Extrusion of fiber-containing thermoplastic materials using an extension unit

Abstract

The present invention relates to a method for manufacturing an extruded material, comprising passing a mixture containing a thermoplastic component and fibers through a die and then extruding it through an extension unit.

Description

[Technical Field]

[0001] This invention relates to the production of fiber-reinforced materials using extrusion.

[0002] The present invention relates to a manufacturing process for long-fiber thermoplastic (LFT) extruded materials, preferably a process for manufacturing fluid LFT pellets. The pellets are suitable for molding, such as injection molding. The extruded material and pellets are manufactured using recycled thermoplastic composite (TPC) feed material. The present invention also relates to equipment for the extrusion process. This invention also relates to processes using short fibers.

[0003] Introduction The present invention relates to a process for recycling thermoplastic fiber composite parts into long fiber reinforced thermoplastic parts, for the purpose of recycling long fiber reinforced thermoplastic parts or continuous fiber reinforced thermoplastic parts. Long fiber reinforced thermoplastic components are components that contain long fibers embedded in a thermoplastic matrix. The recycled materials are provided by continuous fiber thermoplastic components used in a wide range of applications, including automobiles and construction. Such components have glass fibers or carbon fibers as continuous fibers, and one or more thermoplastic components. It has been proposed to recycle thermoplastic composite materials by converting them into long-fiber thermoplastics (LFTs), also known as long-fiber reinforced thermoplastics (LFRTs). These are types of easily moldable thermoplastics used to create various components used in the automotive industry. This invention relates to the production of pre-formulated and pelletized LFTs. LFTs are used to manufacture parts by molding (e.g., injection molding and compression molding). In particular, mass production is desirable. Therefore, LFT products can be supplied to units for manufacturing parts, for example, in the form of separate solid pieces such as pellets. The LFT material must be suitable for loading into the unit and it must be possible to load the LFT material into the hopper. LFT pellets produced (recycled) using the method of the present invention may be fluid.

[0004] Potential applications of LFT pellets include, but are not limited to, the manufacture of components for automotive and vehicle dashboards, bumpers and seats, medical equipment components, computer enclosures, building furniture and facade elements, and automotive ski boxes. It can also be used for other purposes.

[0005] Therefore, the present invention relates to a process for producing long-fiber thermoplastic (LFT) materials, and more specifically, to a process for producing LFT extruded material (extruded product) in the form of LFT pellets. Such LFT pellets are 2-25 mm in length, or 5-15 mm in length, with a diameter of 1-10 mm, for example, 1-5 mm, and have a cylindrical shape. Each LFT pellet contains fibers (e.g., carbon fibers, glass fibers, or natural fibers, or other types of fibers) and a thermoplastic polymer.

[0006] The pellets contain fibers having a length of at least 0.3 mm, or at least 0.5 mm, at least 1.0 mm, or at least 2.0 mm, and a maximum length of 50 mm. The fibers have a diameter of at least 1.0 μm, or at least 2 μm, or at least 5 μm, and / or up to 100 μm, or up to 50 μm, or up to 30 μm. The diameter is 1.0 to 100 μm, or 2 to 50 μm, preferably 5 to 35 μm, and more preferably 10 to 25 μm.

[0007] The LFT extruded material produced by the present invention can be used to manufacture a wide range of products, including LFT materials, for example, parts useful for automotive applications, such as door panels, instrument carriers or vehicle front ends, and / or parts useful in other fields such as electronic equipment. In particular, LFT extruded material in pellet form is used as a raw material for molding (e.g., injection molding) to form LFT products. LFT extruded material is cut into pellets, which are then used for molding (e.g., injection molding). In other words, it is desirable that the pellets obtained from cutting the extruded strands be fluid and have a smooth surface. In addition, the pellets should impart good mechanical properties to the articles produced by molding these pellets (e.g., injection molding). Furthermore, a requirement in this technical field is that the pellets have a uniform size, particularly in terms of diameter.

[0008] LFT pellets are often desirable to be fluid for transportation purposes, such as for loading into equipment like hoppers. LFT pellets are fed into molding equipment, such as injection molding equipment. Therefore, the fluidity of the pellets is important for the processability of the material. The fiber length distribution within the pellet is important for product quality.

[0009] Conventional methods for producing LFT pellets include wire coating and extrusion molding. Several prior art documents describe the extrusion process. However, when using discontinuous fibers to manufacture LFT pellets, the resulting extrusions often have a very rough surface, and consequently, the pellets produced from them are found to be non-flowable. In particular, the comparative pellets (PP / carbon fiber) were obtained using a known (reference) extrusion process. The surface of the pellets is very rough and the shape is irregular. Furthermore, the pellets are not fluid. In particular, it has been observed that fibers extend (protrude) from the surface of these reference pellets.

[0010] Therefore, it is desirable to provide a method for preparing LFT extrudates with a better quality surface, regular shape, and good retention of fiber length, and to provide an apparatus suitable for such a method.

[0011] In an embodiment of the present invention, the method of the present invention uses a thermoplastic composite (TPC) feed material as part of the feed for the extrusion process, and the TPC feed material is produced from a CFRT material, for example, by grinding (e.g., shredding) CFRT (continuous fiber reinforced thermoplastic) waste material. Therefore, an embodiment of the present invention relates to the recycling of CFRT waste material into LFT pellets having a smooth surface suitable for molding, for example, injection molding. However, other sources of TPC material, such as short fiber reinforced thermoplastic composites, or fibers recovered from the wind turbine industry are also possible.

[0012] EP3974138A1 describes a method for manufacturing an extrudate of long fiber thermoplastic (LFT), which includes providing a thermoplastic feed material and a thermoplastic composite (TPC) feed material, such as flakes or chips.

[0013] WO2022 / 066021A1 describes a method for manufacturing an extrudate of long fiber thermoplastic (LFT) using an extruder having a first inlet for a thermoplastic material and a second separate downstream inlet opening for a thermoplastic composite feed material.

[0014] US2019 / 0184619A1 describes a method for manufacturing long fiber reinforced thermoplastic filaments, in which a mixture of a fibrous material and a thermoplastic material is introduced through an extended flow die in an extruder to ensure a long fiber length. The extended flow die is a gradually angled convergent die.

Summary of the Invention

[0015] In a first aspect, the present invention provides a method for manufacturing an extruded material, which includes extruding a mixture containing a thermoplastic component and fibers through a die within an extruder. The present invention also provides an extruder and an extrusion device.

[0016] The extension unit in an embodiment of the present invention is configured to cool the strands of the mixture extruded while confining the strands.

[0017] The present invention relates to an extruder including a barrel, a screw, and a die, wherein the die is provided with an extension unit on the outlet side for providing a channel for the flow of the extruded mixture. The channel has a length L c and an average diameter D c over this length L, c and this average diameter D c is at least 0.5 mm, and this length L c is at least 5 times, or at least 10 times, or at least 15 times the average diameter D, c and this channel has a deviation of less than 5% of the diameter from the average diameter D c over the length L. c And the average diameter D is preferably at least 1.0 mm, for example, 1.0 mm to 25 mm, or preferably 1.0 to 10 mm, more preferably 1.0 to 5.0 mm, or 1.0 to 4.0 mm. c

[0018] The present invention provides a method for manufacturing an extruded material, which includes extruding a mixture containing a thermoplastic component and fibers through an extension unit after passing the mixture through a die.

