FR2864972A1 - Reinforcing material for resin-based composition components comprises filaments or fibres in one or more parallel planes connected by stitching or knitting - Google Patents

Abstract

The reinforcing material (1) consists of an assembly (2) of filaments or fibres connected by stitching (3) or knitting, and includes a series of filaments (4) able to exercise a stiffening function, possibly after treatment, distributed in one or more planes parallel to the main faces of the composition component in which they are embedded. The filaments have a preferable stiffness of between 2.5 and 4.5 mg, and are made from associated fibrous and thermoplastic materials, pre-impregnated or powdered with a thermo-setting resin, or from metal or synthetic monofilaments. The reinforcing material can also contain two mats (51, 52) separated by a layer (6) of non-woven fibres, preferably thick, lightweight and aerated, such as Rovicore (RTM), Core Glass (RTM) or Rovimat (RTM), produced by Chomarat Composites. Reinforcing filaments can be of Diagonap (RTM) and Roviply (RTM) made by the same company.

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 producing said product. It is thus known to use reinforcing reinforcements in connection with cement, concrete, plastics and resins.

  The composite materials and composite parts are essentially composed of an organic matrix, most often a thermoplastic or thermoset resin, and an armature or reinforcing complex.

  There are different types of reinforcement reinforcement. Beside woven reinforcement widths of greater or lesser width, a number of reinforcing complexes whose reinforcing function is exerted by a set of threads and / or stitch bonded / knitted reinforcing fibers have been developed.

  Among them, mention may be made of 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 interlacing.

  Mention may also be made of fibrous complexes based on short fiber poles or long fibers, optionally combined with a nonwoven fabric. For this purpose, reference may be made to the range of ROVICORE reinforcement complexes marketed by the company CHOMARAT COMPOSITES, these products being in particular described in the patents published under the numbers FR 2 646 442, FR 2 722 802 and incidentally FR 2 726 297. and the range of CORE GLASS reinforcing complexes, also marketed by the company CHOMARAT COMPOSITES and in particular described in the patent published under the number FR 2 734 847.

  The yarns and / or fibers providing the reinforcing function of the reinforcing complex are bound by seams in line or in zigzag thanks to the so-called stitching / knitting technique 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 reinforcing complexes of the prior art is that, during the manufacture of a subsequent composite part, the resin is often injected at such a pressure, that there is a risk of driving the yarns and / or reinforcement in inter-seam areas. This results in deviations of said son and / or reinforcing fibers, which can cause a weakening of the reinforcing function, or the presence of folds that 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, described above, which makes it possible to overcome these disadvantages.

  The reinforcing complexes according to the invention are in the form of a plate with a coherent and semi-rigid character. By coherent nature, it should be considered that the complex according to the invention is designed to have a clean behavior and to be able to withstand certain handling constraints, or even implementation for obtaining a semi product -finished later.

  To achieve this objective, the reinforcing complex according to the invention, intended for the formation of composite parts based on thermoplastic or thermosetting resin injected, in which the reinforcing function is mainly exerted by a set of son or reinforcing fibers bonded by sewing / knitting, further comprises a series of son capable of exerting a stiffener function, possibly after treatment, distributed in one or more planes parallel to the large faces of the reinforcement complex, so as to extend, in each of these said plans, parallel to each other while being spaced from each other.

  Stiffening son means son whose function is to strengthen the strength of the complex and minimize the risk of chasing the son / and or reinforcing fibers in the areas between the seams, during the injection of the resin during the manufacture of subsequent composite parts.

  Various other characteristics appear from the description given below with reference to the accompanying drawings which show, in schematic form and by way of non-limiting examples, embodiments of the subject of the invention.

  Fig. 1 is a schematic view, in cross section, of a reinforcing complex according to the invention.

  Fig. 2 is a partial perspective view illustrating another embodiment, with tearing, so as to highlight the various constituent webs.

