WO2005072940A1

WO2005072940A1 - Novel reinforcing stiffening wire complex

Info

Publication number: WO2005072940A1
Application number: PCT/FR2005/000082
Authority: WO
Inventors: Jacques Baudonnel
Original assignee: Chomarat Composites
Priority date: 2004-01-14
Filing date: 2005-01-14
Publication date: 2005-08-11
Also published as: FR2864972A1; FR2864972B1

Abstract

The invention relates to a reinforcing complex (1) for forming composite parts based on injected thermoplastic or thermosetting resins, wherein the reinforcing function is mainly carried out by a wire assembly (2) and/or reinforcing fibres bound by sewing/knitting (3). The inventive complex is characterised in that it comprises a range of wires (4) which fulfil a stiffening function, possibly after a heat treatment, and are distributed on one or several planes which are parallel to the large surfaces of the reinforcing complex in such a way that they extend on each plane in a parallel direction to each other being spaced from each other.

Description

The present invention relates to the field of reinforcement products intended to constitute reinforcements within composite parts. In many fields, it is desirable to be able to reinforce a manufactured product, so as to increase certain mechanical characteristics conferred by the constituent material used for the production of said product. It is thus known to use reinforcing reinforcements in connection with cement, concrete, plastics and resins. Composite materials and composite parts are essentially composed of an organic matrix, most often a thermoplastic or thermoset resin, and a reinforcement or reinforcement complex. There are different types of reinforcement. In addition to the woven reinforcements of more or less wide widths, a certain number of reinforcement complexes whose reinforcement function is exerted by a set of reinforcing threads and / or fibers linked by sewing / knitting have been developed. Among them, one can cite the unidirectional, bidirectional, three-dimensional, or even four-dimensional reinforcement complexes composed of one to four plies of reinforcing threads parallel to each other in each of the plies, the plies being superimposed on each other without interleaving. Mention may also be made of fibrous complexes based on a mast of short fibers or of long fibers, optionally combined with a nonwoven. For this purpose, reference may be made to the RONICO building complex range? RE ^® marketed by CHOMARAT COMPOSITES, these products are described in particular in patents published under the numbers FR 2,646,442, FR 2,722,802 and incidentally EN 2,726,297 and CORE GLASS building complexes range ^®, also sold by the company CHOMARAT COMPOSITES and described especially in the patent published under number FR 2 734 847. the son and / or fibers for the reinforcement of the complex function reinforcement are linked by in-line or zigzag stitching using the technique known as "sewing / knitting" with reference to the French patents published under the numbers FR 1 469 065, FR 1 095 507 and FR 2 048 071. A disadvantage of the reinforcement complexes of the prior art is that, during the manufacture of a subsequent composite part, the resin is often injected at such pressure, that there are risks of chasing the yarns and / or fibers from reinforcement in the inter-seam areas. This results in deviations of said son and / or reinforcing fibers, which can cause a weakening of the reinforcing function, or even, the presence of folds which cause embrittlement of the composite part obtained. In this context, the object of the invention is to propose an improvement to the reinforcement complexes of the prior art, previously described, which makes it possible to overcome these drawbacks. The reinforcement complexes according to the invention are in the form of a plate with a coherent and semi-rigid character. By consistency, it should be considered that the complex according to the invention is produced so as to have a clean hold and to be able to withstand certain handling constraints, or even implementation for obtaining a semi product. -finished later. To achieve this objective, the reinforcement complex according to the invention, intended for the formation of composite parts based on injected thermoplastic or thermosetting resin, in which the reinforcement function is mainly exercised by a set of reinforcing wires or fibers linked by sewing / knitting, further comprises a series of threads capable of exerting a stiffening function, possibly after heat treatment, distributed in one or more planes parallel to the large faces of the reinforcement complex, so as to extend, in each of said planes, parallel to each other while being spaced from each other. The term “stiffening threads” means threads which have the function of reinforcing the strength of the complex and minimizing the risks of chasing the reinforcing threads / and / or fibers in the areas present between the seams, during the injection of the resin during the manufacture of subsequent composite parts. Various other characteristics will emerge from the description given below with reference to the appended drawings which show, in schematic form and by way of nonlimiting examples, embodiments of the subject of the invention. The fig. 1 is a schematic view, in cross section, of a reinforcement complex according to the invention. The fig. 2 is a partial perspective view illustrating another alternative embodiment, with cutaway, so as to highlight the various constituent plies. As illustrated in fig. 1, the reinforcement complex 1 mainly consists of a set 2 assuming the reinforcement