Multiaxial products with at least two 0° layers

Abstract

The present invention relates to a multiaxial product having at least three yarn layers, each formed by multifilament reinforcing yarns arranged in the yarn layer so as to be parallel to and adjacent to one another, wherein at least two yarn layers are arranged in the multiaxial product to define a 0° direction in the multiaxial product, and at least one additional yarn layer is arranged at an angle of more than ±10° relative to the 0° direction in the multiaxial product, and the at least two 0° oriented yarn layers immediately follow one another, without any additional layers of multifilament reinforcing yarns therebetween, based on the relative arrangement of the at least three yarn layers in the multiaxial product. The present invention also relates to a method for producing the multiaxial product. The present invention further relates to a composite material produced from the multiaxial product, and to a method for producing a composite material from the multiaxial product.

Description

[Technical field]

[0001] Detailed description of the invention: The present invention relates to a multiaxial product comprising at least three layers of yarn.

[0002] Multi-axis products have been known for a long time.

[0003] For example, EP 2547816 or EP 2547510 describe multiaxial products having multiple layers with different angles to each other within the multiaxial product.

[0004] However, a disadvantage of known multiaxial products is that the mechanical properties of the multiaxial product can only be adjusted to a small extent. For example, the application of pressure in the 0° direction of a multiaxial product is strongly dependent on the surface weight of the yarn layer in the 0° direction. An increase in the surface weight would result in an improvement of the mechanical properties. However, the surface weight cannot be increased without problems. A high surface weight often generates a shift of the fibers or a compaction of the fibers in the layer (so-called waviness), so that the yarn layer or an adjacent layer contains wrinkles. This wrinkle in turn reduces the mechanical properties of the yarn layer.

[0005] From EP 3023241 a fiber-reinforced material is known which can be composed of tape material, the different layers of which can be deposited at an angle to one another. According to this document, the tapes are arranged at a distance from one another (they form separate channels). Thus, yarn-free areas arise, so that the mechanical properties of the material are affected.

[0006] It is therefore an object of the present invention to provide a multi-axis product which can be better adapted to the mechanical properties.

[0007] This problem is solved by a multiaxial product having at least three thread layers, each of which is formed by multifilament reinforcing yarns arranged in the thread layers such that they are parallel to one another and adjacent to one another, at least two thread layers are arranged in the multiaxial product so as to define a 0° direction in the multiaxial product, and at least one further thread layer is arranged at an angle of more than ±10° to the 0° direction in the multiaxial product, and the at least two thread layers in the 0° direction follow one after the other immediately after each other without any further layers of multifilament reinforcing yarns interposed therebetween, based on the relative arrangement of the at least three thread layers in the multiaxial product.

[0008] By using at least two yarn layers of 0° orientation immediately following one another in the multiaxial product (without further layers of multifilament reinforcing yarns as yarn layers in between), the mechanical properties of the multiaxial product can be advantageously influenced. For example, the at least two yarn layers of 0° orientation can be composed of different multifilament reinforcing yarns, with the different yarn types being unable to adversely affect each other, or only to a small extent, since they are not present in one layer.

[0009] The at least one further thread layer at an angle of more than ±10° relative to the 0° direction in the multiaxial product preferably has an angle of ±30°, ±45°, ±60° and / or 90° relative to the 0° direction in the multiaxial product. However, the at least one further thread layer at an angle of more than ±10° relative to the 0° direction is not actually a thread layer that is supposed to be deposited in the 0° direction, nor is it a thread layer that is deposited at an angle slightly deviated from the 0° direction only due to imprecision. The at least one further thread layer at an angle of more than ±10° relative to the 0° direction will likewise be described below only as at least one further thread layer.

[0010] To clarify: a multiaxial product may contain multiple yarn layers made of multifilament reinforcing yarns. However, according to the invention, between at least two yarn layers forming a 0° layer, there is no layer made of multifilament reinforcing yarns having an angle of at least ±10° to the 0° layer (i.e. there are no further yarn layers). As a result, between the 0° oriented yarn layers, there can only be so-called intermediate layers, such as nonwoven layers. In this regard, each layer with fibers having a strength of less than 2000 MPa and / or a predominantly non-parallel fiber arrangement within the layer (e.g. nonwoven layers, randomly oriented fiber layers) should be considered as an intermediate layer.

