FR2679931A1 - US TEXTILE REINFORCEMENT FOR THE PRODUCTION OF LAMINATE COMPLEXES AND PROCESS FOR OBTAINING SAME. - Google Patents

Abstract

Textile reinforcement usable for the production of laminated composites. It comprises three series of yarns (1a, 1b, 2) oriented differently in relation to one another, two (1a, 1b) being arranged slantwise, inversely to one another in relation to the length of the strip, and the yarns (2) of the third being, for their part, arranged parallel to the length and trapped between the yarns (1a, 1b). In this material the lengthwise yarns (2) consist at least partially of yarns exhibiting thermal adhesive properties, whose adhesive characteristics are developed after the braid is produced and make it possible to ensure the bonding of the two-directional outer layers (1a, 1b) without possibility of movement of the positioning of the yarns relative to one another.

Description

TEXTILE REINFORCEMENT USED FOR THE PRODUCTION OF

  LAMINATED PLEXES AND PROCESS FOR OBTAINING SAME

  The invention relates to an improvement made to the textile reinforcement used for the production of laminated complexes, that is to say of resin-based articles (polyester or other), armed with a structure

reinforcement textile.

  To date, as reinforcement textile reinforcement, in addition to structures consisting of woven or non woven webs

  woven, possibly combined with each other (for

  guillotining, stitching / knitting), it has also been proposed to use, in particular for the production of tubular hollow bodies of cylindrical or conical shape, of shapes of various shapes, braided sheaths (see FIG.

  FR-A-2 402 730 corresponding to US Pat. No. 4,228,207, FR-A-2,455,980, 2,462,266 or 2,510,624).

  Such braided sheaths, which are particularly suitable for the production of tubular articles, consist, in a known manner, of two series of intermeshing threads arranged obliquely with respect to the generatrix of the braid. braids, the son are generally oriented 45 relative to the generatrix This material being deformable, it is possible to play on this deformability to obtain laminated complexes of varying shapes and / or to vary the resistance either in the long-term direction 30 gitudinal either in the transverse direction So, it is

  possible to significantly improve the long-term

  by stretching the braid in the direction of the

  this causes a tightening of the tubular sheath

  and direct the wires of which it is composed in a di-

  rection that tends to get closer to the generator.

  Such braids consisting of two sets of intertwined threads are generally designated by the expression

"bidirectional braids".

  In addition to the bidirectional braids mentioned above,

  It has also been proposed to produce braids, referred to as "tridirectional braids", in the

  a third set of wires is arranged parallel to the generator and is trapped between the two sets of wires arranged at an angle. Such tridirectional braids can be used either alone,

  optionally include an inner core as described in FR-A-2 379 376.

  If, as said before, such reinforcing structures are suitable for the production of cylindrical elements (tubes, windsurf masts, tennis rackets), on the other hand, they are not suitable when it is desired to produce laminated materials 20 of thin, flat or shaped, obtained in particular according to the technique known as "pultrusion" technique which, in general, consists in making profiles continuously by extruding a thermosetting resin and by continuously incorporating a textile reinforcement and which therefore implies a significant tensioning, and consequently, requires the use of non-deformable reinforcements, property incompatible with that of a braid o by nature, the son can be easily moved relative to the others.

  As a result, to date, for the production of laminated articles obtained by pultrusion, and more particularly

  In the case of profiled articles (L, U, V), for example, textile reinforcements, unidirectional layers consisting of filament wicks are generally used.

  maintained in parallel with each other. These reinforcements make it possible to obtain

  They may have complex shapes, the thickness of which is constant and in which the textile reinforcement is perfectly positioned inside the resin. The profiles thus obtained have good resistance to

  the friction taking into account the longitudinal reinforcements, but, on the other hand, may have deficiencies in torsion resistance, especially in the case of elements having a large length.

  Now it has been found, and this is the subject of the present invention, an improvement in textile reinforcement of the tridirectional braid type, which solves all these problems and makes it possible to produce laminated articles, in particular by the technique said "pultrusion", which can have a profile (section L, U, V) complex, of great length and thin (of the order of a few millimeters), and wherein the reinforcing son are not moved the against each other when formatting and extend

  as well parallel than in relation to the length of the profile made.

