JP2008525243A - Moisture-resistant PBO fiber, article thereof and method for producing the same - Google Patents

Abstract

PBO fiber, PBO fiber-containing sheet having improved physical properties after exposure to high humidity, and aggregates thereof. PBO fiber sealed with a water vapor transmission rate of less than 25 × 10 ⁻¹¹ cm ³ (stp) cm / (cm ² · sec · Pa) as measured by ASTM E96-95 (Procedure E) at 37.8 ° C. It is encapsulated in the agent by anhydrous means. In the case of a PBO fiber-containing sheet, the sealant partially fills the volume between the fibers.

Description

  The present invention relates to PBO fibers having improved retention of physical properties after exposure to high humidity, fiber sheets containing PBO fibers, and aggregates thereof. These fibers, sheets and articles have found utility in applications requiring shock absorption, ballistic resistance and penetration resistance, as well as other applications.

  The production of high strength fibers from materials such as aramid, high molecular weight polyethylene (HMWPE), and more recently polybenzazole (PBO) has made it possible and practical to meet a wide range of needs. Perhaps most dramatically, personal protective clothing made from these fibers has saved the lives of many police and military personnel.

  Body protection garments are usually formed from multiple layers of woven fabric, or a nonwoven sheet consisting of fibers twisted together. The fibers in the nonwoven sheet can be oriented in one direction or felted in an irregular orientation. Unidirectional fiber sheets (UD sheets) generally include a matrix resin that fills the volume between the fibers. The continuous UD sheets are angled relative to each other, for example 0 ° / 90 ° or 0 ° / 45 ° / 90 ° / 45 ° / 0 ° or other angles. Cross-plied UD sheets generally have better ballistic resistance than fabrics and therefore have weight advantages. Rigid ballistic composites useful for applications such as mob suppression shields and helicopter sheets, individual sheets are bonded together using heat and pressure, and the matrix in each sheet is bonded and bonded between them And establishes the whole into one unified article.

  For high strength fibers currently on the market, PBO fibers have very high strength and tensile modulus, both of which are important for propagating and spreading distorted waves involved in ballistic events. Unfortunately, however, PBO fibers can be weakened by exposure to high humidity (gas phase moisture), resulting in degradation of their ballistic effectiveness. According to a publication titled “PBO Fiber ZYLON®” technical information (revised September 2001) by Toyobo Co. LTD., PBO fiber is It can be seen that about 26% of the strength is lost after 6 weeks of accelerated aging at 80% relative humidity. It is often desirable for body armor to have sufficient "breathability", i.e., water vapor permeability, to increase comfort for clothing. Thus, manufacturing a body suit from PBO may need to overcome two conflicting challenges. That is, to protect the PBO fibers from the effects of humidity and at the same time to provide water vapor permeability through the protective clothing for comfort of clothing.

  Ballistic and / or penetration-resistant articles, including PBO fabrics, are known in the prior art. For example, US Pat. No. 6,559,079, US Pat. No. 6,449,769, US Pat. No. 6,238,768 and US Pat. No. 5,552,221 See

  These prior art, alone or in combination, do not describe the specific configuration of the article or method of the present invention and cannot satisfy all the requirements achieved by the present invention.

  The present invention is a method of forming PBO fibers and PBO fiber-containing sheets, and aggregates thereof, having improved retention of physical properties after exposure to high humidity and high temperature. These fibers, sheets and aggregates have found utility in applications requiring impact absorption, ballistic resistance and penetration resistance, as well as other applications.

  In one embodiment, the present invention is a method of forming PBO fibers that are resistant to the effects of heat and moisture, including the step of encapsulating the PBO fibers in a sealant by anhydrous means.

The sealant has a water vapor transmission rate of less than 25 × 10 ⁻¹¹ cm ³ (stp) · cm / (cm ² · sec · Pa) as measured by ASTM E96-95 (Procedure E) at 37.8 ° C. . The fiber can be formed into a variety of other articles.

