Fabric matrix made of reinforcing fibers

Abstract

The invention relates to a fabric matrix made of reinforcing fibres for producing composite material preforms, comprising a unidirectionally laid fabric made of at least one flat layer of multifilament reinforcing yarns arranged side by side and parallel to one another and bonded by transverse threads, wherein a nonwoven of thermoplastic polymer material is arranged on at least one multifilament reinforcing yarn flat layer, the nonwoven being bonded to the multifilament reinforcing yarn flat layer. The fabric matrix is characterized in that the transverse threads have a core / sheath structure having a first component constituting the sheath and a second component constituting the core, the first component having a lower melting point than the second component, the first component is a fusible thermoplastic polymer material and the multifilament reinforcing yarns arranged next to one another are joined together by melt bonding by means of the first component of the transverse threads.

Description

[0001] This application is a divisional application of a patent application with application number 201680056564.4, application date September 6, 2016, and invention name “Fabric matrix made of reinforced fibers”.

[0002] The invention relates to a textile matrix made of reinforcing fibers for producing a composite material preform, comprising a fiber composite or a unidirectional fabric consisting of at least one ply of multifilament reinforcing yarns arranged side by side and parallel to each other and bonded by transverse threads, wherein a nonwoven of a thermoplastic polymer material is arranged on at least one ply of multifilament reinforcing yarns and bonded to the ply of multifilament reinforcing yarns.

[0003] Made of reinforcing fibers or yarns, fiber composites in the form of unidirectional fabrics are long-known on the market. These fiber composites or unidirectional fabrics are widely used in the production of composite components with complex structures in some cases. In the intermediate step during the manufacture of this type of composite component, first a fiber preform is produced by a fiber composite or unidirectional fabric, and the preform is composed of a fabric intermediate in the form of a two-dimensional or three-dimensional structure made of reinforcing fibers, and its form can be close to the form of the final component. For embodiments of this type of fiber preforms that are basically only composed of reinforcing fibers and still do not have the matrix percentage required for the production of this part to a large extent, suitable matrix materials are incorporated into the fiber preforms by impregnation or injection or by applying vacuum in other steps. Subsequently, the matrix material is usually cured to form the final component under the temperature and pressure increased. In this case, the known method of impregnating or injecting the matrix material is a so-called liquid molding (LM) method, or a method related thereto, such as resin transfer molding (RTM), vacuum assisted resin transfer molding (VARTM), resin film impregnation (RFI), liquid resin impregnation (LRI) or resin impregnation flexible processing (RIFT).

[0004] To produce fiber preforms, fiber composites or unidirectional fabrics can be stacked on top of each other in several layers without a matrix material in a form or mold suitable for the contour of the component until the desired thickness is obtained. In other cases, several layers of fiber composites or fabrics can be first arranged on top of each other and combined together to form a dry multiaxial composite, for example, by sewing threads. The reinforcing fibers of each layer can be arranged parallel to each other or crosswise as an option. Typically, for multiaxial composites, angles of 0°, 90°, ±25°, ±30°, ±45° or ±60° are set, and the structure is selected so that a symmetrical structure relative to the 0° direction is produced. These multiaxial composites can then be easily further processed to produce preforms.

[0005] In many cases, the multiaxial composite has a thermoplastic polymer component with a relatively low melting point, for example in the form of sewing thread, or in the form of other polymer materials applied to the multifilament reinforcing yarn. During the production of the preform, the preform can be reinforced and thus stabilized by melting the polymer component and subsequently cooling it.

[0006] The use of composites or unidirectional fabrics made of multifilament reinforcing yarns arranged side by side and parallel to one another allows the production of fiber composite parts that can be selectively adapted to the loads acting on the part during application and therefore have high strength in each load direction. The use of multiaxial composites also enables low specific weights to be achieved by adapting the fiber density and fiber angles to the load directions present in the part.

[0007] Regarding the production of preforms, it is important that the raw materials used, such as composites made of multifilament reinforcement yarns arranged side by side and parallel to each other or unidirectional fabrics, and that the multiaxial composites made therefrom have sufficient stability and formability to ensure good handling and draping properties.

