FILM ADHESIVE AND METHOD FOR THE PRODUCTION THEREOF

Description

[0001] The invention relates to a film adhesive for the material-bonded joining of at least two joining partners, wherein the film adhesive comprises an adhesive for bonding the joining partners and a textile, planar carrier material onto which the adhesive is applied in a film-like form. The invention also relates to a method for producing such a film adhesive and a method for producing an adhesive bond using such a film adhesive.

[0002] Due to their high strength-to-weight ratio and stiffness, fiber-reinforced composites are virtually indispensable in the production of all kinds of components. Fiber-reinforced composites consist primarily of two main components: a fiber material and a matrix material, and may also contain other components (depending on the application). In the production of fiber-reinforced composite components, the fiber material is typically formed into the desired component shape, and then the matrix material infused into the fiber material is cured. Curing is almost always achieved through temperature and, if necessary, pressure. During curing, the load-bearing fibers of the fiber material are forced into their predetermined orientation and, together with the cured matrix material, form an integral unit for load transfer.

[0003] Adhesive bonding is a joining method with significant lightweight potential, not only in the production of complex fiber-reinforced composite components. Using an adhesive bond, two components are firmly and generally permanently joined at their respective joining surfaces through cohesion and / or adhesion. Further mechanical fasteners can only be dispensed with if the failure of the adhesive bond is insignificant for the operation of the underlying technical equipment. Validating the strength and durability of adhesive bonds is a key challenge for adhesive technologies, as incorrect or insufficient surface treatments, expired or improperly processed adhesives, and contamination can significantly reduce bond strength.Especially in the aviation sector, in the manufacture of aircraft, particularly from fiber-reinforced composite materials, where structural components are also manufactured using adhesive bonds, it is essential that the adhesive bond has strength and durability, as in the event of damage to such an adhesive bond, safe flight operations can no longer be guaranteed.

[0004] Thus, operational loads in contaminated areas of the adhesive bond can lead to local separation of the joint with subsequent crack growth through the entire adhesive seam, thereby greatly reducing the load-bearing capacity of the adhesive bond up to and including complete failure of the adhesive bond.

[0005] In aviation, it is therefore common practice to secure the adhesive bond at certain intervals with additional mechanical fasteners ("safety rivets"), which, however, directly contradicts the principle of lightweight construction. The benefit that the adhesive bond is intended to achieve—namely, saving fuel and thus costs through weight reduction during flight operations—is negated by these additional mechanical fasteners.

[0006] German patent DE 10 2013 107 849 A1 discloses a method for producing a fiber composite structure from at least two separately manufactured fiber composite components, which are to be joined together by adhesive bonding. Two different adhesive systems are used, which are introduced into the adhesive bond in such a way that separate adhesive zones are formed from the first and second adhesive systems. In the cured state, the second adhesive system exhibits higher fracture toughness than the first adhesive system, resulting in different properties within the adhesive bond. In areas with low fracture toughness and high strength (first adhesive system), any cracks that develop can only propagate into the areas of the second adhesive zone, where the adhesive bond exhibits high fracture toughness (tough-elastic) but reduced strength and stiffness.Cracks that form in the adhesive seam can thus be effectively limited to a local area.

[0007] The disadvantage here, however, is that applying two different adhesive systems, each bordering the other, is very complex, which in turn leads to longer joining times and thus higher costs. Furthermore, when creating such adhesive bonds, great care must be taken during the application of the adhesive, as the adjacent, different adhesive systems should ideally meet without gaps to avoid load bridging in this area. In addition, the elongation at break properties change abruptly at the edges of the adhesive zones, which promotes crack propagation along the edges.

[0008] From EP 2 324 979 A1, a preform and a corresponding manufacturing process are known, wherein the preform comprises several layers of a semi-finished textile product. It is disclosed that the fiber material or the matrix material of the preform contains corresponding additives to influence, for example, the viscosity or other mechanical properties of the matrix material. Furthermore, German patent application D1 provides that the layers of the preform are stacked on top of each other in such a way that a kind of ramp is created in the edge regions.

