying screws, having 26-mm diameter, co-rotating and turning at a suitable speed, such as 300 RPM. The barrel can be heated along its length in zones at temperatures, typically 270-320°C may be used for copolyamides to melt the polymer. The processing section of the Coperion twin screw compounder can be set up to suit various process needs and to allow a wide variety of processes, such as compounding processes. Copolyamide, fillers and additives, as desired, can be continuously fed into the first barrel section of the twin screw using a metering feeder.

[0136] The materials can be conveyed along the screw and get melted and mixed by kneading elements in the plastification section of the barrel. The polyamide composition can then travel along to a side port where, if desired, fillers, such as but not limited to short glass fibers, may be added. The polyamide composition can then pass onto degassing zones, and from there to a pressure build zone where it can then exit the die via holes (e.g., 3 -mm diameter) as a lace. The cast lace can feed into a water bath to cool and to enable it to be cut into chips via a pelletizer.

[0137] In various aspects, the method includes compounding the polyamide with the flame-retardant additive or another additives, such as a masterbatch of heat stabilisers; a masterbatch of colourants; and others well known in the art.

[0138] Injection Molding to aid screening or determination of effects.

[0139] Compounded Feed may be used to make non-D-LFT processed test bars by traditional injection molding for the purpose of screening or determination of effects. The method can include using an injection molding machine (e.g., Demag Sumitomo Sytec 100 / 200) which can include a feed throat, such as a single rotating screw in a temperature zoned barrel, where zones may typically range from 40 to 320°C to melt a copolyamide based resin, and where the screw may move within the barrel to inject a volume of molten resin into a mold, where the mold is typically at 60-90°C for a copolyamide based resin. The mold can yield solid parts or specimens, which can include those suitable for testing, such as, mechanical testing for tensile, impact or flexural physical properties, or to produce flammability bars of desired dimensions. D-LFT Process.

[0140] In a general D-LFT manufacturing process layout, a granulated thermoplastic resin material, such as, the compounded feed or the polyamide itself, along with any other desired additives, is fed to the extruder front and the resultant resin melt is blended with a roving material (e.g.: glass fiber, carbon fiber, natural fibers, etc.) before entering an LFT unit. A non-limiting example of such LFT unit is commercially available Dieffenbacher LFT-D technology [official website: www.Dieffenbacher.com / en / composites / technologies / lft-long-fiber-thermoplast], and for example, Compounder Models Leistritz ZSE 60 GL 24D or Leistritz ZSE 75 GL 22D units. The roving material maybe continuous, for example, PPG’s TUFRov® 4588 [2400 (g / km)] Glass Fiber whose datasheet states a 17-pm filament diameter, and is silane treated and compatible with polyamides.

[0141] In one possible arrangement the resin melt is extruded through a slit die to form a “waterfall or film” of molten resin into which the roving material is introduced and pulled through to coat and wet the roving material before entering the LFT unit. The roving material may also be discontinuous, for example, PPG’s TUFRov® 4510 as a 12-pm filament diameter, silane treated and compatible with polyamides, chopped to 25 mm in length and maybe orientated length ways to feed to the “waterfall” of the resin melt. Within the LFT unit the fiber filled resin is extruded as a thick beam and cut to form a “plastificate”, which may somewhat resemble a “brick” or block of material.

[0142] The LFT extrudate / Plastificate containing the fiber and molten resin portions maybe robotically transported to a conveyer belt and fed into a hot oven for a time before again being robotically transported to a low cycle time profile press for molding into a desired part profile. A nonlimiting example of such profile press is commercially available Dieffenbacher Compress+ [official website: www.Dieffenbacher.com], delivering about 3600 / 3200 ton compression force. The profiled parts maybe robotically transported to the downstream processing section for finished articles, for example, fabrics, sheets, plaques, etc.

[0143] The general parameters used during D-LFT processing the polyamides herein are: 300°C conveyor belt / hot oven temperature, 80°C mold temperature, 60 sec cooling time, 290°C barrel temperature, about 200 RPM screw speed, polymer melt mass temperature in the 280-290 °C range.