[0011] The thread layers preferably consist of spread multifilament reinforcing threads, which can also be described as tapes. The tapes preferably have a width of 80-800 mm, particularly preferably 250-360 mm, most particularly preferably 600-700 mm. To produce the thread layers, the spread multifilament reinforcing threads are deposited in such a way that there are substantially no holes (yarn-free areas) in the thread layer. The multifilament reinforcing threads are consequently present in a hole-free manner with respect to one another. In a further preferred embodiment, the at least three thread layers each consist of one unidirectional fabric. In the unidirectional fabric, the multifilament reinforcing threads are also spread and arranged parallel to one another and adjacent to one another, but interwoven with auxiliary threads to increase the stability of the layer. As auxiliary threads, for example, bicomponent hot melt adhesive threads with a titer of 200 dtex can be used.

[0012] Preferably, at least two 0° oriented yarn layers are in direct contact with each other in the multiaxial product. By "direct contact" is meant herein that at least two 0° oriented yarn layers in the multiaxial product are placed on each other without any further intermediate layer (not even a nonwoven layer) between the at least two 0° oriented yarn layers.

[0013] Preferably, at least two layers of yarn in the 0° direction each have a density of at least 100 g / m2 , more preferably at least 150 g / m 2 , particularly preferably at least 180 g / m 2 In a preferred embodiment, all the yarn layers in the 0° direction have the same surface weight. However, it would also be conceivable that at least two yarn layers in the 0° direction have different surface weights. Since at least two yarn layers in the 0° direction are used in the multiaxial product, advantageously a high surface weight can be achieved in the 0° direction, for example increasing the compressive strength in the 0° direction. However, compared to using one single layer with a high surface weight, the advantage is obtained that, for example, no or only little yarn waviness occurs in the individual yarn layers in the 0° direction or in their adjacent layers.

[0014] Preferably, at least one further yarn layer has a yarn density of at least 100 g / m 2 , particularly preferably at least 120 g / m 2 When multiple such additional yarn layers are used, all the yarn layers may each have the same surface weight or may have different surface weights.

[0015] Preferably, the at least three yarn layers have as multifilament reinforcing yarns carbon fibres, glass fibres, aramid yarns and / or highly oriented UHMW-polyethylene yarns or a combination of the above yarns. Particularly preferably, the at least three yarn layers constitute up to at least 90% of the above fibres or yarns or the above fibres or yarn combinations.

[0016] In a preferred embodiment, at least two of the thread layers in the 0° direction have the same fiber or thread type as at least one further thread layer. The different thread layers may be identical or different in terms of the thread strength used.

[0017] Preferably, the multifilament reinforcing yarn is a carbon fiber yarn having a strength of at least 5000 MPa, measured according to JIS-R-7608, and a tensile modulus of at least 260 GPa, measured according to JIS-R-7608. For the carbon fiber yarn used, reference is made to the not yet published Japanese application having the application number JP 2017-231749. More preferably, the multifilament reinforcing yarn is a carbon fiber yarn having a strength of at least 4500 MPa, measured according to JIS-R-7608, and a tensile modulus of at least 240 GPa, measured according to JIS-R-7608.

[0018] Preferably, the multiaxial product has at least one nonwoven layer. Preferably, the at least one nonwoven is arranged above, below and / or between the at least three thread layers. Particularly preferably, a nonwoven is arranged between each thread layer and / or the multiaxial product has a further nonwoven on the upper and / or lower side, respectively. In this regard, it should become clear that a nonwoven can also be arranged between two thread layers of 0° orientation that immediately follow each other (in the multiaxial product) in sequence, based on the relative arrangement of the at least three thread layers (except for the example of the embodiment in which the thread layers of 0° orientation are in direct contact with each other). Further preferably, the multiaxial product has a powder binder. For example, the nonwoven can have a powder binder. Preferably, the at least one nonwoven has a binder of 3 to 25 g / m 2 In embodiments using more than one nonwoven, all nonwoven layers used may have the same surface weight or different surface weights. A particularly preferred structure for a multiaxial product is as follows: at least one further layer of yarn Non-woven fabric at least one further layer of yarn Non-woven fabric 0° oriented ply Non-woven fabric 0° oriented ply Nonwoven fabric with powder binder

[0019] In one embodiment, the multiaxial product comprises a metal mesh. Preferably, the metal mesh is arranged above and / or below the at least three yarn layers. Preferably, the metal mesh forms the outermost layer of the multiaxial product. Particularly preferably, the metal mesh has a density of 50 to 250 g / m 2 , particularly preferably 70 to 175 g / m 2 , most particularly preferably 90 to 139 g / m 2 The metal mesh has a surface weight of 0.01 mm. The metal mesh is preferably connected with one or more thread layers, for example by stitches or by a knitted yarn system that holds the multiaxial product together. The metal mesh can advantageously improve the conductivity of the multiaxial product, which is particularly advantageous for applications in the fields of aviation and space travel. Preferably, the metal mesh is a copper mesh.

