FR2766071A1 - PROCESS FOR THE MANUFACTURE OF A COMPOSITE MATERIAL FOR ANTI-VANDALISM PROTECTION, PARTICULARLY FOR SEATS, AND COMPOSITE MATERIAL OBTAINED - Google Patents

Abstract

The process for manufacturing a composite material for anti-vandalism protection, in particular for seats, consists in producing a set of three superimposed layers, the intermediate layer of which is a metal anti-vandalism grid and in joining said three layers. outer (3) being a nonwoven (2), the three layers (3, 5, 7) are joined by a simple needling strikes from barbed needles with rounded ends, so that, after needling, the face the outer layer of the first layer is free of metallic threads coming from the second layer, and that the outer face of the third layer has a limited or even zero number of metallic threads coming from the second layer. Needling is carried out using '' needles with a barbed depth less than half the diameter of each of the wires making up the metal grid and more than half the diameter of all or more part of the constituent fibers of the first layer.

Description

PROCESS FOR MANUFACTURING A COMPOSITE MATERIAL FOR THE

  ANTI-VANDALISM PROTECTION, ESPECIALLY FOR SEATS, AND

COMPOSITE MATERIAL OBTAINED

  The present invention relates to anti-vandalism protection in particular of seats intended to be placed in public places, in particular in urban transport vehicles. It relates more particularly to a composite material capable of entering into the composition of such a seat, comprising as a means of anti-vandalism protection a metal grid. It also relates to a composite material

obtained by the above method.

  Is known, in particular from document FR.2.576.200, an anti-vandal coating for seats which comprises at least three distinct superposed layers, namely a first visible outer coating layer formed of a thin material, a second 15-15 vandalism consisting of a knitted fabric of thin steel wires and a third protective layer or sublayer formed from a flexible thin material. These three superimposed layers are joined together, to form a flexible composite coating, by bonding using a flexible adhesive interposed between the first and the

  third layers. In a particular embodiment, the sub-

  protective layer has fire-resistant properties and comprises at least one non-woven layer obtained by needling of fire-resistant artificial fibers. Preferably this third layer comprises two needled nonwoven plies between which is interposed a grid of woven glass threads. These three components being assembled together

  by additional needling.

  It is the tight-knit metallic knit which, while remaining deformable, can resist laceration and which therefore protects the other layers of the covering, in particular the foam cushion or the padding which constitutes the lower part of the seat, covered by the

  three-layer coating of document FR.2.576.200.

  According to the applicant, the aforementioned coating has the drawback of using an adhesive interposed between the first and third layers to obtain the joining of the coating. The presence of such an adhesive can be troublesome, in particular when the coating must have fire-resistant properties, in addition to anti-vandalism properties,

  due to the release of smoke due to the adhesive.

  It has already been proposed to overcome this drawback in document GB.2.246. 097, by tying the three layers by sewing, according to the wadding technique, with individual sewing heads making it possible to make sewing rows separated by a distance

from 2 to 5cm.

  According to the applicant, the disadvantage of this technique is that it uses an additional sewing thread and also

  the obligation to have a wadding type installation.

  The aim set by the applicant is to propose a process for manufacturing a composite material for anti-vandalism protection, in particular for seats, which in a manner known by the two aforementioned documents consists in producing a set of three superimposed layers the intermediate layer of which is a vandal-proof metal grid and

  to join said three layers.

  Characteristically according to the invention, the first outer layer being a nonwoven, the method consists in joining the three layers by simple needling strikes from barbed needles, with rounded ends, so that, after needling, the outer face of the first layer is free of metallic threads coming from the second layer and that the outer face of the third layer has a limited or even zero number of metallic threads coming from the

second layer.

  Admittedly, the needling technique is a conventional technique for bonding several layers. For example in the document

  FR.2.576.200, the protective underlay is composed of two non-

  woven between which is interposed a woven glass grid, the whole

  being bonded by needling. These are the constituent fibers of non-tablecloths

  woven which are moved by the needles of the needling machine, which interpenetrate the different layers and thereby achieve the binding of the whole. If a needle moves a wire constituting the intermediate woven glass grid, the movement of the latter does not present any inconvenience due to the homogeneity of the various constituents of the

  tablecloth in the form of textile fibers or filaments.

  On the other hand, in the case of an intermediate layer in the form of a metal grid, in particular a tightly knitted fabric, produced by knitting one, two or three metallic wires in parallel, the passage of a material to three superimposed layers comprising such a grid in a conventional needling machine produces multiple breaks of the metal wires constituting the grid and the driving of the ends of these wires or of the wires themselves through the first and third layers, which leaves a multiplicity of metallic wires appear on the surface of said layers. This has the drawback on the one hand of weakening the metal grid and on the other hand of giving the material

  composite obtained an unacceptable presentation.