[0008] EP 1 352 118 A1 discloses, for example, a multiaxial composite, for which the reinforcing fiber layers are held together by fusible sewing threads, which ensure good formability of the multiaxial composite above the melting point of the sewing threads and stability of the shape during subsequent cooling. Sewing threads made of thermoplastic polymers such as polyamide or polyester are usually used, as disclosed, for example, in EP 1 057 605.

[0009] Preforms for composite preforms are described in US 2005 / 0164578, the preforms having at least one layer made of a reinforcing fiber fabric and wherein the fibers are incorporated in at least one layer, which stabilizes the preform when the fibers are subjected to elevated temperatures and dissolves in a matrix resin later introduced for the production of a composite component. WO 02 / 16481 also discloses a structure made of reinforcing fibers for use, for example, in a preform, wherein the structure comprises a flexible polymer element, which is introduced, for example, in the form of fibers, between the reinforcing fibers or as a sewing thread connecting the reinforcing fibers to one another. The flexible polymer element consists of a material soluble in the hardenable matrix material used.

[0010] According to DE 198 09 264 A1, bonded nonwovens made of thermoplastic polymers can be inserted between the reinforcing fiber layers of the fiber composite arrangement disclosed therein for a fiber preform, the layers being sewn together. Due to these melt-bonded nonwovens, the fiber composite arrangement can be formed in a simple manner into a three-dimensional structure when heated above the melting point of the polymer forming the nonwoven, which retains its shape after cooling, virtually without the need for restoring forces.

[0011] EP 1 473 132 has a multiaxial composite and a method for producing said multiaxial composite and a preform produced by the multiaxial composite as its theme.Multiaxial composite wherein has an intermediate layer made of thermoplastic fibers between the layers made of the reinforcing fibers laid by the uniaxial, wherein the intermediate layer can be a nonwoven made of bicomponent fibers or a mixed nonwoven made of different fibers mixed together.The polymer forming the intermediate layer should be compatible with the matrix resin injected into the preform later.Especially explained is that the intermediate layer should be permeable to the matrix resin during the resin impregnation and should during the resin impregnation and afterwards ensure the reinforcing fibers.When using epoxy resin, the nonwoven is made of polyamide fibers.The nonwoven can be connected with the layer made of the reinforcing fibers by means of knitting sutures or by means of melt bonding.

[0012] EP 1 705 269 discloses a thermoplastic fiber material made of polyhydroxy ether, which can be used for example for the multiaxial composite made of reinforcing fibers, for example as a nonwoven between the layers made of reinforcing fibers. When heat is applied, the polyhydroxy ether material becomes viscous and sticky, making it possible to realize that the reinforcing fibers are fixed with a specified geometric arrangement before being embedded in the matrix. The polyhydroxy ether fiber material is then fully dissolved in the matrix material at a temperature above its glass transition temperature.

[0013] Composites made of multiple reinforcing fiber layers are described in US2006 / 0252334, which contain, for example, nonwovens made of polymer fibers between the reinforcing layers to improve the impact strength of parts produced from these composites. Thus, these polymer fibers should be soluble in the matrix resin, according to the discussion of US2006 / 0252334, thereby giving the polymers forming these fibers a more uniform distribution in the resin matrix compared to fusible, insoluble thermoplastics.

[0014] Since the polymer fibers used for the composites of US 2006 / 0252334 and EP 1 705 269 are soluble in the matrix material and therefore dissolve during the infiltration of the composite with the matrix resin, the fixation of the reinforcement layer in this component production phase cannot be adequately ensured.

[0015] Also found in the patent documentation about the description of the substrate of the single-layer composite or single-layer unidirectional fabric form made of the multifilament reinforcing yarn arranged side by side and in parallel with each other that is suitable for producing fiber preform.For example, EP 1 408 152 describes the substrate of unidirectional fabric form, wherein the multifilament reinforcing yarn of unidirectional and parallel arrangement is woven together by the auxiliary silk thread of transverse operation with the multifilament reinforcing yarn.The auxiliary silk thread can be carbon fiber, glass fiber or organic fiber, for example aramid, polyamide, PBO, PVA or polyethylene fiber.The substrate described in EP 1 408 152 also can have bonding component, for example, is made of nylon or polyester or by hardenable resin such as epoxy, phenol or unsaturated polyester resin.In addition, the first and second resin components are combined with the multifilament yarn of unidirectional fabric.The second resin component has a higher melting point or flow starting temperature than the first resin component.

