Abstract:
The invention proposes a composite textile material for NRBC applications, comprising a first material capable of providing a physical barrier to the penetration of microorganisms and a second material capable of trapping, by absorption and/or adsorption, said microorganisms stopped by said first material and article of protection made of said material.

Description:
This application is a 371 of PCT/FR2006/002760 filed Dec. 15, 2006. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a composite textile material, in particular of the type that protects against nuclear, radiological, biological and chemical attacks, called N.R.B.C., or else in the military field described as chemical warfare agents, as well as protective items manufactured from said material. 
     2. Introduction and Prior Art 
     The protection against the NRBC (nuclear, radiological, biological and chemical) risks requires the use of various protective items (protective clothing, overalls, gloves, socks, hoods, ponchos, covering the body of the user partially or completely, etc., air filtration systems or units . . . ) designed to prevent contact with toxic agents (in liquid or gaseous form) with the skin or mucous membranes of the user. Thus, in the prior art, two ranges of protective items have been developed: those produced from impermeable materials and those using permeable materials. 
     In the first case, the wearer is completely protected from the outside threat, but his body cannot exchange calories with the outside environment. The extended wearing of this type of clothing therefore leads irremediably to problems of hyperthermia that can become deadly. 
     To remedy this problem, clothing that uses air-permeable materials has been developed. This clothing uses a set of textile materials that comprise several layers that consist in general of an outer layer—on the side of the environment outside of the user—, a layer of filter material, and an inner layer—on the side of the user—, with the following characteristics and functions: 
     The outer layer: it consists of an outer textile whose primary functions are to ensure the sturdiness of the clothing—resistance to abrasion and tearing—and to ensure the non-penetration of attacker agents in liquid form. This non-penetration is generally achieved by the application of a hydrophobic and oleophobic treatment on the outer textile, as described in, for example, the document FR-A-2 678 172. 
     The layer of filter material: it ensures the filtration of toxins in gaseous form owing to the adsorbent carbon particles that it contains. The activated carbon particles are in general bonded to a textile substrate or to a non-woven substrate. As examples of these technologies, it is possible to consider: 
     The impregnated foams of activated carbon powder as described in the documents FR-A-2,678,172; U.S. Pat. No. 5,277,963 and the activated carbon balls that are bonded to a textile as described in U.S. Pat. No. 5,334,436. 
     The filter material layer can also come in the form of an activated carbon tissue as taught in U.S. Pat. No. 5,731,065. 
     The inner layer: it consists of a preferably flexible textile and ensures the comfort of the wearer by preventing direct contact of the filter material with the skin. It also plays a role in the storage of sweat. 
     Problems Remaining to be Solved 
     The major problem of materials for protective clothing of the prior art resides in their actual inability to stop the biological threat. Furthermore, the biological threat, in other words the attacks by pathogenic microorganisms, whether it be of bacterial, viral or sporulated nature or of another nature, is conveyed by means of a solid or liquid agent, in particular of the aerosol type. 
     The stopping of liquid or solid particles, in particular an aerosol of approximately 0.1 micron to approximately 10 microns, remains problematic. 
     The prior protective solutions against the NRBC-type biological aerosols reside in the adaptation of the constituent materials of the protective clothing to the threat. 
     Thus, it is known to use an impermeable material, obtained by laminating a film or by “coating,” so as to oppose the threat of biological aerosol, whereby a continuous film does not let any particle pass—as taught in the document FR8917065. This type of material is particularly effective against the penetration of solid or liquid particles but exhibits the major drawback of being airtight. Wearing NRBC protective clothing produced from these materials invariably leads to an important thermal stress that limits the period of use of the clothing. 
     Changes in these materials—airtight but having a permeability to water vapor—have been proposed of the semi-permeable membrane type, such as, for example, the one that is sold under the trade name GORETEX®, but the changes do not make it possible to ensure the thermal comfort level offered by air-permeable materials. 
     In the case of air-permeable protective materials, a reduction of the penetration of the aerosols could be achieved, nevertheless, by means of a reduction of the air-permeability of the protective complex. 
     The permeability as described in this invention is measured according to the standard NF EN ISO 9237. 
     However, the reduction of the air permeability considerably influences the comfort of the clothing, which itself can be quantified by the permeability to water vapor. 
     The permeability to water vapor as taught in this invention is measured by the so-called evaporation resistance according to the standard EN 31092-ISO 11092. 
     Thus, the reduction of the air-permeability of the protective materials of the prior art, regardless of their composition, induces an increase in the evaporation resistance and therefore leads inevitably to a strong reduction of comfort, in particular of protective items such as clothing. 
     There is therefore a need for a material that ensures an effective protection against the NRBC attacks, in particular of the type in biological aerosol form. 
     It is also desirable that this material ensures a real comfort to a protective item manufactured from the latter, in particular by the preservation of an air-permeability property. 
     This invention aims precisely at meeting this requirement. 
     Also, this invention first relates to a composite textile material for NRBC applications that comprises a first material that can create a physical barrier to the penetration of microorganisms and a second material that can trap—by absorption and/or adsorption—said microorganisms that are stopped by said first material. 
     The material according to the invention offers the following advantages:
         Improved effectiveness as to the stopping of biological aerosols   Storage of the microorganisms before they are destroyed   Increased air-permeability, which ensures real comfort.       