[0144] Table 1 below lists some exemplary polyamide test materials used and their material properties [RV, AEG, Tm, Tcand Enthalpies of melting and crystallisation].

[0145] TABLE 1

[0146] *RVF is determined according to the ASTM D789 method [formic acid solution relative viscosity]; RVS [Relative

[0147] Viscosity, 1% in 96% Sulphuric acid]; VNF [Viscosity Number, 0.5% in 90% Formic acid], VNS [Viscosity Number, 0.5% in 96% Sulphuric acid] are determined according to ISO 307 method or principles. RVS uses 1 w / v%.

[0148] #AEG is determined by titration of polymer solution in methanol of phenol. Used interchangeably, the units of AEG are either milliequivalents / kg of sample (meg / kg) or moles per million grams of sample (mpmg).

[0149] Examples 1A-1B:

[0150] Polymer matrix components: 97 parts of Polyamide 1 of Table 1, 1.5 parts of Americhem 48690- 1 (a masterbatch of an antioxidant system of CuI / KI containing 2 w% Cui in PA6) and 1.5 parts of Americhem 9232-F25 (a masterbatch of 25 w% pigmentary carbon black in PA6) were used. Other components: Flame retardant, commercially available under the tradename Exolit® OP 1400 from Clariant AG.

[0151] The above Polymer matrix components and the other components were compounded together in a 70:30 wt% ratio respectively to form a compounded feed for the D-LFT process. The compounded feed was fed to a D-LFT apparatus. The molten polymer formed a coherent “waterfall” into which TUFRov® 4588 [2400 (g / km)] continuous Glass Fiber from PPG was also fed and gave good wetting out of the fiber. Plasitcates were formed, transferred to the hot oven then transferred to a compression mold where the plastificates were formed into simple sheets. Materials with glass fiber contents of 30 wt.% [Example 1A] and 50 wt.% [Example IB] were made and compression molded to 3 mm and 4 mm sheets.

[0152] The sheets were visually determined to have good surface finish.

[0153] Examples 2A-2B:

[0154] Polymer Matrix Component: The Compounded feed of Example 1A-1B that contained 30 wt.% Exolit® OP 1400, together with additional Polyamide 1 of Table 1 was fed to a D-LFT unit such that the concentration of Exolit® OP 1400 was diluted from 30 wt.% to about 20 w%. The molten polymer formed a coherent “waterfall” into which TUFRov® 4588 [2400 (g / km)] continuous Glass Fiber from PPG was also fed. Plasitcates were formed, transferred to the hot oven then transferred to a compression mold where the plastificates were formed into simple sheets. Materials with glass fiber contents of 30 wt.% [Example 2A] and 50 wt.% [Example 2B] were made and compression molded to 3 mm and 4 mm thick sheets.

[0155] The sheets were visually determined to have good surface finish. Table 2 below provides a summary of the components and the levels used in Examples 1 A-1B and Examples 2A-2B.

[0156] TABLE 2

[0157] Comparative Examples A- 1 andA-2:

[0158] Polymer Matrix Component: 69 parts of Polyamide 3 of Table 1 and 29.5 parts Grivory® G21 (PA6I / 6T 67 / 33 mol% from EMS) and 1.5 parts of Americhem 48690-1 (a masterbatch of an antioxidant system of CuI / KI containing 2 w% Cu in PA6) were compounded together to form compounded feed for the D-LFT process.

[0159] The compounded feed was fed to a D-LFT unit. The molten polymer formed a homogeneous “waterfall” into which TUFRov® 4510 Glass Fiber from PPG and chopped to 25 mm length was also fed and gave good wetting out of the fiber. Plasitcates were formed, transferred to the hot oven then transferred to a compression mold where the plastificates were formed into simple sheets. Materials with glass fiber contents of 30 wt.% [Comparative Ex. A-l] and 40 wt.% [Comparative Ex. A-2] were made and compression molded to 4 mm thick sheets.