Brief Description of the Drawings

[0019] [Figure 1] A schematic cross-sectional view of the extruder of the present invention is shown. [Figure 2] A schematic example of a system comprising the extruder and cooling tank of the present invention is provided below. [Figure 3] Photographs of strands and pellets manufactured using a comparative extrusion method without extension units are shown. [Figure 4] The image shows a photograph of strands and pellets manufactured using the extrusion method of the present invention with an extension unit. [Figure 5] The image shows photographs of strands and pellets obtained using the extrusion method of the present invention with an extension unit.

[0020] Any embodiments illustrated in the figures are merely examples and do not limit the present invention. [Modes for carrying out the invention]

[0021] This method makes it possible to obtain pellets with improved surface quality and a uniform size distribution, and the pellets are fluid. Surface quality refers to the improved smoothness of the surface. Furthermore, pellets with a uniform cross-sectional size and shape can be obtained.

[0022] The present invention relates to a method for manufacturing extruded material in the form of extruded strands, filaments, or pellets.

[0023] This method involves extruding a mixture containing thermoplastic components and fibers within an extruder. Therefore, this method includes supplying raw materials to an extruder. The extruder is either a single-screw or twin-screw extruder. A single-screw extruder is preferred to maintain fiber length.

[0024] The extruder may have one or more inlets for raw materials. The raw material components may be combined before feeding them into the extruder, or inside the extruder, or in combination thereof, in order to provide a mixture.

[0025] The raw materials include thermoplastic components and fibers. These fibers are provided in a dry state, for example, as fibers not embedded in a thermoplastic material.

[0026] The raw materials include, but are not exclusive, thermoplastic composite (TPC) feeding materials. Generally, TPC feeding material is supplied in the form of separate solid pieces, for example, in the form of flakes or chips. The flakes have a thickness of at least 0.1 mm, for example, up to 5 mm, and a length / width of, for example, 1 mm and / or up to 50 mm. The shape of the feed material is not particularly limited, but the feed material must be suitable for extrusion.

[0027] The TPC feeding material is provided as a collection of separate solid, macroscopic particles.

[0028] The thermoplastic composite (TPC) materials used herein include materials comprising, substantially comprising, or more essentially comprising, thermoplastic polymers and fibers (in a dry state, impregnated, short, long, and continuous, or mixtures thereof). The polymer is a polymer composed of raw material polymers or additives, and the fibers are dry or impregnated, short or long, continuous, or a mixture of such fibers. In embodiments of TPC feeding materials, the fibers are embedded in the thermoplastic polymer if they are fibers impregnated with a thermoplastic polymer.

[0029] Additives are part of a family of antioxidants, UV stabilizers, flame retardants, pigments, dyes, dispersants, adhesion promoters, and, for example, modified polypropylene, especially maleated polypropylene, antistatic agents, release agents, and nucleating agents. The additives may be present in the plastic for recycling, or they may be added to the extruder, or both.

[0030] Furthermore, the material may also contain reinforcing additives, and / or the reinforcing additives may be added to the raw materials. Examples of reinforcing additives include inorganic reinforcing agents such as talc, high aspect ratio talc, mica, glass short fibers, and glass, or organic reinforcing agents such as aramid fibers, polyester fibers, and carbon fibers.

[0031] The raw materials include fibers, such as "long fibers" embedded in a thermoplastic matrix. The fibers have a minimum thickness of 0.5 mm, 1.0 mm, or 2.0 mm, and a maximum length of 100 mm, 50 mm, 10 mm, or 15 mm. The fibers have a diameter of at least 1.0 μm, or at least 2 μm, or at least 5 μm, and / or a maximum of 100 μm, or a maximum of 50 μm, or a maximum of 30 μm. The fibers are glass fibers, carbon fibers, or natural fibers, which can be selected as needed by those skilled in the art, or raw materials having suitable fibers are selected. These lengths and diameters are average values, specifically numerical averages. Each TPC feeding piece contains such fibers embedded in a thermoplastic matrix.

[0032] In the method of the present invention, the average fiber length can be maintained at more than 0.5 mm or more than 1.0 mm during the extrusion step. Maintaining sufficient fiber length can be facilitated by using a low-shear extruder, preferably a low-compression extruder. A method for extruding a suitable composite material with a fiber length greater than 1.0 mm after processing is described in EP3974138, specifically in Example 1 of that document, and in WO2022 / 066020. While we do not wish to be constrained by theory, the presence of at least 0.5 mm or at least 1.0 mm of fibers in the extruded material (e.g., strand) during its release from the die may result in insufficient surface quality of pellets obtained by reducing the size of the material (e.g., strand) using a comparative method that does not employ extension units. However, the presence of a sufficient amount of fibers of such length in the pellet is highly desirable for the downstream use of the pellet.

[0033] In further embodiments, the fibers in the raw material and / or extruded material are shorter fibers. Furthermore, the various advantages of extension units, such as flexibility, are also useful in embodiments where short fibers are used in the raw material. Furthermore, the method of the present invention, which is not only for short fibers with stable and uniform geometric dimensions, can also advantageously achieve high surface quality. Furthermore, it has been observed that the fibers in the extruded material have a fiber length distribution consisting of both shorter and longer fibers. Furthermore, the molten material inside the barrel has a fiber length distribution consisting of both shorter and longer fibers. The method of the present invention is advantageous for embodiments that have long fibers in the raw material and the extruded material.

[0034] Fibers are made from materials different from thermoplastic components. Fibers are not thermoplastic. The fibers either have no melting point or have a melting point above 360°C.

[0035] The raw materials may include two or more types of fibers that differ in one or more of the following: material and fiber dimensions (length and / or diameter). Possible materials for fibers include metal fibers, glass fibers, carbon fibers, boron fibers, ceramic fibers (e.g., alumina or silica), aramid fibers, and synthetic organic fibers (e.g., polyamide, polyethylene, paraphenylene, terephthalamide, polyethylene terephthalate, and polyphenylene sulfide). Furthermore, natural or synthetic inorganic or organic fiber materials can also be used. Glass and carbon fiber are particularly preferred. Furthermore, combinations of glass fiber and carbon fiber are also possible.

[0036] The fibers in the raw material may be twisted or straight. The fibers may be in the form of single fibers or bundles of fibers. The raw material may contain two or more types of granular TPC material, where different TPC pieces contain different types of fibers, or where individual TPC pieces contain different types of fibers.

[0037] Fibers have higher tensile strength than thermoplastic components. Furthermore, this fiber has a tensile strength of at least 1000 MPa, or at least 2000 MPa, or at least 3000 MPa. Conventional measurement methods defined in ISO standards may be used selectively, according to ISO 23523:2021 for polymer fibers, ISO 10618:2004 for carbon fibers, or ISO 9163:2005 (brief method) for glass fibers.

[0038] Fibers have a higher tensile modulus than thermoplastic components. Furthermore, in the case of glass fibers or carbon fibers, these fibers have a tensile modulus of at least 20 GPa, or at least 50 GPa, or at least 100 GPa. Conventional measurement methods defined in ISO standards can be used in accordance with these standards.

