Composite shell

Abstract

This invention relates to a composite shell, for example, part of a patient bed commonly found in the technical equipment of large medical devices, and / or as part of a flexurally resistant composite component, for example, in seats, beds, storage units, and / or vehicle interiors. With this invention, for the first time, sustainability in the manufacture of large medical devices, including composite shells for patient bed slabs, is technically achieved. Therefore, it is possible (by, for example, in patient bed slabs, car seats, and other flexurally resistant composite components, to selectively use nonwoven fabrics instead of expensive continuous fibers in the composite shell) to construct components that are mechanically nearly as good, using recycled and / or waste fiber reinforced nonwoven fabrics instead of newly produced continuous fibers.

Description

Technical Field

[0001] This invention relates to a composite shell, for example, as part of a patient bed, which is commonly found in the technical equipment of large medical devices, and / or as part of a flexurally resistant composite component, for example, in seats, beds, storage devices, and / or vehicle interiors.

[0002] Patient beds provide ergonomic, comfortable, and functional solutions for supporting and / or treating patients in a medical setting. Patient beds exist that incorporate this composite shell as a flexural composite component in the form of a bed board.

[0003] For example, patient beds, used to accommodate and / or position patients and their movement through the scanning plane, are used in large medical devices such as computed tomography (CT), molecular imaging (MI), X-ray equipment, and magnetic resonance imaging (MRI) and angiography (AT) environments. Furthermore, patient beds are also used in radiotherapy irradiation using X-ray or particle radiation, for corresponding irradiation planning, or in medical interventions via imaging.

[0004] The design of patient beds for medical applications always takes into account both the mechanical stability and / or stiffness of the composite shell, and its permeability and / or imaging and / or X-ray absorption characteristics, which may affect image quality and the X-ray dose applied to the patient. Therefore, the composite shell for patient beds is preferably designed to be X-ray transparent.

[0005] On the one hand, the patient bed must be as light and thin as possible to minimize the beam load and / or dose rate applied to the patient. On the other hand, mechanical specifications regarding strength and stiffness must be met because, for example, in applications, patients with high weights (e.g., over 125 kg) also move across the scanning plane of the device in a high extension of the bed board (e.g., within a 1.5 m lever arm). Therefore, the composite shell of the patient bed must not only not break, but also not exceed a certain deflection tolerance in the area of ​​the scanning plane in order to hold the patient at the isocenter. Excessive deflection can lead to impaired image quality and thus compromise the diagnostic accuracy.

[0006] High mechanical stability is often achieved by increasing the amount of material used, which, for example, reduces X-ray transparency. Therefore, the described design criteria—bending strength on the one hand and brightness or transparency relative to the radiation being applied on the other—are often contradictory. Background Technology

[0007] Patient beds according to the prior art have a composite shell typically made of fiber-plastic composites and / or composites, which, for example, have a rigid foam core. Fiber composites are multiphase or mixed materials that typically comprise two main components: an embedded matrix and reinforcing fibers. Here, the reinforcing fibers and the embedded matrix perform very specific tasks. Through the interaction of the two components, the fiber composite acquires better properties than each of the two individual involved components. However, this also results in the two involved materials having very different properties.

[0008] For example, carbon fiber-based continuous fiber-reinforced plastics (CFK) are used. Thermosetting plastics and / or thermoplastic plastics, as well as any mixtures and fusions made therefrom, form the embedded matrix. For example, a composite shell for a patient bed comprises a composite material that, in cross-section, shows a hybrid structure made of CFK layers with different fiber orientations, wherein, in particular, the primary bending load is oriented along the member. Here, for example, a layered structure of the composite shell is achieved, and 100 or more monolayers with different partial opposite fiber orientations may exist.

[0009] A so-called sandwich structure exists in composite shells, in which two flexurally resistant composite layers surround a core made of rigid foam and / or other core materials. These sandwich solutions can typically be established via a process of extruding the wet dressing layer through hydraulic extrusion and / or an autoclave with a vacuum bag structure. Known sandwich structures for patient beds are described, for example, in DE102022205106.

[0010] In addition, there are monolithic structures in which the components / patient beds consist only of fiber linings in cross-section. These are produced, for example, from dried reinforcing fibers via liquid resin injection.

