Semipreg with matrix coating

Abstract

The present invention relates to a semipreg made from a UD layer, wherein one or both outer layers of the semipreg have a matrix material weighing 30 to 45% by weight relative to the total weight of the semipreg. At least 60% by weight of the matrix material (based on the total weight of the semipreg) penetrates into the semipreg to a depth of less than 100 μm (measured in the thickness direction of the semipreg). Furthermore, the present invention relates to a method for manufacturing a semipreg and a method for manufacturing fiber-reinforced composite components from a semipreg.

Description

Technical Field

[0001] The present invention relates to a prepreg having at least two unidirectional fiber layers and a matrix coating according to the preamble of claim 1.

[0002] Unidirectional fiber layers (UD layers) are known. UD layers that form prepregs when impregnated with a matrix material are also known. In a prepreg, the matrix material is usually located inside the fiber material. Preferably, the matrix material in the fiber material of the prepreg is uniformly distributed, so that the matrix material is present throughout the fiber material at approximately the same ratio.

[0003] U.S. Patent Application Publication No. 2009 / 0068428 describes a type of fabric having an adhesive layer on at least one side. Most of the fabric layers are joined to each other by the adhesive layer. The fabric has reinforcing fibers in one direction, into which auxiliary yarns are woven. The adhesive content on at least one surface of the fabric should not exceed 40 g / m 2 and then the resulting material is impregnated with a matrix material.

[0004] German Patent Application Publication No. 102011084626 discloses a fiber-reinforced composite material intended for use as a clutch disk. The composite material has at least two superimposed layers of carbon fibers, and the layers are impregnated with a matrix.

[0005] U.S. Patent Application Publication No. 2012 / 0100354 describes a fiber-reinforced material formed from NCF and containing carbon fibers. The material is further processed later with a matrix material, and the NCF layers are stitched together.

[0006] European Patent No. 3705215 describes a method for impregnating a fabric to produce a prepreg, where the fabric may be, for example, a UD material. In this process, process parameters such as contact pressure can be adapted to different surface structures and different matrix materials used, thereby achieving optimal impregnation or permeation. Impregnation can be carried out on one side or both sides.

[0007] A drawback of known materials is that when components (e.g., fiber-reinforced composite components) are manufactured from the material, a matrix material usually has to be added to the material. If the material already has a corresponding amount of matrix material (in the form of a prepreg), the matrix material is integrated into the fiber layer, and the material is generally not very drapeable as a prepreg.

[0008] U.S. Patent Application Publication No. 2022 / 0388274 also describes the use of fiber layers, for example, in the form of a nonwoven fabric or a UD fiber layer. A matrix layer is provided on one side in direct contact with the fiber layer and is intended to connect the superimposed fiber layers. The matrix layer is intended to achieve bonding of the two fiber layers by impregnating the two fiber layers. As a result, the matrix material must be able to penetrate from the matrix layer into both fiber layers, completely into at least adjacent fiber layers (from the arrangement of the matrix layer), and at least partially into more distant fiber layers. According to the text, the material may contain 20 to 50% by weight of matrix material.

[0009] Japanese Patent Publication No. 2018065999 proposes a reinforced fiber material that may also include a matrix material. The reinforcing fibers can be present in the fiber aggregate, and in particular, a sewn UD structure is also taught. As shown in Figure 1, the matrix material is provided on one side of the fiber aggregate. Preferably, the matrix material should remain on the surface of the fiber aggregate in a proportion of 50 to 70% by weight. Depending on the selected shape of the fiber aggregate and the selected matrix material, the matrix material should not impregnate the fiber aggregate beyond 15 to 97 μm. The matrix material content should be 1 to 20% by weight to improve the dimensional stability and impregnation of the material.

[0010] A drawback of this conventional technology is that the process for manufacturing the components still requires the addition of a corresponding amount of matrix material.

[0011] Therefore, the object of the present invention was to provide a semi-prepreg that already has the matrix content necessary for the manufacture of the constituent elements, but is still easily drapeable.