function. The fibers and / or reinforcing threads of this set are linked by sewing / knitting 3. This set 2 can be organized in one or more layers or layers. This assembly 2 gives the complex 1 almost total coverage, tending substantially towards 100%, that is to say that it is not openwork over its entire surface, with the exception of the sewing zones which very often results in a slight deviation of the son. According to one of its essential characteristics, the complex according to the invention comprises stiffening wires 4, intended to reinforce the strength and the cohesion of the fibrous complex, in order to avoid that, during the subsequent injection of a resin, the reinforcing threads and / or reinforcing fibers do not deviate too much from each other, in the zones located between the seams. By stiffening threads 4 is meant, in particular, threads which have a stiffness of between 1 and 5 mg, preferably between 2.5 and 4.5 mg. This stiffness is measured with a rigidity measuring device (in English "Bending Resistance / Stiffness tester") the "Teledyne Gurley" from the company GURLEY PRECISION INSTRUMENTS. The measurements are taken on a 4.6 cm long wire positioned at the second hole of the device from the bottom, the following settings on the device being used: length: 1 ", width: 2", weight position 4 ", weigth: 200. These stiffening wires 4 are, for example, made of a fibrous material and of a thermoplastic material. They actually correspond to reinforcing wires having previously undergone a covering step with a thermoplastic material. The thermoplastic material advantageously represents 5 to 60% by weight of the stiffening wire In some cases, the thermoplastic material used can have the characteristic of dissolving in the resin subsequently injected, for example, PNAC dissolves in polyester resins or vinylester. The wire with initial stiffener function then becomes a reinforcement wire within the part composite final and thus contributes after its impregnation to the overall performance of the part. The stiffening threads 4 are, for example, reinforcing filaments comelé with thermoplastic filaments, threads composed of a fibrous core coated with a thermoplastic material, or else threads composed of a fibrous core covered at least partially with a thermoplastic powder. The stiffening threads can also be in the form of reinforcing threads prepreg or powdered with a thermoset resin, of the epoxy, phenolic or polyester type in particular, representing from 1 to 60% of the weight of the stiffening thread. According to another variant, metallic stiffening threads, or single-strand synthetic threads, may be used. According to an alternative embodiment, the reinforcement complex 1 according to the invention may contain, not stiffening threads present in their final state, but precursor threads of stiffening threads. In this case, the wire present becomes, after treatment, a wire endowed with the desired stiffness. Indeed, in the case where the stiffening wires find their stiffness in the presence of a thermoplastic or thermoset resin which constitutes them, it is possible that these wires are present within the reinforcement complex: - either in the form of wires whose thermoplastic or thermoset material is already in a polymerized or crosslinked state giving them the desired stiffness, either still flexible son, for example in the form of reinforcing son powdered with a thermoplastic or thermosetting resin, or reinforcing son comelés with son thermoplastic resin, the connection between the reinforcing threads and the resin not yet produced. These threads are then called precursor threads of reinforcing threads. In this case, during the heating step implemented for the production of a composite part, there is either stiffening / polymerization of the resin in the case of a thermoplastic resin, or crosslinking in the case of '' a thermosetting resin, accompanied by the impregnation of the reinforcing wire constituting the stiffening wire. In the remainder of the text, the term “stiffening threads” will also include the precursor threads of stiffening threads. Sewing / knitting, ensuring the connection of the complex, can be done in line or in a zigzag. The axis of a seam is chosen so as to extend parallel to a part of the threads linked by said seam. In particular, the stiffening wires advantageously extend parallel to the axis of the seam which links them. Preferably, a gauge between 2 and 12 threads / 25.4 mm and a stitch length between 2 and 11 mm are used. As knitting sewing thread used to link the different elements of the reinforcement complex, use will be made of relatively fine synthetic yarns, advantageously with a count of between 100 and 300 dtex (167 dtex for example), for example polyester yarns. According to a variant of the invention, not shown, it is also possible to include, within the reinforcement complex of the draining wires, which are parallel to each other and to the stiffening wires 4. These draining wires have a function of diffuser for the resin subsequently injected during the production of composite parts. By draining threads is meant reinforcing threads provided with an accessory facilitating the drainage of a resin injected into the reinforcement complex according to the invention. The insertion of the draining wires is advantageous because, in the case of reinforcement complexes according to the invention having almost total coverage, that is to say in the case of non-perforated complexes, availability problems for the resin injected , during the production of molded parts, can arise. However, the accessory of the