NZ528349A - Reinforced fabric - Google Patents

Abstract

A reinforced fabric comprising on its front surface a warp yarn weave (2) in one direction and a weft yarn weave (3) in the perpendicular direction or a mesh-type weave is disclosed. Furthermore, said fabric comprises on its rear surface a reinforcing grid consisting of warp yarns (4) and weft yarns (5) produced in a material having different properties, such as higher mechanical properties than those producing the yarns of the front surface, the reinforcing grid being linked to the front surface by its warp and weft yarns, the warp yarns (4) and the weft yarns (5) being fixed on the front surface in different points and intersecting outside the ground fabric forming the front surface.

Description

528349 REINFORCED FABRIC The subject of the present invention is a reinforced fabric. It may be, in particular, a fabric used in a 5 garment for individual protection, especially a thermal protection fabric for the production of garments used by firefighters or else a fabric used in hazardous environments, for mechanical or chemical protection, protection against an electric arc, protection in the 10 case of explosive surroundings, etc.

In the field of Individual Protection Equipment (IPE), various types of textiles are employed in order to meet the requirements of the standards in force and thus 15 ensure the necessary and sufficient protection for each of the wearers of garments.

Thus, by way of example, there are flame-retarding textiles for firefighters, for which thermal 20 performances (resistance to radiant and convective heat, thermal stability, inflammability test, etc.), but also mechanical, antistatic, waterproofing and suchlike performances, are measured. There are al^ other types of fireproof textiles for industrial 25 workers exposed to heat, where the performance requirements relate mainly to resistance to limited flame propagation and resistances to convective and radiant heats. There are likewise protective garments used for welding operations, which must have 30 characteristics of nonflammability, of resistance to tear propagation and of resistance to small splashes of molten metals.

The examples given above show that there is very often a combination of a plurality of characteristics to 35 ensure that a textile is conformable. What are generally combined are mechanical performances (tensile strength and tearing strength) and thermal performances WO 02/079555 PCT/FR02/01100 or mechanical and chemical performances or else mechanical and antistatic performances.

The textiles for individual protective equipment which are on the market at the present time use various types of raw materials ranging from treated flame-retarding cottons to aramides and other fireproof fibers or filaments of the latest generation. The choice of raw material determines the type of protection of the finished textile, its performance level, its method of care, its price level and its useful life.

To be precise, the more the choice tends toward a top of the range material possessing high performances, the more the fabric affords good protection and greater durability, but at a high price. By contrast, a textile produced from a lower-range flame-retarding material has lower performances and shorter useful life, but will be at a more attractive price level. Since the purpose is always to obtain the fabric which has the best performances and the best comfort for a competitive price, textiles which are both high-performance, resistant, lightweight and comfortable are therefore sought after.

One means for improving the tear propagation of a fabric is to use a weave known by the designation RIP STOP, which involves doubling a thread regularly in warp and in weft, so as to block the propagation of the tear. Such a weave makes it possible to increase the tear propagation values by 30%. The disadvantage of using such a weave is that of obtaining a fabric with some relief on the front face which gives rise to premature wear of these doubled threads and therefore to a lower abrasion resistance than in a smoother weave, such as linen or twill.

WO 02/079555 PCT/FR02/01100 It is therefore inadvisable to use this type of weave on a fabric intended to be printed (army camouflage type), since resistances to dry and wet friction would be adversely affected on account of this relief where 5 abrasion is preponderant.

Moreover, a RIP STOP weave always gives a more marked appearance which may be prejudicial to use, in contrast to smoother weaves, such as twills.

One other means for increasing the mechanical resistances of a fabric is to use an industrial thread of the "core thread" type or equivalent, where the raw material having the highest mechanical resistance is 15 placed in the core of the thread and is covered by one or more other raw materials which have lower mechanical resistance, but which afford the coloristic and antistatic properties of the final thread, and also effective protection of this core with respect to UV, 20 to abrasion and to the attacks associated with the care of the garments.

