Spacer fabrics, injection molding composites and methods for producing injection molding composites

Abstract

The invention relates to a spacer fabric (1), in particular for forming an injection-molded composite, comprising a first knitted layer (3) formed by at least one first yarn system (F1) and a second yarn system (F2) of different layups, a second knitted layer (4), and spacer threads (5) connecting the knitted layers (3, 4), wherein the first yarn system (F1) has a loop-forming layup. According to the invention, the ratio of the basis weights of the first knitted layer (3) and the second knitted layer (4) is at least 2:1, and the threads of the second yarn system (F2) do not form loops and each extend as a partial weft over at least four loops.

Description

[0001] The invention relates to a spacer fabric, in particular for forming an injection-molded composite, comprising a first knitted fabric layer formed by at least one first thread system and a second thread system of different layup, a second knitted fabric layer, and spacer threads connecting the knitted fabric layers to one another, wherein the first thread system has a stitch-forming layup. The invention further relates to an injection-molded composite comprising such a spacer fabric and a method for producing an injection-molded composite.

[0002] Spacer fabrics are characterized by a lightweight, breathable structure. They are elastic along their thickness due to the spacer threads running between the two layers. Monofilament yarns are typically used as spacer threads, which, due to their structure, exhibit a comparatively high recovery effect.

[0003] The basics of producing a spacer fabric are known to the expert, and reference is made to the specialist book “Wirkerei und Strickerei”, Markus Oliver Weber / Klaus-Peter Weber, 6th edition 2014 (ISBN 978-3-86641-299-6).

[0004] Due to their elastic properties, spacer fabrics can be used as soft, elastic, and air-circulating layers in mattresses, upholstered furniture, clothing, or shoes. Spacer fabrics are also used as technical textiles in the automotive sector, for example, for climate-controlled seats and seat covers. Their cushioning properties and excellent resilience allow for good contour adaptation.

[0005] In addition, spacer fabrics are particularly suitable for padding in the automotive sector and other applications, such as furniture construction. For example, spacer fabrics are used in the automotive sector for interior trim. Depending on the design, the spacer fabric can then form a visible surface itself or be combined with a covering layer, such as leather, synthetic leather, another textile, or a decorative film.

[0006] The compression-elastic properties of the spacer fabric offer particular advantages in these cases. In addition to a particularly pleasant and high-quality feel, tensions and stresses on the material can be reduced. An additional top layer in the form of leather, synthetic leather, a textile, or a film can exert a certain amount of compression, thereby significantly increasing durability.

[0007] Corresponding composite materials are then usually applied to a carrier and can be clamped, glued or otherwise attached.

[0008] To ensure efficient production and good recyclability, many products require a reduction in the amount of different materials used. For example, adhesives contained in durable plastic products may lose their functionality and / or be detrimental to recycling.

[0009] Furthermore, reducing the use of materials can also result in benefits during the use of corresponding products. For example, it is known that volatile components in conventional adhesives used to bond plastic materials can escape over extended periods, which can be perceived, for example, as odor pollution. The handling of adhesives during production can also lead to certain contamination and / or increased safety requirements.

[0010] DE 10 2018 114 566 B3 describes that a spacer fabric intended as an interior trim part can be back-injected, whereby the back-injected plastic then forms a carrier.

[0011] DE 10 2019 129 947 A1 describes a spacer fabric comprising a first layer, a second layer, and spacer threads connecting the layers. Furthermore, a molded part intended, in particular, as interior trim for a motor vehicle is described, which is formed from the spacer fabric and an adjoining plastic substrate. It is essential that one layer of the spacer fabric contains polypropylene.

[0012] DE 42 14 389 A1 also describes a layered structure, particularly in the form of a vehicle interior trim component. The layered structure can comprise a spacer fabric as a pressure-resistant layer and be back-injected with another layer of plastic.

[0013] DE 20 2013 005 923 U1 and WO 2014 / 202768 A1 describe an interior trim element, for example, for a passenger compartment of a motor vehicle, which can have a foam or a spacer fabric as a cushioning layer. The cushioning layer can also be laminated with a thin film. Such a lamination on the back of the cushioning layer is particularly provided when, according to one variant, back-injection molding is provided.

