US 20050170221 A1
A puncture, pierce, and cut resistant fabric comprised of a plurality of sheets of plates arranged in a repeating pattern. A material interconnects the plates. The fabric is twistable, bendable, and flexible. It is constructed of substances that will withstand cutting, puncture, and piercing forces encountered in medical or other environments.
1. A fabric assembly comprising:
a flexible substrate having a top surface; and
a plurality of continuous, non-overlapping and approximately planar and identical metal plates having substantially uniform thickness of approximately 2 to 5 mils, the plurality of metal plates each having a bottom surface affixed to the top surface of the flexible substrate and arrayed in a pattern such that a plurality of gaps are defined between adjacent affixed plates, wherein the gaps are approximately uniform in width, and wherein the gap width is approximately 2 to 5 mils.
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39. A fabric assembly comprising:
a flexible substrate having a top surface; and
a plurality of non-overlapping polygonal plates affixed to the top surface of the substrate, wherein the plates comprise a thermo-set composite polymer and wherein the plates have a substantially uniform thickness of approximately 5 to 20 mils, the plurality of plates arrayed in a pattern such that a plurality of gaps are defined between adjacent affixed plates, wherein the gaps are approximately uniform in width, and wherein the gap width is approximately 5 to 20 mils.
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a second flexible substrate having a second plurality of continuous, non-overlapping plates affixed to a top surface of the second flexible substrate; and
a third flexible substrate having a third plurality of continuous, non-overlapping plates affixed to a top surface of the third flexible substrate, wherein the first-mentioned, second, and third flexible substrates are arranged in a stack, and wherein each of the second and third pluralities of plates are arrayed in a pattern such that approximately linear gaps are defined between adjacent affixed plates.
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The present application is a continuation of and claims priority of U.S. patent application Ser. No. 09/610,748, filed Jul. 6, 2000, the content of which is hereby incorporated by reference in its entirety.
The fabric of this invention is primarily useful to afford excellent defense and protection against penetration forces including cutting, shearing, and slashing forces, even by jagged or serrated instruments applied at excessive force and impacts of extended duration. The inventive fabric also provides an excellent level of penetration resistance to sharp puncturing and piercing forces.
The fabric is comprised of layers, in which at least one of the layers has an array of plates. The plates in an array maintain a spaced relationship with each other by means of a material substrate.
The penetration resistant inventive fabric is suitable for fabrication of garments and protective coverings that are worn to resist cutting, shearing, slashing, puncturing, and other penetrating forces. Garments of this fabric include protective apparel, such as gloves, worn in medical, industrial, abrasive, outdoor, and other environments in which penetrating forces are experienced. Examples of penetration forces resisted by the inventive fabric include cutting by blades or saws, including high-speed rotating blades; shearing by scissors or blades; slashing by knives or sharp-edged, abrasive, or serrated objects; and puncturing or piercing by needles or pins.
Numerous attempts have been made to fabricate penetration resistant fabrics with supple, flexible, bendable, twistable, and tactile characteristics. The cut, shear, slash, puncture, and pierce resistant fabric of this invention accomplishes each of these necessary goals. A further advantage of this invention is that it is readily adaptable for use in conjunction with conventional liquid barriers. An additional advantage of this fabric is that it can be constructed using breathable materials to increase wearer comfort, especially during extended periods of use of protective garments made from the inventive fabric.
An especially effective and highly desirable use for this fabric is for protective gloves, aprons, sleeves, footwear, and other garments. Gloves and garments constructed from the fabric of this invention find use in the medical industry where a high level of tactility is required such as gloves for surgical use. The fabric is also useful for sports people and outdoors people engaged in fishing, hunting, and similar activities. Gloves and garments constructed from the fabric of this invention are useful for protecting the wearer from industrial injuries in factories, on construction sites, in solid waste handling facilities, and in other such hazardous environments.
Due to the rising numbers of wounds from knives and other cutting instruments, there is a strong demand for an effective and user-comfortable protective barrier against these body cutting, shearing, slashing, and piercing weapons. Furthermore, public safety personnel (police officers, fire fighters, paramedics, and first responders) who must physically examine a person, a corpse, clothing, or other objects are in great need of protection from sharp objects, which might possibly be contaminated with a life-threatening infectious organism.
Currently available, breathable protective gloves and body armor are generally of a knit or woven construction. Knit or woven construction provides minimal protection against blade cutting, such as knives. It provides even less protection against abrasive or serrated instruments, such as serrated knives, saw blades, jagged metal, or glass. And, it provides virtually no protection against puncture or piercing.
Non-porous and, therefore, non-breathing synthetics constitute the construction of some currently available protective gloves and body armor. Such synthetics include aramids, such as Kevlar®, and polyethylenes, such as Spectra®. Such synthetics may be effective at stopping body-piercing projectiles, such as bullets, but are ineffective at resisting wounds from knives or other sharp or jagged edged objects. Such synthetics are also uncomfortable, since they prevent evaporation of perspiration from the wearer's skin.
Another advantage of the fabric of this invention is that it (i) provides dependable resistance to penetration, while (ii) allowing ease of movement due to its characteristic flexibility, bendability, and twistability, and (iii) optionally can be fabricated of breathable materials to allow evaporation of perspiration. Alternately, the fabric can be fabricated of liquid barrier materials.
