Abstract:
A conventional permeable ABC protective clothing material comprises an internal laminate ( 30 ) comprising individual permeable layers together with an adsorptive layer ( 33, 33 ′) containing activated carbon, and a tear-resistant, hydrophobic and oleophobic covering material ( 10 ). The permeable ABC protective clothing material is to be developed such that the protective effect is raised without appreciable deztriment to the wearing comfort of permeable clothing and thus to the efficiency of the wearer of the suit. To this end, between the internal laminate ( 30 ) and the covering material ( 10 ) there is disposed a layer of filtering material and the layer of filtering material is a fine-pored nonwoven filter fabric ( 20 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a permeable ABC protective clothing material, to the use thereof, and to an ABC protective suit composed thereof. 
         [0002]    U.S. Pat. No. 5,017,424 discloses a transpirable ABC protective clothing material and is primarily concerned with the high elasticity thereof. On the one hand, body movements should be taken into consideration, but on the other hand, the number of regular clothing sizes should be kept down. The ABC protective clothing material is a laminate. An inner layer serves the purpose of guarding against sebum secreted by the wearer. The inner layer further protects against the penetration of particles of suspended matter having a size of 1 μm and less (column 2, line 10). A middle layer comprises an adsorptive material containing activated carbon. An outer layer provides mechanical protection. 
         [0003]    The ABC protective clothing material disclosed in EP 1 269 877 A2 and EP 1 308 186 A2 comprises an internal laminate and a covering material. The internal laminate has a membrane. Although the membrane protects from chemical and/or biological substances or super-fine particles, it is not to be regarded as air-permeable despite a certain degree of vapor permeability. For this reason, there is only insufficient escape of the body perspiration and body heat of the wearer to the environment. 
         [0004]    A protective suit material of the same type is disclosed in DE 195 19 869. This specification reveals a permeable protective suit material having an internal laminate facing toward the wearer. The internal laminate consists of individual permeable, laminate-coated layers having at least one layer which contains activated carbon. Furthermore, the protective suit material comprises a tear-resistant, hydrophobic and oleophobic covering material (page 3, line 32). The protective suit material is air-permeable. By convection, the body heat and body perspiration of the wearer of the protective suit can escape to a high degree in a pleasant manner for the wearer. 
       SUMMARY OF THE INVENTION 
       [0005]    It is an object of the invention to provide a permeable ABC protective clothing material of the above type such that the protective effect is improved without appreciable detriment to the wearing comfort of permeable clothing and thus to the efficiency of the wearer of the suit. 
         [0006]    This object is achieved, according to the invention, by an ABC protective clothing material having the features of claim  1 . Furthermore this object is achieved by the use of a layer of filtering material as defined in claim  11  and by an ABC protective suit as defined in claim  21 . 
         [0007]    The advantages of the invention derive from the fact that an additional layer of filtering material is disposed between the internal laminate and the covering material. This layer of filtering material is a fine-pored nonwoven filter fabric displaying high air permeability. The nonwoven filter fabric efficiently blocks the passage of harmful super-fine particles and aerosols without further impairing the air permeability. In this way there is no loss of the high heat dissipation afforded by convection, and the efficient removal of body perspiration is also maintained. The nonwoven filter fabric supplements in a simple and efficient manner the function of the internal laminate with its adsorption layer and that of the hydrophobic and oleophobic covering material. Conventional permeable ABC protective suits bind the mostly gaseous harmful and toxic substances by means of adsorption in a safe manner. This makes use of the molecular dipolarity. The advantages of the nonwoven filter fabric are useful, on the other hand, with regard to aerosols and super-fine dusts. These consist mainly of combinations of several molecules that are apolar. These apolar particles are advantageously retained by the nonwoven filter fabric. These apolar particles are not adsorbed by the adsorptive layer until they transform to the vapor phase. 
         [0008]    According to one embodiment of the invention, the nonwoven filter fabric consists predominantly of microfibers having a diameter of from 0.1 to 10 μm. Such thin fibers make it possible to achieve the desired fine-pore characteristics. 
         [0009]    According to another embodiment of the invention, the nonwoven filter fabric consists of at least two individual layers of nonwoven filter material which are interconnected in a dot-matrix-like manner. The advantage achieved thereby is that if a layer of nonwoven filter fabric exhibits individual pores which are too large, then an adjacent layer of nonwoven filter fabric having pores within the required tolerances will retain the super-fine particles. 
         [0010]    According to another embodiment of the invention, the nonwoven filter fabric has a pore size of less than 1 μm. This has the effect that even extremely fine particles are retained. 
         [0011]    According to another embodiment of the invention, the nonwoven filter fabric is designed in such a manner that super-fine particles having a size of 1 μm are retained to an extent of more than 99%. In this way high retentivity is achieved combined with good permeability to gases. 