[0014] It should be noted that during the formation of an injection-molded composite, molten plastic is typically supplied and / or compressed at high pressure. In principle, the skilled person can influence the viscosity and pressure to a certain extent to prevent excessive penetration of molten plastic into the spacer fabric if a separate film is not to be used as a barrier. However, this limits the skilled person's options for variation in injection molding to a certain extent.

[0015] The present invention is based on the object of increasing the variation options available to the skilled person when forming an injection-molded composite with a spacer fabric. The spacer fabric should exhibit good functional properties and good cushioning properties and be particularly suitable for flexible injection molding, while also avoiding the inclusion of additional materials in the form of a film or the like. Furthermore, an injection-molded composite and a method for producing an injection-molded composite are also to be specified.

[0016] The subject matter of the invention and the solution to the problem are a spacer fabric according to patent claim 1, an injection-molded composite according to patent claim 13 and a method for producing an injection-molded composite according to patent claim 16.

[0017] Starting from a generic spacer fabric according to the preamble of patent claim 1, the invention accordingly provides that the ratio of the area weight of the first knitted fabric layer to the second knitted fabric layer is at least 2:1 and that the threads of the second thread system do not form stitches and each extend as a partial weft over at least 4 stitch wales.

[0018] According to the invention, the first knitted fabric layer is heavier and therefore denser than the first knitted fabric layer. With regard to the basis weight, the threads or thread system that directly form the first knitted fabric layer and the second knitted fabric layer must be taken into account. The spacer threads connecting the two knitted fabric layers are of course also incorporated into the two knitted fabric layers, but are not taken into account when determining the basis weight. The basis weights can be very easily determined during production based on the thread consumption for the respective guide rails and / or calculated theoretically. Even in a sample of a spacer knitted fabric to be examined, the spacer threads can be cut to separate the two knitted fabric layers and the corresponding fragments can then be removed from the knitted fabric layers.Under this condition, an experimental determination of the basis weights is also easily possible.

[0019] According to the invention, it is further provided that the first knitted fabric layer is formed by at least a first thread system and a second thread system of different layup. Using a warp knitting machine or a Raschel machine, the different thread systems are preferably assigned to a corresponding layup bar. The movement of the corresponding layup bars and thus the formed layup are then abstractly described by corresponding layup patterns. Reference is also made to the referenced textbook "Wirkerei und Strickerei" (Weaving and Knitting), Markus Oliver Weber / Klaus-Peter Weber, 6th edition 2014 (ISBN 978-3-86641-299-6), pages 178 et seq. The terms "partial weft" (page 32), "twill" (page 134), and "even layup" (page 186) used below are also explained therein in the context of the present invention.

[0020] As a further aspect of the present invention, the threads of the second thread system do not form stitches and each extend as a partial weft over at least four wales. In terms of production, this corresponds to a weft placement under at least four needles.

[0021] The second thread system itself does not form stitches and, in a top view of the spacer fabric, runs diagonally back and forth in a zigzag pattern across at least four wales. This results in a relatively large surface coverage of the parallel threads, with the corresponding guide rail preferably being fully covered.

[0022] A simple geometric analysis reveals that the thread length used correlates directly with the surface coverage. Regarding dimensional stability and other mechanical properties, it is also crucial that the second thread system does not form loops, as this has a comparatively minor impact on the integration of the spacer threads, also known as pile threads.

[0023] Against this background, the invention is also based on the finding that, with regard to a uniform, usually curved course of the spacer threads between the knitted fabric layers and the pressure-elastic properties, it can be advantageous if the weight ratio of the stitch-forming threads in both knitted fabric layers does not differ too greatly.

[0024] According to a preferred embodiment of the invention, the partial weft of the second thread system extends over more than 5 wales. The partial weft can extend over a maximum of 8 or 7 wales. According to preliminary tests, it is particularly advantageous if the partial weft for the second thread system extends over 6 wales.

[0025] Within the scope of the invention, the first knitted fabric layer is achieved to be comparatively dense. It is understood that the spacer fabric is to be back-injected onto the first knitted fabric layer.

