Method for producing composite fiber materials with a particularly low degree of fiber warpage

Abstract

The invention relates to a method for producing fiber composite materials comprising a thermoplastic molding ccomposition A and at least one layer of reinforcing fibers B. The thermoplastic molding composition A is integrated into the at least one layer of reinforcing fibers B as a matrix, wherein the molding composition is integrated by moving the molding composition relative to the reinforcing fibers B within a consolidating step, in which the reinforcing fibers B remain immobile except for a one-dimensional production advancing movement, the thermoplastic molding composition A has at least one chemically reactive functionality, and the surface of the reinforcing fibers B is treated with a coating, the concentration of functional groups for the chemically reactive functionalities of the molding composition A being at least 0.3 mol.

Description

[0001] Process for the production of fiber composite materials with particularly low fiber distortion

[0002] The present invention relates to a process for producing fiber composite materials comprising a thermoplastic molding compound A and at least one layer of reinforcing fibers B, wherein the thermoplastic molding compound A is embedded as a matrix in the at least one layer of reinforcing fibers B, wherein the embedding takes place by a relative movement of the molding compound to the reinforcing fibers B within a consolidation step in which the reinforcing fibers B remain immobile except for a one-dimensional production feed and the thermoplastic molding compound A has at least one chemically reactive functionality and the surface of the reinforcing fibers B is treated with a size and the concentration of functional groups for the chemically reactive functionalities of the molding compound A is at least 0.3 mol%.

[0003] Fiber composites, also known as organosheets in their flat or planar form, comprise a thermoplastic matrix into which one or more fiber fabrics and / or one or more fiber layups are embedded. The fibers used to manufacture fiber composites are typically glass fibers, aramid fibers, or carbon fibers, which are incorporated into the thermoplastic matrix as continuous fibers or long fibers. The fiber length of the long fibers ranges from 1 to 50 mm, with fibers longer than 50 mm being referred to as continuous fibers. Fiber composites based on continuous fibers possess the highest stiffness and strength values ​​compared to fiber composites with shorter fibers.

[0004] Fiber-reinforced composites are typically made up of a multitude of reinforcing fibers embedded in a polymer matrix. Fiber-reinforced composites have a wide range of applications. Fiber-reinforced composites are primarily used in the automotive and aviation sectors. In these applications, the reinforcing fibers are intended to prevent tearing or other fragmentation of the polymer matrix, thus reducing the risk of accidents caused by component fragments. Many fiber-reinforced composites are capable of absorbing comparatively high forces under load before total failure occurs. At the same time, fiber-reinforced composites are distinguished from conventional, non-reinforced materials by their high strength and rigidity combined with low density and other advantageous properties, particularly good aging and corrosion resistance.A further advantage of fiber-reinforced composites is that their strength and stiffness can be adapted to the direction and type of load. The reinforcing fibers are primarily responsible for the strength and stiffness of a fiber-reinforced composite. Furthermore, the arrangement of the fibers within the fiber-reinforced composite determines its mechanical properties. The matrix, in contrast, usually serves primarily to transfer the forces to be absorbed into the individual reinforcing fibers and to maintain the spatial arrangement of the reinforcing fibers in the desired orientation. To ensure optimized force transmission, the reinforcing fibers should be arranged as straight as possible, i.e., without distortion, within the polymer matrix.Since both the reinforcing fibers and the matrix materials can be varied, the expert can consider numerous possible combinations of reinforcing fibers and matrix materials when manufacturing fiber composite materials.

[0005] One technical challenge is that, upon total failure, a fiber composite material can experience brittle fracture, meaning that fragments can be formed during failure and can move away from the fracture site at high speeds. Consequently, fiber composite-based products subjected to high or sudden loads can pose a significant accident risk if they tear or shatter.

[0006] Therefore, it is desirable to provide fiber composites with a wide load range where total failure is unlikely. Good optical properties and the ability to produce various elements with smooth surfaces using fiber composites are also desirable.

[0007] EP 1 923 420 B1 describes fiber composite materials with a matrix made of thermoplastic material in which layers of reinforcing fibers are embedded. A first group of reinforcing fibers is coupled to the matrix via a first fiber-matrix bond. A second group of reinforcing fibers is also coupled to the matrix via a second fiber-matrix bond. The second fiber-matrix bond is lower than the first fiber-matrix bond. By varying the fiber-matrix bonds, improved fracture behavior is achieved in the event of total failure. EP 1 923 420 B1 proposes thermosets such as polyester and the thermoplastics polyamide and polypropylene as matrix materials. Therefore, EP 1 923 420 B1 focuses on the bond between reinforcing fibers and the polymer matrix, the so-called fiber-matrix bond, in the production of fiber composite materials.

[0008] To optimize fiber-matrix adhesion and to compensate for a "low chemical similarity" between the reinforcing fiber surfaces and the surrounding polymer matrix, reinforcing fibers are regularly subjected to pretreatment. So-called sizing agents, preferably with the addition of adhesion promoters, have proven effective for this purpose. A sizing agent or a sizing / adhesion promoter is regularly applied to the reinforcing fiber during fiber production to improve its further processing, particularly by weaving, laying, or sewing. If the sizing agent is undesirable for subsequent processing of reinforcing fibers, it must first be removed in an additional process step, preferably by burning down.

[0009] However, it can also be advantageous to apply a bonding agent to the reinforcing fibers to be processed in an additional process step in addition to the size. Sizes and / or bonding agents form a layer on the surface of reinforcing fibers that can significantly influence the interaction of the reinforcing fibers with the environment. A wide variety of sizes and bonding agents are available today. Depending on the application, the matrix to be used, and the reinforcing fibers to be used, the skilled person can select a suitable size and bonding agent that is compatible with the matrix and the reinforcing fibers.

[0010] WO 2016 / 170131 A1 teaches the use of a fiber composite material W with a sandwich structure constructed from A) a thermoplastic layer w, containing as components a) a thermoplastic molding compound A as a matrix, b) a layer of reinforcing fibers B, and c) optionally additive C, wherein the reinforcing fiber layer B is embedded in the matrix of the thermoplastic molding compound A and the thermoplastic molding compound A has at least one chemically reactive functionality during the production of the material layer w, which in turn reacts with chemical groups on the surface of the reinforcing fibers B; and B) a further thermoplastic layer T and / or a foam layer S, wherein the further layer T and / or S is permanently bonded to the material layer w and thus leads to increased mechanical stability of molded parts produced therefrom.

[0011] DE 10 2016 102081 A1 relates to a method for producing a fiber-reinforced component, comprising the steps of: inserting fibers (16) into a mold (10) having a movable insert (12), pouring a matrix material (22) into the mold (10), and moving the insert (12) in a direction of movement (B) during injection of the matrix material (22). According to DE 10 2016 102081 A1, the fibers (16) are introduced relative to the insert (12) in a direction transverse to the direction of movement (B) prior to injection of the matrix material (22).

[0012] EP 3 286 258 B1 describes a process for producing fiber composites comprising a thermoplastic molding compound A and at least one layer of reinforcing fibers B, wherein the at least one layer of reinforcing fibers B is embedded in the matrix with the thermoplastic molding compound A, and wherein the thermoplastic molding compound A has at least one chemically reactive functionality, the surface of the reinforcing fibers B is treated with a silane size, and the concentration of functional groups for the chemically reactive functionality is at least 0.3 mol%. EP 3 286 258 B1 does not take into account the fiber distortion that occurs during the production of fiber composites! This is not prevented by the process described in EP 3 286 258 B1.

[0013] WO 2016 170104 A1 relates to the use of a thermoplastic fiber composite material comprising a) at least one thermoplastic molding compound A as matrix, b) at least one layer of reinforcing fibers B and c) optionally at least one additive C, wherein at least one layer of reinforcing fibers B is embedded in the matrix of the thermoplastic molding compound and the thermoplastic molding compound A has at least one chemically reactive functionality which reacts with chemical groups of the surface of component B during the production process of the fiber composite material for the production of white goods such as household appliances, thereby enabling lightweight products.

[0014] Reinforcing fibers, especially glass fibers, are often treated with sizing in the prior art to protect the reinforcing fibers from friction. For example, DE-A 2160778 describes glass fiber-reinforced styrene polymers based on sized reinforcing fibers. Mutual damage due to abrasion is to be prevented, and cross-fragmentation (fracture) should not occur during mutual mechanical action.

[0015] Sizing can also facilitate the cutting process of reinforcing fibers to achieve uniform staple lengths. Sizing can also prevent agglomeration of the reinforcing fibers. Sizing can improve the dispersibility of short fibers in water, making it possible to obtain uniform fabrics using the wet-laid process.

[0016] A sizing agent can also help improve the bond between glass fibers and the polymer matrix, in which the glass fibers act as reinforcing fibers. This principle is particularly applicable to glass fiber reinforced plastics (GRP).

[0017] In addition to the adhesion promoter mentioned above, the sizes to be used for glass fibers preferably contain a large number of other components, particularly preferably film formers, lubricants or wetting agents.

[0018] Film formers protect glass fibers or glass filaments from mutual friction and can also enhance their affinity to synthetic resins, thus promoting the strength and cohesion of a glass fiber-based fiber composite. Preferred film formers are starch derivatives, polymers and copolymers of vinyl acetate and acrylic esters, epoxy resin emulsions, polyurethane resins, and polyamides. Film formers are preferably used in a proportion of 0.5 to 12 wt.%, based on the total size.

[0019] Lubricants impart suppleness to glass fibers and glass fiber-based products, especially fabrics, and reduce friction between the glass fibers and each other. However, the use of lubricants often impairs the adhesion between glass fibers and synthetic resin. Greases, oils, or polyalkylene amines are preferred lubricants. These lubricants are preferably used in an amount ranging from 0.01 to 1 wt.%, based on the total size.

[0020] Wetting agents reduce surface tension and improve wetting of the glass fibers or glass filaments with the sizing agent. For aqueous sizing agents, polyfatty acid amides are preferred as wetting agents in an amount of 0.1 to 1.5 wt.%, based on the total sizing agent.