[0160] In this Comparative Example major parts of two different components were required.

[0161] Comparative Examples B-l and B-2:

[0162] Polymer Matrix Component: 98.5 parts of Polyamide 3 of Table 1 and 1.5 parts of Americhem 48690-were compounded together to form compounded feed for the D-LFT process.

[0163] The compounded feed was fed to a D-LFT unit. The molten polymer formed an inhomogeneous “waterfall” into which TUFRov® 4510 Glass Fiber from PPG, and chopped to 25 mm length was also fed. This inhomogeneous falling film of polymer gave poor even wetting out of the fiber. Plasitcates were formed, transferred to the hot oven then transferred to a compression mold where the plastificates were formed into simple sheets. Materials with glass fiber contents of 30 wt.% [Comparative Ex. B-l] and 40 wt.% [Comparative Ex. B-2] were made and compression molded to 4 mm thick sheets.

[0164] Mechanical testing of samples cut from the sheets in the length direction showed 80% and 63% reduction in terms of % Elongation to break for Comparative Ex. B-l and Comparative Ex. B-2 samples as compared to similar samples cut from sheets made in Comparative Examples A-l and A-2, respectively. Comparative Examples C-l and C-2:

[0165] Polymer Matrix Component: 98.5 parts of Polyamide 2 of Table 1 and 1.5 parts of Americhem 48690-1 were compounded together to form compounded feed for the D-LFT process. The compounded feed was fed to a D-LFT unit. The molten polymer formed a homogeneous “waterfall” into which TUFRov® 4510 Glass Fiber from PPG and chopped to 25 mm length was also fed. Plasitcates were formed, transferred to the hot oven then transferred to a compression mold where the plastificates were formed into simple sheets. Materials with glass fiber contents of 30 wt.% [Comparative Ex. C-l] and 40 wt.% [Comparative Ex. C-2] were made and compression molded to 4 mm thick sheets.

[0166] The appearance of the sheets was poor due to rapid crystallisation of the PA66 at the surface.

[0167] Table 3 below provides a summary of the components and the levels used in Comparative Examples A-l, A-2, B-l, B-2, C-l and C-l.

[0168] TABLE 3 Comparative Examples DI and D2

[0169] Purpose to demonstrate effect of melt processing on thermal transitions.

[0170] DI. 97.5 parts of Polyamide 3 of Table 1, 1.5 parts of Americhem 48690-1 heat stabiliser masterbatch and 1 part Americhem 9232-F25 Carbon Black master batch were mixed and processed on a conventional injection molding machine to produce bars used for tensile testing. DSC analysis found Melt Temperature, Tm (peak) 260°C; Enthalpy of Melting, 44 J / g; Crystallization Temperature, Tc (peak) 218°C; Enthalpy of Crystallization, 63 J / g.

[0171] Comparison to data in Table 1 shows that melt processing has increased the Crystallization Temperature despite the presence of about 2.5 parts of polyamide other than PA66.

[0172] D2. 48.75 parts ofPolyamide 5 of Table 1, 48.75 parts ofPolyamide 3 of Table 1, 1.5 parts of Americhem 48690-1 heat stabiliser masterbatch and 1 part Americhem 9232-F25 Carbon Black master batch were mixed and processed on a conventional injection molding machine to produce bars used for tensile testing. DSC analysis found Melt Temperature, Tm (peak) 255°C; Enthalpy of Melting, 40 J / g; Crystallization Temperature, Tc (peak) 209°C; Enthalpy of Crystallization, 55 J / g.

[0173] Comparison to data in Table 1 shows that melt processing has increased the Crystallization Temperature as compared to either of the two major constituents.

[0174] Comparative Examples El and E2

[0175] Purpose to demonstrate effect of glass fibre incorporation by melt processing on thermal transitions.