In another embodiment, the present invention is a method of forming a sheet comprising PBO fibers and resistant to the effects of heat and moisture comprising:
a) forming a fibrous sheet containing a plurality of PBO fibers in a fibrous network;
by b) means Anhydrous PBO fibers in a sealant comprising the steps of: encapsulating, sealing agent is measured at 37.8 ° C. by ASTM E96-95 (Procedure E) 25 × 10 -11 cm ³ (stp) · cm / (cm ² · sec · Pa), a water vapor transmission rate of less than ³ (stp) · cm / (cm ² · sec · Pa), and the sealing agent partially fills the volume between the fibers, Further comprising bonding the fibers together;
c) optionally, adhering a plastic film to at least one side of the fibrous sheet.

In yet another embodiment, the present invention provides a ballistic that retains at least 87% of the initial V50 value for a Geco 9 mm, 124 grain, FMJ (steel jacket) bullet after 4 weeks of accelerated aging testing at 70 ° C. and 80% relative humidity. A method for forming a seximetric article, comprising:
a) forming a fibrous sheet comprising a plurality of PBO fibers in a fibrous network;
by b) means Anhydrous PBO fibers in a sealant comprising the steps of: encapsulating, sealing agent is measured at 37.8 ° C. by ASTM E96-95 (Procedure E) 25 × 10 -11 cm ³ (stp) · cm / (cm ² · sec · Pa), a water vapor transmission rate of less than ³ (stp) · cm / (cm ² · sec · Pa), and the sealing agent partially fills the volume between the fibers, Further comprising bonding the fibers together;
c) optionally bonding a plastic film to at least one side of the fibrous sheet;
d) stacking a plurality of fibrous sheets in an unbonded or lightly bonded array.

In another embodiment, the present invention provides a ballistic resistance that retains at least 87% of the initial V50 value for a Geco 9 mm, 124 grain, FMJ (steel jacket) bullet after a 4 week accelerated aging test at 70 ° C. and 80% relative humidity. A method of forming an article comprising:
a) arranging a plurality of PBO fibers in a unidirectional, planar sheet;
b) encapsulating PBO fibers in a sealant by anhydrous means, the sealant being 25 × 10 ⁻¹¹ cm as measured by ASTM E96-95 (Procedure E) at 37.8 ° C. Having a water vapor transmission rate of less than ³ (stp) · cm / (cm ² · sec · Pa), the sealant partially fills the volume between the fibers and binds the fibers together Forming a coherent sheet;
c) stacking the first and second sheets of cohesive sheets together, wherein the direction of the fibers in the first sheet is at least 30 ° to the direction of the fibers in the second sheet. Steps
d) bonding the first and second cohesive sheets together to form a laminate;
e) optionally, adhering a plastic film to at least one side of the laminate;
f) stacking a plurality of said laminates on each other in an unbonded or lightly bonded arrangement.

  In another embodiment, the invention includes the PBO fiber, a fibrous sheet, and an article comprising one or more fibrous sheets that include PBO fibers in a fiber network. In each of these, the PBO fibers are encapsulated in the sealant as described above. Fibrous sheets can be formed from encapsulated PBO fibers or can be formed from PBO fibers and then encapsulated. In the latter fibrous sheet that is subsequently encapsulated, the sealant partially fills the volume between the fibers, and in the case of a nonwoven sheet, the sealant further binds the fibers. The present invention also includes a collection of these articles.

In one embodiment, the present invention is a method of forming PBO fibers that are resistant to the effects of heat and moisture, comprising encapsulating the PBO fibers in a sealant by anhydrous means. . This sealant has a water vapor transmission rate of less than 25 × 10 ⁻¹¹ cm ³ (stp) · cm / (cm ² · sec · Pa) measured at 37.8 ° C. by ASTM E96-95 (Procedure E). Have.

