WO2008118955A1

WO2008118955A1 - High durability composite fabric

Info

Publication number: WO2008118955A1
Application number: PCT/US2008/058255
Authority: WO
Inventors: Veli E. Kalayci; Mark A. Gogins; Kristine M. Graham; Michael J. Hebert; Holly C. Axtell; Stephen M. Klem; Robert J. Smith
Original assignee: Danaldson Company, Inc.; Gentex Corporation
Priority date: 2007-03-27
Filing date: 2008-03-26
Publication date: 2008-10-02

Abstract

A composite web of elastomeric nanofiber and at least one type of active particle is provided. Different types of active particles are easily incorporated into one nanofiber layer. Alternatively, multiple layers of web can be provided, wherein the same or different active particles can be incorporated in each layer. Active particles can absorb, adsorb, or react, or a combination of sorb and react with electromagnetic, chemical, and/or biological agents. The composite webs can form effective barrier layers toward a variety of materials. The composite webs can be provided on a substrate. When the substrate is a fabric, the composite webs of the invention can be incorporated into a protective garment. Protective garments of the invention are lightweight, soft, have good drape, and the active particles are durably held in place during the flexing, stress, and strain commonly encountered in garment applications.

Description

HIGH DURABILITY COMPOSITE FABRIC

This application is being filed on 26 March 2008 as a PCT International Patent application in the name of Donaldson Company, Inc., and Gentex Corporation, both U.S. national corporations, applicants for the designation of all countries except the US, and VeIi E. Kalayci, a citizen of Turkey, and Mark A. Gogins, Kristine M. Graham, Michael J. Hebert, Holly C. Axtell, Stephen M. Klem, and Robert J. Smith, all citizens of the U.S., applicants for the designation of the US only, and claims priority from provisional application Serial No. 60/908,202, filed March 27, 2007, and which is incorporated herein by reference.

Field of the Invention

The invention relates to a web structure. The web structures of the invention can act as a reactive, adsorptive or absorptive layer in a filtration or barrier mode. The web structure comprises an elastomeric nonwoven nanofiber web in a composite structure with an active particulate. The active particulate can act as an absorbent, adsorbent, or reactant means. The elastomeric nanofiber secures particles within the web with surprisingly high effective adhesion. The nanofibers also hold smaller particles in place than can conventional nonwoven webs, resulting in high available particle surface area. The invention further relates to textile and other articles comprising the elastomeric nonwoven nanofiber composite webs that are useful in protective applications such as hazardous materials garments and other protective gear. The elastomeric nonwoven nanofiber composite webs of the invention exhibit surprisingly high durability in protective garment applications.

Background of the Invention

Polymer webs can be made by extrusion, melt spinning, air laid and wet laid processing, etc. The manufacturing technology of filter structures is vast for obtaining structures that can separate the particulate load from a mobile fluid stream. Such filtration media include surface loading media and depth media in which these media can be produced in a variety of geometric structures. Principles relating to the use of such media are described in Kahlbaugh et al., U.S. Patent Nos. 5,082,476; 5,238,474; 5,364,456 and 5,672,399. Surface loading filter media often comprise dense mats of fiber having a non-woven structure that is placed across the path of a mobile fluid stream. While the mobile fluid stream passes through the structure of the formed non-woven fibers, the particulate is typically removed from the stream at the filter surface with a certain efficiency and remains on the surface.

Many mobile fluid phases, including both gas and liquid phases, contain undesirable components suspended, dissolved, or otherwise entrained within the mobile phase. Such undesirable components may be chemically reactive or may be absorbable or adsorbable through the use of absorbents or adsorbents. Often these species form a phase that is fully miscible in the fluid and cannot be filtered, but can be removed only by chemical reaction absorbents or adsorbents. Examples of such materials are acidic or basic reacting compounds. Acid compounds include hydrogen sulfide, sulfur dioxide and other such species basic components include ammonia, amines, quaternary compounds and others. Further reactive gases such as Cl₂, SO₂, cyanide, phosgene and others can pose hazards. Lastly, a number of other compounds are objectionable due to odor, color or other undesirable properties. The removal of all such materials from a fluid phase, if possible, can be helpful in many end uses.

To solve these problems, filter media have been developed that further entrain active materials to absorb, adsorb, or react with these harmful agents.

However, the active layers of existing systems suffer from problems relating to the mechanical instability of the particulate in the layers. In many structures the particulate is not mechanically fixed in the layer and can be dislodged easily. In many structures, the amount of active materials available is limited by the nature of the substrate and the amounts of active material that can be loaded. In other structures, the means of anchoring the active materials adds to the bulk of the web, making it impractical to use in some applications such as protective garment applications.

Groeger et al., U.S. Patent Nos. 5,486,410 and 6,024,813 teach a fibrous structure typically made from a bicomponent, core/shell fiber, containing a particulate material. The particulate comprising an immobilized functional material held in the fiber structure. The functional material is designed to interact with and modify the fluid stream. Typical materials include silica, zeolite, alumina, molecular sieves, ion exchange resins, etc. that can either react with, or absorb materials, in the fluid stream.

Markell et al, U.S. Patent No. 5,328,758, use a melt blown thermoplastic web and a sorbative material in the web for separation processing. Errede et al., U.S. Patent No. 4,460,642, teach a composite sheet of PTFE that is water swellable and contains hydrophilic absorptive particles. This sheet is useful as a wound dressing, as a material for absorbing and removing non-aqueous solvents, or as a separation chromatographic material. Kolpin et al., U.S. Patent No. 4,429,001, teach a sorbent sheet comprising a melt blown fiber containing super absorbent polymer particles. Deodorizing or air purifying filters are shown in, for example, Mitsutoshi et al., JP 7265640 and Eiichiro et al., JP 10165731.

Bluecher et al., U.S. Pat. No. 4,510,193 discloses a flat filter with adsorbents fixed thereto, as well as a process for its production. To fix the adsorbents, which consist particularly of activated carbon, the support material is provided with an adhesive or with adhesive spots. The support material is, for example, a textile support structure, while the adhesive is a solvent-free polyurethane. This type of flat filter is especially used in industry but also in the household and for protective clothing. A drawback of this known flat filter is that the adsorbents remove only certain components from the fluid. A filtration of the fluid flowing through it that will remove both gaseous and solid or particulate components is not possible with this filter type.

Hart, U.S. Patent Nos. 4,045,609 and 4.046,939 discloses foam materials and laminated fabric materials comprising foam layers which are resistant to the passage of noxious chemicals in the form of liquids and condensible vapors and gases, but which are relatively permeable to air and water vapor. Said laminated materials comprise (a) an air and water vapor permeable open cell solid resin foam resistant to passage therethrough of noxious chemicals in liquid or vapor form, said foam having dispersed therein a particulate adsorbent material for said noxious chemicals, said particulate adsorbent material being bonded in said foam by an organic binder which is substantially free from substances which substantially deactivate the adsorbent; and (b) an air and water vapor-permeable fabric backing to which the aforesaid foam is bonded. The foam is preferably polyurethane. Activated carbon is the preferred particulate material. Impregnation of the foam is accomplished by soaking in a suspension of particles in water or solvent. A fluorochemical may be used to treat the foam after impregnation to impart water and oil repellency. Foam thicknesses of 5/64" to 1/8" (1980-3175 μm) are disclosed.

Goto et al., U.S. Patent No. 4,212,733 discloses an oil-water separation filter, which comprises a porous material, e.g. activated carbon particles, a sintered polyethylene powder bonded to a fibrous layer comprising fibers having a fiber diameter of about 5 to about 30 μ. The filter can also contain a fluorocarbon powder. The filters are used to separate oil from water.

Ogino, et al., U.S. Patent No. 4,411,948 discloses an air-cleaning filter element prepared by applying an adhesive agent (pressure sensitive, water sensitive, or heat sensitive) to at least a pair of three dimensionally mesh-structured elastic- flexible webs, disposing evenly an adsorbent material, such as activated carbon, in a size range of 0.5 mm to 10 mm in diameter between said pair of elastic-flexible webs and pressing the same elastic-flexible webs together. The web is made by selective hydrolysis of a polyurethane foam.

Strack et al., U.S. Patent No. 5.681,645 discloses a laminate material made from a nonwoven elastomeric web and at least one web of textile material discontinuously adhesively bonded to each site. The nonwoven elastomeric web is preferably a web of meltblown elastomeric fibers made of e.g. polyurethane and the other webs may be knits, wovens or scrim materials. The web can be a composite web of more than one fiber or of a fiber plus a particle such as an activated carbon.

Yamaguchi et al., U.S. Patent No. 5,945,211 disclose a zinc oxide fine particle-adhered composite material consisting essentially of a substrate and zinc oxide fine particles adhered thereto. The zinc oxide fine particles are firmly adhered to, and are substantially exposed on, the surface of the substrate. The composite material is prepared by, for instance, contacting an acidic aqueous suspension of zinc ions in contact with a substrate and then adding alkali solution to deposit particulate on the surface.

Groeger et al., U.S. 5,972,808 teach a fibrous structure comprising a fibrous matrix with surrogate particles fixed to the fibrous matrix. Functionally active, fine particles are immobilized on the fixed surrogate particles. In this way, Groeger et al. provide the advantages of high surface area provided by fine particles, and solve the issue of how to entrain them effectively in a nonwoven matrix, by attaching them to very large particles that serve no functional purpose except to anchor the fine particles. The surrogate particles have an average diameter in the range of from about 100 micrometers to about 1 mm to 10 mm, and thus provide substantial weight and bulk to the webs of the disclosure. Rosenberg et al., U.S. Patent No. 6,423,123 disclose a fluid filter material in the form of a flat article, comprising a carrier layer and an adsorption layer. The adsorption layer is formed by melt adhesive threads loaded with adsorber particles. Spunbond polyurethane is one material disclosed as forming the thermoplastic matrix, which is the web to a carrier layer. Silicates, zeolites, and activated carbon are preferred particles to be embedded in the adsorption layer.

Minemura et al., U.S. Patent No. 6,746,760 disclose a gas adsorption sheet comprising granular activated carbon with average particle diameter of 60 to 600 μm, a supporting fiber for fixing the granular activated carbon in contact with it, and an adhesive fiber which mainly contributes to shape retention. A method for producing the sheet comprises contacting an aqueous slurry of granular activated carbon, a supporting fiber, and a water-swelling adhesive fiber, then drying the slurry on a cover sheet. The cover sheet can be a woven or nonwoven fabric and are preferably electret-treated.

Kasmark, U.S. Patent No. 6,878,193 disclose a non-shedding light duty fibrous filter material containing activated carbon and/or other sorptive particles has a thickness of 1/8 inch to 3/8 inch (3.18 to 9.53mm) and is composed entirely of low melt fibers of 4 to 15 denier. Polyester fiber is blown along with particles to form a web. Carbon, alumina impregnated with KMnO4, and zeolites are disclosed. More recently, nanofibrous nonwoven webs have been developed. See Chung et al., U.S. Patent No. 6,743,273; Kahlbaugh et al., U.S. Patent No.

5,423,892; McLead , U.S. Patent No. 3,878,014; Barris, U.S. Patent No. 4,650,506; Prentice, U.S. Patent No. 3,676,242; Lohkamp et al., U.S. Patent No. 3,841,953; and Butin et al., U.S. Patent No. 3,849,241; U.S. Patent Publication No. 20050095695, and WO06/094076, all of which are incorporated herein by reference. The nanofiber layer can be an electrospun or meltblown layer formed from fibers having a diameter from about 0.001 to about 2 micrometers or about 0.05 to about 1 micrometer, having a basis weight of about 0.01 to 240 micrograms-cm^"2 and having an average pore size of about 0.1 to 10 micrometers. The nanofiber layer is typically substantially uniformly formed in random orientation and is typically applied on top of and in association with a woven or non- woven fabric substrate layer. The nanofiber layer, having small pore sizes, can act as a barrier to aerosols, or, using its hydrophobic nature, repel liquid agents. Nanofiber filter media have fueled new levels of performance in air filtration in commercial, industrial and defense applications where efficiency requirements have been low in comparison to HEPA (High Efficiency Particle Air) or ULPA (Ultra Low Penetration Air) levels. Recent advancements in the nanofiber enhanced filtration field have extended the usability of nanofibers into applications with higher filtration efficiencies. In particular, these nanofiber matrices provide comparable performance to other commercially available HEPA media composed of sub- micrometer glass or expanded-PTFE membranes. Such performance is shown along with benefits of the technology. Nanofiber filter media is a viable solution in high efficiency applications with strict performance requirements. Nanofibers have also been used in protective garments, as aerosol barriers.