[0016] EP 2 233 625 discloses the matrix of the form of the single-layer composite made of the reinforcing fiber yarn arranged side by side with each other, and it has a curved profile, and wherein the reinforcing fiber yarn is kept together by the auxiliary silk thread that crosses with the reinforcing fiber yarn in the weft form.Nylon or glass filaments are preferably used as auxiliary silk threads, wherein particularly preferably glass filaments, because they do not shrink.Main component is that the resin material of thermoplastic polymer can be applied to the matrix point by point, in line form, in discontinuous form or in the form of nonwoven and bonded with the matrix with the stabilization of the curved form.

[0017] Although EP 2 233 625 already provides a matrix with cohesion and good stability even with curved contours, there is still a need for a matrix with improved stability while having high drapability and being suitable for automated production methods and automated processing into preforms.

[0018] The following object of the present invention is therefore to provide such a matrix. Another object is to provide a matrix based on reinforcing fibers which has good dimensional stability after being formed into a preform and good permeability during the infiltration of the matrix resin. At the same time, the components produced from these composites should have high strength properties, especially under pressure applications, and high impact strength.

[0019] This object is achieved with a textile matrix made of reinforcing fibers for producing a composite material preform, said textile matrix comprising a unidirectional composite consisting of at least one flat layer of multifilament reinforcing yarns arranged side by side and parallel to one another,

[0020] - wherein the multifilament reinforcing yarns arranged side by side are bound together by transverse threads, and - wherein the nonwoven of thermoplastic polymer material is arranged on at least one ply of multifilament reinforcing yarns and is bonded to the ply of multifilament reinforcing yarns,

[0021] - wherein the matrix is ​​characterized by the fact that the transverse threads have a core / sheath structure, wherein a first component forms the sheath and a second component forms the core, wherein the first component has a lower melting point than the second component, the first component is a fusible thermoplastic polymer material, and the multifilament reinforcing yarns arranged side by side are bonded together by melt bonding via the first component of the transverse threads.

[0022] In the context of the present invention, unidirectional composite should be understood as the arrangement of at least one multifilament reinforcing yarn flat layer arranged side by side and in parallel, wherein all reinforcing yarns are oriented in one direction.In unidirectional composite of the present invention, reinforcing yarn is combined together by transverse thread by fusion bonding, wherein transverse thread runs on or below the multifilament reinforcing yarn flat layer arranged side by side and in parallel and is laid on or below each layer and can be combined with the reinforcing yarn of layer.Multifilament reinforcing yarn arranged side by side and in parallel also can be woven or knitted together by transverse thread, can be connected with transverse thread by fusion bonding simultaneously.Therefore, the unidirectional composite of fabric substrate of the present invention also comprises the unidirectional fabric that all reinforcing yarns are also oriented in one direction.For these unidirectional fabrics, the reinforcing yarns arranged in parallel and forming layers are connected to each other by the chain of loosely combined thread in each case, and the chain extends laterally substantially with respect to reinforcing yarn.This type of unidirectional fabric is described in, for example, EP 0193 479 B1, EP 0 672776 or EP 2 233 625. Unidirectional composites preferably have a single flat layer of multifilament reinforcement yarns arranged side by side and parallel to each other.

[0023] The textile matrix of the invention has a high stability to the displacement of the reinforcing yarns in the longitudinal direction of the reinforcing yarns and in the transverse direction relative to the reinforcing yarns. This can be attributed on the one hand to the fact that the nonwoven of thermoplastic polymer material is bonded to the multifilament reinforcing yarn layer. On the other hand, the transverse filaments with a core / sheath structure produce a further stabilization, because the first component forming the sheath and consisting of a fusible thermoplastic polymer material having a lower melting point than the second component forming the core causes the multifilament reinforcing yarns arranged side by side to be bonded together by melt bonding.

[0024] At the same time, the core component with a higher melting point imparts sufficient lateral stability to the matrix with respect to possible shrinkage and with respect to possible elongation even at relatively high temperatures, for example during hardening of the matrix resin during production of composite parts from the textile matrix of the invention.

