Method for manufacturing lightweight, structurally reinforced objects from thermoplastic materials

Abstract

A method for manufacturing a lightweight, structurally reinforced object of thermoplastic material including at least one reinforcement zone includes providing a heatable rigid molding chamber (2) having a chamber volume (V). At a base temperature below the thermoplastic softening temperature, the chamber is loaded with a plurality of thermoplastic loftable bodies (12a, 12b, 12c, 12d, 12e, 12f) and a plurality of thermoplastic reinforcements (14a, 14b, 14c, 14d, 14e, 14f). The loftable bodies are: i) a thermally loftable body including a thermoplastic matrix, the thermally loftable body including an elastically compressed mass of reinforcing fibers embedded therein, and / or ii) a lofty nonwoven including an elastically compressible mass of reinforcing fibers and thermoplastic fibers. Upon closing the chamber, any loftable bodies configured as lofty nonwovens are elastically compressed, thereby building up a first amount of internal pressure. The chamber is then heated above the thermoplastic softening temperature, causing the reinforcement and loftable body to become thermoplastically formable, and any loftable body configured as a heat-loftable body to build up a second amount of internal pressure. After a predetermined processing time, the chamber is cooled, causing the reinforcement and loftable body to solidify, resulting in the structurally reinforced object.

Description

Technical Field

[0001] The present invention relates to a novel method for manufacturing a lightweight and structurally reinforced object of a thermoplastic material, comprising at least one reinforcement zone. The present invention also relates to such an object.

Background Art

[0002] Composite parts made from fiber-reinforced thermoplastics are widely used in many technical fields. For example, (Patent Document 1) discloses a composite part including a foam core having a first skin layer and a second skin layer, and the first skin layer and the second skin layer are adhered to the foam core at a first surface and a second surface, respectively. Similarly, (Patent Document 2) discloses a one- or two-layer skin layer with a thickness of 0.5 to 5 mm made from glass fiber-reinforced polypropylene having a glass content of 20 to 60% by weight and a void content of less than 5% by volume, and a core layer with a thickness of 2 to 40 mm made from glass fiber-reinforced polypropylene having a glass content of 35 to 80% by weight and a void content of 20 to 80% by volume, in a bending-rigid composite sheet. Such a porous core sheet can be formed by dry blending of polypropylene fibers and glass fibers, needle punching of the blended non-woven fabric, and hot pressing, as described in detail in (Patent Document 3). On the other hand, various types of fiber-reinforced thermoplastic materials useful as skin layers or other reinforcement zones are known. In particular, (Patent Document 4) discloses a sheet-like composite material that is thermoplastically processable, consisting of (A) at least one non-woven fabric layer containing 10 to 100% by weight of thermoplastic fibers and (B) a fabric of at least one reinforcing fiber, and two layers A and B are needle-punched together.

[0003] (Patent Document 5) discloses a process for manufacturing a fiber-reinforced plastic molded product. This process involves preheating a sheet of a thermoplastic material reinforced with glass fibers, introducing the preheated sheet into a mold, and applying pressure to the material.

Prior Art Documents

[0004] [Patent Document 1] International Publication No. 2015 / 117799 [Patent Document 2] International Publication No. 2006 / 133586 [Patent Document 3] International Publication No. 2006 / 105682 [Patent Document 4] International Publication No. 2006 / 111037 [Patent Document 5] European Patent Application Publication No. 0148763 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The prior art cited above addresses the common challenge of optimizing mechanical properties while keeping weight as low as possible. However, further challenges arise when structurally reinforced objects must be manufactured in shapes more complex than simple planar sheets or boards, such as shapes with reinforcing ribs protruding from the object's base plane. Examples include objects with T-shaped or H-shaped cross-sections, or more complex objects with varying cross-sections. [Means for solving the problem]