For example, See Gogins et al., U.S. Patent Publication No. 2004/0116025, which is incorporated herein by reference. However, the aerosol barrier garments of the prior art do not provide a means to securely hold active particles having a small particle size securely within the nanofiber network. Thus, the barrier properties of the fabrics are limited to the barrier properties of the nanofiber network itself; while particles can be incorporated, this is done by incorporating a separate layer having particles that is disposed between the nanofiber layer and the fabric layer. No means to incorporate particles securely within the nanofiber network is disclosed.

There is a need to provide protective textiles that incorporate active particles to provide good barrier properties toward hazardous substances, particularly toward more than one hazardous substance, and more particularly toward one or more hazardous substances having different chemical and physical properties, and even more particularly toward one or more hazardous substances that are biological and non-biological in nature. Further, there is a need to provide protective textiles that contain particles, such as those that contain carbon, that do not suffer from high weight, significant particle loss or shedding, particle shifting, and particle crushing. Still further, there is a need to provide protective textiles that are lightweight and soft, with good air permeability, which are thereby comfortable to wear in garment applications.

Still further, there is a need to provide protective textiles that are suitable for the specialized coatings and coating processes that are frequently needed in the various application areas for said textiles. Examples of such coatings include, for example, low reflectance, low retroreflectance, and other camouflage coatings for military garments, and flame retardant coatings for first responder garments and permanent or portable safety shelters. Still further, there is a need to provide protective textiles with superior properties like those mentioned above, that are additionally inexpensive to manufacture.

Summary of the Invention Disclosed herein are protective air permeable multilayer textile composites, production thereof, and use thereof, which improve upon one or more of the aforementioned problems associated with the protective textiles of the prior art.

While protective textiles containing particles or particulates that are sorbing or reactively decomposing toward hazardous substances are known, we have discovered that they can be made more quickly and efficiently sorbing or reactive when they are incorporated into a web of elastomeric nano fibers. This is accomplished by using the nanofibers to incorporate active particles having a very small particle size, which increases surface area and thus sorb and/or react faster and with greater efficiency than past constructions. The use of an elastomer to form the nanofibers is a key aspect of providing small particles that are securely held in the nanofiber network.

A variety of methods can be utilized for the manufacture of nanofiber. Chung et al., U.S. Patent No. 6,743,273; Kahlbaugh et al., U.S. Patent No. 5,423,892; McLead , U.S. Patent No. 3,878,014; Bams, U.S. Patent No. 4,650,506; Prentice, U.S. Patent No. 3,676,242; Lohkamp et al., U.S. Patent No. 3,841,953; and Butin et al., U.S. Patent No. 3,849,241; U.S. Patent Publication No. 20050095695, and WO06/094076, all of which are incorporated by reference herein, disclose a variety of fine fiber or nanofiber technologies. The nanofiber of the invention is typically electrospun onto a substrate. The substrate can be pervious or impervious. Electrospinning techniques are exemplified in Chung et al., U.S. Patent Nos. 7,070,640, 6,924,028, 6,955,775, and 7,090,715; U.S. Patent Publication Nos. 2006/0117730 and 2007/0012007; and pending U.S. Patent Application Nos. 11/398,922, 11/331,555, 11/398,788, and 11/592,402, all of which are incorporated herein by reference.

The invention provides a nonwoven nanofiber web from which can be generated protective clothing fabrics. The webs of the invention are composite webs comprising a substantially continuous elastomeric nanofiber with a fiber diameter of about 2 micrometers or less, and at least one type of active particle having a particle size of about 200 micrometers or less, wherein the composite web has air permeability of about 0.1 to 100 fpm and a basis weight of 5-500 g/m². When the composite web is provided on a fabric substrate, there is sufficient adhesion of the particles to the nanofiber to result in total weight loss of 10 wt% or less, based on the weight of the composite web, as measured by the ASTM F 392 condition B, Standard Test Method for Flex Durability of Flexible Barrier Materials. Further, when the composite web is provided on a fabric substrate as the inner layer, the nanofiber web provides a soft, comfortable feel with good drape and is lightweight. When the characteristics of permeability, softness, drape, and weight are combined with its durability, fabrics having provided thereon the composite webs of the invention are ideally suited for protective garment applications.

The composites of nanofibers and active particles can act in concert to provide protection against radiation, aerosolized chemical, agents, and biological agents. The active particles can absorb, adsorb, deflect, and/or deactivate electromagnetic, gaseous or liquid chemical or biological agents and toxins from the ambient atmosphere. A variety of active chemical treatment materials and adsorbents or absorbents can be provided in the composite webs of the invention. The nonwoven nanofiber composite webs of the invention are formed by providing an elastomeric polymer to generate the nanofiber. The elastomeric polymer entrains the active particles and, when flexed, does not tend to shed particles; thus, the effective adhesion of particles in the elastomeric nonwoven nanofiber composite webs is surprisingly high. Additionally, the nonwoven elastomeric nanofiber composite web can entrain particles of a relatively small size compared to traditional nonwoven webs, because of its small pore size. Thus, an advantage of the nonwoven elastomeric nanofiber composite webs of the invention is that higher available particle surface area is provided than for other nonwoven webs wherein particles are entrained. We have discovered that the rates and efficiencies of sorption and reactivity each increase with decreasing particle or particulate size and with decreasing electrospun fiber thickness.

While the elastomeric nanofiber composite webs of the invention can provide superior barrier/filtration properties as standalone webs, it is preferable to include the webs on a substrate. The substrate can comprise, for example, an expanded PTFE layer or Teflon^® layer. Such layers are useful in a variety of applications that can provide both filtration and activity from the active particulate. The substrate can also be a nonwoven, e.g. a filter layer such as a dust mask substrate or a depth filter. Preferably, the substrate is a garment fabric. The elastomeric nature of the nanofiber web is particularly well suited to the flexing, stress, and strain commonly encountered in garment applications. To make a garment fabric, one or more composite web layers can be disposed on top of a traditional garment type fabric, such as canvas or denim. When provided in such an arrangement, multilayer fabrics of the invention have the following preferred properties: (1) increased aerosol protection; (2) adequate air permeability; and (3) absorbent, adsorbent, and/or biocidal filtration capability, and (4) durability to the flexing and abrasion expected in garment use, especially military garment use, without substantial particle shedding.

Advantageously, due to the use of an elastomeric nanofiber nonwoven, the puncturing by needles encountered when sewing a protective garment does not create as much damage to the web as such a breach does for non-elastomeric nonwoven webs used in prior art protective garments.

One major benefit of the invention is that lighter and/or thinner protective textiles compared to traditional nonwoven protective, particulate bearing layers can be produced by virtue of the elastomeric nonwoven nanofiber composite webs of the invention. Advantageously, because of the very fine fibers of the nanofiber nonwoven, very small particle sizes can be durably retained and the fibers pose less interference to particles or particulates of all sizes that are contained therein better than textile webs comprised of fibers of larger fiber thickness. However, due to the high degree of porosity realized in electrospun nano fiber webs, permeability of the webs remains high. Thus, a high degree of particle surface area can be made available for rapid absorption, adsorption, deflection, and/or reaction as harmful substances are encountered. Additionally, a relatively large amount of particles can be provided in the elastomeric nonwoven nanofiber composite webs of the invention without incurring discomfort in the wearer due to abrasion from the particles or heaviness due to large amounts of large particles that would otherwise be required to accrue sufficiently effective surface area.

Further, we have discovered a valuable new phenomenon in the transport science of protective textiles where higher degrees of comfort, in the form air permeability and moisture transport, and higher degrees of protection, in the form of sorption and reactive decomposition, can be achieved by making some of the components of a textile layer, such as certain of the fibers or particles or particulates contained therein for example, relatively more wetting, wicking, gelling, or dissolving toward one or more hazardous substances than toward water and by making certain other of the components of the textile layer relatively more wetting, wicking, gelling, or dissolving toward water than toward one or more hazardous substances.

Further, we have found that multiple hazards are easily addressed by including multiple elastomeric nonwoven nanofiber composite webs in the fabrics of the invention. Thus, in addition to providing for multiple types of particles in one such composite layer, different particle types can also be included in different composite web layers. hi addition to these distinguishing characteristics, fabrics made using the elastomeric nonwoven nanofiber composite webs of the invention are very lightweight compared to particle filled barrier or filtration webs used for such applications in the past. Further, the elastomeric nonwoven nanofiber composite webs have a surprisingly soft hand. Thus, the fabrics are superior from the particle containing fabrics of the prior art from a comfort standpoint when the fabrics are incorporated into garments.

We have found additional advantages of the composite webs of the invention over webs or membranes formed from PTFE, which are the basis for many of the prior art chemical barrier articles. For example, the composite webs of the invention can be incinerated with a much lower release of toxins versus PTFE-based materials. This attribute is advantageous for contaminated garment disposal and casualty bags. Further, when used in a garment application, the composite webs of the invention are much quieter than sintered PTFE materials when a person wearing the garment moves in a normal way, e.g. walking, running, etc. Thus, barrier efficiency protection is offered without a trade-off in noisiness / crinkliness. In military applications this attribute is especially desirable.

Finally, we have discovered several inexpensive processes to prepare the composite webs of the invention. One of these processes involves projecting a dope of the fiber forming medium and the particles or particulates from a common source onto a substrate such as a textile, foam, or membrane, while another process involves projecting one or more kinds of particles, one or more kinds of fiber forming media, or mixtures thereof, each from an independent source onto a substrate. In this second process, controllable, complex, valuable electrospun multilayer arrangements of different fibers, particles or particulates, and fiber-to- particle or particulate loadings can be conveniently obtained.

Brief Description of the Drawings

FIG. 1 is a side view of a schematic depiction of a multilayer textile composite;

FIG. 2 is a side view of a schematic depiction of a multilayer textile composite comprising a shell;

FIG. 3 is a side view of a schematic depiction of a multilayer textile composite comprising two membrane layers; FIG 4 is a side view of a schematic depiction of a multilayer textile composite comprising two active layers;

FIG. 5 A is a micrograph top view of a multilayer textile composite at 100Ox magnification;

FIG. 5B is a micrograph top view of a multilayer textile composite at 300x magnification;

FIG. 6A is a side view of the multilayer textile composite depicted in FIGURES 5 A and 5B at 100Ox magnification; FIG. 6B is a side view of the multilayer textile composite depicted in FIGURES 5 A and 5B at 10Ox magnification;

FIG. 7 A is a micrograph top view of a multilayer textile composite at 100Ox magnification after flux testing; FIG. 7B is a micrograph top view of a multilayer textile composite at 30Ox magnification after flux testing;

FIG. 8 A is a micrograph side view of the multilayer textile composite after flux testing depicted in FIGURES 7A and 7B at 50Ox magnification;

FIG. 8B is a micrograph side view of the multilayer textile composite after flux testing depicted in FIGURES 7A and 7B at 20Ox magnification;

FIG. 9 A is a top view photograph of sample EX-I after flux testing; FIG. 9B is a top view photograph of sample EX- 15 after flux testing; FIG. 9C is a top view photograph of sample EX- 16 after flux testing; FIG. 9D is a top view photograph of sample EX- 17 after flux testing; FIG. 9E is a top view photograph of sample EX- 18 after flux testing;

FIG. 9F is a top view photograph of sample EX- 19 after flux testing; FIG. 9G is a top view photograph of sample EX-20 after flux testing; FIG. 1OA is a micrograph bottom side view of a sample EX-I comprising a substrate on its bottom side at 50x magnification; FIG. 1OB is a micrograph bottom side view of a control sample comprising a substrate on its bottom side at 50x magnification;

FIG. 1OC is a micrograph bottom side view of a sample EX-I comprising a substrate on its bottom side at 10Ox magnification;

FIG. 1OD is a micrograph bottom side view of a control sample comprising a substrate on its bottom side at 10Ox magnification;

FIG. 1OE is a micrograph bottom side view of a sample EX-I comprising a substrate on its bottom side at 20Ox magnification; and

FIG. 1OF is a micrograph bottom side view of a control sample comprising a substrate on its bottom side at 20Ox magnification.