The fabric exhibits properties of flexibility, bendability, twistability, and, optional stretchability, by an arrangement of layers, in which at least one layer is an array of plates connected to form a generally two-dimensional sheet.
The plates are of a tough, hard, and strong substance that is not friable or brittle. The substance type and the thickness of the individual plates will differ according to its application, such as whether the fabric must be cut or penetration resistant and the level and type of force to be resisted.
The fabric is comprised of layers, in which at least one of the layers has an array of plates. The plates in an array maintain a spaced relationship with each other by means of a material substrate.
The material substrate may be a connecting material to which the plates are affixed or attached and it may become an integral part of each of the plates in the array. The connecting material interconnects the plates so that the plates are spaced apart from each other throughout the array. The connecting material also serves the important purpose of distributing any force that impinges upon the fabric or any plate or plates in the fabric among the surrounding plates, thereby taking the entire load of the impinging force off any one plate or group of plates. This property of force distribution enhances the strength of the fabric without requiring more dense plate material, thicker plate material, additional layers of plate arrays, stronger bonding materials, or other strength enhancing properties all of which reduce flexibility, tactility, bendability, twistability, and optional stretchability and increase cost. The connecting material also adds the important property of flexibility of the plate array layer by providing a highly flexible medium between the solid plates. The flexibility is due in a large measure by the fact that the connecting material provides spacing between the plates, which is referred to in this disclosure as the gap. These voids allow bending and hinging between the plates, providing suppleness to the fabric. The connecting material is sometimes referred in this description of the inventive fabric as the continuous portion of a plate layer, while the plates themselves are sometimes referred to as the discontinuous portion of the plate layer.
The material substrate may also be a base material to which the plates are affixed or attached and it may become an integral part of each of the plates in the array. The base material interconnects the plates so that the plates are spaced apart from each other throughout the array. The base material, like the connecting material (although to a lesser degree than the connecting material), may also distribute any force that impinges upon the fabric or any plate or plates in the fabric among the surrounding plates, thereby taking the entire load of the impinging force off any one plate or group of plates. The base material, like the connecting material (although to a lesser degree than the connecting material), also provides flexibility to the fabric. The base material may also be compressible in a direction perpendicular to the sheet of the base material. This property may be desirable in certain applications such as when using the inventive fabric for cleaning, scrubbing, sanding, or other abrading purposes. In these applications, the plates are able to sink into the soft base material and avoid cracking. In other words, base materials acts like a shock absorber.
The connecting and the base materials may support plates on one or both of their surfaces.
In the fabric of this invention, the base material may be combined with and provide support for one or more layers of plates interconnected with connecting material. Alternatively, a layer of plates with connecting material may support itself only or support one or more additional layers of plates with connecting material. The inventive fabric may comprise one or more base materials layered together with one or more connecting materials. The fabric may be comprised of one or more combinations of base material types and connecting material types, each with an array of plates. These layers may be in various stacked arrangements and each layer may have various plate configurations. The base material or the connecting material may be a non-woven or woven fabric. The base material or connecting material may be breathable or may be a liquid barrier.
A representative method of manufacture of a fabric having a single plate layer array on a single connecting material with a single base material begins by positioning connecting material atop base material. A template of the plate layer array is then positioned atop the connecting material. A suitable substance for formation of the plates is printed onto the connecting material through the plate pattern array of the template and the template is removed. Depending on the substance of the plates, the plates may be subjected to curing or other post-patterning treatments.
If the connecting material is an elastomeric material, the degree of stretch of the fabric must be limited. If the fabric over stretches, the spacing between the plates may increase to such a degree that unwanted penetration is permitted. Several arrangements for limiting stretch are available. A non-stretchable fiber may be affixed to the elastomeric connecting material in such a way that in the fabric's unstretched state the fiber has slack. As the fabric stretches, the slack is taken up. At the end-point, where no more slack exists in the non-stretchable fiber, the fiber prevents further stretch of the elastomer. Other means of limiting over stretching involve judicious use of non-stretchable or stretch limiting connecting material at selected portions of the plate array, with due regard for the final use required for the fabric.
The inventive fabric can be fabricated to be worn on the body. Or, the fabric may be used to cover and protect an article or substrate such as cutting, shearing, or slashing instruments from sustaining damage to their sharp-edged surfaces or from causing damage to persons or their surrounding environment.
The inventive fabric may incorporate differing materials as may be necessary to meet the design, strength, dimensional, and other specifications for various applications. A particular feature of the inventive fabric is that while the plates themselves may be hard the connecting material may be highly flexible, bendable, twistable, and stretchable. In other words, the fabric has the property of being locally hard (that is the plates are hard), while retaining global suppleness across an expanse of the fabric due to the flexibility of the connecting material between the hard plates and the softness and flexibility of the base material. The inventive fabric may even exhibit relative softness and conformance to the body or article over which it is draped. The addition of a suitable liquid barrier layer or treatment of the fabric with a liquid resistant substance resists migration of fluids through the fabric.
Further objectives and advantages of the present invention will become readily apparent to those skilled in this art from the following written description of this specification. To illustrate the invention, the DESCRIPTION OF THE INVENTION section of this specification shows and describes certain embodiments of the invention. However, as will be realized, the inventive fabric is capable of numerous arrangements of its constituent elements to meet the requirements of various uses of the fabric, without departing from the scope of the present invention. For example, the fabric may use one or more layers of plate arrays. The geometry of the plates of the fabric may be identical or differ in any one layer or from layer to layer. Various laminations of plate layer arrays, base materials, and connecting materials may comprise the inventive fabric. Accordingly, the drawings and description of the invention set forth in this specification are only illustrative in nature, and not restrictive.