  It is therefore the merit of the invention to have been against an a priori unfavorable prejudice concerning the needling technique and to propose specific conditions allowing the obtaining, by this technique, of a acceptable product. The fact of using needles with rounded ends makes it possible to limit the breakage and the entrainment of the metal wires, during the passage of the needles, the point of the needle coming to slide laterally on the metal wires. In addition, the single-stroke needling makes it possible, even in the event of metal wires being drawn in by the barbs of the needles, to limit the appearance of such wires only on the surface of the third layer, that is to say the one which is in contact with the upholstery element of the seat in the case of such an application. Of course to obtain a binding by a simple needling

  strikes, it is absolutely necessary that the first layer be

even a sheet of nonwoven.

  It should be noted that the use of needles with rounded ends makes it possible to significantly reduce the breakage of needles that would be obtained using traditional needles due to the impact.

  said needles on the metal wires.

  Advantageously, an acceptable bonding of the three layers constituting the composite material of the invention is obtained by setting

  operates a needling density between 10 and 30 strokes / cm2.

  Advantageously, the first and / or the third layer is a pre-needled nonwoven ply with a lower needling density. It is the complementary needling, intended to join the three layers of the composite material of the invention, which makes it possible to complete

  the needling of the nonwoven ply (s).

  Advantageously, the method of the invention comprises a complementary step which consists in carrying out a pressure treatment of the three layers, after needling, carrying out the coating of any metallic wires passing over the external face of the third layer. This treatment can be carried out either by passing between two cylinders or else

  by compression in a hydraulic press.

  Advantageously, each needle, with a rounded tip, has barbs whose depth is less than half the diameter of each of the constituent wires of the metal grid and greater than half the diameter of all or part of the constituent fibers of the first layer. This particular arrangement is very advantageous since it limits or even completely cancels the entrainment by the barbs of the needles of the metal wires, while allowing the entrainment by these same fiber barbs of the first layer for the bonding of the

three layers between them.

  The present invention will be better understood on reading the

  description which will be given of a preferred embodiment of a

  composite material for anti-vandalism and fire protection of a public vehicle seat, illustrated by the appended drawing in which: - Figure 1 is a schematic sectional representation of the three layers before superposition and needling, - Figure 2 is a plan view of the metallic knitted fabric constituting the second layer, - Figure 3 is a schematic sectional view of the material after needling, in contact with a padding element and, - Figure 4 is a schematic perspective view of a

needle fitted to the needling machine.

  The present invention relates to a composite material intended for anti-vandalism protection, in particular but not exclusively of seats for public transport vehicles. What, in this composite material, fulfills the anti-vandalism function is the presence of an intermediate layer which is a metal grid and in particular a

  tight knit metallic knit.

  The presence of such a metal grid makes it possible to envisage other applications than the fight against vandalism, in particular the use of the composite material of the invention in the manufacture of ballistic protective clothing or splinter protection or even bellows

  equipping the space between two compartments of transport vehicles.

  In the example which is illustrated in the various figures, the composite material of the invention consists of three superposed layers, namely a first layer of nonwoven fibers 2 which constitutes the outer layer 3, a metallic knitted fabric 4 which constitutes the intermediate layer and a nonwoven fiber ply 6 which constitutes the inner layer 7. Being a composite material 1 intended for the manufacture of a seat, it is this inner layer 7 which is in contact with the element

padding 8.

  The metallic knitted fabric 4, illustrated in FIG. 2, is produced by knitting two metallic wires 9, 10 in parallel, each of which may have a diameter of approximately 0.2 to 0.3 mm. The stitch size for knitting 4 is

in the range of 10 to 15mm.

  In a specific embodiment, the two sheets of nonwoven fibers 2.6 are pre-needled nonwovens making 80Og / m2 composed of various titration fibers between 1.7dtex and 4.5dtex, having an average diameter of around 12 to 15pm. The three layers 3,5, 7 are superimposed and pass through a conventional needling machine, but equipped with needles 12 with rounded ends 13, of triangular cross section with three barbs 14 per edge 1 5, the nine

  barbs 14 being distributed helically over the entire height of needle 12.

  The needling is carried out on a basis of twenty strokes / cm2 with a penetration of 9mm, knowing that the distance from the tip to the first beard 14 is 3.2mm. The beard depth was 0.08mm (80 / m), with an eighteen gauge as the size of the working part. The needling was carried out by simple strike, the

  needles being located above the first layer 3.

  During needling, it is the transfer of fibers from the first

  woven 2, carried by the barbs 14 of the needles 12, passing through the meshes 16 of the metallic knitted fabric 4 and penetrating into the fibers of the second nonwoven 6 which makes the connection of the three constituent elements

  of the composite material 1 of the invention.

  The entrainment of the fibers is caused by the barbs 14, which are arranged along the edges 15 of each needle 12, and which are constituted by notches 17 surmounted by projections 18. During the penetration of the needle 12, the thread, near the impact of the needle 12, slides along the edge 13, enters towards the notch 17 and, being locked in position by the projection 18, is driven by the needle 12 in its movement. The blocking in position of the wire depends on the configuration of the notch 17 and the projection 18, compared to the

wire diameter.

