Method of manufacturing a lightweight structurally reinforced thermoplastic material object

Abstract

A method of manufacturing a lightweight, structurally reinforced thermoplastic material object, the object comprising at least one reinforced zone, the method comprising providing a heatable rigid forming chamber (2) having a chamber volume (V). At a base temperature below a thermoplastic softening temperature, the chamber is loaded with a plurality of thermoplastic loft bodies (12a, 12b, 12c, 12d, 12e, 12f) and a plurality of thermoplastic reinforcement bodies (14a, 14b, 14c, 14d, 14e, 14f). The loft bodies are: i) heatable loft bodies comprising a thermoplastic matrix containing an elastically compressible assembly of reinforcing fibers embedded therein, and / or ii) lofted nonwoven comprising an elastically compressible assembly of reinforcing fibers and thermoplastic fibers. Upon closing the chamber, any loft bodies configured as lofted nonwovens are elastically compressed, thereby establishing a first amount of internal pressure. The chamber is then heated to above the thermoplastic softening temperature, thereby bringing the reinforcement bodies and the loft bodies into a thermoplastically formable state, and thereby causing any loft bodies configured as heatable loft bodies to establish a second amount of internal pressure. After a predetermined processing time, the chamber is allowed to cool, thereby solidifying the reinforcement bodies and the loft bodies, thereby producing the structurally reinforced object.

Description

TECHNICAL FIELD

[0001] The present invention relates to a new method of manufacturing a lightweight, structurally reinforced thermoplastic material object, which object comprises at least one reinforcement zone, and to such an object. BACKGROUND

[0002] Composite parts made from fiber-reinforced thermoplastics are being widely used in many technical fields.

[0003] For example, WO 2015 / 117799 A1 discloses a composite part comprising a foam core having first and second skin layers bonded to the foam core on its first and second surfaces, respectively. Similarly, WO 2006 / 133586 discloses a flexurally rigid composite sheet comprising one or two skin layers of 0.5 to 5 mm thickness made from glass fiber-reinforced polypropylene having a glass content of 20 to 60 wt.%, and a core layer of 2 to 40 mm thickness made from glass fiber-reinforced polypropylene having a glass content of 35-80 wt.% and an air void content of 20 to 80 vol.%. As extensively described in WO 2006 / 105682 A1, such porous core sheet can be formed by dry mixing of polypropylene and glass fibers, needle punching of a mixed non-woven fabric and hot pressing. On the other hand, various types of fiber-reinforced thermoplastics are known to be useful as skin layers or other reinforcement zones. In particular, WO 2006 / 111037 A1 discloses a thermoplastically processable sheet-like composite material consisting of (A) at least one non-woven layer comprising 10 to 100 wt.% of thermoplastic fibers and (B) at least one woven fabric of reinforcing fibers, wherein the two layers A and B are needle punched together.

[0004] EP 0 148 763 A2 discloses a method of producing a molded fiber-reinforced plastic article. The method comprises preheating a sheet of thermoplastic material reinforced with glass fibers and introducing the preheated sheet into a mold and subjecting the material to pressure.

[0005] The prior art cited above addresses the general task of optimizing mechanical properties while keeping the weight as small as possible. However, additional challenges arise when a structurally reinforced object is to be manufactured having a more complex shape than a simple planar sheet or plate, e.g. having reinforcement ribs protruding from the basic plane of the object. Notable examples are objects having a T- or H-shaped cross section, and more complex objects having a variable cross section. SUMMARY

[0006] According to the invention, a method of manufacturing a lightweight, structurally reinforced thermoplastic material object, which object comprises at least one reinforcement zone, is provided, the method comprising the steps of:

[0007] a) providing a rigid formable chamber which can be heated, comprising a chamber volume enclosed by a chamber wall and an openable chamber lid;

[0008] b) providing a plurality of thermoplastic bulk bodies and a plurality of thermoplastic reinforcement bodies, the bulk bodies and the reinforcement bodies comprising the same or mutually compatible thermoplastic material, the reinforcement bodies further comprising reinforcing fibers embedded in the thermoplastic material, the bulk bodies being:

[0009] i) thermally bulkable bodies comprising a thermoplastic matrix, the matrix comprising an elastically compressible component of reinforcing fibers embedded therein,

[0010] and / or

[0011] ii) bulk nonwoven bodies comprising an elastically compressible component of reinforcing fibers and thermoplastic fibers;

[0012] and optionally a plurality of rigid filler bodies;

[0013] c) loading the chamber with the bulk bodies, the reinforcement bodies and optionally with the filler bodies at a base temperature below the thermoplastic softening temperature, so as to form an arrangement corresponding to the intended object, wherein the bulk bodies have an initial first volume Vi, the reinforcement bodies have an initial second volume V2, and the filler bodies have an initial third volume V3, and wherein the sum of the initial first, second and third volumes Vo = Vi + V2 + V3 exceeds the chamber volume V by an excess volume Ve, which excess volume Ve is in the range of 0.5 to 0.95 times the initial first volume of any bulk body which is a bulk nonwoven body (ii);

[0014] d) closing the chamber lid, whereby the bulk bodies assume a loaded first volume Vi', the reinforcement bodies assume a loaded second volume V2', and the filler bodies assume a loaded third volume V3' which is substantially equal to the initial third volume V3, and whereby the sum of the loaded first, second and third volumes Vo' = Vi' + V2' + V3' equals the chamber volume V, whereby any bulk body configured as a bulk nonwoven body is elastically compressed, thereby establishing a first amount of internal pressure;

[0015] e) heating the chamber to a processing temperature above the thermoplastic softening temperature, whereby the reinforcement bodies and the bulk bodies enter a thermoplastic formable state, and whereby any bulk body configured as a thermally bulkable body establishes a second amount of internal pressure;

[0016] f) after a predetermined processing time, allowing the chamber to cool, whereby the reinforcement bodies and the bulk bodies solidify, followed by removal of any filler bodies, thereby obtaining the structurally reinforced object.

[0017] According to another aspect of the application, a lightweight structurally reinforced thermoplastic material object is provided, comprising at least one reinforcement zone, and obtainable by the above method, wherein the reinforcement zone has a sheet-like shape, optionally comprising at least one folded edge, and wherein each reinforcement zone is at least partially embedded in a porous thermoplastic material zone. Such lightweight structurally reinforced objects are particularly useful in the automotive and aerospace fields. Examples are reinforced floor and sealing panels. By means of the manufacturing method, such components can be formed in various non-planar shapes. In particular, components can be produced that are formed around a given structural element.

[0018] The present application relies on the use of thermoplastic bulkers, which are to be understood as objects made of thermoplastic material and having a tendency to expand ("bulk") when heated. Two fundamentally different types of bulkers can be used in the present application:

[0019] i) thermally bulkable bulkers comprising a thermoplastic matrix containing an elastically compressible assembly of reinforcing fibers embedded therein. Typically, the reinforcing fibers are brought into a compressed or pre-stressed state by mechanical treatment such as needle punching or water jet treatment, and are "frozen" into the thermoplastic matrix. When heated above the thermoplastic softening temperature, the fibers are no longer bound but tend to expand. This phenomenon is called "bulking".

[0020] ii) bulked nonwovens comprising an elastically compressible assembly of reinforcing fibers and thermoplastic fibers. Such assemblies are provided in a very lightweight state and typically have a volume that is at least 5 times, often 10 times and up to 20 times the volume of a densely packed fiber assembly.

[0021] In principle, both types of thermoplastic bulkers can be used to implement the manufacturing method. In practice, it is preferable to use a single type.

[0022] The thermoplastic bulkers are mainly used to establish or maintain the internal pressure in step e). In addition, they are also used to form relatively lightweight regions in the final object.

[0023] The present application also relies on the use of thermoplastic reinforcements comprising reinforcing fibers embedded in a thermoplastic material. The reinforcements are provided to form relatively high-strength regions in the final product.

