EP1111114B2 - Textile mesh with a reduced thickness - Google Patents

Abstract

A textile grill, comprises at least two warp layers and at least one weft layer of nonwoven fabric. An adhesive holds the layers together where they intersect. The grill has a performance level (TP) of ≥ 30, given a specific relationship. A textile grill, comprises at least two warp layers and at least one weft layer of nonwoven fabric. An adhesive holds the layers together where they intersect. The grill has a performance level (TP) given by equation (I). TP = S x 100 divided by ( T x E x C) ≥ 30 (I) C = factor for the adhesive, = 0-1; E = grill thickness (mm); S = surface area of intersection points (mm<2>); and T = quality of the warp and weft fibers (g/km). Independent claims are included for: (a) an industrial product including the above grill; and (b) the manufacture of the grill, comprises impregnating the assembled layers with adhesive and pressing the grill before the adhesive has dried.

Description

The present invention relates to the general technical field of textile grids formed of a network of warp and weft threads held in place by bonding at the crossover point of the threads, such grids acting in particular as reinforcements or supports in different industrial applications .

The present application discloses a textile grid formed by a network of crossed or superimposed nonwoven threads comprising at least two plies of warp threads between which is interposed at least one ply of weft threads, the warp and weft threads being linked between them at their crossing by a binder creating a series of bonding points.

The present application also discloses any finished or unfinished industrial product incorporating such a textile grid.

The present invention relates to a process for manufacturing a textile grid in which a network of crossed or superimposed nonwoven yarns is produced comprising at least two plies of warp yarns between which is interposed at least one ply of weft yarns, and coated the network of wires with a binder to ensure the connection of the weft and warp threads with each other.

It is already known to produce grids industrially formed from a network of crossed nonwoven threads, the threads being bonded together at their crossing points by impregnation with a binder, of the thermoplastic glue or other type. Known grids such as those illustrated for example in figure 1 , use at least two plies of warp threads A, B, superimposed or even offset, each pair of plies A, B, having interposed between them at least one ply C of weft threads. According to these known embodiments, the warp threads 1 and the weft threads 2 are linked together at their crossing 3 by a binder 4 creating a series of bonding points in order to obtain a textile grid having a finished and stable structure on the mechanical plane.

The grids produced according to this technique generally give satisfaction and serve as reinforcements or supports in very varied technical fields such as for example without limitation, in the building industry, as a support for parquet floors and ceramics or wall coverings and carpets, in the paper industry, or even as a reinforcement element in synthetic or other foams.

Nevertheless, it appears that the textile grids known to date suffer from a certain number of drawbacks and in particular a drawback linked to the relatively large and mainly very irregular thickness of the grid. Indeed, the method of manufacturing known grids involves a simple coating of an adhesive or thermoplastic binder, of the PVC or PVA type for example, without any other additional operation. It follows that the textile grids obtained have a relatively large thickness whatever the nature, type, number of threads used, leading to a relative lack of flexibility of the grid obtained. In addition, the thickness of the textile grids known to date is particularly irregular due to the existence of a relief at the crossing points of the warp 1 and weft 2 threads. The presence of such irregularities at the Textile grids of the prior art obviously have a certain number of drawbacks on the industrial level, and particularly in certain specific applications.

In addition, it turns out that the conventional textile grids exhibit a certain weakness in the mechanical strength of the network of threads glued at the bonding or crossing points between the warp and weft threads.

Finally, the textile grids of the prior art appear to involve a relatively large consumption of the adhesive or thermoplastic binder used, particularly if one wishes to try to reinforce the mechanical strength of the network of wires at the crossing points. . This leads to an increase in the cost price of the products obtained, which constitutes an industrial disadvantage.