The disadvantages of these spinning techniques are as follows: what is very often involved is a complicated 25 technology which is limited in terms of thread fineness and which gives a less substantial proofing of the textile. This is the case, for example, with the spun core Kermel® HTA®, where the Technora® (paraaramide of high mechanical performance) is placed in the core to 30 provide the strength of the thread, and where the Kermel® (polyamide imide) is placed in the covering to give the final color of the product and the protection of the core. Thus, the fabrics produced with this type of thread use a thread of medium fineness - Nm 45/2 -35 in comparison with fabrics produced from Nomex Delta TA® (intimate mixture of meta and paraaramide) constructed with a thread of higher fineness - Nm 55/2 - which, with an equivalent fabric weight, makes it WO 02/079555 PCT/FR02/01100 possible to obtain a more sufficient thermal screen, since the surface of the Nomex Delta TA® fabric is more closed. By contrast, a fabric formed from an intimately mixed industrial thread, such as Nomex Delta TA (75% 5 meta aramide, 23% paraaramide, 2% antistatic) has lower mechanical performances than the spun core mentioned above.

Another means for improving the mechanical performances 10 of a textile is to insert a thread having high mechanical performances regularly in one direction and/or the other of the textile, without modifying the construction of the textile. Fabrics having higher mechanical resistance are thus obtained, since the new 15 inserted thread very often contains a high percentage of paraaramide; however, this thread may have the disadvantage of bleaching during use and with successive washes, thus giving the textile an old, uneven and whitish surface appearance.

To obtain a textile having antistatic properties, it is known to use a conductive or antistatic material in intimate mixture with the other component materials of the textile; this mixture may be uniform in a low 25 proportion in the entire textile or else be more concentrated regularly on some threads in both directions. In both cases, depending on the antistatic material used, the latter appears to a greater or lesser extent on the surface of the textile, thus 30 giving a more or less marked veined appearance or barred or streaky effect which may be a disadvantage, above all with regard to light colors. Only a core thread technology with an antistatic core and a covering made from another material makes it possible 35 to produce a uniformly colored textile; the disadvantage, as mentioned above, is the high cost of such a thread.

The object of the invention is to propose a textile for which some performances will have been improved, combined^ and added, with a view to optimizing its capacity for industrial use, this being without one of its faces being changed aesthetically, while at the same time preserving its textile properties. This object should be read disjunctively with the further object of at least providing a useful alternative.

To achieve this, the thermal protection fabric to which the invention relates, comprising, on its front face, a weave of warp threads in one direction and of weft threads in the perpendicular direction or a weave of the mesh type, is characterized in that it comprises, on its back face, a reinforcing grid composed of warp threads and of weft threads produced from a material possessing different properties, such as higher mechanical properties than those producing the threads of the front face, the reinforcing grid being connected to the front face by means of its warp and weft threads, the warp and weft threads being fastened to the front face at different points and intersecting on the outside of the ground fabric forming the front face.

The reinforcing threads belonging to the reinforcing grid are connected to the front face in a punctiform manner and intersect, thereby giving rise to extra thicknesses which trap an air layer contributing to a better thermal insulation of the fabric. This is particularly important when the fabric is used for producing a garment intended for firefighters, the various substances used then being produced from fireproof and nonmeltable materials.

Advantageously, the reinforcing grid is connected to the ground fabric during the manufacture of the latter.

According to one embodiment of this fabric, the reinforcing grid is formed by a linen-type interlacing INTELLECTUAL PROPERTY OFFICE OF N.Z. 17 MAY 2004 WO 02/079555 PCT/FR02/01100 of the reinforcing threads arranged in warp and in weft.

Advantageously, the various threads in the two 5 directions are combined so as to form a complex weave of the linen, twill or satin type, such that the front or outer face of the fabric is composed essentially of the ground threads and the inner face of the reinforcing threads.

These ground threads intersecting, for example, in the manner of twill give a surface appearance similar in all respect to a standard twill fabric (of identical weight and construction) which would not possess this 15 grid. The characteristics of the appearance of the outer surface will thus be preserved.

This construction makes it possible to obtain a high abrasion resistance of the outer face, an excellent 20 preservation of the appearance after washing, and a greater printing capacity by virtue of the high frictional resistances, as compared with a rip stop weave.