Detailed Description of the Invention

Several general embodiments of the multilayer textile composites are depicted in FIGURES 1 through 4. The multilayer textile composites depicted in FIGURE 1 comprises an active layer 1 comprising electrospun nonwoven fibers 2 of same or different chemical composition contacting particles or particulates 3, all or a percentage of which are either sorptive, reactively decomposing, or both sorptive and reactively decomposing towards one or more hazardous substances; and fibrous, foam, or membrane layer 4. Interface 11 between layers 1 and 4 can be sharp or can have varying degrees of interpenetration. The multilayer textile composites of this general embodiment could be fabricated into protective devices, systems, or articles, such as a garments, masks, filters, or tents for example, wherein active layer 1 faces the exposed side of said devices, systems, or articles and can either come into direct or indirect contact with hazardous substances.

In some situations, such as when multilayer textile composites of this general embodiment are fabricated into military garments intended for service in desert or woodland areas for example, it is preferred that active layer 1 be shielded from exposure to weathering or abrasive elements. Preferred examples of protective articles where active layer 1 of the multilayer textile composites come into indirect contact with hazardous substances describe further general embodiments of this invention. Such an embodiment is depicted in FIGURE 2. A multilayer textile consisting of fibrous, foam, metallic, porous metallic, or membrane shell 5 which comes into direct contact with hazardous substances. Said shell 5 can be optionally secured to active layer 1 or through active layer 1 to fibrous, foam, or membrane layer 4 by any convenient means such as by sewing, gluing or, in particular, by laser welding in a manner that forms one or more seams, seals, or connections 6 and one or more air gaps 7 between active layer 1 and shell 5. When such a protective article containing air gaps 7 is employed in warm weather protective garments or in tents, for example, then it is usually preferred that the one or more air gaps 7 exist in fluid communication with one or more exterior vents where the garment or tent can be designed with a means of closing said vents or diverting or directing them away from any hazardous substance threats whenever they can be encountered. It has been discovered that providing for air gaps and appropriately placed vents in this manner provide both a high degree of comfort as well as additional protection against hazardous substances which can enter the gap through shell 5, particularly when the air is actively flushed through the system with the aid of an active electronic or mechanical blower. Additional general embodiments of this invention are the multilayer textile composites depicted in FIGURE 3, comprising active layer 1 comprising electrospun nonwoven fibers 2 of same or different chemical composition contacting particles or particulates 3, all or a percentage of which are either sorptive, reactively decomposing, or both sorptive and reactively decomposing towards one or more hazardous substances; fibrous, porous metallic, or membrane layer 8; and optional fibrous, foam, or membrane layer 4. Interface 12 between layers 1 and 8 can be sharp or can have varying degrees of interpenetration, and interface 11, between layers 1 and 4, if it exists, can be sharp or can have varying degrees of interpenetration. One convenient means of manufacturing a bilayer textile composite of this embodiment where it is desired that layer 8 be fibrous and interface 12 be interpenetrating is to provide for a continuous translating web of the material of layer 8, a first zone where the web contacts a raking, disruption, or beater comb or roller, and additional zones where the web is covered with the electrospun fibers and the particles or particulates by their projection from common or independent sources.

One convenient means of manufacturing a trilayer textile composite of this embodiment where it is desired that layer 8 be fibrous, interface 12 be interpenetrating, layer 4 be a membrane, such as a hydrophobic microporous membrane for example, and interface 11 be relatively sharp is to provide for the same web manufacturing line described above but with the additional steps of providing for optionally calendaring the bilayer, followed by coating the layer 1 side of the bilayer with a solution of polysulfone in a dipolar aprotic solvent, such as a ten weight percent solution of polysulfone in dimethylacetamide for example, using a knife over drum coater for example, followed by quenching the web in a solvent for the DMAC yet a nonsolvent for the polysulfone, such as water for example, followed by optionally drying the resulting trilayer composite in an oven. Ordinarily, the multilayer textile composites of these general embodiments could be fabricated into protective devices, systems, or articles, such as garments, masks, filters, or tents for example, where fibrous, porous metallic, or membrane layer 8 comes into direct contact with hazardous substances. In some cases it can be desirable to incorporate certain desirable functional chemicals or coatings to layer 8, examples include camouflage coatings; infrared absorbing coatings; water and oil repellant coatings which provide protection against the elements and certain industrial residues and can also provide additional barrier protection toward certain hazardous substances; fire resistant coatings, such as Preflam 8106, for example, available from the Pymag Corporation; and antimicrobial coatings which provide additional barrier protection toward bacterial hazardous substances.

While active layer 1 can be made to have any sufficient thickness in order to provide for good sorbing or reactively decomposing protective action toward hazardous substances, we have discovered that the byproducts of some decomposed hazardous substances are in some cases also hazardous, and so, in still further generalized embodiments of this invention, we conveniently prepared the multilayer textile composites depicted in FIGURE 4 having more than one active layer 1 and 1' where the particles or particulates present in layers 1 and 1' can also be reactively decomposing toward any byproducts of hazardous substances and where the interface 13, if it exists, between optional fibrous, foam, or membrane layer 4 and active layer 1' can be sharp or can have varying degrees of interpenetration and where the interface 14 between active layers 1 and 1' can be sharp or can have varying degrees of interpenetration.

The webs of the invention are composites of nonwoven elastomeric nanofibers 2 and active particles 3. Specifically, the nonwoven webs employ substantially continuous, elastomeric nanofibers 2, wherein the term "nanofiber" is defined as a nonwoven fibrous web comprising fibers having a fiber diameter of about 2 μm or less, and at least one type of active particle having a particle size of about 500 μm or less, wherein the term "active particles" means particles that adsorptive, absorptive, deflecting, and/or chemically reactive toward electromagnetic radiation, gaseous or liquid chemical agents, and/or biological agents. The term "adsorptive" indicates a particle that is active to adsorb and accumulate material from a fluid stream on the surface of a particle. The term "absorptive" indicates that the particle has the capacity to accumulate material from a fluid stream into the interior or void space or spaces within a particle. "Chemically reactive" indicates that the particulate has the capacity to react with and chemically change both the character of the particle and the chemical character of the material contacted by the particle. The elastomeric nonwoven nanofiber composite web has permeability to air of about 0.1 fpm to about 100 fpm to provide for breathability when incorporated into garment applications. A key feature of the composite web is that the particles, having small particle size, are effectively held in the web by virtue of the nanofiber web; thus, when mounted on a fabric substrate and subjected to flex durability testing per ASTM F 392 condition B, Standard Test Method for Flex Durability of Flexible Barrier Materials, the total weight loss is 10 wt% or less, based on the original weight of the composite web, preferably less than 5 wt% of the original weight of the composite web, and most preferably less than lwt% of the original weight of the composite web. Despite the high level of permeability, the elastomeric nonwoven nanofiber composite webs of the invention can be highly efficient as aerosol barriers. Preferably, the elastomeric nonwoven nanofiber composite webs of the invention have aerosol filtration efficiency of at least about 30 to 99.9999 percent for 0.3 micrometer sized particles, as determined in an aerosol efficiency test at 10.5 fpm face velocity. This test is described more fully in the Experimental section.

The elastomeric nonwoven nanofiber composite webs of the invention preferably comprise nanofiber at about 5-95 wt% based on the total weight of the web, more preferably 20-50 wt% based on the total weight of the web. Active particles are preferably present in the composite web at about 5-95 wt% based on the total weight of the web, more preferably at 50-80 wt% based on the total weight of the web.

The composite webs of the invention are preferably about 5-1000μm in average thickness, more preferably about 50 to 250 μm average thickness. The webs have a basis weight that is preferably about 5-500 g/m², more preferably about 10-100 g/m². As used herein, "basis weight" is a measure of the density of a web or a fabric, expressed in terms of the measured weight, in grams, of a square meter of the web or fabric. The composite webs of the invention are surprisingly soft for a nonwoven, particulate bearing web. Preferably, when placed on a fabric substrate, the composite webs of the invention have a stiffness of about 1 mg/cm to 1000 mg/cm as measured by the Shirley Stiffness test, ASTM D412, more preferably 10 mg/cm to 250 mg/cm. The composite webs of the invention employ elastomeric fibers. The fibers can be naturally derived elastomeric materials such as elastin or resilin for example, or they can be synthetic elastomers such as polyisoprene, polyisobutylene, polybutadiene, ethylene- vinyl acetate polymer, halobutyl rubber, styrene-butadiene polymer, hydrated butadiene-styrene copolymer, polychloroprene, ethylene- propylene copolymer, ethylene-propylene-diene copolymer, epichlorohydrin rubber, polyacrylic rubber, silicone rubber, fluorosilicone rubber, fluoroelastomer, tetrafluoroethylene-propylene rubber, chlorosulfonated polyethylene, polyester elastomer, polyurethane elastomer, polyether-amide block elastomer, polysulfide rubber, or copolymers or mixtures thereof, or a mixture of one of the above with a nonelastomeric polymer, or mixtures of synthetic and nonsynthetic elastomers, or mixtures of synthetic and nonsynthetic elastomers with a nonelastomeric polymer. Preferably, the elastomer is a polyurethane.

An advantageous aspect of the invention is that the elastomeric nonwoven nano fiber composite webs effectively entrain particles securely, so that they do not "shed" or settle out of the web; yet the network is still very air permeable and therefore breathable for garment applications. Without being limited to theory, we believe that both the small effective pore size created by the nanofibrous network in conjunction with the high overall percent porosity afforded by the nanofiber diameter work with the elastomeric nature of the web to hold particles in the web more securely than webs of the prior art. The elastomeric nature of the web allows elastic recovery of the web after stress and strain instead of permanent deformation or even breakage of fibers. The elastomeric material(s) chosen to form the webs of the invention preferably have an elongation at break of about 200-2000% as measured using ASTM-D412. More preferably, the elongation at break is about 500-1500%. The elastomeric material(s) chosen to form the webs of the invention preferably have a tensile strength at 100% elongation of about 10-1000 psi as measured using ASTM-D412. More preferably, the tensile strength at 100% elongation is about 300-700 psi. Active particles 3 can be composed of chemically same or different entities and can have various shapes and internal and external surface areas. The particles are active in that they are chemically absorbent, chemically adsorbent, chemically reactive, biologically reactive, or a mixture of any of these. However, the webs of the invention can further comprise particles that are not active as defined above, for example spacer particles that serve to maintain open pores and/or a spacing between the nanofiber web and the substrate upon which the web is disposed. Additionally, active particles can also function as spacer particles, depending on their size and shape and the size and shape of other particles loaded into the web, and how the web is used, e.g. as a layer on a fabric or some other substrate, or standing alone.

Particles useful in the invention can be active due to the inherent properties of the particulate material. For example, alumina particles are well known as reactive towards a number of hazardous compounds. As such, they are one of the preferred types of active particles that can be used in embodiments of the invention. However, particles can also be used as a substrate upon which reactive or absorptive materials are provided, that can further provide a benefit by, for example, decomposing hazardous chemicals. For example, alumina or titania formed in situ inside the pores of activated carbons can be used to catalytically convert compounds and reduce or eliminate hazardous substances. Thus, a carbon particle with adsorbed titania is both adsorptive and reactive, due to having pores for adsorption of chemicals and titania to catalyze chemical reactions inside the pores of the carbon particle.

The particles that are useful in the composite webs of the invention can be up to 1000 micrometers in average particle size; however, smaller particles are advantageous because they offer larger surface area in general and, even at very small particle sizes, are well secured in the nanofiber network. Thus, even for small particles, aspect ratio can range between about 1:1 to 1:100 without losing appreciable amounts of particles from the nanofiber web. As mentioned above, it can be advantageous to include more than one type of particle in the webs of the invention. Thus, a biologically active particle and a chemically absorptive and/or reactive particle can be incorporated into the elastomeric nanofiber composite webs of the invention and the web incorporated into a protective garment for military purposes, e.g. where chemical, biological, or both types of agents can be deployed during wartime.

Several nonlimiting examples of reactive particles, and other nonparticulate materials that are reactively decomposing toward hazardous substances and that can be impregnated into or sorbed onto the surface of particles, include polyoxometalates, alumina powders, granules, and shaped monoliths, and calcium oxide, or compounds covalently bonded to silica colloids or agglomerates or other glass particles. For entities that are reactively decomposing toward hazardous substances, particles (either particles or particles having reactive material adsorbed thereon) can range in size from about 0.01 to 1000 micrometer. Preferably the particle size is 500 micrometers or less, more preferably the size of the particles is about 300 micrometers or less, still more preferably the size of the particles is about 200 micrometers or less, and most preferably the size of the particles is 100 micrometers or less. It is preferred that the particles have a surface area from about 100 m²/g to 2000 m²/g. Such particles can be advantageously incorporated into the webs of the invention either alone or in combination with any other particles such as those mentioned herein.

