WO1992014608A1 - Penetration resistant articles and method of manufacture thereof - Google Patents

Penetration resistant articles and method of manufacture thereof Download PDF

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Publication number
WO1992014608A1
WO1992014608A1 PCT/US1992/001412 US9201412W WO9214608A1 WO 1992014608 A1 WO1992014608 A1 WO 1992014608A1 US 9201412 W US9201412 W US 9201412W WO 9214608 A1 WO9214608 A1 WO 9214608A1
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WO
WIPO (PCT)
Prior art keywords
article
fibers
comprised
fiber
binder
Prior art date
Application number
PCT/US1992/001412
Other languages
French (fr)
Inventor
Homan B. Kinsley, Jr.
Original Assignee
Custom Papers Group, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Custom Papers Group, Inc. filed Critical Custom Papers Group, Inc.
Publication of WO1992014608A1 publication Critical patent/WO1992014608A1/en

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F41WEAPONS
    • F41HARMOUR; ARMOURED TURRETS; ARMOURED OR ARMED VEHICLES; MEANS OF ATTACK OR DEFENCE, e.g. CAMOUFLAGE, IN GENERAL
    • F41H5/00Armour; Armour plates
    • F41H5/02Plate construction
    • F41H5/04Plate construction composed of more than one layer
    • F41H5/0471Layered armour containing fibre- or fabric-reinforced layers
    • F41H5/0485Layered armour containing fibre- or fabric-reinforced layers all the layers being only fibre- or fabric-reinforced layers
    • AHUMAN NECESSITIES
    • A41WEARING APPAREL
    • A41DOUTERWEAR; PROTECTIVE GARMENTS; ACCESSORIES
    • A41D31/00Materials specially adapted for outerwear
    • A41D31/04Materials specially adapted for outerwear characterised by special function or use
    • A41D31/24Resistant to mechanical stress, e.g. pierce-proof
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21FPAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F11/00Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H13/00Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
    • D21H13/10Organic non-cellulose fibres
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H13/00Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
    • D21H13/10Organic non-cellulose fibres
    • D21H13/20Organic non-cellulose fibres from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H13/26Polyamides; Polyimides
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H25/00After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
    • D21H25/005Mechanical treatment
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H25/00After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
    • D21H25/04Physical treatment, e.g. heating, irradiating
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H27/00Special paper not otherwise provided for, e.g. made by multi-step processes
    • D21H27/30Multi-ply

Definitions

  • the present invention relates to ballistic and puncture resistant articles of manufacture, as well as to a method of manufacture such articles.
  • the ballistic and puncture resistant articles of the present invention comprise high strength, high melting fibers such as polyaramid fibers.
  • Ballistic and puncture resistant articles formed from high strength fibers such as polyolefin and nylon (polyamide) fibers are known.
  • articles formed from high strength polyolefin fibers are known from a series of U.S. Patents assigned of record to Allied Corporation. These are:
  • Harpell et al patents listed above are particularly directed to ballistic- resistant articles formed by winding a continuous filament of the high strength polyethylene around a steel plate to form a network of parallel fibers. Harpell et al reported this construction was found to be superior to KEVLAR (trademark of Dupont for aramid yarn) in arresting projectile penetration.
  • KEVLAR fibers in the construction of puncture and ballistic resistent materials.
  • Another object of the invention is to provide a method for manufacturing such ballistic and puncture resistant articles that is easily adapted to an industrial scale, preferably by modifying
  • a further object of the present invention is to provide ballistic and puncture resistant articles that offer penetration resistance at least equal to articles of the prior art, but at significantly lower material basis weight, thereby greatly expanding the useful applications for such articles.
  • a ballistic resistant and/or puncture resistant wet-laid, non-woven structure comprised of high strength, high melting fibers, such as aramid fibers, and a binder which binds the fibers.
  • the degree of binding of the fibers and the basis weight of the wet-laid, non-woven structure are such as to impart penetration resistance to the structure.
  • the high strength, high melting fibers are KEVLAR aramid fibers, i.e., fibers of poly (p-phenylene
  • the structures are prepared using a wet-laid paper making technique, thereby permitting
  • the penetration resistant wet-laid, non-woven structure comprises as the binder a second fiber, e.g., an acrylic fiber, which is heat bondable to the surface of the high strength, high melting fibers.
  • the final structure is achieved by subjecting the wet-laid, non-woven structure to a heat bonding step.
  • the resulting wet-laid, non-woven structure can be used in the manufacture of a variety of
  • penetration resistant articles e.g., vests, gloves, jackets, wall coverings and structural panels.
  • the penetration resistant structures according to the invention are formed using conventional papermaking techniques, such as passing an aqueous slurry of aramid fibers and binder onto an endless wire screen, followed by dewatering and drying of the thus-formed sheet.
  • conventional papermaking techniques such as passing an aqueous slurry of aramid fibers and binder onto an endless wire screen, followed by dewatering and drying of the thus-formed sheet.
  • the penetration resistant structure of the present invention is therefore a wet-laid, non-woven structure comprised of a high strength, high melting fiber and a binder therefor.
  • Aramid fibers are the preferred high strength, high melting fibers for use in the structures of the present invention, with KEVLAR aramid fibers (KEVLAR being a trademark of E.I. DuPont de Nemours) being most preferred. While aramid fibers such as KEVLAR aramid fibers will be used in describing the preferred embodiments of the present invention, it should be understood that the scope of the present invention is intended to
  • high strength, high melting fibers which in general have a tenacity of at least 15 grams/denier, more preferably at least 20 grams/denier, an energy- to-break of at least 18 Joules/gram and a melting point of at least 200°C.
  • specific examples of such fibers include not only KEVLAR aramid and aramid copolymer fibers, but also polybenzobisthiazole (PBT) fibers, polybenzoxazole (PBO) fibers, liquid
  • Aramid copolymer 28 Does not melt 55
  • polyvinyl alcohol Two important factors in achieving a structure exhibiting penetration resistance in accordance with the present invention are the basis weight of the structure and the degree of binding which occurs. Both of these factors are affected by the relative amounts of fiber and the particular binder used.
  • the aramid fibers comprise a major amount of the wet-laid, non-woven structure, and more preferably at least 60% by weight, and most preferably at least 70% by weight.
  • the two foregoing factors are important in achieving penetration resistance as it is believed that the structure of the present invention works because of its unique capability of absorbing energy.