[0006] According to the present invention, a method is provided for manufacturing a lightweight, structurally reinforced object of thermoplastic material comprising at least one reinforcing zone, the method comprising: a) A step of providing a heatable rigid molded chamber having a chamber volume V surrounded by chamber walls and an openable chamber lid; b) To provide a plurality of thermoplastic bulky bodies and a plurality of thermoplastic reinforcing bodies, wherein the bulky bodies and reinforcing bodies comprise the same or mutually compatible thermoplastic material, the reinforcing bodies further comprise reinforcing fibers embedded in the thermoplastic material, and the bulky bodies comprise i) A body that can become bulky with heat, comprising a thermoplastic matrix, and / or a body that can become bulky with heat, comprising an elastically compressed aggregate of reinforcing fibers embedded therein, and / or ii) To provide a bulky nonwoven fabric containing an elastically compressible aggregate of reinforcing fibers and thermoplastic fibers, The step of providing a plurality of rigid fillers, optionally; c) A step of loading a bulky body, a reinforcing body and optionally a filler into a chamber at a base temperature below the thermoplastic softening temperature to form an arrangement corresponding to an intended object, wherein the bulky body has an initial first volume V1, the reinforcing body has an initial second volume V2, and the filler has an initial third volume V3, and the sum of the initial first, second, and third volumes V0 = V1 + V2 + V3 exceeds the chamber volume V by an excess volume Ve in the range of 0.5 to 0.95 times the initial first volume of any bulky body which is a bulky nonwoven (ii); d) A step of closing the chamber lid, thereby the bulky body taking on a first loaded volume V1', the reinforcing body taking on a second loaded volume V2', and the packing body taking on a third loaded volume V3' substantially equal to the initial third volume V3, thereby the sum of the first, second and third loaded volumes V0' = V1' + V2' + V3' is equal to the chamber volume V, thereby any bulky body configured as a bulky nonwoven is elastically compressed, resulting in the accumulation of a first amount of internal pressure; e) A step of heating the chamber to a processing temperature exceeding the thermoplastic softening temperature, thereby making the reinforcing body and the bulky body thermoplastically moldable, and further, any bulky body configured as a body that can become bulky with heat, thereby accumulating a second amount of internal pressure; f) After a predetermined processing time, the chamber is cooled so that the reinforcing body and the bulky body solidify and cool, and then any filler is removed to obtain the structurally reinforced object. Includes.

[0007] According to another aspect of the present invention, a lightweight, structurally reinforced object of a thermoplastic material is provided, comprising at least one reinforcing zone and obtainable by the method defined above, wherein the reinforcing zone optionally has a sheet-like shape including at least one folded edge, and each reinforcing zone is at least partially embedded in a zone of porous thermoplastic material. Such lightweight, structurally reinforced objects are particularly useful in the automotive and aerospace fields. Examples include reinforced floor panels and containment plates. The manufacturing method allows such parts to be formed in a variety of non-planar shapes. In particular, it is possible to manufacture parts formed around a given structural element.

[0008] This invention relies on the use of thermoplastic lofting bodies, which are understood to be bodies made of thermoplastic material that tend to expand ("loft") when heated. Two fundamentally different types of lofting bodies can be used in this invention: i) A body that can become bulky with heat, comprising a thermoplastic matrix, and comprising an elastically compressed aggregate of reinforcing fibers embedded therein. Generally, the reinforcing fibers are compressed or prestressed by mechanical treatment such as needlework or waterjet treatment and “frozen” in the thermoplastic matrix. When heated above the thermoplastic softening temperature, the fibers are no longer trapped and tend to expand. This phenomenon is known as “lofting.”

[0009] ii) Bulky nonwovens comprising elastically compressible aggregates of reinforcing fibers and thermoplastic fibers. Such aggregates are provided in a very lightweight state and typically have at least 5 times, typically 10 times, and up to 20 times the volume of a densely packed fiber aggregate.

[0010] In principle, the manufacturing method can be carried out using both types of thermoplastic bulky bodies. In practice, it is preferable to use one type. Thermoplastic bulk bodies are primarily used in step e) to accumulate or maintain internal pressure. Furthermore, such bodies also play a role in forming relatively lightweight regions in the final object.