     The material according to the invention also offers the following additional or alternative advantages or characteristics:
         Said first material is a non-woven material that is selected from the group that consists of thermoplastic polymers, in particular polyester, polyolefin, with viscose; preferably said material is a polyolefin, and in particular a polypropylene, or a material that is obtained by a process that is selected from among the spun, meltblown, spun meltblown spun, spun meltblown meltblown spun technologies called SMS, SMMS, respectively; this process is preferably SMS.   Said second material is selected from among the thermoplastic polymers, in particular polyamide, polyester, or from among the activated carbons that preferably come in the form of powders and/or fibers, or else from among the zeolites.   Said material according to the invention has an air-permeability.   Said air-permeability of said material according to the invention is selected within an interval of 101 l/m 2 ·s to 1000 l/m 2 ·s that is measured at 100 Pa, preferably about 100 l/m 2 ·s to about 500 l/m 2 ·s.   Said second material is treated by a process that is selected from among the grafting or impregnation techniques so as to make it able to destroy microorganisms that are absorbed and/or adsorbed by said second material.   Said second material comprises at least one agent that is able to destroy the microorganisms, in particular this agent is of the biocide type, preferably grafted on said second material.   Said material according to the invention also comprises a third substrate material that is able to support said second material.   Said substrate material is selected from the group that consists of foams, meshes, fabrics and non-woven fabrics.       

     The object of this invention is also a protective item that is manufactured from the material according to the invention. 
     According to a preferred embodiment, the protective item according to the invention is selected from among protective clothing, overalls, gloves, socks, hoods, ponchos, covering the body of the user partially or completely, air filtration systems or units. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       This invention will now be described in a more detailed manner in its characteristics and advantages using embodiments provided by way of purely illustrative and nonlimiting examples and accompanying drawings in which: 
         FIG. 1  shows an example of a composite textile material ( 14 ) according to this invention that comprises a first barrier material that consists of a non-woven material ( 10 ) and a second material that consists of a substrate material that is made of non-woven material impregnated with a powder ( 12 ) that absorbs the microorganisms. 
         FIG. 2  shows an example of an item manufactured from a composite textile material ( 20 ) according to this invention. This item consists of the material of  FIG. 1  ( 14 ) that is sandwiched between an outer cotton polyester fabric ( 16 ) and a filter material layer made of activated carbon meshes, thermal-bonded onto a comfort textile ( 18 ), in particular made of polyester. 
         FIG. 3  repeats the example that is illustrated in  FIG. 2 , whereby the layer of filter material is a foam that is impregnated with activated carbons ( 22 ). 
         FIG. 4  is a graph that illustrates the linear relationship that exists between the evaporation resistance and the air-permeability, and 
         FIG. 5  is a graph that shows the evolution of the penetration of a biological aerosol based on the air-permeability. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     This invention thus makes it possible to “manage” what happens to the microorganisms that are stopped by the material according to the invention. The thus stopped microorganisms, during the period of use of a permeable NRBC protective item, generally used for 24 hours, can no longer multiply or migrate toward the skin. 
     The object of the protective item according to this invention is also to prevent the migration of stopped microorganisms, to destroy them, according to a preferred embodiment. 
     The inventor of this invention observed that some non-woven fabrics make it possible to get away from the linear relationship ( FIG. 5 ) that exists between the air-permeability and the stopping power of a biological aerosol. 
     EXAMPLES 
     Example 1 
     Composite Textile Material According to this Invention 
     A noteworthy improvement of the performance levels against the biological aerosols is achieved by the use—see FIG.  1 —of an SMS-type barrier non-woven fabric ( 10 ) and a surface mass of 35 g/m 2  of polypropylene that has been treated so as to exhibit properties of water and alcohol resistance. 
     This known material is put on the market under the reference “SMS35” of the PGI Company. This material has an air-permeability of about 270 l/m 2 ·s. 
     A composite textile material according to the invention ( 14 ) that uses the SMS35 non-woven fabric ( 10 ) was produced. By contrast, this material is obtained by the gluing in a conventional manner of a non-woven fabric ( 10 ) to a layer of a filter material ( 12 ), composed of a non-woven polyester that is impregnated with 40 g/m 2  of an absorbent powder as taught in the document FR9912619. 
     This composite textile material ( 14 ) has been tested according to a forced penetration protocol of microorganisms (such as bacillus globigii) in the form of biological aerosol at penetration speeds of about 0.3 cm/s and 1.5 cm/s. This protocol uses an analyzer such as the one that is described by the TNO Laboratories of Rijswijk in The Netherlands. 
     The protective properties of this material according to this invention ( 14 ) are compared to a material of conventional NRBC clothing that is characterized by low air-permeability. 
     The results are provided in TABLE 1 below: 
     