draining wire provides a space around the latter, a space which will serve as a passage for the resin during its diffusion within the reinforcement complex. Different types of draining son, allowing the formation of passages facilitating the circulation of the resin subsequently injected into the reinforcement complex 1, can be used. According to a first embodiment, the draining wires are in the form of reinforcements, advantageously made of glass fibers, covered with fibers of sufficient capillarity to drain the injected resin. The fibers, acting as an accessory to the reinforcing thread used, can, for example, be hydrophilic cotton fibers or cellulosic fibers or, alternatively, fibers of polypropylene, polyester or polyethylene terephthalate. These fibers have a titer advantageously between 0.1 and 17 decitex. The weight deposited of these fibers around the reinforcing wire is, for example, between 5 and 50 g per 100 linear meters. The reinforcing wire alone has, for example, a titer of 1,200 tex and 1,350 tex after covering with the draining fibers. In this case, the draining threads used can be qualified as hairy threads. According to a second embodiment, the draining threads are in the form of wrapped threads, that is to say reinforcing threads on each of which a monofilament comes to be wound. The monofilament is advantageously made of polyamide, polyethylene terephthalate, polypropylene or metal. The diameter of this monofilament is preferably between 0.1 and 2 mm. The weight deposited of this monofilament around the reinforcing wire is, for example, between 1 and 50 g per 100 linear meters. The assembly twist, for its part, is advantageously between 20 and 200 turns per linear meter. According to another variant, it can be envisaged to use, as a draining wire, two reinforcing wires, juxtaposed by dusting with a thermoplastic or thermosetting powder compatible with the resin subsequently injected. These two wires have very different titrations, the title of the smallest being able to reach zero. For example, a 1,200 tex reinforcing wire bonded to another 68 tex reinforcing wire, using a thermoplastic powder, could play the role of creep network. Like the stiffening wires 4, the draining wires are spaced apart within the reinforcement complex. This distribution is preferably regular and the spacing pitch, existing between the two draining wires, is advantageously between 10 and 500 mm. We will preferably choose to have a draining wire between two stiffening wires 4. Advantageously, the draining wires will be spaced at the same pitch as the stiffening wires 4 but offset by a half-step with respect to the latter. Just like the assembly 2 and the stiffening wires 4 the draining wires are linked within the reinforcement complex 1, thanks to the knitting stitching 3. The assembly 2 ensuring the reinforcement function can be mono- or multi-layers, c 'is to say made up of a single or an association of fibrous structures with a reinforcing function. It can consist of a mat of long or short fibers. By short fibers is meant cut fibers, with a length of between 1 and 10 cm. Advantageously, these fibers will be made of glass, carbon, aramid and will have a titer between 5 and 200 dtex. Advantageously, as illustrated in FIG. 1, the assembly 2 will comprise two mats 5χ and 5 ₂ of fibers, these mats being spaced apart by a nonwoven 6, preferably light, thick and airy as described in FR 2 646 442. The stiffening wires 4 will be inserted between the mat 5ι and the nonwoven 6. It could just as easily be provided for inserting them within the nonwoven or one of the mats or on the surface of the assembly 2. In 2 as a set-based fiber mat include reinforcements ranges RONICORE ^® cORE GLASS ^® and RONIMAT ^® marketed by CHOMARAT COMPOSITES. The assembly 2 can also consist of a single ply of reinforcing threads extending parallel to each other. In this case, the stiffening wires 4 are distributed within this ply. The reinforcement assembly 2 can also be bi, tri or four-way and include from 2 to 4 plies of reinforcing threads extending parallel to each other in each of the plies, the plies being superimposed without interleaving. The threads of the different layers cross at angles, for example 90 or 45 °. As a set 2 based parallel son slicks include reinforcements of DIAGO AP ^® range and range ROVIPLY ^® marketed by CHOMARAT COMPOSITES. Fig.2 illustrates an exemplary embodiment: the assembly 2 consists of a first ply of reinforcing wires ι parallel to each other, of a second ply of reinforcing wires 7 ₂ parallel to each other, superimposed without interlacing on the wires 1 of the first ply so as to form an angle of 45 ° with them and a third ply of reinforcing wires 7 ₃ parallel to one another, superimposed without interlacing on the wires 7 ₂ of the second ply so as to form with the latter an angle of 90 ° and an angle of 45 ° with those of the first layer. Stiffening wires 4 are inserted within the second ply and extend parallel to the wires 7 ₂ constituting the latter. As illustrated in Fig. 2, provision may be made to integrate stiffening wires 4 within the other two plies. The reinforcing threads of these layers may be of a material chosen from the following: glass, basalt, carbon, aramid, high performance synthetic. These reinforcing threads advantageously have a count of between 20 and 1000 tex for the aramid threads, between 68 and 960 tex for the glass or basalt threads and between 68 and 6000 tex for the carbon threads. These yarns can be in the form of single strands of circular cross section or the like, of single strands of flat character or in a multifilament