[0011] The present invention further relies on the use of thermoplastic reinforcements containing reinforcing fibers embedded in a thermoplastic material. Such reinforcements are provided to form regions of relatively high strength in the final product.

[0012] The bulky body and reinforcing members may preferably be made of different but compatible thermoplastic polymers, although they may contain the same thermoplastic polymer and have very similar thermoplastic softening temperatures.

[0013] A rigid filler is optionally provided to define within the chamber volume regions where bulky thermoplastic bodies and reinforcing members are excluded. Therefore, the filler contributes to determining the final shape of the object. Furthermore, the filler provides a rigid structure, and adjacent thermoplastic bodies can be compressed by internal pressure relative to the rigid structure. Since the filler is an optional feature, it should be understood that when it is mentioned in the following text, it is only mentioned if the filler is present.

[0014] As is understood, the present invention relies on the use of a relatively simple molding chamber. This chamber must be heatable and have rigid chamber walls including side walls, bottom walls, and top walls. The chamber must have a closure means that allows for the application of moderate mechanical pressure during closure step d). As will be further outlined below, such pressure is necessary to compress the bulky body of the initially loaded thermoplastic made from a flexible fleece mat. However, the molding chamber does not need to function as a high-pressure mold with movable walls at high temperatures. This relatively simple configuration further offers high versatility, especially when utilizing rigid fillers of various types and shapes.

[0015] Preferred embodiments are defined in the dependent claims. According to the first embodiment (Claim 2), the thermoplastic bulky body is constructed as a body that can become bulky with heat, comprising 20-80% by weight of thermoplastic material, 80-20% by weight of reinforcing fibers having a weight-average length of 10-150 mm, and a void content of 35-65% by volume uniformly distributed in the matrix. The reinforcing fibers are mechanically entangled with each other and exist as individual filaments to a range of more than 80%. The mechanical entanglement of the reinforcing fibers is typically produced by needlework, but other methods such as waterjet entanglement may also be used.

[0016] When using this first type of bulky body, i.e., a body that can become bulky with heat, the loading of the molding chamber is carried out with an excess volume Ve that is substantially zero. In other words, when step c) above is carried out, the chamber is loaded such that the various bodies placed inside have a total volume substantially equal to the chamber volume V. Thus, the sum of V0 = V1 + V2 + V3, i.e., the volume V1 of the thermoplastic bulky body, the volume V2 of the reinforcing body, and the volume V3 of the rigid filler, where applicable, provided to be loaded into the chamber, is substantially equal to the chamber volume V. Therefore, after closing the chamber lid and before heating, there is substantially no pressure inside the chamber.

[0017] In the first embodiment, the body that can be swollen by heat and is used as a thermoplastic swollen body is described in detail in International Publication No. 2006 / 105682 (Patent Document 3). It can be formed by dry blending a thermoplastic fiber and a reinforcing fiber, mechanical entanglement of the obtained blend nonwoven fabric, and hot pressing. This type of material is well known as various semi-finished products commercially available as strips or boards having a width of 300 to 2300 mm. For example, SymaLITE of Mitsubishi Chemical Advanced Materials, SEEBERLITE of Roechling Automotive, ACOUSTIMAX of Owens Corning, SUPERLITE of Azdel, and KARAMTEC of Karam Tech. These semi-finished products generally have a thickness before expansion of 0.5 to 10 mm, preferably 1 to 5 mm. When heated to a temperature exceeding the softening point of the thermoplastic material without restricting the chamber wall, the semi-finished product expands by more than twice the original thickness, preferably more than 3 to 10 times, due to the restoring force of the fibers.

[0018] Regarding this first embodiment, it is advantageous if the initial first volume V1 of the thermoplastic swollen body loaded in step c) is 10 to 90% of the total initial volume V1+V2 of all the thermoplastic bodies loaded in step c) (Claim 3). A composition ratio of less than 10% of the thermoplastic swollen body cannot accumulate sufficient internal pressure in the molding chamber, while a composition ratio exceeding 90% will unduly limit the amount of the reinforcing body that provides the mechanical stability of the structurally reinforced object to be manufactured.