[0021] To improve the adhesion of polymers to the reinforcing fiber surfaces, organofunctional silanes are preferably used as adhesion promoters. Particularly preferred organofunctional silanes are aminopropyltriethoxysilane, methacryloxypropyltrimethoxysilane, or glycidyloxypropyltrimethoxysilane. These silanes, which are added to an aqueous sizing agent, are usually hydrolyzed to silanols. These silanols can then react with reactive reinforcing fiber surfaces, thus forming an adhesive layer, preferably with a thickness of approximately 3 nm.

[0022] When glass fibers are used as reinforcing fibers, low-molecular-weight functional agents from the matrix plastic can react with the silanol groups on the glass fiber surface. These low-molecular-weight agents then react further (particularly in epoxy resins), thereby ensuring a chemical bond between the glass fiber and the polymer matrix. However, such a process is time-consuming, taking approximately 30 minutes to over an hour for the polymers (particularly the aforementioned epoxy resins) to fully cure.

[0023] Functionalization of the silane sizing agent by reaction with polymers is also known. By functionalizing low-molecular-weight polycarbonate types, it is possible to effectively impregnate / saturate glass fiber fabrics or glass fiber scrims with polycarbonate, resulting in a "grafting" effect through the reaction of the functional groups in the polycarbonate with the glass fiber surface. However, such a process has the disadvantage that it cannot generally be applied to polycarbonate (PC). Only low-molecular-weight, i.e., low-viscosity polycarbonate can be used in this way, which, in turn, exhibits extremely poor usability and low resistance to stress-cracking agents, especially polar solvents.

[0024] Based on the prior art and thus the object of the present invention is to provide a process for producing fiber composite materials based on reinforcing fiber fabric, whereby the fiber composite material and molded articles to be produced therefrom receive improved properties, particularly with regard to its flexural strength, compared to the above-cited prior art, but based on the same matrix polymer.

[0025] The fiber composite material to be produced according to the invention and the molded body to be produced therefrom should be based on an easy-to-process, largely inert to conventional solvents, strong stress crack-resistant composite (quantifiable by its flexural strength) of reinforcing fiber fabric and matrix plastic and should have the lowest possible fiber warpage.

[0026] Fiber distortion in the sense of the present invention means any deviation from the ideal fabric shape defined in DIN ISO 9354. In an ideal fabric used as a fabric F according to the invention, the fibers are ideally parallel and stretched, with continuous fibers usually being used. Low fiber distortion, or distortion-free, in the sense of the present invention means that the deviation of the center line of a thread in relation to the thread length in the two-dimensional projection of the glass fiber fabric in the fabric plane is a maximum of 15%.

[0027] Glass fiber fabrics to be used as sheet materials F according to the invention can never be manufactured ideally from a physical or technical perspective. They are created by weaving continuous fibers, in particular by weaving rovings. The weaving of glass fibers is inevitably accompanied by undulation of the fibers. This undulation causes, in particular, a reduction in the compressive strength parallel to the fibers. Undulation is characterized by the fibers moving alternately upwards and downwards with respect to the plane of the sheet material F and are therefore not ideally parallel and stretched. If one considers the two-dimensional projection of an undulated fabric, the fibers are ideally stretched in the warp and weft directions of the fabric. Ideal parallelism is crucial for optimal power transmission of the fibers.If a thermoplastic polymer matrix is ​​embedded into the fabric F according to the invention, the ideal parallelism of the fibers can be maintained. The deviation from ideal parallelism is referred to as fiber distortion and is measured according to DIN EN ISO 13015 by optical inspection, e.g., using suitable gauges or camera-based systems. The position of the thread centerline in the main orientation is determined in relation to the thread length. A thread is defined as a bundle of fibers, also referred to as roving, yarn, fiber bundle, or filament bundle.

[0028] The invention relates to a process for producing a fiber composite material containing a thermoplastic molding compound A as polymer matrix M, reinforcing fibers B comprising the steps i) providing at least one sheet-like structure F in the form of a woven fabric made of reinforcing fibers B treated with silane sizing, ii) providing a thermoplastic molding compound A serving as matrix M which has at least 0.3 mol%, based on component A, of a chemically reactive functionality in the form of functional monomers, iii) optionally incorporating at least one additive C into the thermoplastic molding compound A, iv) introducing the thermoplastic molding compound A serving as matrix M into the at least one sheet-like structure F by embedding the thermoplastic molding compound A in the reinforcing fibers B by means of a relative movement,in which the reinforcing fibers B remain immobile except for a continuous or discontinuous one-dimensional production feed, and consolidating this composite of at least one sheet-like structure F and the matrix M, v) reaction of the chemically reactive functionalities of the thermoplastic molding compound A with the polar groups on the surface of the reinforcing fibers B treated with a silane size, vi) cooling the fiber composite material and optionally further process steps, wherein the chemically reactive functionality of the thermoplastic molding compound A is based on components selected from the group consisting of maleic anhydride, N-phenylmaleimide and glycidyl (meth)acrylate and steps iv) to vi) are carried out at a temperature of at least 150°C and steps v) to vi) are carried out by pressing at excess pressure.

[0029] Surprisingly, the process according to the invention produces a particularly distortion-free fiber composite material.

[0030] A special feature of the method according to the invention is the introduction of the matrix M into the at least one sheet-like structure F. The matrix M flows into the spaces between the reinforcing fibers B treated with a silane size. Excess size is thereby displaced from the rovings, yarns, fiber bundles or filament bundles of the reinforcing fibers B. The fiber composite material to be produced according to the invention is characterized by a complete coating of all individual fibers with the matrix M. This creates both optimized fiber-matrix adhesion and improved fixation of the reinforcing fibers in their spatial orientation, as a result of which a fiber composite material produced according to the invention has lower fiber distortion than a fiber composite material produced according to the prior art described above.

[0031] The introduction of the matrix M into the at least one sheet-like structure F in process step iv) is preferably carried out by melting the thermoplastic molding compound A and bringing it into contact with at least one sheet-like structure F made of reinforcing fibers B, as provided in process step i).

[0032] The melting of the thermoplastic molding compound A and the contacting of this melt with the reinforcing fibers B can be carried out in any suitable manner. During such impregnation, the matrix M based on the thermoplastic molding compound A is converted into a flowable state and the reinforcing fibers B are wetted, forming a boundary layer.

[0033] Process steps iii), iv), v) and vi) can also be carried out simultaneously. According to the invention, the at least one thermoplastic molding composition A contains at least 0.3 mol%, based on component A, of a chemically reactive functionality in the form of functional monomers. The at least one thermoplastic molding composition A preferably has at least one copolymer A-1 comprising monomers A1 that form covalent bonds with the polar or functional groups B1 of the reinforcing fibers B. Immediately upon bringing the at least one thermoplastic molding composition A into contact with the reinforcing fibers B, a chemical reaction occurs when process steps iv), v) and vi) are carried out simultaneously, in which the monomers A1 form a covalent bond with the surface of the reinforcing fibers B (usually via a bond to the functional groups B1).This is preferably an esterification, in particular an esterification of maleic anhydride monomers with silanol groups of a reinforcing fiber. Alternatively, the formation of a covalent bond can also be initiated in a separate step, in particular by increasing the temperature, using a radical initiator, or by photoinitiation, or a combination of these processes. This can be carried out at any suitable temperature.

[0034] Steps iv) to vi) are carried out at a temperature of at least 150°C, preferably at least 175°C, more preferably at least 200°C, and especially preferably in a range from 230°C to 300°C. It is preferable to ensure that pyrolysis does not occur and that the reactants or components used are not thermally decomposed.

[0035] According to a preferred embodiment, when carrying out steps iv) to vi), the residence time at temperatures of > 200°C is not more than 10 min, preferably not more than 5 min, particularly preferably not more than 2 min, especially preferably not more than 1 min. Often, 1 to 60 seconds are sufficient for process steps iv) to vi) and the thermal treatment carried out therein.

[0036] The process, in particular steps iv) to vi), can in principle be carried out at any desired pressure. Preferably, process steps v) and vi) are carried out at overpressure, which can improve the properties of the fiber composite material to be produced. Surprisingly, the surface appearance, in particular, could be improved in this way. Tests within the scope of the present invention showed that, particularly when process step vi) is not carried out at overpressure, the surface roughness and the proportion of air inclusions in the fiber composite material increased.

[0037] According to a preferred embodiment, process steps iv) to vi) are therefore carried out at a pressure in the range of 5 to 100 bar and a pressing time in the range of 1 to 60 s, particularly preferably at a pressure in the range of 10 to 30 bar and a pressing time in the range of 2 to 40 s.

[0038] Preferably, polypropylenes provided with at least one chemically reactive functionality (Al) are used as thermoplastic molding compound A in the matrix M. The use of amorphous thermoplastics, in particular styrene copolymers or polycarbonates, can significantly increase the surface quality of the fiber composite materials to be produced, since the lower shrinkage of the amorphous thermoplastics improves the surface topology due to the fiber-rich (crossing point in fabrics) and fiber-poor regions compared to semi-crystalline thermoplastics. If process step vi) is carried out according to the invention under overpressure, a comparable surface quality can surprisingly be achieved even with semi-crystalline thermoplastics!

[0039] In process step v) and in particular during consolidation in process step vi), the relative movement of the thermoplastic molding compound A in relation to the reinforcing fibers B displaces the air located between the reinforcing fibers, thereby reducing air inclusions in the fiber composite material to be produced and establishing a good bond between the thermoplastic molding compound A and the reinforcing fibers B. The preferred aim of the present invention is to obtain a (as largely as possible) pore-free material composite after impregnation and consolidation. Pore-free within the meaning of the present invention means that a fiber composite material contains less than 5 vol% air or vacuoles, which can be verified by means of optical measuring methods, X-ray images, density measurements, or ashing, in particular according to ASTM D2734-09.

[0040] Alternatively, the process steps can be performed in separate sequences. For example, layers of reinforcing fibers B with differently prepared reinforcing fibers B can first be prepared, with the reinforcing fibers B being impregnated with the matrix M of thermoplastic molding compound A. This can then result in impregnated layers of reinforcing fibers B with different fiber-matrix adhesion, which can be consolidated in a further step to form a composite material as a fiber composite. Before the layers of reinforcing fibers B are laminated with the matrix M of thermoplastic molding compound A, at least some of the reinforcing fibers B can be subjected to a pretreatment, during which the subsequent fiber-matrix adhesion is influenced.The pretreatment may preferably comprise a coating step, an etching step, a heat treatment step, or a mechanical surface treatment step. In particular, however, an already applied adhesion promoter may also be partially removed by heating a portion of the reinforcing fibers B.