The reinforcing threads may, for example, be produced from a material possessing mechanical performances higher than those of the material of the ground thread. An expedient construction is aimed at connecting the reinforcing threads in the ground twill regularly, so 30 as to afford a considerable improvement in terms of the tearing strength and tear propagation, and the dimensional stabilities of the fabric, and also to increase its break-open resistance (opening of the fabric as a result of prolonged exposure to a flame) or 35 its resistance to a flash generated by an electric arc. This type of construction thus makes it possible to produce fabrics which are much more resistant, while having identical weights. It is possible, moreover, to construct textiles of lighter therefore more comfortable, characteristics equivalent to a reinforcing grid.

Moreover, since the reinforcing threads are not connected in the ground, they form small warp and weft floats which intersect perpendicularly, thus giving rise to extra thicknesses at each intersection, these 10 extra thicknesses contributing to the thermal insulation of the fabric. To be precise, this grid effect makes it possible to increase the thickness of the fabric, this thickness being the greater since the floats of the reinforcing threads intersect 15 perpendicularly on the back face, thus forming a multiplicity of small crosses or small points which constantly retain an air layer in this network.

By virtue of this type of construction, it is also 20 possible to choose to incorporate into this grid on the back face materials which are sensitive to external elements (UV radiation, abrasion, etc.).

Thus, in order to obtain a textile with improved 25 mechanical properties, all types of aramide (and especially paraaramides) can be used in the components of the reinforcing thread, since the fibrillation of this thread will be maintained on one of the faces of the textile, without adversely affecting the other face 30 which is the outer face of the fabric.

The reinforcing grid makes it possible, furthermore, to give the fabric additional performances, such as antistaticity or conductivity. What is useful about 35 placing conductive threads on the back face is that this makes it possible to preserve a uniformly colored surface appearance, while at the same time affording electrical properties. weight, which are for mechanical structure without a Other materials may be inserted deliberately into the reinforcing grid, such as carbon fibers or filaments (highly sensitive to abrasion), microencapsulated 5 products, form change materials, grafted threads, etc.

According to one embodiment of this fabric, the weave of the front face is produced in 2/1 twill for a fabric weight of 225 g/m2. The ground threads connect on the 10 front face and the reinforcing threads on the back face. The proportions between the ground threads and the reinforcing threads are as follows: - in warp: 6 ground threads and 1 reinforcing thread, that is to say 1 thread every 2 millimeters, - in weft: 5 ground threads and 1 reinforcing thread, that is to say 1 thread every 2 millimeters.

According to one possibility: - the ground threads are produced from an intimate 20 mixture of meta and paraaramide with a small percentage of carbon polyamide, such as are known under the trademark Nomex Comfort , the count used being Nm 60/2; - the reinforcing threads are produced from cracked paraaramide, such as are known under the trademark Kevlar® or Technora®, the count used being Nm 50/2.

The reinforcing threads form, on the back face, floats of approximately 2 millimeters which intersect perpendicularly, thus forming a small relief point 30 directed toward the rear of the fabric. This gain in thickness of the fabric makes it possible to obtain improved thermal results, as compared with a fabric of identical proofing and weight, without a grid.

This reinforcing grid also makes it possible to increase significantly the breaking and tearing strengths of the fabric. The values obtained were compared with those of a fabric of 100% Nomex Delta C® WO 02/079555 PCT/FR02/01100 of identical weight and construction, but without a reinforcing grid, and a gain of at least 40% was measured for the breaking strengths and of at least 150% for the tear propagations.

Moreover, this article was tested for up to 25 washing and tumbler-drying cycles in order to check the preservation of the appearance; the result is extremely satisfactory, since no fibrillation and no whitish 10 appearance of the surface were found.

By virtue of this construction, in the event that antistatic properties are added to the textile, it will be possible to obtain a' smooth front face of 15 homogeneous composition and color, since the antistatic grid of the back face will be effective, but invisible.

The invention is described below with reference to the accompanying diagrammatic drawing illustrating one 20 embodiment of this fabric.