[0009] WO 02 / 088231 A1 or EP 1 381 641 A1 discloses a fiber material (prepregs) for the production of a fiber composite component using a molding tool, wherein the fiber material has first areas which have a high proportion of matrix material and second areas which have a low proportion of matrix material.

[0010] US patent 2013 / 0101805 A1 discloses a multilayer fiber material that is intended to have correspondingly different properties. It also includes a component that connects several other layers via an intermediate layer. Finally, US patent 2015 / 0147536 A1 discloses a component for the manufacture of car roofs, which also incorporates several layers of fiber material with different properties.

[0011] It is therefore an object of the present invention to provide an improved method for reliably joining two components by means of adhesive bonding, wherein the adhesive bond to be produced is to have crack-stopping or crack-inhibiting properties. It is therefore also an object of the present invention to provide an improved adhesive system and a method for its production in order to produce such an adhesive bond. This object is achieved according to the invention with the film adhesive according to claim 1, the method for its production according to claim 5, and the method for producing an adhesive bond according to claim 8.

[0012] According to claim 1, a film adhesive for bonding and joining at least two components is proposed, wherein the film adhesive comprises an adhesive for bonding the components and a textile, planar carrier material, the adhesive being applied to the textile, planar carrier material in a film-like manner. The adhesive is applied to the textile carrier material in such a way that the textile, planar carrier material is completely covered by the adhesive, at least on the planar sides of the textile carrier material that face the joining surfaces of the two components. In the film adhesive, the textile, planar carrier material serves in particular as a spacer for a predefined and predetermined strength or thickness of the adhesive bond. The adhesive bond is achieved exclusively by the adhesive, whereby the textile, planar carrier material does not serve as a connection between the two components.The adhesive bond is achieved solely through the adhesive. For example, it is conceivable that the textile, flat substrate material is completely encased in the adhesive and thus fully saturated with it, whereby porous substrate materials, such as open-pored fiber materials, are particularly suitable.

[0013] For processing the film adhesive, it can be advantageous if, in its uncured state, the textile substrate protrudes at least partially from the adhesive and is therefore not completely pre-impregnated. This ensures that, in the uncured state of the adhesive, the textile substrate is at least partially impregnated, so that after the adhesive has cured, the textile substrate is completely encased by the cured adhesive.

[0014] The adhesive is, in particular, a self-curing adhesive material that can form a suitable bond with the components being joined. Specifically, only a single adhesive system is used for the film adhesive, meaning that the entire film adhesive contains only one adhesive material that is intended to form the subsequent bond. The adhesive material is therefore a homogeneous material. Unlike conventional adhesive tapes, such as packaging tape, the textile, sheet-like backing material is not a component that serves as an aid in the adhesive bonding process.In conventional adhesive tapes, particularly double-sided tapes, an adhesive material is applied to a substrate, usually made of plastic. This results in a bond between two substrates being joined using double-sided tape, which essentially consists of two separate bonds: one between the first substrate and the plastic substrate, and another between the plastic substrate and the second substrate. In contrast, the present invention achieves the adhesive bond solely through the adhesive. The textile substrate does not act as a substrate in the traditional sense. Instead, it serves as a carrier for the adhesive and as a spacer to maintain a defined thickness of the bond.

[0015] According to the invention, the textile, planar support material has at least one first section adjoining at least one second section of the support material, wherein the support material of the first section is materially, chemically and / or geometrically modified compared to the support material of the second section such that, after the adhesive has cured, the adhesive joint in the area of ​​the first section has a mechanical property with respect to elongation at break or fracture toughness that differs from the mechanical property of the adhesive joint in the area of ​​the second section, i.e., is either higher or lower.

[0016] A film adhesive is thus proposed that produces an adhesive bond similar to that of DE 10 2013 107 849 A1, exhibiting corresponding crack-stopping properties. This is achieved by incorporating areas with altered elongation at break or fracture toughness, without the adhesive itself necessarily consisting of two different adhesive systems. Rather, it has been recognized that a single adhesive system can be used through a material, chemical, and / or geometric modification of the textile substrate. However, during curing, this system interacts with the modified material, chemical, and / or geometric elements in such a way that the adhesive bond exhibits higher or lower elongation at break or fracture toughness in these modified areas, thereby imparting crack-stopping properties to the entire adhesive bond.This is because a crack propagating in a section of the adhesive bond usually originates in those areas where there is high stiffness and low elongation at break or fracture toughness, whereby such a crack only propagates to those adjacent areas or sections where the stiffness or strength of the adhesive bond is reduced, but the elongation at break or fracture toughness is increased.