In an attempt to at least partially remedy the drawbacks listed above, it has already been envisaged, in particular in the patent GB-1463969 , to produce a textile grid of reduced thickness in which the redistribution of the network of threads is obtained by compression, and in particular by calendering of the grid in order to flatten it. The calendered grid obtained actually has a reduced thickness, for example of the order of 200 to 150 micrometers, in comparison with the conventional grids of the prior art. Such a reduction in thickness by calendering the textile grid is nevertheless accompanied by a partial destruction of the structure of the bonding points between the warp and weft threads, so that the general mechanical resistance to rupture of these points is greatly reduced compared to conventional grids. Furthermore, the technique of compression by calendering of the textile grid is not accompanied by a reduction in the amount of adhesive used. In total, the calendered textile grids, in addition to the relative complexity and difficulty of obtaining the product on the industrial level, suffer from a certain number of drawbacks making their use limited or even inappropriate in certain applications.

The invention aims to propose a new method for manufacturing a textile grid formed by a network of crossed or superimposed nonwoven yarns which is particularly simple to carry out.

The objects assigned to invention are achieved using a method of manufacturing a textile grid as defined in the claims.

• The figure 1 illustrates according to a view in partial section, a detail of embodiment of the structure of a textile grid of the prior art.
• The figure 2 illustrates in a partial cross-sectional view, a detail of the structure of a textile grid produced according to the method of the invention.

According to the invention, as illustrated in figure 2 , the textile grid produced according to the method of the invention is formed by a network of crossed or superimposed nonwoven threads comprising at least two plies A, B, of warp threads 1 between which is interposed at least one ply C of threads of frame 2.

As is well known to those skilled in the art, the construction of the network of warp threads 1 and weft threads 2 is obtained by shifting the warp and weft threads without overlapping, or on the contrary by ensuring a overlapping of the wires. Likewise, the network of warp 1 and weft 2 threads can be obtained with a crossover of the warp and weft threads at 90 ° (square construction) or according to a different angular inclination, for example tri-directional.

By way of non-limiting example, the textile grid may be formed by a number of variable threads, which can, for warp threads, vary from 0.5 thread per centimeter to 8 threads per centimeter, and for weft threads, which can vary, for example, from 0 , 5 threads per centimeter to 5 threads per centimeter.

Without limitation, and as is well known to those skilled in the art, any type of textile thread commonly used to date in the production of textile grids may be used, and for example threads of the Silionne, polyester type, cellulosic, aramids or polyamides.

According to the invention, the warp 1 and weft 2 threads are linked together at their crossing 3 by a binder 4 creating a series of bonding points at the intersection of the network of threads.

Within the meaning of the invention, any binder or adhesive commonly used to date in the technical field considered may be used, and in particular any binder or thermoplastic adhesive. Without limitation, the connection and coating of the network of threads forming the textile grid according to the invention may be formed by synthetic latexes (SBR, etc.), PVAC, plastisols, PVC, polyvinyl alcohol (PVA), conventional iron-on impregnations, polyurethane binders or acrylic binders for example.

It is disclosed that when, taking into account the title of the weft and warp threads used, the structural characteristics of the network of threads of the textile grid are maintained such as the surface of the bonding points, as well as the average thickness of the grid and the rate of glue used or present in the mass of the threads, beyond a minimum value, or within a specific range, remarkable characteristics of behavior of the textile grid were obtained.

It is disclosed a textile grid which has a reduced thickness, and for example preferably less than 0.175 mm and regular without the existence of a significant relief at the crossing of the warp 1 and weft 2 son, while having a excellent mechanical strength of the wire network with a glue consumption lower by at least 30% at least compared to conventional textile grids.

Thus, at the crossings, the thickness of the grid is substantially equal to twice the thickness of the single wire excluding the crossover.

Incidentally, the textile grid obtained has good flexibility as well as a reduced bulk since, in comparison with the known conventional textile grids, the footage wound on the same spool can be multiplied by two in the case of a textile grid conforming to the invention.

A grid is disclosed, the thickness E of which is preferably less than 0.150 mm and even more preferably between 0.150 and 0.06 mm.