[0011] To date, there is no scheme to introduce the material of composite shells (regardless of structure, whether monolithic or sandwich structure) into the material cycle of patient beds. Therefore, a technological solution is needed in which the material technology of the composite shell, particularly for patient beds, is at least partially provided by material recycling. Summary of the Invention

[0012] The objective of this invention is to provide a sustainable material technology for composite shells (e.g., as part of a patient bed) based on recycled reinforcing fibers and / or waste fibers, with technical characteristics similar to those of composite shells made from entirely new fibers.

[0013] This task is solved by the subject matter of the present invention, which is disclosed, for example, in the specification, claims and drawings.

[0014] Accordingly, the subject of the present invention is a sandwich-structured composite shell comprising two outer composite layers as outer layers and a core in the middle, wherein a nonwoven-reinforced composite material is contained in the core and / or in the two surrounding outer composite layers, the composite material comprising fibers from recycled materials and / or production waste in the nonwoven fabric.

[0015] Design scheme of the present invention

[0016] According to one implementation, the composite shell is part of the bed board of the patient bed.

[0017] According to another embodiment, the core comprises a nonwoven reinforced composite material.

[0018] According to one embodiment, the core of the composite shell comprises a composite material (in bulk form) having nonwoven reinforcement.

[0019] According to another embodiment, the composite layer package includes up to 300, particularly up to 150, single layers.

[0020] According to one implementation, the composite shell is constructed symmetrically around the core, such that the two outer layers in the composite stack form have the same number of single layers.

[0021] According to one embodiment, the composite shell is constructed symmetrically around the core, such that the two composite stacks have the same and / or reflective, i.e., axisymmetric, monolayer arrangement in terms of the orientation of the monolayer with continuous fiber reinforcement.

[0022] According to one embodiment, at least one monolayer of the composite layer package comprises a fiber reinforcement having oriented continuous fibers.

[0023] According to one embodiment, at least one single layer of the composite layer package includes a nonwoven reinforcement.

[0024] According to one embodiment, a layer structure exists in at least one composite stack, wherein the fiber orientations of two consecutive monolayers having fiber reinforcements made of oriented continuous fibers are rotated 90 degrees relative to each other.

[0025] According to one embodiment, a sandwich structure exists in the composite shell, which has the following single-layer sequence:

[0026] - Two or more monolayers having fiber reinforcement and at least partially disoriented continuous fibers.

[0027] - A core made of bulk composite material with nonwoven reinforcement.

[0028] - Two or more monolayers having fiber reinforcement and at least partially disoriented continuous fibers.

[0029] According to another embodiment, a sandwich structure exists in the composite shell, which has the following single-layer sequence:

[0030] - Two or more monolayers having fiber reinforcement, wherein at least two adjacent monolayers have continuous fibers oriented by rotation of 90 degrees.

[0031] - Multiple single layers within the core, which have nonwoven reinforcement.

[0032] - Two or more monolayers having fiber reinforcement, wherein at least two adjacent monolayers have continuous fibers oriented by rotation of 90 degrees.

[0033] The term "sandwich structure" currently refers to a structure that represents a multilayered material solution, wherein there are two outer regions and an intermediate region, with the intermediate region also referred to as the core. In the boundary case, if the core and the surrounding composite layers are constructed identically, i.e., have the same multilayered material solution, then known monolithic structures of composite shells can also fall under the term "sandwich structure."

[0034] According to existing technology, the core of a traditional sandwich structure mainly consists of a compact and / or foamed plastic solution with or without a fiber solution.

[0035] Instead, the current recommendation is that the core is made of a single layer with nonwoven reinforcement (as a bulk composite core) and / or multiple single layers with nonwoven reinforcement, wherein the core, as already mentioned, does not necessarily differ from the surrounding outer layers in the composite and laminate structure.

[0036] The thickness or wall thickness of the composite shell is in the range of 0.5 mm to 100 mm, preferably 5 mm to 50 mm, and particularly preferably in the range of 7 mm to 35 mm.

[0037] Here, the thickness of the core is in the range of 0.1 mm to 50 mm, preferably 0.5 mm to 30 mm, and particularly preferably 0.7 mm to 20 mm.