[0024] The bulkers and reinforcements preferably comprise the same thermoplastic polymer, although different but in any case compatible thermoplastic polymers with very similar thermoplastic softening temperatures can be used.

[0025] Rigid fillers are optionally provided to define areas within the volume of the chamber that the thermoplastic bulk and the reinforcement will be excluded from. Thus, the fillers help define the shape of the final object. In addition, the fillers provide a rigid structure against which adjacent thermoplastic bodies can be pressed by the action of internal pressure. Since the fillers are optional features, it will be understood that when referred to in the subsequent text, they are referred to only in the case that they are present.

[0026] It will be appreciated that the present application relies on the use of a relatively simple forming chamber. The chamber must be heatable and have rigid chamber walls, including side walls, a bottom wall and a top wall. The chamber should also have closing means that allow a moderate mechanical pressure to be applied during the closing step d). As will be further outlined below, this pressure is required to compress the initially loaded thermoplastic bulk made of a flexible wool mat. However, the forming chamber does not need to work like a high pressure die with walls that are movable at high temperature. This relatively simple construction also provides a high degree of versatility, especially when various types and shapes of rigid fillers are utilized.

[0027] Advantageous embodiments are defined in the dependent claims.

[0028] According to a first embodiment (claim 2), the thermoplastic bulk is configured as a heat-expandable bulk comprising 20 to 80 wt% of a thermoplastic material and 80 to 20 wt% of reinforcing fibers, the reinforcing fibers having an average weight length of 10 to 150 mm and a pore content of 35 to 65 vol%, the pores being uniformly distributed in the matrix. The reinforcing fibers are mechanically entangled with each other and present as filaments to an extent of more than 80%. The mechanical entanglement of the reinforcing fibers is typically produced by needle punching, but other methods such as water jet entanglement can also be used.

[0029] When using this first type of bulk, i.e. a heat-expandable bulk, the loading of the forming chamber is done with an excess volume Ve that is essentially zero. In other words, when performing the above-mentioned step c), the chamber is loaded so that the various bodies placed in it have a total volume that is essentially equal to the volume of the chamber V. Thus, the sum V0 = V1 + V2 + V3, i.e. the sum of the volume V1 of the thermoplastic bulk, the volume V2 of the reinforcement and, if applicable, the volume V3 of the rigid fillers used to load the chamber, is essentially equal to the volume of the chamber V. Thus, there is essentially no pressure in the chamber after closing the chamber lid and before heating.

[0030] As widely described in WO2006 / 105682A1, the thermoplastic bulky material used in the first embodiment can be formed by dry blending thermoplastic fibers and reinforcing fibers, mechanical entanglement of the resulting blended nonwoven fabric, and hot pressing. This type of material is known to be available in various semi-finished products, commercially available as strips or sheets with a preferred width of 300 to 2300 mm, such as SymaLITE from Mitsubishi Chemical Advanced Materials Co., Ltd. Examples of semi-finished products include SEEBERLITE from automotive companies, ACOUSTIMAX from Owens Corning, SUPERLITE from Azdel, and KARAMTEC from Karam Tech. These semi-finished products typically have a thickness of 0.5 to 10 mm before expansion, preferably 1 to 5 mm. Without any confining chamber walls, when heated to temperatures above the softening point of the thermoplastic material, the semi-finished product expands to more than twice its original thickness, preferably three to ten times or more, due to the restoring force of the fibers.

[0031] For this first embodiment, it is advantageous (claim 3) that the initial first volume V1 of the thermoplastic bulk loaded in step c) is 10% to 90% of the sum of the initial volumes V1+V2 of all thermoplastic bodies loaded in step c). A thermoplastic bulk content of less than 10% will not allow sufficient internal pressure to be established in the molding chamber, while a content of more than 90% will excessively limit the amount of reinforcement that provides mechanical stability to the structurally reinforced object to be produced.

[0032] According to the second embodiment (claim 4), the thermoplastic bulk is configured as a bulky nonwoven body, each comprising at least one layer of flexible wool pad containing 10 to 90 wt% thermoplastic material fibers and 0 to 90 wt% reinforcing fibers and having an areal weight of 300 to 3000 g / m². Such wool pads are widely used in the field of manifold technology, particularly for the production of lightweight molded parts with advantageous structural properties. They are typically produced using established carding or air-laid techniques and are essentially formed as sheets.