In another embodiment, the present invention is a method of forming a sheet comprising PBO fibers that is resistant to the effects of heat and moisture, comprising:
a) forming a fibrous sheet containing PBO fibers in the fiber network;
b) encapsulating PBO fibers in a sealant by anhydrous means, the sealant being 25 × 10 ⁻¹¹ cm as measured by ASTM E96-95 (Procedure E) at 37.8 ° C. Having a water vapor transmission rate of less than ³ (stp) · cm / (cm ² · sec · Pa);
c) partially filling the volume between the fibers with the sealant;
d) optionally bonding a plastic film to at least one side of the fibrous sheet.

In yet another embodiment, the present invention provides a ballistic that retains at least 87% of the initial V50 value for a Geco 9 mm, 124 grain, FMJ (steel jacket) bullet after 4 weeks of accelerated aging testing at 70 ° C. and 80% relative humidity. A method for forming a seximetric article, comprising:
a) forming a fibrous sheet containing PBO fibers in the fiber network;
b) encapsulating the PBO fibers in a sealant by anhydrous means, the sealant being 25 × 10 ^{−11 as} measured by ASTM E96-95 (Procedure E) at 37.8 ° C. having a water vapor transmission rate of less than cm ³ (stp) · cm / (cm ² · sec · Pa), the sealant partially filling the volume between the fibers, In some cases, further bonding the fibers;
c) optionally bonding a plastic film to at least one side of the fibrous sheet;
d) stacking a plurality of the fibrous sheets on each other in an unbonded or lightly bonded array.

In another embodiment, the present invention provides a ballistic resistance that retains at least 87% of the initial V50 value for a Geco 9 mm, 124 grain, FMJ (steel jacket) bullet after a 4 week accelerated aging test at 70 ° C. and 80% relative humidity. A method of forming an article comprising:
a) arranging a plurality of PBO fibers on a unidirectional, planar sheet,
b) encapsulating the PBO fibers in a sealant by anhydrous means, the sealant being 25 × 10 ^{−11 as} measured by ASTM E96-95 (Procedure E) at 37.8 ° C. having a water vapor transmission rate of less than cm ³ (stp) · cm / (cm ² · sec · Pa), the sealant partially fills the volume between the fibers and binds the fibers Forming a coherent sheet;
c) stacking the first and second sheets of the cohesive sheet together, wherein the direction of the fibers in the first sheet is at least 30 ° to the direction of the fibers in the second sheet And the steps that comprise
d) bonding the first and second cohesive sheets together to form a laminate;
e) optionally, adhering a plastic film to at least one side of the laminate;
f) stacking a plurality of said laminates on each other in an unbonded or lightly bonded arrangement.

  In other embodiments, the present invention includes the fibers, fibrous sheets, and articles comprising one or more fibrous sheets that include PBO fibers in a fibrous network. The fibers and / or the fibrous sheet are encapsulated in the above-described sealant. In the case of a fibrous sheet, the sealant partially fills the volume between the fibers, and in the case of a nonwoven sheet, further bonds the fibers. The present invention also includes a collection of these articles.

  For the purposes of the present invention, fibers are elongated objects whose longitudinal dimensions are much longer than the width and thickness in the direction perpendicular to the length. Accordingly, “fiber” as used herein includes one or more filaments, ribbons, strips, and the like having a regular or irregular cross-section in continuous or discontinuous length. A yarn is a collection of continuous or discontinuous fibers. As used herein, a “fiber network” or “network” is a plurality of fibers arranged in a predetermined configuration, or twisted or twisted arranged in a predetermined configuration. Means a plurality of fibers grouped together to form no yarn. The fiber network can have a variety of configurations. For example, the fibers or yarns may be configured as felt, knitted fabric, netting, woven fabric, irregularly oriented planar nonwoven fabric, unidirectionally oriented nonwoven fabric, or formed into a network by any conventional technique. obtain. According to a particularly preferred network arrangement, the fibers are aligned in one direction so as to be substantially parallel to one another along the length of the network layer.