[0038] Depending on the internal structure in the region of core thickness, the thickness of the outer layer in the form of a composite stack is equal to or, for example, less than the core thickness, and is correspondingly in the range of 0.1 mm to 30 mm, preferably 0.5 mm to 15 mm, and particularly preferably in the range of 1 mm to 10 mm.

[0039] The typical thickness of a single layer is approximately in the range of 0.1 mm to 1 mm.

[0040] The thickness of the nonwoven-reinforced bulk composite core as a molded body ranges from 0.1 mm to 50 mm.

[0041] The composite stack forms the outer layer and comprises a series of monolayers made of composite materials. "Composite material" refers to a material composed of reinforcing fibers within a plastic matrix. The fiber reinforcement forms the "robust" portion of the fiber-reinforced plastic and exists, for example, in the form of fibers, fiber bundles, yarn bundles, fiber-free fabrics, classic woven structures, and / or as nonwoven fabrics.

[0042] Nonwoven fabrics include not only planar nonwoven fabrics existing in the form of layers, stacks, films and / or single layers, such as so-called sheets, but also nonwoven fabrics forming three-dimensional and irregular fiber composites that appear as clouds and are so-called bulk materials before being treated with resin to form composite materials.

[0043] Currently, "nonwoven reinforcement" refers to composite materials that include recycled fibers and / or waste fibers. Nonwoven reinforced composite materials are part of the plastics recycling process.

[0044] Accordingly, reinforcing fibers can exist as continuous fibers, as fiber bundles, as individual fibers of a specific length, as fiber composites, as fiber-free fabrics, as fiber-woven fabrics, and / or as nonwoven fabrics. In the primary manufacturing of expensive textiles using costly continuous fibers, such as carbon fibers, e.g., unidirectional “UD” carbon fibers and / or high-modulus carbon fibers and high-tenacity (“HighTenacity”) carbon fibers, so-called “scrap” generates waste that can be used in the form of nonwoven fabrics. These are currently also referred to as “waste fibers.”

[0045] Unlike simple fibers, woven fabrics, defined fiber composites, and / or defined fiber bundles, nonwoven fabrics are disordered, statistically defined “nonwoven” arrangements of fibers and / or fiber fragments. For example, optical evaluation provides evidence for the use of nonwoven fiber solutions in fiber-reinforced plastics because nonwoven fabrics possess different optical properties than woven, non-bent fiber fabrics, and / or fiber composites. While defined arrangements of fibers are typically characterized by classical woven structures, nonwoven structures are arbitrary and disordered. In English, “nonwoven” refers to nonwoven fabric, meaning that all types of fiber arrangements other than those produced in a regular pattern, such as in weaving, can be understood as the term “nonwoven fabric.” Nonwoven fabrics are flexible, woven surface-formed or three-dimensional bulk materials.

[0046] Typical fiber lengths in nonwoven fabrics range from a lower limit of 2mm to 7mm to an upper limit of 300mm to 400mm. For example, they are in the range of 8mm to 170mm, and especially in the range of 10mm to 100mm.

[0047] All common inorganic and / or organic reinforcing fibers, preferably recycled and / or waste fibers, and any combination and mixture thereof are considered fibers for use in nonwoven fabrics. This includes, for example, all types of carbon fibers, glass fibers, organic fibers such as aramid fibers, PET (polyethylene phthalate) fibers, PP (polypropylene) fibers, cellulose, ceramic fibers, such as metal oxides like corundum fibers (Al₂O₃), and silicon carbide fibers. The aforementioned fibers can be used alone or in mixtures and in any combination in nonwoven fabrics.

[0048] For example, different fiber types and / or fiber qualities can be used in bundles in yarn or as pultrudes in general for constructing nonwovens. By combining different reinforcing fibers, all types of physical and chemical properties of the resulting nonwoven fiber-reinforced composites can be specifically achieved and influenced.

[0049] As described above, the polymerization matrix may include, for example, thermosetting resins based on one of these compounds, such as glycidyl ether, phenolic varnish, epoxy resin, vinyl ester resin, polyurethane, polyester, silicone, polyethylene, ultra-high molecular weight polyethylene, and any mixtures, blends, or copolymers of the above compounds. Furthermore, various thermoplastics may also be used, such as polyurethane, polyethylene terephthalate, polypropylene, and any mixtures, blends, or copolymers of the above compounds.