[0019] According to the second embodiment (Claim 4), the thermoplastic swollen body contains 10 to 90% by weight of fibers of the thermoplastic material and 0 to 90% by weight of reinforcing fibers, and 300 to 3,000 g / m2 It is constructed as a bulky nonwoven, each containing at least one layer of flexible fleece mat having a surface weight of . Such fleece mats are widely used in various technical fields and are particularly used to manufacture lightweight shaped parts with advantageous structural properties. Such fleece mats are generally manufactured by established carding or air-laying techniques and are basically formed as sheets.

[0020] When using this second type of bulky body, i.e., bulky nonwoven fabric, the molding chamber is loaded with a considerable 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 body constitutes the excess volume Ve that is compressed and reduced when the chamber is closed. To put it another way, the initial first volume V1 of the thermoplastic bulky body offered for loading into the chamber is up to 20 times, and especially up to 10 times, larger than their volume V1' after being loaded into the chamber and the chamber is closed.

[0021] This second embodiment is advantageous when the initial first volume V1 of the thermoplastic bulky body loaded in step c) is 1 to 100 times the second initial volume V2 of the reinforcing body loaded in step c) (Claim 5).

[0022] When both types (i) and (ii) of bulky bodies are used, the amount of excess volume Ve is determined by the initial volume of those bulky bodies, i.e., the bulky nonwovens, which are the second type.

[0023] In principle, the thermoplastic reinforcement can be a suitable part of a well-known glass-mat-reinforced thermoplastic sheet (GMT).

[0024] According to a particularly advantageous embodiment (claim 6), the thermoplastic reinforcement is A. Containing 10-100% by weight of thermoplastic fibers and 0-90% by weight of reinforcing fibers, with a density of 200-2,000 g / m². 2 A nonwoven fabric layer having a surface weight of, B. 100~1,000g / m 2 A woven fabric, non-crimped fabric, or unidirectional aggregate of reinforcing fibers having a surface weight It consists of layers A and B, which are needle-processed together.

[0025] Such layered thermoplastic reinforcements are described in detail in International Publication No. 2006 / 111037 (Patent Document 4). These are commercially available, for example, from Mitsubishi Chemical Advanced Materials Corporation as "Q-Tex".

[0026] Depending on the intended use, at least a portion of the thermoplastic reinforcement is loaded in a folded state having at least one folded edge (Claim 7). In this regard, “folded edge” is understood as the region of an object where two interconnected, non-coplanar regions intersect. In practice, thermoplastic reinforcements having such folded edges are particularly useful for manufacturing objects having a T-shaped or H-shaped cross-section.

[0027] According to another advantageous embodiment (claim 8), in the arrangement formed in step c), the chamber walls and optional fillers are in contact with the reinforcing members. In other words, the chamber is loaded such that bulky bodies of various thermoplastic materials are separated from the chamber walls and fillers by the reinforcing members rather than being in direct contact with them.

[0028] When the method of the present invention is carried out using at least one filler, various advantageous embodiments exist. According to one such embodiment (claim 9), each filler is removable by pulling it out of the arrangement after the chamber has cooled. In short, this means that any filler loaded into the chamber has at least one portion in direct proximity to the chamber wall and has a shape simple enough to be removable in step g) without the need to cut a gap in the cooled material. A notable example is a straight rod-shaped filler that can be pulled out along its longitudinal axis by pulling.

[0029] In another embodiment (claim 10), at least one filler is configured as an assembly of components that are releasably connected to one another. In this way, fillers with various complex shapes can be constructed. For example, a frame-like structure can be assembled by connecting four rod-shaped components. Some types of plug-in or snap-in connections can be used, but screw connections are particularly advantageous. The screw components require proper lubrication to function properly under heating and cooling operating conditions.

[0030] In principle, the filler can be made of any material that is sufficiently rigid and can withstand the heating process applied to the chamber. According to an advantageous embodiment (claim 11), the filler is made of metal, preferably stainless steel.