The value T is obtained by averaging the titles of the warp and weft threads used: $$\frac{\mathbf{Headline}\mathit{chain}+\mathbf{<figure-callout\; id="2"\; label="title\; weft"\; filenames="imgf0001.png"\; state="\{\{state\}\}">title\; </figure-callout>}\mathit{weft}\mathit{}}{2}$$

Table 1 below expresses in a comparative manner the measured values, characteristic of a fine grid in accordance with the invention and of a normal grid of the prior art, for the same composition of a network of wires for the same thermoplastic binder, for six different compositions of the wire networks. Table 1: BACKGROUND ART GRIDS CONFORMING TO THE INVENTION Wire rack Wire count in gr / 1000m Thickness in mm Glue rate Bonding point area in mm ² PERFORMANCE RATE Thickness in mm Glue rate Bonding point area in mm ² PERFORMANCE RATE Silionne 68 tex grid Warp and weft, EVA glue 68 0.2 0.15 0.16 8 0.1 0.14 0.5 53 PES grid (polyester) 80 dtex Warp and weft, EVA glue 8 0.096 0.38 0.02 7 0.063 0.31 0.09 58 PES grid (polyester) 1100 dtex Warp and weft, EVA glue 110 0.24 0.28 1.23 17 0.175 0.11 2.6 123 PES grid (polyester) 1100 dtex Warp and weft, PVC impregnation 110 0.265 0.42 2.45 20 0.17 0.31 3.5 60 Silionne 34 tex grid Warp and weft, EVA glue 34 0.15 0.22 0.085 8 0.08 0.14 0.17 45 PES grid (polyester) 80 dtex Warp and weft, PVC impregnation 8 0.1 0.53 0.028 7 0.06 0.33 0.09 57

The six exemplary embodiments illustrated in table 1 state grids produced from identical warp and weft threads and also of identical title, it being understood that, within the meaning of the invention, the networks of warp threads and weft of the same grid can be made with threads of different nature and of different title without departing from the scope of the invention. In such a case, the performance rate of the textile grid according to the invention is then calculated by taking the statistical average of the titles of the warp and weft threads.

It thus appears that the textile grids of the prior art, in comparison with the textile grid produced according to the method of the invention, have reduced areas of bonding points, a higher rate of glue and also a greater thickness.

In general, grids of the prior art produced with warp and weft yarns composed of 68 tex glass yarns with an EVA (ethylvinylacetate) thermoplastic binder (adhesive content 20 to 30%) exhibited mechanical resistance to breakage. less than 0.55N, while the breaking strength of grids of the same composition produced according to the process of the invention, with an adhesive content reduced to about 12 to 15% was close to 0.95N.

The application discloses the use of glass yarns whose title of warp and weft yarns is between 5.5 gr / km and 136 gr / km.

The measurement method used to calculate the area of the bonding point expressed in square millimeters was carried out by measuring the overlap area of warp thread 1 on the weft thread and taking the average value from ten measurement points. .

The method used for determining the linear mass or the titer of the wire complies with standard NF G07-317 (ISO 2060 of 06/95) for wires other than glass and carbon. For glass and carbon wires, the method for determining the linear mass, expressed in gr / km, was carried out according to standard T25-020 (ISO 1889 of 08/97).

The thickness of the grid was measured in accordance with standard NF G37-102.

The glue level is expressed by the relation: $$\mathbf{Rate}\mathit{of}\mathit{glue}=1-\frac{\mathbf{the}\mathit{mass}\mathit{of}\mathit{son}\mathit{sure}\mathit{a}\mathit{metre}\mathit{square}}{\mathbf{the}\mathit{mass}\mathit{of}\mathit{the}\mathit{wire\; rack}\mathit{in}g\mathit{sure}\mathit{a}\mathit{metre}\mathit{square}}$$

Such a measurement is carried out on the basis of standard NF T57-511.

According to the invention, the method of manufacturing a textile grid according to the invention and as described above, implements a series of conventional production steps well known to those skilled in the art using conventional parameters of manufacturing adapted to the nature and title of the weft and warp threads used, and to the nature and the rate of glue used.