A primary objective of the present invention is to provide a fabric with superior penetration resistance, while at the same time maintaining a high degree of fabric flexibility. Depending on the intended application, the fabric can also be constructed to provide abrasion-resistance, abrasiveness, enhanced grip characteristics, breathability, and other desirable characteristics.
To assist with the understanding of the inventive fabric, an explanation of some of the terms used in this disclosure is provided. The explanation of the terms is not intended to be either a definition or an exhaustive explanation of those terms. A full understanding of those terms is to be garnered from the explanations, the entire written description of the invention, the drawings, and the claims set forth in this disclosure in conjunction with the common understanding of those terms by one skilled in the art.
“Aperture” refers to an area of the fabric not covered by any plate when two or more plate layers are superimposed on each other or, in other words, it is an area of overlapping gaps in a fabric having two or more plate layers superimposed on each other.
“Aperture plates” are plates that usually have a smaller area and cover a smaller expanse of the fabric than guard plates. Generally, aperture plates are positioned to cover apertures not covered by superimposed guard plate layers.
“Base material” refers to a sheet-like material that is generally a non-woven fabric. A layer with connecting material may be supported on a base material. The base material provides resistance to fabric tearing and over all strength to the fabric. The base material may be selected for, among other characteristics, flexibility, strength, bonding characteristics with the plate substance, compressibility, liquid impermeability, chemical resistance, breathability, and washability depending on the use of the final product made from the inventive fabric. The base material provides horizontal and optional vertical integration to the fabric. When the plates are established on the base material, whether or not the base material supports a connecting material, the base material allows the substance of the plates to penetrate into the base material and/or to adhere to the base material. The base material may be, but need not be, penetrated by the plate substance to achieve optimum bonding with the plates. Examples of suitable materials for base material are nylon, polyester, polyaramide, acrylic, and cellulose material.
“Connecting material” refers to a porous flexible material. It may be a loosely woven fabric or a web of fibers or bands. For certain fabrics of this invention, an array of plates is established on a connecting material. For certain inventive fabrics, the connecting material may be supported on a base material. A representative example of a suitable connecting material is polyester chiffon. The connecting material is selected for its porosity and flexibility. It is also selected for its ability to provide a connection between plates in a layer and for its ability to enhance the resistance of a plate to debonding stresses exerted on the individual plate by spreading the debonding forces throughout the array of plates rather than concentrating the debonding forces on a single plate or a few plates. When the plates are established on the connecting material, whether or not the connecting material is supported on a base material, the connecting material allows the substance of the plates or the bonding of the adhesive for the plates to penetrate through the connecting material.
“Fabric” refers to the inventive fabric of this disclosure. It is an arrangement of at least one layer, in which the layer is an ordered array of plates. Each plate array is maintained and stabilized in position by a material. Each plate array may be established on a connecting material, on a base material, or on a connecting material supported on a base material.
“Gap” is an area in a plate layer that is not covered by plates.
“Guard plates” are plates that usually have a larger area and cover a larger expanse of the fabric than aperture plates.
“Layer” refers to an array of plates embedded in connecting or base material. In a plate layer, plates are not directly connected to each other. The connecting or base material maintains the positions of the plates relative to each other in an array and maintains the gap between adjacent plates.
“Plate” refers to an individual plate-like object. A plate may have any suitable shape. A plate is generally planar, but need not be. In a penetration resistant inventive fabric, the plates are constructed of a penetration resistant substance. The plates may optionally have other characteristics, such as enhanced grip and abrasion resistance. The term plate refers to both guard plates and aperture plates.
“Registration” refers to superimposing, or stacking, two or more plate layers in proper relative positions to each other so that the penetration resistant fabric provides maximum cut and puncture resistance against needle-like or knife-like objects. Generally, plate layers are superimposed on each other to minimize the size and spacing of apertures of the fabric.
“Substance” refers to the stuff, matter, or constituent component of which the plates are constructed, as exemplified by an element, compound, alloy or composition. The substance may be tough, hard, and strong, and not friable or brittle depending upon the application. The substance type and the thickness of the plates will differ for needle penetration resistance, for cut resistance, and for resistance to other forces depending on the encountered level of force.
A typical embodiment of the fabric of this invention contains multiple layers of guard plates with the guard plates in each layer connected to a base material or to a base material and an overlay of connecting material. The guard plates are manufactured of a substance selected for its resistance to penetration and optionally for added features of grip enhancement and abrasion resistance. The base material provides overall strength to the fabric, including resistance to tearing and overstretching. It is selected for its flexibility as well as its strength, for its ability to bond with the plate substance, and for other desirable features. Other characteristics may be important for the base material, such as breathability and washability, depending on the use of the final product made from the inventive fabric. The connecting material is selected for its porosity and flexibility. It is also selected for its ability to provide a connection between plates in a layer and for its ability to enhance the strength of the bond between the plate array and the base material.
The composite nature of the inventive fabric makes it possible to realize locally (that is at the plate level) hard, puncture, and cut resistant plate features. At the same time, the fabric may exhibit global (that is overall) softness and flexibility due to the degree of softness and flexibility of the base material and the connecting material chosen for a particular application.