[0026] The comparatively dense design with the diagonally zigzag threads of the second thread system and the overall higher surface weight compared to the second knitted layer means that molten plastic is retained more effectively during injection molding and / or pressing.

[0027] The lamination of an additional barrier layer in the form of a film, fleece, or the like can be omitted. Instead, the molten plastic preferably borders directly on the first knitted fabric layer or even penetrates it to a certain extent. A certain degree of penetration can achieve a particularly reliable bond, while penetration or at least excessive penetration of the molten plastic through the first knitted fabric layer can be avoided. The intimate bond between the molten plastic and the first knitted fabric layer can, depending on the process, achieve a particularly high and long-term reliable bond adhesion. Additional materials such as adhesives or the like are not necessary, and the associated disadvantages can be avoided.

[0028] According to a preferred embodiment of the invention, the first knitted fabric layer also comprises a third thread system, wherein the threads of the third thread system also do not form stitches and each extend as a partial weft over at least four wales. In particular, the same lapping pattern as for the second thread system can be provided for the third thread system, whereby here, too, a full lapping of the corresponding lapping rail is particularly preferred.

[0029] The third thread system allows the first layer of the knitted fabric to be made even denser. It should be understood that the first layer of the knitted fabric, as a textile layer, is not completely dense in the sense of a closed surface, but this is not necessary for back-injection molding. Rather, the aim is to ensure that the remaining openings and pores during injection molding or back-injection molding are so small that molten plastic cannot penetrate them, even at low viscosity and high pressure.

[0030] The second and third thread systems can, in principle, be made with identical or different threads. Using the same thread, the second and third thread systems ultimately double the number of threads to achieve a particularly dense surface.

[0031] As already explained above, the optional third thread system can be designed to extend over 4 to 8, preferably 5 to 7, and for example, 6 wales. In principle, it can be advantageous for the second thread system and the third thread system to extend over the same number of wales, because then the individual threads can be arranged particularly evenly.

[0032] Against this background, it is particularly preferred if the second thread system and the third thread system are aligned. The individual threads can then lie flat next to each other without crossing, resulting in a particularly dense structure. It should be noted that certain gaps and spaces always remain at intersections due to the height difference, which is why a parallel and even arrangement of neighboring threads between the formed stitches can be particularly advantageous.

[0033] According to the previously presented embodiments with the second and third thread systems, a particularly dense structure can be achieved, which is thus particularly advantageous within the scope of the invention. Depending on the requirements, however, it may generally be sufficient for the first knitted fabric layer to use only the first thread system and the second thread system. Certain improvements can then be achieved, if necessary, by increasing the fineness. In principle, it is also possible to provide a double thread feed on a corresponding guide rail.

[0034] The threads of the first thread system form stitches and are thus responsible for the structural strength of the first layer of knitted fabric. It can also be advantageous if the stitch-forming threads of the first thread system each extend over a plurality of, for example, at least four wales.

[0035] The stitch-forming threads of the first thread system can also extend, for example, over 4 to 8, in particular 5 to 7 and preferably 6 wales.

[0036] With regard to the threads of the first thread system, it is also advantageous if they extend over the same number of wales as the threads of the second thread system and, if applicable, the third thread system. This also allows for an improved parallel alignment of all threads of the first thread system, thus achieving the densest possible structure essentially in one plane.

[0037] According to a preferred embodiment of the invention, a twill weave is provided for the threads of the first thread system. If the threads of the first thread system extend over 6 wales, i.e., if they have a backing length of 4 needles between the stitches during production, a twill velvet weave results according to a particularly preferred embodiment of the invention.

[0038] As already explained above, it is preferred if the threads of the first thread system, the threads of the second thread system and optionally the threads of the third thread system are arranged with a full thread feed or are processed in the laying rails with a full thread feed during production.

[0039] By using the three thread systems and skewing the threads of the first knitted fabric layer, the ratio of the basis weights of the first knitted fabric layer and the second knitted fabric layer of at least 2:1 provided for by the invention can be significantly exceeded. According to a preferred embodiment of the invention, the ratio of the basis weights of the first knitted fabric layer and the second knitted fabric layer is between 3:1 and 8:1, in particular between 4:1 and 7:1.