[0031] According to yet another embodiment (claim 12), the filler is actively heatable. In particular, the filler may be heatable by induction. As is generally known, this implies appropriate material selection, namely, the filler should be made of a material having good electrical conductivity.

[0032] As is known in the field of fiber-reinforced thermoplastics, reinforcing fibers can be selected from many types. Advantageously (claim 13), the reinforcing fibers are selected from glass fibers, carbon fibers, aramid fibers, basalt fibers, and natural fibers. Alternatively, the reinforcing fibers may be made from high-melting-point thermoplastics, i.e., materials that do not melt at the processing temperature in heating step e).

[0033] Similarly, thermoplastic materials can be selected from a variety of known polymers. Advantageously (claim 14), the thermoplastic material is selected from polypropylene (PP), polyetherimide (PEI), polysulfone (PSU), polyethersulfone (PES), polyphenylenesulfone (PPSU), polyphthalamide (PPA), polyphenylene ether (PPO), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyamide (PA), polyallyl etherketone (PAEK), polyetherketoneketone (PEKK), and polycarbonate (PC).

[0034] In many advantageous embodiments, particularly those for the automotive industry, the reinforcing fibers are glass fibers, and the thermoplastic material is polypropylene (PP), preferably 5-500, and more preferably 10-200 g / 10 min with a melt flow index MFI (230°C, 2.16 kg). 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.

[0035] The above-mentioned and other features and objectives of the present invention, as well as methods for achieving them, will become more apparent by referring to the following descriptions of various embodiments of the present invention, which will be read in conjunction with the accompanying drawings, and the present invention itself will be better understood. [Brief explanation of the drawing]

[0036] [Figure 1a] The main steps of the manufacturing process according to the first embodiment are shown in a schematic perspective view. [Figure 1b]The main steps of the manufacturing process according to the first embodiment are shown in a schematic perspective view. [Figure 1c] The main steps of the manufacturing process according to the first embodiment are shown in a schematic perspective view. [Figure 2a] The main steps of the manufacturing process according to the second embodiment are shown in a schematic perspective view. [Figure 2b] The main steps of the manufacturing process according to the second embodiment are shown in a schematic perspective view. [Figure 2c] The main steps of the manufacturing process according to the second embodiment are shown in a schematic perspective view. [Figure 3] A cross-sectional view shows a chamber loaded with a bulky thermoplastic body, a thermoplastic reinforcement, and a rigid filler. [Figure 4] A perspective view shows a portion of the disassembled frame-like packing assembly. [Figure 5a] A cross-sectional view shows an example of a lightweight, structurally reinforced object made of thermoplastic material, configured as an H-shape. [Figure 5b] A cross-sectional view shows an example of a lightweight, structurally reinforced object made of thermoplastic material, constructed as a multi-layer tube. [Figure 6a] A lightweight, structurally reinforced object with a complex shape made of thermoplastic material is shown as a photographic representation from the first side. [Figure 6b] A lightweight, structurally reinforced object with a complex shape made of thermoplastic material is shown as a photographic representation from a second, opposite side. [Modes for carrying out the invention]

[0037] It should be understood that the figures are not necessarily drawn to a consistent scale. In some cases, relative dimensions are substantially distorted for the sake of easier visualization. Identical or corresponding features in various figures are generally given the same reference number.

[0038] The basic principles of the present invention are shown in Figures 1 and 2, illustrating two embodiments, respectively, particularly for a simple case ("ABA sandwich structure"). For simplicity of explanation, the principle of bulkiness is considered in terms of a single horizontal thickness dimension D, rather than in terms of volume V.

[0039] For illustrative purposes only, the thermoplastic bulky body material is shown with a diagonal texture at low temperatures and with a fully reddish texture at high temperatures exceeding its thermoplastic softening temperature.

[0040] The rigid molding chamber, generally denoted by reference numeral 2, is defined by chamber walls, of which the bottom wall 4, top wall 6, left wall 8, and right wall 10 are shown. Two further chamber walls, namely the front wall and rear wall, are not shown. At least one of these walls, for example, the top wall 6, is configured as an openable chamber lid. The molding chamber is shown disassembled in Figures 1a and 2a, but assembled and closed in Figures 1b, 1c, and 2b, 2c.