[0041] The reinforcing fiber layers can be fully bonded together in the inventive manufacturing process known as lamination. Such fiber composite mats offer optimized strength and stiffness in the direction of the reinforcing fibers and can be further processed particularly advantageously.

[0042] Particularly preferred embodiments and starting materials of the process

[0043] Process step i)

[0044] Preferably, the at least one sheet F to be provided in process step i) is based on a woven fabric made of continuous fibers, including fibers that are the product of individual fiber twisting. According to "http: / / de.wikipedia.org / wiki / Faser-Kunststoff-Verbund," a distinction is made between chopped fibers, also referred to as short fibers, with a length in the range of 0.1 to 1 mm, long fibers with a length in the range of 1 to 50 mm, and continuous fibers with a length L > 50 mm.

[0045] According to the invention, the reinforcing fibers B processed into fabric are therefore preferably not chopped fibers; the fiber composite material to be produced according to the invention is therefore preferably not a short-fiber-reinforced fiber composite material. According to the invention, at least 50% of the reinforcing fibers B preferably have a length of at least 5 mm, particularly preferably at least 10 mm or more than 100 mm, whereby the length of the reinforcing fibers B also depends on the size of the molded part T to be produced from the fiber composite material F.

[0046] Fabrics to be used according to the invention in process step i) are preferably based on continuous fibers which, prior to processing into the fabric, are in the form of roving, yarn, fiber bundles, or filament bundles. Roving fabrics, yarn fabrics, or filament fabrics are therefore particularly preferably used. The fabrics to be used as sheet-like structures F in process step i) are preferably used in layers. In a preferred embodiment, the subject matter of the present invention therefore also encompasses a process for producing a fiber composite material with a layered structure and at least two layers of fabrics in the sheet-like structure F.

[0047] Preferably, the layers can be constructed in the same way or differently from one another. In a preferred embodiment, the invention therefore relates to a method for producing a fiber composite material with a layered structure and containing more than two, particularly preferably more than three, fabric layers. Preferably, all layers can be constructed in the same way, or some of the layers can be constructed differently, with "different" referring to the type of fabric, the weave, and the fabric materials. The weave of a fabric is determined by how weft threads alternate with warp threads, and the distances between them or between them.

[0048] A fiber composite material to be produced by the method according to the invention is traversed, preferably largely traversed, by at least one sheet-like structure F. Largely traversed here means that the at least one sheet-like structure F traverses more than 50%, preferably at least 70%, in particular at least 90%, of the length of the fiber composite material to be produced according to the invention. The length of the fiber composite material is the greatest extent in one of the three spatial directions. Particularly preferably, the at least one sheet-like structure F traverses more than 50%, very particularly preferably at least 70%, especially preferably at least 90%, of the area of ​​the fiber composite material to be produced according to the method according to the invention. The area is the area of ​​the greatest extent in two of the three spatial directions.

[0049] Preferably, flat or planar fiber composite materials are produced by the process according to the invention. In the case of flat or planar fiber composite materials, which are preferably produced according to the invention, the thread centerline of the individual threads of a sheet F or of the continuous fibers to be used for the fabric runs within a window with a height of < 15%, preferably a maximum of < 10%, in particular a maximum of < 5% along the length of the planar fiber composite material.

[0050] The flatness of a fiber composite material produced according to the invention is determined by its thickness. A fiber composite material is flat within the meaning of the present invention if the thickness of a 300 mm x 300 mm plate of the fiber composite material deviates from the mean plate thickness by no more than 10% at any point, with the plate thickness being measured at at least four points more than 100 mm apart using a thickness micrometer with a flat measuring head. For smaller plate dimensions, a fiber composite material is considered flat within the meaning of the present invention if the stated limits are scaled with the ratio of the smaller plate dimension to the 300 mm x 300 mm plate dimension and measured using the same measuring method.

[0051] Preferably, the at least one sheet-like structure F to be provided in process step i) is based on at least one fabric made of reinforcing fibers B treated with a silane size. Particularly preferably, glass fibers which have silane groups on the surface as chemically reactive functionality are used as reinforcing fibers B.

[0052] A particularly preferred subject matter of the invention in process step i) is the provision of at least one sheet-like structure F based on at least one fabric made of glass fibers which have silanol groups on the surface as chemically reactive functionality.

[0053] Preferably, based on 100 parts by mass of the fiber composite material to be produced by the process according to the invention, 5 to 80 parts by mass, particularly preferably 10 to 75 parts by mass, very particularly preferably 20 to 70 parts by mass, in particular 25 to 68 parts by mass of reinforcing fibers B are used.

[0054] The reinforcing fibers B are used as sheet materials F. The reinforcing fibers B can be any fiber whose surface has functional groups Bl that can form a covalent bond with the monomers Al of component A.

[0055] It is well known that the physicochemical properties of reinforcing fiber-based fiber composites, especially glass fiber-based fiber composites, and resins are influenced by the affinity, adhesion, and consequently the shear strength at the phase boundary between reinforcing fibers or glass fibers and the polymer matrix. The purpose of a size is to create a compatible bond between reinforcing fibers, especially glass fibers, and the surrounding resin, as well as to ensure the manufacturability and processability of a roving or roving.

[0056] Reinforcing fibers, especially glass fibers, are independent of their chemical

[0057] The composition is sensitive to kinking and abrasion. Therefore, during the fiber drawing process, precautions must be taken by applying a sizing agent to protect reinforcing fibers or glass fibers from the abrasive action of glass on glass and thus from the risk of mechanical damage.

[0058] The composition of a size influences not only the degree of cohesion, the hardness, the stiffness, the surface quality of reinforcing fiber or glass fiber based products, especially fabrics, but also technological processes such as the fiber drawing process (thread tension), winding (bobbin build-up) and the drying process (drying temperature, drying time) and in particular the further processability.

[0059] Sizes for reinforcing fibers, especially glass fibers, consist primarily of one or more film-forming agents, a lubricant, a wetting agent, and one or more coupling agents. A film-forming agent imparts the required integrity to the entire thread, especially a roving, protects the glass filaments from mutual friction, and can contribute to the affinity to the synthetic resin and thus to the strength of a fiber composite material to be produced according to the invention. By dissolving the film-forming layer in the matrix through possible chemical reactions with the polymer matrix, the adhesion and shear strength at the phase boundary between reinforcing fibers or glass fibers and synthetic resin can be increased, and consequently the strength and impact resistance of a composite material can be increased.

[0060] Starch derivatives, polymers and copolymers of vinyl acetate and acrylic esters, epoxy resin emulsions, epoxy polyester resins (see: EP-A-0 027 942), polyurethane resins, polyolefin resins or mixed emulsions of polyvinyl acetate and polystyrene are preferably used as film formers in amounts in the range of 0.1 to 12.0 parts by mass based on 100 parts by mass of the total size.

[0061] A lubricant in the size gives the product, in particular a textile glass roving to be treated with it, the necessary suppleness and reduces the mutual friction of the reinforcing fibers, preferably the glass fibers, both during production and during further processing, in particular by weaving. However, many lubricants impair the adhesion between the reinforcing fiber, in particular glass fiber, and the resin. Fats, oils, waxes or polyalkylene amines are used as lubricants in an amount in the range of 0.01 to 1.0 parts by mass, based on 100 parts by mass of the total size. A wetting agent as a size component reduces the surface tension of water and improves the wetting of reinforcing fibers, preferably glass fibers, with the size.As wetting agents, polyfatty acid amides in particular are used in the aqueous size, which is preferably in the form of an emulsion, in an amount in the range of 0.1 to 1.5 parts by mass, based on 100 parts by mass of the total size.

[0062] Most polymers used as a matrix have little or no affinity for glass and thus for the glass fibers preferably used as reinforcing fibers according to the invention. Adhesion promoters create a bridge between the glass fiber and the polymer, enabling complete force transfer in the fiber composite material or composite. Adhesion promoters increase the adhesion of polymers to the glass fiber surface. Organofunctional silanes, in particular γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycydyloxypropyltrimethoxysilane, are preferably used as adhesion promoters according to the invention. In the case of glass fibers, these adhesion promoters are preferably used in the sizing in amounts in the range of 0 to 1.0 parts by mass, based on 100 parts by mass of the total sizing.

[0063] Before the silanes used as adhesion promoters are added to the aqueous sizing, they are preferably hydrolyzed to silanols. Such a hydrolyzate solution has limited stability and is prone to condensation. Sizings containing adhesion promoters, so-called plastic sizings, may also contain other additives, preferably primers, antistatic agents, or emulsifiers, to achieve specific effects.

[0064] The auxiliary components to be used in sizing are generally known and are described, for example, in KL Löwenstein - The Manufacturing Technology of Continuous Glass Fibres, Elsevier Scientific Publishing Corp. Amsterdam - Oxford - New York, 1983.

[0065] According to the invention, the surface of the reinforcing fibers B to be used, in particular glass fibers, is treated with a silane size. This size serves as a lubricant, particularly during the weaving of the reinforcing fibers B or glass fibers, and can optionally be chemically removed after weaving. Particular preference is given to using glass fibers that have hydroxyl groups in the form of silanol groups as a chemically reactive functionality B1 on their surface as reinforcing fibers B.

[0066] In one embodiment, the surface of the reinforcing fibers B or glass fibers can have further functional groups B-II, in particular hydroxyl, ester, or amino groups. The reinforcing fibers B or glass fibers can be embedded in the fiber composite material as sheet-like structures F in any orientation and arrangement. In this case, they are not statistically evenly distributed in the fiber composite material to be produced according to the invention, but rather as sheet-like structures, i.e., in planes with a higher and planes with a lower proportion, i.e., as more or less separate layers. Preferably, a laminate-like or laminar structure of the fiber composite material to be produced according to the invention is assumed.