[0033] When using this second type of bulky material, namely bulky nonwoven material, the loading of the forming chamber is accomplished with a significant excess volume Ve in the range of 0.5 × V1 to 0.95 × V1, preferably in the range of 0.6 × V1 to 0.9 × V1. In other words, up to 95% of the initial volume of the thermoplastic bulky material constitutes an excess volume Ve, which will be compressed and reduced when the chamber is closed. In other words, the initial first volume V1 of the thermoplastic bulky material used for loading into the chamber is 20 times larger, and particularly 10 times larger, than its volume V1' after being loaded into the chamber and the chamber is closed.

[0034] For this second embodiment, it is advantageous (claim 5) that the initial first volume V1 of thermoplastic bulk bodies loaded in step c) is 1 to 100 times the second initial volume V2 of reinforcing bodies loaded in step c).

[0035] If two types (i) and (ii) of bulk bodies are used, the amount of excess volume Ve will be determined by the initial volume of the bulk bodies of the second type, i.e. the bulk nonwoven bodies.

[0036] In principle, the thermoplastic reinforcing bodies can be suitable parts of the essentially known glass fiber mat reinforced thermoplastic sheets (GMT).

[0037] According to a particularly advantageous embodiment (claim 6), the thermoplastic reinforcing bodies comprise:

[0038] A. at least one nonwoven layer comprising 10 to 100 wt.-% of thermoplastic fibers and 0 to 90 wt.-% of reinforcing fibers having an area weight of 200 to 2000 g / m2, 2

[0039] and

[0040] B. at least one woven fabric, non-crimp fabric or unidirectional reinforcing fiber assembly having an area weight of 100 to 1000 g / m2,

[0041] wherein the layers A and B are needled together.

[0042] Such layered thermoplastic reinforcing bodies are extensively described in WO 2006 / 111037 A1. They are commercially available, for example as "Q-Tex" from Mitsubishi Chemical Advanced Materials.

[0043] Depending on the intended purpose of use, at least some of the thermoplastic reinforcing bodies are loaded in a folded state having at least one folded edge (claim 7). In this context, a "folded edge" is to be understood as the region at which two mutually connected non-coplanar regions of an object intersect. In practice, thermoplastic reinforcing bodies having such folded edges are particularly useful for producing objects having a T-shaped or H-shaped cross section.

[0044] According to a further advantageous embodiment (claim 8), in the arrangement formed in step c), the chamber walls and optionally the filler bodies are in contact with the reinforcing bodies. In other words, the chamber is loaded such that the various thermoplastic bulk bodies are not in direct contact with the chamber walls and the filler bodies, but are separated therefrom by the reinforcing bodies.

[0045] If the method of the application is implemented using at least one filler body, there are various advantageous embodiments.

[0046] ​According to one such embodiment (claim 9), each filler body is removable from the arrangement obtained after pulling the cooling chamber. In simple terms, this means that any filler body loaded into the chamber will have at least one portion directly adjacent to the chamber wall, and will have a sufficiently simple shape so as to be removable in step g) without the need to form any slit cut in the material that has been cooled down. A notable example is a filler body having a straight rod shape, which can be pulled out along its longitudinal axis by pulling.

[0047] In another embodiment (claim 10), at least one filler body is configured as an assembly of parts that are releasably connected to each other. In this way, filler bodies having various complex shapes can be constructed. For example, a frame-like structure can be assembled by connecting four rod-shaped parts. While some kind of plug-in or snap-in connection can be used, it is particularly advantageous to employ a threaded connection. In order to function properly under the operating conditions of heating and cooling, the threaded parts need to be properly lubricated.

[0048] In principle, the filler bodies can be made of any sufficiently hard material and capable of withstanding the heating process applied to the chamber. According to an advantageous embodiment (claim 11), the filler bodies are made of metal, preferably stainless steel.