By judicious selection of substances, the fabric of this invention can resist a wide range of sub-ballistic forces. The fabric is not designed to resist ballistic forces due its inherent design. The large size and extremely high speed of a ballistic force dictates that ballistic impact involves a large degree of fiber tensile extension and stress wave energy dissipation over an area much larger than the size of a bullet. This makes it critically important that ballistic resistance materials must use fibers with high tensile strength, modulus, and energy to break. A similar situation occurs in puncturing of a fabric by a blunt probe. If the tip size of the blunt probe is sufficiently large, the dominant mode of penetration is stretching and breaking of fibers in the fabric. In the process of needle penetration through a fabric, the sharp tip of a needle can penetrate fabric simply by opening up gaps between weaves. A needle penetration process, therefore, does not necessarily involve tensile extension and breaking of fabric fiber. The design philosophy must be fundamentally different.
To provide penetration resistance, one approach is to have a high level of coverage by penetration resistant plates to increase the probability that a needle or other penetrating instrument will encounter puncture resistant plates. The fabric of this invention will provide 100% plate coverage with three layers of plates. The term “plate” refers to both guard plates and aperture plates. Typically, the three plate layers must also be sized and positioned correctly in order to achieve 100% coverage. The fabrics illustrated in
FIGS. 27 shows a method of making a reinforced guard plate layer using wire mesh. Typically, the wire mesh would be metal, but other substances may be used depending upon the application. The fabric of
In this disclosure, embodiments of the inventive fabric are sometimes referred to by the designation SF11, SF12, SF13, and so forth for ease of reference.
An octagon-and-square plate array has the benefit of much reduced sensitivity in fluctuation of the aperture-size when the registration of layers is away from its predetermined initial position, which allows for a larger registration tolerance. For example, in the equilateral octagon-and-square guard plate two layer array of
A polymer resin is suitable for use as the plate substance for the inventive fabric. In choosing a polymeric resin as a plate substance, it is important to ensure a strong bond between the polymer resin and the base material. A suitable polymer resin for construction of the plates is a one-part heat-curable epoxy resin formulated to (i) provide puncture and cut resistance appropriate to the application of the fabric, (ii) be screen printable, (iii) be flexible and yet strong, (iv) bondable to the base material, and (iii) have good shape definition during printing and curing. Such resins are readily formulated to meet these criteria and are available from, for example, Fielco Industries, Inc., 1957 Pioneer Rd., Huntingdon Valley, Pa. 19006, which has formulated a resin that meets the characteristics set forth in this paragraph and has given it the designation: TR21. And TR84. A suitable base material is a nonwoven polyurethane and nylon synthetic leather, such as Amara®, available from Clarino America Corp., 489 Fifth Ave., 31st Floor, New York, N.Y. 10017. Other suitable materials include woven or non woven materials, nylon, polyester, polyaramide, acrylic, cellulosic, and similar materials.
The guard plates and the aperture plates are very thin and of a substance chosen to resist a penetration force equivalent to that exerted by a cutting force of the level and type for which the fabric is to be used and for which it is designed.
It has been known that, if polymer resin plates are printed directly onto a base material, they tend to debond easily when the plate is subject to shear or abrasion forces during use. However, it has been unexpectedly discovered according to this invention that, if a layer of connecting material is laid on the base material before establishing the plate layer array, the bonding between the plate layer and the base material is markedly improved. For example, a connecting material is arranged atop a base material. A plate layer array is established by placing a template of the plate layer array atop the connecting material and printing the plate layer array with a suitable polymer resin. The polymer resin completely penetrates through the connecting material and continues to penetrate through a surface portion of the base material. The connecting material thus becomes an integral part of the plate layer array. Due to the interconnection between the individual plates of the array by the connecting material as an integral part of the plates and of the plate layer array, any force exerted on the fabric surface that would tend to debond an individual plate is dissipated by the connection of the individual plates to each other through the connecting material.
A connecting material may be any porous and flexible material, which may also be characterized as a web. The connecting material may be any such material into which the plate material may be integrally bonded. A suitable connecting material is any typical commercially available polyester chiffon. The connecting material spreads any force, including an abrasive force, applied to the surface of the fabric between neighboring plates. The lateral connection afforded by the connecting material reduces the debonding stress borne by each individual plate. The connecting material is chosen for its ability to provide an interconnection between plates in a layer, and for its ability to enhance the strength of the bond between the plates and the base material. Because the plates are formed onto and through the connecting material, the presence of a connecting material has the added benefit of reenforcing each plate with a continuous fiber network. When a connecting material is used together with a base material, the fabric demonstrates enhanced puncture and cut resistance.
Fabrics according to the present invention are able to provide needle puncture resistance, against a needle impinging upon the fabric at an angle of approximately 90° to the fabric surface and at angles substantially less than 90°. The potential for penetration can be greater from a low-angle needle or similar probe. A low-angle needle may have a greater tendency to lift a plate off the fabric surface or to penetrate through an aperture and then below the top fabric layer. Maintaining a minimal gap size between plates, a minimal open area in superimposed layers, and a minimal vertical distance between layers of the fabric enhances penetration resistance against even low-angle penetration.