  Sheets and articles of the present invention may further comprise other high strength fibers such as high molecular weight polyethylene (HMPE), aramid, and liquid crystalline polyester. When used with PBO fibers in a unidirectional fiber orientation, these fibers are preferably aligned parallel to the PBO fibers. It is also preferred that the fibers of different compositions are arranged in a periodical arrangement, in a direction perpendicular to the direction of the fibers. The hybrid fiber-containing sheet article of the present invention preferably contains 10 to 100% PBO fiber based on the total fiber weight.

  In the context of the present invention, PBO fibers are polybenzazole fibers or polybenzoxazole fibers. Suitable PBO fibers for practicing the present invention include, for example, US Pat. No. 5,185,296, US Pat. No. 5,286,833, US Pat. No. 5,356,584, US No. 5,534,205, U.S. Pat. No. 5,976,447 and U.S. Pat. No. 6,040,050, which are incorporated herein by reference. The Preferably, the PBO fiber is ZYLON® brand poly (p-phenylene-2,6-benzobisoxazole) commercially available from Toyobo Co., Ltd.

  HMWPE fibers useful in the present invention have an intrinsic viscosity in decalin of from about 5 deciliters per gram (dl / g) to about 35 dl / g at 135 ° C. Such high molecular weight polyethylene fibers are commercially available from Honeywell International Inc. under the trade name SPECTRA®. The disclosure of U.S. Pat. No. 4,413,110 is hereby incorporated by reference to the extent that it does not conflict with the description herein. HMWPE fibers can also be produced by rolling and drawing processes such as those described in US Pat. No. 5,702,657 and are available from ITS Industries Inc. (TENSYLON) (registered). Trade name).

  Aramid fibers useful in the present invention are described in U.S. Pat. No. 3,671,542 and are available from EI Dupont Co. KEVLAR (R) and Nomex. (NOMEX) (registered trademark), Teijin Twaron BV to TWARON (registered trademark), TECHNORA (registered trademark), and Teijin Connex (registered trademark), JSC Him Volokno (JSC) It is commercially available from Chim Volokno under the trade name ARMOS, and Kamensk Volokno JSC under the trade names Rusar and SVM. Poly (p-phenylene terephthalamide) fibers and p-phenylene terephthalamide aramid copolymer fibers having reasonably high modulus and toughness values are particularly useful in the present invention. An example of a p-phenylene terephthalamide copolymer aramid useful in the present invention is co-poly- (paraphenylene 3,4'-oxydiphenylene terephthalamide). Also useful in the practice of the present invention is poly (m-phenylene isophthalamide) fiber.

  Liquid crystal copolyester fibers suitable for the practice of the present invention are described, for example, in US Pat. No. 3,975,487, US Pat. No. 4,118,372 and US Pat. No. 4,161,470. It is disclosed.

  Examples of anhydrous means for encapsulating PBO fibers in the sealant include chemical vapor deposition, gas phase polymerization and vapor deposition, drying after in situ polymerization in an aqueous solution, and an anhydrous sealant solution. Other means that do not include drying after coating and contacting the fibers with an aqueous medium such as a solution or dispersion. U.S. Pat. No. 4,624,867, U.S. Pat. No. 5,447,799, and U.S. Pat. No. 6,179,922 which describe means for vapor deposition of polymers onto a substrate. The disclosure of U.S. Patent Application Publication No. 2002 / 0002219A1, which describes the disclosure and means of in situ polymerization of fluoropolymer in a porous substrate, is incorporated herein by reference to the extent not inconsistent with this specification. Is done. A preferred means of encapsulating the PBO fibers is to coat the PBO fibers with an aqueous solution of sealant and subsequently dry.

  The preferred method of the present invention is schematically illustrated in FIG. 1 as a unidirectional fiber network. What changes are made to the apparatus described to accommodate woven, knitted, braided, irregularly oriented planar (eg, placed by airflow) or felted networks It should be clear to those skilled in the art what to do.