[0012] This problem is solved by a semipreg having the features of claim 1. The semi-prepreg according to claim 1 has at least two fiber layers, each fiber layer being a so-called UD fiber layer (and therefore not a woven fabric). In a UD fiber layer, the fibers within the fiber layer are parallel to each other and in contact with each other (without gaps). The at least two fiber layers form the outer layer of the semi-prepreg, and as a result, each fiber layer has an outer surface. The at least two fiber layers can be laid overlapping each other such that the fiber orientations of both fiber layers are essentially parallel to each other, or the fiber orientations of the different fiber layers are at angles other than 0° to each other. Furthermore, the fiber layers are sewn together perpendicular to the plane in which the reinforcing fibers of the fiber layers are present. Thus, the sewing is carried out in the thickness direction of the semi-prepreg being formed, or of the at least two fiber layers. The semi-prepreg has a matrix material with a matrix content of 30-45% by weight relative to the total weight of the semi-prepreg. Preferably, the semi-prepreg has a matrix content (30-45% by weight) based on the total weight of the fiber layers formed from the reinforcing fibers. Therefore, the matrix material content is sufficient to produce fiber-reinforced composite components from the semi-preg without requiring additional (often complex and lengthy) matrix impregnation (e.g., in the form of matrix injection) during component manufacturing. However, the matrix material components are located on only one top and / or one bottom surface of the semi-preg (i.e., the outer surface of the fiber layer). Furthermore, the matrix material hardly penetrates into the semi-preg. At least 60% by weight of the total matrix material penetrates into the semi-preg to a depth of less than 100 μm, and the penetration depth is measured substantially perpendicular (at an angle of 80° to 95°) to the propagation direction of the reinforcing fibers in the fiber layer and in the thickness direction of the semi-preg. Thus, the fiber material does not completely penetrate into the matrix material in the semi-preg, and only a small percentage by weight of the matrix material (less than 40% by weight) penetrates deeper than 100 μm into the semi-preg.In a semi-prepreg in which at least 60% by weight of the matrix material penetrates to a depth of less than 100 μm, it should be clarified that 60% by weight of the matrix material penetrates to a depth of less than 100 μm into the fiber layers forming the outer layer, or into both fiber layers forming the outer layer if the matrix material is applied to both outer surfaces. This has the advantage of allowing the semi-prepreg to remain drapeable, as the fiber layers remain movable relative to each other. It was quite surprising that such a high proportion of matrix could be bonded to the semi-prepreg via the fiber layers, even at such a shallow penetration depth. When using more than two fiber layers, at least two fiber layers form the outer layer of the semi-prepreg, and the remaining fiber layers are located inside the semi-prepreg. It is preferable that the remaining fiber layers within the semi-prepreg do not contain matrix material.

[0013] When the matrix material is completely permeated into the fiber layer, the semi-prepreg is essentially air-free and has a porosity of less than 10% (preferably 4% to less than 2%).

[0014] However, the semipreg having the features of claim 1 should preferably have a porosity of more than 10%, preferably more than 15%, more than 20%, more than 30%, more than 40%, more than 50%, more than 60%, more than 70%, more than 80%, or more than 90%.

[0015] A semi-prepreg having the matrix material content described in claim 1 can be referred to as a so-called non-crimped fabric (NCF) semi-prepreg.

[0016] A semi-preg is defined as a woven fiber material containing between 25% and up to 60% by weight of matrix material based on the total weight of the semi-preg, preferably in the form of a UD fiber layer, where the matrix material is not uniformly distributed in the fiber material (i.e., in the fiber layer), but the majority of the fiber material does not contain matrix material. The outer surface of the semi-preg is formed by the outer surface of the fiber material, i.e., the fiber layer.

[0017] In one embodiment of a semi-prepreg, the matrix material is applied to the semi-prepreg by coating (e.g., by dipping, powdering, and / or melting).

[0018] Preferably, at least 60% by weight of the total matrix material penetrates into the fiber layer to a depth of less than 70 μm, preferably less than 50 μm, preferably less than 40 μm, preferably less than 30 μm, preferably less than 25 μm, and more preferably less than 20 μm, and the penetration depth is measured substantially perpendicular (at an angle of 80° to 95°) to the propagation direction of the reinforcing fibers within the fiber layer. In one embodiment of the semi-prepreg, at least 90% by weight of the total matrix material penetrates the fibrous layer of the semi-prepreg to a depth of less than 70 μm, preferably less than 50 μm, preferably less than 40 μm, preferably less than 30 μm, preferably less than 25 μm, and more preferably less than 20 μm, where the penetration depth is measured substantially perpendicular (at an angle of 80° to 95°) to the propagation direction of the reinforcing fibers within the fibrous layer.