A particle can also be absorptive or adsorptive without inducing a chemical reaction. Several nonlimiting examples of adsorbing entities include synthetic and natural zeolites, layered minerals, and activated carbon powders, granules beads, and shaped monoliths. For those entities that are sorbing toward hazardous substances, particles can range in size from about 0.01 to 1000 micrometer. Preferably the particle size is 500 micrometers or less, more preferably the size of the particles is about 300 micrometers or less, still more preferably the size of the particles is about 200 micrometers or less, and most preferably the size of the particles is 100 micrometers or less. It is preferred that the particles have a surface area from about 100 m²/g to 2000 m²/g, more preferably the surface area is between about 1200 m²/g to 2000 m²/g. Such particles can be advantageously incorporated into the webs of the invention either alone or in combination with any other particles such as those mentioned herein. Additionally, the particles can be further treated with an agent that modifies the adsorption or absorption properties of the particle, rendering the particle e.g. more hydrophilic or hydrophobic, depending on the end application and the types of chemicals to be adsorbed or absorbed.

It has been discovered that it is most preferable to incorporate entities that are both sorbing and reactively decomposing toward hazardous substances into active particles 3 when the multilayer textile composite will be used in applications involving hazardous compounds that are slow to decompose. Several nonlimiting examples of entities that are both sorbing and reactively decomposing toward hazardous substances include layered minerals partly filled with sodium chlorite, agglomerations of alumina and activated carbon, and in some cases alumina, particularly when hazardous substances are polar molecules. For those entities that are both reactively decomposing and sorbing toward hazardous substances, particles can range in size from about 0.01 to 1000 micrometers, preferably less than 500 micrometers. Preferably the particles possess a surface area of at least about 500 m²/g and it is especially preferred that the entity be partly comprised of activated carbon. An exemplary means of producing an entity that is both sorbing and reactively decomposing toward hazardous substances is to impact nanometer-scale reactively decomposing particles, such as alumina for example, onto larger activated carbon beads. Such particles can be advantageously incorporated into the webs of the invention either alone or in combination with any other particles such as those mentioned herein.

Additionally, active particles useful in the invention can be metal organic frameworks (MOFs) and covalent organic frameworks (COFs). MOFs and COFs are solid-state porous structures in which pore size and functionality can be varied systematically. MOFs and COFs are reactive and adsorptive active particles that can be utilized to react with and adsorb hazardous compounds to reduce and/or eliminate hazardous compounds. Further, the MOFs and COFs can be utilized as reactive spacer particles.

The elastomeric nonwoven nanofϊber composite web or webs allow the MOFs and COFs to be utilized without shaping bodies for containing the MOFs and COFs. The MOFs and COFs are held in the elastomeric nonwoven nanofϊber composite web or webs of the active layer 1. Therefore, the shaping of bodies for containing the MOFs and COFs is unnecessary in the present invention.

The MOF can comprise MOF-O, MOF-2, MOF-3, MOF-4, MOF-5, MOF- 38, MOF-31, MOF-12, MOF-20, MOF-37, MOF-8, MOF-9, MOF-69A, and MOF- 69B. This list is not restrictive. It is appreciated that any suitable MOF can be utilized without departing from the scope and intent of the present disclosure. For example, the MOF can be any of the MOFs disclosed in U.S. Patent 6,893,564, filed May 30, 2002 and issued May 17, 2002 and U.S. Patent 7,196,210, filed May 2, 2005 and issued March 27, 2007, which are herein incorporated by reference in their entirety. The COF can comprise COF-102, COF-103, COF-105, and COF-108. This list is not restrictive. It is appreciated that any suitable COF can be utilized without departing from the scope and intent of the present disclosure. For example, the COF can be any of the COFs disclosed in H. El-Kaderi et al., Science, 316 (2007) p. 2638-272, which is herein incorporated by reference in its entirety.

The MOF can be an iso-reticular Metal-Organic Framework (IRMOF). It is understood that any suitable IRMOF can be utilized without departing from the scope and intent of the present disclosure. For example, the IRMOF can be any of the IRMOFs disclosed in U.S. Patent 7,196,210 filed May 2, 2005, which is herein incorporated by reference in its entirety.

U.S. Patent 6,893,564, filed May 30, 2002 and issued May 17, 2002; U.S. Patent 7,196,210, filed May 2, 2005 and issued March 27, 2007; H. El-Kaderi et al., Science, 316 (2007) p. 2638-272; B. Hoskins and R. Robson, J. Am. Chem. Soc, 112 (1990) p. 1546-1554; and J. Fournier, J. Am. Chem. Soc, 125 (2003) p. 1002-1006 disclose various MOFs, COFs, and/or IRMOFs and/or the processes or methods for forming the MOFs, COFs, and/or IRMOFs and are incorporated herein by reference in their entirety. These references are not limiting. Any suitable known MOF, COF, and IRMOF and method for making thereof can be utilized without departing from the scope and intent of the present disclosure. Nonlimiting examples of hazardous substances advantageously absorbed, adsorbed, or chemically reacted include toxic industrial chemicals (TICs), such as 1,2-dimethylhydrazine, 2,2'-iminodiethylamine, 2-chloroethanol, 2-ethoxyethyl acetate, 3-chloropropane-l,2-diol, acetone cyanohydrin, acrolein, acrylonitrile, allyl alcohol, allyl amine, allyl chlorocarbonate, allyl isothiocyanate, alpha-methyl benzyl alcohol, ammonia, arsenic trichloride, arsine, boron tribromide, boron trichloride, boron trifluoride, bromine, bromine chloride, bromine pentafluoride, bromine trifluoride, carbon disulfide, carbon monoxide, carbonyl fluoride, carbonyl sulfide, chlorine, chlorine pentafluoride, chlorine trifluoride, chloroacetaldehyde, chloroacetone, chloroacetonitrile, chloroacetyl chloride, chlorosulfonic acid, crotonaldehyde, cyanogen, diborane, diethylenetriamine, diketene, dimethyl sulfate, diphenylmethane-4,4'-diisocyanate, epichlorohydrin, ethyl chloroformate, ethyl chlorothioformate, ethyl phosphonous dichloride, ethylene dibromide, ethylene oxide, ethyleneimine, ethylphosphonothioicdichloride, fluorine, formaldehyde, hexachlorocyclopentadiene, hydrazine, hydrogen bromide, hydrogen chloride, hydrogen cyanide, hydrogen fluoride, hydrogen iodide, hydrogen selenide, hydrogen sulfide, iron pentacarbonyl, isobutyl chloroformate, isopropyl chloroformate, isopropyl isocyanate, methanesulfonyl chloride, methyl bromide, methyl chloroformate, methyl chlorosilane, methyl hydrazine, methyl isocyanate, methyl mercaptan, N-butyl chloroformate, N-butyl isocyanate, nitric acid, nitric oxide, nitrogen dioxide, N-propyl chloroformate, Parathion, perchloromethyl mercaptan, phosgene, phosphine, phosphorus oxychloride, phosphorus pentafluoride, phosphorus trichloride, sec-butyl chloroformate, selenium hexafluoride, silicon tetrafluoride, stibine, sulfur dioxide, sulfur trioxide, sulfuric acid, sulfuryl chloride, sulfuryl fluoride, tellurium hexafluoride, tert-butyl isocyanate, tert-octyl mercaptan, tetraethyl lead, tetraethyl pyrophosphate, tetramethyl lead, titanium tetrachloride, toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, trichloroacetyl chloride, trifluoroacetyl chloride, and tungsten hexafluoride. Other examples of hazardous materials can also be found in household, institutional, trade, and sanitation products, such as disinfectant surface cleaning compositions, glues, epoxy floor finishing compositions, drain opening compositions, farm and ranch animal dips, poultry disinfectants, depilatories, and hair straightening compositions, for example. Still other examples of hazardous materials include chemical warfare (CW) agents, nonlimiting examples of which include blood agents such as cyanogen chloride (CK) and hydrogen cyanide (AC); blister agents such as Lewisite (L), sulfur mustards (HD, H, HT, HL, HQ), and nitrogen mustards (HNl, HN2, HN3); G-nerve agents, such as Tabun (GA), Sarin (GB), Soman (GD), Cyclosarin (GF), and GV; V- nerve agents, such as VE, VG, VM, VX, and Novichok agents; and pulmonary agents, such as chlorine, chloropicrin (PS), phosgene (CG), and diphosgene (DP); and incapacitating and riot control agents, such as Agent 15 (BZ) and KOLOKOL-I, pepper spray (OC), CS gas, CN gas (mace), and CR gas.

Biologically active, or bioactive, particles can also be incorporated into elastomeric nonwoven nanofiber composite webs of the invention for the purpose of deactivating hazardous airborne biological materials when incorporated into protective garments, among other applications. The biologically active particulate of the invention can comprise an inert particulate coated with or otherwise attached to a cell, microorganism, enzyme or bioactive molecule, or combined with an active or bioactive particulate such as cells, enzymes, proteins, and the like, or mixtures thereof. Preferably, the bioactive material is cellulytic or cytotoxic. Bioactive particles can also comprise chemicals that are not themselves biological in nature, but are known to deactivate, or lyse, biologically hazardous biological material.

Nonlimiting examples of hazardous biological materials include biological warfare (BW) agents such as Anthrax, Botulinum Toxins, Brucellosis, Cholera, Clostridium Perfringens Toxins, Congo-Crimean Hemorrhagic Fever, Ebola Haemorrhagic Fever, Melioidosis, Plague, Q Fever, Ricin, Rift Valley Fever, Saxitoxin, Smallpox, Staphylococcal Enterotoxin B, Trichothecene Mycotoxins,

Tularemia, and Venezuelan Equine Encephalitis, for example; dusty warfare agents; infectious diseases, such as avian influenza, bovine spongiform encephalopathy (Mad cow disease) and variant Creutzfeldt- Jakob disease (vCJD), campylobacteriosis, Chagas disease, cholera, cryptococcosis, cryptosporidiosis (Crypto), cyclosporiasis, cysticercosis, dengue fever, diphtheria, Ebola hemorrhagic fever, Escherichia coli infection, group B streptococcal infection, hantavirus pulmonary syndrome, hepatitis C, hendra virus infection, histoplasmosis, HIV/AIDS, influenza, Lassa fever, legionnaires' disease (legionellosis), Pontiac fever, leptospirosis, listeriosis, Lyme disease, malaria, Marburg hemorrhagic fever, measles, meningitis, monkeypox, MRSA (Methicillin Resistant Staphylococcus aureus}, Nipah virus infection, norovirus (formerly Norwalk virus) infection, pertussis, plague, polio (poliomyelitis), rabies, Rift Valley fever, rotavirus infection, salmonellosis, SARS (severe acute respiratory syndrome), shigellosis, smallpox, sleeping sickness (Trypanosomiasis), tuberculosis, tularemia, valley fever (coccidioidomycosis), VISA/VRSA - Vancomycin-Intermediate/Resistant

Staphylococcus aureus, West Nile virus infection, and yellow fever, for example; and hazardous medical or veterinary substances, compounds, and compositions, such as infectious human and animal bodily fluids and detritus, and toxic therapeutic compositions, for example. Another type of active particle is a particle that can deflect electromagnetic radiation. Such particles can also be incorporated into the elastomeric nonwoven nano fiber composite webs of the invention. For example, lead and tungsten are known to effectively deflect harmful electromagnetic radiation such as x-rays and gamma rays. Small particles of these metals can advantageously be incorporated into the webs of the invention instead of, or along with, any other particles such as those mentioned elsewhere herein. Other such particles that are useful to deflect or absorb the products of radiation, for example protons or neutrons, can be envisioned without particularly limiting the types of particles or materials that can be incorporated into the webs of the invention.

Particulates which do not necessarily possess sorbing or reactively decomposing properties can be incorporated into the elastomeric nonwoven nano fiber composite webs of the invention along with active particles in order to impart additional attributes. For example, particle or particulate entities can be incorporated to provide spacing or scaffolding between nanofibers 2 in order to increase or maintain the air permeability of the active layer or in order to increase the resistance of the active layer to compaction or crushing when the multilayer textile composite is subjected to compressive forces. Also for example, particles or particulate entities, such as hydrophobic beads for example, can be incorporated in order to promote the spreading or condensation of hazardous organic substances within the active layer and entities such as hydrophilic beads for example can be incorporated in order to promote water or water vapor transport through the active layer. Such particles can be advantageously incorporated into the webs of the invention in addition to any other particles such as those mentioned herein.