[0049] According to yet another embodiment (claim 12), the filler bodies are actively heatable. In particular, the filler bodies can be heated by induction. As is well known, this implies a suitable material selection, i.e. the filler bodies should be composed of a material having good electrical conductivity.

[0050] As is known in the field of fiber-reinforced thermoplastics, the reinforcing fibers can be chosen from a large number of species. Advantageously (claim 13), the reinforcing fibers are chosen from the group consisting of glass fibers, carbon fibers, aramid fibers, basalt fibers, and natural fibers. Alternatively, the reinforcing fibers can be made of a high-melting thermoplastic, i.e. of a material that does not melt at the processing temperature of heating step e).

[0051] Similarly, the thermoplastic material can be chosen from a variety of known polymers. Advantageously (claim 14), it is chosen from the group consisting of polypropylene (PP), polyetherimide (PEI), polysulfone (PSU), polyethersulfone (PES), polyphenylsulfone (PPSU), polyphenyl dianide (PPA), polyphenylene oxide (PPO), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polyamide (PA), polyaryletherketone (PAEK), polyetherketoneketone (PEKK), and polycarbonate (PC).

[0052] In many advantageous embodiments, especially for the automotive industry, the reinforcing fibers are glass fibers, the thermoplastic material is PP, preferably polypropylene having a melt flow index MFI (230°C, 2.16 kg) of 5 to 500 g / 10 min, preferably 10 to 200 g / 10 min. In further embodiments, carbon fibers are used together with PA. In the aerospace industry, the thermoplastic polymer is advantageously selected from PEI, PEEK, PAEK and PEKK. BRIEF DESCRIPTION OF DRAWINGS

[0053] The above-mentioned and other features and objects of the present application and the manner of achieving them will become more apparent, and the application itself will be better understood by reference to the following description of various embodiments of the application, taken con- jectively with the accompanying drawings, wherein:

[0054] Fig. 1 shows in a schematic perspective view key steps of a manufacturing process according to a first embodiment;

[0055] Fig. 2 shows in a schematic perspective view key steps of a manufacturing process according to a second embodiment;

[0056] Figure 3 A chamber loaded with thermoplastic bulk, thermoplastic reinforcement and rigid filler is shown in cross-section;

[0057] Figure 4 A part of the assembly of frame-like filler bodies in exploded state is shown in perspective view;

[0058] Fig. 5 shows in cross-section examples of lightweight structure-reinforced thermoplastic material objects configured as (a) H-shaped structures, (b) multi-layered tubes; and

[0059] Fig. 6 shows a lightweight structure-reinforced thermoplastic material object of complex shape from a first side (a) and an opposite second side (b) as a photograph representation. DETAILED DESCRIPTION

[0060] It is to be understood that the drawings are not necessarily to scale. In certain instances, the relative dimensions have been deliberately distorted to improve the visibility of the features under discussion. Like or corresponding features throughout the various drawings are denoted by like reference numerals.

[0061] The basic principle of the present application is illustrated in Figs. 1 and 2, which show two embodiments, each exemplified in a particularly simple case (“A-B-A sandwich”). Just to further simplify the explanation, the bulk principle will not be discussed in terms of volume V, but in terms of a single thickness dimension D, which is depicted in horizontal direction.

[0062] For illustration purposes only, the material of the thermoplastic bulk is shown in cold state as a hatched texture, while in hot state above the thermoplastic softening temperature as a full red texture.

[0063] The rigid forming chamber, generally designated 2, is defined by chamber walls, of which the bottom wall 4, the top wall 6, the left wall 8 and the right wall 10 are shown. Two other chamber walls, namely the front wall and the back wall, are not shown. At least one of these walls, for example the top wall 6, is configured as an openable chamber lid. In Figure 1a and 2a the forming chamber is shown in a disassembled state, while in Figure 1b , 1c and 2b, 2c the forming chamber is shown in an assembled and closed state.