  As illustrated in fig. 1, the reinforcing complex 1 consists mainly of a set 2 assuming the reinforcing function. The fibers and / or reinforcing threads of this set are bonded by sewing / knitting 3. This set 2 can be organized in one or more layers or layers. This set 2 confers on the complex 1 an almost total coverage, tending substantially towards 100%, that is to say that it is not perforated on all its surface, with the exception of the sewing zones which often causes a slight deviation of 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 areas between the seams.

  By son stiffeners 4 is meant, in particular, son which have a stiffness of between 1 and 5 mg, preferably between 2.5 and 4.5 mg. This stiffness is measured with a device of measurement of the rigidity (in English Bending Resistance / Stiffness test) the Teledyne Gurley of the company GURLEY PRECISION INSTRUMENTS. Measurements are made on a 4.6 cm long wire positioned in the second hole of the unit from the bottom, with the following settings on the unit being used: length: 1 ", width: 2", weight position 4 ", weigth: 200.

  These stiffener son 4 are, for example, made of a fibrous material and a thermoplastic material. They correspond in fact to reinforcing son having previously undergone a dressing step with a thermoplastic material. The thermoplastic material is advantageously 5 to 60% by weight of the stiffener wire. In some cases, the thermoplastic material used may have the characteristic of dissolving in the subsequently injected resin such as, for example, PVAC dissolves in polyester or vinylester resins. The initial stiffener function wire is then transformed into reinforcement thread within the final composite part and thus contributes after its impregnation to the overall performance of the part.

  The stiffening yarns 4 are, for example, reinforcing filaments joined with thermoplastic filaments, yarns composed of a fibrous core coated with a thermoplastic material, or yarns composed of a fibrous core covered at least partially with a thermoplastic powder.

  The stiffening son may also be in the form of reinforcement son prepreg or powdered with a thermoset resin, such as epoxy, phenolic or polyester in particular, representing from 1 to 60% by weight of the stiffener wire.

  According to another variant, metal stiffening son or single-strand synthetic son may be used.

  According to an alternative embodiment, the reinforcing complex 1 according to the invention may contain, not stiffening son present in their final state, but son son precursors stiffeners. In this case, the present wire becomes, after treatment, a wire with the desired stiffness. Indeed, in the case where the stiffening son find their stiffness in the presence of a thermoplastic or thermoset resin which constitutes them, it is possible that these son are present within the reinforcing complex: either in the form of son whose material thermoplastic or thermoset is already in a polymerized or crosslinked state giving them the desired stiffness, either still flexible son, for example in the form of reinforcement son powdered with a thermoplastic or thermosetting resin, or reinforcing son comélés with resin son thermoplastic, the connection between the reinforcing son and the resin is not yet realized.

  These son are then named precursors son reinforcement son.

  In this case, during the heating step used for the production of a composite part, either a stiffening / polymerization of the resin occurs in the case of a thermoplastic resin, or a crosslinking in the case of a thermoplastic resin. a thermosetting resin, accompanied by the impregnation of the reinforcement wire constituting the stiffening wire.

  In the rest of the text, the term son stiffeners will also include the son son precursors stiffeners.

  Sewing / knitting, linking the complex, can be done online or zigzag. The axis of a seam is chosen to extend parallel to a portion of the threads bonded by said seam. In particular, the stiffening wires extend, advantageously, parallel to the axis of the seam that binds them. A gauge between 2 and 12 threads / 25.4 mm and a stitch length of between 2 and 11 mm is preferably used. As the knitting stitching yarn which makes it possible to bind the various elements of the reinforcing complex, it will be preferable to use relatively fine synthetic yarns advantageously 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 reinforcing complex, draining threads parallel to each other and to the stiffening wires 4.

  These draining son have a diffuser function for the resin subsequently injected during the manufacture of composite parts. Draining son means reinforcing son provided with an accessory facilitating drainage of a resin injected into the reinforcing complex according to the invention. The insertion of the draining son is advantageous because, in the case of reinforcement complexes according to the invention having an almost total coverage, that is to say in the case of non-open complexes, problems of availability for the injected resin during the manufacture of molded parts, can arise. However, the drainage wire accessory provides space around the latter, which area will serve as a passage for the resin during its diffusion within the reinforcing complex.