[0040] Multifilament yarns can be provided for the threads of the first thread system and / or the second thread system and / or the third thread system. Multifilament yarns consist of a large number of filaments, which also allows for a particularly uniform and dense structure. This is especially true if the threads of different thread systems run essentially flat, parallel to each other, at least in sections. For a multifilament yarn, for example, between 12 and 72, in particular 36, filaments can be provided.

[0041] In particular, texturing of the multifilament yarns can also be provided, making them even softer and more voluminous.

[0042] The fineness of the threads can, for example, be in a range between 33 dtex and 400 dtex. In particular, it can also be provided that the threads of the second thread system, which do not form stitches, have a finer fineness than the threads of the first thread system.

[0043] Even if, within the scope of the invention, threads made of conventional polymers are preferred for the two knitted fabric layers and the spacer threads, natural fibers or fibers made of natural raw materials can also be provided within the scope of the invention.

[0044] According to a particularly preferred embodiment of the invention, it is provided that the spacer fabric is formed entirely from a single polymer, so that only one polymer is used, which also makes recycling considerably easier.

[0045] For example, the entire spacer fabric can be made of a polyester, especially polyethylene terephthalate, allowing for single-material recycling. This is especially true when, during the formation of an injection-molded composite, a plastic body adjacent to the first layer of the fabric is also made of the same polymer.

[0046] The term "single-component" refers in particular to the common recycling classes, which differentiate between, for example, PET, PE, and PP. It is generally not critical if different types of PET are used within a specific polymer class, such as PET. However, it is also conceivable for the entire spacer fabric to be made from just one type of polymer.

[0047] The present invention is particularly concerned with the design of the first knitted fabric layer to enable particularly flexible injection molding without compromising the desired compressive elastic properties of the spacer fabric. Against this backdrop, the thickness of the spacer fabric and the design of the second knitted fabric layer can be varied very freely. The preferred designs given below are, of course, to be considered only as examples.

[0048] For example, the total thickness of the spacer fabric is between 2 mm and 10 mm, and especially between 3 mm and 7 mm. These thicknesses are particularly suitable for creating interior lining with a certain cushioning effect.

[0049] As further explained below, the spacer fabric in an injection-molded composite can either form a visible surface and thus an external surface of the injection-molded composite or a functional part produced with it, or alternatively, it can be combined with a decorative layer such as leather, synthetic leather, another textile, a film, or the like. Accordingly, the second layer of the fabric can also be designed differently.

[0050] The invention also relates to an injection-molded composite comprising the above-described spacer fabric on a plastic body, which is directly bonded to the first layer of the fabric. The bonded connection preferably occurs directly between the first layer of the fabric and the preferably injection-molded plastic body, without any additional material such as adhesive or the like.

[0051] In detail, various joining mechanisms are considered, which can also be combined with one another. With a material-to-material bond, the materials can adhere adhesively; during injection molding, the molten polymer forming the plastic body can also engage with the structure of the first knitted layer to a certain extent. However, a certain degree of mechanical interlocking also occurs, whereby individual threads or filaments can be enclosed by multifilament yarns, ultimately creating a bond that cannot be severed non-destructively. Depending on the process, a certain degree of fusion of the materials is also possible, especially if they consist of the same polymer or a same polymer class.

[0052] As already explained, the second knitted fabric layer can form a visible surface of the injection-molded composite. The second knitted fabric layer can, for example, have an attractive structure, and openings, a perforated pattern, or the like can also be provided.

[0053] According to one variant, a decorative layer can also be applied to the second knitted fabric layer, as described above. Such a decorative layer can be applied in various ways. Depending on the material, welding, gluing, sewing, or the like are possible.

[0054] Even if, depending on the application, undesirable adhesive is added as an additional material during bonding, the total amount of adhesive is reduced compared to a conventional interior trim part because the spacer fabric on the first fabric layer is directly bonded to the plastic body without any foreign material.

[0055] The invention also relates to a method for producing an injection-molded composite, wherein molten plastic is injected onto the first knitted fabric layer.

[0056] Within the scope of the invention, the method expressly encompasses different types of injection molding in the broad sense.