  • the degree of binding it is important to realize that the fibers cannot be too strongly bound by the binder, or the fibers are believed to simply break when struck by a bullet. If the fibers are too weakly bound by the binder, the fibers of the
  • penetration resistance for the purposes of the present invention is meant that a sheet of the material of the present invention will stop a
  • the relative amounts of fiber and binder used in preparing a structure of the present invention will vary based upon the particular binder used and the ultimate desired basis weight of the structure.
  • the binder can be any component, fibrous or non-fibrous, which can bind the fibers. Generally, the binding is achieved through a bonding of the binder with the fibers, however, the binding can also be purely physical or mechanical.
  • a fibrous binder is preferably a fiber which can be heat bonded to the surface of the matrix fiber, e.g., aramid fiber. Any suitable fiber, preferably synthetic, can be used as the binder fiber,
  • the wet-laid, non-woven penetration resistant structure comprises from about 70-80 wt % aramid fiber and from about 20-30 wt % acrylic fiber.
  • the last step in preparing the penetration resistant material of the present invention is to heat bond the non-woven material.
  • This heat bonding step can be achieved by any conventional technique, e.g., heating in an oven.
  • the temperature necessary to achieve heat bonding will vary depending on the second fiber employed.
  • non-fibrous binders examples include, for example, polyvinyl alcohol.
  • polyvinyl alcohol can be added as a powder to the furnish in preparing the wet-laid, non-woven structure.
  • Other powder or particulate binders can also be used.
  • the length of the aramid fiber used can vary, with about 3/4 inch being the most preferred length due to its availability and success achieved using such fiber. In general, as the length of the fiber increases, it is preferred that the relative denier of the fiber increases. Since longer fibers have more contact points, less binder may also be required to achieve optimum performance.
  • Refinement of the binder fiber may also warrant some consideration, as it goes to the bonding ability of the binder fiber with the aramid fibers.
  • 120 CSF (Canadian Standard Freeness, TAPPI T 227 om-85) acrylic fiber is preferred in general to 376 CSF acrylic fiber.
  • additives such as surfactants, can also be employed in the furnish.
  • the structures prepared can be used in the manufacture of many different penetration resistant articles of manufacture. Such articles generally incorporate the structure of the present invention as one of many layers.
  • the structure can be combined or covered with layers of fabric, paint, wallpaper or other synthetic polymers in the manufacture of vests, gloves, jackets and structural panels.
  • the method for manufacturing the non-woven structures of the present invention invokes the use of a foam furnish.
  • a foam furnish for it has been found that an excellent product is achieved when employing a foam furnish as the foam is believed to prevent entanglement of the fibers, which can cause lumps in the final material.
  • the use of a foam furnish in preparing a non-woven fibrous web is well-known to the art, and any of the conventional
  • hydroentangling process in preparing the wet-laid, non-woven web of the present invention.
  • the hydroentangling technique is generally employed prior to any activation of the binder, e.g., whether drying or heat-bonding.
  • Hydroentangling is a process for producing nonwoven fabrics by impinging a plurality of fine columnar streams of a fluid, such as water or air, onto a fibrous web carried by an apertured or patterned conveying means. There is thus produced a felt-like material in which even relatively short fibers can be mechanically intertwined without the d ⁇ unaging effects of needling.
  • a fluid such as water or air
  • U.S. Patent No. 3,485,706 the disclosure of which is hereby expressly incorporated by reference, to the extent not inconsistent
  • hydroentangled fabric is produced wherein the
  • apertures in the fabric correspond to knuckles in the wire screen used to support and convey the fibrous web.
  • Patterned supporting means are disclosed for imparting to the resulting hydroentangled fabric a desired ornamental appearance.
  • Handsheets were prepared, whose formulations were both within and without the scope of the present invention, and subjected to ballistic testing to determine their penetration resistance.
  • Handsheets were prepared by the procedure defined in TAPPI T 205 om-88 with the following modifications.
  • the sheet machine was of the Noble Wood (eight inch by eight inch) design. Approximately 4.03 grams of the fiber and binder were added to the British disintegrator to form a 60 pound per 3000 square foot basis weight handsheet.
  • the sheet was formed on a wire mesh which had been placed on top of the fixed wire mesh in the handsheet machine.
  • the wet sheet and wire was transferred to a Noble Wood wet press.
  • the sheet and wire was pressed in between wet felts as a press pressure of 50 pounds per inch width.
  • the dewatered sheet was then removed from the forming wire and dried on a steam heated drum. This was followed by heat bonding where noted at a suitable temperature.
  • the handsheets thus formed measured 8 inches by 8 inches square, and were formed so as to have a basis weight of 60 pounds per 3000 square feet.
  • the specimens tested could easily be increased 2, 4 or 8 times by folding one of these sheets once, twice or three times, respectively.
  • the specimens tested thus tend to have basis weights increasing by multiples of eight, because the basis weight of a specimen was generally increased y adding an additional 8 inch by 8 inch sheet that had been folded three times.
  • the specimens tested were backed either by plywood or by clay. The first tests were run with plywood as the backing. When plywood backing was used, the plywood had a hole where the bullet was expected to pass (or not pass, depending on whether the specimen stopped the bullet). Clay backing was also used, primarily since modeling clay is the backing used for determining the ballistic
  • the muzzle velocity of these bullets is about 1440 feet per second.
  • the target was located about three feet from the muzzle of the rifle.
  • Pulpex is a trademark of Hercules Corporation for their short fiber polyethylene synthetic pulp. The Pulpex was used in its commercially available form.
  • KEVLAR is a trademark of E.I. DuPont de
  • Nemours Co. for their aramid fiber.
  • the cut length of the aramid fiber used was 3/4 inch.
  • "Melty” is a 4 denier x 5 mm co-polyester binder fiber available from Unitika of Japan.
  • 87PW061 refers to a polyacrylamide aqueous emulsion available from Nalco, and is a water
  • AT-2 is a polyurethane resin available from Rhom & Haas and is used as a water thickener and dispersing agent.
  • AOK is an alpha-olefin sulfonate surfactant, available in flake from Arco.
  • CasChem 318 refers to a nonionic surfactant wetting/dispersing agent available from Cas Chem.
  • L62 refers to Plurionic L62, which is a polyoxypropylene/polyoxyethylene block copolymer useful as a wetting/dispersing agent, marketed by BASF.