[0064] Figures 1a to 1c The first embodiment shown relies on the use of a thermally expandable thermoplastic bulk. As Figure 1a indicated, a plate 12 of thermally expandable material having a thickness D1 is loaded into the chamber 2 sandwiched between a pair of thermoplastic reinforcing bodies 14a, 14b configured as plates having thicknesses D2a and D2b, respectively (only shown in Figure 1b for reasons of space). The total thickness of the thermoplastic reinforcing bodies is thus D2 = D2a + D2b. The situation after this loading step is as shown in Figure 1b Assuming that all loaded bodies have the same planar area A, which also corresponds to the area of each of the inner surfaces of the side walls 8 and 10, the following initial volumes result:

[0065] - initial first volume of the thermoplastic bulk: V1 = A x D1

[0066] - initial second volume of the thermoplastic reinforcing bodies: V2 = A x (D2a + D2b)

[0067] In this example no rigid filler bodies are considered, so the initial third volume V3 is zero.

[0068] The initial total volume V0 is thus as follows:

[0069] V0 = V1 + V2 = Ax (D1 + D2a + D2b)

[0070] In this first embodiment, the dimensions of the various bodies loaded into the chamber exactly match the chamber dimensions, i.e. V0 = V, so the excess volume Ve, defined as Ve = V - V0, is zero. The chamber can thus be closed without compressing any of the loaded bodies. In particular, the loaded first volume V1’ of the thermoplastic bulk equals V1 and the loaded second volume V2’ of the thermoplastic reinforcing bodies equals V2.

[0071] The main situation during the heating step is as shown in Figure 1cThe thermoplastic bulk generates an internal pressure above the thermoplastic softening temperature, which in the simple case shown generates an outward directed force Fl. This causes the flowable thermoplastic material to some extent to rearrange into the residual cavities present in the load object assembly. Depending on the compressible amount of the thermoplastic reinforcement, the internal pressure causes some expansion of the bulk, which will assume a processed first volume VI" slightly larger than VI. This change is accompanied by a corresponding shrinkage of the reinforcement, which will assume a processed second volume V2". This internal pressurization and heating, followed by a subsequent final cooling step, leads to consolidation of the thermoplastic reinforcement and bonding between the thermoplastic bulk and the adjacent faces of the thermoplastic reinforcement.

[0072] Figures 2a to 2c The second embodiment shown relies on the use of a thermoplastic bulk as the bulk nonwoven. As Figure 2a shown, a plate 16 of such elastic material having a thickness Dl is loaded into the chamber 2, sandwiched between a pair of thermoplastic reinforcements 14a, 14b, the reinforcements being configured as plates having thicknesses D2a and D2b, respectively (only shown in Figure 2b for space reasons).

[0073] As in the first example, no rigid filler body is considered, so the initial third volume V3 is zero. Accordingly, again the following initial total volume V0:

[0074] V0 = VI + V2 + V3 = Ax(Dl + D2a + D2b)

[0075] In contrast to this first embodiment, the size of the object loaded into the chamber significantly exceeds the chamber size, i.e. V0 = V + Ve. The excess volume is due to the thickness of the bulk material used for the thermoplastic bulk, and it can be as high as 0.95VI.

[0076] The closing of the chamber will compress the bulk material by up to 20 times, thus requiring a compression of up to about 10 bar. This means that after closing the chamber and before heating, the thermoplastic bulk generates an internal pressure, which in the simple case shown generates an outward directed force F2, see Figure 2b .

[0077] The main situation during the heating step is as Figure 2cThe internal pressure resulting from the compression of the bulk material dominates, although it is generally found to be somewhat lower than in the cold chamber, and thus the outwardly directed force F3 is somewhat smaller than F2. However, as in the first embodiment, the internal pressure causes the flowable thermoplastic material to some extent to re-arrange into the residual cavities present in the assembly of the loaded object. Depending on the compressible amount of the thermoplastic reinforcement, the internal pressure causes the bulk to some extent to expand, which will assume that the first volume V1" of the processed bulk is somewhat larger than V1'. This change is accompanied by a corresponding shrinkage of the reinforcement, which will assume a second volume V2" of the processed bulk. This internal pressurization and subsequent final cooling step results in the consolidation of the thermoplastic reinforcement and the bonding between the adjacent faces of the thermoplastic bulk and the thermoplastic reinforcement.