[0039] A single type of fiber can be used, or two or more types of fibers can be combined. In the case of different types of fibers, they can be combined beforehand or combined in the extruder.

[0040] The extruded material, i.e., the product, is LFT material (long fiber thermoplastic material). The material comprises, substantially consists of, or more essentially consists of, one or more thermoplastic polymer materials as a matrix and long fibers embedded in this thermoplastic matrix. The fibers of the extruded material are at least 0.5 mm, at least 1.0 mm, or preferably at least 2.0 mm, or at least 3.0 mm, and have an average length in the range of, for example, 1 to 5 mm, for a maximum of 50 mm, or at a maximum of 25 mm, or at a maximum of 10 mm, where the average length is based on the number of particles. These long fibers are embedded in the thermoplastic material within the extruded material. A fiber length of at least 1.0 mm can contribute to good mechanical properties of such components, such as good strength, of components prepared from pellets by molding. Longer fiber lengths can contribute to strength and toughness.

[0041] For example, the fibers are aligned or oriented within the extruded material.

[0042] In both extruded materials and TPC-feeded materials, the polymer is either a raw material polymer, a polymer blended with additives, or a recycled polymer. Recycled polymers are polyolefins, including PP and / or PE.

[0043] Furthermore, the raw materials may include thermoplastic granules or particles, or a combination thereof.

[0044] Furthermore, the raw materials may include dry fibers and fiber fragments (i.e., fibers not embedded in thermoplastic material). For example, fibers recovered from the recycling of wind turbine blades, boats, or PCT boards.

[0045] The various components of the raw material, in particular, the separate solid pieces, can be supplied to a single inlet of the extruder or distributed across one or more inlets of the extruder.

[0046] The ingredients contain less than 5.0% by weight of water, or less than 2.0% by weight of water, or less than 1.0% by weight of water. This can offer a difference from methods using high-moisture raw materials, such as when using (natural) fibers without sufficient pre-drying. Preferably, a drying step is used to obtain a low moisture content in the raw material.

[0047] The TPC feeding material contains at least 20% by weight of fibers, or at least 30% by weight of fibers and less than 80% by weight of fibers. The TPC feeding material contains 30-70% by weight of fibers, or 50-70% by weight of fibers, relative to the total weight of the TPC feeding material. These quantities apply to fibers having a diameter of at least 1.0 μm, or at least 2 μm, or at least 5 μm, and / or a length of at least 2.0 mm, or at least 5.0 mm. In addition, these preferred amounts are applied to synthetic fibers such as glass fibers, carbon fibers, and synthetic polymer fibers. Furthermore, these preferred amounts can also be applied to natural fibers.

[0048] The total raw materials include, in the same manner as above, at least 1.0% by weight of fibers having the length and / or diameter described above, or at least 5% by weight, or at least 10% by weight, or at least 20% by weight, or at least 25% by weight of fibers, for example, up to 60% by weight of fibers, or up to 70% by weight of fibers, as a percentage of the total raw materials. In addition, these preferred amounts are applicable to synthetic fibers such as glass fibers, carbon fibers, and synthetic polymer fibers, and can also be applied to natural fibers.

[0049] In the extrudate, more preferably in the pellets, the fraction of fibers having a length of at least 1 mm is at least 5 wt%, or at least 10 wt%, or at least 20 wt% of the extrudate. The same selection also applies to the raw materials. However, if the raw material contains long fibers with a somewhat reduced size or if the raw material contains short fibers, other sized fibers in the extrudate are also possible.

[0050] The preferably used TPC feed material contains separate solid pieces of the TPC material. The TPC feed material is provided to the extruder as a stream of solid pieces of the TPC material. In the TPC material, the fibers are embedded in the thermoplastic material. The fibers are oriented or aligned in the solid pieces.

[0051] And the raw material includes TPC pieces having a length of 2 mm to 50 mm, a width of 2 mm to 50 mm, and a thickness less than the length and / or less than 5.0 mm, for example, at least 0.1 mm and / or a maximum of 5.0 mm, or a maximum of 4.0 mm, preferably flakes and / or chips. For example, the raw material includes TPC chips having a length (L) of 2 to 50 mm, a width (W) of 2 to 50 mm, and a thickness (H) such that 0.1L < H < L. The TPC flakes have an aspect ratio L / H of at least 10, for example, at least 20. The raw material includes TPC flakes having edges and two side surfaces, and for example, for each such side surface, at least 5 mm 2 or at least 10 mm 2 of surface area. These TPC pieces have an average length of at least 1.0 mm, or at least 2.0 mm, or at least 5.0 mm, and contain at least 10% by weight, or at least 20% by weight, or at least 50% by weight of fibers relative to the total weight of the TPC pieces. For example, the laminate contains 60% by weight of fibers. The average length is a numerical average. In reality, a wide-area distribution of fiber length can be observed. These TPC pieces constitute at least 10% by weight of the total raw material, for example, at least 20% by weight, or at least 30% by weight, or at least 50% by weight, or at least 70% by weight, or at least 90% by weight of the raw material.

[0052] The method of the present invention is particularly advantageous in embodiments in which the raw material comprises CFRT (continuous fiber reinforced thermoplastic) material that has been shredded, crushed, or crushed as TPC pieces, but is not limited thereto. Furthermore, the method of the present invention is also advantageous for dry fibers or a mixture of coated fibers and thermoplastic granules, but as before, it is not limited to these.

[0053] Furthermore, this method includes the step of preparing TPC granules, which are used to provide at least a portion of the raw materials. This step may include grinding (e.g., shredding, crushing) the CFRT (Continuous Fiber Reinforced Thermoplastic) material. Grinding refers to a size reduction step, such as shredding, crushing, or breaking, to produce solid pieces having the minimum dimensions mentioned above. CFRT material is either a thermoplastic composite component that has reached the end of its service life, or it is obtained as production waste from the process of manufacturing CFRT sheet material. Other types of CFRT materials are also possible. The TPC feeding material includes the separated side edges (e.g., trim) of the impregnated fiber layer, such as an impregnated fiber tape or sheet. Such tapes represent an intermediate step in a specific manufacturing method for CFRT materials. Furthermore, the TPC feeding material may include CFRT materials such as CFRT sheets, or chips derived from the reduction in size of CFRT articles such as CFRT automotive parts, for example, by shredding and crushing. Furthermore, various combinations of TPC feeding materials are also possible. CFRT materials are obtained through industrial post-processing such as off-cutting of laminates, or through finishing processes such as overmolding, thermoforming, injection molding, and compression molding of parts.

[0054] In embodiments of the present invention, an optional step for preparing TPC pieces includes providing a plurality of dry continuous fibers to a sheet; impregnating the sheet-like fibers with a thermoplastic resin to produce an impregnated continuous fiber sheet having edges; and separating at least a portion of the edges from the impregnated continuous fiber sheet to produce flake and trimmed continuous sheets.