  Different types of draining son, allowing the formation of passages facilitating the circulation of the resin subsequently injected into the reinforcing complex 1, may be used.

  According to a first exemplary embodiment, the draining son are in the form of reinforcements, preferably glass fibers, dressed with fibers of sufficient capillarity to drain the injected resin. The fibers acting as an accessory of the reinforcement yarn used may, for example, be hydrophilic cotton fibers or cellulosic fibers, or else fibers made of polypropylene, polyester or polyethylene terephthalate. These fibers have a title advantageously between 0.1 and 17 decitex. The weight deposited of these fibers around the reinforcing thread is, for example, between 5 and 50 g per 100 linear meters. The single reinforcement thread has, for example, a title of 1 200 tex and 1350 tex after dressing with the draining fibers. In this case, the draining son used can be called hairy son.

  According to a second exemplary embodiment, the draining son are in the form of gimped son, that is to say reinforcing son on each of which a monofilament comes to wind. The monofilament is, advantageously, 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 thread is, for example, between 1 and 50 g for 100 linear meters. As for the assembly twist, it is advantageously between 20 and 200 revolutions per linear meter.

  According to another variant, it may be envisaged to use, as draining wire, two reinforcing son, juxtaposed by dusting with a thermoplastic or thermosetting powder compatible with the resin subsequently injected. These two son are very different titration, the title of the smallest can tend to zero. By way of example, a reinforcing thread of 1200 tex glued to another reinforcing thread of 68 tex, thanks to a thermoplastic powder, can act as a creep network.

  Like the stiffening son 4, the draining son are spaced apart, within the reinforcing complex. This distribution is preferably regular and the spacing pitch existing between the two draining son is advantageously between 10 and 500 mm.

  Preferably, a draining wire will be chosen between two stiffening wires 4. Advantageously, the draining wires will be spaced at the same pitch as the stiffening wires 4 but offset by half a step with respect to the latter.

  Just like the set 2 and the stiffener threads 4, the draining threads are bonded within the reinforcement complex 1, thanks to the knitting stitch 3.

  The assembly 2 providing the reinforcing function may be mono- or multilayer, ie consisting of a single or an association of fibrous structures with reinforcing function.

  It may consist of a mat of long or short fibers. By short fibers is meant cut fibers, a length of between 1 and 10 cm. Advantageously, these fibers will be glass, carbon, aramid and will have a titer of between 5 and 200 dtex. Advantageously, as illustrated in FIG. 1, the assembly 2 will comprise two mats 51 and 52 of fibers, these mats being spaced apart by a nonwoven 6, preferably light, thick and airy as described in FR 2 646 442. The son stiffeners 4 will be inserted between the mat 51 and non-woven 6. It could just as well be expected to insert them within the non-woven or one of the mats or surface of the assembly 2.

  As a set 2 based on fiber mat, mention may be made of the reinforcements of the ROVICORE, CORE GLASS and ROVIMAT ranges marketed by the company CHOMARAT COMPOSITES.

  The assembly 2 may also consist of a single sheet of reinforcing son extending parallel to each other. In this case, the stiffening son 4 are distributed within this layer. The reinforcement assembly 2 may also be bi-sorted or tri-directional and may comprise from 2 to 4 plies of reinforcing threads extending parallel to each other in each of the plies, the plies being superposed without interlacing. The threads of the different plies intersect at angles, for example 90 or 45. As a set 2 based on parallel son plies, mention may be made of the reinforcements of the DIAGONAP range and the ROVIPLY range marketed by the company CHOMARAT COMPOSITES. FIG. 2 illustrates an exemplary embodiment: the assembly 2 consists of a first ply of reinforcing threads 71 parallel to each other, of a second ply of reinforcing threads 72 parallel to one another, superimposed without interlace on the threads 71 of the first ply so as to form with them an angle of 45 and a third ply of reinforcement son 73 parallel to each other, superimposed without interlace on the son 72 of the second ply so as to form with them a angle of 90 and an angle of 45 with those of the first web. Stiffening son 4 are inserted within the second layer and extend parallel to the son 72 constituting the latter. As illustrated in FIG. 2, it may be provided to integrate stiffening wires 4 in the other two layers.