[0025] The textile substrate according to the invention is very suitable for the production of fiber preforms, wherein several textile substrate layers are superimposed and, for example, placed in a form or mold, depending on the strength requirements of the composite component to be finally produced. Due to the good drapability of the textile substrate according to the invention, fiber preforms with curved contours can also be produced by this method. The textile substrate layers placed on top of each other can then be connected together, i.e. fixed, by a brief increase in temperature and subsequent cooling, for example by means of sheath components of nonwovens or transverse threads, so that a stable and controllable fiber preform is obtained.

[0026] As already explained, the first component forming the sheath of the transverse threads has a lower melting point than the second component forming the core. The melting point of the first component of the transverse threads is preferably 70-150° C., more preferably 80-120° C. The first component can be a polymer or a polymer mixture whose melting point lies in this range. Particularly preferably, the first component consists of a polyamide homopolymer or a polyamide copolymer or a mixture of polyamide homopolymers and / or polyamide copolymers. Of these polymers, polyamide 6, polyamide 6,6, polyamide 6,12, polyamide 4,6, polyamide 11, polyamide 12 or polymers based on polyamide 6 / 12 are particularly suitable.

[0027] It is also preferred that the second component of the transverse threads has a melting point above 200° C. The second component is particularly preferably glass or polyester, since these materials have low shrinkage and low elongation at the temperatures prevailing during the production of the composite part.

[0028] In the fabric substrate of the present invention, reinforcing fibers or yarns commonly used for producing fiber-reinforced composite materials can be used as multifilament reinforcing yarns. Preferably, the multifilament reinforcing yarn is carbon fiber, glass fiber or aramid yarn, or highly stretched UHMW polyethylene yarn, particularly preferably carbon fiber yarn. In an advantageous embodiment, the multifilament reinforcing yarn in the fabric substrate has a mass per unit area of ​​50-500g / m2. Particularly preferably, a mass per unit area of ​​100-300g / m2. The multifilament reinforcing yarn is preferably composed of 500-50000 reinforcing fiber filaments. In order to achieve particularly good drapability and particularly uniform fabric substrate appearance, the multifilament reinforcing yarn is particularly preferably composed of 6000-24000 reinforcing fiber filaments.

[0029] The linear density of the transverse threads preferably corresponds to the number of reinforcing fiber filaments of the multifilament reinforcing yarn and therefore to the linear density of the multifilament reinforcing yarn. In unidirectional fabrics, not only do they usually have a multilayer structure consisting of a fabric matrix, but an excessively large linear density of transverse threads produces increased reinforcing yarn fluctuations. Therefore, the linear density of the transverse threads should preferably be no more than 1 / 5 of the density of the multifilament reinforcing yarn. The transverse threads preferably have a linear density of 20-400 dtex, particularly preferably 50-200 dtex.

[0030] In order to achieve as few fluctuations as possible, but at the same time to achieve sufficient stability of the textile matrix, it is also preferred that the number of transverse threads in the longitudinal direction of the multifilament reinforcing yarn is 0.3-6 threads / cm. The number is particularly preferably 0.6-2 threads / cm. The transverse threads can also run at right angles to the multifilament reinforcing yarn. However, any other possible angle between the transverse threads and the multifilament reinforcing yarn is also possible.

[0031] The nonwoven of fabric substrate can be the fabric made of unidirectional short-cut fibers or staple fibers or the random laying nonwoven made of continuous filaments, which must for example be combined by applying temperature and pressure, wherein the silk melts at the contact point, so forms a nonwoven. As explained, nonwoven affects the combination of multifilament reinforcement yarn on the one hand. Realize good drapability and / or the fiber preform produced by fabric substrate is well soaked by matrix resin simultaneously. Nonwoven for example can also be glass mat or carbon fiber mat, then combined with multifilament reinforcement yarn flat layer by adhesive.