[0067] The adhesion promoter can be applied as part of the sizing during the production of the reinforcing fibers B, in particular glass fibers. However, an additional thermal desizing or other desizing process can also be provided, which destroys or removes an already applied sizing. The reinforcing fiber or glass fiber can then be coated with a finish containing the adhesion promoter and tailored to the respective matrix and the desired fiber-matrix adhesion. Alternatively, plastic layers can also be used. In one embodiment, adhesion promoters tailored to the matrix polymer can be used. These include crosslinkable polyetherurethane and / or polyesterurethane polymers that act as film formers, together with an aminosilane adhesion promoter.

[0068] Preferably, finished reinforcing fibers or glass fibers, especially in the form of fabrics, are equipped with modified silane sizes such as the finish FK 800; see R&G glass filament fabric canvas 25g / m 2 FK 800 glass fabric R & G twill 1901005, from R&G Faserverbundwerkstoffe GmbH in 711 11 Waldenbuch, Germany. These fabrics are very supple and hardly fray when cut.

[0069] According to the invention, the sheetlike structures F of the reinforcing fibers B are in the form of woven fabrics. The sheetlike laminates obtainable from the woven fabrics of reinforcing fibers B in the manner according to the invention preferably contain layered composites of sheetlike reinforcing fiber layers B and layers of the thermoplastic molding compound A, which wets and holds these sheetlike reinforcing fiber layers B together and serves as a matrix. According to a preferred embodiment, the matrix is ​​in turn embedded layerwise in the reinforcing fiber(s) B, thus forming the fiber composite material to be produced according to the invention.

[0070] Fabrics to be used as sheet materials F according to the invention are produced by weaving continuous fibers, in particular by weaving rovings. The weaving of (continuous) fibers is inevitably accompanied by an undulation of the fibers / reinforcing fibers. This undulation causes, in particular, a reduction in the fiber-parallel compressive strength. Undulation is characterized by the fibers / reinforcing fibers moving alternately upwards and downwards with respect to the plane of the sheet material F and are thus not ideally parallel and stretched. Looking at the two-dimensional projection of an undulated fabric, the fibers are ideally stretched in the warp and weft directions of the fabric. Ideal parallelism is crucial for optimal power transmission of the fibers.If the thermoplastic molding compound A, which serves as the matrix M, is embedded into the fabric F, the ideal parallelism of the fibers / reinforcing fibers can be maintained. The deviation from ideal parallelism is referred to as fiber distortion and is measured according to DIN EN ISO 13015 by optical inspection, particularly with the aid of suitable gauges or camera-based systems. The position of the thread centerline in the main orientation is determined in relation to the thread length. A thread is defined as a bundle of fibers, also referred to as roving, yarn, fiber bundle, or filament bundle.

[0071] According to a preferred embodiment, in the fiber composite material to be produced according to the invention, the thread center line deviates by a maximum of 15%, preferably a maximum of 10%, particularly preferably a maximum of 5% based on the length of the fiber composite material or of the molded part T produced therefrom from the ideal rectilinear, ie distortion-free, shape.

[0072] The process according to the invention preferably leads to a fiber composite material with a volume fraction of reinforcing fibers B in the form of sheetlike structures F defined according to DIN 1310 in the range from 25 to 65%, particularly preferably in the range from 30 to 55%.

[0073] The process according to the invention preferably leads to a fiber composite material with a volume fraction of air of a maximum of 5%, to be determined according to ASTM D2734-09, wherein the remaining volume is preferably completely filled by the molding compound A.

[0074] Process step ii)

[0075] Process step ii) involves providing a thermoplastic molding compound A serving as matrix M, which has at least 0.3 mol%, based on component A, of a chemically reactive functionality in the form of functional monomers. Having a chemically reactive functionality or being modified by a chemically reactive functionality means that the (co)polymer contains monomers (as building blocks) that lead to reactive chemical groups in the (co)polymer.

[0076] This chemically reactive functionality reacts with chemical groups on the surface of the reinforcing fibers B during the manufacturing process of the fiber composite material to be produced according to the invention. Preferably, a thermoplastic molding compound A based on a (co)polymer serving as a matrix is ​​used. Such a (co)polymer preferably comprises at least one functional monomer A1, the functionality of which reacts with chemical groups on the surface of the reinforcing fibers B during the manufacturing process of the fiber composite material. The (co)polymer comprising the monomer A1 is also referred to as polymer component (Aa) in the context of the present application.

[0077] Optionally, the thermoplastic molding compound A may additionally contain one or more (co)polymers, which are optionally also free of such chemically reactive functionality (therefore do not contain any functional monomer Al) and thus do not react with chemical groups on the surface of the reinforcing fibers B during the manufacturing process of the fiber composite material. Such a (co)polymer is also referred to as polymer component (Ab) in the context of the present application.

[0078] The thermoplastic molding compound A for the matrix M is preferably based on an amorphous or semi-crystalline plastic. The thermoplastic molding compound A to be used as the matrix M is particularly preferably used in the form of a semi-crystalline polymer. A solid that contains both crystalline and amorphous regions (domains) is referred to as semi-crystalline. When the melt of a polymer is cooled, the polymer chains move less and less and begin to arrange themselves in a regular manner, or crystallize. However, because they are entangled, this process cannot take place in the entire melt, but only in domains. In the rest of the melt, the chains solidify in a random manner (amorphous). The slower the melt is cooled, the more polymers crystallize. Polymers with short side chains crystallize better than those with long side chains. Crosslinked or branched polymers, on the other hand, are less likely to crystallize.According to DE 10 2011 084 519 A1, semi-crystalline polyamides have a melting enthalpy of more than 25 J / g, measured using the DSC method according to ISO 11357 during the second heating and integration of the melting peak, whereby this definition also applies to other semi-crystalline polymers. In process step ii), the matrix M is used in amounts such that a fiber composite material to be produced according to the invention is based on preferably 10 to 95 mass fractions, particularly preferably 20 to 50 mass fractions, very particularly preferably 23 to 40 mass fractions, and in particular 27 to 38 mass fractions of matrix M, based on 100 mass fractions of the fiber composite material.

[0079] The thermoplastic molding compound A to be provided as matrix M in process step ii) is preferably based on at least one polymer from the group consisting of polyolefins, polyamides, thermoplastic elastomers, polycarbonates, polybutadiene terephthalates, polylactides, polyphenylene sulfides and styrene copolymers.

[0080] Preferred styrene copolymers are styrene-acrylonitrile copolymers (SAN), a-methylstyrene-acrylonitrile copolymers (AMSAN), impact-modified styrene-acrylonitrile copolymers, acrylonitrile-butadiene-styrene copolymers (ABS), styrene-methyl methacrylate copolymers (SMMA), methacrylate-acrylonitrile-butadiene-styrene copolymers (MABS) or acrylic ester-styrene-acrylonitrile copolymers (ASA), wherein the styrene copolymers are modified with monomers (Al).

[0081] Blends of the above-mentioned copolymers with polycarbonate or with semi-crystalline polymers, in particular with polyamide, are also suitable, provided that the proportion of semi-crystalline mixed components in component A is less than 50 wt.%.

[0082] According to the invention, at least one of the polymer components in the thermoplastic molding composition A is preferably modified with monomer Al (polymer component (Aa). Any further polymer components, preferably styrene copolymers, in particular those as mentioned above, can optionally additionally be present in the thermoplastic molding composition A, which are optionally not modified with monomer Al (polymer component (Ab)).

[0083] SAN (MI) copolymers (modified by monomers A1) are particularly preferably used as a component (optionally also as the sole polymeric component) of the thermoplastic molding compound A.

[0084] According to the invention, at least one of the (co)polymer components of the thermoplastic molding compound A is a (co)polymer that has at least one chemically reactive functionality (polymer component (Aa)). Each of the copolymer components mentioned in the preceding paragraph regarding process step ii) can therefore, in addition to the explicitly mentioned monomers, also have a reactive functionality that can react with the surface of the reinforcing fibers B during the production of the fiber composite material. Thus, each of the aforementioned (co)polymers can also represent a polymer component (Aa).

[0085] Accordingly, the aforementioned polymer components, when used as polymer component (Aa), will generally also comprise at least one monomer A1, which imparts the chemically reactive functionality (hence the reaction with reinforcing fibers B). These can then preferably also be referred to as polystyrene-(A1) copolymer, styrene-acrylonitrile-(A1) copolymer, α-methylstyrene-acrylonitrile-(A1) copolymer, impact-modified acrylonitrile-styrene-(A1) copolymer, acrylonitrile-butadiene-styrene-(A1) copolymer (ABS-(A1)), and acrylonitrile-styrene-acrylic ester-(A1) copolymer (ASA-(A1)). Blends of the aforementioned copolymers with polycarbonate or polyamide are also possible.

[0086] Optionally, the above-mentioned polymer components, when used as polymer component (Aa), may also additionally comprise a second monomer (or even a third monomer) which has the chemically reactive functionality.

[0087] In particular, the above-mentioned polymer components (when used as polymer component (Aa)) can therefore also be referred to as polystyrene-maleic anhydride copolymer, styrene-acrylonitrile-maleic anhydride copolymer, a-methylstyrene-acrylonitrile-maleic anhydride copolymer, impact-modified acrylonitrile-styrene-maleic anhydride copolymer, acrylonitrile-butadiene-styrene-maleic anhydride copolymer (ABS-MA), or acrylonitrile-styrene-acrylic ester-maleic anhydride copolymer (ASA-MA) when maleic anhydride (MA) is used as monomer A1. Blends of the above-mentioned copolymers with polycarbonate or polyamide are also possible. The same applies to other monomers A1.