[0019] In embodiments where both outer surfaces of the semi-prepreg are made of matrix material, the above disclosed information regarding the penetration depth of the matrix material and the percentage of the permeating matrix material shall apply to each individual outer surface of the corresponding fiber layer. Different outer surfaces of different fiber layers may have the same penetration depth and percentage of the permeating matrix material, or different penetration depths and percentages. Therefore, as described, the semi-prepreg has a sufficient matrix material content for component manufacturing without the matrix material completely permeating the semi-prepreg before component manufacturing. In the semi-prepreg according to claim 1, where the matrix material is not completely permeated, only one or both outer surfaces have the matrix material. In particular, the center of the semi-prepreg, i.e. (in a structure having only two fiber layers) the region where the two fiber layers are in contact, does not contain the matrix material. This allows for high mobility between at least two fiber layers, thereby improving the drape and formability of the semi-prepreg. In semi-prepregs having more than two fiber layers, the fiber layer located in the center in the thickness direction must not contain the matrix material. For example, in a semi-prepreg formed from four layers of fibers stacked on top of each other, the second and third layers of fibers preferably do not contain the matrix material (similarly the region between the second and third layers of fibers). Therefore, the semi-prepreg always contains fiber material that does not contain the matrix material. In this context, the term “not containing the matrix material” does not mean that the fibers in the fiber layer cannot have so-called sizing (from the beginning). Sizing is used particularly for carbon fibers to improve the processing of the fibers, and can reach up to 6% by weight, preferably as little as 3% by weight, and even more preferably as little as 1.5% by weight, of the total weight of the fiber layer. For sizing, for example, epoxy resins, thermoplastic resins, or mixtures thereof can be used.

[0020] In one embodiment, the entire matrix material is provided as a continuous, flat surface on the outer surface. "Fully coated" means that there are essentially no portions of the surface area of ​​the corresponding outer surface (which is thought to contain the matrix material) that do not contain the matrix material. Preferably, at least 80%, preferably at least 90%, and all of the coated outer surface is covered with the coating. It is particularly preferable that 100% of the outer surface is coated with the matrix material. The full surface coating allows the semipreg to slide or adhere particularly well on other or similarly structured semipregs (depending on the properties of the matrix material used).

[0021] In another embodiment, the entire matrix material is distributed discontinuously across the outer surface of the semi-prepreg. This discontinuous distribution is particularly present when the matrix material is not distributed across the entire surface of the outer surface. For example, the matrix material can be distributed across the outer surface in the form of islands or aggregates, most of which are not interconnected (achievable, for example, by powder impregnation). Such a matrix distribution has the advantage that the drape can be further improved because the semi-prepreg remains more flexible overall.

[0022] In one embodiment, the matrix material is not present on any of the outer surfaces as a grid, mesh, or nonwoven material.

[0023] In one embodiment, matrix material is provided on both outer surfaces of the semi-prepreg, preferably the amount of matrix material on the first outer surface is equal to the amount of matrix material on the second outer surface. This advantageously results in a homogeneous structure of the semi-prepreg, which can simplify the production of fiber-reinforced composite components from the semi-prepreg. For example, fiber-reinforced composite components can be produced from a semi-prepreg by bonding the semi-prepreg to the fiber-reinforced composite component under pressure and heating in a mold, thereby allowing the existing matrix material to flow uniformly through the semi-prepreg, thereby completely impregnating the semi-prepreg. With a homogeneous structure, the direction of insertion of the semi-prepreg into the mold for component production is not important. This can be advantageous in avoiding manufacturing defects and reducing waste.

[0024] In another embodiment, both outer surfaces have matrix material, but the amount of matrix material on the first outer surface is not equal to the amount of matrix material on the second outer surface. In such a setup, gravity can be used to manufacture the components, for example, if the outer surface with a high matrix material content is placed on the upper surface of the mold, and the matrix material can flow downward with the help of gravity to manufacture the components.

[0025] The matrix material for coating one or both outer surfaces of the semi - prepreg may be, for example, a thermoplastic resin, a thermosetting resin, or a mixture of a thermoplastic resin and a thermosetting resin. In one embodiment, the matrix material comprises polyether ether ketone or, preferably, only polyether ether ketone is used as the matrix material. In one embodiment, the matrix material comprises polyphenylene sulfide (PPS) or, preferably, only polyphenylene sulfide is used as the matrix material. In one embodiment, the matrix material comprises polyether imide (PEI) or, preferably, only polyether imide is used as the matrix material. In one embodiment, the matrix material comprises polyaryl ether ketone (PAEK) or, preferably, only polyaryl ether ketone is used as the matrix material. When only one of the aforementioned matrix materials is used, this means that 95 - 100%, preferably 100% of the matrix material is the aforementioned material.