[0020] Preferably, the at least one nonwoven fabric is comprised of at least a first thermoplastic polymer component and a second thermoplastic polymer component, the first and second polymer components having different melting points.

[0021] Preferably, the polymer component having the lower melting point has a melting point in the range of 80 to 135°C and / or the polymer component having the higher melting point has a melting point in the range of 140 to 250°C.

[0022] Preferably, the first polymer component is soluble in an epoxy, cyanate ester or benzoxazine matrix resin, or in a mixture of these matrix resins, and the second polymer component is insoluble in an epoxy, cyanate ester or benzoxazine matrix resin, or in a mixture of these matrix resins.

[0023] In one embodiment, the first polymer component is a polyamide and / or the nonwoven fabric comprises an epoxide. Particularly preferably, the epoxide is present in the form of a powder binder dispersed on and thermally coupled with the nonwoven fabric.

[0024] To the extent that the binding material is used in particulate form in some embodiments, the preferred particle size is in the range of 50 to 160 μm, particularly preferred 80 to 140 μm.

[0025] In all embodiments using nonwoven fabrics, when two or more nonwoven layers are used, different or the same nonwoven fabrics can be used in the multiaxial product, respectively. When different nonwoven layers are used, the nonwoven layers can differ in terms of their surface weight, their material and / or their structure.

[0026] Compared to previously known multiaxial products, the proposed multiaxial product has the advantage of having a uniform yarn pattern and at the same time a high fiber volume ratio, since the risk of swell is reduced. This allows to increase the compressive strength of the multiaxial product in particular. In addition, the proposed multiaxial product can be draped more easily compared to multiaxial products with a comparable surface weight but with fewer yarn layers, as well as by using pre-fixed 0° layers (e.g. UD tape fixed by weft yarns, powder binder or thermoplastic mesh).

[0027] A further subject of the invention relates to a method for producing a multi-axis product as described above.

[0028] To produce a multiaxial product, at least three yarn layers are deposited, each of the yarn layers being formed by multifilament reinforcing yarns arranged in the yarn layer so as to be parallel to and adjacent to one another, and in the production of the multiaxial product, at least two yarn layers are deposited in a 0° direction, and above and / or below all of the at least two yarn layers in the 0° direction, at least one further yarn layer is deposited at an angle of more than ±10° relative to the 0° direction in the multiaxial product.

[0029] The at least three yarn layers for producing the multiaxial product can be initially formed during the production of the multiaxial product (online) or can be pre-deposited as a prefabricated product (e.g., tape) for producing the multiaxial product as a finishing layer in the manufacturing process (offline).

[0030] At least two thread layers in the 0° direction are stacked on top of each other (with multifilament reinforcing yarns arranged at an angle of more than ±10° relative to the 0° direction) without any further thread layers in between. As a result, at least one further thread layer can be arranged above or below the at least two thread layers in the 0° direction. If two or more further thread layers are used, the further thread layers are located above and / or below the thread layers in the 0° direction, but never between them. When using two or more further thread layers, the multiaxial product thus produced can have a symmetrical structure with respect to the at least two thread layers in the 0° direction. A symmetrical structure with respect to the 0° direction exists, for example, in the case of a multiaxial product having the following structure: +45° / 0° / 0° / -45°

[0031] Preferably, when producing a multiaxial product, at least one nonwoven layer is deposited between one of the yarn layers. Preferably, a nonwoven layer is deposited between all yarn layers and / or as the last layer on one or both sides of the outer yarn layer. For the nonwoven used as the nonwoven layer, reference should be made to the above-mentioned embodiment regarding the nonwoven of the multiaxial product.

[0032] In an example embodiment, a metal mesh can further be deposited on the outside of the multiaxial product, the design of which refers to what has already been described for the metal mesh of the multiaxial product.

[0033] In a preferred embodiment, each of the at least two plies deposited in the 0° direction is deposited by one deposition device, respectively. When using prefabricated plies, the result is that one deposition device with a wound-up ply is used for each ply in the 0° direction.

[0034] In another embodiment, at least two yarn layers in the 0° direction are each produced by one standing yarn creel when supplied with an online feed in producing a multiaxial product.

[0035] In a further embodiment, when producing a multiaxial product, at least two 0° oriented yarn layers are deposited as a so-called unidirectional fabric. During production, each unidirectional fabric is then laid down as a 0° oriented yarn layer, preferably by its own deposition device during the production process.

[0036] A further subject of the invention relates to a fiber-reinforced composite material comprising at least one multiaxial product according to the above. Preferably, the composite material has multiple yarn layers of multifilament reinforcing yarns and nonwoven layers between them. Particularly preferably, the composite material has a further or additional matrix material with which the yarn layers and the nonwoven layers are impregnated.