[0088] In one embodiment, in process step ii), one or more arbitrary further (co)polymers without such functionality (as polymer component (Ab)) can be used in addition to the one or more polymer components (Aa). Here, too, the above-mentioned (co)polymers polystyrene, styrene-acrylonitrile copolymers, α-methylstyrene-acrylonitrile copolymers, impact-modified acrylonitrile-styrene copolymers, acrylonitrile-butadiene-styrene copolymers (ABS) and acrylonitrile-styrene-acrylic ester copolymers (ASA), as well as blends of the above-mentioned (co)polymers with polycarbonate or polyamide, but then without the functionality (therefore without reactive monomer A1), can preferably be used. Polyolefins, very particularly preferably polypropylene (PP) or also high-density polyethylene (HDPE), are particularly preferably used as thermoplastic molding compound A.In such a case, the thermoplastic molding compound A preferably contains more than 50% polypropylene or a copolymer (A-1). According to one embodiment, such a thermoplastic molding compound A contains at least 90% copolymer A-1. In such a case, the thermoplastic molding compound A can also consist solely of copolymer A-1.

[0089] According to the invention, at least one of the components of the thermoplastic molding compound A preferably contains a (co)polymer having at least one chemically reactive functionality as described herein and referred to as polymer component (Aa). It is particularly preferred that at least one of the aforementioned polymer components comprises polypropylene and / or at least one copolymer A-1 (styrene copolymer, in particular SAN, SMMA, ABS, and ASA)) comprises at least one monomer A1.

[0090] In the particularly preferred case of using maleic anhydride (MA) as monomer A1, the polypropylene contains a polypropylene-maleic anhydride copolymer and the copolymer A-1 is particularly preferably styrene-acrylonitrile-maleic anhydride copolymer (SAN-MA), styrene-methyl methacrylate-maleic anhydride copolymer (SMM-MA), acrylonitrile-butadiene-styrene-maleic anhydride copolymer (ABS-MA) or acrylic ester-styrene-acrylonitrile-maleic anhydride copolymer (ASA-MA).

[0091] Optionally, in addition to the at least one polymer component (Aa), one or more other (co)polymers without such functionality can be used as the polymer component (Ab). Preferably, this can be polystyrene, SAN, SMMA, ABS, and / or ASA (each not comprising monomer A1).

[0092] In an alternative embodiment, the thermoplastic molding compound A is preferably an amorphous molding compound, wherein the amorphous state of the thermoplastic molding compound (thermoplastic) means that the macromolecules are arranged completely randomly without regular arrangement and orientation, ie without constant spacing.

[0093] In such a case, the entire thermoplastic molding compound A preferably exhibits amorphous, thermoplastic properties, is therefore meltable and (largely) non-crystalline. As a result, the shrinkage of the thermoplastic molding compound A, and therefore also of the entire fiber composite material, is comparatively low. Particularly smooth surfaces can be achieved in the molded parts T produced from the fiber composite materials produced according to the invention.

[0094] As a preferably amorphous molding compound, component A contains a semi-crystalline portion of less than 50 parts by mass, particularly preferably less than 40 parts by mass, based on 100 parts by mass of component A. Semi-crystalline thermoplastics form both chemically regular and geometric regions, i.e., there are regions in which crystallites form. Crystallites are parallel clusters of molecular segments or folds of molecular chains. Individual chain molecules can partially pass through either the crystalline or the amorphous region. They can sometimes even belong to multiple crystallites simultaneously.

[0095] The thermoplastic molding compound A can also be a blend of amorphous thermoplastic polymers and semi-crystalline polymers.

[0096] The thermoplastic molding compound A is preferably a blend of a styrene copolymer A-I, in particular a blend of SAN, with one or more polycarbonates and / or one or more semi-crystalline polymers, in particular polyamide, wherein the proportion of semi-crystalline mixed components in component A is less than 50 parts by mass, preferably less than 40 parts by mass, based on 100 parts by mass of the thermoplastic molding compound A.

[0097] According to the invention, the thermoplastic molding composition A preferably contains at least one copolymer A-1 which comprises monomers A1 which form covalent bonds with the functional groups B1 of the embedded reinforcing fibers B. The proportion of monomers A1 in the thermoplastic molding composition A can be selected variably. The higher the proportion of monomers A1 and the functional groups (B1), the stronger the bond between the thermoplastic molding composition A and the reinforcing fibers B can be. Monomers A1 can still be present in copolymer A-1 as monomers or can be integrated into the copolymer A-1. The monomers A1 are preferably integrated into the copolymer A-1.

[0098] According to a preferred embodiment, the copolymer A is constructed with a proportion of monomers A1 of at least 0.3 parts by mass, particularly preferably at least 0.5 parts by mass, very particularly preferably from 0.5 to 5 parts by mass, especially preferably at least 1 part by mass, especially very particularly preferably from 1 to 5 parts by mass, based on 100 parts by mass of copolymer A. The concentration of functional groups (chemically reactive functionality) is preferably at least 0.3 mol%, particularly preferably at least 0.5 mol%, very particularly preferably 1 mol%, especially preferably 1 to 5 mol%, based on 100 mol% of monomers which are used to produce the thermoplastic molding composition A.

[0099] According to a preferred embodiment, functional groups of the thermoplastic molding compound A are selected from the group of anhydride, ester, carboxy, amide, imide, acrylate, and glycidyl groups. Suitable monomers A1 that can form covalent bonds with the functional groups B1 of the reinforcing fibers B are all monomers that exhibit such properties. Preferred monomers A1 are those that can form covalent bonds by reaction with hydroxyl or amino groups.

[0100] Preferably, the monomers Al have:

[0101] (a) at least one functionality capable of forming covalent bonds with the functional groups Bl of the surface of the reinforcing fibers B, preferably by reaction with hydroxyl and / or amino groups; and

[0102] (b) at least one second functionality suitable for being incorporated into the copolymer A-1, preferably a double bond, particularly preferably a terminal double bond, which is preferably incorporated into the copolymer A-1 by means of radical polymerization.

[0103] Optionally, the copolymer A-1 or another (co)polymer contained in the thermoplastic molding compound A may contain one or more further monomers which are suitable for forming covalent or non-covalent bonds with the reinforcing fibers B.

[0104] According to a preferred embodiment, the monomers A1 are selected from the group consisting of maleic anhydride (MA), N-phenylmaleimide (PM), tert-butyl (meth)acrylate, and glycidyl (meth)acrylate (GM). According to a particularly preferred embodiment, the monomers A1 are selected from the group consisting of maleic anhydride (MA), N-phenylmaleimide (PM), and glycidyl (meth)acrylate (GM). Two of these monomers A1 can also be present in the copolymer A-1.

[0105] The copolymer A1 of the thermoplastic molding compound A can optionally contain further functional monomers A-II. Preferred copolymers A-1 are styrene / maleic anhydride, styrene / acrylonitrile / maleic anhydride, styrene / glycidyl methacrylate, styrene / N-phenylmaleimide, styrene / acrylonitrile / N-phenylmaleimide, methyl methacrylate / N-phenylmaleimide, methyl methacrylate / maleic anhydride, methyl methacrylate / maleic anhydride / N-phenylmaleimide, acrylonitrile / styrene / tert-butyl (meth)acrylate, acrylonitrile / butadiene / styrene / tert-butyl (meth)acrylate, and acrylonitrile / butyl acrylate / styrene / tert-butyl (meth)acrylate. Particularly preferred copolymers A1 are styrene / maleic anhydride, styrene / acrylonitrile / maleic anhydride, styrene / glycidyl methacrylate, styrene / N-phenylmaleimide, styrene / acrylonitrile / N-phenylmaleimide, methyl methacrylate / N-phenylmaleimide and methyl methacrylate / maleic anhydride / N-phenylmaleimide.

[0106] The preferred subject of the process according to the invention is a thermoplastic molding compound A made of polystyrene, in particular crystal-clear polystyrene (PS) or impact-resistant polystyrene or high-impact polystyrene (HIPS). Preferably, (partially) translucent or transparent fiber composite materials are produced using crystal-clear polystyrene.

[0107] In a particularly preferred embodiment, the polymer component (Aa) of the thermoplastic molding compound A to be used according to the invention is based on a polypropylene. In this case, the polypropylene additionally comprises a monomer A1, which reacts with the surface of the reinforcing fibers B during the manufacturing process.

[0108] The feature "modified by a chemically reactive functionality" or "having a chemically reactive functionality" means, according to the invention, in particular the incorporation of maleic anhydride monomers into the polymer chain of the (co)polymer to be used according to the invention.

[0109] Very particular preference is given to a process in which the chemically reactive functionality of the thermoplastic molding compound A is based on components selected from the group consisting of maleic anhydride, N-phenylmaleimide, tert-butyl (meth)acrylate and glycidyl (meth)acrylate, in particular selected from the group consisting of maleic anhydride, N-phenylmaleimide and glycidyl (meth)acrylate.

[0110] A modified polypropylene particularly preferably used as thermoplastic molding compound A according to the invention is produced from, based on 100 parts by mass of the modified polypropylene, 90 to 99.7 parts by mass of unmodified polypropylene, preferably 95 to 99 parts by mass of unmodified polypropylene, and 0.3 to 10 parts by mass, preferably 1 to 5 parts by mass, of maleic anhydride. The content of maleic anhydride in component A is particularly preferably in the range of 0.1 to 6 parts by mass, very particularly preferably in the range of 1 to 5 parts by mass, in particular in the range of 3 to 4 parts by mass, based on 100 parts by mass of modified polypropylene.

[0111] Mixtures of styrene-acrylonitrile copolymer with α-methyl-styrene-acrylonitrile copolymer are also suitable. An acrylonitrile-butadiene-styrene copolymer, which is preferably used as thermoplastic molding compound A according to the invention, is prepared by known methods from styrene, acrylonitrile, butadiene, and a functional further monomer A1, in particular methyl methacrylate.

[0112] According to the invention, at least one of the (co)polymer components of the thermoplastic molding compound A is preferably a (co)polymer that has at least one chemically reactive functionality as described (polymer component (Aa)). This can also be a polymer component as described above that contains at least one functional monomer A1 in the molding compound mentioned. Optionally, one or more other (co)polymers without such functionality can be used (as polymer component (Ab)).

[0113] In a further preferred embodiment, the matrix M can consist of at least two different thermoplastic molding compounds A. These different types of molding compounds can preferably be characterized by a different melt flow index (MFI) and / or contain other comonomers or additives.