[0041] The first embodiment shown in Figures 1a-1c relies on the use of a thermoplastic bulky body that can become bulky with heat. As shown in Figure 1a, a plate 12 of a heat-bulky material having a thickness D1 is loaded into the chamber 2, sandwiched between pairs of thermoplastic reinforcements 14a, 14b, each consisting of plates having thicknesses D2a and D2b (shown only in Figure 1b for space reasons). Thus, the total thickness of the thermoplastic reinforcements is D2 = D2a + D2b. The state after this loading step is shown in Figure 1b. Assuming that all loads have the same planar area A (which also corresponds to the area of ​​each inner surface of sidewalls 8 and 10), the following initial volume is obtained.

[0042] - Initial first volume of a thermoplastic bulky body: V1 = A × D1 - Initial second volume of thermoplastic reinforcement: V2 = A × (D2a + D2b) In this example, since a rigid filler is not considered, the initial third volume V3 is zero.

[0043] Therefore, it has the following initial total volume V0. V0 = V1 + V2 = A × (D1 + D2a + D2b) In this first embodiment, the sizes of the various bodies loaded into the chamber are equal to the chamber size, i.e., V0 = V, and accordingly, the excess volume Ve, defined as Ve = V - V0, is zero. As a result, the chamber can be closed without compressing the loaded bodies in any way. In particular, the first volume V1' loaded with thermoplastic bulky bodies is equal to V1, and the second volume V2' loaded with thermoplastic reinforcement V2' is equal to V2.

[0044] Next, Figure 1c shows the situation during the heating step. Above the thermoplastic softening temperature, the bulky thermoplastic body generates internal pressure, which in the simple case shown in the figure produces an outward force F1. This causes the fluid thermoplastic material to be redistributed into residual cavities present in the assembly of the filler. Depending on the compressibility of the thermoplastic reinforcement, the bulky body expands to some extent due to the internal pressure, taking on a treated first volume V1'' that is somewhat larger than V1'. This change is accompanied by the contraction of the reinforcement, which takes on a treated second volume V2''. This internally pressurized heating and the subsequent final cooling step compact the thermoplastic reinforcement, joining the adjacent surfaces of the bulky thermoplastic body and the thermoplastic reinforcement.

[0045] The second embodiment shown in Figures 2a-2c relies on the use of a bulky thermoplastic body, which is a bulky nonwoven material. As shown in Figure 2a, a plate 16 of such bulky material having a thickness D1 is loaded into a chamber 2, sandwiched between pairs of thermoplastic reinforcements 14a, 14b, which are plates having thicknesses D2a and D2b (shown only in Figure 2b for space reasons).

[0046] Similar to the first embodiment, since no rigid filler is considered, the initial third volume V3 is zero. Therefore, again, the initial total volume V0 is as follows: V0 = V1 + V2 + V3 = A × (D1 + D2a + D2b) In contrast to this first embodiment, the size of the body loaded into the chamber substantially 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 body and can sometimes reach a high value of 0.95V1.

[0047] When the chamber is closed, the bulky material is compressed to 1 / 20th of its original volume, thus requiring a maximum compression of approximately 1,000 kPa (10 bar). That is, after closing the chamber and before heating, the thermoplastic bulky body generates internal pressure, which in the simple case shown in the figure produces an outward force F2. See Figure 2b.

[0048] Next, Figure 2c shows the conditions during the heating step. It can be seen that the internal pressure due to the compression of the bulk material is dominant, but is generally somewhat lower than in the low-temperature chamber, and the outward force F3 is somewhat smaller than F2. Nevertheless, as in the first embodiment, the internal pressure results in some rearrangement of the fluid thermoplastic material into the residual cavity present in the assembly of the load. Depending on the amount of compressibility of the thermoplastic reinforcement, the internal pressure results in some expansion of the bulky body, which takes on a processed first volume V1'' somewhat larger than V1'. This change is accompanied by contraction of the reinforcement, which takes on a processed second volume V2''. This internally pressurized heating, followed by the final cooling step, compacts the thermoplastic reinforcement and joins the adjacent surfaces of the thermoplastic bulky body and the thermoplastic reinforcement.