[0057] For example, the spacer fabric can be inserted into a mold, which is then closed at least along the first layer. The molten plastic can then be injected into the closed mold to form the injection-molded composite. Furthermore, a type of injection-compression molding is also possible. In this process, molten plastic is applied to the first layer of the fabric and only then pressed into the final shape. Depending on the type of finished product, the injection-molded composite can also be created by depositing a molten strand.

[0058] If a decorative layer is arranged on the second knitted fabric layer, this can be arranged on the spacer fabric either during the application of the molten plastic or subsequently, depending on the manufacturing process.

[0059] For example, it is also conceivable for a corresponding cover material for the decorative layer to be first loosely inserted into a mold and then bonded to the second knitted layer in an integrated process during the formation of the injection-molded composite. For this purpose, a decorative layer made of leather, synthetic leather, or the like can be coated with a hot-melt adhesive layer.

[0060] In contrast to the molding of the plastic body under high pressure, the amount of hot melt adhesive can be selected in such a way that it does not penetrate excessively into the spacer fabric even in the molten state and is essentially only intended for a connection with the second fabric layer.

[0061] The invention is explained below using exemplary figures. They show: Fig. 1 an injection-molded composite with an injection-molded plastic body and a spacer fabric, Fig. 2 a section of the injection molded composite according to the Fig. 1 in a detailed view, Fig. 3 an alternative design of the injection molded composite in a view corresponding to the Fig. 2, Fig. 4 a layout diagram of a spacer fabric according to the invention, Fig. 5 a layout diagram for an alternative embodiment of a spacer fabric according to the invention.

[0062] The Fig. 1 shows an injection-molded composite with a spacer fabric 1 and an injection-molded plastic body 2. The spacer fabric 1 has a first knitted fabric layer 3 adjacent to the plastic body 2, a second knitted fabric layer 4 forming the surface of the injection-molded composite, and spacer threads 5 connecting the knitted fabric layers 3, 4.

[0063] The Fig. Figure 2 shows a detailed view of a section of the injection-molded composite in a schematic representation. The first knitted fabric layer 3 is directly bonded to the plastic body, without any adhesive or other additional materials being provided in between. In particular, the material of the plastic body 2 can also penetrate the first knitted fabric layer 3 to a certain extent and even enclose individual threads or filaments of threads, thereby achieving a particularly tight connection.

[0064] However, the first knitted fabric layer 3, which is only shown in a highly schematic manner, is so dense that even in an injection molding process with a low viscosity of the molten plastic and a high pressure, no material can pass through the first knitted fabric layer 3.

[0065] In the formed injection-molded composite, the spacer threads 5 support the outer second knitted fabric layer 4 in a pressure-elastic manner against the first knitted fabric layer 3, wherein the useful side formed by the second knitted fabric layer in the embodiment according to the Fig. 1 and Fig. 2 forms a visible surface.

[0066] The one in the Fig. 1 and Fig. The injection-molded composite shown in Figure 2 can be intended, for example, as a trim part in a motor vehicle or the like. The plastic body 2 imparts the desired shape and stability to the injection-molded composite and can, in particular, also be designed for connection to a vehicle body or other sub-production. As described, the spacer fabric 1 is directly connected to the plastic body 2 without any additional material, which also determines the detailed shape.

[0067] The spacer fabric 1 is compression-elastic in a known manner, with the second fabric layer 4 forming the visible and generally also tactile surface of the injection-molded composite. The second fabric layer 4 can be freely formed according to functional and aesthetic requirements and, for example, can have a corresponding pattern and / or openings.

[0068] According to the invention, the ratio of the basis weight of the first knitted fabric layer 3 to the second knitted fabric layer 4 is at least 2:1, in particular between 3:1 and 8:1, and particularly preferably between 4:1 and 7:1. When determining the basis weight, the spacer threads 5 are not taken into account, even if they are incorporated to a certain extent into the knitted fabric layers 3, 4.

[0069] As explained below in connection with the Fig. 4 and Fig. 5, a particularly dense design of the spacer fabric 1 on the first knitted fabric layer 3 is achieved not only by the higher surface weight, but also by a particularly suitable laying of the corresponding threads.