  Admittedly, such articles comprising threads oriented in three directions had been proposed for a very long time (see US Pat. No. 3,446,256), but, as is apparent from this document, their realization implied obtaining the yarns interleaving together by weaving, in order to prevent the series of elementary yarns from moving relative to one another, therefore, although no indication is given in this document of the manner in which of which such articles could be made, it is clear that they require weaving machines which must be adapted

  important to be able to guide the warp and weft son according to three axes.

  The tridirectional reinforcement according to the invention can, in turn, be obtained by a simple method on conventional braiding material, without any adaptation of the latter as regards the production of the basic tridirectional braid entering in its realization, and this in a simple process that makes

also part of the invention.

  In general, the tridirectional reinforcement according to the invention is in the form of a flat strip, of very great length relative to its width, and which comprises three series of son oriented differently with respect to others, two being arranged obliquely, in opposite directions from each other, with respect to the length of the strip, and the wires of the third being themselves arranged parallel to the length, and trapped between the two series of yarns arranged at an angle, and it is characterized in that said longitudinal yarns consist at least in part of yarns having heat-sealing properties, whose adhesive characteristics are revealed after production of the braid, and make it possible to ensure

  external bi-directional layers without pos-

  ability to move the positioning of the wires

one against another.

  By virtue of such a structure, a material is thus obtained which not only has the advantages of braided textile reinforcements (orientation of the filaments obliquely with respect to the length and this, according to a determined angle, which can be easily adjusted during the production process.

  duction of the said braid), but who does not have the

  disadvantages (deformability) when it is

  hait to realize a profiled structure, the son of the unidirectional sheet being, moreover, maintained the

  flatter and as rectilinear as possible without moving

  in relation to each other, a necessary condition

  re to get a laminate complex of good quality,

  especially when it is thin.

  Moreover, such a structure makes it possible to produce materials that can be either composed of yarns of the same nature (for example wholly based on glass, carbon, boron, silica or aromatic polyamide yarns), or to produce a a combination of different reinforcing yarns, for example an alternation of glass and carbon yarns, both in the bidirectional structure and in the undirectional web. It may also be envisaged to incorporate into one or in the set of plies of the metal son25 possibly making it possible to shape the reinforcing material and / or to give it properties

  Finally, it is possible to produce a

  according to the invention comprising two layers of

  aforementioned type by simply flattening the tubular braid

  formed, or to obtain a monolayer web, wide, by cutting the tubular braid according to

  one of its generators and laying it flat.

  The invention also relates to a method for producing such a material, said method comprising

  both to form a tubular braid comprising at least two sets of intermeshed son relative to each other and arranged at an angle to the generatrix of said braided sheath, to introduce simultaneously to the

  formation of the braid, within the latter, between the skewed yarns, a series of longitudinal, parallel yarns, at least a part of which consists of yarns having thermoconductive properties, said method being characterized in that the posi-

  tioning of the son (transverse and longitudinal) relative to each other is fixed on the braiding machine by a heat treatment revealing the pro-prieties of fusible son.

  The heat treatment operation can be carried out after flattening the tubular braid, or possibly

  while maintaining in form said tubular braid 20, then, after fixing the son relative to each other, by cutting the latter according to a generator

then putting it back flat.

  The invention and the advantages it brings will however be better understood thanks to the exemplary embodiments given below by way of indication but not limitation, and which are illustrated by the two appended figures which are

  reproductions of articles produced coformally to the in-

  tion, some of the yarns of the slanted plies are not shown in certain areas for

  to show how the different filament layers

  are arranged in relation to each other.

  If we refer to the two appended figures in which the same elements are designated by the same references, the textile reinforcement according to the invention is therefore in the form of a flat strip, designated by the general reference ( 1), of very great length L with respect to its width 1 It comprises three series of yarns oriented differently with respect to the others. Two these series of yarns (1a, 1b) are arranged obliquely, in the opposite direction. The wires (2) of the third series, for their part, are arranged parallel to the length L and are trapped between the two sets of wires (la, lb). In the material according to the invention, the yarns (2) of the undirec-tional web consist at least partly of yarns having thermally bonded properties which are revealed by heat treatment. Such yarns (2) can be , pa for example, constituted by "core / sheath" type wires, the core being constituted by glass filaments, the

  sheath with a polymer-based coating, such as copolyamide.