[0176] El . 70 parts Polyamide 5 of Table 1 were melt processed on a conventional Twin Screw Extruder to incorporate 30 part of glass fibre. The compounded material was then processed on a conventional injection molding machine to produce short glass fiber filled bars used for tensile testing. DSC analysis found Melt Temperature, Tm (peak) 244°C; Enthalpy of Melting, 41 J / g on polyamide; Crystallization Temperature, Tc (peak) 191 °C; Enthalpy of Crystallization, 53 J / g on polyamide.

[0177] Comparison to data in Table 1 shows that melt processing and presence of glass fiber has increased the Crystallization Temperature.

[0178] E2. 70 parts Polyamide 1 of Table 1 were melt processed on a conventional Twin Screw Extruder to incorporate 30 part of glass fibre. The compounded material was then processed on a conventional injection molding machine to produce short glass fiber filled bars used for tensile testing. DSC analysis found Melt Temperature, Tm (peak) 244°C; Enthalpy of Melting, 43 J / g on polyamide; Crystallization Temperature, Tc (peak) 196°C; Enthalpy of Crystallization, 55 J / g on polyamide.

[0179] Comparison to data in Table 1 shows that melt processing and presence of glass fiber has had little effect on Crystallization Temperature.

[0180] Melt processing typically introduces low level contaminants that increase the Tc. It is postulated that polyamide 1 may have comprised some contaminants (nucleant species) pre melt processing, which is why this polyamide has an initial Tc that is higher than polyamide 5. Polyamide 5 may have been free from contaminants pre melt processing. Therefore, melt processing induces a large increase in Tc.

[0181] Example 3

[0182] Table 4

[0183] 4 mm compression molded sheets were prepared by the D-LFT process with the formulations given in Table 4.

[0184] Test bars were cut and prepared in the lengthways and crossways directions, conditioned to ISO 1110, and mechanical testing conducted according to ISO 527-2 / 1B / 5, the results given in Table 4. Table 5

[0185] In general, the product of Example 3 gave as good as or better properties than Comparative Example 3. Both Example 3 and Comparative Example 3 satisfied the minimum threshold value for tensile strength in the crossways direction of at least 55 MPa, and exhibited comparable tensile strength in the lengthways direction. However, Example 3 exhibited superior Elongation at Break and Charpy impact properties in both directions compared to Comparative Example 3.

[0186] These data demonstrate how the random copolymer polyamide compositions for use in the invention provide D-LFT molding products with improved properties, as compared to comparative methods using compositions comprising a blend of polyamides not satisfying the requirements of the invention (i.e., Comparative Example 3, wherein the random copolymer polyamide comprises only 50wt% of the polyamides present). As discussed, the use of a polyamide blend results in transamidation reactions during the melt phase, varying the melt properties over time, and affording D-LFT molding products with poorer properties.

[0187] Examples 4A and 4B

[0188] Polymer Matrix Component: 98.5 parts of Polyamide 4 of Table 1 and 1.5 parts of Americhem 48690-1 were compounded together to form compounded feed for the D-LFT process. The compounded feed was fed to a D-LFT unit. The molten polymer formed a homogeneous “waterfall” into which TUFRov® 4510 Glass Fiber from PPG, and chopped to 25 mm length was also fed. Plasitcates were formed, transferred to the hot oven then transferred to a compression mold where the plastificates were formed into simple sheets.

[0189] Materials with glass fiber contents of 30 wt.% [Example 4A] and 40 wt.% [Example 4B] were made and compression molded to 4 mm thick sheets. The appearance of the sheets was good.