[0032] Nonwoven is preferably made of thermoplastic polymer material. Such nonwoven is for example disclosed in DE 35 35272C2, EP 0 323 571A1, US2007 / 0202762 A1 or US2008 / 0289743A1. Properly select thermoplastic polymer material, nonwoven can serve as the reagent for improving impact strength, then during the production of composite material parts, no longer need to be used to improve the impact strength of other ways to add in the matrix material itself. Thus, nonwoven still has enough stability during the fiber preform produced by the fabric matrix is ​​soaked by the matrix material, but should preferably melt under subsequent extrusion and / or curing temperature. Therefore, the thermoplastic polymer material forming nonwoven has a melting point of 80-250 ℃. The nonwoven made of polyamide proves to be effective for the application of epoxy resin as matrix material.

[0033] In a preferred embodiment, the nonwoven comprises a first and a second polymer component whose melting point is below the melting and decomposition temperature of the second component of the transverse threads, wherein the second polymer component has a lower melting point than the first polymer component. The first polymer component is particularly preferably insoluble in epoxy resins, cyanate resins or benzoic acid ester resins. The first polymer component may be a component which is insoluble in the oxazine matrix resin or in a mixture of these matrix resins. It is particularly advantageous if the melting point of the first polymer component is at least as high as the solidification temperature of the matrix resin.

[0034] As long as they meet the above conditions, polymers that can usually be processed into thermoplastic fibers can be used as the first polymer component of the preferred nonwoven used, for example polyamide, polyimide, polyamide-imide, polyester, polybutadiene, polyurethane, polyurethane, polypropylene, polyetherimide, polysulfone, polyethersulfone, polyphenylenesulfone, polyphenylene sulfide, polyetherketone, polyetheretherketone, polyarylamide, polyketone, polyphthalamide, polyphenylene ether, polybutylene terephthalate or polyethylene terephthalate or copolymers or mixtures of these polymers. The first polymer component of the nonwoven is particularly preferably a polyamide homopolymer or a polyamide copolymer or a mixture of a polyamide homopolymer and / or a polyamide copolymer. In particular, the polyamide homopolymer or polyamide copolymer is polyamide 6, polyamide 6,6, polyamide 6,12, polyamide 4,6, polyamide 11, polyamide 12 or a copolymer based on polyamide 6 / 12. The first polymer component of the nonwoven preferably has a melting point of 180-250°C.

[0035] In an advantageous embodiment, the second polymer component of the nonwoven has a melting point of 80-140° C. The second polymer component of the nonwoven can consist of conventional polymers having a melting point in this range, for example polyamide homopolymers or copolymers with a low melting point and mixtures of these polymers, polyolefins, in particular polyethylene (e.g. PE-LLD, PE-HD), copolyesters, ethylene vinyl acetate, terpolymers, for example acrylonitrile-butadiene-styrene copolymers (ABS), or polyhydroxy ethers.

[0036] In a preferred embodiment, the second polymer component is thus soluble in epoxy resins, cyanate resins or benzoic acid ester resins. In this case, it is particularly advantageous if the second polymer component is a polymer which reacts with epoxy resins, cyanate resins or benzophenone resins during crosslinking of these matrix resins. The second polymer component is then particularly preferably a polymer which has already been completely dissolved in the resin system, in particular epoxy resins, cyanate resins or benzophenone resins, during the impregnation of the fiber preform made of the textile matrix according to the invention with these matrix resins, i.e. during the resin impregnation process. The first polymer component is insoluble in the matrix system and remains as a separate phase during and after the resin impregnation process and after the matrix resin has cured.

[0037] In a further preferred embodiment, the second polymer component is insoluble in epoxy resins, cyanate resins or benzoic acid ester resins. In some embodiments, the nonwoven fabric may be a polyamide homopolymer or copolymer with a low melting point or a mixture of these, or a polyolefin, in particular polyethylene (e.g. PE-LLD, PE-HD), a copolyester, ethylene vinyl acetate or a terpolymer, such as acrylonitrile-butadiene-styrene copolymer (ABS).

[0038] In nonwovens having a first and a second polymer component, it is particularly advantageous if the melting point of the first polymer component of the nonwoven is 180-250° C. and the melting point of the second polymer component of the nonwoven is 80-140° C.

[0039] The first polymer component particularly preferably melts above the curing temperature of the matrix resin used. In this way, the first polymer component is incorporated into the matrix material, but always forms a separate phase in the cured matrix resin. This separate phase formed by the first polymer component helps to limit crack propagation during curing and in subsequent components, thus decisively contributing to, for example, an increase in impact strength.