[0055] These flakes are separated edge fragments, and each flake contains individual fibers and thermoplastic material. The flakes will be used as at least part of the TPC feeding material. The laminate is produced from sheets or tapes, which are optionally trimmed and then cut to reduce their size. The sheets, tapes, or laminates are placed in a mold and subjected to molding (e.g., using heat) to become molded CFRT articles.

[0056] The raw material includes thermoplastic polymer components as components of the TPC feeding material, as separate thermoplastic feeding materials, or as a combination thereof. For this reason, the raw material may include one or more such thermoplastic polymer components, for example, a combination of fibers coated with thermoplastic coatings and thermoplastic granules.

[0057] Thermoplastic polymers are one or more polymers selected from the group consisting of polyolefins, polyamides, polycarbonates, polyphenylene sulfides, polyaryl ether ketones, polyethylene terephthalates, polybutylene terephthalates, polyesters, polyethyleneimines, polyethersulfones, polyoxymethylenes, and polyetherimides. Thermoplastic polymers are polypropylene or polyethylene.

[0058] As used herein, the term "thermoplastic polymer" includes at least plastic polymers that become pliable or moldable at a certain temperature and solidify upon cooling. Furthermore, this thermoplastic polymer is neither crosslinked nor cured. Thermoplastic polymers have a glass transition temperature and / or a melting temperature of less than 400°C, or less than 360°C, or less than 300°C.

[0059] The TPC feeding material substantially contains only one thermoplastic polymer; for example, at least 90% by weight of the thermoplastic portion of the TPC feeding material is a single polymer. Furthermore, the TPC feeding material may include a blend of polymers, or a blend of the same polymer at various stages. Furthermore, the TPC feeding material may include a mixture of TPC granules having different polymer components. Optionally, the polymer or polymer blend of the TPC material is the same polymer or polymer blend used in the first feeding material.

[0060] The thermoplastic components had an MFI of at least 1, or at least 5, or at least 10 g / 10 min, or at least 20 g / 10 min, ideally more than 50 g / 10 min, or even more than 100 g / 10 min, and the MFI was measured according to ISO 1133-1. The thermoplastic component is composed of or comprises at least 50 polyolefins, such as polypropylene, in the MFI. Lower viscosity can contribute to better mixing and improved mechanical properties.

[0061] The raw materials and extruded materials each independently comprise at least 10% by weight, e.g., at least 20%, or at least 40%, and / or up to 95% by weight of a thermoplastic material, such as a polyolefin. The thermoplastic component in the extruded material is the matrix for the fibers.

[0062] The raw materials and extruded materials may contain further components, such as additives, such as friction-reducing additives or flow enhancers.

[0063] The thermoplastic polymer component is provided as a solid piece containing at least 90%, or at least 95% by weight, of the thermoplastic polymer.

[0064] The extruder includes a barrel, a screw (e.g., single-screw or twin-screw), and an outlet opening equipped with dies. The screw provides a channel for the extruder and can be rotated within the barrel. The propeller comprises a cylindrical shaft and flights, typically one or more helical flights. The shaft is positioned in the direction of extrusion.

[0065] Optionally, the barrel comprises a first inlet opening and a second inlet opening, the first and second inlet openings being separated and spaced apart from each other, with the second inlet opening located downstream of the first inlet opening in the extrusion direction. The TPC feeding material is selectively supplied to one or more inlet openings located downstream of the first inlet opening.

[0066] Optionally, the material is fed by a crammer feeder, and optionally, the material is fed in a solid or molten state. The barrel is maintained at temperatures above 100°C, above 150°C, above 200°C, and generally above the melting point of the thermoplastic components. The screw diameter is at least 10 mm, or at least 20 mm, and much larger sizes exceeding 100 mm are also possible.

[0067] This method involves extruding the raw material within an extruder. The raw materials, or a portion thereof, are optionally preheated.

[0068] In one embodiment, the die is a die plate. The die is further provided with a converging channel for the extruded mixture, i.e., a converging channel for the flow of the material being extruded, preferably a tapered converging channel, i.e., a channel that converges or tapers in the direction of extrusion. The die can provide a curved channel, which can contribute to maintaining fiber length. A curved channel refers to a channel that is curved in a cross-section parallel to the extrusion direction, for example, in a cross-section parallel to the screw axis and passing through the screw axis. The channel is curved in the cross-section with a radius of curvature greater than 2.0 mm or greater than 5.0 mm, and this curve of the channel provides at least a 50% reduction in the channel's flow area (the flow area is the cross-sectional area of ​​the channel perpendicular to the extrusion direction). The die has a curved portion, which is optionally used to reduce the flow area of ​​the channel.

[0069] The die has an inlet for the material to be extruded and an outlet for the material. The exit has a smaller cross-sectional area than the entrance.

[0070] The die provides a channel for the extruded mixture in which the cross-sectional area of ​​the channel is typically reduced by at least 50%, more preferably at least 80%, or at least 90% with respect to the cross-sectional area perpendicular to the extrusion direction, for example, the reduction ratio of the cross-sectional area between the inlet and outlet cross-sectional areas of the die is at least 2, or at least 5, or at least 10, or at least 20, or at least 50, or even higher.

[0071] Downstream from the die, there are no restrictions on the cross-sectional area of ​​the passage for the extruded material, and if used, it depends on the size reduction unit (e.g., pelletizer) which is more than 50%, more than 20%, or more than 10% of the cross-sectional area of ​​the die exit. In the case of multiple parallel channels within an extension unit, or otherwise downstream of the die, the cross-sectional area refers to the total cross-sectional area of ​​the channels.

[0072] Any limitations on the flow area of ​​the extruded material within the extension unit are less than 20% or less than 10% of the flow area at the die exit. In other words, the flow area is at least 80% or at least 90% of the flow area at the die outlet over the length of the channel, and is based on the total flow area (the flow area representing the cross-sectional area perpendicular to the flow direction) in the case of parallel channels. Any portion of the channel between the die and the extension unit, and between the extension unit and the size reduction unit, provides a flow area limit of 0-20%. Please note that a certain flow area is included within that range.

[0073] The variation (increase or decrease) in the streamlines of the extruded material from the die to the size reduction unit, or in the flow area of ​​the extruded material in the extension unit, is less than 10% or less than 5% of the flow area at the die exit.

[0074] The relatively constant flow area in the extension unit provides a uniform flow velocity for the extruded material, which is advantageous.

[0075] The die is removably mounted to the barrel using bolts and nuts.

[0076] The die in this invention includes an extension unit, also called an extension member, which is located on the exit side (downstream side) of the die. The extension unit is provided by one or more distinct elements, namely elements distinct from the dice. The extension unit has two or more elements that are different from dice.

[0077] A separate element and an extension unit attached to the die, for example, one mounted on the die, is preferred.

[0078] Specifically, the extension unit is a tubular element. This could allow for easier manufacturing of relatively long channels compared to channels drilled within a die. Furthermore, the separate extension unit enables better L / D control, lower costs, better control of the melting temperature at the outlet (allowing for easy cooling or heating), easier maintenance and assembly, and greater modularity.

[0079] The extension unit provides an extension of the confinement channel for the extruded material, which begins at the die. Therefore, the extension unit provides a conduit (e.g., a tube) for the extruded material, which includes or consists of a wall, for example, a tubular wall. When an extension tube is used, the tube may be provided by one or more parts along its length.