[0026] In one embodiment, the matrix material for coating one or both outer surfaces is either a thermoplastic resin or a thermosetting resin, and both the thermoplastic resin and the thermosetting resin each consist of less than 6, less than 4, and less than 3 individual components respectively.

[0027] In one embodiment, the matrix material is applied as a powder to one or both outer surfaces of the semi - prepreg, to the corresponding outer surfaces of the fiber layer. The powder preferably has an average particle size of 20 - 100 μm, preferably 25 - 50 μm. In another embodiment, the matrix material is applied by a dipping bath, and the average particle size of the matrix material in the dipping bath is also 20 - 100 μm, preferably 25 - 50 μm. In another embodiment, the application of the matrix material to one or both outer surfaces of the semi - prepreg can also be carried out by a combination of powder coating and dipping using a matrix material having the average particle size of the matrix material as described above.

[0028] In another embodiment, the semi - prepreg has additional unidirectional fiber layers and / or non - woven layers between the outer layers. For example, the semi - prepreg can have four fiber layers, and non - woven layers are disposed between each pair of the fiber layers (i.e., in the example of having four fiber layers, three non - woven layers). Preferably, the non - woven layer is a random fiber non - woven layer made from a thermoplastic fiber material having a basis weight of less than 5 g / m 2 The fiber layers can preferably be symmetrically arranged within the semi - prepreg, for example, having the following layer structure: 90° / - 45° / + 45° / 90°.

[0029] In another embodiment of the semi - prepreg, the carbon fibers of at least two fiber layers are substantially uncorrugated within the fiber layer. Thus, the stitches between the fiber layers are selected so that layer undulations of the fiber layers do not occur. Experts recognize that, inter alia, from European Patent No. 2547816, sewing must be adapted with respect to stitch length and stitch width, taking into account the fineness of the reinforcing fibers, the angle of the reinforcing fibers within the layer, and the thread count of the sewing thread.

[0030] According to another embodiment of the semi - prepreg, at least two fiber layers within the semi - prepreg have an angle of 0° / 90°, + 45° / 135°, 30° / 150° or 20° / 60° with each other, or at least two fiber layers are laid within the semi - prepreg in combinations of the aforementioned angles with each other.

[0031] Another aspect of the present invention relates to a method for manufacturing a semi - prepreg having the features described in claim 1. Thus, the description of the semi - prepregs should also apply to the method as far as they are relevant. On the other hand, the description of the method should also apply to the semi - prepregs as far as they are appropriate.

[0032] In a method for producing a semi-prepreg, preferably, at least two fiber layers are first formed from reinforcing fibers, and the reinforcing fibers within each layer are parallel to each other in one direction. Then, the UD (unidirectional) layers of reinforcing fibers are laid overlapping each other so that the main propagation directions of the fibers in the different fiber layers can form an angle of 0° or more relative to each other. A nonwoven material can be provided between at least two layers of reinforcing fibers. In one embodiment of the method for producing a semi-prepreg, at least two reinforcing fiber layers are sewn together (in the thickness direction) before the matrix material is applied. The sewing is preferably carried out so that the sewing thread is located beneath the loops formed between the overlapping fiber layers. In one embodiment of the method, the reinforcing fibers in each fiber layer are further sewn together within the fiber layer so that the reinforcing fibers in the fiber layer are less likely to displace each other within the fiber layer. In one embodiment, the sewing thread is made from a material that melts into the matrix material used (without forming its own phase) during subsequent processing of the components of the semi-prepreg, or from a material that has a higher melting temperature than the matrix material and therefore remains largely intact during impregnation. In one embodiment, the sewing thread can be made from the same material as the matrix material to be applied. Preferably, the matrix material is applied to the first and / or second outer surface of the semipreg thus formed by powder impregnation, powder coating, foulard, squeegee and / or film transfer.

[0033] In one embodiment of a method for manufacturing a semi-prepreg, a matrix material is first applied to the first and / or second fiber layers of at least two fiber layers, and then the at least two fiber layers are laid on top of each other to form a semi-prepreg. In this case, the layer arrangement is such that the matrix material is present as the outer surface of the semi-prepreg. The different fiber layers are then sewn together (penetrating the matrix layer as well).