[0017] This allows for the creation of a film adhesive that is very easy to produce, as it uses only a single homogeneous adhesive applied to a substrate. The modification of the adhesive during curing, resulting in the formation of a bond, is achieved through the material, chemical, and / or geometric modification of parts of the substrate, creating distinct sections. This modification enables the creation of adhesive bonds with crack-stopping and crack-inhibiting properties.

[0018] The novel film adhesive enables the creation of an adhesive bond in which areas with high strength properties are surrounded by sections with tough-elastic properties. In contrast to the technical teaching of DE 10 2013 107 849 A1, which aims to achieve clearly defined material properties in the different adhesive zones, the modification of the carrier material during the curing of the adhesive in the bond creates a property gradient between the first and second sections, thereby preventing crack propagation in the edge region. This is because the prior art solution exhibits an abrupt change in the properties with respect to elongation at break or fracture toughness in the edge region of the different adhesive zones, whereas the present invention provides a smooth transition from areas of low elongation at break or fracture toughness and high strength to areas of high elongation at break or fracture toughness.high fracture toughness and tough-elastic properties.

[0019] The property gradient between the first and second sections, i.e., the gradual transition of the respective property, ensures load transfer at the crack tip. In chemical reactions between the adhesive and the applied material, the gradient can form naturally through diffusion, for example. With geometric modification, the transition from the thin to the thick area can be designed with a corresponding gradient. For example, with applied particles, these can be distributed in a defined pattern, so that, for instance, with a linear application of particles, there are many particles in the middle of the line, and the quantity or concentration gradually decreases towards the edge of the line.

[0020] As already mentioned, the substrate material of the first section can be modified compared to the substrate material of the second section in such a way that the adhesive bond, after curing, has a higher elongation at break or a higher fracture toughness in the area of ​​the first section than the adhesive bond in the area of ​​the second section, so that a crack or defect in the adhesive bond within the second section does not propagate beyond the area of ​​the first section of the adhesive bond, since the adhesive bond has a higher fracture toughness or elongation at break here than in the areas of the second section. InIn this case, an adhesive with high strength and low elongation at break or fracture toughness is used, which is modified accordingly in the areas of the first sections so that areas with high fracture toughness or elongation at break are created, which then inhibit or stop the propagation of cracks.

[0021] Of course, it is also conceivable to use an adhesive that inherently exhibits high elongation at break or fracture toughness, although this reduces the adhesive's stiffness or strength. The modification in the areas of the first section then increases the stiffness or strength of the adhesive in those areas, so that the second sections in this embodiment then possess crack-inhibiting or crack-stopping properties.

[0022] InIn an advantageous embodiment, the fracture toughness or elongation at break is modified by altering the carrier material so that it is at least 20%, preferably at least 50% higher or lower than in the unmodified sections.

[0023] In In another advantageous embodiment, the stiffness or strength is changed by modifying the support material so that it is at least 20%, preferably at least 50% higher or lower than in the unmodified sections.

[0024] In In an advantageous embodiment, the textile, planar support material has a plurality of first sections, each of which is separated from one another by one of the second sections, so that separate zones are formed by the first sections which are not connected to each other.

[0025] Preferably, the sections are delimited from one another in such a way that those sections exhibiting crack-stopping or crack-inhibiting properties separate the other sections from each other, preventing them from being connected. This is because a crack or defect in the adhesive bond always originates in the areas that lack crack-inhibiting or crack-stopping properties. Therefore, the delimitation with the sections possessing crack-inhibiting or crack-stopping properties is intended to prevent the crack from propagating throughout the entire adhesive bond.