[0080] This method involves extruding the mixture through a die and then through an extension unit. Therefore, the extension unit is located downstream of the die. Furthermore, this extension unit is directly adjacent to the dice. To optimally benefit from the cooling of the extruded mixture in the extension unit, it is preferable to install the extension unit close to the die. The extension unit is configured to cool the mixture from the die, i.e., to cool the extruded mixture, while it is containing the mixture from the die, i.e., while it is containing the extruded material, for example, while it is containing strands of the extruded mixture.

[0081] The extruded material at the entrance of the extension unit is at a temperature higher than the melting point of the thermoplastic component of the extruded material.

[0082] The extension unit is configured to cool the extruded material, for example, one or more strands of an extruded mixture. The extension unit is equipped with channels for the flow of the extruded mixture (the flow path of the extruded material), in particular for the flow of the extruded material (e.g., strands) through the channels (or, more broadly, for the transport of the extruded material through the channels), for example, one channel or two or more parallel channels.

[0083] Therefore, the extension unit may be provided as one or more ducts for the extruded material. A duct consists of a channel and a duct wall, which is also called a channel wall.

[0084] If the extension unit has a single inlet and multiple outlets for the extruded material, the extension unit may include a manifold for distributing the extruded mixture into multiple parallel channels. Alternatively, the extruder may have multiple extension units arranged in parallel, each extension unit being, for example, a tube having a single channel.

[0085] In a cross-section perpendicular to the flow direction, the channel has a convex shape; that is, considering any two points in the cross-section, the cross-section of the channel includes the entire line segment connecting them. For example, the cross-section may be circular or have another shape.

[0086] As used herein, the term “flow” of an extruded material includes both the transport of the extruded fluid mixture and the transport of partially or completely solidified strands of the extruded material. Furthermore, when used herein as an exemplary type of extruded material, the extruded strands include both solidified extruded strands and unsolidified or partially solidified extruded strands. When used herein, the extruded material includes material being extruded and material that has already been extruded. The extension unit's channel includes a wall that completely contains the extruded material (strands of extruded material) around its perimeter.

[0087] The extruded material is partially or completely solidified within the extension unit by cooling. At least the surface of the extruded material solidifies within the extension unit. At least the surface of the extruded material (e.g., strand) reaches a temperature below the melting point of the thermoplastic component in the channel of the extension unit. At least the surface of the extruded material (e.g., strand) reaches a temperature in the channel of the extension unit that is at least 5°C, or at least 10°C, or at least 20°C, or even at least 30°C below the melting temperature of the thermoplastic component. In the case of a blend, the melting point is lower than that of the thermoplastic component with the lowest melting point.

[0088] Confining the extruded material within the channel of the extension unit can help avoid deformation of the extruded material surface due to fiber protrusion.

[0089] In at least the upstream portion of the channel (for example, 10% upstream of the channel length, or 90% upstream of the channel length), the wall is in contact with the extruded material around its entire circumference, and more preferably, the wall is in contact with the extruded material along the entire length of the channel. This allows the wall to contain and secure the extruded material. The wall may include a surface coating exposed to the extruded material, such as a surface coating on the channel.

[0090] The extruded material is at a temperature above the melting point of the thermoplastic component at the die exit and the extension unit inlet.

[0091] This method involves cooling the extruded mixture while it is passing through the channel, and consequently, cooling the extruded mixture (e.g., strands) while it is confined within the channel. Although we do not wish to be constrained by theory, this may allow for sufficient solidification of the extruded mixture while the mixture is radially constrained within the channel by the channel walls, thereby preventing undesirable deformation of the extruded material after it is released from the extruder.

[0092] The extension unit comprises one or more tubular elements, which provide a channel. The channel is straight to avoid deformation of the extruded material (e.g., strand). Specifically, the channel does not have any bends in the longitudinal direction (axial direction). The diameter of the channel may be constant over the length of the channel, or it may vary. For example, a channel converges in the direction of flow in its upstream portion and maintains a constant diameter throughout its downstream portion.

[0093] In broad embodiments of the present invention, the channel geometry is not particularly limited in combination with cooling. The specific preferred geometry of the channel is as described below. As shown in the examples, good results have been obtained for such channels.

[0094] The channel has a length of at least 5 times, or at least 10 times, or at least 20 times, or at least 30 times, or at least 40 times the diameter of the channel. The channel diameter refers to the inner diameter of the tube if the channel is provided by a tube. This relatively high ratio of length to diameter can contribute to sufficient cooling of the extruded material within the channel, thereby contributing to dimensional control of the output extruded material, such as strands. A higher ratio of length to diameter (L to D) may be beneficial in obtaining higher quality extrusions. A higher L / D ratio (e.g., an L / D ratio of at least 30) is particularly useful for carbon fibers. For glass fibers, it was found that an L / D ratio within the range of 10 to 40 yielded good results. Example 3 demonstrates excellent surface quality achieved with a high L / D value, combined with the high thermal conductivity of the tube used as an extension unit.

[0095] Using tubes or pipes in extension units allows for a higher L / D ratio and the use of relatively smaller diameters compared to drilled or machined metal pieces. Such an L / D ratio was found to yield good results (see Examples). A diameter that is not too large is advantageous for the size of the pellets and strands, and tubes having such an inner diameter can be used.

[0096] Channel diameter, especially average diameter D c It is at least 0.5 mm or at least 1.0 mm, for example, less than 50 mm, or less than 40 mm, or less than 30 mm, or less than 20 mm, or less than 10 mm.

[0097] For example, average diameter D c The diameter is 1.0 mm to 25 mm, preferably 1.0 to 10 mm, and more preferably 2.0 to 5.0 mm. average diameter Dc This is the average diameter over the length of the channel.

[0098] Diameters within these ranges are particularly useful for producing pellets that can be used in (injection) molding and for using extruded materials for additive manufacturing. These diameters are the average diameter D of the channel. c It is combined with a channel having a length at least 5 times, or at least 10 times, or at least 20 times longer than the given length. The channel has a circular cross-section. If the channel has a non-circular cross-section, the diameter refers to the equivalent area diameter.

[0099] The channel has a length of at least 2.5 mm, or at least 3 mm, at least 5 mm, at least 10 mm, or at least 20 mm, or at least 50 mm, or at least 100 mm, and optionally less than 50 cm, or less than 20 cm.

[0100] The channels of the extension unit typically have a substantially constant diameter over the length of the channel, which is within the range described above. In this specification, substantially constant means a deviation of less than 20%, less than 10%, less than 5%, more preferably less than 1%, from the average diameter of the channel over that length.

[0101] The channel has a convergence angle that, on average over the length of the channel, is in the range of 0° to 10° or 0° to 5°. The channel has a convergence angle within the range of 0° to 10° or 0° to 5° at any point along the longitudinal 50% downstream of the channel, or along its entire length.

[0102] The flow area of ​​each channel is 80% or more, preferably in the range of 80-120%, of the flow area at the channel inlet at any point along the length of the channel.