The minimal gap size depends upon the material used for the guard plate and the thickness of the guard plate. Generally, the gap size should not be smaller than the guard plate thickness to maintain flexibility. The thickness of guard plates range from 5-20 mils for polymers and 1-5 mils for metal. The vertical distance between layers should be below a couple of mils to lower the probability of angle penetration while still maintaining adequate adhesive bonding strength between layers.
The various characteristics of the fabric of the invention must be in balance with each other to ensure the desired global flexibility of the fabric.
Another approach to achieving penetration resistance is to use just one layer of penetration resistant plates. This approach has the advantage of potentially greater fabric flexibility and simplicity in manufacturing than the multi-layer approach. The absence of multiple layers of plates leaves a higher percentage of gap space in comparison to the multi-layer approach. However, when the gap size is narrowed sufficiently in relation to the typical probe tip geometry and dimensions, a significant level of penetration resistance may be expected even at the gap locations.
The tip of a 21 gauge medical needle is cut at an angle of 26 degrees as is shown in
A two-step process of lamination (bonding) and etching is used to make a one-layer fabric with metal guardplates. A metal sheet (e.g. 2-5 mil thick stainless steel) is bonded to a flexible substrate (such as chiffon fabric and synthetic leather Amara) with a flexible bonding agent (e.g. polyurethane). Photo resist films are applied on both sides and the metal is etched to leave disconnected guardplates. The etching technology can control the gap size with precision down to the thickness of the metal sheet. This produces the combination of extremely strong guardplates with very narrow gaps.
One hundred percent plate coverage is not as important for cut resistance as for puncture resistance. For a cut resistance fabric it is important that the plates be made of a cut resistant material. Metal, ceramic, and polymer resins reenforced with mineral or metal particles are examples of good cut-resistant substances for the plates of this inventive cut resistant fabric. A suitable polymer resin is a one-part heat-curable epoxy resin, which can be formulated, to meet the needs of various fabric applications, by Fielco Industries, Inc., 1957 Pioneer Rd., Huntingdon Valley, Pa. 19006 (as previously stated, designated by Fielco as TR21) or a metal-filled or mineral-filled epoxy putty, such as Devcon Plastic Steel® Putty (A), manufactured by ITW Devcon, 30 Endicott St., Danvers, Mass. 01923.
It is also important for cut resistance that there are no straight-line areas of the fabric that are uncovered by plates. Therefore, this is a determining factor in the choice of the (i) patterns of the plates, (ii) shape of the plates, (iii) size of the plates, and (iv) size of the gap between the plates. All of these interrelated factors must be controlled in the design of a fabric embodiment to assure that there are no straight lines of exposed, uncovered fabric, that is, no straight lines of fabric that are uncovered by plates. A hexagon pattern, for example, as seen in the guard plate layers of
Flexibility is another important attribute for a successful fabric of this invention. In a multi-layer fabric, each plate layer must be flexible. The flexibility of the base material and connecting material, the plate geometry and size, and the aperture size between plates all contribute to the flexibility of the fabric. A critical control factor to the overall flexibility of the inventive fabric is the integration of layers, that is, the position of the layers superimposed on each other and the position, density, and substance of the bonding agent. The cured bonding agent must remain flexible. In the SF11 (
In fabrics such as SF15 (
The fabric of this invention can also be constructed to provide a liquid barrier. If the fabric uses a base material, the base material itself can be liquid proof or can be treated with any suitable commercially available liquid-proof coating, such as silicone and polyurethane. Alternatively, the fabric itself can be constructed with an additional liquid proof barrier layer, such as latex or polyurethane.
Depending on the environment within which the fabric of this invention is used, breathability may be another important characteristic of the fabric. A fabric constructed with layers using only connecting material is inherently breathable, because the connecting material in the gaps between the plates is very porous. For fabrics constructed with layers using a base material, the fabric is breathable if the base material is chosen to be breathable.
The local (hard) and global (supple) properties of the fabric facilitate incorporation of other desirable features into the fabric, in addition to the penetration resistant features described above. For example, polymer resins for the plates can be chosen to maximize static friction between the fabric and wood, steel, fish, glass, or other surfaces. Static friction is particularly important in gloves for industrial uses and outdoor sport uses where grip is an important consideration. Coating the polymer resin plates with a high coefficient of friction material can further increase grip strength. Therefore, gloves can be customized for each specific application by choosing a plate material to suit the frictional needs of the application. Resins may be readily formulated to meet a variety of high grip strength applications. Fielco readily formulated a resin that provides good grip for stainless steel surfaces. Devcon provides a good resin for galvanized steel surfaces. Another example of a useful product of the fabric of this invention is a flexible cleaning cloth with specialized imprinted plates designed for optimum abrasiveness. For example, a polymer with a metal filler may be used to provide an abrasive surface. An abrasive fabric of this invention may be a single plate layer array established on base material with connecting material overlay. A glove, mop, cloth, pad, or similar item fabricated of such a fabric is suitable for cleaning relatively hard surfaces. Such an abrasive fabric may also serve for wet or dry sanding. Again, the abrasion characteristics of the plates and the flexibility of the base material of the inventive fabric can be separately optimized according to the use characteristics desired in the final product. The suppleness and compressibility of the base material has been found to be of particular importance for design of a fabric used for abrasive purposes. As the abrasive fabric moves across the surface to be abraded, the individual plates are allowed to compress into the base material and thereby conform to the deviations in the abraded surface. Without this compressibility feature, the abrading fabric would not be as efficacious in its ability to smoothly move over the abraded surface and perform function whether it be cleaning or sanding.