[0026] Therefore, the first sections are preferably arranged on the carrier material in such a way that the first sections and / or second sections form separate zones that inhibit or stop the propagation of cracks throughout the entire adhesive bond and prevent such complete propagation.

[0027] It is conceivable that the first sections on a ribbon-shaped film adhesive are arranged in such a way that the first and second sections alternate along the longitudinal axis of the ribbon-shaped film adhesive, so that two second sections are separated from each other by a first section (and vice versa).

[0028] One aspect of the invention is that the textile planar support material in one of the first sections is materially modified in such a way that the material of the support material in these areas is a material which undergoes a chemical reaction with the adhesive when it cures, in order to effect the desired mechanical property in these first sections and to change it accordingly compared to the areas of the second sections.

[0029] This can be achieved, for example, by using a substrate material in these initial stages that reacts with the embedded adhesive during curing to produce the desired property of the adhesive bond. For instance, it is conceivable that fiber yarns or other linear structures, distinct from the rest of the material, are used in the production of the textile substrate. These fibers then undergo a chemical reaction with the adhesive to achieve the desired property.

[0030] It is conceivable that in the modified section, either high strength and stiffness are achieved, which often results in a reduction of elongation and fracture toughness (a negative effect). These highly stiff and high-strength sections then represent the load-bearing areas. Alternatively, elasticity and elongation at break are increased, which generally results in increased fracture toughness and a reduction in strength. However, the local reduction in stiffness is considered advantageous in the present invention.

[0031] The invention's functionality is based primarily on the alternating stiff and elastic regions. The stiff regions bear a large portion of the load, while the elastic regions inhibit crack propagation after reaching its maximum. Due to their high elasticity and elongation at break, the elastic regions undergo greater deformation and can thus transfer a large portion of the load to the underlying stiff regions. Simultaneously, they relieve the stiff regions, as they themselves already bear a portion of the load. In this way, the two distinct regions share the load and can bear it together, instead of failing sequentially under individual stress.

[0032] By modifying the carrier material, the properties of the adhesive can be specifically influenced in such a way that either the stiffness and strength are specifically increased and thus load-bearing areas are formed, or the elasticity is specifically increased and thus crack-stopping areas are formed.

[0033] Another aspect of the invention is that the textile substrate is chemically modified in one of the first sections such that additional substances, particles, and / or fillers are added to the substrate in this area(s), which undergo a chemical reaction with the adhesive during curing to achieve the desired mechanical properties in the first sections. For example, it is conceivable that additional substances are added to the substrate by coating the substrate in the first sections with these substances, whereby these substances then modify the adhesive during curing so that it exhibits a higher or lower elongation at break than in the other sections of the film adhesive.It is also conceivable that the spacer fabric is locally coated with adhering foreign particles, which, due to the reduced viscosity of the adhesive during the curing process, become embedded in the adhesive seam and thus cause the modification. Another possibility is the local coating of the textile substrate with a polymer of lower stiffness, which, during the curing of the adhesive film, bonds with the surrounding adhesive and thus causes the local change in properties.

[0034] Another aspect of the invention is that the textile substrate material is geometrically modified in one of the first sections such that the substrate material in these areas results in a greater or lesser thickness of the adhesive bond after the adhesive has cured than in the areas of the second sections. It was thus recognized that varying the adhesive film thickness can also alter the properties with respect to elongation at break and fracture toughness, so that a geometric modification of the substrate material can also achieve a modification of the elongation at break and fracture toughness.

[0035] Increasing the adhesive film thickness, for example, does not change the adhesive properties themselves. However, since the shear and elastic moduli of the joining partners are significantly higher than those of the adhesive in typical adhesive bonds, increasing the adhesive layer thickness leads to a reduction in the stiffness of the joint. This, in turn, increases the elongation at break and fracture toughness, thus giving this first area a crack-stopping or crack-inhibiting property through increased adhesive layer thickness.

[0036] The problem is also solved according to the invention by the method of claim 5 for producing such a film adhesive, wherein a provided adhesive is applied in a film-like manner to a provided flat textile substrate, so that the textile substrate is wetted on both sides with the adhesive. Here, too, the adhesive serves to create the adhesive bond, without the textile substrate becoming a joining partner.