Claims

CLAIMS1. A method of making a long-fiber- reinforced thermoplastic composition, the method comprising: a) providing a random copolymer polyamide composition comprising a random copolymer polyamide; wherein the random copolymer polyamide comprises: i) from 60 to 99 wt%, based on the total mass of the copolymer, of first amide monomer units derived from hexamethylene adipamide, tetramethylene adipamide, or combinations thereof; and ii) from 1 to 40 wt%, based on the total mass of the copolymer, of second amide monomer units that are different from the first amide monomer units; wherein the second amide monomer units comprise a branched aliphatic group; wherein the random copolymer polyamide is present in the random copolymer polyamide composition in an amount of >80wt% relative to the total amount of all polyamides present in the composition; and wherein the method comprises the steps of: b) heating said random copolymer polyamide composition to afford a melt phase; and c) introducing a reinforcing fiber to the melt phase to afford the long-fiber- reinforced thermoplastic composition; wherein the long-fiber-reinforced thermoplastic composition comprises the reinforcing fiber in at least 25 wt% relative to the total weight of the long-fiber-reinforced thermoplastic composition.

2. The method of claim 1 , wherein the long-fiber-reinforced thermoplastic composition is selected from the group consisting of a fiber-reinforced thermoplastic afforded from a direct long-fiber thermoplastic (D-LFT) molding method, a fiber-reinforced thermoplastic afforded from a pultrusion manufacturing method, an organosheet; a unidirectional tape, a woven mat, and a non-woven mat.

3. The method of claims 1 or 2, wherein the long-fiber-reinforced thermoplastic composition is a fiber-reinforced thermoplastic afforded from a D-LFT molding method.

4. The method of claim 3, further comprising the step of: d) molding the long-fiber-reinforced thermoplastic composition to form a product.

5. The method of claim 4, wherein the product is selected from the group consisting of a fabric, a sheet, and a plaque.

6. The method of claims 3 to 5, wherein the melt phase is extruded through a silt die to form a film of molten resin into which the reinforcing fiber is introduced.

7. The method of any of claims 3 to 6, wherein after step c), the long-fiber-reinforced thermoplastic composition is placed on a conveyor belt and transported to an oven, wherein the conveyor belt and oven are at a temperature of 200 to 400 °C, such as about 300°C.

8. The method of any of claims 4 to 7, wherein step d) comprises introducing the long-fiber- reinforced thermoplastic composition to a mold, wherein the mold is at a temperature of 60 to 120 °C, such as 70 to 110 °C, or around about 80°C.

9. The method of any of claims 3 to 8, wherein the cooling time is from 40 to 100 seconds, such as about 60 seconds.

10. The method of any preceding claim, wherein the second amide monomer units comprise an aromatic group.

11. The method of any preceding claim, wherein the branched aliphatic group is 2-methyl- 1 ,5-pentamethylene.12 The method of any preceding claim, wherein the random copolymer polyamide has a crystallization temperature (Tc) of less than or equal to 200 °C.

13. The method of any preceding claim, wherein the random copolymer polyamide has a crystallization enthalpy of greater than 20 J / g, and preferably greater than 40 J / g.10 July 20244214. The method of any preceding claim, wherein the random copolymer polyamide comprises from 80 to 99 wt%, based on the total mass of the copolymer, of the first amide monomer units; and from 1 to 20 wt%, based on the total mass of the copolymer, of the second amide monomer units.

15. The method of any preceding claim, wherein the random copolymer polyamide is present in the random copolymer polyamide composition in an amount of >85wt% relative to the total amount of all polyamides present in the composition, such as >90wt% relative to the total amount of all polyamides present in the composition.

16. The method of claim 15 wherein the random copolymer polyamide is present in the random copolymer polyamide composition in an amount of >95wt% relative to the total amount of all polyamides present in the composition, such as >97wt% relative to the total amount of all polyamides present in the composition.

17. The method of any preceding claim, wherein the random copolymer polyamide has an amine end group (AEG) value of 30 to 130 milliequivalents / kg (meq / kg), preferably wherein the random copolymer polyamide has an AEG value of 30 meq / kg to 70 meq / kg.

18. The method of any preceding claim, wherein the random copolymer polyamide has a relative viscosity (RV) of from 20 to 50, preferably 30 to 50, when measured at room temperature and pressure, wherein the relative viscosity is measured using an 8.4 wt% polyamide solution in 90% formic acid using ASTM D789.