[0034] Another aspect of the present invention relates to a method for manufacturing fiber-reinforced composite materials. The fiber-reinforced composite material (component) is preferably formed solely from one or more semi-prepregs described herein. Methods for manufacturing fiber-reinforced composite components are also appropriately applied to the descriptions relating to the manufacture of semi-prepregs or semi-prepregs. Preferably, the fiber-reinforced composite material is manufactured from semi-prepregs (or multiple semi-prepregs) without the addition of further matrix material, and the semi-prepregs (or multiple semi-prepregs) are formed into a fiber-reinforced composite material under pressure and heating. Therefore, the matrix material required for manufacturing the component (fiber-reinforced composite component) is provided solely by the semi-prepregs and does not need to be introduced by further method steps, such as matrix injection. This simplifies the manufacturing method and reduces processing time.

[0035] Preferably, the components are formed from a single semi-preg, characterized by being predominantly made up of UD fiber layers. Depending on the components, the number of UD fiber layers may vary, and therefore the matrix material content on one or both outer surfaces of the semi-preg may also vary.

[0036] When forming a component from two semi-prepregs, the two semi-prepregs are preferably positioned relative to each other for the fabrication of the composite material such that the matrix material is present on the outer surface of the composite material to be manufactured. In this example, a semi-prepreg with the matrix material on only one of its outer surfaces is used.

[0037] When forming components from more than two semi-prepregs, or when using exactly two semi-prepregs, in one embodiment, the semi-prepregs in the composite material to be manufactured can also be arranged such that one or more matrix material layers are present within the composite material to be manufactured. For this purpose, for example, when using more than two semi-prepregs, one (or more) semi-prepregs having matrix material on their outer surface can be placed between two or more semi-prepregs having matrix material on their outer surface and processed into a composite material. The present invention is further described below with reference to the drawings and embodiments, which merely illustrate exemplary embodiments of the invention. This is not intended to limit the scope of protection of the invention. [Brief explanation of the drawing]

[0038] [Figure 1] This diagram schematically shows a semi-prepreg with a matrix coating, where the matrix coating is present only on the outer surface of the semi-prepreg. [Figure 2] This is a microscopic image of a semi-prepreg with a powder coating. [Figure 3] This is a microscopic image of the semipreg at a different magnification than Figure 2.

[0039] Figure 1 schematically shows semipreg 1, which consists of five UD fiber layers made from multifilament-reinforced fibers. Within each UD fiber layer, the reinforcing fibers are parallel to each other, and there are essentially no fiber-free regions within the UD layer. The semi-prepreg 1 has two outer surfaces extending parallel to the main stretching plane of the UD fiber layer. On one of the outer surfaces, the semi-prepreg in Figure 1 has a matrix material 2. In the embodiment shown in Figure 1, the matrix material 2 is applied as a powder to the outer surface of the semi-prepreg 1. The application process involves applying the matrix material to the outer surface of the UD fiber layer, which then forms the outer surface of the semi-prepreg 1. This involves applying 30-45% by weight of the matrix material based on the total weight of the semi-prepreg. If the semi-prepreg consists only of the UD fiber layer and the matrix material, the weight specification (30-45% by weight based on the semi-prepreg) is also a specification of 30-45% by weight based on the total weight of the fiber layer. The matrix material 2 hardly penetrates into the UD fiber layer that constitutes the outer surface. Thus, advantageously, the matrix material is located mainly on the surface of the outer surface. Preferably, less than 40% by weight of the total matrix material penetrates deeper than 100 μm in the thickness direction into the fiber layer of the semi-prepreg 1. Preferably, at least 60% by weight of the total matrix material penetrates to a depth of less than 20 μm in the thickness direction into the fiber layer of the semi-prepreg 1. Preferably, at least 90% by weight of the total matrix material penetrates to a depth of less than 100 μm in the thickness direction into the fiber layer of the semi-prepreg. Preferably, at least 90% by weight of the total matrix material penetrates to a depth of less than 20 μm in the thickness direction into the fiber layer of the semi-prepreg. In one embodiment, at least 90% by weight of the total matrix material penetrates to a depth of less than 10 μm in the thickness direction into the fiber layer of the semi-prepreg. The fiber layer of the semi-prepreg containing the matrix material is the outer layer of the semi-prepreg. For example, if 90% by weight of the total matrix material penetrates into the fiber layer of the semi-preg to a depth of less than 20 μm in the thickness direction, then 90% by weight of the total matrix material also penetrates into the semi-preg to a depth of less than 20 μm in the thickness direction. Therefore, matrix material 2 is located only superficially on the fiber layer of semi-preg 1 in the outer region, and the intermediate fiber layer does not contain matrix material 2 at all.This improves the relative mobility between fiber layers, thereby enhancing the drape of the semi-prepreg 1. Therefore, the matrix material within the semi-prepreg does not have to perform stabilization tasks within the semi-prepreg, such as ensuring the aggregation of different (fiber) layers.