[0050] Nonwoven fabrics can be used to create planar composites or bulk materials by layering single layers. For example, sheet molding compound "SMC" or bulk molding compound "BMC" can also be manufactured with nonwoven reinforcement using recycled fibers, and / or are currently used to construct composite shells.

[0051] Different fibers, fiber residues, and recycled fibers are used to manufacture nonwoven fabrics. Recycled fibers are known, meaning fibers recovered from used materials and / or products. These fibers exist in woven, knitted, weft-knitted, and / or warp-knitted fabrics. Additionally, there are waste fibers, which, although virgin, originate from production waste such as scraps and industrial waste.

[0052] To manufacture composite materials, fiber reinforcements are, for example, submitted and impregnated with liquid resin, saturated, and / or submerged in a pool containing resin. The resulting composite is then cured by temperature, drying, etc., thereby forming fiber-reinforced plastics, composite materials. The polymerization of the initial liquid matrix material is achieved by using a hardener as an additive and / or by free radical polymerization, or by using a starter or initiator as a homopolymer in the absence of a hardener.

[0053] To form a composite stack, multiple thin monolayers made of composite materials are stacked on top of each other. The resulting stack is packaged, for example, in a film bag, vacuumed under pressure, placed in an autoclave, and thermoformed at a pressure of about 10 bar and a high temperature in the autoclave. Attached Figure Description

[0054] Figure 1 An example design of a composite shell according to an exemplary embodiment of the present invention is shown.

[0055] Figure 2 An exemplary layered structure of the composite shell is shown.

[0056] Figure 3 The exemplary embodiments of the present invention illustrate the effect of recycling modifications on the bending stiffness of the composite shell. Detailed Implementation

[0057] exist Figure 1 Composite shell 1 can be seen in the image. Composite shell 1 shows a shell shape that is common in, for example, bed boards for patient beds. Figure 1 The details of the composite shell 1 are also magnified, revealing the sandwich structure. Two outer layers of the composite stack 2, in the form of surrounding the core 3, are visible. Each of the composite stacks 2 comprises a series of monolayers, which are either fiber-reinforced or nonwoven-reinforced. The core 3 comprises, for example, a nonwoven-reinforced composite material (in the form of a monolayer and / or in the form of bulk material).

[0058] Currently, "fiber reinforcement" refers to the presence of fiber reinforcement (such as continuous fibers) in composite materials, while "non-woven reinforcement" refers to the presence of non-woven fabric (with a corresponding proportion of recycled fibers) as a rigid component in composite materials.

[0059] Figure 2 The layer structure of composite shell 2 is shown in tabular form. The table shows the oriented fiber reinforcement with reinforcing fibers, so that for a single layer, the data on the orientation [angle specification º] of the continuous fibers can be read in the leftmost column, the data on the weight [g / m2] of the single layer can be read in the middle column, and the data on the thickness [mm] of the layer can be read in the rightmost column. The orientation of the single layer with fiber reinforcement is therefore arranged in the longitudinal direction at 0º, in the transverse direction at 90º, and in a certain direction at + / -45º, so that it produces substantially the same properties in all directions, and the composite shell thus withstands longitudinal, transverse and / or torsional loads equally well.

[0060] In the test, the six intermediate monolayers from the composite shell were now replaced by monolayers reinforced with nonwoven fabrics containing cyclically guided fiber material and / or scrap and / or waste fiber material, and the bending stiffness of the two composite shells was compared with each other.

[0061] Figure 3 The results of the test described above are shown graphically. The load is plotted in [kg] on the horizontal axis, and the deflection in [mm] on the vertical axis. The following figure, showing the measurement points with squares, illustrates the conventional method as described above. Figure 2 The table shows a composite shell constructed with only a single layer consisting of oriented continuous monofiber reinforcement, and slightly above, i.e. less resistant to bending, a modified composite shell using a nonwoven fabric-reinforced single layer is shown (according to an exemplary embodiment of the invention), the measurements of which are shown using graphical dots of circular records.

[0062] It is clear that when the expensive continuous fibers in the fiber reinforcement are replaced by nonwoven reinforcement composed of recycled and / or waste fibers, the component stiffness of the composite shell is reduced only slightly.