Thus the manufacturing process implements a general stage of construction of the network of wires, followed by a stage of impregnation and determination of the appropriate rate of glue, then by a stage of drying of the grid obtained.

Devices for the production of such articles are described in numerous patents and in particular in French patents FR-1391900 and FR-2067607 . These devices essentially comprise a rotating element, commonly called a fin, which distributes one or more weft threads around two support elements for rotating threads, spaced from one another so as to form between these elements a series of spaced loops which form a web of wefts. In these devices, the shaft supporting the fin is hollow and at least one of the weft threads is brought to the fin by passage inside said shaft. The rotation of the support elements moves the weft ply laterally, the wire loops forming this ply remaining parallel to each other. This ply of moving wefts is then assembled by gluing with one or more plies of warp threads which are brought into adjacent coplanar relationship with it by means of appropriate guides.

• on réalise un réseau de fils croisés ou superposés non tissés comprenant au moins deux nappes de fils de chaîne entre lesquels est interposée au moins une nappe de fils de trame,
• on imprègne le réseau de fils d'un liant pour assurer la liaison des fils de trame et de chaîne entre eux au niveau de leurs points de croisement.

Thus, the process for manufacturing a textile grid according to the invention is a process in which:

• a network of crossed or superimposed nonwoven yarns is produced comprising at least two plies of warp yarns between which is interposed at least one ply of weft yarns,
• the wire network is impregnated with a binder to ensure the connection of the weft and warp threads to each other at their crossing points.

The peculiarity of the manufacturing process according to the invention resides in the fact of ensuring the pressing of the network of warp and weft threads before the drying phase of the binder is completed, the glue still being in a substantially or completely liquid or fluid state.

Advantageously, the pressing of the network of wires is carried out at least in part simultaneously with the drying phase of the binder.

The manufacturing process can be carried out industrially continuously using conventional elements involving reels, pressing elements and drying elements including a series of cylinders.

The textile grid produced in accordance with the process of the invention can be used as such in the various conventional applications as mentioned above, namely as reinforcing or stabilizing elements. In addition, it can also be used and incorporated into another element to form an industrial product incorporating it.

In particular, it can be glued or laminated to a woven or non-woven element, such as a veil, to form a so-called complex industrial product. In such an embodiment, the structural characteristics to be taken into account for the realization of the grid will be identical to those of the simple grids, the thickness E of the complex grid being that of the grid itself, equal to the thickness of that of the complex minus that of the nonwoven element.

Claims (2)

1. Process for manufacturing a textile mesh formed by an array of nonwoven crossed yarns, which comprises at least two plies of warp yarns between which at least one ply of weft yarns is interposed, the warp and weft yarns being linked together at their intersections by a binder, creating a series of bonding points, characterized by a performance factor (TP) comprised between 45 and 120, the performance factor being calculated using the formula: $$\mathit{TP}=\frac{S}{T\times E\times C}\times 100$$

   

   in which:

   S = area of the bonding points in mm²;

   T = linear density of the warp and weft yarns in g/km;

   E = average thickness of the mesh in mm; and

   C = adhesive content below 0.35,

   $$\mathrm{adhesive}\mathrm{content}=1-\frac{\mathit{mass}\mathit{of}\mathit{the}\mathit{yarns}\mathit{per}\mathit{square}\mathit{metre}}{\mathit{mass}\mathit{of}\mathit{meshing}\mathit{per}\mathit{square}\mathit{metre}}$$

   

   process in which:

   - an array of nonwoven crossed yarns comprising at least two plies of warp yarns, between which at least one ply of weft yarns is interposed, is produced;

   - the array of yarns is impregnated with a liquid binder so as to ensure that the weft and warp yarns are linked together at their points of intersection,

   - a pressing operation is carried out on the array of yarns before the phase of drying the binder has been completed.
2. Process according to Claim 1, characterized in that the pressing of the array of yarns is carried out at least partly at the same time as the phase of drying the binder.

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