form, spread out or not, in the manner of a wick or, also organized so that the filaments extend parallel to each other. Preferably, the reinforcing threads are multifilament. The reinforcing wires can be with or without twisting. Advantageously, the reinforcing threads can also be voluminized or textured and will then play an additional reserve function for the thermoplastic or thermosetting material or resin which will be subsequently injected. The assembly 2 can also combine layers of parallel and / or non-woven and / or mat reinforcing threads of long or short fibers. The reinforcement complex according to the invention may also include other elements such as an appearance veil, associated for example by bonding. The complex 1 according to the invention is in the general form of a plate and is therefore of substantially constant thickness. The stiffening wires 4 extend parallel to the large faces of the reinforcement complex 1. The stiffening wires can all be arranged in a plane parallel to the large faces of the complex (FIG. 1) or distributed in several planes parallel to the large faces of the complex ( Fig. 2). In each of these planes, the stiffening wires extend parallel to each other. The direction given to the stiffening wires 4 is chosen according to the way in which the complex will be implemented. When the complex 1 is intended for the production of small composite parts during which the resin is injected within the complex in a direction parallel to the large faces of the reinforcement complex 1, the stiffening wires 4 are oriented parallel to the preferred direction for the resin injection. In the case of the production of long composite parts, the resin is generally injected perpendicular to the large faces of the reinforcement complex 1. In this case, the choice of the orientation of the stiffening wires is less important. In the case of 1 thick reinforcement complexes, consisting of several fibrous layers or layers, different series of stiffening threads can be integrated within or between the different fibrous reinforcement layers constituting the complex. In this case, the stiffening wires 4 are, in general, distributed in at least two planes parallel to the large faces of the complex 1. In each of these planes, they extend parallel to each other, in a direction which may be different from one plan to another. As illustrated in Fig. 2, in the case of a reinforcement complex consisting of different plies of reinforcing threads extending parallel to each other, the reinforcing threads extend parallel to the reinforcing threads of the ply in which they are integrated . The stiffening wires are distributed spacedly within the reinforcement complex and this in each of the planes parallel to the large faces of the complex in which they are arranged. This distribution is preferably regular and the spacing pitch between two stiffening wires of the same plane is advantageously between 5 and 50 cm. The stiffening wires 4 represent less than 10% of the total weight of the reinforcement complex 1. The connection of the stiffening wires with the whole of the reinforcement complex is also carried out by sewing / knitting. Each stiffening wire is therefore caught in at least one seam. The reinforcement complexes according to the invention are manufactured according to conventional techniques, well known to those skilled in the art of the textile industry. A conventional knitting sewing loom is used. The nonwovens are, for example, produced beforehand by carding. The short fiber mats can be processed in a continuous process by cutting fibers, followed by a conventional dry coating, the layers of parallel reinforcing threads using cylinders in the production direction and optionally trolleys . Thus, the product 1 according to the invention can be obtained in a simple and clean manner. Such a product 1 is also easily storable, easy to handle and its cutting is easy. The product according to the invention is perfectly suited to serve as a reinforcing reinforcement for resins or bitumens. Such a product is nevertheless characterized by an elastic deformation faculty, making it possibly rollable. Furthermore, the presence of the stiffening wires 4 within the complex 1 makes it possible to minimize the risks of separation between the reinforcing wires, during the injection of resin during the manufacture of composite parts. This minimizes the presence, in the room, of weakening zones made only of resin without fibrous reinforcement and improves the homogeneity of the material obtained. The reinforcement complexes according to the invention, and in particular those based on plies of parallel reinforcing threads, may be used, for the manufacture of non-deformable or slightly deformable composite parts, advantageously by infusion or injection of thermoplastic or thermosetting resin, especially for the manufacture of wind turbine blades or boat parts. The reinforcement complexes according to the invention, and in particular those based on fibrous mat, may be used, for the manufacture of deformable composite parts, and in particular industrial parts, boat or automobile parts. These parts will advantageously be manufactured by low pressure pressing with injection of thermoplastic or thermosetting resin (RTM). The reinforcement complexes according to the invention, and in particular those based on fibrous mat, can also be used to maintain the shape of a preform, formed intermediately, in the manufacture of a composite part. The above invention is not limited to the examples described and shown, since various modifications can be made without departing from its scope.