The following detailed description of the structure of various embodiments of the penetration resistant fabric of this invention enables any person skilled in the art to make and use this invention and sets forth the best modes contemplated by the inventor for carrying out the invention. Various modifications of the described embodiments of the inventive fabric, however, will be readily apparent to those skilled in the art because the principles of the present invention are defined in this written description.
In this disclosure, embodiments of the fabric are sometimes referred to by the designation SF11, SF12, SF13, and so forth for ease of reference.
The SF11 fabric can be manufactured by attaching a chiffon fabric to a metal frame. A stencil with a pattern in the form of an array of plates (such as hexagons) is then placed over the chiffon. The chiffon is backed with a release film and printed with a polymer resin (such as can be formulated by Fielco or Devcon as described in more detail in this specification) through the stencil to form guard plates or aperture plates on the chiffon. The resin usually penetrates through the chiffon to mechanically lock the plates into the chiffon. The printed resin is then cured (by heat, room temperature, moisture, or ultra violet light as may be required by the resin's specification) and the release film is removed to form a plate layer. Multiple layers of plates may be stacked together, depending upon the design parameters required by the application for which the fabric is to be used. To achieve proper registration of the layers to each other so as to minimize the inter-plate spacing (that is to minimize the number and size of holes extending through the entire stack of layers), the metal frames contain registration holes for properly offsetting layers. This method of manufacture is applicable, with certain variations or additional steps that would be readily apparent to one skilled in the art, for manufacture of other fabric embodiments described in this specification. An example of an alternate for manufacturing a plate layer uses a photo-mask process for forming the plates rather than the stenciling method. In this method a sheet of connecting material is attached to a metal registration frame and the connecting material is then attached on top of a release film. The ultra violet curable resin is then is poured on the frame side of the connecting material. Another release film is placed on top of the resin and the resin is spread to form a thin film with the connecting material embedded in it. The film thickness is typically in the 5-10 mil range and can be controlled by the application of pressure on a blade used to spread the resin. A photo mask is then placed on top of the release and the whole assembly is secured together using clips. The resin not blocked by the mask is then cured under an ultra violet lamp. The uncured part of the resin is then washed away using an organic solvent, such as alcohol. After drying, a plate layer is obtained. The photo mask process has the advantage of better resolution control of the gap size between parts, as compared to conventional screen-printing. Using the same photo mask process, the ultra violet curable resin may be pre-mixed with glass fibers. After the washing process, some glass fibers may remain in the gap between the plates. An additional etching step is used to etch away these glass fibers. The plates reinforced with glass are strengthened and more puncture and cut resistant.
Manufacture of the SF 15 fabric and other embodiments of fabric of this invention having a base material are made using the process as described in connection with the SF 11 fabric, except that the base material is first attached to the metal frame and the connecting material is laid on top of the base material. The resin for the plates is stenciled onto the composite of the connecting material and the base material. The resin penetrates the connecting material and attaches to the base material upon curing. The same process can be repeated on the opposite side of the base material to make another opposing plate layer.
Alternatively, a fabric of this inventive embodiment may be assembled without the connecting material for the second layer 72 of circular aperture plates 74. The second layer 72 may omit the connecting material 15, because the aperture plates 74 are not subject to debonding stresses, as they would be if they were surface plates. With or without the connecting material, the second layer 72 of circular aperture plates 74 are established on a first sheet of base material. The second sheet of base material is then pressed onto the layer 72 and the entire assembly is cured to the degree necessary.
A connecting material 15 overlies the surfaces of the base material 47, as seen in
Interposed between the layers 46 and 44 is a base material 47, as seen in the cross-sectional view of
The fabric of
An alternative method of bonding the metal sheet 155 to the connecting material 15 by completely covering the connecting material 15 with the bonding agent 153 as described in the previous paragraph is to spot-bond the connecting material to the metal sheet only at the locations where the guard plates will be positioned in the completed fabric 150. With this method of bonding, a strong, usually rigid epoxy structural adhesive has been effective. No spot bonding adhesive is applied at the gap locations. The bonding agent 153 can be stenciled onto the connecting material 15, after which the metal sheet 155 is bonded to the connecting material 15 before the bonding agent 153 sets. Although, the spot bonding approach results in a fabric 150 that suits certain design criteria, the preferred bonding method is to use a continuous layer of bonding agent 153. The spot bonding method limits the accuracy of the guard plate 152 size and shape and the gap 154 between the guard plates 152 due to the inherent variations in the rheology of the bonding agent adhesives used for spot bonding and the process of screen printing those adhesives. Use of the continuous application of bonding agent is limited only by the etching process, which is very accurate. Using the continuous application of bonding agent 153 allows the creation of narrow gaps, up to the thickness of the metal sheet 155, between the guard plates. This increases the puncture and pierce resistance of the fabric 150.