[0114] According to the invention, the term molecular weight (Mw) can be understood in the broadest sense as the mass of a molecule or the area of ​​a molecule, in particular a polymer strand, a block polymer, or a small molecule, which can be expressed in g / mol (Da) and kg / mol (kDa). Preferably, the molecular weight (Mw) is the weight average, which can be determined using methods known in the art.

[0115] The thermoplastic molding compositions A to be used in process step ii) according to the invention preferably have a molecular weight Mw in the range from 10,000 to 800,000 g / mol, particularly preferably in the range from 20,000 to 600,000 g / mol, where Mw can be determined by light scattering in tetrahydrofuran (GPC with UV detector). The molecular weight Mw of the thermoplastic molding compositions A can vary within a range of + / - 20%. See: A. Müller, Polymer Characterization, Hanser Verlag 1996. Preferably, the thermoplastic molding compound A contains a polypropylene modified by a chemically reactive functionality, which, apart from the addition of the monomers A1, is essentially composed of the same monomers as the "normal polypropylene", whereby the monomer content deviates by + / - 5%, the molecular weight by + / - 20% and the melt flow index determined at a temperature of 230°C and a load of 2.16 kg according to ISO 1133 by + / - 20%.According to the invention, ISO 1133 is preferably understood to mean DIN EN ISO 1133-1:2012-03.

[0116] According to a preferred embodiment, the melt flow rate (Melt Volume Rate, MVR) measured according to ISO 1133 of the thermoplastic polymer composition A to be used as polymer matrix is ​​in the range from 0.1 to 400 cm 3 / 10min, particularly preferably in the range of 0.5 to 200 cm 3 / 10min, particularly preferably in the range of 1 to 150 cm 3 / 10 min at 230°C / 2.16kg.

[0117] According to a particularly preferred embodiment, the melt flow rate (Melt Volume Rate, MVR) measured according to ISO 1133 of the thermoplastic polymer composition A to be used as the polymer matrix is ​​in the range from 50 to 200 cm 3 / 10min, particularly preferably in the range of 70 to 150 cm 3 / 10min, particularly preferably in the range of 85 to 125 cm 3 / 10 min at 230°C / 2.16kg.

[0118] According to the invention, the process is particularly preferred if the thermoplastic molding composition additionally contains 0.1 to 6 parts by mass of maleic anhydride, based on 100 parts by mass of polypropylene. The mass fraction of maleic anhydride, based on 100 parts by mass of polypropylene, is very particularly preferably in the range of 0.2 to 5 parts by mass, particularly preferably in the range of 1 to 4 parts by mass, especially particularly preferably in the range of 3 to 4 parts by mass.

[0119] Process step iii)

[0120] Process step iii) relates to the optional incorporation of at least one additive C into the thermoplastic molding compound A serving as matrix M. A matrix M to be used according to the invention preferably contains 0.01 to 40 parts by mass of at least one additive C, more preferably 0.01 to 30 parts by mass, very preferably 0.01 to 25 parts by mass, especially preferably 1 to 20 parts by mass, per 100 parts by mass of the thermoplastic molding compound A, wherein the additive C is different from the base polymer of the thermoplastic molding compound A and from the reinforcing fibers B. Particulate mineral fillers, processing aids, stabilizers, antioxidants, agents against thermal decomposition, agents against decomposition by ultraviolet light, lubricants and mold release agents, flame retardants, dyes, pigments or plasticizers are preferably used as additive C.According to the present invention, two or more of these additives may also preferably be used.

[0121] Preferred particulate mineral fillers are selected from the group consisting of amorphous silica, carbonates, especially magnesium carbonate, calcium carbonate (chalk), powdered quartz, mica, silicates, especially clays, muscovite, biotite, suzoite, tin maletite, talc, chlorite, phlogopite, feldspar, and calcium silicates, especially wollastonite or kaolin. Kaolin is a particularly preferred mineral filler.

[0122] Preferred UV stabilizers are selected from the group of substituted resorcinols, salicylates, benzotriazoles and benzophenones.

[0123] Preferred oxidation inhibitors, also known as heat stabilizers, are selected from the group of sterically hindered phenols, hydroquinones, secondary aromatic amines, optionally in combination with phosphorus-containing acids or their salts, and mixtures of these compounds.

[0124] Preferred lubricants and mold-release agents are selected from the group consisting of stearic acid, stearyl alcohol, alkyl stearates, stearic acid amides, especially Irganox®, and esters of pentaerythritol with long-chain fatty acids. The calcium, zinc, or aluminum salts of stearic acid, as well as dialkyl ketones, especially distearyl ketone, can be used. Ethylene oxide-propylene oxide copolymers can also be used as lubricants and mold-release agents. Natural and synthetic waxes can also be used. Examples include polypropylene waxes, polyethylene waxes, polyamide waxes, grafted polyolefin waxes, HDPE waxes, PTFE waxes, EBS waxes, montan wax, carnauba waxes, and beeswaxes.

[0125] Flame retardants can be both halogen-containing and halogen-free compounds. Suitable halogen compounds, with brominated compounds being preferable to chlorinated ones, remain stable during the production and processing of the molding composition according to the invention, so that no corrosive gases are released and the effectiveness is not impaired. However, halogen-free compounds are preferably used as flame retardants, particularly preferably phosphorus compounds, in particular phosphine oxides and derivatives of phosphorus acids and salts of acids and acid derivatives of phosphorus. Particularly preferably, phosphorus compounds contain ester, alkyl, cycloalkyl, and / or aryl groups. Also suitable are oligomeric phosphorus compounds with a molecular weight of less than 2000 g / mol, as described, for example, in EP-A 0 363 608.

[0126] Pigments and dyes used as additives are generally known; see, for example, R. Gächter and H. Müller, Taschenbuch der Kunststoffadditive (Handbook of Plastics Additives), Carl Hanser Verlag, 1983, pp. 494 to 510. Preferred pigments are white pigments from the group consisting of zinc oxide, zinc sulfide, lead white, lithopone, antimony white, and titanium dioxide. Of the two most common crystal modifications of titanium dioxide (rutile and anatase types), the rutile form is particularly used to whiten the thermoplastic molding compounds used according to the invention.

[0127] Black color pigments that can also be used as additives according to the invention are iron oxide black (FesO^), spinel black (Cu(Cr,Fe)2O4), manganese black (= mixture of manganese dioxide, silicon oxide and iron oxide), cobalt black and antimony black and, particularly preferably, carbon black, which is usually used in the form of furnace or gas black (see G. Benzing, Pigmente für Anstrichmittel, Expert-Verlag (1988), p. 78ff). Of course, inorganic colored pigments such as chromium oxide green or organic colored pigments, in particular azo pigments and phthalocyanines, can be used according to the invention to achieve certain color shades. Such pigments are generally commercially available. Furthermore, it can be advantageous to use the aforementioned pigments or dyes in mixtures, in particular carbon black with copper phthalocyanines, which generally facilitates color dispersion in the thermoplastics.

[0128] Preferably, at least one additive C is incorporated into the thermoplastic molding compound A by compounding. Compounding, in turn, is preferably carried out in extruders, in particular in co-rotating twin-screw extruders, counter-rotating twin-screw extruders, planetary roller extruders, or in a co-kneader. Compounding comprises the process operations of conveying, melting, dispersing, venting, pressure buildup, and extrusion (ejection).

[0129] Procedural steps iv) to vi)

[0130] After the optional incorporation of at least one additive C into the thermoplastic molding compound A serving as matrix M, the same is introduced into the at least one sheet-like structure F provided in process step iv). In process step v), the chemically reactive functionalities of the thermoplastic molding compound A react with the polar groups on the surface of the reinforcing fibers B treated with a silane size, before the fiber composite material cools in process step vi) and, if necessary, further process steps follow.

[0131] The process according to the invention, in particular process steps iv) and v) or optionally also process step vi), are preferably carried out on a double-belt press, an interval-heating press, or a static press. A double-belt press, in particular, is capable of quasi-continuously producing a fiber composite from powder-based or film-based thermoplastic molding compound by converting it into a melt.

[0132] The introduction of the thermoplastic molding compound A serving as matrix M into the at least one sheet-like structure F is carried out by embedding the thermoplastic molding compound A into the reinforcing fibers B by means of a relative movement, during which the reinforcing fibers B remain immobile except for a one-dimensional production feed, and subsequently consolidating this composite of at least one sheet-like structure F and the matrix M.

[0133] Due to the relative movement of the thermoplastic molding compound A in relation to the reinforcing fibers B, the air located between the reinforcing fibers F is displaced. As a result, air inclusions in the fiber composite material are reduced and a good bond between the thermoplastic molding compound A and the reinforcing fibers B is prevented, especially when the molding compound A is embedded in layers. According to the invention, it is preferred to obtain a (as largely as possible) pore-free material composite after impregnation and consolidation.

[0134] The relative movement of the thermoplastic molding compound A in relation to the reinforcing fibers B is achieved by fixing the reinforcing fibers B in the direction of the relative movement. This fixation is created by holding the reinforcing fibers B in front of and behind the area in which the movement of the thermoplastic molding compound A is generated by a surface pressure > 10 bar at a temperature at least 10°C above the crystallite melting temperature or glass transition temperature in the case of amorphous thermoplastics, by means of mechanical clamping, winding or with the aid of fastening elements, and this holding is kept under constant tension by applying opposing forces. The reinforcing fibers B are fixed in their position in such a way that the tension in the longitudinal direction prevents movement in all spatial directions.Once the reinforcing fibers are secured in this way and the thermoplastic molding compound is exposed to the temperature and pressure described above for at least 1 second, the thermoplastic molding compound is moved into the spaces between the reinforcing fibers. After the thermoplastic molding compound has completed its movement, the reinforcing fibers are removed from the pressure and temperature area.

[0135] The reinforcing fiber remains immobile except for a continuous or discontinuous one-dimensional production feed. According to the invention, the reinforcing fibers B are preferably arranged in roll form on braked unwinding rollers upstream of the temperature and pressure application area, and are fixed and tensioned as a consolidated stack by an automatic take-off system downstream of the temperature and pressure application area.

[0136] The consolidation associated with process step iv), in addition to the one-dimensional production advance, is crucial for the process according to the invention. Consolidation, in the broader sense, is a bonding process in which physical processes lead to the formation of strength at the joint between matrix M and the at least one sheet-like structure F. Essentially, four key mechanisms occur during consolidation: fiber impregnation, laminate compaction, molecular penetration, and solidification.