[0037] According to the invention, it is provided that the textile, planar carrier material is modified in at least a first section compared to at least a second section in such a material, chemical and / or geometric way that, at the latest after the adhesive has cured, the adhesive joint in the area of ​​the first section has a mechanical property with regard to elongation at break or fracture toughness that differs from the mechanical property of the adhesive joint in the area of ​​the second section.

[0038] Here too, the material, chemical and / or geometric modification of the carrier material leads to a corresponding change in the adhesive's properties when interacting with the adhesive, in order to obtain a different property with regard to elongation at break or fracture toughness compared to other areas.

[0039] Advantageous embodiments of this method can be found in the corresponding dependent claims.

[0040] The problem is also solved by the method according to claim 8 for producing an adhesive bond between at least two joining partners, wherein a film adhesive as described above is first provided. The adhesive of the film adhesive is then contacted with the respective joining surface of the joining partners, whereby an adhesive bond is then effected between the joining partners by means of the cured adhesive.

[0041] The joining partners can be fiber-reinforced composite components made from a fiber-reinforced composite material. The film adhesive can advantageously have a fiber material as a planar textile carrier material, whereby the adhesive of the film adhesive can then, for example, be a matrix material of a fiber-reinforced composite.

[0042] The invention is explained in more detail using the attached figures as examples. They show: Figure 1 - Schematic representation of a film adhesive; Figure 2 - Schematic cross-sectional representation of a film adhesive; Figure 3 - Schematic representation of an embodiment of the film adhesive; Figure 4 - Schematic representation of a joining method.

[0043] Figure 1 Figure 1 schematically shows a film adhesive 1 wound on a roll 2. The film adhesive 1 has a textile carrier material 3 embedded in an adhesive 4.

[0044] The textile, planar carrier material 3 preferably has dimensions corresponding to the length and width of the film adhesive 1. The textile, planar carrier material 3 can preferably be assembled from linear structures to form a planar structure, as is the case, for example, with woven textiles. The textile carrier material 3 is preferably a flexible material. Depending on the application, however, the carrier material can also be rigid.

[0045] The adhesive 4 is applied to the substrate 3 in such a way that the substrate 3 is preferably completely covered by the adhesive on both surfaces. The substrate 3 is designed to be more or less open-pored, so that after the adhesive 3 has cured, the adhesive bond forms a functional connection from one surface of the substrate to the other surface of the substrate via the adhesive material. As a result, the substrate 3 does not become a component of the adhesive bond, as is the case, for example, with double-sided adhesive tape.

[0046] The carrier material 3 is modified section by section, resulting in first sections 5 within which the carrier material 3 is materially, chemically and / or geometrically modified, while second sections 6 follow these first sections 5 in which the carrier material 3 is not modified.

[0047] By modifying the carrier material 3 in the first sections 5, an interaction with the adhesive 4 is achieved, thereby changing properties with respect to the elongation at break and / or fracture toughness of the adhesive 4 in the areas of the first sections 5 compared to the areas of the second sections 6, in order to achieve a heterogeneous adhesive bond with respect to elongation at break or fracture toughness.

[0048] If the adhesive bond exhibits heterogeneity in terms of elongation at break or fracture toughness in the cured state, areas with high elongation at break and lower stiffness / strength alternate with areas with low elongation at break and high stiffness / strength, meaning that cracks forming within the adhesive bond can only propagate to the next section.

[0049] In order for the film adhesive 1 to be wound onto the roll 2, both flat surfaces of the film adhesive 1 are covered with a release film so that the individual flat surfaces do not stick to each other.

[0050] Figure 2 shows a cross-section AA (see below). Figure 1 ) by a portion of the film adhesive 1, where the first sections 5 are geometrically modified. The in the Figure 2 The modified areas 5 shown in the figures below are not proportional to the remaining unmodified areas 6. In practice, one would produce large areas with high stiffness and strength surrounded by small areas with high elongation at break and fracture toughness. Therefore, the embodiments shown in the figures are not to scale in this respect.