  • NVF is a binder fiber supplied by Chori
  • Spongid is a high molecular weight polyethylene fiber supplied by Allied Fiber of Allied Signal
  • Marathon Softwood is a Northern Softwood kraft pulp manufactured by James River Corporation.
  • Basis Weight is in units of lb/3000 ft 2 , and refers to the basis weight of the specimen tested.
  • the bullet would sometimes penetrate fairly deeply into the clay backing, yet fail completely to rupture the paper-like structure of the specimen.

Abstract

Provided is a penetration resistant article which comprises a particular wet-laid, non-woven structure. The wet-laid, non-woven structure is comprised of high strength, high melting fibers, such as aramid fibers, and a binder for binding the fibers. The binding of the fibers and the basis weight of the wet-laid, non-woven structure are such as to be sufficient for imparting penetration resistance to the structure. The resulting structure, and article in which the structure is contained, exhibit excellent penetration resistance, while being manufactured in a most effective and cost efficient manner.

Description

PENETRATION RESISTANT ARTICLES
AND METHOD OF MANUFACTURE THEREOF
BACKGROUND OF THE INVENTION
The present invention relates to ballistic and puncture resistant articles of manufacture, as well as to a method of manufacture such articles. The ballistic and puncture resistant articles of the present invention comprise high strength, high melting fibers such as polyaramid fibers.
Ballistic and puncture resistant articles formed from high strength fibers such as polyolefin and nylon (polyamide) fibers are known. For example, such articles formed from high strength polyolefin fibers are known from a series of U.S. Patents assigned of record to Allied Corporation. These are:
Harpell et al U.S. Patent No. 4,403,012
Harpell et al U.S. Patent No. 4,457,985
Harpell et al U.S. Patent No. 4,501,856
Harpell et al U.S. Patent No. 4,623,574
Harpell et al U.S. Patent No. 4,650,710; and Harpell et al U.S. Patent No. 4,681,792.
Another Allied Corporation patent directed to high strength polyethylene fiber is Kavesh et al, U.S. Patent No. 4,413,110.
These patents describe ballistic-resistant articles of manufacture comprising a flexible network of polyolefin fibers. The Harpell et al patents listed above are particularly directed to ballistic- resistant articles formed by winding a continuous filament of the high strength polyethylene around a steel plate to form a network of parallel fibers. Harpell et al reported this construction was found to be superior to KEVLAR (trademark of Dupont for aramid yarn) in arresting projectile penetration.
The use of aramid fibers in the construction of puncture resistant and/or ballistic resistant
articles is, of course, well-known. Numerous patents disclose the use of polyaramid fibers, and in
particular KEVLAR fibers, in the construction of puncture and ballistic resistent materials. For example, U.S. Patent Nos. 4,864,661; 4,779,290;
4,729,303; 4,608,716; 4,475,248; 4,384,449 and
3,902,196 disclose the use of KEVLAR fibers in the construction of puncture resistant fabrics or
materials. U.S. Patent Nos. 4,380,245; 4,678,702; 4,608,717; 4,574,105; 4,522,871; 4,510,200;
4,485,491; 4,475,247; 4,443,506; 4,428,998;
4,404,889; 4,316,404; 4,292,882; 4,200,677;
4,186,648; 4,181,768; 4,090,005; 4,079,464;
4,057,359; and, 3,958,276 disclose the use of KEVLAR fibers in the construction of ballistic resistant materials, and in particular ballistic-resistant clothing. There remains a need, however, for ballistic and puncture resistant articles capable of arresting projectile penetration more effectively than those discussed above at a given basis weight of ballistic or puncture resistant material, or, correspondingly, that are equally as effective at a lower basis weight. This is particularly true for articles comprised of aramid fibers. There is also a need for a method of making ballistic and puncture resistant materials comprised of polyaramid fibers such as
KEVLAR in a more efficient and cost effective manner.
A major object of the present invention is therefore to provide ballistic resistant articles of manufacture that offer effective penetration
resistance and are prepared in a more efficient and cost effective manner.
Another object of the invention is to provide a method for manufacturing such ballistic and puncture resistant articles that is easily adapted to an industrial scale, preferably by modifying
conventional processing apparatus.
A further object of the present invention is to provide ballistic and puncture resistant articles that offer penetration resistance at least equal to articles of the prior art, but at significantly lower material basis weight, thereby greatly expanding the useful applications for such articles. These and other objects of the present invention will become apparent upon a review of the following specification and the claims appended thereto. SUMMARY OF THE INVENTION
In accordance with the foregoing objectives, there is provided a ballistic resistant and/or puncture resistant wet-laid, non-woven structure comprised of high strength, high melting fibers, such as aramid fibers, and a binder which binds the fibers. The degree of binding of the fibers and the basis weight of the wet-laid, non-woven structure are such as to impart penetration resistance to the structure. It is most preferred that the high strength, high melting fibers are KEVLAR aramid fibers, i.e., fibers of poly (p-phenylene
terephthalamide).
The structures are prepared using a wet-laid paper making technique, thereby permitting
manufacture in a most effective and cost efficient manner. Most preferably, a foam technique is used in the non-woven. formation. Such use of foam has been found to produce a most consistent structure free of lumps.
In a most preferred embodiment, the penetration resistant wet-laid, non-woven structure comprises as the binder a second fiber, e.g., an acrylic fiber, which is heat bondable to the surface of the high strength, high melting fibers. The final structure is achieved by subjecting the wet-laid, non-woven structure to a heat bonding step.
The resulting wet-laid, non-woven structure can be used in the manufacture of a variety of
penetration resistant articles, e.g., vests, gloves, jackets, wall coverings and structural panels. DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENTS OF THE PRESENT INVENTION
The penetration resistant structures according to the invention are formed using conventional papermaking techniques, such as passing an aqueous slurry of aramid fibers and binder onto an endless wire screen, followed by dewatering and drying of the thus-formed sheet. One of the advantages of the present invention is that the penetration resistant structure is quite readily manufactured using a most efficient method and conventionally available
apparatus.