[0137] The impregnation of the reinforcing fibers B used according to the invention in the sheet F is not used during consolidation if pre-impregnated semi-finished fiber products, so-called prepregs or "preimpregnated fibers," are used as the sheet F, and not dry semi-finished fiber products. The literature often does not distinguish between the terms consolidation and impregnation because laminate compaction and molecular penetration only account for a small portion of the total consolidation time. This share of laminate compaction and molecular penetration in the overall process is usually quantified at around 1%. Accordingly, the consolidation process can also be directly referred to as an impregnation process. Short processing cycle times can therefore be achieved primarily through the use of pre-impregnated semi-finished products or sheet-like structures.

[0138] During laminate compaction, the surfaces of the thermoplastic molding compound as the matrix plastic and the reinforcing fibers B of the sheet F are joined together under high consolidation pressure and at high temperature until complete, intimate contact has developed. This can result in problematic air inclusions. Air or other gas inclusions can only be minimized by applying the consolidation pressure and / or, if necessary, a vacuum. The intimate contact that develops during laminate compaction ideally means that surface roughness of the joining partners, in this case the matrix polymer and the sheet, is leveled out so that contact can develop over the entire surface. Good contact between the joining partners is important because a mechanically resilient connection can only be created in the contact areas.Although complete, intimate contact could be achieved with low consolidation pressures, this would increase the process times.

[0139] Only then does the molecular penetration of the sheet F begin in the areas where an intimate contact between the matrix polymer and the sheet F has already developed. Due to thermal activation and the associated increased mobility of the molecules in the matrix, the molecular penetration leads to an interdiffusion of polymer chains into adjacent layers, whereby the chain ends of the polymer of the thermoplastic molding compound used as the matrix can form new entanglements and entanglements with chains of the polymer(s) of the adjacent layer.

[0140] Molecular interpenetration resulting from the diffusion of polymer chains and the resulting formation of autohesion is not only time-dependent; it also typically requires flow effects as a driving force, particularly microflow movements due to the applied consolidation pressure. After molecular interpenetration, the laminate is cooled in the final step, thus becoming dimensionally stable (solidification). The resulting pore volume, minimized by the application of consolidation pressure, is essentially retained at the end of the consolidation phase due to the cooling.

[0141] However, process-related, thermally induced residual stresses and deformations can also remain frozen in the fiber composite material. It is also important that amorphous thermoplastics retain the molecular orientation they last assumed during diffusion upon cooling, whereas semi-crystalline thermoplastics recrystallize upon cooling from the molten state. The cooling rate also determines the degree of crystallization and the formation of spherulites in process step iv). The degree of crystallization is the proportion of the thermoplastic molecular structure that is present in crystalline form. The mechanical and chemical properties (solvent resistance, etc.) of semi-crystalline thermoplastic compounds ultimately depend significantly on this.The consolidation of thermoplastic materials used as matrix M according to the invention is thus a highly nonlinear process, as it involves the aforementioned different physical processes, some of which occur simultaneously. These processes have a significant influence on the final composite quality and thus on the fiber composite material produced according to the invention.

[0142] Inadequate consolidation can lead to consequences such as trapped pores, residual stresses, deformations, particularly warpage, and in some cases, premature mechanical failure of the fiber composite material. In order to enable an accurate prediction of consolidation, meaningful models for the processes involved are therefore essential. Such process models provide an input-output relationship between the process parameters and the quality of the molded part T to be produced from a fiber composite material according to the invention, thereby reducing cost-intensive "trial and error" optimizations on the technical systems used according to the invention. A reliable prediction of the quality of a molded part T obtained from the simulation thus offers an effective way to optimize process step iv) or process steps (iv) to (vi).This allows us to determine whether the consolidation quality meets the standards applied to the molded part F to be manufactured. A complete simulation of the consolidation process therefore takes into account laminate densification, pore compaction, geometric deformation, molecular interpenetration, thermal degradation, crystallization, as well as residual stresses and warpage. While mathematical models cannot completely replace physical experiments, in combination they allow for a simple parameter study that provides process-critical information that otherwise cannot be measured directly, or can only be measured with great difficulty and time-consuming.

[0143] Process steps iv) and v), in particular the consolidation, are carried out at temperatures of at least 200°C, preferably at temperatures of at least 250°C and particularly preferably at temperatures of at least 300°C.

[0144] Process steps iv) and v), in particular the consolidation, are carried out at pressures in the range from 1 bar to 1000 bar, preferably in the range from 5 bar to 500 bar, particularly preferably in the range from 10 bar to 50 bar.

[0145] Process steps iv) and v) are preferably carried out with a residence time of 1 to 60 seconds. The process according to the invention is preferably carried out with a residence time during process steps ii) to v) of a maximum of 10 minutes at temperatures of at least 200°C, preferably a maximum of 5 minutes, particularly preferably a maximum of 2 minutes, and especially preferably a maximum of 1 minute. For higher temperatures, correspondingly shorter residence times apply, which the person skilled in the art must select depending on the particular thermoplastic to be used.

[0146] For the reaction of the chemically reactive functionalities of the thermoplastic molding compound A in the matrix M with the reinforcing fibers B, which begins in process step v), the polar groups on the surface of the reinforcing fibers B treated with a silane size are important.

[0147] The sizing applied to the reinforcing fibers for this purpose is an impregnating liquid, which is applied to the reinforcing fibers B, particularly by spraying or dipping, before their further processing into the fabric used according to the invention. A sized fiber is more supple and more resistant to mechanical stress. Without sizing, a warp thread can easily become brittle and eventually break due to the constant friction with the weft thread.

[0148] During the production of glass fibers, they are preferably drawn from the melt at high speed. The thickness of the fibers is determined by the size of the nozzles and the draw-off speed. The hot fibers are cooled by spraying them with water, moistened with sizing via a dipping roller, and the individual filaments are immediately bundled into rovings. The sizing has several functions. The rovings are bonded together by the sizing binders, giving them sufficient stability against abrasion during transport and against individual fibers tearing out of the roving or breaking. Since the sizing usually contains water as a diluent, the rovings must be dried. For this purpose, they are either wound wet into so-called "cakes" and then dried, or processed wet and later dried. The glass fibers obtained in this way can then be incorporated into thermoplastics for reinforcement.As a rule, the weight proportion of sizing in the dried glass fiber is in the range of 0.1 to 10 wt.%.

[0149] Process step vi)

[0150] In process step vi), the fiber composite material is cooled, and further process steps may follow. Further process steps preferably include the production of a molded part T. According to a preferred embodiment, the process then comprises, as a further process step, three-dimensional shaping into a molded part T.

[0151] The three-dimensional shaping can be carried out in any desired manner, for example by mechanical shaping using a shaping body, which can also be an embossed roller. Preferably, the cooled fiber composite material obtainable by process step vi) is processed in a further process step, in particular by means of commercially available cutting methods, preferably shearing, waterjet, laser, or ultrasonic cutting, and then heated to a temperature such that the fiber composite material becomes moldable and the thermoplastic molding compound A is (partially) molten and can be molded in the shaping body, in particular a two-part steel tool. Alternatively or additionally, a cured fiber composite material can also be cold-formed.

[0152] Preferably, at the end of the process according to process step vi) a (largely) solid fiber composite material plate is obtained.

[0153] Further processing steps or even cooling under pressure can be performed at a later time or at a different location. Optionally, the molded part T can be further processed, in particular by deburring, polishing, or coloring.

[0154] The process according to the invention comprising process steps i) to vi) can be carried out continuously, semi-continuously, or discontinuously. According to a preferred embodiment, the process is carried out as a continuous process, in particular as a continuous process for producing smooth or three-dimensional fiber composite panels.

[0155] Alternatively, molded parts T can also be manufactured semi-continuously or discontinuously. In the case of fiber-reinforced composites based on an amorphous, thermoplastic matrix M, these can be provided with ribbing in an injection molding process or laminated (welded) onto a foamed, thermoplastic core or a honeycomb core as cover layers. An improvement in component rigidity through ribbing (formation of a ribbed structure) is due to the increase in the area moment of inertia. In general, optimal rib dimensioning incorporates production-related, aesthetic, and design considerations.According to a particularly preferred embodiment, the present invention relates to the process according to the invention for producing a thermoplastic fiber composite material, wherein component A is produced from 90 to 99.7% polypropylene and 0.1 to 10% maleic anhydride, wherein the sheet F is a woven fabric and the residence time for producing the fiber composite material at temperatures of at least 150°C is a maximum of 10 minutes.

[0156] The invention preferably relates to a process for producing a fiber composite material containing a thermoplastic molding compound A as a polymer matrix M, reinforcing fibers B comprising the steps i) providing at least one sheet-like structure F in the form of a woven fabric made of reinforcing fibers B treated with silane sizing, ii) providing a thermoplastic molding compound A serving as matrix M which has at least 0.3 mol%, based on component A, of a chemically reactive functionality in the form of functional monomers, iii) optionally incorporating at least one additive C into the thermoplastic molding compound A, iv) introducing the thermoplastic molding compound A serving as matrix M into the at least one sheet-like structure F by embedding the thermoplastic molding compound A in the reinforcing fibers B by means of a relative movement,in which the reinforcing fibers B remain immobile except for a continuous or discontinuous one-dimensional production feed, and consolidating this composite from at least one sheet-like structure F and the matrix M, v) reaction of the chemically reactive functionalities of the thermoplastic molding compound A with the polar groups on the surface of the reinforcing fibers B treated with a silane size, vi) cooling the fiber composite material and optionally further process steps, wherein the chemically reactive functionality of the thermoplastic molding compound A is based on maleic anhydride, and steps iv) to vi) are carried out at a temperature of at least 150°C and steps v) to vi) are carried out by pressing under excess pressure and the thermoplastic molding compound contains 90 to 99.7 wt.% polypropylene and 0.1 to 10 wt.% maleic anhydride and 0 to 40 wt.%, preferably 0.Contains 1 to 25% by weight of at least one additive C. Preferably, 5 to 90% of the sheet-like structures F made of reinforcing fibers B are used for 10 to 95% by weight of the thermoplastic molding compound A.