[0103] This method involves cooling the extruded mixture while it is passing through the extension unit, specifically, while it is passing through the channels of the extruded mixture strands, for example. Cooling is performed by indirect heat exchange with a cooling fluid (liquid or gas), more preferably by forced flow of the cooling fluid. The cooling fluid is optionally a gas. The cooling fluid is a liquid intended for cooling, at least at the inlet of the extension unit. Indirect heat exchange indicates that the extruded material (e.g., strand) and the cooling fluid are in contact with different sides of the conduit wall (channel wall). Therefore, indirect heat exchange occurs through the channel walls. During operation, the extruded mixture is in contact with the inner surface of the wall, while the cooling fluid is in contact with the outer surface of the wall. For example, the outer surface of the wall is in contact with the outside air or coolant during operation.

[0104] In a further embodiment, the method includes cooling the extruded mixture while it is passing through the extension unit, specifically, while the extruded mixture is passing through the channels of strands of the extruded mixture.

[0105] The extruder further comprises a cooling unit having an inlet and outlet for a fluid, such as a cooling fluid (refrigerant), for cooling the extruded mixture as it passes through the extension unit, and at least some of the channels for the extruded material of the extension unit, i.e., chambers for receiving a fluid (e.g., a cooling fluid) that is in indirect heat exchange contact through a heat exchange wall. In embodiments involving heating of the channel, the fluid is a heating fluid. In general, fluids can be used as heat transfer fluids.

[0106] The (cooling) fluid and the extruded material are separated from each other to prevent mixing. The chamber for the fluid is provided as an annular band around the wall of the flow path of the extruder. Therefore, the extruder may be equipped with a conduit for fluid. The extruder may be configured to use a fan, compressor, or pump to force the flow of heat transfer fluid through the cooling unit.

[0107] In embodiments involving cooling using a cooling fluid, the cooling fluid has a temperature lower than the melting temperature in the extruder, preferably at least 50°C lower or at least 100°C lower, at least at the inlet of the cooling unit.

[0108] The heat exchange wall, or alternatively the channel wall, is made of metal and has a thickness of, for example, less than 5 mm, less than 2 mm, or less than 1.0 mm. Thin walls contribute to effective heat exchange with the fluid.

[0109] Therefore, as a general preference, with or without active cooling, the channel walls are made of metal and have a thickness of, for example, less than 5 mm, less than 2 mm, or less than 1.0 mm. Thin walls contribute to effective heat transfer from the extruded material through heat exchange with the atmosphere or cooling fluid.

[0110] In general, with or without optional active cooling, the channel walls may include two or more materials, for example, a metallic portion and a non-metallic portion, or two types of metallic portions. Generally, a metal channel wall includes a metal portion, and more preferably, a metal tube portion, such as a cylindrical metal tube portion. For example, coated tubes, bimetallic tubes, and pipes can be used.

[0111] The extension unit comprises a pipe or tube, or is a pipe or tube, the pipe or tube providing a channel for the extruded material. The pipe or tube is made of metal and is, for example, cylindrical. Preferably, both the inner and outer surfaces of the tube are cylindrical. Therefore, the extension unit is equipped with a metal pipe or tube that receives the extruded material during operation. Pipes or tubes are manufactured using hot rolling or cold rolling, or using a hot extrusion process, or using a hot hollow forging process. Additionally, a tube extraction tool can also be used.

[0112] The extension unit is flexible. The flexibility of extension units, such as pipes or tubes, can be used to provide curved extension units, such as downward-curved extension units. Curvature refers to the curvature in the length direction, for example, a tube that is not straight in the length direction but curved in the length direction. The longitudinal direction is the direction of flow of the extruded material within the channel. This can be used to guide the extruded material from the horizontal extruder to the cooling tank. For example, the extruded material after exiting the extension unit enters a cooling tank, specifically, the extruded material enters the liquid in the cooling tank through the horizontal gas-liquid interface of the liquid. Bending the extension tube or pipe downwards is advantageous for the rapid transfer of the extruded material into the liquid. The extruded material is immersed in a liquid in a cooling tank for effective cooling.

[0113] The extruder is preferably connected to the tip of the flexible extension unit and includes a connecting element configured to apply tension to the flexible extension unit or to bend the unit. The connecting elements are also connected to the frame or the extruder. The connecting elements are, but are not limited to, positioned to bend the flexible extension unit (e.g., a tube) downwards. The connecting element is particularly useful in the case of elastic tubing. The extension unit's tubing can also be bent during manufacturing.

[0114] The extruder is part of an extension system, which further comprises a cooling tank, such as a water tank, with an inlet for the extruded material on the top surface of the cooling tank. The cooling tank is positioned to receive the extruded material from the extension unit of the extruder during operation.

[0115] Furthermore, the flexible extension unit is also advantageous in the case of an extruder that has multiple extension units independently. The flexible tube used as an extension unit can be bent to allow for stacking multiple extruded strands.

[0116] For example, metals with a relatively low Young's modulus (lower than, for example, carbon steel), such as bronze, copper, titanium, or aluminum, are used to have a low flexural modulus.

[0117] Furthermore, tubes having thin walls can be used to provide flexibility to the tube, for example, a wall thickness of less than 1.0 mm or less than 0.50 mm.

[0118] In general, extension units can include curved tubes, regardless of the flexibility of the tubes. For example, an extension unit can be provided using a rigid, curved tube.

[0119] The use of one or more tubes as extension units also provides the possibility of forming channels and flexibility after manufacturing. In the case of an ultra-thin-walled extension tube, flexibility is possible and easy before and after attaching the extension nozzle. In the case of thick-walled tubes, flexibility is preferably provided before the extension nozzle is attached, but it is also possible afterward.

[0120] The flexibility of extension units, such as tubes, provides the possibility of controlling the orientation and velocity of material flow. This then provides good stability and control to the manufactured extruded material (e.g., extruded strands). Flexibility can be the shape and form of a single, simple curve, or a double or more curved shape. This provides advantages in manufacturing, such as greater controllability and flexibility. For example, a single nozzle can control the shape, velocity, and direction of the material flow. In a dual or multi-nozzle configuration (multiple extension tubes in parallel), the shape of the material, the flow velocity of each strand, and the flow direction can be controlled independently. Another embodiment involves, for example, the material being directed into a cooling tank (cooling unit) at a desired different inlet angle. Another advantage of flexible and / or tubular extension tubes is that they facilitate external cooling or heating of the nozzle. Furthermore, this advantage can also be obtained with thin-walled straight tubes as part of an extension unit.

[0121] The wall must be at least 100Wm -1 K -1 (W / (m·K)), or at least 200Wm -1 K -1 , or at least 300W·m -1 K -1 The material having the thermal conductivity of, for example, a metal or alloy, is at least partially made of, and the thermal conductivity was measured according to ISO 8302, in particular ISO 8302:1991.

[0122] For example, the channel walls are made of copper, or aluminum, or tungsten, or silver, or one or more of these metallic elements, for example, at least part of an alloy including a certain type of brass and aluminum alloy. Therefore, the extension unit is provided by one or more tubes made of at least a portion of such a material (metal or alloy) having high thermal conductivity.

[0123] High thermal conductivity contributes to sufficient cooling within the channel. The advantages of using tubes with high thermal conductivity are demonstrated in Example 3, including excellent surface quality of the extruded strands even without active cooling of the walls.