The penetration resistant structure of the present invention is therefore a wet-laid, non-woven structure comprised of a high strength, high melting fiber and a binder therefor. Aramid fibers are the preferred high strength, high melting fibers for use in the structures of the present invention, with KEVLAR aramid fibers (KEVLAR being a trademark of E.I. DuPont de Nemours) being most preferred. While aramid fibers such as KEVLAR aramid fibers will be used in describing the preferred embodiments of the present invention, it should be understood that the scope of the present invention is intended to
encompass high strength, high melting fibers which in general have a tenacity of at least 15 grams/denier, more preferably at least 20 grams/denier, an energy- to-break of at least 18 Joules/gram and a melting point of at least 200°C. Specific examples of such fibers include not only KEVLAR aramid and aramid copolymer fibers, but also polybenzobisthiazole (PBT) fibers, polybenzoxazole (PBO) fibers, liquid
crystalline polyester fibers and extended-chain polyvinyl alcohol fibers e.g., as exemplified in the following Table:
TABLE
Tenacity Energy-to-Break
Fiber (gpd) M.P. ( °C) (J/g)
KEVLAR® 23 Does not melt 41
Aramid copolymer 28 Does not melt 55
(TECHNORA®)
PBT 30 Does not melt 20
PBO 30 Does not melt 19
Liquid crystalline 23-27 300-350 38
polyester
Extended chain 17 228-267 42
polyvinyl alcohol Two important factors in achieving a structure exhibiting penetration resistance in accordance with the present invention are the basis weight of the structure and the degree of binding which occurs. Both of these factors are affected by the relative amounts of fiber and the particular binder used.
Generally, it is preferred that the aramid fibers comprise a major amount of the wet-laid, non-woven structure, and more preferably at least 60% by weight, and most preferably at least 70% by weight. The two foregoing factors are important in achieving penetration resistance as it is believed that the structure of the present invention works because of its unique capability of absorbing energy. With regard to the degree of binding, it is important to realize that the fibers cannot be too strongly bound by the binder, or the fibers are believed to simply break when struck by a bullet. If the fibers are too weakly bound by the binder, the fibers of the
structure will simply pull apart when struck. With regard to basis weight, the lower the effective basis weight the more preferable. The effective basis weight of a particular structure, however, will vary greatly depending upon the particular binder used and the degree of binding employed. Structures having a basis weight of less than a thousand lb/3000 ft2 have been found effective, wherein generally, structures having a basis weight of at least 2000, and 3000 or higher, have been found most effective and still practical. It is the combination of basis weight, degree of binding and particular binder used which must be considered. Thus, achieving a proper balance and combination of the basis weight of the structure and the ratio of particular binder to fiber content, a wet-laid non-woven structure is obtained which exhibits surprisingly good penetration resistance.
By penetration resistance for the purposes of the present invention is meant that a sheet of the material of the present invention will stop a
Winchester high velocity .22 caliber long rifle bullet fired from 3 feet away. The bullet will not pass through the sheet. While ballistic resistance is a very important aspect and advantage of the structures of the present invention, the structures also exhibit excellent puncture resistance with regard to knifes, ice picks and other sharp objects. The overall advantages of the present invention therefore relates to penetration resistance in
general.
The relative amounts of fiber and binder used in preparing a structure of the present invention will vary based upon the particular binder used and the ultimate desired basis weight of the structure. The binder can be any component, fibrous or non-fibrous, which can bind the fibers. Generally, the binding is achieved through a bonding of the binder with the fibers, however, the binding can also be purely physical or mechanical.
A fibrous binder is preferably a fiber which can be heat bonded to the surface of the matrix fiber, e.g., aramid fiber. Any suitable fiber, preferably synthetic, can be used as the binder fiber,
especially if it is heat-bondable. Preferred
examples include acrylic, polypropylene and polyester fibers, with acrylic fibers being most preferred. In a preferred embodiment, the wet-laid, non-woven penetration resistant structure comprises from about 70-80 wt % aramid fiber and from about 20-30 wt % acrylic fiber.
When using a heat bondable fiber, the last step in preparing the penetration resistant material of the present invention is to heat bond the non-woven material. This heat bonding step can be achieved by any conventional technique, e.g., heating in an oven. The temperature necessary to achieve heat bonding, of course, will vary depending on the second fiber employed.
Examples of preferred non-fibrous binders include, for example, polyvinyl alcohol. The
polyvinyl alcohol can be added as a powder to the furnish in preparing the wet-laid, non-woven structure. Other powder or particulate binders can also be used.
The length of the aramid fiber used can vary, with about 3/4 inch being the most preferred length due to its availability and success achieved using such fiber. In general, as the length of the fiber increases, it is preferred that the relative denier of the fiber increases. Since longer fibers have more contact points, less binder may also be required to achieve optimum performance.
Refinement of the binder fiber may also warrant some consideration, as it goes to the bonding ability of the binder fiber with the aramid fibers. For example, 120 CSF (Canadian Standard Freeness, TAPPI T 227 om-85) acrylic fiber is preferred in general to 376 CSF acrylic fiber.
Conventional additives, such as surfactants, can also be employed in the furnish.
In the preparation of the wet-laid, non-woven structures of the present invention, it will be appreciated that in employing a conventional paper-making type process, what might otherwise be a conventional technique interacts with the materials employed to form a resultant product having
properties of penetration resistance that could not have been predicted from the starting materials and technique alone. The structures prepared can be used in the manufacture of many different penetration resistant articles of manufacture. Such articles generally incorporate the structure of the present invention as one of many layers. For example, the structure can be combined or covered with layers of fabric, paint, wallpaper or other synthetic polymers in the manufacture of vests, gloves, jackets and structural panels.
In a most preferred embodiment, the method for manufacturing the non-woven structures of the present invention invokes the use of a foam furnish. For it has been found that an excellent product is achieved when employing a foam furnish as the foam is believed to prevent entanglement of the fibers, which can cause lumps in the final material. The use of a foam furnish in preparing a non-woven fibrous web is well-known to the art, and any of the conventional
techniques can be employed, for example, as described in U.S. Patent Nos. 3,716,449 and 3,871,952 issued to Wiggins Teape Research and Development Limited.
It is also contemplated to use a hydroentangling process in preparing the wet-laid, non-woven web of the present invention. The hydroentangling technique is generally employed prior to any activation of the binder, e.g., whether drying or heat-bonding.
Hydroentangling is a process for producing nonwoven fabrics by impinging a plurality of fine columnar streams of a fluid, such as water or air, onto a fibrous web carried by an apertured or patterned conveying means. There is thus produced a felt-like material in which even relatively short fibers can be mechanically intertwined without the dεunaging effects of needling. One example of a patent describing hydroentangling is U.S. Patent No. 3,485,706, the disclosure of which is hereby expressly incorporated by reference, to the extent not inconsistent
herewith. In this patent, an apertured
hydroentangled fabric is produced wherein the
apertures in the fabric correspond to knuckles in the wire screen used to support and convey the fibrous web. Patterned supporting means are disclosed for imparting to the resulting hydroentangled fabric a desired ornamental appearance.