Claims

CLAIMS: 1 - Reinforcement complex (1), for the formation of composite parts based on injected thermoplastic or thermosetting resin, having a substantially constant thickness, the reinforcement function being mainly exercised by a set (2) of wires and / or reinforcing fibers linked by sewing / knitting (3) characterized in that it comprises a series of threads (4) capable of exerting a stiffening function, possibly after heat treatment, distributed in one or more planes parallel to the large faces of the complex reinforcement, so as to extend, in each of said planes, parallel to each other while being spaced from each other. 2 - Reinforcement complex (1) according to claim 1, characterized in that the wires (4) capable of exerting a stiffening function have, optionally after heat treatment, a stiffness of between 1 and 5 mg, preferably between 2, 5 and 4.5 mg. 3 - Reinforcement complex (1) according to claim 1 or 2, characterized in that the stiffening threads (4) are threads combining a fibrous material and a thermoplastic material, preimpregnated or powdered threads with a thermoset resin, metallic threads or synthetic single-strand yarns. 4 - Reinforcement complex (1) according to claim 3, characterized in that the stiffening son (4) are son associating a fibrous material and a thermoplastic material selected from reinforcing son comelés with thermoplastic son, son composed of 'A fibrous core coated with a thermoplastic material, or else yarns composed of a fibrous core covered at least partially with a thermoplastic powder. 5 - Reinforcement complex (1) according to one of claims 1 to 4, characterized in that the draining wires are distributed, spaced apart, within the reinforcement complex (1) and extend between the stiffening wires ( 4) parallel to these. 6 - Reinforcement complex (1) according to one of claims 1 to 5, characterized in that the stiffening wires (4) represent less than 10% of the total weight of the reinforcement complex (1). 7 - Reinforcement complex (1) according to one of claims 1 to 6, characterized in that the stiffening wires, in each of the planes parallel to the large faces of the complex (1) in which they are arranged, are spaced apart from one another others, at a spacing of between 5 and 50 cm. 8 - Reinforcement complex (1) according to one of claims 1 to 7, characterized in that the stiffening wires (4) all extend parallel to the preferred direction of injection of the thermoplastic and / or thermosetting resin. 9 - Reinforcement complex (1) according to one of claims 1 to 7, characterized in that the stiffening wires (4) are distributed in at least two planes parallel to the large faces of the complex (1) in which they extend parallel to a different direction from one plane to another. 10 - Reinforcement complex (1) according to one of claims 1 to 9, characterized in that the reinforcing function is in particular exerted by a sheet of reinforcing son parallel to each other. 11 - Reinforcement complex according to claim 10, characterized in that the reinforcement function is exerted by a series of two to four plies, of reinforcing threads extending parallel to each other in each of the plies, said plies being superimposed without interleaving . 12 - Reinforcement complex according to one of claims 1 to 9, characterized in that the reinforcement function is in particular exerted by a mast of short fibers. 13 - Reinforcement complex according to one of claims 1 to 9, characterized in that the reinforcement function is in particular exerted by a mast of long fibers. 14 - Reinforcement complex according to claim 12 or 13, characterized in that the reinforcement function is mainly exercised by a set of two mats of long and / or short fibers spaced apart by a nonwoven. 15 - Use of a reinforcing complex according to claim 10 or 11 for the production, by infusion or injection of thermoplastic or thermosetting resin, of non-deformable or slightly deformable composite parts. 16 - Use of a reinforcement complex according to one of claims 12 to 14 for the production, by infusion or injection of thermoplastic or thermosetting resin, of deformable composite parts. 17 - Use of a reinforcement complex according to one of claims 1 to 14, and in particular according to claim 10 or 11, for the manufacture of composite parts by infusion or injection of thermoplastic or thermosetting resin. 18 - Use according to claim 17 for the manufacture of wind turbine blades or boat parts. 19 - Use of a reinforcing complex according to one of claims 1 to 14, and in particular 12 to 14, to maintain the shape of a preform, formed intermediately, in the manufacture of a composite part. 20 - Use of a reinforcement complex according to one of claims 1 to 14 and in particular 12 to 14 for the manufacture of composite parts by low pressure pressing with injection of thermoplastic or thermosetting resin (RTM). 21 - Use according to claim 19 or 20, for the manufacture of industrial parts, boat or automobile parts.