  The reinforcing threads of these plies may be in a material selected from the following: glass, basalt, carbon, aramid, high performance synthetic. These reinforcing son advantageously have a titer of between 20 and 1000 tex for the aramid yarns, between 68 and 960 tex for the glass or basalt yarns and between 68 and 6,000 tex for the carbon yarns. These son may be in the form of single-strand circular cross section or the like, monobrins flat or in a multifilamentary form, spread or not, in the manner of a wick or organized for the filaments extend parallel to each other. Preferably, the reinforcing son are multifilamentary. The reinforcing threads can be with or without torsion. Advantageously, the reinforcing threads may also be voluminized or textured and will then play an additional reserve function for the thermoplastic or thermosetting material or resin which will subsequently be injected.

  The assembly 2 may also combine sheets of parallel reinforcement son and / or non-woven and / or matte long or short fibers.

  The reinforcing complex according to the invention may also comprise other elements such as an appearance veil, associated for example by gluing.

  The complex 1 according to the invention is in the general form of a plate and is therefore of substantially constant thickness. The stiffener wires 4 extend parallel to the large faces of the reinforcing complex 1. The stiffening wires may 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. Fig. 2). In each of these planes, the stiffening wires extend parallel to one another. The direction given to the stiffener wires 4 is chosen according to how the complex will be implemented. When the complex 1 is intended. the production of small composite parts during which the resin is injected into the complex in a direction parallel to the large faces of the reinforcing complex 1, the stiffening son 4 are oriented parallel to the preferred direction for the injection of the resin. In the case of the production of composite parts of great length, the resin is generally injected perpendicularly to the large faces of the reinforcing complex 1. In this case, the choice of the orientation of the stiffening son is less important. In the case of 1 thick reinforcement complexes, consisting of several layers or fibrous webs, different sets of stiffening son may be integrated within or between the various fibrous reinforcement plies 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 that may be different from one shot to another. As illustrated in FIG. 2, in the case of reinforcing 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 to which they are integrated. .

  The stiffening wires are distributed spaced apart, within the reinforcing complex and 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 existing between two stiffening son of the same plane is advantageously between 5 and 50 cm. The stiffener wires 4 represent less than 10% of the total weight of the reinforcement complex 1.

  The connection of the stiffening wires with the entire reinforcing complex is also performed by sewing / knitting. Each stiffening wire is thus caught in at least one seam.

  The reinforcing complexes according to the invention are manufactured according to conventional techniques, well known to those skilled in the textile industry. A conventional knitting stitch is used. The nonwovens are, for example, previously made by carding. The short fiber mats can be produced in a continuous process by fiber cutting, followed by a conventional dry lay, the parallel reinforcement son plies using cylinders in the direction of production and possibly framing carriages. .

  Thus, the product 1 according to the invention can be obtained simply and cleanly. Such a product 1 is also easily storable, manipulable and its cutting is easy. The product according to the invention is perfectly adapted to serve as reinforcing reinforcement for resins or bitumens. Such a product is nevertheless characterized by an elastic deformation faculty, possibly making it rollable.

  Furthermore, the presence of the stiffening son 4 within the complex 1 minimizes the risk of spacing between the reinforcing son, during the injection of resin during the manufacture of composite parts. This minimizes the presence in the room of embrittlement zones consisting solely of resin without fibrous reinforcement and improves the homogeneity of the material obtained.