  It is desired, in the context of the present invention, to selectively entrain the fibers of the first nonwoven web in

  detriment of the wires of the metal grid.

  According to the applicant, the depth of the barbs 14 of the needles should be less than half the diameter of each of the constituent wires of the metal grid of the second layer and greater than half the diameter of all or part of the constituent fibers of the

  non-woven layer of the first layer.

  In the case of a metallic knit produced by knitting two parallel metallic threads, each thread having a diameter of the order of

  0.26mm (260pm), and a first layer which is a non-

  woven formed of fibers having an average diameter between 12 and 1 9, m, the applicant has chosen to work on his needle loom with beard needles whose beard depth is of the order of 0.08mm (8Opm). The rounded tip 13 of the needle 12 is defined so as to come

  slide sideways over the steel knitting wire without damaging it.

  Being a needle 12 of eighteen gauge the tip 13 is a half

0.30mm diameter sphere.

  Thus it was possible to produce the composite material 1 of the invention without significant breakage of needles. If needles are used, the barbs of which would nevertheless locally drive one or the other of the threads 9, 10 composing the metallic knitted fabric 4, then protruding metallic threads 11 would be obtained which, at the exit from the needling machine, would appear in the form of peaks arranged perpendicularly by

  relation to the general direction of the material 1.

  The height of these peaks is a function of the penetration of the needles and the thickness of the composite material. In any event, it is possible to remedy the drawback of having vertical peaks locally, by carrying out on the material 1 after needling a treatment aiming to lay the peaks against the outer face; 6a of the second layer of fibers not -woven 6. This treatment can consist in passing the material 1, after needling, between two steel cylinders of the scarf type between which a determined pressure is exerted or by

  compression of said composite material 1 in a hydraulic press.

  In this case, the visible ends 11a of the peaks are folded down and lie in the plane of the outer face 6a of said nonwoven fabric 6. Due to the needling intended to ensure the connection between the three layers 3,5,7, it is possible to use sheets of nonwoven fibers 2.6 having previously undergone less needling. The difference in needling density will be of the same order as the needling density used to ensure the connection of the three layers

3.5.7.

  Preferably, the nonwovens 2.6 are made from fibers having fire-resistant characteristics. It may advantageously be polyacrylate fibers, such as those sold under the trade name INIDEX. It can also be a mixture, such as that

  recommended in document EP.258.513.

  The present invention is not limited to the embodiment which has just been described by way of non-exhaustive example. In particular the third layer 7 may consist of a woven textile material or

  knitted and not a sheet of non-woven fibers.

  Finally, it should be noted that the selective choice of threads or fibers entrained by the barbs of a needle as described above in the context of the process for manufacturing a composite material for anti-vandalism protection n is absolutely not limited to this application, using three superimposed layers, the intermediate layer of which is a metal grid. The principle of such a selective choice can be applied more generally in the field of needling, using barbed needles, conventional or special, with rounded tip or not, whenever it will be necessary to favor the entrainment of a determined component (son or fibers) in a sheet made up of at least two components (son or fibers) of different diameters. According to this principle, the needles are chosen so that the beard depth is greater than the radius of the component that is preferably to be driven and less than the radius of the other component. Of course, variants can be envisaged in the case where the section of one or the other of the components is not circular.

Claims (6)

  1. Method for manufacturing a composite material for anti-vandalism protection, in particular for seats, consisting in producing a set of three superimposed layers, the intermediate layer of which is a metal anti-vandalism grid and in joining said three layers, characterized in since the first outer layer (3) is a nonwoven (2), it consists of joining the three layers (3,5,7) by simple needling strikes from needles with beards with rounded ends, so that, after needling, the outer face of the first layer is free of metal wires coming from the second layer, and that the outer face of the third layer has a limited or even zero number   metallic wires from the second layer.   2. Method according to claim 1 characterized by a density   needling between 10 and 30 strokes / cm2.   i 5 3. Method according to one of claims 1 to 2, characterized in that the   first (3) and / or third layer (7) is a pre-woven nonwoven   needled with a low needling density.   4. Method according to one of claims 1 to 3, characterized in that it   comprises a complementary step which consists in carrying out a pressure treatment of the three layers (3,5,7), after needling, carrying out the coating of any metallic wires (11) passing over the face   outside (6a) of the third layer (7).   5. Method according to one of claims 1 to 4, characterized in that   The needling is carried out using needles, the depth of the barbs of which is less than half the diameter of each of the wires making up the metal grid and greater than half the diameter of all or part   fibers constituting the first layer.   6. Method according to one of claims 1 to 4, characterized in that the   metal grid being formed by knitting of parallel metal wires of diameter of the order of 260pm and the first layer being a nonwoven sheet composed of fibers having a diameter of the order of 12 to 19pm, the needling is carried out at using needles whose depth of beards is around 80 / m.