  PBO fibers are fed from the creel 102 and form a unidirectional network through the bonding station 104. The fiber network then extends around the fixation bar 20 to expand the yarn into a thin layer. The fiber network is then immersed in a non-aqueous bath 105 of sealant and carried under the roll to completely coat each and all filaments. The concentration of the sealant in the anhydrous solvent prevents the sealant from completely filling the volume between the filaments when the solvent is dried. The concentration of the sealant is selected in relation to the water vapor permeability of the sealant. The lower the water vapor permeability of the sealant, the lower the sealant solution concentration can be. When dealing with non-woven fiber networks such as unidirectional fibers, the encapsulant concentration also has the limitation that it must be sufficient to bind the fibers in a coherent sheet for structural integration. receive. Preferably, the concentration of sealant in the coating solution is from 1% to 25% (1% to 25% by weight) of the solution by weight, more preferably from 5% to 20% by weight. The squeeze roll 106 at the bath exit removes excess sealant from the fiber network.

  The coated fiber network is combined with a carrier network 107, which can be paper, plastic film or fabric. The coated fiber network is then passed through a heating oven 112 to evaporate the solvent in the sealant, thereby encapsulating the fibers in the sealant. The sealant partially fills the volume between the fibers and binds the fibers to form a coherent sheet. Nip rollers 116 are used to pull the carrier network and fiber sheet through the system. The substrate and fiber sheet are wound on a roller 118 for subsequent manufacture of the laminate or composite of the present invention. The carrier net may be peeled from the fiber sheet or may be part of the final laminate or composite.

The sealant functions as a moisture-proof layer, protects the PBO fiber, and also functions as a binder and can provide a bond to the nonwoven fabric fiber sheet. The sealant is less than 25 × 10 ⁻¹¹ cm ³ (stp) · cm / (cm ² · sec · Pa) as measured by ASTM standard test method E96-95 (Procedure E) at 37.8 ° C., more preferably Has a water vapor transmission rate of less than 5 × 10 ⁻¹¹ cm ³ (stp) · cm / (cm ² · sec · Pa). The abbreviation “stp” in transmittance units has the commonly understood meaning of “standard temperature and pressure”.

The type of sealant is selected according to the end use requirements for an article made from the sheet of the present invention. Where flexible articles are required, the sealant is preferably an elastomer with an initial tensile modulus of less than 6,000 psi (41.4 MPa) as measured by ASTM D638. If a hard article is required, the stiffness can be obtained by adding a sufficient number of sheets with a low stiffness sealant or less sheets with a high stiffness resin sealant. Can be obtained. Where the article is a laminate used for structural composites, the sealant preferably has an initial tensile modulus of 1 × 10 ⁶ psi (6.9 GPa) as measured by ASTM D638.

  A variety of elastomeric materials and formulations with suitably low water vapor transmission rates and elastic modulus can be utilized as sealants in the present invention. For example, suitable materials include polyisoprene, natural rubber, ethylene-propylene copolymer, ethylene-propylene-diene terpolymer, polychloroprene (Neoprene G), poly (isobutylene-co-isoprene) (butyl rubber), styrene-isoprene-styrene. Block copolymers (KRATON® D1107 brand), styrene- (ethylene-co-butylene) -styrene block copolymers [KRATON® G1650 brand], and polytrichlorofluoroethylene. Some water vapor transmission rates of these elastomers are described, for example, in “Polymer Handbook” 2nd edition, J. MoI. Brand Wrap and J. Bradrup H. E. H. Immergut, pp. III-229-III-250, John Willy & Sons, New York, 1975 and (1965), and “Fact Sheet K0102 Gas Permeability of KRATON Polymers ", Kraton Polymers Inc. and is shown in Table I.

  Examples of the high elastic modulus sealant resin that may be useful for the laminate of the present invention include thermosetting allyls, aminos, cyanates, epoxies, phenols, unsaturated polyesters, bismaleimides, and rigid polyurethanes. , Silicones, vinyl esters and copolymers thereof and mixtures thereof. A thermosetting vinyl resin is preferred.