[0157] In a further embodiment, additional groups of reinforcing fibers B are coupled to the matrix M via additional, different fiber-matrix bonds. If three or more groups of reinforcing fibers B with different fiber-matrix bonds are used, the behavior of the fiber composite material can be further influenced in a targeted and highly customized manner and adapted to the specific application of the fiber composite material. Different fiber types or the same fiber types can be used in each case.

[0158] Likewise, warp and weft threads may consist of different reinforcing fibers and / or differ in thickness. Furthermore, the warp and weft threads may have been treated with different sizing agents or different sizing concentrations.

[0159] Groups of reinforcing fibers B can each be provided with different adhesion promoter compositions, which result in different fiber-matrix bonds. The different compositions can differ solely in their concentrations or can also have different compositions. What is important is that the different adhesion promoter compositions achieve significantly different fiber-matrix bonds.

[0160] The invention is described in more detail in the following examples, figures and claims.

[0161] Figures

[0162] Fig. 1 shows a fiber composite material (1) obtained using the process according to the invention. The length of the fiber composite material (1) is the extension in direction (2), where (2) simultaneously represents the skin direction of the continuous fibers used in the fabric F. (3a) and (3b) are examples of the course of a continuous fiber moving within the window (4). The fiber composite material (1) obtainable using the process according to the invention is characterized by the height of the window (4) of a maximum of 15%, particularly preferably a maximum of 5%, of the length (2) of the fiber composite material (1).

[0163] Fig. 2 shows a sheet F exhibiting the fiber distortion typical of relative fiber movements. Fig. 3 shows a fiber composite material obtainable according to the invention, in which the relative movements of the reinforcing fibers B of the sheet F were prevented by embedding the thermoplastic molding compound into the reinforcing fibers through a relative movement, during which the reinforcing fiber B remained immobile except for a one-dimensional production feed, and consolidating this composite.

[0164] Examples

[0165] The process according to the invention can be carried out on a double-belt, interval or static press which is capable of quasi-continuously producing a fibre / film composite from polymer film, melt or powder.

[0166] Producible laminate thickness: 0.1 to 15.0 mm

[0167] Output: 0.1 - 1000 m / h, depending on quality and component thickness

[0168] Tool pressure: Press unit 2 to 60 bar, continuously adjustable for minimum and maximum tool size (optional)

[0169] Tool temperature control: at least one heating and at least one cooling zone Tool temperature: up to 500°C

[0170] The flexural strength was determined according to DIN 14125:2011 -05 in the three-point bending test or four-point bending test.

[0171] See: https: / / de.wikipedia.org / wiki / Biegefestigkeit

[0172] Components:

[0173] A1 : Polypropylene with a melt flow rate (Melt Volume Rate, MVR) of 100 cm 3 / 10 min at 230°C / 2.16kg (measured according to IS01 133).

[0174] A2: Maleic anhydride (MSA)

[0175] A3: Mixture of A1 and A2, concentration of functional groups: 3% MSA

[0176] B1 : Glass fiber twill fabric 2 / 2 with a basis weight of approx. 600 g / m 2, weft + warp = 1200tex [for example GW123-580K2 from PD Glasseiden GmbH]

[0177] The combination of A1 and B1, as well as A3 and B1, is compared in Table 1 with regard to the achieved flexural rigidity. Both combinations were manufactured using identical processing parameters (pressure, time, and temperature). Flexural rigidity is a parameter used to evaluate the quality of fiber-matrix adhesion and thus the mechanical component quality. For combinations A1 + B1 and A3a + B1a, the tested panels were manufactured on a static press, with the reinforcing fibers being processed according to the state of the art and thus not warp-free (represented by "a"). The combination A3b + B1b was manufactured using a production technique that ensured the warp-free state of the reinforcing fibers according to process step iv) of the process claimed here (represented by "b"). Table 1

[0178] It was found that the process according to the invention made it possible to obtain a fiber composite (material) which, in terms of its flexural strength, was 26% superior to a fiber composite (material) based on the same matrix and the same reinforcing fibers, but not produced using process step iv) but according to the process in EP 3 286 258 B1.

[0179] Optional further processing

[0180] It was also experimentally demonstrated that the fiber composites obtained by the inventive process were readily formable into three-dimensional semi-finished products, such as half-shell-shaped semi-finished products. It was also shown that the resulting fiber composites were printable and laminateable.

[0181] Summary of test results

[0182] The evaluation within the scope of the present invention has shown that fiber composite materials with improved flexural strength, i.e., organic sheets and semi-finished products produced therefrom, could be reproducibly produced using process step iv). Fiber composites (materials) according to the invention could be produced both colorless and colored. The fiber composites (materials) also exhibited good to very good optical, haptic, and mechanical properties, particularly with regard to their flexural strength. Fiber distortion, which typically occurs in sheet-like structures F, could be successfully prevented using the inventive manufacturing process, as a result of which the fiber composite (material) exhibited only minimal fiber distortion. The fiber composites (materials) obtainable according to the invention could be produced semi-automatically or fully automatically using a continuous process.The fiber composite materials (organic sheets) obtainable according to the invention can be easily formed into three-dimensional semi-finished products.

Claims

Patent claims 1. A process for producing a fiber-reinforced composite material comprising a thermoplastic molding compound A as a polymer matrix M and reinforcing fibers B, comprising the steps of: i) providing at least one sheet F in the form of a fabric made of reinforcing fibers B treated with silane sizing; ii) providing a thermoplastic molding compound A serving as matrix M, which has at least 0.3 mol%, based on component A, of a chemically reactive functionality in the form of functional monomers; iii) optionally incorporating at least one additive C into the thermoplastic molding compound A; iv) introducing the thermoplastic molding compound A serving as matrix M into the at least one sheet F by embedding the thermoplastic molding compound A into the reinforcing fibers B by means of a relative movement in which the reinforcing fibers B remain immobile except for a continuous or discontinuous one-dimensional production feed.and consolidating this composite consisting of at least one planar structure F and the matrix M, v) reaction of the chemically reactive functionalities of the thermoplastic molding compound A with the polar groups on the surface of the reinforcing fibers B treated with a silane sizing, vi) cooling of the fiber composite material and optionally further process steps, wherein the chemically reactive functionality of the thermoplastic molding compound A is based on components selected from the group consisting of maleic anhydride, N-phenylmaleimide and glycidyl (meth)acrylate, and steps iv) to vi) are carried out at a temperature of at least 150°C and steps v) to vi) are carried out by pressing under overpressure.

2. Method for producing a thermoplastic fiber composite material according to claim 1, characterized in that the thermoplastic molding compound A is based on amorphous or semi-crystalline plastic.

3. Method for producing a thermoplastic fiber composite material according to claim 2, characterized in that the thermoplastic molding compound A is based on at least one polymer of the group consisting of polyolefins, polyamides, thermoplastic elastomers, polycarbonates, polybutadiene terephthalates, polylactides, polyphenylene sulfides and styrene copolymers.

4. Method for producing a thermoplastic fiber composite material according to claim 3, characterized in that polypropylene is used as the polyolefin.

5. Method for producing a thermoplastic fiber composite material according to one or more of claims 1 to 4, characterized in that reinforcing fibers B treated with a silane sizing are used.

6. Method for producing a thermoplastic fiber composite material according to claim 5, characterized in that glass fibers are used as reinforcing fibers B.

7. Method for producing a thermoplastic fiber composite material according to claim 6, characterized in that the glass fibers used as reinforcing fibers B have silanol groups on their surface as a chemically reactive functionality.

8. Method for producing a thermoplastic fiber composite material according to one or more of claims 1 to 7, characterized in that the method, in particular process steps iv) and v) or optionally also process step vi), is carried out on a double belt press, interval heating press or on a static press.

9. Method for producing a thermoplastic fiber composite material according to one or more of claims 1 to 8, characterized in that the temperature during the production of the fiber composite material is at least 150°C, preferably at least 200°C and particularly preferably at least 250°C.

10. A method for producing a thermoplastic fiber composite material according to one or more of claims 1 to 9, characterized in that the residence time during the production of the fiber composite material at temperatures of at least 200°C for a maximum of 10 minutes, preferably a maximum of 5 minutes, particularly preferably a maximum of 2 minutes and especially a maximum of 1 minute. 1 1 . Method for producing a thermoplastic fiber composite material according to one or more of claims 1 to 10, characterized in that the relative movement of the thermoplastic molding compound A in relation to the reinforcing fibers B is achieved by fixing the reinforcing fibers B in the direction of the relative movement.

12. Method for producing a thermoplastic fiber composite material according to claim 1 1 , characterized in that the fixing of the reinforcing fibers B in front of and behind the area in which the movement of the thermoplastic molding compound A is generated by a surface pressure > 10 bar at a temperature of at least 10°C above the crystallite melting temperature or glass transition temperature in the case of amorphous thermoplastics is effected by means of mechanical clamping, winding or with the aid of fastening elements and this fixing is held under constant tension by applying opposing forces.

13. Method for producing a thermoplastic fiber composite material according to claim 1 or 12, characterized in that the reinforcing fibers B are fixed in their position such that the tension in the longitudinal direction prevents movement in all spatial directions.

14. Method for producing a thermoplastic fiber composite material according to one or more of claims 1 to 13, characterized in that the reinforcing fibers B in the form of fabrics are fixed and held under tension in a roll-like manner on braked unwinding rollers before the area of ​​temperature and pressure application and behind the area of ​​temperature and pressure application as a consolidated stack by an automatic take-off system.

15. A method for producing a thermoplastic fiber composite material according to one or more of claims 1 to 14, characterized in that the chemically reactive functionality of the thermoplastic molding compound A is based on maleic anhydride and steps iv) to vi) are carried out at a temperature of at least 150°C and steps v) to vi) are carried out by pressing under overpressure and the thermoplastic molding compound contains 90 to 99.7 wt.% polypropylene and 0.1 to 10 wt.% maleic anhydride as well as 0 to 40 wt.%, preferably 0.1 to 25 wt.%, of at least one additive C.

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