[0040] Figure 2 shows a microscopic image of a semi-prepreg 1 having a matrix material 2. The matrix material 2 is essentially located on the outer surface of the semi-prepreg 1 and has little penetration into the fiber layer 3 of the semi-prepreg 1. In the embodiment shown in Figure 2, the matrix material 2 was impregnated into the semi-prepreg 1 with a powder binder. The polymer powder solidified during occlusion and existed on the outer surface of the fiber layer 3 of the semi-prepreg as a kind of matrix material aggregate.

[0041] Figure 3 shows a microscopic image of the same material as in Figure 2, but at a higher resolution. Matrix material 2 is located on top of the fiber layer 3 and has hardly penetrated the fiber layer 3.

[0042] Examples: A carbon fiber-based multiaxial fabric was manufactured using a multiaxial system (Karl Mayer Holding GmbH & Co. KG). For this purpose, individual layers in the form of fiber layers were first manufactured from parallel, adjacent, and in contact carbon fiber yarns of type HTS45 E13 12K 800tex (Teijin Carbon Europe GmbH). Two of these fiber layers were laid overlapping each other such that the lower layer had an angle α of +45° with respect to the manufacturing direction of the multiaxial fabric, and the upper layer had an angle α of -45°. The fiber layers, positioned vertically relative to each other, were woven in the thickness direction of the fabric using tricot sewing thread. In this embodiment, the sewing thread used was made of copolyamide and had a fineness of 33 dtex. The stitch length was 3.6 mm and the stitch width was 5 mm.

[0043] Example 1 Next, the obtained fabric (multiaxial fabric) was impregnated with a matrix material on a single outer surface. In Example 1, the fabric was impregnated using a powder spraying system (Maschinenfabrik Herbert Meyer GmbH). The fabric was supplied to the powder coating area via a deflection roller. The polymer used was PEEK 150 (Victrex Manufacturing Limited) with an average particle size of 10-100 μm. In the powder spraying step, the polymer was uniformly sprayed and then melted using an infrared heating field. The powder coating step was performed twice to provide a uniform coating on both sides of the fabric. After the completion of powder coating, the article was wrapped around a cardboard tube, wrapped in foil, and made available for further processing in the manufacturing of components. The semi-prepreg produced in this manner had a matrix content of 42% by weight relative to the total weight of the semi-prepreg, and 60% by weight of the matrix material penetrated to a depth of 25 μm or less into the fiber layer of the semi-prepreg, as measured from the outer surface containing the matrix material.

[0044] Example 2 In Example 2, the fabric manufactured as described above was impregnated with a matrix material by a dipping impregnation process. The fabric was fed into the impregnation area via a roller. The polymer used was PEEK 150 (Victrex Manufacturing Limited) with an average particle size of 10-50 μm. In the impregnation step, the fabric was guided through a carrier liquid (organic solvent, preferably alcohol or water) and a dispersion of polymer powder, then dried until the material no longer contained the carrier liquid, and then the polymer was melted using an infrared heating field. The semi-prepreg was then wound onto a cardboard tube, wrapped in foil, and made available for further processing into components. This semi-prepreg had a matrix content of 42% by weight relative to the total weight of the semi-prepreg. The matrix material was located on both outer surfaces of the fibrous layer of the semi-preg, with approximately 60% by weight of the total matrix material penetrating from the outer surface into the semi-preg to a depth of 25 μm or less (i.e., approximately 60% by weight of the total matrix material also penetrating to a depth of 25 μm or less into the fibrous layer forming the outer surface of the semi-preg).