In addition to the functions set forth for the composite webs of the invention, an additional variety of additional highly desirable chemically-based attributes can be imparted to the webs. Such functionality can be provided by loading the particulates, particularly absorptive type particulates, with chemical agents designed to be released or employed during the end use of the web; alternatively, they can be impregnated into the web itself and not specifically entrained in particles. Examples of such chemically-based attributes include chemicals for human scent masking in military garment applications; flame retardation in firefighting, first responder, and construction textile applications; insect repellency; water repellency or oil repellency for rain-proof or oil-proof garments; antimicrobial, antiviral, or antifungal agents; or binding agents to provide added adhesion to the particles under some conditions. The method involves incorporating the chemical components into active particles 3 or generally into the web 1. Preferably, agents can be incorporated into the particles 3. For example, carbonate salts such as ammonium carbonate particles and particulates provide flame retardation properties and also serve to reactively decompose a variety of hazardous substances. Such materials can be included in the webs of the invention along with the active particles, or incorporated into the active particles.

It should be understood that the active particles incorporated into the composite webs of the invention are effective in providing additional functionality to the functionality inherently possessed by the nanofiber web itself. As described above and elsewhere, nanofiber webs are by themselves effective aerosol barriers that serve to prevent many hazardous materials from breaching the web layer.

However, insofar as the nanofibers themselves cannot block every substance, and the nanofibers cannot deliver the range of functionality provided by additional chemical and particulate agents, the particulate materials of the invention are advantageously well secured in the fiber matrix and provide the protection and functionality that cannot be provided by the web alone. Advantageously, as particles are securely held in place within the composite web, settling of particles or loss of patches of particles that would lead to catastrophic failure in some applications is prevented. For example, to be an effective radiation barrier, lead or tungsten particles must be held in place uniformly and without settling or loss of particles that would constitute a breach in the radiation protective barrier formed by the uniform distribution of particles throughout the web.

The techniques used to form the elastomeric nonwoven nanofiber composite webs of the invention are described generally in Chung et al., U.S. Patent Nos. 7,070,640, 6,924,028, 6,955,775, and 7,090,715; and U.S. Patent Publication Nos. 2006/0117730 and 2007/0012007; and pending U.S. Patent Application Nos.

11/398,922, 11/331,555, 11/398,788, and 11/592,402, all of which are incorporated herein by reference. A variety of techniques have been used for the manufacture of small diameter micro- and nanofibers. One method involves passing the material through a fine capillary or opening either as a melted material or in a solution that is subsequently evaporated. Fibers can also be formed by using "spinnerets" typical for the manufacture of synthetic fiber such as nylon. Electrostatic spinning, as described in the above references, is the method of choice for forming the elastomeric nanofiber nonwoven webs of the invention. Such techniques involve the use of a hypodermic needle, nozzle, capillary or movable emitter. These structures provide liquid solutions of the polymer that are then attracted to a collection zone by a high voltage electrostatic field. As the materials are pulled from the emitter and accelerate through the electrostatic zone, the fiber becomes very thin and can be formed in a fiber structure by solvent evaporation.

In the method of this application, particles are incorporated into the elastomeric nanofiber nonwovens generally by feeding particles into a flow of polymer solution using a volumetric screw feeder with an auger. In some embodiments it is advantageous to further use a deflocculator to divide agglomerated particles. The particles are then deposited along with polymer solution and become entangled within the nanofiber network as it forms upon drying of the polymer solution. It will be appreciated that more than one type of particle is easily incorporated into the webs of the invention by providing a particle mix in the volumetric screw feeder; or by providing more than one feeder supplying particles to the flow of polymer solution, hi this way, different particles are easily incorporated into a single web.

While a variety of particles can be incorporated into a single web layer, it can be advantageous to provide more than one elastomeric nanofiber composite web in a multilayer structure. For example, a gradient of particle density can be more easily formed by stacking multiple layers of composite webs on top of each other, wherein each layer has a different particle density. Alternatively, it can be advantageous to provide a barrier against one material in a separate layer from a second barrier. For example, it can be preferable to block electromagnetic radiation in a first layer, then provide a reactive layer for chemical agents that diffuse through the first layer, especially where the reactive layer is adversely affected by electromagnetic radiation. Such protection could be incorporated into a single element by providing two layers in the desired order.

It can also be advantageous to provide one or more additional functional layers to the webs that are not the elastomeric nonwoven nanofiber composite webs of the invention. A functional layer can be a coating or a separately formed layer of material. For example, microporous layers, foam layers, expanded polytetrafluoroethylene layers, heat insulating layers, water repellent layers or coatings, oil repellent layers or coatings, radiation protective layers or coatings, absorptive layers or coatings, printable layers or coatings, antireflective layers or coatings, antiretroreflective layers or coatings, antiviral layers or coatings, antibacterial layers or coatings, antifungal layers or coatings, insect repelling layers or coatings, binder layers or coatings, flame retardant layers or coatings, odor masking layers or coatings, or a combination thereof can be provided on one or both sides of the elastomeric nonwoven nanofiber composite webs of the invention. Such additional layers can add additional functionality to the web when that functionality is not practical to build into such functionality into the web as it is formed. For example, for providing adhesion of the web onto a substrate, it can be desirable not to provide a fiuorochemical coating to the web. But where oil repellency is desirable in the application, fluorochemicals provide the requisite protection. Thus, after forming the elastomeric nonwoven nanofiber composite web and adhering it to a substrate, a fluorochemical coating can be provided to impart oil repellency without affecting adhesion of the web to the substrate. The elastomeric nonwoven nanofiber composite webs of the invention are preferably provided on a substrate. Together, a substrate and at least one elastomeric nonwoven nanofiber composite web disposed on at least one side of the substrate form a barrier element. The substrate can be, in itself, a filtration layer; or it can be a nonfiltration layer as the term "filtration" is commonly understood in the art. For example, the webs of the invention can be formed on top of a nonwoven filter medium such as a dust mask, a fume mask, an HVAC (heat, ventilation, and air conditioning) filter, a HEPA (high efficiency particulate air) filter, a depth filter, a liquid filter, a paper filter, or an absorptive fabric, wherein the webs of the invention add specialized filtration or barrier capabilities. The webs of the invention can be formed or provided on top of a liquid filtration unit, such as a water filtration cartridge material. Such use would provide advantageous specialty filtration capability to target specific hazardous substances from water. For example, infiltration of fluorochemicals into groundwater sources has recently become a problem. Where simple charcoal filters are insufficient, for example, to remove such materials, a specialty particle incorporated into the elastomeric nonwoven nanofiber composite webs of the invention specifically intended to absorb fluorochemicals could be used. The elastomeric nonwoven nanofiber composite webs of the invention can also be provided on top of other materials, such as films, foams, monolithic articles, and the like, to provide protective barrier functionality to any number of articles or materials in applications that are not particularly limited by the examples presented herein.

It should be understood that insofar as the elastomeric nonwoven nanofiber composite webs of the invention can be provided on a substrate to form a barrier element, the webs themselves can comprise any of the embodiments as set forth above, including ranges of particle types, sizes, aspect ratios and functionalities; materials and physical properties of the elastomer; physical properties and chemical characteristics of the nonwoven webs; additives or additional layers that can be used in conjunction with the webs; and the like.

Preferably, the substrates used in conjunction with the barrier elements of the invention are garment fabrics. When joined together, the webs of the invention and standard garment fabrics advantageously comprise fabrics useful in making garments that protect against hazardous materials. Garment applications take advantage of four of the unique aspects of embodiments of the current invention: the lightweight nature of the particle filled webs of the invention, the soft hand of the webs, the high surface area and thus fast reaction or sorption time of hazardous materials afforded by the use of small particles in the web, and the ability of the web to hold the particles securely in place even with the stress, strain, and abrasion expected of garments in use. In addition to garments made to be worn, garment fabrics can also be used to make tents, drapes, bags, and other protective equipment for enclosing or storing people, animals, or other materials or substances, thus protecting them from hazardous substances.

Garment fabrics used in the applications can be, without any particular limitation of fabric type, a nonwoven or a woven or knitted fabric. A nonwoven fabric can be a nonwoven polyester, polyolefin, or another garment fabric that is made from a nonwoven material. A woven or knitted fabric can be cotton fiber, ramie fiber, polyester fiber, nylon fiber, rayon fiber, silk fiber, acetate fiber, wool fiber, hemp fiber, glass fiber, carbon fiber, or blend thereof or a blend with another fiber. As barrier elements, the garment fabrics of the invention are useful in protective garment applications.

Garment fabrics further can comprise agents such as colorants, chemical indicators, radiation indicators, retroreflective elements, reflective elements, UV stabilizing agents, and the like that are particularly useful to garment applications and especially for protective garment applications.

Joining the elastomeric nonwoven nanofiber composite webs of the invention with substrates, including fabric substrates, can be accomplished advantageously in one of two ways. The webs can be preformed and then joined to the substrate, e.g. by a glue, pressure sensitive adhesive, hot melt adhesive, water sensitive adhesive, and the like. The preformed web can also be joined to some substrates by mechanical bonding, such as sewing, spot welding, or other well known bonding methods. However, in many applications it is advantageous to contact the elastomeric nonwoven nanofiber composite webs of the invention onto the substrate directly after the web is formed. Because of the electrospinning methodology used to form the elastomeric nonwoven nanofiber composite webs of the invention, residual solvent that is present in the fibers of the web immediately after the electrospinning process can cause the elastomeric polymers of the nanofiber web to bond to the substrate sufficiently such that no additional operations or materials are needed to affect a good level of adhesion. The electrospinning solvent, being a good solvent for the elastomer, causes the polymer to be relatively soft and swollen, or even partially dissolved or dispersed, prior to complete solvent removal by drying. The polymer can, in such a state, develop adhesion to a web by intermingling with the first surface layers of the substrate. Such adhesion is most likely to develop where the substrate is a fabric. Whether a nonwoven, woven, or knitted, the open, discontinuous structure of fibers in a fabric allows more of a chance for the interlocking of the elastomeric nonwoven nanofiber composite webs of the invention with the fibers during the period when the nanofiber web has residual solvent prior to complete drying .

More than one layer of the elastomeric nonwoven nanofiber composite webs of the invention can be provided on a substrate. In many embodiments, multiple webs are provided contiguously to one another, e.g. multiple layers elastomeric nonwoven nanofiber composite webs on a single side of a substrate. Providing more than one layer provides flexibility in layering particles to provide optimized protection against hazardous materials. Using the same techniques as are used to form a single web, additional web(s) can be deposited directly onto the first web. Thus, a variety of particulates, or a gradient of particulate density, or both are easily realized using the techniques described above to form multiple layers of elastomeric nonwoven nanofiber composite web. The total thickness of the multiple web layers is preferably about 5 to 1000 micrometers.

Additionally, two substrate layers can enclose the one or more layers of elastomeric nonwoven nanofiber web(s) of the invention. Most preferably such constructions are formed in a protective garment application. Such constructions provide greater protection for the web, particularly against abrasion, that is encountered in a garment application. Preferred embodiments are shown in FIGURES 2, 3, and 4 and are generally described in the Summary of the Invention above.

Additional layers or coatings can be incorporated into the barrier elements of the invention. As such, any of the additional layers, functional layers, coatings, impregnated materials, and the like as described above can be incorporated into the web, or further within the particles disposed within the web, or can alternatively be disposed in the substrate itself, or can be within a layer disposed between the web and the substrate.

An advantage of joining the elastomeric nonwoven nanofiber web(s) of the invention with garment fabrics is that the fabrics have an unusually soft hand, good drape, and good permeability compared to other protective fabrics that are generally available. Preferably the fabrics used in such applications are less than 5 millimeters thick, more preferably between about 300 micrometers and 3 millimeters thick. When such garment fabrics are used in the application, good stiffness and permeability are observed. Preferably, using ASTM Dl 388, the stiffness of the garment fabrics of the invention have a stiffness of about 25 mg/cm to 500 mg/cm, more preferably about 25 mg/cm to 200 mg/cm. For example, carbon filled polyurethane nanofiber webs provided on Nomex® substrates is 151 mg/cm in the warp direction. The garment fabrics of the invention also have good permeability and breathability for the comfort of the wearer. The fabrics used in forming barrier elements that are protective garment fabrics typically have a permeability of about 0. lfpm to 5000 fpm. The webs provided on the garment fabrics preferably have a total thickness of about 5 micrometers to 1000 micrometers, more preferably about 50 micrometers to 250 micrometers. Most advantageously, the elastomeric nonwoven nanofiber composite webs of the invention, when provided on fabric substrates, provide surprisingly high durability to the flexing, stress, and strain commonly encountered in garment applications. As such, the current invention represents a major advance in the art. Preferably, the barrier elements of the invention, embodied as garment fabrics, have sufficient adhesion of the particles in the web to result in a weight loss of less than about 10 wt% based on the original weight of the composite web when measured using the Gelbo Flex Test, ASTM F 392 Condition B. More preferably the weight loss is less than about 5 wt% based on the original weight of the composite web, and most preferably the weight loss is less than about 1 wt% based on the original weight of the composite web. Such low levels of weight loss means that the elastomeric nonwoven nanofiber composite webs of the invention have the requisite durability to withstand protective garment applications and provide reliable protection, even with abrasion, flexing, stress, and strain commonly encountered in such applications.