To maintain proper flexibility of any of the finished fabric embodiments, it is important that the gaps between guard plates are free from materials that may compress or stretch during flexing of the fabric. Because the guard plate material is usually rigid and inflexible, most of the strain caused by bending the fabric is concentrated in the gap region. Even a soft material in the gap region may significantly contribute to the rigidity of the whole fabric because the strain is amplified at the gap region. Jamming of the neighboring guard plates as the fabric is flexed if the gap is too narrow can also compromise flexibility of the fabric. This jamming of neighboring guard plates occurs when the gap size becomes smaller than the thickness of the guard plate. But with the metal plate in the thickness range of 2-5 mils, it is possible to narrow the gap size between the guard plates to as small as the guard plate thickness without compromising overall flexibility. The narrowing of the gap is a worthwhile goal because the smaller the gap the less chance that a penetrating instrument will penetrate the fabric of this invention. Etching technology is sufficiently precise that a gap as thin as a metal sheet thickness in the range of 2-5 mils can be fabricated. A 2-5 mil gap size is much smaller than the typical medical needles, which range from 13 mils for insulin needles to 31 mils for a 21 gauge needle 156, which is shown in
A 21 gauge medical needle, as illustrated in
A material suitable for the metal plates is stainless steel sheet 2 having a 2 to 5 mil thickness. H.B. Fuller UR-2139 and Ciba 2040 polyurethane adhesives have been found to be effective. These adhesives are chosen for their flexibility, their bonding strength, and their ability to maintain good bonding strength after the etching process. An example of the base fabric used with the metal plate construction, with or without wire mesh reinforcement, is Amara. A suitable connecting material for embedding in adhesive is chiffon fabric.
An SF15 fabric, as illustrated in
Test Equipment and Procedures
Needle puncture testing was performed on samples of fabric described in this specification using an Imada puncture resistance tester, model number DPS-44R, available from Imada, Inc., 450 Skokie Blvd., Suite 503, Northbrook, Ill. 60062. The puncture tester is capable of measuring forces in the range of 0-44 pounds. A fabric sample is placed on top of the tester's metal base. A needle (typically 20 mils in diameter with a cone shaped tip) is attached to the tester probe, which is positioned vertically above the fabric sample. The probe moves toward the fabric sample with a fixed velocity (for example, 80 mm/minute). The puncture tester measures and records the peak force attained during the puncture attempt. Each test uses a fresh probe. The standard test is at a 90° angle to the surface of the fabric sample. The tester is adjustable to vary the angle at which the test needle impinges upon the fabric sample.
A cut resistant tester was designed and constructed to test the cut resistance of the fabric claimed in this specification. The cut resistance tester is similar to the standard cut resistance tester described by ASTM F 1790-97, Standard Test Method for Measuring Cut Resistance of Materials Used in Protective Clothing. A fabric sample is mounted on a brass sheet covered wooden drum of the tester. A razor blade, attached to a lever arm of the cut tester, rests against the fabric surface. A predetermined weight is applied to the lever, creating a known cutting force. The drum is hand rotated at a slow, fixed speed so the razor blade cuts against the fabric and parallel to it for a distance of 4 inches. If the razor blade cuts through the sample within the 4 inches, the threshold cut-through force is measured and recorded. If the sample is not cut through within the 4 inches, the test result is recorded as “no-cut.” A new razor blade is used for each test.
The SF15 fabric is illustrated and described above with reference to
Using a grabbit needle as a probe, the puncture resistance of the SF15 sample fabric was determined to be 3.5±0.7 lbs. for a needle impinging the fabric at a 90° angle of attack and 3.1±0.7 lbs. for a 30° angle of attack. The cut resistance measured to be above 7 lbs. A grabbit needle or pin is a pin found in an office supply store. It is about 20 mils in diameter with a cone shaped tip. It is used as a puncture probe because of its sharpness and thinness.
The SF16 fabric is illustrated and described in this specification with reference to
The SF16 sample was puncture tested using a grabbit pin. Under a 2.0-lb. force, no penetration was observed at 90°, 52°, and 30° angles of attack. The cut resistance of the sample was 14 lbs.
The SF17 fabric is illustrated and described in this specification with reference to
Using a grabbit needle as a probe, the puncture resistance of this SF17 fabric sample measures to be 3.4±0.7 lbs. for a 90° angle of attack, and 3.1±0.7 lbs. for a 30° angle of attack. The cut resistance measures to be 8 lbs.
The SF22 fabric is illustrated with reference to
The layers 44, 46, and 72 are bonded together, in properly registered positions, as shown in
The puncture resistance for this fabric, using a grabbit pin as the probe, measured to be 3.5±0.5 pounds for a 90° angle of attack and 3.0±0.5 pounds for a 30° angle of attack. The cut resistance measured to be 9 pounds.
Guard plate layers of the wire mesh reinforced fabric are made using the process described in
In the SF16 design as shown is
For bonding, 31 mil diameter adhesive dots are used. They are separated periodically by 0.34 inch. The bonding adhesive is Fleshtex from Zeller International. 10 parts of FleshTex component A and 10 parts of FleshTex component B are mixed and then added to 0.8 parts of Cab-O-Sil flow modifier.
The samples are tested using a 21 guage medical needles with a 30 degree angle of attack. This represents one of the harshest conditions for the puncture test. Four samples were made and 20 puncture tests were done on each sample. The lowest threshold force observed for needle penetration was found to be 1.1 pounds. The average force was 2.26 pounds (the average was based upon 100 data points). The puncture resistance force ranged from 1.1 to 4.0 pounds.