[0051] The planar carrier material 3 is a woven textile with individual fibers that can run lengthwise and crosswise across the film adhesive 1. In the first section 5 of the film adhesive, the fibers 7a located in this area are thicker (larger cross-section than fibers in the second section 6), resulting in an overall thickening of the film adhesive in the first section 5. By varying the adhesive film thickness over the entire length of the film adhesive, the bonding properties of the adhesive joint can be influenced, as the adhesive film thickness affects the bonding properties. Increasing the adhesive film thickness leads to a reduction in the stiffness of the joint, thereby increasing the elongation at break of the joint in the first section 5. By reinforcing or...Thickening the substrate material in the first section 5 allows for a geometric modification of the substrate material, which then leads to the desired change in the properties of the adhesive bond. This results in a modification of the adhesive layer / adhesive seam.

[0052] Figure 3 Figure 1 schematically shows a cross-section through a film adhesive 1 in which the carrier material 3 in the first section 5 has been chemically and / or materially modified such that, when the adhesive 4 cures, it interacts with the chemical and / or material modification in the first section 5 in such a way that the mechanical property of the adhesive bond in this area has been changed compared to the areas of the second section 6.

[0053] In a material modification, the material of the textile carrier material 3 is changed, as in the exemplary embodiment of the Figure 3Thus, fibers 7a are replaced by fibers that have a corresponding modification. Such a modification of fibers 7a could, for example, involve using fibers that contain a chemical substance which reacts with the adhesive during curing.

[0054] It is also conceivable that the carrier material 3 has fibers that are identical in all areas and sections, with corresponding substances being applied to the fibers of the carrier material 3 in the first 5 sections, which then react with the adhesive. Such substances or materials can, for example, be applied in powder or gel form and are present only in these first 5 sections of the carrier material 3.

[0055] This results in a local change in the properties of the adhesive bond in the first sections 5, without the need to work with several different types of adhesive systems.

[0056] It is also conceivable that additional particles or foreign substances are arranged on the fibers, which adhere to the fibers 7a in the first section 5 of the carrier material and interact with the adhesive 4 during curing in such a way that, for example, due to a chemical reaction, the adhesive bond in the first section 5 has altered mechanical properties with regard to elongation at break or fracture toughness compared to the other sections.

[0057] In the lower part of the Figure 3 The cured adhesive bond is shown, wherein in the first section 5 of the carrier material, due to the chemical reaction of the adhesive 4 during curing with the material and / or chemical modification, a changed mechanical property has arisen, which forms in particular around the fibers 7a in the first section 5.

[0058] For example, if one assumes that the modification causes an increase in elongation at break or fracture toughness, then cracks under stress on the adhesive joint usually first form in the second sections 6 of the adhesive joint, whereby cracks formed there can then only propagate to an adjacent area of ​​a first section 5, since the first sections 5 then have an increased fracture toughness or elongation at break and cracks no longer propagate along this section.

[0059] Figure 4 Figure 1 schematically shows the bonding of two joining partners 11 and 12 using such a film adhesive 1 to produce a component 10. The component 10 can, for example, be a fiber composite component which is to be joined by means of the film adhesive 1 using two fiber composite components.

[0060] In the exemplary embodiment of the Figure 4The film adhesive 1 has a geometric modification in the first section 5, such that the adhesive film thickness is increased in the first section 5 of the film adhesive 1, resulting in a higher fracture toughness or elongation at break in this area than in the other sections 6.

[0061] If component 10 is a fiber-reinforced composite component, then the first component 11 and the second component 12 (first joining partner 11, second joining partner 12) are also made of a fiber-reinforced composite material. Thus, in the exemplary embodiment of the Figure 4The first joining partner 11 is already a cured fiber composite component in which the matrix material infused with the fiber material has already cured. The film adhesive 1 is then applied flat and evenly to the joining surface of the first joining partner 11, so that the adhesive 4 of the film adhesive 1 makes contact with the joining surface of the first joining partner 11. Subsequently, the still uncured fiber composite component 12 (second joining partner) is placed onto the film adhesive 1, whereby the fiber material must be draped onto the film adhesive 1 in such a way that the geometric modification in the first section 15 of the film adhesive 1 is taken into account. In other words, the shape deviation caused by the geometric modification of the film adhesive 1 must be compensated for by the second joining partner in the exemplary embodiment of the Figure 4 to be balanced.