These and other advantages, including the best mode of the invention, are set forth in the Experimental section below.

Experimental Section

EXPERIMENTAL PROTOCOLS

1. Permeability

Permeability relates to the quantity of air (ft³-min^"1, or CFM) that will flow through a square foot of a filter medium at a pressure drop of 0.5 inches of water or the face velocity which induces a 0.5 inches of water restriction. Units can be described as CFM/ft², or feet per minute (fpm). In general, permeability as the term is used is assessed by the Frazier Permeability Test according to ASTM D737 using a Frazier Permeability Tester available from Frazier Precision Instrument Co. Inc., Gaithersburg, Maryland or a TexTest 3300 or TexTest 3310 available from Advanced Testing Instruments Corp (ATI), 243 East Black Stock Rd. Suite 2, Spartanburg, So. Carolina 29301, (864)989-0566, www.aticorporation.com. 2. Fractional Efficiency (DOP) Test - Efficiency, Penetration, and Resistance

Media is mounted in the chuck of a TSI 3160 Automated Filter Tester, available from TSI Incorporated of Shoreview, MN. Dried air is fed with atomized dioctylphthalate (DOP) oil, equivalent, or NaCl particles. The face velocity of the air stream is set by adjusting the flow rate of the air/particle mixture as well as the opening size of the chuck. For example, a flow rate of 32 fpm through a chuck size of 100 cm² will result in a face velocity of 5.3 cm/sec (or 10.5 fpm). In this manner, face velocities ranging from 0.35 fpm to 82 fpm can be achieved.

The DOP / NaCl particles used in the test were 0.020μm, 0.060μm, 0.090μm, 0.300μm, and 0.400μm in diameter. The percent of each particle size trapped by the filter at the designated flow rate was measured. The filtration efficiency is the total percent of each size particle that is trapped by the filter sample. Penetration is calculated based on the formula: Penetration = 1 - Efficiency. Resistance is measured by the Automated Filter Tester, which is equipped with an electronic manometer.

3. Gelbo Flex Test

Gelbo Flex Testing is generally described by ASTM F 392 Condition B. Samples were cut to 8 x 11 inches; thus, two types of samples were cut for each example, one in the machine direction and one in cross-machine direction. The samples were allowed to equilibrate in a glove box for 24 hours, such that weight change due to water loss was stabilized. After weighing the samples inside the glove box, the samples were flexed at ambient room conditions on a Gelbo Flex Durability Tester (Model 5000ES available from Instrument Marketing Services, Inc. of Fairfield, NJ). The flexing action consisted of a twisting motion combined with a horizontal motion, thus, repeatedly twisting and crushing the samples. The cycle frequency was 45 cycles per minute. The samples were flexed using Condition B, or full flex for 20 minutes (900 cycles). Each stroke in full flex mode is 6 inches (155 mm) in length, with a twist of 440°. After flex testing, the samples were returned to the glove box for another 24 hours before weighing. The percent weight loss was calculated from the weight before and after flex testing. The average of machine direction and cross-machine direction was taken for each sample to arrive at the overall percent weight loss. EXAMPLE 1

An elastomeric nonwoven nanofiber composite web of the invention was made using carbon particles and elastomeric polyurethane. The polyurethane was obtained from Noveon Inc. (of Cleveland, OH) as was identified as SP-80A-150. The manufacturer specifications indicated that the polyurethane had an ultimate elongation measured using ASTM D412 test method as minimum 500%, maximum 1500%. Tensile strength at 100% elongation is reported as 468 psi using the same test standard. The polyurethane elastomer was dissolved in ethyl alcohol at 60 ⁰C by vigorous stirring for 5-6 hours until the solids were completely dissolved, followed by cooling to 25°C overnight. The solids content of the solution was 13 % by weight and the viscosity of the resulting solution was around 400 cP as measured using a Brookfield viscometer. The polymer solution was electrospun based on prior teachings described in other Donaldson patents. During the electrospinning, carbon powder (Milled Asbury carbon, mean diameter 13 micrometers, available from Asbury Carbons Company of Asbury, NJ) was constantly weighed and fed at a constant feed rate into the flow of polymer solution using a volumetric screw feeder with an auger. The flow rate was metered to provide about 20 g/m² into the finished composite web. The particles were fed into a deflocculator, which imparted sufficient momentum to the particles enabling them to deposit onto the collector. This was accomplished using compressed air at the deflocculator. In this manner, the particles and fibers were deposited simultaneously creating an intermixed composite. A total of 20 g/m² of carbon powder were incorporated inside the nanofiber composite and the polyurethane fibers weighed about 12 g/m².

The composite was deposited onto a Nomex® blend fabric substrate (available from the DuPont Corporation of Wilmington, DE) and dried. This sample is referred to as EX-I. A view of the top of the composite web EX-I is shown in FIGURE 5. FIGURE 5A shows the web at IOOOX while FIGURE 5B shows the same view at 300X. Visible are nanofibers 2 and fibers of the Nomex® substrate 4. An edge view of the composite web is shown in FIGURE 6. FIGURE 6A shows the web at IOOOX and FIGURE 6B shows the same view at 10OX. Visible in FIGURE 6 A are nanofibers 2 and particles 3. It can be observed that the nanofiber web 2 surrounds and entraps particles 3. Visible in FIGURE 6B are nano fiber web 1 and Nomex® fibrous substrate 4.

The fabric EX-I had an overall basis weight of 242 g/m² and a permeability of 7.84 cfm. EXAMPLE 2

In order to test the composite nanofiber webs of the invention when incorporated into fabrics suitable for protective garment use, a representative example of a nanofiber web using polyurethane elastomer and carbon particles supplied on Nomex® substrate was prepared as described in Example 1. As controls, fabric constructions mimicking those currently used commercially in protective garment applications were fabricated.

CONTROL-I is Lifetex® CD-2010-1 fabric, a multi-layer fabric laminate consisting of a woven Nomex® outer layer, an adsorptive layer utilizing spherical activated carbon and a Nomex®/PBI® blend knit inner fabric; it is available from Gentex Corporation of Carbondale, PA. Lifetex® CD-2010-1 is sold as a protective garment fabric. It has a basis weight of 531.73 g/m².

CONTROL-2 is Lifetex® CD-2560-4 fabric, which includes an outer layer of 50% cotton/50% nylon woven ripstop fabric; it is available from Gentex Corporation of Carbondale, PA. Lifetex® CD-2560-4 is sold as a protective garment fabric. It has a basis weight of 708.85 g/m².

EX-2 was made by electrospinning elastomeric polyurethane SP-80A-150, from Noveon Inc. of Cleveland, OH at a basis weight of 25 g/m² along with carbon powder (milled Asbury carbon, 13 μm average diameter, from Asbury Carbons Co. of Asbury, NJ) for a loading of 40 g/m² using the techniques described in Example 1. The electrospun web was provided on Nomex® substrate (from DuPont Corp. of Wilmington, DE), which has a basis weight of 210 g/m². A comfort knit layer was provided on the top of the nanofiber layer for the purpose of stiffness testing. The comfort layer used was SD 1514, obtained from SMM Industries of Spring City, TN. The finished construction had a basis weight of 432.38 g/m². CONTROL-I, CONTROL-2, and EX-32 were tested for softness using two techniques. The SHIRLEY Cantilever ASTM D 1388 Standard Test method for stiffness of fabric was performed on the commercially available Shirley Fabric Stiffness Tester (available from SDL Atlas Ltd., Stockport, England). The instrument allows a rectangular strip of fabric to bend under its own weight to a fixed angle when projected as a cantilever. The fabric sample in the instrument represents a cantilever beam that is uniformly loaded by its own weight and bends downward until it reaches 45 degrees from the horizontal plane. The longer the projected length, the stiffer the fabric is. The fabric sample is placed below a metal ruler and slowly moved forward. The movement of the fabric continues on the tapered surface until the tip of the specimen viewed in the mirror cuts both the index lines. Then bending length is read from the scale mark opposite to the zero line engraved on the platform. From the length (I) and the angle (θ) bending length (Q is calculated using the formula

C = If₁(B) aαd/i(0) = [(cos QIl)I (8 tan θ)] 1/3

Flexural rigidity (stiffness) of the fabric can be calculated from bending length (C) and weight using the formula

G = 3.39 w C³ mg/cm

where (w) is the cloth weight in ounces per square yard. Results of Shirley Stiffness testing for CONTROL-I, CONTROL-2 and EX-2 are shown in Table 1.

Table 1. Results of Shirley Fabric Stiffness Testing.

The three samples were also tested using the Tinius Olsen Cantilever Bending Method, ASTM D 747 and Fed. Std. 191-5203. In this test, material is bent to a 60 degree deflection using a machine with a specimen vise, pendulum weighing system (moment weight), angular deflection scale and a fixed load scale which measures the deflection of the pendulum system. Thus the bending moment (in. Ib.) is the load scale x the moment weight divided by 100. The results of testing are shown in Table 2.

Table 2. Results of Tinius Olsen Cantilever Bending test.

As can be seen from both types of stiffness testing, the elastomeric nanofiber composite web of the invention has more drape and less stiffness than commercial type constructions used for protective garments. The sample also had exceptional softness to the touch.

EXAMPLE 3 m the same manner as described in Example 1, various nanofiber webs were spun using the nanofiber materials, particles, particle loadings, and substrates as indicated in Table 3. The specific materials generated are shown in Table 4. Table 3. Materials and amounts used in various composite webs deposited on fabric.

Table 4. Constructions generated using the materials designated in Table 3.

The above samples were subjected to Gelbo Flex Testing. The results of the testing are shown in Table 5. Also shown in Table 5 is the permeability for each sample, measured prior to Gelbo Flex testing. In some cases, the permeability was also measured after testing.

Table 5. Permeability, results of Gelbo Flex testing for samples EX-I and EX-3 to EX-25.

Micrographs of EX-I taken after flex testing are shown in FIGURES 7 and 8. FIGURES 7 A and 7B are micrographs of the surface of the nanofiber web after flex testing, taken at IOOOX and 300X, respectively. The micrographs are analogous to FIGURES 5A and 5B and were taken at the same magnification in order to provide a means of comparison, hi FIGURE 7 A, areas of damages 10 are seen on the surface of the nanofiber web. It can be seen in FIGURE 7B, however, that the areas of damage 10 are minor; further, these micrographs show only the surface layer of fibers.

FIGURES 8A and 8B show the EX-I web at 500X and 200X, respectively.

Visible in FIGURE 8A are nanofibers 2 and particles 3 as well as fibers of the Nomex® fibrous substrate 4. It can be observed that the nanofiber web 2 still surrounds and entraps particles 3, despite the minor damage on the surface of the web that was observed in FIGURE 7. Visible in FIGURE 8B are nanofiber web 1 and Nomex® fibrous substrate 4. Thus, while the surface of the web can show signs of some damage after flex testing, the particles remain firmly entrained within the network. The surface damage observed does not significantly impact the performance of the web in retaining the particulate.

FIGURES 9A-G show photographs of fabric constructions EX-I and EX- 15 to -20, respectively, after Gelbo Flex testing. The photos were taken of cross- machine direction tested samples. As can be seen, particle type C, or alumina, resulted in better appearance overall after Gelbo Flex testing (Samples EX- 18 to EX-20, FIGURE 9E-G), even though samples EX-I and -15 to -17 showed less actual weight loss in the test. Also of note is that sample EX-20, shown in FIGURE 9G, does undergo some visible damage; this appears to be due to the high particle loading (40 g/cm²).

EXAMPLE 4

Fractional efficiency was measured for samples EX-I, -8, -10, and -15 to -20 using the Efficiency (DOP) test. The results of testing are shown in Table 6.