[0063] This confirms that sustainability is possible in the manufacture of composite shells. Because single-layer nonwoven reinforcement (according to its installation in a composite stack from a single layer to a sandwich structure) provides test results in flexural stiffness that are almost as good as those of pure fiber reinforcement. Therefore, the availability of recycling channels for fibers and fiber waste is technically feasible in the manufacture of composite shells.

[0064] In particular, it offers advantages in terms of resource efficiency, the use of recycled materials, and its ecological and economic footprint. In this case, recycled fiber can be considered as having a zero carbon dioxide material footprint. Therefore, it enables and promotes sustainable improvements in high-energy feedstocks in multiple aspects.

[0065] In applications, for example, at the center of the cross-section in the region of neutral fibers, under bending loads, the aforementioned components may be partially or completely replaced by nonwoven fabrics based on "recycled carbon fiber" (rCF) or other materials.

[0066] Another advantage of the aforementioned alternative for + / -45º continuous fiber layers is the cost advantage when rCF material is used as a nonwoven fabric, as the expensive manufacturing of CF fibers is eliminated.

[0067] This invention achieves, for the first time, technological sustainability in the manufacture of large medical devices, including composite shells for patient bed slabs. Therefore, it is possible (for example, in patient bed slabs, car seats, and other flexurally resistant composite components, to selectively use nonwoven fabrics instead of expensive continuous fibers in the composite shell) to construct mechanically nearly identical components using recycled and / or waste nonwoven fabrics, rather than using newly produced continuous fibers.

Claims

1. A sandwich-structured composite shell comprising two outer composite layers as outer layers and a core in the middle, wherein, The core and / or the two surrounding outer composite layers contain a nonwoven-reinforced composite material, the composite material comprising fibers from recycled materials and / or production waste in the nonwoven fabric.

2. The composite shell according to claim 1, wherein, The core has recycled fibers in a nonwoven reinforcement.

3. The composite shell according to claim 1, wherein, The composite shell is part of a patient bed used for diagnostic and / or therapeutic medical devices.

4. The composite shell according to claim 1 or 2, wherein, The core of the composite shell comprises a composite material in the form of a bulk material having nonwoven reinforcement.

5. The composite shell according to any one of the preceding claims, wherein, Up to 300 single layers can be achieved in a composite layer package.

6. The composite shell according to any one of the preceding claims, wherein, The composite shell is constructed symmetrically around the core.

7. The composite shell according to any one of the preceding claims, wherein, The composite shell has at least one monolayer in the composite layer package, the monolayer having fiber reinforcement made of oriented continuous fibers.

8. The composite shell according to any one of the preceding claims, the composite shell having at least one monolayer in the composite layer package, the monolayer having a fiber reinforcement made of a nonwoven reinforcement.

9. The composite shell according to any one of the preceding claims, wherein, At least in the composite stack, there exists a layer structure in which two continuous monolayers of fiber reinforcement made of oriented continuous fibers are rotated 90 degrees relative to each other.

10. The composite shell according to any one of the preceding claims, wherein, The wall thickness of the composite shell is in the range of 0.1 mm to 100 mm.

11. The composite shell according to any one of the preceding claims, wherein, A sandwich structure exists with the following single-layer sequence: - Two or more monolayers, each monolayer having fiber reinforcement and at least partially disoriented continuous fibers. - A core made of bulk composite material, the core having nonwoven reinforcement. - Two or more monolayers, wherein the monolayers have fiber reinforcement and at least partially disoriented continuous fibers.

12. The composite shell according to any one of the preceding claims, wherein, A sandwich structure exists with the following single-layer sequence: - Two or more monolayers, each monolayer having fiber reinforcement, wherein at least two adjacent monolayers have continuous fibers oriented by a 90-degree rotation. - Multiple monolayers within the core, each monolayer having a nonwoven fabric reinforcement. - Two or more monolayers, wherein the monolayers have fiber reinforcement, wherein at least two adjacent monolayers have continuous fibers oriented by rotation of 90 degrees.

13. The composite shell according to any one of the preceding claims, wherein, The composite shell comprises sheet molding material "SMC" and / or bulk molding material "BMC", wherein the molding material has at least a portion of a nonwoven fabric made of recycled fibers.

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