[0037] A further subject of the invention is therefore also a method for producing a composite material with additional matrix material. Preferably for this purpose, a number of multiaxial products of the type mentioned at the beginning are laminated together and consolidated by heat and pressure and additional matrix material to form a component (composite material). This type of composite material can be used, for example, as a component in the field of aviation and space travel or in the automotive field.

Claims

1. 1. A multiaxial product having at least three yarn layers, each of said yarn layers being formed by multifilament reinforcing yarns arranged in said yarn layers so as to be parallel to one another and adjacent to one another, said yarn layers consisting of spread multifilament reinforcing yarns and having no matrix material, at least two yarn layers being arranged in said multiaxial product to define a 0° direction in said multiaxial product, and at least one further yarn layer being arranged at an angle of more than ±10° relative to the 0° direction in said multiaxial product, said at least two yarn layers in the 0° direction immediately following one another in sequence without an intervening further layer of multifilament reinforcing yarn therebetween based on the relative arrangement of said at least three yarn layers in said multiaxial product, and said multifilament reinforcing yarns being interwoven with hot melt adhesive yarns.

2. The at least two yarn layers in the 0° direction each have a fiber density of at least 150 g / m ２ 2. The multi-axis article of manufacture of claim 1 having a surface weight of

3. The at least one further yarn layer arranged at an angle of more than ±10° to the 0° direction in the multiaxial product each has a fiber density of at least 100 g / m ２ 3. The multi-axis product of claim 1 or 2, having a surface weight of

4. 4. A multiaxial product according to claim 1, wherein the multifilament reinforcing yarns are carbon fibre, glass fibre or aramid yarns or highly oriented UHMW-polyethylene yarns.

5. The multifilament reinforcing yarn is a carbon fiber yarn having a strength of at least 5000 MPa, measured according to JIS-R-7608, and a tensile modulus of at least 260 GPa, measured according to JIS-R-7608. A multiaxial product according to any one of claims 1 to 4.

6. The multifilament reinforcing yarn is a carbon fiber yarn having a strength of at least 4500 MPa, measured according to JIS-R-7608, and a tensile modulus of at least 240 GPa, measured according to JIS-R-7608. The multiaxial product according to any one of claims 1 to 4.

7. 7. The multiaxial product according to claim 1, wherein at least one nonwoven fabric is arranged above, below and / or between the at least three yarn layers and / or at least one metal mesh is arranged above and / or below the at least three yarn layers.

8. The at least one nonwoven fabric has a density of 3 to 25 g / m ２ and / or said metal mesh has a surface weight in the range of 60 to 200 g / m ２ 8. The multi-axis article of manufacture of claim 7 having a surface weight of

9. 9. The multiaxial product of claim 7 or 8, wherein the at least one nonwoven fabric is comprised of at least one first thermoplastic polymer component and one second thermoplastic polymer component, the first and second polymer components having different melting points.

10. 10. The multi-axis article of claim 9, wherein the polymer component having the lower melting point has a melting point in the range of 80 to 135°C and / or the polymer component having the higher melting point has a melting point in the range of 140 to 250°C.

11. 11. The multiaxial product of claim 9 or 10, wherein the first polymer component is a polyamide and / or the nonwoven fabric comprises an epoxide.

12. 11. The multi-axis article of manufacture of claim 10, wherein the first polymer component is soluble in an epoxy, cyanate ester or benzoxazine matrix resin, or in a mixture of these matrix resins, and the second polymer component is insoluble in an epoxy, cyanate ester or benzoxazine matrix resin, or in a mixture of these matrix resins.

13. 13. The multiaxial product according to any one of claims 1 to 12, wherein the at least one nonwoven fabric has a binding material in granular form, the particle size of the binding material being between 50 and 160 μm.

14. A fiber-reinforced composite material comprising at least one multiaxial product according to any one of claims 1 to 13.

15. 2. A method for producing a multiaxial product according to claim 1 from at least three yarn layers, each of which is formed by multifilament reinforcing yarns arranged in said yarn layers so as to be parallel to each other and adjacent to each other, wherein during the production of the multiaxial product at least two yarn layers are deposited in a 0° direction, and above or below all of the at least two yarn layers in the 0° direction at least one further yarn layer is deposited at an angle of more than ±10° relative to the 0° direction in the multiaxial product.

16. The method of claim 15 , wherein at least one nonwoven fabric is deposited above, below and / or between the at least three yarn layers.

17. 17. The method according to claim 15 or 16, wherein each of the at least two yarn layers deposited in a 0° direction is deposited by one deposition device, respectively.

18. 16. A method for producing a composite material according to claim 15, in which at least one multiaxial product according to any one of claims 1 to 13 and an additional matrix material are used.