[0040] If the nonwoven comprises a first polymer component having a higher melting point and a second polymer component having a lower melting point, mobility of the matrix layers relative to each other can be achieved during the production of the fiber preform by heating to a temperature above the melting point of the second polymer component but below the melting point of the first polymer component. The molten second component of the nonwoven similarly acts as a lubricant so that the layer of reinforcing yarn can slide to the desired position in the preform during the forming process. During the cooling of the preform, the second polymer component then acts as a hot melt adhesive and fixes the reinforcing layer in its position.

[0041] During the subsequent impregnation of the fiber preform with the matrix resin, which is usually carried out at a temperature above the melting point of the second component but below the melting point of the first component, the higher melting point of the first polymer component of the nonwoven ensures good matrix resin permeability. If the second polymer component is soluble in the matrix resin, as in one of the above-mentioned embodiments, the component is then preferably completely dissolved in the matrix resin, and therefore loses its characteristic as a separated phase relative to the matrix resin. Therefore, the content of the second polymer component is then attributed to the matrix material, and the content of the matrix resin to be impregnated can be reduced by the content of the second polymer component. Therefore, the high fiber volume content of the reinforcing fiber can be set in the resulting parts, so that the mechanical strength properties can be maintained at a high level. In a particularly preferred embodiment, in the matrix resin, i.e., epoxy resin, cyanate resin or benzoic acid ester resin, the fiber preform is preferably soluble in the matrix resin. At the curing temperature of the oxazine resin, the second polymer component chemically reacts with the curing matrix resin via a cross-linking reaction, thereby becoming an integral part of the homogeneous matrix.

[0042] The second polymer component is insoluble in epoxy resin, cyanate resin or benzoic acid. In the case of being insoluble in the matrix resin of the oxazine or in a mixture of these matrix resins, the first polymer component, as described above, acts as a lubricant, allowing the mobility of the matrix layers relative to each other, allowing the reinforcing yarn layers to slide to the desired position during the molding into the preform, and acts as a hot melt adhesive to fix the reinforcing layers in their position when the preform cools. However, during the impregnation with the matrix resin and its subsequent solidification, it maintains its characteristics as a phase independent of the matrix resin, so that in this case, the second polymer component as well as the first polymer component reduces the propagation of cracks, thus contributing, for example, to an improvement in impact strength.

[0043] Under the situation that nonwoven has the first polymer component with higher melting point and the second polymer component with lower melting point, it can be made up of the mixture of the monocomponent fibers of each polymer component, that is, it can be a mixed nonwoven.But nonwoven also can be made up of bicomponent fibers, for example core / sheath fibers, wherein the core of fiber is made up of the first polymer component with higher melting point, and sheath is made up of the second polymer component with lower melting point.During the fabric substrate is processed into fiber preform with this mixed nonwoven or bicomponent nonwoven, it also requires for example the molding of fabric substrate, more than the melting point of the nonwoven component with lower melting point but at the temperature below the melting point of the nonwoven component with higher melting point, appropriately apply heat during molding to produce good formability, and after cooling, produce good stabilization and fixing of molding composite.Similar to the nonwoven made up of bicomponent fibers, nonwoven also can be made up of the random laying composite of the fiber made up of the first polymer component, wherein the second polymer component is for example applied on the fiber of the first polymer component by spraying or coating. The coating can be produced, for example, by impregnation with a dispersion or solution of the second polymer component, wherein after impregnation, the liquid portion of the dispersion or the solvent is removed. The nonwoven made of fibers made of the first polymer component can also contain the second polymer component in the form of fine particles embedded between the fibers of the first polymer component.

[0044] The nonwoven comprising the first and second polymer components is preferably a hybrid nonwoven, i.e. a nonwoven made from a mixture of monocomponent fibers with different melting points. As already described, the first polymer component with the higher melting point particularly preferably has a melting point of 180-250° C. At this temperature, the nonwoven portion consisting of the first polymer component melts only above the temperature which usually prevails during the injection of the matrix resin. Since the first polymer component is thus still not melted at the resin injection temperature, good dimensional stability of the textile substrate is ensured in this phase.