         [0012]    According to another embodiment of the invention, the nonwoven filter fabric displays an air permeability of from 50 to 2500 mm/s. This guarantees good permeability of the protective suit. 
         [0013]    According to another embodiment of the invention, the nonwoven filter fabric displays an air permeability of from 250 to 1100 mm/s. This is the preferred range. 
         [0014]    According to another embodiment of the invention, the nonwoven filter fabric reduces the air permeability by not more than 70% based on an ABC protective clothing material not containing nonwoven filter fabric. This high level of air permeability would not be attainable using an air-impermeable membrane which is permeable to water vapor. 
         [0015]    According to another embodiment of the invention, the attachment of the nonwoven filter fabric to the covering material and the internal laminate is carried out using seams. The advantage resides in the fact that such a joining technique does not depreciate from the desired high permeability to gas, unlike bonding with an adhesive. 
         [0016]    According to another embodiment of the invention, the nonwoven filter fabric is laminate-coated over the covering material by means of adhesive dots to form an outer layer. This alternative method of attachment provides the advantage of a simple cut design involving less sewing. This reduces the production costs. However, this also somewhat reduces the permeability to gases. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    An exemplary embodiment of the invention is described below in greater detail with reference to the drawings, in which 
           [0018]      FIG. 1  is a cross section through a permeable protective suit fabric, 
           [0019]      FIG. 2  is a cross section through another permeable protective suit fabric. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIG. 1  shows a first example of a permeable ABC protective clothing fabric. It comprises an internal laminate  30  consisting of individual permeable layers with an adsorptive layer  33  containing activated carbon, and a tear-resistant, hydrophobic and oleophobic covering material  10 . Between the said internal laminate  30  and the said covering material  10  there is disposed a layer of filtering material. The layer of filtering material is a fine-pored nonwoven filter fabric  20  displaying high air permeability. The ABC protective clothing material functions as follows. When aerosol passes through the covering material  10 , it is almost completely retained in the nonwoven filter fabric  20 . When the aerosol transforms to the gas phase, this gas is captured by the adsorptive layer  33  of the internal laminate  30 . 
         [0021]    Details of the nonwoven filter fabric  20 , covering material  10 , and internal laminate  30  are described in greater detail below. 
       Nonwoven Filter Fabric  20   
       [0022]    The nonwoven filter fabric  20  has predominantly microfibers having a diameter of from 0.1 to 10 of μm. The production of these microfibers is carried out by the melt blown process. 
         [0023]    The nonwoven filter fabric  20  comprises two to five individual layers of nonwoven filter fabric which are interconnected in a dot-matrix-like manner. Each matrix dot represents a fabric connection point. Individual fibers are fused together at the matrix dots. 
         [0024]    The aforementioned structure of the nonwoven filter fabric  20  results in the pores being approximately the same size and uniformly distributed. If a super-fine particle should pass through an exceptionally large pore of a layer of nonwoven filter fabric, this super-fine particle will be retained by the adjacent layer of nonwoven filter fabric. 
         [0025]    This structure involving a plurality of layers of nonwoven filter fabric composed of fibers in the thickness range of from 0.1 to 10 μm makes it possible for the resulting nonwoven filter fabric to have a pore size of less than  1  Am. 
         [0026]    A nonwoven filter fabric  20  designed in such a way further retains super-fine particle having a size of 1 μm to an extent of more than 99%. These statements are subjected to and refer to the testing conditions according to NATO-STANAG 4548. 
         [0027]    The nonwoven filter fabric  20  has an air permeability of from 50 to 2500 mm/s. The preferred range is between 250-1100 mm/s. The more preferred range is between 380 and 500 mm/s. 
         [0028]    All of the air permeability values stated in this application in units of mm/s represent values according to DIN EN ISO 9237. 
         [0029]    The nonwoven filter fabric  20  reduces the air permeability by not more than 70% as compared with an ABC protective clothing material not containing a nonwoven filter fabric. 
         [0030]    The nonwoven filter fabric has a weight per unit area of 45 g/m 2  and a thickness of 0.40 mm. Alternatively, the nonwoven filter fabric may have a weight per unit area of from 30 to 75 and a thickness of from 0.1 mm to 0.6 mm. 
         [0031]    The material is polyethylene or can alternatively be polypropylene, polyester, polyamide, polyacrylonitrile, viscose, PTFE (Teflon), or mixtures thereof. 
         [0032]    Suitable nonwoven filter fabrics used are those nonwoven filters specifically designed for filtering purposes, as used, for example, for gas and liquid filtration. 
         [0033]    Iron-on nonwoven fabrics are completely unsuitable for use as nonwoven filter fabrics. For firstly, the pores are too large for the relevant manufacturing tolerances since iron-on nonwoven fabrics are only used as reinforcing or covering materials. Secondly, thick fibers are used which have a diameter of between 50 and 500 μm. Fine pores cannot be attained by such means. 