[0078] In practice, especially when forming objects more complex than the simple A-B-A sandwich structure described above, the choice of the dimensions and shapes of the various bulks loaded into the chamber will require some judicious choices. This is illustrated in Figure 3 where a rigid shaped chamber is shown loaded with, adjacent to each chamber wall, thermoplastic reinforcements 14a, 14b, 14c and 14d, which will form the outer surfaces of the final object to be produced. The chamber further contains two rigid filler bulks 18a and 18b, which define the cavity region of the final object. In this case, each filler bulk has the shape of a square rod. Depending on the dimensions, the rigid filler bulks are thick-walled hollow bodies. Two further reinforcements 14e and 14f, having a substantially C-shaped cross-section, are located around the rigid filler bulks, each having an upper folded edge 20a and a lower folded edge 20b. In addition, the chamber is loaded with substantially plate-like thermoplastic bulks 12a, 12b, 12c and 12d, and substantially C-shaped thermoplastic bulks 12e and 12f, each of which surrounds an adjacent C-shaped reinforcement.

[0079] The rigid filler bulks 18a and 18b can be part of a kit as partially shown in Figure 4 where various rod-shaped filler bulks 18a, 18b and 18c can be assembled with suitable connecting means, such as the illustratively shown bolts 22.

[0080] Figure 5 shows two examples of lightweight structure reinforced objects of thermoplastic material. Figure 5a The H-shaped shaped object of Figure 5 has a core 12 of lightweight thermoplastic material resulting from the initially provided thermoplastic bulk, which is completely surrounded by a skin-like reinforcement zone 14 resulting from the initially provided thermoplastic reinforcement. In contrast, Figure 5b shows a lightweight structure reinforced tube having an outer reinforcement zone 14h and an inner reinforcement zone 14i surrounding an inner zone 12 of lightweight thermoplastic material.

[0081] Finally, Fig. 6 shows another example of a lightweight, structurally reinforced object obtained according to the present application. The object comprises a plate-like main portion, on which two T-shaped reinforcing ribs are integrally formed. In the cross-section visible perpendicular to the plane of the plate, the outer reinforcing zone 14 with a smooth appearance can be seen, only faintly showing the structure due to the reinforcing web structure. Furthermore, the slightly more porous inner zone 12 embedded within the reinforcing zone can be seen.

Claims

1. A method for manufacturing a lightweight, structurally reinforced thermoplastic material object, the object comprising at least one reinforcing region, the method comprising the steps of: a) Provides a heatable rigid forming chamber (2) comprising a chamber volume (V) surrounded by chamber walls (4,6,8,10) and an openable chamber cover (6); b) Provides a plurality of thermoplastic bulks (12, 12a, 12b, 12c, 12d, 12e, 12f; 16) and a plurality of thermoplastic reinforcements (14a, 14b, 14c, 14d, 14e, 14f), wherein the bulks and reinforcements comprise the same or mutually compatible thermoplastic materials, and the reinforcements further comprise reinforcing fibers embedded in the thermoplastic materials. The bulks are: i) A thermoplastic expandable body (12) comprising a thermoplastic matrix containing an elastic compression component with reinforcing fibers embedded therein. and / or ii) bulky nonwovens comprising elastic compressible components of reinforcing fibers and thermoplastic fibers (16); And optionally, multiple rigid infill bodies (18a, 18b, 18c) are provided; c) At a base temperature below the thermoplastic softening temperature, the chamber is loaded with a bulk, a reinforcement, and optionally a filler to form an arrangement corresponding to the intended object, wherein the bulk has an initial first volume V1, the reinforcement has an initial second volume V2, and the filler has an initial third volume V3, and wherein the sum of the initial first, second, and third volumes V0 = V1 + V2 + V3 exceeds the chamber volume V excess volume Ve, which is in the range of 0.5 to 0.95 times the initial first volume of any bulk that is a bulky nonwoven material (ii); d) Close the chamber cover, thereby the bulk material presents a first loaded volume V1', the reinforcement presents a second loaded volume V2', and the filler presents a third loaded volume V3' that is substantially equal to the initial third volume V3, and thereby the sum of the first, second and third loaded volumes V0' = V1' + V2' + V3' equals the chamber volume V, thereby any bulk material configured as a bulky nonwoven is elastically compressed, thereby establishing a first amount of internal pressure; e) Heating the chamber to a processing temperature above the thermoplastic softening temperature, thereby bringing the reinforcement and bulk into a thermoplastic formable state, and thereby establishing a second amount of internal pressure in any bulk configured as a thermoplastic bulk. f) After a predetermined processing time, the chamber is allowed to cool, thereby solidifying the reinforcement and bulk, and then any filler is removed to obtain the structurally reinforced object.