[0062] In the exemplary embodiment of the Figure 4The film adhesive 1 is designed such that the geometric modification in the first section 5 only affects one side or one adhesive surface, so that the shape deviation due to the geometric modification only affects one of the joining partners, in the exemplary embodiment of the Figure 4 The second joining partner 12 must be adapted to the shape. However, it is also conceivable that the film adhesive 1 has a geometric modification in which both bonding surfaces have a corresponding shape deviation, so that both joining partners must also be adapted to this shape deviation. In such a case, it is conceivable that the first joining partner 11 is not fully cured in order to compensate for the corresponding shape deviation. It is also conceivable that the joining partners 11 and 12 are provided in such a way that they already have the geometric modification of the film adhesive 1 imprinted on them and can thus accommodate the geometric modification.

[0063] Particularly when joining ductile components (e.g., aluminum sheets), the component can adapt to the spacer fabric during consolidation of the adhesive bond under autoclave pressure or in a press. Joining thermoplastic fiber composite components is also conceivable; these may become plastic under elevated temperature and thus adapt to the adhesive film.

[0064] Any type of textile can be used as the carrier material or spacer fabric, such as nonwovens, woven fabrics, nets, yarns, etc. Material, chemical, and / or geometric modification can be achieved, for example, by incorporating additional carrier material in the form of textiles, nonwovens, woven fabrics, nets, or yarns that have been chemically modified accordingly. Powders, particles, or fillers can also be used, which adhere to the carrier material, for example, by melting or an adhesion promoter. Suspensions are also conceivable. Furthermore, chemical and / or material modification can also be achieved through substances in paste form or as impregnation, e.g., by application at elevated temperature followed by solidification.

[0065] Materials suitable for modification, for example to modify an epoxy resin, include copolyamides, copolyesters, polyetherimide, polysulfone, polyphenylsulfone, and polyethersulfone. These thermoplastics possess advantageous mechanical properties and can form mixed phases with epoxy resins, allowing for processing as textiles, powders, or pastes. Rubbers with hydroxyl groups at the free molecular ends (HTPB, CTBN, ATBN) can dissolve in epoxy and precipitate spherically during the curing reaction due to decreasing solubility. These materials are known as toughness modifiers for epoxy resins. Application to the substrate can be achieved in all the aforementioned forms. Phenoxy (polyhydroxy ether or bisphenol-A-epichlorohydrin with free OH end groups) is a thermoplastic that is soluble in epoxy and can be incorporated into the three-dimensional network structure of the thermoset.It can be applied as a textile, powder, or in paste form.

Claims

1. Film adhesive (1) for the adhesive joining of at least two joining partners (11, 12), which contains an adhesive (4) for an adhesive connection of the joining partners (11, 12) and a textile, flat carrier material (3), the adhesive (4) being applied to the textile, flat carrier material (3) in a film-like manner, characterized in in that the textile, flat carrier material (3) has at least one first section (5) which adjoins at least one second section (6) of the carrier material (3), the carrier material (3) of the first section (5) being modified with respect to the carrier material (3) of the second section (6) in such a way that, after the adhesive (4) has cured, the adhesive bond in the region of the first section (5) has a mechanical property with respect to the fracture strain or fracture toughness which is different from the mechanical property of the adhesive bond in the region of the second section (6), whereby the textile, flat carrier material being completely enclosed and impregnated by the adhesive and being open-pored, so that the adhesive bond is realized exclusively by the adhesive and the carrier material thus does not become a joining partner, - wherein the textile, flat carrier material (3) is materially modified in one of the first sections (5) in such a way that the material of the carrier material (3) in these regions is a material which, when the adhesive (4) cures, undergoes a chemical reaction with the this in order to bring about the desired mechanical property in the first sections (5), - wherein the textile, flat carrier material (3) is chemically modified in one of the first sections (5) in such a way that additional substances, particles and / or fillers are added to the carrier material (3) in this region or regions, which enter into a chemical reaction with the adhesive (4) when the this cures, in order to bring about the desired mechanical property in the first sections (5), and / or - wherein the textile, flat carrier material (3) is geometrically modified in one of the first sections (5) in such a way that the material of the carrier material (3) in these regions is a material which, after the adhesive (4) has cured, produces a higher or lower thickness of the adhesive bond than in the regions of the second sections (6).