The fabric embodiments of this invention have application for protective garments for individuals working in occupations exposed to potentially injurious penetration, such as public safety officers, machinists, butchers, surgeons, and the like. Depending upon the thickness of the fabric, dimensions and styles of the plates, and the substances and materials from which the fabric of this invention is constructed, the protective garments may have properties ranging from resistance to stabbing and cutting, up to resistance to needles. When the fabric of this invention is used for penetration and puncture resistance, the plates are made of a hard penetration or puncture resistant substance. Preferably, the penetration and puncture resistant apparel or item made from the fabric of this invention will have the hard plates of the array oriented toward the expected source of penetration or puncture. Sport and outdoor apparel of fabric according to this invention may be insect and snake bite proof. Apparel from the present inventive fabric may be suitable for specific activities and environments calling for protection from penetration or puncture, including apparel for riding open uncovered vehicles such as motorcycles, industrial safety apparel, underwater diving wear, and penetration or puncture resistant footwear and head coverings. Other items that require resistance to penetration are made from fabric of this invention, including liquid-retention liners for oil tankers, ponds, landfills, swimming pools and tires. Articles requiring penetration-resistance, including inflatable rafts, light watercraft, such as canoes, kayaks and racing shells, or air mattresses may be fabricated from fabric of this invention. Apparel for other occupations as well as for applications in the medical and dental fields will require differing penetration and puncture resistant substances and material types. Differing thickness and dimensions of the plates are required, since the forces that come to bear upon the fabric will vary.
For medical gloves, the sizes and shapes of the guard plates and the aperture plates and the substance of which they are made, may vary, according to the particular procedures to be performed and differing conditions. It may not be necessary to fortify an entire glove with a puncture resistant fabric of this invention. The fabric may strategically reinforce only high-risk zones.
This fabric is not dependent upon specific shapes or dimensions of the plates. The fabric is scaleable to meet widely varying possible uses. The choice of shapes and dimensions, and the substance and material of which they are manufactured, are dependent upon the application and are determinable by routine engineering calculations. The fabric of the invention, when manufactured of substances and materials of suitable strength, resistance, and dimensions forms a flexible, cut, puncture, and pierce resistant enclosure for biohazardous and potentially flammable and/or explosive liquids, including gasoline and other petroleum or fuel products. Such flexible enclosures find use as liners in various types of tanks or similar liquid reservoirs.
The substances of which the plates are manufactured are currently available as off-the-shelf goods or in the case of resin are readily formulated by resin manufacturers to meet design parameters required of the fabric for use in various applications. The substances can be, for example, metal (such as stainless steel or titanium), metal alloys, ceramic, polymers, high strength composites (such as carbon fiber or glass composites), or glass. Any other substance may be used that resists the specified puncture, piercing, and cutting forces at the chosen thickness necessary to achieve the characteristics desired for the application. Other examples of suitable products include epoxy or acrylate resins, such as Darocur®, Epon®, or Ebecryl®; other thermoset resins whether; and mixtures of such resins with other polymers and optionally with various suitable curing agents. Any substance should preferably not be friable or brittle. When the fabric forms a liquid enclosure or receptacle or is used in a liquid environment, the selected substances and materials for the fabric should be resistant to chemical or physical action of the contained liquid.
The process of assembling the fabric of this invention uses currently available production technology and the novel method of printing plates onto a base material, as described in this specification.
The surfaces of any of the plates described in this disclosure may be planar, concave, convex, or any combination thereof, or a specially constructed surface to meet the needs of a particular application. The guard and aperture plates used in the inventive fabric for differing applications will have a thickness sufficient to resist the piercing or cutting force that the fabric is intended to resist. The plates of different layers of the same inventive fabric may each be made of different substances.
A connecting material is any material, which when interconnected between the plates of the fabric, maintains a predetermined spatial relationship of the plates within the fabric and within a prescribed range of motion of the plates relative to one another. To do so, the connecting material should be flexible. The connecting material may be continuous or have certain selected discontinuities, as long as it performs the needed function of maintaining and connecting the array of plates in the fabric. Any discontinuities in the material may be chosen to enhance the properties of flexibility, bendability, and twistability, and, optionally, stretchability in the fabric or in the useful article made with the fabric. Any discontinuities in the material must be so chosen and located that they do not compromise the required penetration resistance of the fabric either locally or globally or of the useful article constructed of the fabric. Such discontinuities must also be so chosen and located that they do not deleteriously affect the structurally integrity of the fabric or allow any portion of the array to separate. The material may be elastomeric or non-elastomeric. The material is chosen with regard to promoting the desired three degrees of freedom of movement of the fabric of this invention, including flexibility, bendability, and twistability. The material may also be chosen to enhance the desired properties of elasticity and stretchability in the inventive fabric. A stretchable material, such as an elastomer, is an example of a flexible material suitable for performing this function. However, a non-stretchable material is suitable for certain applications. The material may be man-made, naturally existing, or blends of the two.
As with other embodiments set forth in this specification, other variations are appropriate to meet the functional and utilitarian needs of the application. Such variants are choices that come within the spirit and scope of this invention.
This specification has described and illustrated various embodiments of the penetration resistant fabric of the invention. Various arrangements of plates and layers have been described. However, these illustrated and described arrangements are not intended to be the only arrangements for implementing and achieving the objectives of the present invention, nor are they the only possible embodiments encompassed by this invention. This invention is capable of modification within the scope of the inventive penetration resistant fabric and, therefore, the invention is not limited to the precise details set forth in this specification. This invention includes all changes and alterations that fall within the purview of the appended claims.