2. The method according to claim 1, wherein, The thermoplastic bulk is a thermoplastic bulk comprising 20 to 80 wt% thermoplastic material and 80 to 20 wt% reinforcing fibers having an average weight length of 10 to 150 mm and a porosity of 35 to 65 vol%, the porosities being uniformly distributed in the matrix, the reinforcing fibers being mechanically entangled with each other and existing as monofilaments to a degree exceeding 80%, and wherein the excess volume Ve is substantially zero.

3. The method according to claim 2, wherein, The initial first volume V1 of the thermoplastic bulk loaded in step c) is 10 to 90% of the sum of the initial volumes V1+V2 of all thermoplastic bodies loaded in step c).

4. The method according to claim 1, wherein, The thermoplastic bulk is a bulky nonwoven body comprising at least one layer of flexible wool pad, the wool pad containing 10 to 90% by weight of thermoplastic material fibers and 0 to 90% by weight of reinforcing fibers and having an area weight of 200 to 3000 g / m2, wherein the excess volume Ve is in the range of 0.5 to 0.

95.

5. The method according to claim 4, wherein, The excess volume Ve is in the range of 0.6 to 0.

9.

6. The method according to claim 4, wherein, The initial first volume V1 of the thermoplastic bulk loaded in step c) is 1 to 100 times the second initial volume V2 of the reinforcement loaded in step c).

7. The method according to claim 4, wherein, The thermoplastic reinforcement includes: A. At least one nonwoven layer comprising 10 to 100% by weight thermoplastic fibers and 0 to 90% by weight an area weight of 200 to 2000 g / m². 2 Reinforcing fibers, and B. At least one woven fabric, non-crimped fabric, or unidirectional reinforcing fiber component with an area weight of 100 to 1000 g / m2. Layer A and layer B are pierced together with needles.

8. The method according to claim 1 or 2, wherein, At least one of the thermoplastic reinforcements is loaded in a folded state with at least one folded edge (20a, 20b).

9. The method according to claim 1 or 2, wherein, In the arrangement formed in step c), the chamber wall and optional filler are in contact with the reinforcement.

10. The method according to claim 1 or 2, wherein, Each filler can be removed by pulling.

11. The method according to claim 1 or 2, wherein, At least one filler is configured as an assembly of releasably interconnected components (18a, 18b, 18c).

12. The method according to claim 1 or 2, wherein, The filler is made of metal.

13. The method according to claim 1 or 2, wherein, The filler is made of stainless steel.

14. The method according to claim 1 or 2, wherein, The filler is actively heatable.

15. The method according to claim 1 or 2, wherein, The reinforcing fibers are selected from glass fibers, carbon fibers, aramid fibers, basalt fibers, natural fibers, and high-melting-point thermoplastic fibers.

16. The method according to claim 1 or 2, wherein, The thermoplastic material is selected from PP, PEI, PES, PSU, PPSU, PPA, PPO, PEEK, PPS, PA, PEAK, PEKK and PC.

17. The method according to claim 1 or 2, wherein, The reinforcing region (14) has a sheet-like shape, optionally includes at least one folded edge, and wherein each reinforcing region is at least partially embedded in a porous thermoplastic material region (12).

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