2. Film adhesive (1) according to claim 1, characterized in that the carrier material (3) of the first section (5) is modified with respect to the carrier material (3) of the second section (6) in such a way that the adhesive bond in the region of the first section (5) has a higher fracture strain or a higher fracture toughness than the adhesive bond in the region of the second section (6) or that the adhesive bond in the region of the first section (5) has a lower fracture strain or a lower fracture toughness than the adhesive bond in the region of the second section (6), whereby the fracture toughness or fracture strain being at least 20%, preferably at least 50%, higher or lower.

3. Film adhesive (1) according to one of the preceding claims, characterized in that the textile, flat carrier material (3) has a plurality of first sections (5) which are each delimited from one another by one of the second sections (6), so that each first sections (5) form separate zones which are not connected to one another.

4. Film adhesive (1) according to one of the preceding claims, characterized in that the film adhesive (1) is ribbon-shaped and that first and second sections alternate in the longitudinal direction.

5. Method for producing a film adhesive (1) for the adhesive joining of at least two joining partners (11, 12), in which an adhesive (4) for an adhesive connection of the joining partners (11, 12) is applied in the manner of a film to a textile, flat carrier material (3), characterized in that the textile, flat carrier material (3) is modified in at least one first section (5) with respect to at least one second section (6) in such a way that, at the latest after the adhesive (4) has cured, the bonded joint in the region of the first section (5) has a mechanical property with respect to fracture strain or fracture toughness which is different from the mechanical property of the bonded joint in the region of the second section (6), wherein a carrier material which is completely enclosed and impregnated by the adhesive and has open pores is provided as the textile, flat carrier material, so that the adhesive bond is realized exclusively by the adhesive and the carrier material thus does not become a joining partner, - wherein the textile, flat carrier material (3) is materially modified in one of the first sections (5) in such a way that a material is used as the material of the carrier material (3) in these regions which enters into a chemical reaction with the adhesive (4) at the latest when the adhesive (4) cures, in order to bring about the desired mechanical property in the first sections (5), - wherein the textile, flat carrier material (3) is chemically modified in one of the first sections (5) in such a way that additional substances, particles and / or fillers are added to the carrier material (3) in this region or regions, which enter into a chemical reaction with the adhesive (4) at the latest when the adhesive (4) cures, in order to bring about the desired mechanical property in the first sections (5), and / or - wherein the textile, flat carrier material (3) is geometrically modified in one of the first sections (5) in such a way that a material is used as the material of the carrier material (3) in this region or regions which, at the latest after curing of the adhesive (4), produces a higher or lower thickness of the adhesive bond than in the regions of the second sections (6).

6. Method according to claim 5, characterized in that the carrier material (3) of the first section (5) is modified in such a way that the adhesive bond in the region of the first section (5) has a higher fracture strain or a higher fracture toughness than the adhesive bond in the region of the second section (6) or that the adhesive bond in the region of the first section (5) has a lower fracture strain or a lower fracture toughness than the adhesive bond in the region of the second section (6), wherein the fracture toughness or fracture strain is higher or lower by at least 20%, preferably by at least 50%.

7. Method according to one of claims 5 or 6, characterized in that a plurality of first sections (5) are formed, which are each delimited from each other by one of the second sections (6), so that separate zones are formed by the first sections (5), which are not connected to each other.

8. Method for producing an adhesive bond between at least two joining partners (11, 12), comprising the steps of: - providing a film adhesive (1) according to any one of claims 1 to 4, - contacting the film adhesive (1) with a respective joining surface of the first and at least the second joining partner (11, 12) and - curing of the adhesive (4) of the film adhesive (1).

9. Method according to claim 8, characterized in that the joining partners (11, 12) are fiber composite components which are produced from a fiber composite material comprising a fiber material and a matrix material.