Figure 1 is a view of a fabric piece seen from inside, that is to say from the side of the reinforcing grid; Figure 2 is a cross-sectional view of this, perpendicularly to the weft threads, along the line II-II of figure 1.

The drawing illustrates a fabric comprising a weave of 30 warp threads in one direction and a weave of weft threads in the perpendicular direction. The warp threads are designated by the reference 2 and the weft threads by the reference 3. This fabric comprises, on its back face, a reinforcing grid composed of warp 35 threads 4 and of weft threads 5. As may be gathered from figures 1 and 2, the warp threads and the weft threads are connected on the front face of the fabric at different points and intersect at points 6 on the WO 02/079555 PCT/FR02/01100 outside of the ground fabric forming the front face. It may be gathered particularly from figure 2 that, at some locations, there are 4 thicknesses of superposed threads, forming a multiplicity of small points which delimit a network retaining an air layer conductive to the thermal insulation afforded by the fabric.

It goes without saying that the invention is not limited to the sole embodiment of this fabric, described above by way of example, but, on the contrary, embraces all the variants remaining within the scope of the claims. Thus, in particular, the front face of the fabric could comprise a weave of the mesh type, without departing from the scope of the invention.

Claims (13)

1. A reinforced fabric of the type comprising, on its front face, a weave of ground threads comprising warp threads in one direction and weft threads in the perpendicular direction or a weave of the mesh type, which comprises, on its back face, a reinforcing grid composed of warp threads and of weft threads (the reinforcing threads) produced from a material possessing different properties than those producing the threads of the front face, the reinforcing grid being connected to the front face by means of its warp and weft threads, the reinforcing threads being fastened to the front face at different points and intersecting on the outside of the ground fabric forming the front face.

2. The fabric as claimed in claim 1, in which the material possessing different properties has high mechanical properties than those producing the threads of the front face.

3. The fabric as claimed in claim 1 or claim 2, in which the reinforcing grid is connected to the ground fabric during the manufacture of the latter.

4. The fabric as claimed in any one of claims 1 to 3, in which the reinforcing grid is formed by a linen-type interlacing of the reinforcing threads arranged in warp and in weft.

5. The fabric as claimed in any one of claims 1 to 4, in which the ground threads and the reinforcing threads in the two directions are combined so as to form a complex weave of the linen, twill or satin type, such that the front or outer face of the fabric is composed essentially of the ground threads and the inner face of the reinforcing threads.

6. The fabric as claimed in any one of claims 1 to 5, in which the threads of the reinforcing grid are of high tenacity. /INTELLECTUAL PROPERTY 1 OFFICE OF N.Z. I 17 MAY 2004 - 12 - I INTELLECTUAL OFFICE rv 11 MAr 2004 RECEIVED

7. The fabric as claimed in claim 6, in which the threads of the reinforcing grid are of aramide.

8. The fabric as claimed in claim 6 or claim 7, in which the threads of the reinforcing grid are produced from cracked paraaramide.

9. The fabric as claimed in any one of claims 1 to 8, in which the ground threads of the front face of the fabric are produced by an intimate mixture of meta and paraaramide with a small percentage of carbon polyamide.

10. The fabric as claimed in claims 8 and 9 taken as a whole, in which the weave of the front face is produced in 2/1 twill for a fabric weight of 225 g/m2, the proportions between the ground threads and the reinforcing threads being as follows: - in warp: 6 ground threads and 1 reinforcing thread, that is to say 1 thread every 2 mm, - in weft: 5 ground threads and 1 reinforcing thread, that is to say 1 thread every 2 mm, the count of the ground threads being Nm 60/2 and the count of the reinforcing threads being Nm 50/2.

11. The fabric as claimed in any one of claims 1 to 5, in which the reinforcing grid contains other elements selected from carbon fibers or filaments, microencapsulated products, form change materials and grafted threads.

12. A reinforced fabric substantially as herein described with reference to either one or both of the accompanying drawings.

13. A reinforced fabric as claimed in any one of claims 1 to 11, substantially as herein described.