The invention will be illustrated in greater detail by the following specific examples. It is understood that these examples are given by way of illustration and are not meant to limit the
disclosure or the claims to follow. All percentages in the examples, and elsewhere in the specification, are by weight unless otherwise specified.
A series of experimental handsheets were
prepared, whose formulations were both within and without the scope of the present invention, and subjected to ballistic testing to determine their penetration resistance. Handsheets were prepared by the procedure defined in TAPPI T 205 om-88 with the following modifications. The sheet machine was of the Noble Wood (eight inch by eight inch) design. Approximately 4.03 grams of the fiber and binder were added to the British disintegrator to form a 60 pound per 3000 square foot basis weight handsheet. The sheet was formed on a wire mesh which had been placed on top of the fixed wire mesh in the handsheet machine. The wet sheet and wire was transferred to a Noble Wood wet press. The sheet and wire was pressed in between wet felts as a press pressure of 50 pounds per inch width. The dewatered sheet was then removed from the forming wire and dried on a steam heated drum. This was followed by heat bonding where noted at a suitable temperature.
The handsheets thus formed measured 8 inches by 8 inches square, and were formed so as to have a basis weight of 60 pounds per 3000 square feet. The basis weight of a specimen to be subjected to
ballistic testing could easily be increased 2, 4 or 8 times by folding one of these sheets once, twice or three times, respectively. The specimens tested thus tend to have basis weights increasing by multiples of eight, because the basis weight of a specimen was generally increased y adding an additional 8 inch by 8 inch sheet that had been folded three times. The specimens tested were backed either by plywood or by clay. The first tests were run with plywood as the backing. When plywood backing was used, the plywood had a hole where the bullet was expected to pass (or not pass, depending on whether the specimen stopped the bullet). Clay backing was also used, primarily since modeling clay is the backing used for determining the ballistic
resistance of body armor (U.S. Department of Justice - National Institute of Justice, NIJ Standard
010.03).
The firing was done with a .22 caliber rifle using Winchester high velocity .22 caliber long rifle bullets. According to literature published by
Winchester, the muzzle velocity of these bullets is about 1440 feet per second. The target was located about three feet from the muzzle of the rifle.
The results of these experiments are listed in Table 1 below. In Table 1, the term
"Pulpex" is a trademark of Hercules Corporation for their short fiber polyethylene synthetic pulp. The Pulpex was used in its commercially available form.
"KEVLAR" is a trademark of E.I. DuPont de
Nemours Co. for their aramid fiber. In the Table, the cut length of the aramid fiber used was 3/4 inch. "Melty" is a 4 denier x 5 mm co-polyester binder fiber available from Unitika of Japan.
"87PW061" refers to a polyacrylamide aqueous emulsion available from Nalco, and is a water
thickening agent and dispersing agent.
"AT-2" is a polyurethane resin available from Rhom & Haas and is used as a water thickener and dispersing agent.
"AOK" is an alpha-olefin sulfonate surfactant, available in flake from Arco.
"CasChem 318" refers to a nonionic surfactant wetting/dispersing agent available from Cas Chem.
"L62" refers to Plurionic L62, which is a polyoxypropylene/polyoxyethylene block copolymer useful as a wetting/dispersing agent, marketed by BASF.
"NBF" is a binder fiber supplied by Chori
Company, Ltd. of Chuo-Ku, Osaka, Japan. It is a 3 denier by 5 mm long bi-component fiber.
"Spetra" is a high molecular weight polyethylene fiber supplied by Allied Fiber of Allied Signal
Corporation.
"Marathon Softwood" is a Northern Softwood kraft pulp manufactured by James River Corporation.
"Basis Weight" is in units of lb/3000 ft2, and refers to the basis weight of the specimen tested.
Figure imgf000018_0001
Figure imgf000019_0001
Figure imgf000020_0001
Figure imgf000021_0001
Figure imgf000022_0001
Figure imgf000023_0001
Xn the above table, "N" indicates that the bullet was stopped by the specimen, whereas "P" indicates that the bullet passed through the
specimen. Where more than one designation appears, it indicates that the testing was performed a
plurality of times. When a clay backing was used, the bullet would sometimes penetrate fairly deeply into the clay backing, yet fail completely to rupture the paper-like structure of the specimen.
Nevertheless, if the bullet penetrated more than 0.75 inch into the clay backing, the result was judged "P". The results of these tests are somewhat
qualitative, because the clay backing appeared to improve slightly the performance of the specimen.
While the invention has been described with preferred embodiments, it is to be understood that variations and modifications may be resorted to as will be apparent to those skilled in the art. Such variations and modifications are to be considered within the purview and the scope of the claims appended hereto.

Claims

WHAT IS CLAIMED:
1. A multi-layer penetration resistant article which contains at least one layer comprised of a wet- laid, non-woven structure comprised of aramid fibers and a binder which binds the aramid fibers, with the binding of the aramid fibers in the wet-laid non-woven structure and the basis weight of the wet-laid, non-woven structure being sufficient to impart penetration resistance to the article.
2. The article of claim 1, wherein the aramid fibers comprise a major amount by weight of the wet-laid, non-woven structure.
3. The article of claim 1, wherein the wet-laid, non-woven structure is comprised of at least 60% by weight aramid fibers.
4. The article of claim 1, wherein the wet-laid, non-woven structure is comprised of at least
70% by weight aramid fibers.
5. The article of claim 1, wherein the wet-laid, non-woven structure is comprised of from about 70 to about 80% by weight aramid fibers.
6. The article of claim 1, wherein the binder is comprised of a second fiber which is heat bondable to the surface of the aramid fibers.
7. The article of claim 6, wherein the second fiber is comprised of a polyester, polypropylene or acrylic fiber.
8. The article of claim 7, wherein the second fiber is comprised of an acrylic fiber.
9. The article of claim 1, wherein the binder is polyvinyl alcohol.
10. The article of claim 1, wherein the binder is heat bonded to the aramid fibers.
11. The article of claim 5, wherein the article is comprised of from about 20 to about 30% by weight acrylic fiber bound to the aramid fiber.