  Such a complex structure is obtained directly on a conventional braiding machine, making it possible to produce a tubular braid comprising two series of yarns arranged at an angle (la, lb), between which are imprisoned longitudinal threads (2). The orientation of the arranged yarns at an angle, is obtained by setting, in a known manner, the braiding angle. The braiding angle can be either fixed, which makes it possible to obtain an article

  width 1 determined, possibly to be va-

  during production, making it possible to obtain

braid of variable section.

  In the example illustrated in FIG. 1, the tubular braid is subjected to a pressure at the outlet of the machine so that it collapses, the heat treatment making it possible to reveal the heat-sealing properties of the wires. longitudinals being realized, either during this flattening phase or after it, which allows to bind the different layers of the complex between them. In the embodiment illustrated in FIG. 2, the heat treatment revealing the properties of the heat-bonding threads of the unidirectional sheet is achieved

  by keeping the braid in its circular form, which then makes it possible to cut it into a generator to put it back flat and obtain an article of greater width.

  In the two embodiments illustrated in FIGS. 1 and 2, the material according to the invention is produced on a plastic braiding machine, of the "SPIRALTEX" type, comprising 96 spindles and thus making it possible to produce a bidirectional braid having two oriented plies. in the opposite direction, and each consisting of 48 son son (2) of the unidirectional web are incorporated in the braid in a known manner.

  In both embodiments, the plies forming the yarns arranged at an angle (1a, 1b) are constituted

  In the example illustrated in FIG. 1, the unidirectional ply (yarn 2) is constituted by yarns of the core / sheath type, the core being based on 22 tex glass yarn and the sheath consisting of a copolyamide coating having a melting point of about 115 ° C. In the example illustrated in FIG. 2, the material comprises on the one hand, fusible wires (2) of the aforementioned type used as a longitudinal element and,

  on the other hand arranged in parallel to these fusible son son (2 a), consisting of carbon locks.

  The complexes thus produced can be used in many applications, such as, for example

  as reinforcements of profiles obtained by pultrusion.

  Of course, the invention is not limited to the embodiments described above, but it covers all variants made in the same spirit.

Claims (4)

  Textile reinforcement that can be used for producing laminated complexes, which is in the form of a flat strip, very long in relation to its width, and which comprises three sets of yarns (la, lb, 2) oriented differently one against the others, two (1a, 1b) being arranged obliquely, in opposite directions to each other, with respect to the length of the strip, and the wires (2) of the third being in turn arranged parallel to the length, and trapped between the two sets of yarns (la, lb) arranged obliquely, characterized in that said longitudinal yarns (2) consist at least partly of yarns having heat-sealing properties, whose adhesive characteristics are revealed after completion of the braid,   and make it possible to ensure the connection of the bidirectional outer layers (1a, 1b) without the possibility of moving the positioning of the wires relative to each other.   2 / Textile reinforcement according to claim 1, characterized in that it comprises two layers consisting of   three-way webs, said material being obtained by flattening the tubular braid.   3 / Armature according to claim 1, characterized in that it consists of a layer of a three-way web obtained by cutting the tubu-30 braid by one of its generators and laying it flat.   4 / A method for obtaining a material according to one of claims 1 to 3, which consists in forming a   tubular braid comprising at least two sets of threads (la, lb) intertwined with each other, and arranged at an angle to the generatrix of the braided sheath, to simultaneously introduce the formation of the braid, to the the interior of the latter, between the wires (lalb) disposed at an angle, a series of longitudinal longitudinal threads (2), at least a part of which consists of threads having thermocoating properties, characterized in that the wire positioning   (transverse and longitudinal) relative to each other is fixed on the braiding machine by   The process according to claim 1, wherein the heat treatment is carried out after   The tubular braid is flattened, the resulting material thus having two superimposed tridirectional layers joined along their lateral edges.   Process according to Claim 4, characterized in that the heat treatment is carried out while maintaining   the tubular braid shaped, then, after fixing son 20 relative to each other, to cut said braid along a generator and put it back flat.