  The reinforcing complexes according to the invention, and in particular those based on layers of parallel reinforcing threads, may be used, for the manufacture of non-deformable or little deformable composite parts, advantageously by infusion or injection of thermoplastic or thermosetting resin, especially for the manufacture of blades of wind turbines or parts of boats.

  The reinforcing complexes according to the invention, and in particular those based on fibrous mat, may be used for the manufacture of deformable composite parts, including industrial parts, parts of boats or automobiles. These parts will advantageously be manufactured by low pressure pressing with resin injection (RTM) thermoplastic or thermosetting. The reinforcing complexes according to the invention, and in particular those based on fibrous mat, may 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 (18)

CLAIMS:   1 - Strengthening complex (1), for the formation of composite parts based on thermoplastic or thermosetting resin injected, having a substantially constant thickness, the reinforcing function being mainly exerted by a set (2) of yarns and / or fibers of reinforcement linked by stitching / knitting (3) characterized in that it comprises a series of son (4) capable of exerting a stiffener function, possibly after 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.   2 - reinforcing complex (1) according to claim 1, characterized in that the son (4) capable of exerting a stiffener function have a stiffness of between 1 and 5 mg, preferably between 2.5 and 4.5 mg .   3 - reinforcing complex (1) according to claim 1 or 2, characterized in that the stiffening son (4) are son associating a fibrous material and a thermoplastic material, son prepreg or powdered with a thermoset resin, metal son or single-strand synthetic threads.   4 - reinforcing 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 comélés with thermoplastic son, yarns composed of a fibrous emulsion coated with a thermoplastic material, or son composed of a fibrous core at least partially covered with a thermoplastic powder.   - Reinforcement complex (1) according to one of claims 1 to 4, characterized in that draining son are distributed spaced apart within the reinforcing complex (1) and extend between the stiffening son (4). ) parallel to these.   6 - reinforcing complex (1) according to one of claims 1 to 5, characterized in that the stiffening son (4) represent less than 10% of the total weight of the reinforcement complex (1).   7 - Strengthening complex (1) according to one of claims 1 to 6, characterized in that the stiffening son, in each of the planes parallel to the large faces of the complex (1) in which they are arranged, are spaced apart from each other. other, at a spacing pitch of between 5 and 50 cm.   8 - reinforcing complex (1) according to one of claims 1 to 7, characterized in that the stiffening son (4) all extend parallel to the preferred direction of injection of the thermoplastic resin and / or thermosetting.   9 - reinforcing complex (1) according to one of claims 1 to 7, characterized in that the stiffening son (4) are distributed in at least two parallel planes large faces of the complex (1) in which they extend parallel to a different direction from one plane to another.   10 - reinforcing complex (1) according to one of claims 1 to 9, characterized in that the reinforcing function is in particular exerted by a sheet of reinforcement son parallel to each other.   11 - reinforcing complex according to claim 10, characterized in that the reinforcing function is exerted by a series of two to four plies, reinforcement son extending parallel to each other in each of the plies, said plies being superimposed without interlace .   12 - reinforcing complex according to one of claims 1 to 9, characterized in that the reinforcing function is in particular exerted by a short fiber mast.   13 - Reinforcement complex according to one of claims 1 to 9, characterized in that the reinforcing function is in particular exerted by a long fiber mast.   14 - reinforcing complex according to claim 12 or 13, characterized in that the reinforcing function is mainly exerted by a set of two long and / or short fiber mats spaced apart by a nonwoven.   - Use of a reinforcing complex according to claim 10 or 11 for producing, by infusion or injection of thermoplastic or thermosetting resin, non-deformable or little deformable composite parts.   16 - Use of a reinforcing complex according to one of claims 12 to 14 for producing, by infusion or injection of thermoplastic or thermosetting resin, deformable composite parts.   17 - Use of a reinforcing 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 parts of boats.   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.   - Use of a reinforcing 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 resin injection (RTM) thermoplastic or thermosetting.   21 - Use according to claim 19 or 20, for the manufacture of industrial parts, parts of boats or automobiles.