19. The method of any preceding claim, wherein the first monomer unit is derived from hexamethylene adipamide.

20. The method of any preceding claim, wherein the second monomer units are derived from monomers selected from the group consisting of 2-methyl-l,5-pentamethylene-isophthalamide, 2-methyl-l,5-pentamethylene-terephthalamide, and combinations thereof.SUBSTITUTE SHEET (RULE 26)21. The method of any preceding claim, wherein the second monomer units are derived from 2-methyl-l,5-pentamethylene-isophthalamide.

22. The method of any preceding claim, wherein the second monomer units are derived from hexamethylene terephthalamide.

23. The method of any preceding claim, wherein the random copolymer polyamide is selected from the group of random copolymers consisting of PA66 / DI, PA66 / D6, PA66 / 6I / DT, PA66 / 6I / DI, PA66 / 6T / DT, and PA66 / 6T / DI.

24. The method of any preceding claim, wherein the random copolymer polyamide is the random copolymer PA66 / DI.

25. The method of any preceding claim, wherein the wt% ratio of first monomer units to second monomer units is 97:3 to 82:18; preferably 95:5 to 85:15; and more preferably 93:7 to 87: 13.

26. The method of claims 1 to 23, wherein the random copolymer polyamide is the random copolymer PA66 / 6T / DI.

27. The method of claim 26, wherein the wt% ratio of the PA66 first monomer units to the sum of the 6T and DI second monomer units is 80:20 to 60:40; preferably 70:30 to 65:35; and more preferably 67:33 to 60:40.

28. The method of claims 26 or 27, wherein the wt% of monomeric units derived from hexamethylene adipamide is 60 to 80wt%, the wt% of monomeric units derived from hexamethylene terephthalamide is 25 to 40 wt% and the wt% of monomeric units derived from 2-methyl-l,5-pentamethylene-isophthalamide is 1 to 5wt% relative to the total mass of the random copolymer polyamide.

29. The method of any preceding claim, wherein the random copolymer polyamide composition further comprises a flame-retardant additive, wherein the flame-retardant additive is 1 wt% to 30 wt% of the total mass of the random copolymer polyamide composition.

30. The method of any preceding claim, wherein the random copolymer polyamide composition comprises a heat stabilizer, wherein the heat stabilizer is about 0.1 to 2 wt.% of the total mass of the random copolymer polyamide composition.

31. The method of any preceding claim, wherein the long-fiber-reinforced thermoplastic composition comprises reinforcing fiber in an amount of 25 wt% to 60 wt% of the total weight of the long-fiber- reinforced thermoplastic composition, preferably 25 to 55 wt% of the total weight of the long-fiber-reinforced thermoplastic composition, more preferably 30 wt% to 50wt% of the total weight of the long-fiber-reinforced thermoplastic composition.

32. The method of any preceding claim, wherein the reinforcing fiber is selected from the group consisting of glass fiber such as short glass fiber or long glass fiber; carbon fiber such as carbon nano-fiber; natural fiber such as nano-cellulosic fiber, wood fiber, or non-wood plant fiber; basalt fiber; mineral fiber; aramid fiber, and combinations thereof.

33. The method of any preceding claim, wherein the reinforcing fiber is glass fiber, and wherein 25 to 68% of the reinforcing fiber has a length > 0.5 mm, as determined from the number-averaged fiber length.

34. The method of any preceding claim, wherein the reinforcing fiber is glass fiber, wherein at least 25% of the reinforcing fiber has a length > 0.5 mm, as determined from the number- averaged fiber length.

35. Use of copolymer random copolymer polyamide composition according to any preceding claim for reducing transamidation reactions during formation of a long-fiber-reinforced thermoplastic, wherein the reduction is relative to polyamide blends comprising polyamides each present in an amount of less than 90wt% relative to the total amount of polyamide.

36. The use according to claim 35, wherein the long-fiber-reinforced thermoplastic is a D- LFT.

Images