[0070] The Fig. 3 shows starting from the Fig. 2 shows a variant in which a separate decorative layer 6 is arranged on the second knitted fabric layer 4. The decorative layer 6 can consist, for example, of leather, artificial leather, another textile, a film, or the like.

[0071] The Fig. 4 and Fig. 5 show concrete layouts for the spacer fabric 1. The first fabric layer 3 is formed by a first thread system F1, a second thread system F2, and a third thread system F3. A full thread insertion is provided for all three thread systems F1, F2, and F3 of the first fabric layer 3. Fig. 4 and Fig. 5 each show the knitting pattern for the guide rails used to manufacture the spacer fabric. For knitting-technical reasons, the first thread system F1 is assigned to the guide rail L3, the second thread system F2 to the first guide rail L1, and the third thread system F3 to the second guide rail L2.

[0072] Only the threads of the first thread system F1 form stitches in a twill velvet weave. In a twill weave, double stitches are formed, with the threads running diagonally between them in a velvet weave. In the illustrated embodiment, the threads of the first thread system each extend over 6 wales. Textured multifilament yarns with 36 filaments and a fineness of 76 dtex can be used as examples.

[0073] The threads of the second thread system F2 and the threads of the optionally provided third thread system F3 do not form stitches and are each provided as partial weft. In the specific embodiment, the partial weft for the second thread system F2 and the third thread system F3 also extends over 6 wales.

[0074] In addition, the threads of the thread systems F1, F2, and F3 forming the first knitted fabric layer 3 are equally spaced. Accordingly, all threads of the first knitted fabric layer 3 run largely parallel to each other and outside the formed stitches without further crossing. This results in a particularly dense arrangement essentially in one plane, whereby the penetration of molten plastic during an injection molding process can be particularly effectively prevented.

[0075] The core of the present invention relates in particular to the design of the first knitted fabric layer 3, so that the design of the spacer threads 5 and the second knitted fabric layer 4 can be varied widely. In the illustrated embodiment, the spacer threads 5 are formed by a fourth thread system F4 and a fifth thread system F5, wherein a full thread feed is provided for the spacer threads 5 on the corresponding guide rails. The spacer threads 5 are formed from monofilament yarn, which can, for example, have a fineness of 55 dtex. The fourth thread system F4 is assigned to the guide rail L4 and the fifth thread system F5 to the guide rail L5.

[0076] By using the two thread systems F4 and F5 for the spacer threads 5 when the corresponding laying rail is fully occupied, a comparatively high density of spacer threads 5 is achieved in the exemplary embodiment.

[0077] It should also be noted that during injection molding, the spacer fabric 1 itself can also be compressed and then recovers due to its elastic properties. Against this background, it is of course particularly important that no molten adhesive penetrates the first layer 3 of the knitted fabric, which could potentially impair the described elastic properties of the spacer fabric 1.

[0078] The Fig. 4 relates to a spacer fabric 1, in which the second fabric layer 4 is formed according to the Fig. 2 is provided as a visible surface. The second fabric layer 4 is formed by a sixth thread system F6 and a seventh thread system F7. The sixth thread system F6 is assigned to the sixth guide rail L6, and the seventh thread system F7 is assigned to the seventh guide rail L7.

[0079] The sixth thread system, F6, forms fringe stitches running along a wale during a full draw. A multifilament yarn with 36 filaments and a count of 167 dtex is suitable, for example. The seventh thread system, F7, creates a drawn-in weft with a 1 full / 1 empty weft configuration on the corresponding guide rail.

[0080] Accordingly, the seventh thread system F7 has a total of half the thread count of the sixth thread system F6. The 1 full / 1 empty weft pattern and the illustrated weft placement result in a draft of the fringe stitches formed by the sixth thread system L6, so that the corresponding wales appear wave-like in a top view along the production direction, and a certain perforated appearance is achieved simply by the drafting of the fringe stitches. Multifilament yarns with a count of 167 dtex can also be used for the seventh thread system F7 with the 1 full / 1 empty weft pattern.