       Covering Material  10 : 
       [0034]    The covering material forming the top layer consists in the present example of 98% polyester containing 2% of antistatic fibers. Its thickness is 0.5 mm, its weight per unit area 190 g/m 2 . 
         [0035]    Alternatively, the covering material may consist of polyester/cotton, polyamide, polyamide/cotton, or polyester/polyamide. 
         [0036]    The fabric is bound in the manner of warp-satin. Atlas, satin, linen, or twill would also be possible. The fabric with its fluorocarbon finish is permanently hydrophobic and oleophobic. Furthermore, the fabric has a permanent antistatic finish. The fabric has an air permeability of 750 mm/s. The air permeability may alternatively be between 250 and 900 mm/s. 
         [0037]    The antistatic action is improved by the addition of antistatic fibers such that the resistance does not rise excessively after several washing cycles. 
         [0038]    The breaking stress is despite the high air permeability in both weave and weft directions not less than 1000 N/5 cm (DIN 53857/ISO 5081). 
       Internal Laminate  30 : 
       [0039]    As mentioned above, the internal laminate  30  consists of individual permeable layers together with an adsorptive layer  33  containing activated carbon. 
         [0040]    The adsorptive layer  33  is adjoined on the inside by a supporting layer  31 . On the outside, the adsorptive layer  33  is adjoined by an iron-on nonwoven fabric  34 . 
         [0041]    The material thickness of the internal laminate  30  is between 0.4 and 1.0 mm. 
         [0042]    The adsorptive layer  33 , the supporting layer  31 , and the iron-on nonwoven fabric  34  will now be considered in detail. 
         [0043]    The adsorptive layer  33  is a layer of woven or knitted fabric containing fixed activated carbon particles. The adsorptive layer  33  is laminated to the supporting layer  31  with the aid of an adhesive network  32 . Alternatively, the adhesive network could be replaced by adhesive dots. The adsorptive layer  33  has a weight of from 70 to 150 g/m 2 . 
         [0044]    The supporting layer  31  is skin friendly. The ABC protective clothing material can therefore be worn with or without underwear. The supporting layer  31  is a woven or knitted fabric having a weight per unit area between 50 and 120 g/m 2 . The material is cotton. Alternatively, viscose, polyester, polyamide, or mixtures thereof can be used. 
         [0045]    The iron-on nonwoven fabric  34  is adhesively attached to the adsorptive layer  33  by means of adhesive dots  35 . The iron-on nonwoven fabric consists of polyamide/polyester, but may alternatively consist of polyester, polyamide, viscose, or mixtures thereof. Its weight per unit area ranges from 15 to 50 g/m 2 . 
         [0046]    Now the second exemplary embodiment illustrated in  FIG. 2  will be considered. In this case it may be firstly mentioned that the nonwoven filter fabric  20 , the covering material  10 , the supporting layer  31 , and the iron-on nonwoven fabric  34  are the same as those used in the example illustrated in  FIG. 1 . 
         [0047]    However, the second exemplary embodiment differs, first of all, in the manner in which the nonwoven filter fabric  20  is attached. In the example shown in  FIG. 1 , the attachment of the nonwoven filter fabric  20  to the covering material  10  and internal laminate  30  is effected purely by sewing along the seams  90 . This does not impair the air permeability. By contrast, in the example shown in  FIG. 2 , the nonwoven filter fabric is laminated to the covering material  10  by means of the adhesive dots  11  shown to form an outer laminate  5 , in order to simplify production. 
         [0048]    Another distinguishing characteristic between the first and second exemplary embodiments relates to the design of the adsorptive layer. In the example illustrated in  FIG. 1 , the adsorptive layer  33  in the internal laminate  30  is a layer of a woven or knitted fabric containing particles of activated carbon. On the other hand, in the example shown in  FIG. 2 , the adsorptive layer  33 ′ in the internal laminate  30  consists of a flat arrangement of adhesive dots and spherical adsorbers  36  fixed thereto. Attachment of the spherical adsorbers  36  was effected using a so-called wet adhesive process. In such a process, first of all adhesive dots  37  were printed onto the supporting layer  31 . This was carried out using an adhesive paste in conjunction with a perforated template. Then the spherical adsorbers were scattered over the wet adhesive dots  37 . The excess was sucked off. Curing and fixation of the spherical adsorbers were effected by heating. The amount of spherical adsorber applied is between 120 and 180 g/M 2 . 
         [0049]    In the present example involving the adsorptive layer  33 ′ holding spherical adsorbers  36 , it is possible to omit the iron-on nonwoven fabric  34 , if desired. This applies to applications in which the ABC protective suit is to be designed for exposure to low stresses. As an example, mention can be made of an ABC protective suit for fighting pilots. In the case of high stresses, such as occur in ground fighting, the iron-on nonwoven fabric must, however, be kept, to ensure that the individual spherical adsorbers cannot be rubbed off.