  The vinyl ester is preferably produced by esterifying a polyfunctional epoxy resin with an unsaturated monocarboxylic acid, usually methacrylic acid or acrylic acid. Examples of vinyl esters include diglycidyl adipate, diglycidyl isophthalate, di- (2,3-epoxybutyl) adipate, di- (2,3-epoxybutyl) oxalate, di- (2,3 succinate) -Epoxyhexyl), di- (3,4-epoxybutyl) maleate, di (2,3-epoxyoctyl) pimelate, di- (2,3-epoxybutyl) phthalate, di- (2) tetrahydrophthalate , 3-epoxyoctyl), di- (4,5-epoxydodecyl maleate), di- (2,3-epoxybutyl) terephthalate, di- (2,3-epoxyphenyl) thiodipropionate, diphenyldicarboxylic Acid di- (5,6-epoxytetradecyl), sulfonyldibutyric acid di- (3,4-epoxyheptyl), 1,2,4-butanetricarboxylic acid Li- (2,3-epoxybutyl), di- (5,6-epoxypentadecyl) maleate, di- (2,3-epoxybutyl) azelate, di- (3,4-epoxypentadecyl citrate) ), Cyclohexane-1,3-dicarboxylate di- (4,5-epoxyoctyl), di- (4,5-epoxyoctadecyl) malonate, bisphenol-A-fumaric acid polyester and similar materials. Most preferred are epoxy-based vinyl ester resins such as DERAKANE® from Dow Chemical Company.

  An anhydrous solvent is chosen to be a good solvent for the sealant. An anhydrous solvent in the context of the present invention is one that contains less than 0.5% by weight of water. The anhydrous solvent preferably contains less than 0.1% water by weight. Most preferably, the anhydrous solvent contains less than 0.01% by weight of water. Solvents for some polymers useful as sealants are described in, for example, “Polymer Handbook” 2nd edition, J. MoI. Brand Wrap and J. Brandrup H. Edited by E. H. Immergut, pages IV-241 to IV-262, John Wiley & Sons, New York, 1975, incorporated herein by reference. Is done. The anhydrous solvent preferably has a boiling point of less than 150 ° C. and more preferably less than 100 ° C. under normal pressure in order to evaporate easily. A preferred anhydrous solvent for the hydrocarbon elastomer sealant is cyclohexane. A preferred anhydrous solvent for the epoxy-based vinyl ester resin is methyl ethyl ketone.

The present invention is also a fibrous sheet comprising PBO fibers in a fiber network, the fibers measured at 37.8 ° C. according to ASTM E96-95 (Procedure E) at 25 × 10 ⁻¹¹ cm ³ (stp ) · Cm / (cm ² · sec · Pa) encapsulated in a sealant having a water vapor transmission rate of less than 5 and 99% of the volume between fibers, preferably 15 Fill ~ 95%. It is also preferred that the sealant is deposited from an aqueous solution and subsequently dried. The sealing agent is preferably 1% to 50% by weight of the fibrous sheet, more preferably 5% to 25% by weight, and most preferably 5% to 20% by weight. In some cases, a plastic film is adhered to one or both sides of the fibrous sheet.

  One article of the invention is a plurality of fibrous sheets of the invention in a stacked arrangement. In a preferred embodiment, the fibers constituting the fibrous sheet are oriented in one direction parallel to each other, and the fiber direction of one sheet forms an angle with the fiber direction of an adjacent sheet. The fibrous sheets may not be bonded to each other, may be lightly bonded, or may be bonded together. Preferred articles of the invention include unidirectional fibrous sheets that are crossed together and bonded together. Crossing together is hereby incorporated herein by reference to the extent it does not conflict with the present specification, US Pat. No. 5,173,138 or US Pat. No. 5,766,725. Can be performed by a continuous crossover operation as described in the document, or by hand layup, or other suitable means.

  In a preferred embodiment, the present invention comprises a laminate comprising first and second unidirectional fibrous sheets of the present invention bonded together in a stacked arrangement, wherein the fiber orientation in the first sheet is And an angle of at least 30 ° to the fiber direction in the second sheet. Preferred articles of the invention include a plurality of these laminates in a stacked arrangement that are not bonded together or are lightly bonded.