12. The article of claim 1, wherein the wet- laid, non-woven structure is hydroentangled.
13. The article of Claim 1, wherein the article is an article of clothing.
14. The article of claim 13, wherein the article is a vest.
15. The article of claim 13, wherein the article is a glove.
16. The article of claim 13, wherein the article is a jacket.
17. The article of claim 1, wherein the article is a structural panel.
18. The article of claim 1, wherein the article is wall covering.
19. The article of claim 1, wherein the fibers are poly (p-phenylene terephthalamide) aramid fibers and comprise a major amount by weight of the wet- laid, non-woven structure.
20. The article of claim 19, wherein the wet- laid, non-woven structure is comprised of at least 60% by weight of said aramid fibers.
21. The article of claim 19, wherein the wet- laid, non-woven structure is comprised of at least 70% by weight of said aramid fibers.
22. The article of claim 19, wherein the wet- laid, non-woven structure is comprised of from about 70 to about 80% by weight of said aramid fibers.
23. The article of claim 19, wherein the binder is comprised of a second fiber which is heat bondable to the surface of the said aramid fibers.
24. The article of claim 23, wherein the second fiber is comprised of a polyester, polypropylene or acrylic fiber.
25. The article of claim 24, wherein the second fiber is comprised of an acrylic fiber.
26. The article of claim 19, wherein the binder is polyvinyl alcohol.
27. The article of claim 19, wherein the binder is heat bonded to said aramid fibers.
28. The article of claim 22, wherein the
article is comprised of from about 20 to about 30% by weight acrylic fiber bound to said aramid fiber.
29. The article of claim 19, wherein the
article is an article of clothing.
30. The article of claim 29, wherein the article is a vest.
31. The article of claim 29, wherein the article is a glove.
32. The article of claim 29, wherein the article is a jacket.
33. The article of claim 19, wherein the article is a structural panel.
34. The article of claim 19, wherein the article is wallcovering.
35. A multi-layer penetration resistant article which contains at least one layer comprised of a wet-laid, non-woven structure comprised of high strength, high- melting fibers and a binder which binds said fibers, with the high strength, high melting fibers having a tenacity of at least 15 grams/denier, an energy to break of at least 18 Joules/gram and a melting point of at least 200°C, and with the binding of the fibers in the wet-laid, non-woven structure and the basis weight of the wet-laid, non-woven structure being sufficient to impart penetration resistance to the article.
36. The article of claim 35, wherein the high strength, high melting fibers are
polybenzobisthiazole fibers, polybenzoxazole fibers, liquid crystalline polyester fiber or extended-chain polyvinyl alcohol fibers.
37. A wet-laid, non-woven structure which is comprised of aramid fibers and a binder which binds the aramid fibers, with the binding of the aramid fibers and the basis weight of the wet-laid, non- woven structure being sufficient to impart
penetration resistance to the structure.
38. The structure of claim 37, wherein the aramid fibers comprise a major amount by weight of the wet-laid, non-woven structure.
39. The structure of claim 37, wherein the structure is comprised of at least 60% by weight aramid fibers.
40. The structure of claim 37, wherein the structure is comprised of at least 70% by weight aramid fibers.
41. The structure of claim 37, wherein the structure is comprised of from about 70% to about 80% by weight aramid fibers.
42. The structure of claim 37, wherein the binder is comprised of a second fiber which is heat bondable to the surface of the aramid fibers.
43. The structure of claim 42, wherein the second fiber is comprised of a polyester,
polypropylene or acrylic fiber.
44. The structure of claim 43, wherein the second fiber is comprised of an acrylic fiber.
45. The structure of claim 37, wherein the binder is polyvinyl alcohol.
46. The structure of claim 37, wherein the binder is heat bonded to the aramid fibers.
47. The structure of claim 37, wherein the structure is hydroentangled.
48. The structure of claim 41, wherein the structure is comprised of from about 20% to about 30% by weight acrylic fiber with the acrylic fiber and aramid fiber being heat bonded.
49. The structure of claim 37, wherein the fibers are poly (p-phenylene terephthalamide) aramid fibers and comprise a major amount by weight of the wet-laid, non-woven structure.
50. The structure of claim 49, wherein the structure is comprised of at least 60% by weight of said aramid fibers.
51. The structure of claim 49, wherein the structure is comprised of at least 70% by weight aramid fibers.
52. The structure of claim 49, wherein the structure is comprised of from about 70% to about 80% by weight of said aramid fibers.
53. The structure of claim 49, wherein the binder is comprised of a second fiber which is heat bondable to the surface of said aramid fibers.
54. The structure of claim 53, wherein the second fiber is comprised of a polyester,
polypropylene or acrylic fiber.
55. The structure of claim 54, wherein the second fiber is comprised of an acrylic fiber.
56. The structure of claim 49, wherein the binder is polyvinyl alcohol.
57. The structure of claim 49, wherein the binder is heat bonded to said aramid fibers.
58. The structure of claim 52, wherein the structure is comprised of from about 20% to about 30% by weight acrylic fiber with the acrylic fiber and said aramid fiber being heat bonded.
59. A wet-laid, non-woven structure which is comprised of high strength, high melting fibers and a binder which binds said fibers, with the high
strength, high melting fibers having a tenacity of at least 15 grams/denier, an energy to break of at least 18 Joules/gram and a melting point of at least 200°C, and with the binding of the fibers and the basis weight of the wet-laid, non-woven structure being sufficient to impart penetration resistance to the structure.
60. A method for preparing a penetration resistant material comprised of aramid fibers, which comprises creating an aqueous slurry of aramid fibers and a binder for the aramid fibers and passing said slurry onto a wire screen to form a sheet, dewatering the sheet and effecting a binding of the aramid fiber s with the binder, with the degree of binding and the amount of aramid fibers used being such that the basis weight of the sheet and said binding are sufficient to impart penetration resistance to the material.
61. The method of claim 60, wherein the binder is comprised of a second fiber which is heat bondable to the surface of the aramid fibers, and the step of effecting a binding of the aramid fibers with the binder comprises heat bonding.
62. The method of claim 61, wherein the second fiber is comprised of a polyester, polypropylene or acrylic fiber.
63. The method of claim 62, wherein the second fiber is comprised of an acrylic fiber.
64. The method of claim 60, wherein the binder is polyvinyl alcohol.
65. The method of claim 60, wherein the material is further hydroentangled.
66. The method of claim 61, wherein the
material is further hydroentangled.