[0045] In view of the properties of the composite parts produced using the textile substrate of the present invention, in particular in view of their impact strength and their matrix content, it is advantageous that the nonwoven contains a content of 60-80% by weight of the first polymer component and a content of 20-40% by weight of the second polymer component. In general, the nonwoven preferably present in the textile substrate of the present invention has a mass per unit area of ​​5-25 g / m2, particularly preferably a mass per unit area of ​​5-15 g / m2.

[0046] In particular, if the nonwoven of the textile substrate contains only one polymer component with a relatively high melting point, i.e., for example, only one polymer component with a melting point in the range of 180-250° C., in a preferred embodiment, the textile substrate also contains an adhesive material whose main component is a thermoplastic polymer or a bisphenol A-based epoxy resin on at least one surface of the multifilament reinforcing yarn flat layer, which is solid at room temperature and is applied discontinuously to the multifilament reinforcing yarn flat layer and bonded to the multifilament reinforcing yarn. Discontinuous application should be understood here as an application in which the adhesive material is applied point by point, in the form of a line or in some other way on the surface without producing a closed layer of adhesive material. The adhesive material is preferably used in a concentration of 1-5% by weight of the mass per unit area of ​​the multifilament reinforcing yarn.

[0047] In a particularly preferred embodiment of the textile substrate, the binder material is based on a powder material and is applied point by point to the flat layer of multifilament reinforcing yarns. This can be achieved by spreading the powdered binder material on the surface of the multifilament reinforcing yarn layers arranged side by side and parallel to each other and fixing it on the surface by melting.

[0048] Polyvinyl acetate, polycarbonate, polyacetate, polyphenylene ether, polyphenylene sulfide, polyallylate, polyester, polyamide, polyamideimide, polyimide, polyetherimide, polysulfone, polyethersulfone, polyetheretherketone, polyaramid, polybenzimidazole, polyethylene, polypropylene or cellulose acetate can be preferably used as the thermoplastic polymer of the binder material.

[0049] The melting point of the binder material is preferably 80-120° C. Thus, the binder material can have purely the function of bonding the textile matrix layers laid on top of each other and fixing them relative to each other during the production of the fiber preform by heating to a temperature above the melting point of the binder material and subsequent cooling. In addition, the binder material can contribute to the stabilization of the fiber preform if, for example, deformations of the textile matrix layers occur during the shaping of the fiber preform. However, the binder material can also be ultimately selected such that it contributes to an improvement in the mechanical properties of the composite component made from the fiber preform, for example an improvement in the impact strength of the component. It is advantageous here that the binder material is a thermoplastic material with high toughness or a mixture of such a thermoplastic polymer with a bisphenol A-based epoxy resin that is solid at room temperature.

[0050] Due to its specific structure, the matrix according to the invention is characterized by good drapability and fixability of the matrix layer in the fiber preform, good permeability during impregnation with the matrix resin during the production of the component from the preform, and it can be used to produce components with high mechanical strength and high impact strength. Therefore, the present invention is also suitable for fiber preforms for the production of composite components comprising the textile matrix according to the invention.

[0051] The bonding of the multifilament reinforcing yarns with transverse threads and simultaneously with a nonwoven and possibly with an adhesive material in a glued form imparts a high level of dimensional stability to the textile substrate, since the glue produces an excellent fixation of the multifilament reinforcing yarns relative to one another. This allows the production of textile substrates in which the multifilament reinforcing yarns are used in a straight form arranged side by side and parallel to one another, but also in a textile substrate having a curvilinear form. Therefore, a preferred embodiment relates to a textile substrate in which at least one layer of multifilament reinforcing yarns arranged side by side and parallel to one another has a curvilinear profile, wherein the multifilament reinforcing yarns are arranged parallel to the circumferential direction of the curvilinear profile, each multifilament reinforcing yarn follows its own track along the circumferential direction of the curvilinear profile, and the tracks of each multifilament reinforcing yarn have a common center of curvature.