[0124] The extension unit is provided by one or more tubes, each containing a tubular portion made of such metal or alloy and preferably having a thickness of less than 5.0 mm. Direct contact between the thermally conductive tube portion and the extruded material is not necessary in the case of tubes with an inner surface or a bimetallic tube coating.

[0125] The extruded material at the end of this extension unit is in the form of strands or filaments. The filament contains continuous strands.

[0126] It was observed that the extruded material received from the extension unit had a desirable uniform size, for example, a uniform diameter for each strand / filament.

[0127] This method optionally further includes reducing the size of an extruded material (e.g., a strand) in a size reduction unit, preferably into pellets. The size reduction unit is a cutter.

[0128] Size reduction may include pelletizing or cutting extruded material, such as strands. The length of the pellets or pieces is 10-15 mm. The diameter of the manufactured pellets is at least 2.0 mm, or at least 3 mm, and / or up to 8 mm. Generally, the diameter of the pellets or cut pieces is 90-110% of the diameter of the strand used in the size reduction device, cutter, or pelletizer inlet.

[0129] Therefore, the present invention also provides an extrusion apparatus (system) comprising an extruder as described and a size reduction device for reducing the size of the extruded material (strands of extruded material) from an extension unit to form pellets. The device used for reducing the size of a pelletizer is a pelletizer. A size reduction device is a cutting device. This device is positioned next to the extruder.

[0130] Extruded material (e.g., strands) is used as a filament for additive manufacturing, such as fused deposition modeling. In such embodiments, essentially continuous extruded strands can be used in this way without requiring size reduction, particularly through pelletization, and can be rolled, for example. Therefore, the use of pellets is not limited to molding.

[0131] Furthermore, the pellets can also be used for other purposes, such as additive manufacturing. Extruded materials, such as pellets, can be used in the additive manufacturing of polymers, fibers, particles, and fiber-reinforced materials. For example, extruded materials can be used in molten particle production (FPF) and fused granule production (FGF). Molten particle production involves layer-by-layer deposition of extruded material to create a three-dimensional object, and the extruder receives the particles or granular material. A mobile extruder is used to deposit extruded material according to a pattern. Plastic granules (also called plastic pellets) are extruded, specifically melted and fed through an extruder equipped with a nozzle, which moves horizontally for each layer and vertically to create the next laser. Exemplary processes are described by Nieto et al, Additive Manufacturing 23, 2018, pages 79-85, https: / / doi.org / 10.1016 / j.addma.2018.07.012, and by Woern et al, Materials 2018, 11, 1413; doi:10.3390 / ma11081413.

[0132] This method further includes, along with additional components, producing molded articles from raw materials including an extruded material by molding pellets, for example by injection molding pellets. Furthermore, other types of molding, such as extrusion molding and compression molding, are also possible.

[0133] The present invention also provides a method for producing molded LFT parts, preferably injection-molded LFT parts, wherein the method comprises preparing pellets using the extrusion method and pelletizing step of the present invention, and subjecting the obtained pellets to molding (preferably injection molding) to produce LFT parts. LFT components are specifically molded parts.

[0134] The die is modular and includes means for removably mounting the die to the barrel of the extruder. The extruder is equipped with means for releasably attaching an extension unit to the die, which means being screws or nuts and bolts.

[0135] The fiber length, when used in this specification, can be determined, for example, by an optical microscope. The average or average fiber length refers to a numerically weighted average.

[0136] Figure 1 illustrates a cross-sectional view of the extruder (1) of the present invention, which includes a barrel (not shown), a screw (not shown), and a die (2). The convergence channel within die(2) is curved. The die (2) is located on the outlet side and includes an extension unit (3) that provides two parallel channels for the flow of the extruded mixture. The extension unit (3) is provided by two parallel tubes. The extruder (1) further comprises a cooling unit (4) (optionally used) having an inlet and outlet for a cooling fluid and a chamber for cooling the fluid that is in indirect heat exchange contact with the extruded material within the channel of the extension unit (3). The cooling unit (4) can slide relative to the extension unit (4) from an upstream position close to the die (2) to a downstream position close to the tip (as illustrated). The cooling unit (4) is provided by two tubular elements separated from the die (2).

[0137] Figure 2 schematically shows an embodiment that has a flexible extension tube. The reference symbols are the same as in Figure 1. The extruder (1) is equipped with a die (2) having a flexible tube (3) as an extension unit. The extruded material exits the tube and enters a cooling tank (5) filled with coolant. The extruder (1) optionally includes connecting elements (not shown) for bending a flexible tube and thereby curving the tube downward. Optional connecting elements are connected to both the tube and the extruder (1), or to a frame not shown. Therefore, a system comprising an extruder (1) and a cooling tank is shown.

[0138] Figure 3 shows photographs of strands (A) and pellets (B) manufactured using a comparative extrusion method without the extension unit (3).

[0139] Figure 4 shows photographs of strands (A) and pellets (b) manufactured using the extrusion method of the present invention with extension unit (3). The surface quality is significantly higher (smoother surface) than that obtained using the comparative method. The pellets of the present invention were fluid. Furthermore, it was observed that strands and pellets prepared using the method of the present invention exhibited improved geometric and dimensional quality. [Examples]

[0140] Herein, the present invention is further illustrated by the following non-limiting embodiments. These embodiments do not limit the present invention.

[0141] Example 1 Experiments were conducted using an extension unit (3) as illustrated in Figure 1, with or without active cooling using a cooling unit (4). Table 1A shows the details of the cooling system, including whether or not cooling is performed, the location of the cooling unit (4) (downstream tip T, midstream M, upstream B), and the cooling temperature. The cooling temperature was measured on the outer surface of the extension unit (3). The barrel temperature was 180°C, 230°C, or 250°C. In this embodiment, the extension unit (nozzle) was provided by two parallel tubes with an inner diameter of 3 mm and a length of 100 mm. Therefore, L / D was 33. The tube was made of steel, and its wall thickness was 2 mm. The raw material was 40% by weight of long glass fiber reinforced PP. The results shown in Table 1B indicate that, with a 3 mm nozzle extension, the average fiber length of the pellets remains acceptable, the pellets are fluid, and therefore the pellets are easily fed into a molding machine, such as an injection molding machine. Pellets produced with the cooling unit (4), and pellets produced without the cooling unit (4), achieve the specified targets.

[0142] Table 1B shows the median measured fiber length, the standard deviation of the mean length, and the median fiber length (geodetic fiber length at 50% of the counted objects) in the pellets, as well as the fiber fraction (by weight %) (determined by ashing the matrix and weighing the residual fibers), the diameter of all pellets, and whether the pellets are fluid or not. [Table 1] [Table 2]

[0143] Example 2 Further experiments were conducted using 40% by weight long glass fiber reinforced PP. The extension unit (3) has a length (nozzle) of 60 mm or 100 mm, an inner diameter of 3 mm, and two parallel extension units (3) were used (see Table 2A). This embodiment illustrates that fluid LFT pellets can also be obtained with extension units of different lengths (3), specifically with shorter tube lengths than in Example 1, and at different barrel temperatures (see Table 2B).