       
         
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Material of the 
                 Material of 
               
               
                   
                 Invention (14) 
                 the Prior Art 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Air-Permeability (100 Pa) 
                 90 l/m 2  · s 
                 23 l/m 2  · s 
               
               
                   
                 Penetration of an Aerosol at 
                 3.8% 
                 29% 
               
               
                   
                 0.3 cm/s 
               
               
                   
                 Penetration of an Aerosol at 
                 9.1% 
                 42% 
               
               
                   
                 1.5 cm/s 
               
               
                   
                   
               
             
          
         
       
     
     It appears that the composite textile material according to the invention, even though the air-permeability is three times more than the known prior material under consideration, allows a clearly improved protection again the microorganisms in the form of a biological aerosol. 
     Example 2 
     Preferred Composite Textile Material According to this Invention 
     In this other embodiment, the composite textile material of the invention ( 14 ), cited in Example 1, was inserted in a material of the prior art as described in  FIG. 2 . This material is used here as an intermediate free lining between an outer fabric ( 16 ) and a layer of filter material ( 18 ). The layer of filter material ( 18 ) is in this case specifically constituted by an activated carbon in the form of a mesh—in particular a mesh such as the one that is put on the market by the Charcoal Cloth Company and sold under the reference FM3K—that is thermal-bonded onto a polyester comfort textile. The outer fabric ( 16 ) that is used is a cotton polyester fabric. 
     The set of materials ( 14 )+( 16 )+( 18 ) is referenced ( 20 ) and shows a preferred embodiment of this invention. It is compared to a prior conventional material that comprises the same components as ( 20 ) except for the material ( 14 ). 
     The results are provided in TABLE 2 below. 
     
       
         
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Material of the 
                 Material of 
               
               
                   
                 Invention (20) 
                 the Prior Art 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Air-Permeability (100 Pa) 
                 95.2 l/m 2  · s 
                 149.2 l/m 2  · s 
               
               
                   
                 Penetration of an Aerosol at 
                 1.1% 
                 63.6% 
               
               
                   
                 0.3 cm/s 
               
               
                   
                 Penetration of an Aerosol at 
                 9.8% 
                   74% 
               
               
                   
                 1.5 cm/s 
               
               
                   
                 Evaporation Resistance 
                 6.4 m 2  · Pa/W 
                 5.5 m 2  · Pa/W 
               
               
                   
                   
               
             
          
         
       
     
     It appears that the use of a material ( 20 ) according to this invention makes it possible to considerably reduce the penetration of the biological aerosols, while preserving a strong air-permeability of about 95 l/m 2 ·s measured at 100 Pa. 
     This result is particularly noteworthy. 
     Actually, if reference is made to  FIG. 5 , we note that a material of the prior art that has an air-permeability of about 95 l/m 2 ·s measured at 100 Pa leads to a penetration value of a biological aerosol of 40%. 
     With a material according to this invention as produced in Example 2 as explained above, the penetration is limited, in a completely surprising manner, to 1%. 
     Example 3 
     Most Preferred Composite Textile Material According to this Invention 
     The material according to the invention of Example 2 has been modified in its composition in that the filter material layer ( 22 ) as illustrated is composed here of a foam that is impregnated with activated carbons, as taught in the document FR9107860. 
     The composite textile material according to the invention ( 24 ) is illustrated in  FIG. 3  and is compared to a prior conventional material that comprises the same components with the exception of the filter material layer ( 14 ). 
     The results are provided in TABLE 3 below. 
     
       
         
               
               
               
             
               
               
               
             
           
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                 Material According to the 
                 Material of 
               
               
                   
                 Invention (24) 
                 the Prior Art 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Air-Permeability (100 Pa) 
                 94.9 l/m 2  · s 
                 200 l/m 2  · s 
               
               
                 Penetration of an Aerosol at 
                 2.4% 
                 72% 
               
               
                 0.3 cm/s 
               
               
                 Penetration of an Aerosol at 
                  14% 
                 77% 
               
               
                 1.5 cm/s 
               
               
                 Evaporation Resistance 
                 7.6 m 2  · Pa/W 
                 6.6 m 2  · Pa/W 
               
               
                   
               
             
          
         
       
     
     It appears that the use of a material ( 24 ) according to this invention makes it possible to considerably reduce the penetration of biological aerosols, while preserving a strong air-permeability of about 95 l/m 2 ·s, measured at 100 Pa. 
     It should also be noted that the material of the invention has a low-evaporation resistance that ensures improved comfort for the user of a protective item manufactured from the material according to this invention. 
     This result is particularly advantageous compared to those obtained thus far using conventional materials of the prior art.