[0052] In this fabric matrix with a curved form or profile, the multifilament reinforcing yarn runs in parallel with the circumferential direction (0 ° direction) along the curved profile. Contrary to the composite in which the multifilament reinforcing yarns are arranged side by side and in parallel with each other and have a linear path, the multifilament reinforcing yarns in the fabric matrix with a curved form are also arranged side by side and in parallel with each other, but follow different curved tracks with a common center of curvature. Here, the transverse filaments also run in a direction that crosses the multifilament reinforcing yarns and is transverse to the multifilament reinforcing yarns. Due to the high dimensional stability and due to the design of the fabric matrix of the present invention, in particular due to the bicomponent core / sheath structure of the transverse filaments, during the subsequent processing steps for producing fiber preforms or composite material parts, the curved form is also maintained. Further stabilization of the fabric matrix is ​​achieved here, wherein the nonwoven of the thermoplastic polymer material comprises a first polymer component and a second polymer component with the above-mentioned properties.

Claims

1. A textile matrix made of reinforcing fibers for producing a composite material preform, comprising a unidirectional composite consisting of at least one ply of multifilament reinforcing yarns arranged side by side and parallel to one another, - wherein the multifilament reinforcing yarns arranged side by side are bound together by transverse threads, and - wherein a nonwoven of a thermoplastic polymer material is arranged on at least one ply of multifilament reinforcing yarns and bonded to the ply of multifilament reinforcing yarns, Features: - the transverse threads have a core / sheath structure, wherein a first component forms the sheath and a second component forms the core, wherein the first component has a lower melting point than the second component, the first component is a fusible thermoplastic polymer material, and the multifilament reinforcing yarns arranged side by side are bonded together by melt bonding via the first component of the transverse threads.

2. The textile substrate according to claim 1, characterized in that The first component of the transverse threads has a melting point of 70-150°C.

3. The textile substrate according to claim 2, characterized in that The first component of the transverse threads is a polyamide homopolymer or a polyamide copolymer or a mixture of a polyamide homopolymer and / or a polyamide copolymer.

4. Textile substrate according to one or more of claims 1 to 3, characterised in that The second component of the transverse threads has a melting point above 200°C.

5. The textile substrate according to claim 4, characterized in that The second component of the transverse threads is glass or polyester.

6. Textile substrate according to one or more of claims 1 to 5, characterised in that The transverse threads have a linear density of 20-400 dtex.

7. Textile substrate according to one or more of claims 1 to 7, characterised in that The nonwoven has a mass per unit area of ​​5-25 g / m2.

8. Textile substrate according to one or more of claims 1 to 7, characterised in that The nonwoven comprises a second component having a melting point below the melting point or decomposition point of the transverse threads and being insoluble in epoxy resin, cyanate resin or benzoic acid ester resin. The invention relates to a first polymer component in an oxazine base resin or a mixture of these base resins, and a second polymer component having a lower melting point than the first polymer component.

9. The textile substrate according to claim 8, characterized in that The first polymer component of the nonwoven has a melting point of 180-250°C and the second polymer component of the nonwoven has a melting point of 80-140°C.

10. Textile substrate according to claim 8 or 9, characterised in that The first polymer component of the nonwoven is a polyamide homopolymer or a polyamide copolymer or a mixture of a polyamide homopolymer and / or a polyamide copolymer.

11. Textile substrate according to one or more of claims 1 to 10, characterised in that Furthermore, it comprises an adhesive material whose main component is a thermoplastic polymer or a bisphenol A-based epoxy resin on at least one surface of the multifilament reinforcing yarn flat layer, which is solid at room temperature and is discontinuously applied to the multifilament reinforcing yarn flat layer and bonded to the multifilament reinforcing yarn.

12. The textile substrate according to claim 11, characterized in that The binder material has a melting point of 80-120°C.

13. Textile substrate according to one or more of claims 1 to 12, characterised in that The multifilament reinforcement yarns are carbon fiber, glass fiber or aramid yarns or highly drawn UHMW polyethylene yarns.

14. Textile substrate according to one or more of claims 1 to 13, characterised in that At least one layer of multifilament reinforcing yarns arranged side by side and parallel to each other has a curvilinear profile, wherein the multifilament reinforcing yarns are arranged parallel to the circumference of the curvilinear profile, each multifilament reinforcing yarn follows its own track along the circumference of the curvilinear profile, and the tracks of the multifilament reinforcing yarns have a common center of curvature.

15. A fiber preform for producing a composite material component, characterized in that It comprises a textile substrate according to one or more of claims 1 to 14.