[0144] In the case of sample P, cooling using the cooling unit (4) was performed at the upstream position B and at a cooling temperature of 95°C. [Table 3] [Table 4]

[0145] Example 3 The experiment was carried out using an extruder (1) equipped with an extension unit (3). The copper tubes were used as extension units (3) using carbon fiber and polypropylene (PP) polymer without active cooling. The tube was flexible. The extruded strand was released from the tube into the tank. Details and results are shown in Tables 3A and 3B. The average fiber length is the average weighted average.

[0146] The tubing of extension unit (3) was exposed to the outside air. The copper tubes were flexible, with lengths of 155 mm or 260 mm, inner diameters of 3 mm or 4 mm, and tube L / D ratios of 39, 52, or 65. The wall thickness was 1 mm. The temperature of the outer surface of the tube at the tip and at half the length of the tube was measured for Experiments 1 and 2. The fiber content was approximately 30% by weight. The fiber length in the product (manufactured pellets) was within a favorable narrow range of 0.8 to 1.0 mm. The pellets possessed excellent surface quality (very smooth), fluidity (excellent flow characteristics), and, advantageously, a very narrow diameter tolerance.

[0147] Figure 5 shows typical chains (A) and pellets (B) obtained in this embodiment, which have very smooth surfaces and therefore excellent surface quality. [Table 5] [Table 6]

Claims

1. A method for manufacturing extruded material, The process involves passing a mixture containing thermoplastic components and fibers through a die in an extruder, and then extruding the mixture through an extension unit configured to cool the extruded mixture while the extruded material is confined. The aforementioned extruded material is a strand, A method wherein the extension unit comprises a channel and a wall for the channel.

2. The extruded material solidifies at least partially while it is confined within the channel of the extension unit, The method according to claim 1, wherein at least the surface of the extruded material is solidified within the extension unit.

3. The method according to any one of the prior claims, further comprising reducing the size of the extruded material to form pellets.

4. The method includes supplying a raw material containing a thermoplastic composite (TPC) feeding material to the extruder. The TPC feeding material includes TPC pieces, The method according to any one of the prior claims, wherein the TPC piece comprises a fiber and a thermoplastic material, respectively.

5. The extruded material contains fibers, The method according to any one of the prior claims, wherein the fraction of fibers having a length of at least 1 mm is at least 5% by weight of the extruded material.

6. The method according to any one of the prior claims, comprising cooling the extruded mixture by indirect heat exchange with a forced-flow cooling fluid, preferably a coolant, as the mixture passes through the extension unit.

7. The extension unit comprises the channel, The channel is for the flow or transport of the extruded mixture, The channel has a length L ｃ and the length L ｃ Average diameter D ｃ It has, The average diameter D ｃ However, it is at least 0.5 mm, The aforementioned length L ｃ is the average diameter D ｃ It is at least five times that, The aforementioned length L ｃ is the average diameter D ｃ The method according to any one of the prior claims, wherein the amount is at least 10 times, or at least 20 times, or at least 30 times.

8. where the channel has an average diameter D ｃ over the length L ｃ with a deviation of less than 5% of the diameter from, the method according to claim 7

9. The method according to any one of the prior claims, wherein the wall has a thickness of less than 5 mm.

10. The aforementioned wall has at least 100 W·m －１ ・K －１ (W / (m*K)), or at least 200 W·m －１ ・K －１ , or at least 300 W·m －１ ・K －１ A material having a thermal conductivity such as, for example, a metal or alloy, at least partially made of, The method according to any one of the prior claims, wherein the thermal conductivity is measured in accordance with ISO 8302.

11. - The wall has a thickness of less than 5 mm, - The channel has a length L ｃ , and the length L ｃ Average diameter D ｃ It has the average diameter D ｃ However, it is within the range of at least 0.5 mm, and the length L ｃ is the average diameter D ｃ It is at least 10 times that, - The wall has a minimum of 100 W·m －１ ・K －１ The method according to claim 1, wherein the material is at least partially made of a material having a thermal conductivity of (W / (m*K)).

12. The method according to any one of the prior claims, wherein the extension unit comprises a tubular element, preferably a tube, that provides the channel.

13. The method according to claim 12, wherein the tubular element is curved in the longitudinal direction of the tube.

14. A method for manufacturing molded LFT parts, A method comprising preparing pellets using the method of claim 3, wherein the preparation of the pellets has the characteristics described in any one of claims 4 to 13, and molding, preferably by injection molding, the pellets.

15. An extruder (1) comprising a barrel, a screw, and a die (2), The die is provided with an extension unit (3) on the outlet side that provides a channel for the flow of the extruded mixture, and the channel has a length L ｃ , and the length L ｃ Average diameter D ｃ It has the average diameter D ｃ However, it is at least 0.5 mm, and the length L ｃ is the average diameter D ｃ It is at least five times, preferably, - The channel of the extension unit has a wall having a thickness of less than 5 mm, and / or - said average diameter D ｃ However, it is at least 1.0 mm, for example 1.0 to 10 mm, more preferably 1.0 to 5.0 mm, and / or - The channel has the length L ｃ The average diameter or thickness D over the said area ｃ Having a deviation of less than 5% from the diameter or thickness, and / or - The aforementioned length L ｃ is the average diameter D ｃ At least 10 times, or at least 20 times, or at least 30 times, and / or - An extruder in which the extension unit comprises a tubular element, preferably a tube, that provides the channel.

16. The extruder according to claim 15, further comprising: a cooling unit (4) having an inlet and outlet for a cooling fluid, for cooling the extruded mixture as the mixture passes through the extension unit; and a chamber for receiving the cooling fluid, which is in indirect heat exchange contact with at least some of the channels for the extruded material of the extension unit.

17. - The channel of the extension unit has a wall having a thickness of less than 5 mm, - said average diameter D ｃ However, it is at least 1.0 mm, for example 1.0 to 10 mm, more preferably 1.0 to 5.0 mm, and - The aforementioned length L ｃ is the average diameter D ｃ The extruder according to claim 15 or claim 16, wherein the amount is at least 10 times, or at least 20 times, or at least 30 times.

18. The extruder according to any one of claims 15 to 17, wherein the channel of the extension unit has a wall having a thickness of less than 2 mm, or preferably less than 1.0 mm.

19. The aforementioned wall has at least 100 W·m －１ ・K －１ (W / (m*K)), or at least 200 W·m －１ ・K －１ , or at least 300 W·m －１ ・K －１ It is made at least partially from a material having a thermal conductivity, such as a metal or alloy. An extruder according to any one of claims 15 to 18, wherein the thermal conductivity is measured in accordance with ISO 8302.

20. The extruder according to any one of claims 15 to 19, wherein the extension unit comprises a tube, the tube being curved in the longitudinal direction of the tube.

21. An extrusion apparatus comprising an extruder according to any one of claims 15 to 20, The extension unit is further equipped with a size reduction device for reducing the size of the strands of extruded material to form pellets. The aforementioned size reduction device is an extrusion device, which is a cutter.

22. The method according to any one of claims 1 to 14, carried out in an extruder or extruder according to any one of claims 15 to 21.

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