67. The method of claim 60, wherein foam is used in creating the aqueous slurry.
68. The method of claim 60, wherein the aramid fibers are fibers of poly (p-phenylene
terephthalamide).
69. A method for preparing a penetration resistant material comprised of high strength, high melting fibers, with the high strength, high melting fibers having a tenacity of at least 15 grams/denier, an energy to break of at least 18 Joules/gram and a melting point of at least 200°C, which comprises creating an aqueous slurry of said fibers and a binde r for said fibers and passing said slurry onto a wire screen to form a sheet, dewatering the sheet and effecting a binding of the fibers with the binder, with the degree of binding and the amount of fibers used being such that the basis weight of the sheet and said binding are sufficient to impart penetration resistance to the material.
70. The method of claim 69, wherein the binder is comprised of a second fiber which is heat bondable to the surface of said fibers, and the step of effecting a binding of said fibers with the binder comprises heat bonding.
71. The method of claim 70, wherein the second fiber is comprised of a polyester, polypropylene or acrylic fiber.
72. The method of claim 71, wherein the second fiber is comprised of an acrylic fiber.
73. The method of claim 70, wherein the binder is polyvinyl alcohol.
74. The method of claim 69, wherein foam is used in creating the aqueous slurry.
AMENDED CLAIMS
[received by the International Bureau
on 29 June 1992 (29.06.92);
original claims 1,35,37,59 and 69 amended; remaining
claims unchanged (10 pages)]
1. A multi-layer penetration resistant article which contains at least one layer comprised of a wet- laid, non-woven structure comprised of aramid fibers and a binder which binds the aramid fibers, with the binding of the aramid fibers in the wet-laid non- woven structure and the basis weight of the wet-laid, non-woven structure being sufficient to allow the fibers to have a tendency to pull out of the
structure rather than break in order to permit energy absorption by the fibers and impart penetration resistance to the article.
2. The article of claim 1, wherein the aramid fibers comprise a major amount by weight of the wet-laid, non-woven structure.
3. The article of claim 1, wherein the wet-laid, non-woven structure is comprised of at least 60% by weight aramid fibers.
4. The article of claim 1, wherein the wet-laid, non-woven structure is comprised of at least 70% by weight aramid fibers.
5. The article of claim 1, wherein the wet-laid, non-woven structure is comprised of from about 70 to about 80% by weight aramid fibers. 6. The article of claim 1, wherein the binder is comprised of a second fiber which is heat bondable o the surface of the aramid fibers.
7. The article of claim 6, wherein the second fiber is comprised of a polyester, polypropylene or acrylic fiber. 8. The article of claim 7, wherein the second fiber is comprised of an acrylic fiber.
9. The article of claim 1, wherein the binder is polyvinyl alcohol.
10. The article of claim 1, wherein the binder is heat bonded to the aramid fibers.
11. The article of claim 5, wherein the article is comprised of from about 20 to about 30% by weight acrylic fiber bound to the aramid fiber.
12. The article of claim 1, wherein the wet- laid, non-woven structure is hydroentangled.
13. The article of Claim 1, wherein the article is an article of clothing.
14. The article of claim 13, wherein the article is a vest.
15. The article of claim 13, wherein the article is a glove. 16. The article of claim 13, wherein the article is a jacket.
17. The article of claim 1, wherein the article is a structural panel.
18. The article of claim 1, wherein the article is wall covering.
19. The article of claim 1, wherein the fibers are poly (p-phenylene terephthalamide) aramid fibers and comprise a major amount by weight of the wet- laid, non-woven structure.
20. The article of claim 19, wherein the wet- laid, non-woven structure is comprised of at least
60% by weight of said aramid fibers.
21. The article of claim 19, wherein the wet- laid, non-woven structure is comprised of at least 70% by weight of said aramid fibers.
22. The article of claim 19, wherein the wet- laid, non-woven structure is comprised of from about 70 to about 80% by weight of said aramid fibers.
23. The article of claim 19, wherein the binder is comprised of a second fiber which is heat bondable to the surface of the said aramid fibers. 24. The article of claim 23, wherein the second fiber is comprised of a polyester, polypropylene or acrylic fiber.
25. The article of claim 24, wherein the second fiber is comprised of an acrylic fiber.
26. The article of claim 19, wherein the binder is polyvinyl alcohol.
27. The article of claim 19, wherein the binder is heat bonded to said aramid fibers.
28. The article of claim 22, wherein the article is comprised of from about 20 to about 30% by weight acrylic fiber bound to said aramid fiber.
29. The article of claim 19, wherein the article is an article of clothing.
30. The article of claim 29, wherein the article is a vest.
31. The article of claim 29, wherein the article is a glove.
32. The article of claim 29, wherein the article is a jacket. 33. The article of claim 19, wherein the
article is a structural panel.
34. The article of claim 19, wherein the
article is wallcovering.
35. A multi-layer penetration resistant article which contains at least one layer comprised of a wet-laid, non-woven structure comprised of high strength, high- melting fibers and a binder which binds said fibers, with the high strength, high melting fibers having a tenacity of at least 15 grams/denier, an energy to break of at least 18 Joules/gram and a melting point of at least 200°C, and with the binding of the fibers in the wet-laid, non-woven structure and the basis weight of the wet-laid, non-woven structure being sufficient to allow the fibers to have a tendency to pull out of the structure rather than break in order to permit energy absorption by the fibers and impart penetration resistance to the article.
36. The article of claim 35, wherein the high strength, high melting fibers are
polybenzobisthiazole fibers, polybenzoxazole fibers, liquid crystalline polyester fiber or extended-chain polyvinyl alcohol fibers.
37. A wet-laid, non-woven structure which is comprised of aramid fibers and a binder which binds the aramid fibers, with the binding of the aramid fibers and the basis weight of the wet-laid, non-woven structure being sufficient to allow the fibers to have a tendency to pull out of the structure rather than break in order to permit energy
absorption by the fibers and impart penetration resistance to the structure.
38. The structure of claim 37, wherein the aramid fibers comprise a major amount by weight of the wet-laid, non-woven structure.
39. The structure of claim 37, wherein the structure is comprised of at least 60% by weight aramid fibers.
40. The structure of claim 37, wherein the structure is comprised of at least 70% by weight aramid fibers.
41. The structure of claim 37, wherein the structure is comprised of from about 70% to about 80% by weight aramid fibers. 42. The structure of claim 37, wherein the binder is comprised of a second fiber which is heat bondable to the surface of the aramid fibers.