[0049] In practice, especially when molding objects with structures more complex than the simple ABA-type sandwich structure described above, a certain degree of care is required in selecting the size and shape of the various fillers to be loaded into the chamber. This is shown in Figure 3, which indicates that the rigid molding chamber is loaded as follows: adjacent to each chamber wall are thermoplastic reinforcing bodies 14a, 14b, 14c, and 14d, which form the outer surface of the final object to be manufactured. The chamber further includes two rigid fillers 18a and 18b, which define the cavity area of ​​the final object. In this case, each filler has the shape of a rectangular bar. Depending on the size, the rigid fillers are thick-walled hollow bodies. Two further reinforcing bodies 14e and 14f, having a roughly C-shaped cross-section with an upper bent edge 20a and a lower bent edge 20b, respectively, are arranged around the rigid fillers. Furthermore, the chamber is loaded with roughly plate-shaped thermoplastic bulky bodies 12a, 12b, 12c, and 12d, and roughly C-shaped thermoplastic bulky bodies 12e and 12f that surround adjacent C-shaped reinforcing bodies, respectively.

[0050] The rigid fillers 18a and 18b may be part of a kit, as partially shown in Figure 4. Various rod-shaped fillers 18a, 18b, and 18c can be assembled with suitable connecting means, such as the threaded bolts 22 shown schematically.

[0051] Two examples of lightweight, structurally reinforced objects made of thermoplastic material are shown in Figure 5. The H-shaped object in Figure 5a has a lightweight thermoplastic core 12 derived from a bulky thermoplastic body initially provided, which is entirely surrounded by a skin-like reinforcement zone 14 derived from a thermoplastic reinforcement initially provided. In contrast, Figure 5b shows a lightweight, structurally reinforced tube having an outer reinforcement zone 14h and an inner reinforcement zone 14i surrounding the inner zone 12 of the lightweight thermoplastic material.

[0052] Finally, Figure 6 shows a further example of a lightweight, structurally reinforced object obtained by the present invention. This object includes a plate-like main portion on which two T-shaped reinforcing ribs are integrally formed. The structure visible in a cross-sectional cut perpendicular to the plate surface reveals an external reinforcing zone 14 with a smooth appearance that slightly reveals the structure resulting from the reinforcing web structure. Furthermore, a slightly porous internal zone 12 can be seen embedded within the reinforcing zone.

Claims

1. A method for manufacturing a lightweight, structurally reinforced object made of thermoplastic material, comprising at least one reinforcement zone, a) Providing a heatable rigid molded chamber (2) including a chamber volume (V) surrounded by chamber walls (4, 6, 8, 10) and an openable chamber lid (6); b) Providing a plurality of thermoplastic bulky bodies (12, 12a, 12b, 12c, 12d, 12e, 12f) and a plurality of thermoplastic reinforcements (14a, 14b, 14c, 14d, 14e, 14f, 16), wherein the bulky bodies and the reinforcements comprise the same or mutually compatible thermoplastic material, the reinforcements further comprise reinforcing fibers embedded in the thermoplastic material, and the bulky bodies i) a body (12) that can become bulky with heat, comprising a thermoplastic matrix and an elastically compressed aggregate of reinforcing fibers embedded therein, and / or ii) A bulky nonwoven fabric (16) comprising an elastically compressible aggregate of reinforcing fibers and thermoplastic fibers; b1) Providing a plurality of rigid fillers (18a, 18b, 18c); c) A step of loading a bulky body, a reinforcing body and a filler into the chamber at a base temperature below the thermoplastic softening temperature to form an arrangement corresponding to the intended object, wherein the bulky body has an initial first volume V1, the reinforcing body has an initial second volume V2, and the filler has an initial third volume V3, and the sum of the initial first, second and third volumes V0 = V1 + V2 + V3 exceeds the chamber volume V by an excess volume Ve in the range of 0.5 to 0.95 times the initial first volume of any bulky body which is a bulky nonwoven (ii), and the excess volume Ve is zero if there is no bulky body which is a bulky nonwoven (ii); d) A step of closing the chamber lid, thereby the bulky body taking on a first loaded volume V1', the reinforcing body taking on a second loaded volume V2', and the packing body taking on a third loaded volume V3' substantially equal to the initial third volume V3, thereby the sum of the first, second and third loaded volumes V0' = V1' + V2' + V3' being equal to the chamber volume V, and furthermore, any bulky body configured as a bulky nonwoven is elastically compressed, thereby accumulating a first amount of internal pressure; e) A step of heating the chamber to a processing temperature exceeding the thermoplastic softening temperature, thereby making the reinforcing body and the bulky body thermoplastically moldable, and further, any bulky body configured as a body that can become bulky with heat, accumulating a second amount of internal pressure; f) A method comprising the steps of cooling the chamber after a predetermined processing time so that the reinforcing body and the bulky body solidify and cool, and then removing any filler to obtain the structurally reinforced object.