Table 6. Fractional efficiency test results of EX- 1 , -8, - 10, and - 15 to -20

SAMPLE EFFICIENCY TEST RESULTS

EX-8 Face velocity cm/s 5.307

Diameter Efficiency Penetration Resistance μm % % HImH₂O

0.020 99.988 0.022 31.122

0.060 99.483 0.527 31.139

0.090 98.892 1.118 31.142

0.300 99.497 0.513 31.157

0.400 W⁰⁶ 0.304 31.144 EX-IO Face velocity cm/s 5.334

Diameter Efficiency Penetration Resistance μm % % mmEbO

0.020 99.998 0.002 32.478

0.060 99.870 0.130 32.532

0.090 99.668 0.332 32.543

0.300 99.826 0.174 32.545

0.400 99.936 0.064 32.559

EX-I Face velocity cm/s 5.354

Diameter Efficiency Penetration Resistance μm % % mmEbO

0.020 99.922 0.078 16.299

0.060 97.879 2.121 16.245

0.090 96.196 3.804 16.227

0.300 97.923 2.077 16.218

0.400 98.997 1.003 16.213

EX-15 Face velocity cm/s 5.323

Diameter Efficiency Penetration Resistance μm % % mmH2O

0.020 99.969 0.031 71.653

0.060 99.837 0.163 71.693

0.090 99.690 0.310 71.733

0.300 99.911 0.089 71.752

0.400 99.789 0.211 71.769

EX-16 Face velocity cm/s 5.348

Diameter Efficiency Penetration Resistance μm % % mmH2O

0.020 99.960 0.040 21.058

0.060 99.177 0.823 20.658

0.090 98.253 1.747 20.529

0.300 98.923 1.077 20.418

0.400 99.380 0.620 20.330

EX-17 Face velocity cm/s 5.341

Diameter Efficiency Penetration Resistance μm % % mmH2O

0.020 99.761 0.239 103.227

0.060 99.932 0.068 103.276

0.090 9Φ1875 0.125 103.303 0.300 99.672 0.328 103.355

0.400 96.335 3.665 103.490

EX-18 Face velocity cm/s 5.323

Diameter Efficiency Penetration Resistance μm % % mmH2O

0.020 99.969 0.031 88.935

0.060 99.948 0.052 87.337

0.090 99.918 0.082 87.124

0.300 99.482 0.518 87.104

0.400 98.195 1.805 87.064

EX-19 Face velocity cm/s 5.335

Diameter Efficiency Penetration Resistance μm % % mmH2O

0.020 98.909 1.091 54.741

0.060 99.866 0.134 54.855

0.090 99.759 0.241 54.930

0.300 98.032 1.968 54.934

0.400 91.271 8.729 54.952

EX-20 Face velocity cm/s 5.337

Diameter Efficiency Penetration Resistance μm % % mmH2O

0.020 98.788 1.212 89.511

0.060 99.867 0.133 89.775

0.090 99.764 0.236 89.894

0.300 98.158 1.842 90.010

0.400 91.740 8.260 90.077

It can be seen in Table 6 that the smallest and largest particle sizes are the most efficiently filtered out, in general. EX-10 and EX- 15 have the most efficiency overall, trapping over 99.5% of all particle sizes.

EXAMPLE 5

In order to test the ability of the elastomeric nanofiber nonwoven to seal up around damaged areas, a sewing machine was used to sew a seam into various substrates, after which micrographs were taken to examine the damage around the punctured areas where the thread protruded into the protective nanofiber. EX-I was compared in this application to a control sample, CONTROL-3.

CONTROL-3 was generated using the following technique. Nylon cotton camouflage woven shell fabric having a basis weight of 6 oz/yd² (222 g/m²; available from the H.L. Landau Company of Bala-Cynwyd, PA) was used as a substrate. The substrate was adhered to a PTFE membrane having a pore size of about 2 to 3 micrometers (available from Donaldson Company, Inc. of Minneapolis, MN). The PTFE membrane is a commercially available material used for protective garment applications. The camouflage woven shell fabric was adhered to the PTFE membrane with a discontinuous dot layer of H.B. Fuller S 12/4 hot melt polyurethane adhesive. Samples for the multilayer shell/PTFE membrane fabric testing were obtained from across the width of a 59.5 inch wide roll of multilayer fabric.

A standard sewing machine was used to make standard straight stitches using a standard polyester thread. The fabric side (camouflage shell side in CONTROL-3 and Nomex® side in EX-I) was the puncture side, that is, the side through which the needle initially pierced. Micrographs of the protective layer side of the fabrics were taken and are shown in FIGURE 10.

FIGURE 1OA and 1OB show EX-I and CONTROL-3 at 50X, respectively. It can be seen that the CONTROL-3 sample suffered a greater degree of damage than EX-I . Similarly, in FIGURE 1OC and 10D, which show the same samples at 10OX, it can be seen that the elastomeric web provides a better seal around the thread with less damage to the web than the PTFE web. Similarly, in FIGURE 1OE and 1OF, which show the same samples at 200X, the damage to the elastomeric web is minimal compared to the prior art web CONTROL-3. Minimal damage to the nanofiber web means that particles at or near the site of the needle piercing are better held in place than would be the case in a brittle, nonelastomeric web. This in turn means that the webs of the invention are better suited than webs of the prior art to hold active particles of small particle size in place even where sewing takes place. This in turn means that extraordinary measures such as use of a protective seam tape or other barrier "patch" is less likely to be required in protective applications such as hazardous material barrier garments and articles. Embodiment Section

The invention can have several embodiments. A list comprising suitable embodiments is provided below:

Embodiment 1 may be an active layer, comprising: at least one composite web, the at least one composite web comprising, at least one substantially continuous elastomeric nanofiber with a diameter of 2 micrometers or less, and at least one type of active particles with sizes of 500 micrometers or less;

Embodiment 2 may be the active layer of embodiment 1 wherein the at least one type of active particles is substantially intermixed with the at least one substantially continuous elastomeric nanofiber;

Embodiment 3 may be the active layer of embodiment 1 wherein the at least one composite web has a permeability of about 0.1 to 100 fpm inclusive;

Embodiment 4 may be the active layer of embodiment 1 wherein the fiber diameter is 1 micrometer or less;

Embodiment 5 may be the active layer of embodiment 1 wherein the at least one type of active particles sizes are 300 micrometers or less; Embodiment 6 may be the active layer of embodiment 1 wherein the at least one type of active particles sizes are 200 micrometers or less;

Embodiment 7 may be the active layer of embodiment 1 wherein the at least one type of active particles sizes are 100 micrometers or less;

Embodiment 8 may be the active layer of embodiment 1 wherein the surface areas of the at least one type of active particles are about 100 m /g to 2000 m /g inclusive;

Embodiment 9 may be the active layer of embodiment 1 wherein the surface areas of the at least one type of active particles are about 1200 m /g to 2000 m /g inclusive; Embodiment 10 may be the active layer of embodiment 1 wherein the surface areas of the at least one type of active particles are greater than about 500 m²/g; Embodiment 11 may be the active layer of embodiment 1 wherein the nanofiber is present in the at least one composite web at about 5 wt% to 95 wt% inclusive based on the total weight of the at least one composite web;

Embodiment 12 may be the active layer of embodiment 1 wherein the nanofiber is present in the at least one composite web at about 20 wt% to 50 wt% inclusive based on the total weight of the at least one composite web;

Embodiment 13 may be the active layer of embodiment 1 wherein the at least one type of active particles are present in the at least one composite web at about 5 wt% to 95 wt% inclusive based on the total weight of the at least one composite web;

Embodiment 14 may be the active layer of embodiment 1 wherein the at least one type of active particles are present in the at least one composite web at about 50 wt% to 80 wt% inclusive based on the total weight of the at least one composite web; Embodiment 15 may be the active layer of embodiment 1 wherein the at least one composite web thickness is about 5 to 1000 micrometers inclusive;

Embodiment 16 may be the active layer of embodiment 1 wherein the at least one composite web thickness is about 50 to about 250 micrometers inclusive;

Embodiment 17 maybe the active layer of embodiment 1 wherein the at least one composite web has a basis weight of about 5 to 500 g/m² inclusive;

Embodiment 18 may be the active layer of embodiment 1 wherein the at least one composite web has a basis weight of about 10 to 100 g/m² inclusive;

Embodiment 19 may be the active layer of embodiment 1 wherein the at least one substantially continuous elastomeric nanofiber has an elongation at break of about 200 to 2000% inclusive and tensile strength at 100% elongation of about 10 to 1000 psi inclusive when measured according to ASTM D412;

Embodiment 20 may be the active layer of embodiment 1 wherein the at least one substantially continuous elastomeric nanofiber has an elongation at break of about 500 to 1500% inclusive when measured according to ASTM D412; Embodiment 21 may be the active layer of embodiment 1 wherein the at least one substantially continuous elastomeric nanofiber has a tensile strength at 100% elongation of about 300 to 700 psi inclusive when measured according to ASTM D412; Embodiment 22 may be the active layer of embodiment 1 wherein there is sufficient adhesion of the at least one type of active particles in the at least one composite web to provide less than 10 wt% loss, based on the weight of the at least one composite web, after mounting the at least one composite web on a fabric backing and subjecting the at least one composite web and fabric to ASTM F392 condition B

Embodiment 23 may be the active layer of embodiment 1 wherein the at least one substantially continuous elastomeric nanofiber is a natural rubber, an elastin, a resilin, a polyisoprene, a polyisobutylene, a polybutadiene, an ethylene- vinyl acetate polymer, a halobutyl rubber, a styrene-butadiene polymer, a hydrated butadiene- styrene copolymer, a polychloroprene, an ethylene-propylene copolymer, an ethylene-propylene-diene copolymer, an epichlorohydrin rubber, a polyacrylic rubber, a silicone elastomer, a silicone rubber, a fluorosilicone rubber, a fluoroelastomer, a tetrafluoroethylene-propylene rubber, a chlorosulfonated polyethylene, a polyester elastomer, a polyether-amide block elastomer, a silicone elastomer, a polysulfide rubber, a copolymer thereof, a mixture thereof, or a mixture thereof with another polymer;

Embodiment 24 may be the active layer of embodiment 1 wherein the at least one substantially continuous elastomeric nanofiber comprises a polyurethane elastomer;

Embodiment 25 may be the active layer of embodiment 1 wherein the at least one type of active particles comprise a chemically absorbent particle type, a chemically adsorbent particle type, a chemically reactive particle type, a biologically reactive particle type, or a mixture of absorbent and reactive particle types; Embodiment 26 may be the active layer of embodiment 1 wherein the at least one type of active particles comprise an activated carbon, an alumina, an activated alumina, an alumina-carbon composite, a titanium dioxide, a lead, a tungsten, or an agglomerated silica;

Embodiment 27 may be the active layer of embodiment 1 wherein the at least one type of active particles comprise at least one member of a group comprising metal organic frameworks, covalent organic framework, and iso-reticular metal- organic framework; Embodiment 28 may be the active layer of embodiment 27 wherein the at least one type of active particles are spacers;

Embodiment 29 may be the active layer of embodiment 1 wherein the at least one type of active particles are a bioactive particles; Embodiment 30 may be the active layer of embodiment 29 wherein the bioactive particles comprise a cell, a microorganism, an enzyme, a bioactive molecule, or a mixture thereof;

Embodiment 31 may be the active layer of embodiment 29 wherein the bioactive particles are not biological; Embodiment 32 may be the active layer of embodiment 29 wherein the bioactive particles are cellulytic or cytotoxic;

Embodiment 33 maybe the active layer of embodiment 1 wherein the at least one type of active particles have an aspect ratio of about 1:1 to 1:100 inclusive;

Embodiment 34 may be the active layer of embodiment 1 wherein the at least one type of active particles have an aspect ratio of about 1 : 1 to 1 : 10 inclusive;

Embodiment 35 maybe the active layer of embodiment 1 wherein the at least one type of active particles are further treated with an agent to modify the adsorption characteristics of the at least one type of active particles;

Embodiment 36 maybe the active layer of embodiment 1 further comprising at least two types of active particles in the at least one composite web;

Embodiment 37 maybe the active layer of embodiment 36 wherein the first type of the at least two types of active particles is a spacer type particle;

Embodiment 38 may be the active layer of embodiment 1 wherein the at least one composite web is capable of aerosol filtration efficiency of at least about 30 to 99.9999% inclusive measured at 0.3 micrometer dioctylphthalate particle size and 10.5 fpm face velocity;

Embodiment 39 may be the active layer of embodiment 1 wherein the at least one composite web provides a barrier function to one or more hazardous materials;