Claims

1. A semi-prepreg (1) comprising at least two unidirectional fiber layers (3) of carbon fibers, wherein the carbon fibers within each of the unidirectional fiber layers (3) are arranged parallel to and adjacent to each other, the carbon fibers of adjacent unidirectional fiber layers (3) are laid at angles of 0 to 180° to each other, the semi-prepreg (1) has a matrix material (2) of 30 to 45% by weight based on the total weight of the semi-prepreg (1), one of the at least two unidirectional fiber layers (3) forms a first outer layer of the semi-prepreg (1), the first surface of the fiber layer is the first outer surface of the semi-prepreg (1), and the at least one other unidirectional fiber layer is the second A semi-prepreg (1) characterized in that it forms an outer layer of 2, the second surface of the fiber layer is the second outer surface of the semi-prepreg (1), the first surface and the first outer surface are substantially parallel to the second surface and the second outer surface, the at least two unidirectional fiber layers (3) of carbon fibers are sewn together perpendicular to the main propagation direction of the carbon fibers of the unidirectional fiber layers (3), the entire matrix material (2) is provided on the first and / or second outer surface, and at least 60% by weight of the entire matrix material (2) penetrates from one or more outer surfaces to the semi-prepreg (1) to a depth of less than 100 μm perpendicular to the main propagation direction of the carbon fibers of the unidirectional fiber layers (3).

2. The semipreg (1) according to claim 1, wherein 90% by weight of the total matrix material (2) penetrates from one or more outer surfaces of the semipreg (1) into the semipreg (1) to a depth of less than 20 μm, preferably less than 10 μm, perpendicular to the main propagation direction of the carbon fibers of the unidirectional fiber layer (3).

3. The semipreg (1) according to claim 1 or 2, wherein the matrix material (2) is continuously and / or discontinuously distributed on the outer surface.

4. The semipreg (1) according to any one of claims 1 to 3, wherein the amount of matrix material (2) on the first outer surface is equal to the amount of matrix material (2) on the second outer surface, or the amount of matrix material (2) on the first outer surface is not equal to the amount of matrix material (2) on the second outer surface.

5. The semipreg (1) according to any one of claims 1 to 4, wherein the matrix material (2) is a thermoplastic resin, a thermosetting resin, or a mixture thereof.

6. The semi-prepreg (1) according to any one of claims 1 to 5, wherein the semi-prepreg (1) has a further unidirectional fiber layer (3) and / or a nonwoven fabric layer between the outer layers.

7. The semipreg (1) according to any one of claims 1 to 6, wherein the carbon fibers of the at least two fiber layers (3) are present within the fiber layers (3) without warping.

8. The semipreg (1) according to any one of claims 1 to 7, wherein the at least two fiber layers (3) are laid out together within the semipreg (1) at angles of 0° / 90°, +45° / 135°, 20° / 60°, 30° / 150°, or a combination of the angles.

9. A method for producing a semipreg (1) according to any one of claims 1 to 8, wherein the matrix material (2) is applied to the first and / or second outer surface by powder impregnation, powder coating, fullerd, doctor blade and / or film transfer.

10. The method according to claim 9, wherein first, the at least two unidirectional fiber layers (3) of carbon fibers are laid at angles other than 0° to each other, and then the matrix material (2) is applied.

11. The method according to claim 10, wherein, prior to the coating of the matrix material (2), the at least two fiber layers (3) are sewn together perpendicular to the main propagation direction of the carbon fibers of the unidirectional fiber layer (3).

12. The method according to claim 10, wherein first the matrix material (2) is applied to the first and / or second fiber layer (3) of the at least two fiber layers (3), and subsequently the at least two fiber layers (3) are arranged on the semi-prepreg (1) such that the matrix material (2) is present as the outer surface of the semi-prepreg (1).

13. A method for producing a fiber-reinforced composite material comprising at least one semi-prepreg (1) according to any one of claims 1 to 8, wherein the at least one semi-prepreg (1) is formed into a fiber-reinforced composite material under pressure and heating without the addition of further matrix material.

14. The manufacturing method according to claim 13, wherein, when more than two semipregs (1) are used, the more than two semipregs (1) are arranged in the setup for manufacturing the composite material such that the matrix material is present on the outer surface of the composite material to be manufactured.

15. The manufacturing method according to claim 13, wherein a single semipreg (1) is used for the production of the composite material. a. The manufacturing method according to claim 14, wherein the semi-prepreg (1) has two or more layers of fiber (3) and / or nonwoven fabric material.

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