2. The method according to claim 1, wherein the thermoplastic bulky body comprises only a body that can become bulky with heat, comprising 20 to 80% by weight of the thermoplastic material, 80 to 20% by weight of reinforcing fibers having a weight-average length of 10 to 150 mm, and a void content of 35 to 65% by volume uniformly distributed in the matrix, wherein the reinforcing fibers are mechanically intertwined with each other and exist as individual filaments in a range exceeding 80%, and the excess volume Ve is zero.

3. The method according to claim 2, wherein the initial first volume V1 of the bulky thermoplastic body 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 bulky thermoplastic body comprises 10 to 90% by weight of the thermoplastic material fibers and 0 to 90% by weight of reinforcing fibers, and has a density of 200 to 3,000 g / m². ２ The method according to claim 1, comprising only a bulky nonwoven fabric having a surface weight of 0.5 to 0.95, wherein the excess volume Ve is in the range of 0.5 to 0.

95.

5. The method according to claim 4, wherein the initial first volume V1 of the thermoplastic bulky body loaded in step c) is 1 to 100 times the initial second volume V2 of the reinforcing body loaded in step c).

6. The thermoplastic reinforcement is A. Containing 10-100% by weight of thermoplastic fibers and 0-90% by weight of reinforcing fibers, with a density of 200-2,000 g / m². ２ At least one nonwoven fabric layer having a surface weight, B. 100~1,000g / m ２ The method according to any one of claims 1 to 5, comprising at least one woven fabric, non-crimped fabric or unidirectional aggregate of reinforcing fibers having a surface weight, wherein layers A and B are needle-processed together.

7. The method according to any one of claims 1 to 6, wherein at least one of the thermoplastic reinforcing members is loaded in a folded state having at least one folded edge (20a, 20b).

8. The method according to any one of claims 1 to 7, wherein in the arrangement formed in step c), the chamber wall and the filling body are in contact with the reinforcing body.

9. The method according to any one of claims 1 to 8, wherein each filler can be removed by pulling.

10. The method according to any one of claims 1 to 8, wherein at least one filler is configured as an assembly of components (18a, 18b, 18c) that are releasably connected to one another.

11. The method according to any one of claims 1 to 10, wherein the filler is made of metal.

12. The method according to any one of claims 1 to 11, wherein the filling is actively heatable.

13. The method according to any one of claims 1 to 12, wherein the reinforcing fiber is selected from glass fiber, carbon fiber, aramid fiber, basalt fiber, natural fiber, and high melting point thermoplastic fiber.

14. The method according to any one of claims 1 to 13, wherein the thermoplastic material is selected from PP, PEI, PES, PSU, PPSU, PPA, PPO, PEEK, PPS, PA, PAEK, PEKK, and PC.

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