[0081] According to a preferred embodiment of the invention, the entire spacer fabric is made of a single polymer, for example, polyethylene terephthalate (PET). The total thickness of the spacer fabric can, for example, be in a range between 2 mm and 10 mm, in particular between 3 mm and 7 mm. These ranges are particularly suitable for the formation of a pressure-elastic interior trim part.

[0082] The Fig. 5 relates to an alternative embodiment of a spacer fabric, in which the second fabric layer 4 is essentially designed differently, with a sixth thread system F6 and a seventh thread system F7. The sixth thread system F6 is assigned to the sixth guide rail L6, and the seventh thread system F7 is assigned to the seventh guide rail L7.

[0083] The sixth thread system F6 and the seventh thread system F7 each provide for full coverage of the guide rails. Both thread systems of the second fabric layer 4 form stitches, with a satin lay-up (sixth thread system F6) and a tricot lay-up (seventh thread system F7) being provided. A comparatively uniform surface is formed on which, in particular, as shown in the Fig. 3, a decorative layer 6 can be arranged. For the second knitted fabric layer 4, for example, textured multifilament yarns with 36 filaments and a fineness of 76 dtex can be used.

Claims

[1] Spacer fabric (1), in particular for forming an injection-molded composite, with a first knitted fabric layer (3) formed by at least one first thread system (F1) and a second thread system (F2) of different lay, a second knitted fabric layer (4) and spacer threads (5) connecting the knitted fabric layers (3, 4), wherein the first thread system (F1) has a stitch-forming lay, characterized by that the ratio of the area weights of the first knitted fabric layer (3) and the second knitted fabric layer (4) is at least 2:1 and that the threads of the second thread system (F2) do not form stitches and each extend as a partial weft over at least four stitch wales. [2] Spacer fabric (1) according to claim 1, characterized by that the first knitted fabric layer (3) comprises a third thread system (F3), wherein the threads of the third thread system (F3) also do not form stitches and each extend as a partial weft over at least four stitch wales. [3] Spacer fabric (1) according to claim 2, characterized by that the threads of the second thread system (F2) and the third thread system (F3) are arranged equally. [4] Spacer fabric (1) according to one of claims 1 to 3, characterized by that the threads of the first thread system (F1) each extend over at least four wales. [5] Spacer fabric (1) according to claim 4, characterized by that the threads of the first thread system (F1) and the second thread system (F2) are arranged equally. [6] Spacer fabric (1) according to one of claims 1 to 5, characterized by that the threads of the first thread system (F1) are arranged in a twill weave. [7] Spacer fabric (1) according to claim 6, characterized by that the threads of the first thread system (F1) are arranged in a twill velvet weave. [8] Spacer fabric (1) according to one of claims 1 to 7, characterized bythat the threads of the first thread system (F1), the threads of the second thread system (F2) and optionally the threads of the third thread system (F3) are arranged with a full thread retraction. [9] Spacer fabric (1) according to one of claims 1 to 8, characterized by that the ratio of the area weights of the first knitted layer (3) and the second knitted layer (4) is between 3:1 and 8:

1. [10] Spacer fabric (1) according to one of claims 1 to 9, characterized by that the threads of the second thread system (F2) are textured multifilament yarns. [11] Spacer fabric (1) according to one of claims 1 to 10, characterized by that the spacer fabric (1) is made of a single polymer, in particular polyethylene terephthalate. [12] Spacer fabric (1) according to one of claims 1 to 11, characterized by that the total thickness is in a range between 2 mm and 10 mm. [13] Injection-molded composite with a spacer fabric (1) according to one of claims 1 to 12 on an injection-molded plastic body (2), wherein the plastic body (2) is integrally connected to the first knitted fabric layer (3) and wherein the second knitted fabric layer (4) forms a useful side which is pressure-elastic compared to the first knitted fabric layer (3). [14] Injection-molded composite according to claim 13, wherein the second knitted fabric layer (4) forms a visible surface of the injection-molded composite. [15] Injection-molded composite according to claim 13, wherein a decorative layer is arranged on the second knitted fabric layer (4). [16] Method for producing an injection-molded composite, wherein a spacer fabric (1) according to one of claims 1 to 12 is provided and wherein molten plastic is injected and / or pressed onto the first fabric layer (3).

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