Embodiment 40 may be the active layer of embodiment 39 wherein the one or more hazardous materials are toxic industrial chemicals, household chemicals, institutional chemicals, sanitation chemicals, chemical warfare agents, or biological warfare agents; Embodiment 41 may be the active layer of embodiment 39 wherein the substantially continuous elastomeric nonwoven nanofiber provides the barrier function;

Embodiment 42 may be the active layer of embodiment 39 wherein the at least one type of active particles provide the barrier function;

Embodiment 43 may be the active layer of embodiment 42 wherein the at least one type of active particles absorb the one or more hazardous material;

Embodiment 44 may be the active layer of embodiment 43 wherein the at least one type of active particles comprise a synthetic zeolite, a natural zeolite, a layered mineral, an activated carbon powder, a carbon granule, a porous bead, or a shaped monolith;

Embodiment 45 may be the active layer of embodiment 43 wherein the at least one type of active particles react with the one or more hazardous material;

Embodiment 46 may be the active layer of embodiment 45 wherein the at least one type of active particles comprise a layered mineral partly filled with a sodium chlorite, an agglomeration of alumina and activated carbon, or an agglomerated alumina;

Embodiment 47 may be the active layer of embodiment 42 wherein the at least one type of active particles react with the one or more hazardous material; Embodiment 48 may be the active layer of embodiment 47 wherein the at least one type of active particles adsorb the one or more hazardous material;

Embodiment 49 may be the active layer of embodiment 48 wherein the at least one type of active particles comprise at least one member of a group comprising metal organic frameworks, covalent organic framework, and iso- reticular metal-organic framework;

Embodiment 50 may be the active layer of embodiment 48 wherein the at least one type of active particles comprise an activated carbon and a reactively decomposing material;

Embodiment 51 may be the active layer of embodiment 42 wherein the at least one type of active particles comprise a polyoxometalate, an alumina, a shaped monolith, or a calcium oxide;

Embodiment 52 may be the active layer of embodiment 1 further comprising an agent, the agent comprising a flame retardant, a water repellent, an oil repellent, an antimicrobial, an antiviral, a binder, an antifungal, an odor masking, or an insect repelling agent;

Embodiment 53 may be the active layer of embodiment 52 wherein the agent resides substantially within the at least one type of active particles; Embodiment 54 may be the active layer of embodiment 1 further comprising at least two composite webs;

Embodiment 55 maybe the active layer of embodiment 1 further comprising one or more functional layers;

Embodiment 56 may be the active layer of embodiment 55 wherein the one or more functional layers comprise a microporous layer, a foam layer, an expanded polytetrafluoroethylene layer, a heat insulating layer, a water repellent layer, a water repellent coating, an oil repellent layer, an oil repellent coating, a radiation protective layer, a radiation protective coating, an absorptive layer, an absorbent coating, a printable layer, a printable coating, an antireflective layer, an antireflective coating, an antiretroreflective layer, an antireflective coating, an antiviral layer, an antiviral coating, an antibacterial layer, an antibacterial coating, an antifungal layer, an antifungal coating, an insect repelling layer, an insect repellent coating, a binder layer, a binder coating, a flame retardant layer, a flame retardant coating, an odor masking layer, an odor masking coating, or a combination thereof; Embodiment 57 may be a barrier element comprising a substrate; at least one composite web layer comprising at least one substantially continuous elastomeric nano fiber with a diameter of 2 micrometers or less, the at least one composite web layer deposited on at least one side of the substrate, and at least one type of active particles with sizes of 500 micrometers or less, the at least one type of active particles substantially intermixed with the at least one substantially continuous elastomeric nanofiber;

Embodiment 58 may be the barrier element of embodiment 57 wherein the substrate is a garment fabric; Embodiment 59 may be the barrier element of embodiment 58 wherein the garment fabric is an inner layer;

Embodiment 60 may be the barrier element of embodiment 58 wherein the garment fabric comprises a nonwoven fabric; Embodiment 61 may be the barrier element of embodiment 58 wherein the garment fabric comprises a dust mask, a fume mask, an HVAC filter, a HEPA filter, a depth filter, a liquid filter, a paper filter, or an absorptive fabric;

Embodiment 62 may be the barrier element of embodiment 58 wherein the garment fabric comprises a woven fabric or a knitted fabric;

Embodiment 63 may be the barrier element of embodiment 62 wherein the garment fabric comprises cotton fiber, ramie fiber, polyester fiber, nylon fiber, rayon fiber, silk fiber, acetate fiber, wool fiber, hemp fiber, glass fiber, carbon fiber, a blend thereof, or a blend with another garment fiber; Embodiment 64 may be the barrier element of embodiment 58 wherein the garment fabric further comprises a flame retarding agent, a water repellent agent, an oil repellent agent, an antimicrobial agent, an antiviral agent, an antifungal agent, a UV stabilizing agent, or a chemical indicator, a radiation indicator, a colorant, a reflective element, or a retroreflective element; Embodiment 65 may be the barrier element of embodiment 58 wherein the garment fabric is suitable for protective garment applications;

Embodiment 66 may be the barrier element of embodiment 58 wherein the garment fabric has a stiffness of about 25 mg/cm to 500 mg/cm inclusive as determined using ASTM- D 1388; Embodiment 61 may be the barrier element of embodiment 58 wherein the garment fabric has a stiffness of about 25 mg/cm to 200 mg/cm inclusive as determined using ASTM- D 1388;

Embodiment 68 maybe the barrier element of embodiment 58 wherein the garment fabric has a permeability of about 0.1 fpm to 5000 fpm inclusive; Embodiment 69 may be the barrier element of embodiment 58 wherein the garment fabric thickness is less than about 5 millimeters inclusive;

Embodiment 70 may be the barrier element of embodiment 58 wherein the garment fabric thickness is about 300 micrometers to about 3 millimeters inclusive;

Embodiment 71 may be the barrier element of embodiment 57 wherein the there is sufficient adhesion of the at least one type of active particles in the at least one composite web layer to provide weight loss of the at least one type of active particles of less than about 10 wt% based on the weight of the at least one composite web layer as measured by ASTM F392 condition B; Embodiment 72 may be the barrier element of embodiment 57 wherein the there is sufficient adhesion of the at least one type of active particles in the at least one composite web layer to provide weight loss of the of less than about 5 wt% based on the weight of the at least one composite web layer as measured by ASTM F392 condition B;

Embodiment 73 may be the barrier element of embodiment 57 wherein the there is sufficient adhesion of the at least one type of active particles in the at least one composite web layer to provide weight loss of the at least one type of active particles of less than about 1 wt% based on the weight of the at least one composite web layer as measured by ASTM F392 condition B;

Embodiment 74 may be the barrier element of embodiment 57 further comprising at least two composite web layers;

Embodiment 75 may be the barrier element of embodiment 74 wherein the at least two composite web layers are disposed contiguously to one another; Embodiment 76 may be the barrier element of embodiment 57 wherein the total thickness of the at least one composite web layer is about 5 to 1000 micrometers inclusive;

Embodiment 77 may be the barrier element of embodiment 57 wherein each of the at least one composite web layer comprises at least two types of active particles;

Embodiment 78 may be the barrier element of embodiment 57 further comprising one or more functional layers;

Embodiment 79 may be the barrier element of embodiment 78 wherein the one or more functional layers comprise a microporous layer, a foam layer, an expanded polytetrafluoroethylene layer, a heat insulating layer, a water repellent layer, a water repellent coating, an oil repellent layer, an oil repellent coating, a radiation protective layer, a radiation protective coating, an absorptive layer, an absorbent coating, a printable layer, a printable coating, an antireflective layer, an antireflective coating, an antiretrorefiective layer, an antireflective coating, an antiviral layer, an antiviral coating, an antibacterial layer, an antibacterial coating, an antifungal layer, an antifungal coating, an insect repelling layer, an insect repellent coating, a binder layer, a binder coating, a flame retardant layer, a flame retardant coating, an odor masking layer, an odor masking coating, or a combination thereof Embodiment 80 may be the barrier element of embodiment 78 wherein the one or more functional layers are disposed contiguously with the at least one composite web layer;

Embodiment 81 maybe the barrier element of embodiment 57 further comprising an agent, the agent comprising a flame retardant agent, a water repellent agent, an oil repellent agent, an antimicrobial agent, an antiviral agent, an antifungal agent, an odor masking agent, a binding agent, a radiation protective agent, an absorptive agent, or an insect repelling agent;

Embodiment 82 may be the barrier element of embodiment 81 wherein the agent resides substantially within the at least one type of active particles;

Embodiment 83 may be the barrier element of embodiment 57 wherein the at least one composite web layer thickness is about 50 to about 250 micrometers inclusive;

Embodiment 84 may be the barrier element of embodiment 57 wherein the at least one substantially continuous nanofiber elastomer comprises a polyurethane elastomer;

Embodiment 85 maybe the barrier element of embodiment 57 wherein the at least one type of active particles comprise a chemically absorbent particle type, a chemically adsorbent particle type, a chemically reactive particle type, a biologically reactive particle type, a mixture of absorbent and reactive particle types, or a mixture of adsorbent and reactive particle types;

Embodiment 86 may be the barrier element of embodiment 57 wherein the at least one type of active particles comprise an activated carbon, an activated alumina, an alumina-carbon composite, a titanium dioxide, a lead, a tungsten, or an agglomerated silica;

Embodiment 87 may be the barrier element of embodiment 57 wherein the at least one type of active particles comprise at least one member of a group comprising metal organic frameworks, covalent organic framework, and iso- reticular metal-organic framework; Embodiment 88 may be the barrier element of embodiment 88 wherein the at least one type of active particles are spacers;

Embodiment 89 may be the barrier element of embodiment 57 wherein the at least one type of active particles are a bioactive particles; Embodiment 90 may be the barrier element of embodiment 90 wherein the bioactive particles comprises a cell, a microorganism, an enzyme, a bioactive molecule, or a mixture thereof;

Embodiment 91 may be the barrier element of embodiment 90 wherein the bioactive particle is not biological;

Embodiment 92 may be the barrier element of embodiment 90 wherein the bioactive particle is cytotoxic or cellulytic;

Embodiment 93 maybe the barrier element of embodiment 57 further comprising at least two types of active particles; Embodiment 94 may be the barrier element of embodiment 57 wherein the barrier element is capable of an aerosol filtration efficiency of at least about 30 to 99.9999% inclusive measured at 0.3 micrometer dioctylphthalate particle size and 10.5 fpm face velocity;

Embodiment 95 may be the barrier element of embodiment 57 wherein the barrier element provides a barrier function to one or more hazardous materials;

Embodiment 96 may be the barrier element of embodiment 96 wherein the one or more hazardous materials are toxic industrial chemicals, household chemicals, institutional chemicals, sanitation chemicals, chemical warfare agents, or biological warfare agents; Embodiment 97 may be the barrier element of embodiment 96 wherein the at least one substantially continuous elastomeric nonwoven nanofiber provides the barrier function;

Embodiment 98 may be the barrier element of embodiment 57 wherein the at least one type of active particles provide a barrier function; Embodiment 99 may be the barrier element of embodiment 99 wherein the at least one type of active particles absorb the one or more hazardous material;

Embodiment 100 may be the barrier element of embodiment 99 wherein the at least one type of active particles react with the one or more hazardous material;

Embodiment 101 may be the barrier element of embodiment 101 wherein the at least one type of active particles adsorb the one or more hazardous material;

Embodiment 102 maybe the barrier element of embodiment 102 wherein the at least one type of active particles comprise at least one member of a group comprising metal organic frameworks, covalent organic framework, and iso- reticular metal-organic framework;

Embodiment 103 maybe the barrier element of embodiment 103 wherein the at least one type of active particles are spacers; Embodiment 104 may be the barrier element of embodiment 100 wherein the at least one type of active particles react with the one or more hazardous material; and

Embodiment 105 may be the barrier element of embodiment 105 wherein the at least one type of active particles comprise an activated carbon and a reactively decomposing material.

This list is not restrictive. It is appreciated that other suitable embodiments may be utilized without departing from the scope and intent of the disclosure.

The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.

Claims

ClaimsWE CLAM:

1. An active layer, comprising: at least one composite web, the at least one composite web comprising, at least one substantially continuous elastomeric nanofiber with a diameter of 2 micrometers or less; and at least one type of active particles with sizes of 500 micrometers or less.

2. A barrier element comprising a substrate; at least one composite web layer comprising at least one substantially continuous elastomeric nanofiber with a diameter of 2 micrometers or less, the at least one composite web layer deposited on at least one side of the substrate; and at least one type of active particles with sizes of 500 micrometers or less, the at least one type of active particles substantially intermixed with the at least one substantially continuous elastomeric nanofiber.