43. The structure of claim 42, wherein the second fiber is comprised of a polyester,
polypropylene or acrylic fiber.
44. The structure of claim 43, wherein the second fiber is comprised of an acrylic fiber.
45. The structure of claim 37, wherein the binder is polyvinyl alcohol.
46. The structure of claim 37, wherein the binder is heat bonded to the aramid fibers.
47. The structure of claim 37, wherein the structure is hydroentangled. 48. The structure of claim 41, wherein the structure is comprised of from about 20% to about 30% by weight acrylic fiber with the acrylic fiber and aramid fiber being heat bonded. 49. The structure of claim 37, wherein the fibers are poly (p-phenylene terephthalamide) aramid fibers and comprise a major amount by weight of the wet-laid, non-woven structure.
50. The structure of claim 49, wherein the structure is comprised of at least 60% by weight of said aramid fibers. 51. The structure of claim 49, wherein the structure is comprised of at least 70% by weight aramid fibers.
52. The structure of claim 49, wherein the structure is comprised of from about 70% to about 80% by weight of said aramid fibers.
53. The structure of claim 49, wherein the binder is comprised of a second fiber which is heat bondable to the surface of said aramid fibers.
54. The structure of claim 53, wherein the second fiber is comprised of a polyester,
polypropylene or acrylic fiber.
55. The structure of claim 54, wherein the second fiber is comprised of an acrylic fiber.
56. The structure of claim 49, wherein the binder is polyvinyl alcohol.
57. The structure of claim 49, wherein the binder is heat bonded to said aramid fibers. 58. The structure of claim 52, wherein the structure is comprised of from about 20% to about 30% by weight acrylic fiber with the acrylic fiber and said aramid fiber being heat bonded.
59. A wet-laid, non-woven structure which is comprised of high strength, high melting fibers and a binder which binds said fibers, with the high
strength, high melting fibers having a tenacity of at least 15 grams/denier, an energy to break of at least 18 Joules/gram and a melting point of at least 200°C, and with the binding of the fibers and the basis weight of the wet-laid, non-woven structure being sufficient to allow the fibers to have a tendency to pull out of the structure rather than break in order to permit energy absorption by the fibers and impart penetration resistance to the structure.
60. A method for preparing a penetration resistant material comprised of aramid fibers, which comprises creating an aqueous slurry of aramid fibers and a binder for the aramid fibers and passing said slurry onto a wire screen to form a sheet, dewatering the sheet and effecting a binding of the aramid fiber s with the binder, with the degree of binding and the amount of aramid fibers used being such that the basis weight of the sheet and said binding are
sufficient to impart penetration resistance to the material.
61. The method of claim 60, wherein the binder is comprised of a second fiber which is heat bondable to the surface of the aramid fibers, and the step of effecting a binding of the aramid fibers with the binder comprises heat bonding.
62. The method of claim 61, wherein the second fiber is comprised of a polyester, polypropylene or acrylic fiber.
63. The method of claim 62, wherein the second fiber is comprised of an acrylic fiber.
64. The method of claim 60, wherein the binder is polyvinyl alcohol.
65. The method of claim 60, wherein the material is further hydroentangled. 66. The method of claim 61, wherein the
material is further hydroentangled.
67. The method of claim 60, wherein foam is used in creating the aqueous slurry.
68. The method of claim 60, wherein the aramid fibers are fibers of poly (p-phenylene
terephthalamide). 69. A method for preparing a penetration resistant material comprised of high strength, high melting fibers, with the high strength, high melting fibers having a tenacity of at least 15 grams/denier, an energy to break of at least 18 Joules/gram and a melting point of at least 200°C, which comprises creating an aqueous slurry of said fibers and a binde r for said fibers and passing said slurry onto a wire screen to form a sheet, dewatering the sheet and effecting a binding of the fibers with the binder, with the degree of binding and the amount of fibers used being such that the basis weight of the sheet and said binding are sufficient to allow the fibers to have a tendency to pull out of the structure rather than break in order to permit energy absorption by the fibers and impart penetration resistance to the material.
70. The method of claim 69, wherein the binder is comprised of a second fiber which is heat bondable to the surface of said fibers, and the step of effecting a binding of said fibers with the binder comprises heat bonding. 71. The method of claim 70, wherein the second fiber is comprised of a polyester, polypropylene or acrylic fiber.
72. The method of claim 71, wherein the second fiber is comprised of an acrylic fiber.
73. The method of claim 70, wherein the binder is polyvinyl alcohol. 74. The method of claim 69, wherein foam is used in creating the aqueous slurry.
STATEMENT UNDER ARTICLE 19
For example, the Klein reference (U.S. Patent No.
4,716,062) discloses a high strength light weight composite material comprising discrete reinforcing elements surrounded by a matrix including polymer microbits. Thus, even though the patent does disclose the use of Kevlar® fibers, the patent does not in any manner suggest the present invention wherein the fibers are bound such that the fibers have a tendency to actually pull out of the structure rather than break when met by a projectile. Rather, the reference discloses the creation of a composite hardboard, wherein the fibers are embedded in microbits of a densified matrix. No movement whatsoever would be possible for the fibers in such a matrix, and hence they would simply tend to shatter or break rather than pull out of the structure.
The Tracy patent (U.S. Patent No. 4,199,388) noted discloses a method for making a multi-plied continuous
filament ballistic helmet. The helmet is made from layers of resin coated bundles of plural, continuous filaments. The helmet is not made by a papermaking process, e.g., it is not a non-woven wet laid article. Furthermore, the continuous filaments do not have the freedom of movement to be pulled out of the structure, which is the mechanism relied upon in the articles and structures of the claimed invention.
The Trask reference (U.S. Patent No. 4,726,987) cited in the International Search Report does not relate to a wet laid non-woven structure, and does not discuss any particular penetration resistance to be exhibited by the structural panel created. Rather, fire retardence is the main advantage of the structural textile panel disclosed in the Trask reference.
The reference in no manner discloses the claimed invention.
The last document cited is that of Stanislawczyk (U.S. Patent No. 4,929,495. This patent relates to a nonwoven fabric coated with carboxylated acrylate polymers. In no manner does it disclose the penetration resistant articles of the claimed invention.
Accordingly, it is respectfully submitted that the subject application does meet all requirements for
patentability, and a favorable opinion is therefore
respectfully requested.
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