  In another embodiment, the laminate of the present invention comprises one or more inventive sheets sandwiched between one or more fibrous sheets of other high strength fibers bonded together in a stacked arrangement. It has a plastic film comprising a fibrous sheet of PBO and optionally adhered to one or both sides of the laminate. The preferred form of this embodiment is, in order, first, second, third and fourth sheets; the first and fourth thin layers comprise aramid fibers, the second and third thin layers comprise PBO fibers, The sheet then includes laminates that are bonded together in a stacked arrangement. Most preferably, each fibrous sheet comprises unidirectional fibers in which the fiber directions in adjacent sheets are perpendicular to each other.

In some cases, a plastic film may be adhered to one or both sides of the article of the present invention. Preferably, the plastic film is selected from members selected from the group consisting of polyolefin, polyamide, polyester, polycarbonate, ionomer, cellulose, cellulose ester, ethyl cellulose, polyfluorocarbon. When a plastic film is present, it preferably constitutes 1% to 40% by weight of the article. The plastic film preferably has a water vapor transmission of 5 × 10 ⁻⁹ cm ³ (stp) / (cm · sec · Pa) or more as measured by ASTM E96-95 (Procedure E) at 37.8 ° C. More preferably, it is at least 10 ⁻⁹ cm ³ (stp) / (cm · sec · Pa). Since transmission corresponds to the transmission divided by the film thickness, a thinner film should use a material with lower transmission, and vice versa. For example, in the case of a polyethylene film with a density of 0.914 having a transmittance of 0.675 × 10 ⁻¹¹ cm ³ (stp) cm / (cm ² · sec · Pa), the film thickness is 0.0005 inch (0.003 inch). Preferably less than or equal to 0014 cm). Most preferably, the plastic film is a porous film.

  In order to form the laminate of the present invention by bonding the unidirectional PBO fiber sheet of the present invention, it is preferable to apply heat and pressure. Depending on the type of sealant and the plastic film present, temperatures of about 90 ° C. to about 160 ° C. and pressures of about 100 psi to about 2,500 psi (69 to 17,000 kPa) are used.

  In another embodiment, the present invention is an article comprising a plurality of the above laminates of the present invention in a stacked arrangement, wherein the laminates are not bonded to each other or are lightly bonded, ie these Only joined at the edges or corners. It will be appreciated that the number of laminates making up the article and their dimensions are determined by the nature of the application.

The article is preferably penetration resistant and / or ballistic resistant. The penetration-resistant article of the present invention preferably meets at least the requirements of NIJ standard 0115.00 for Type 1 piercing protection. The ballistic resistant article of the present invention preferably meets at least the requirements of NIJ Standard 0101.04 Revision A for Type IIa body armor. The ballistic article of the present invention has a specific energy absorption of at least 300 J-m ² / Kg and a V50 value of at least 1,300 ft / sec (396 m / sec) when impacted by a 9 mm Geco, 124 grain FMJ (steel jacket) bullet. Is more preferable. The V50 value refers to that velocity with a 50% probability that the bullet will penetrate the article. Even more preferably, the ballistic article of the present invention retains at least 87% of the initial V50 value after an accelerated aging test of 4 weeks at 70 ° C. and 80% relative humidity. Most preferably, the ballistic article of the present invention retains at least 85% of the initial V50 value after a 6 week accelerated aging test at 70 ° C. and 80% relative humidity.

  In another embodiment, the present invention is a composite comprising a plurality of unidirectional fiber sheets of the present invention bonded together in a stacked arrangement, wherein the fiber direction of one sheet is An angle is formed with respect to the fiber direction of the adjacent sheet.

  The following examples are presented for a more complete understanding of the invention. The specific techniques, conditions, materials, ratios and reporting data set forth to illustrate the principles of the invention are exemplary and should not be construed as limiting the scope of the invention.

Comparative Example 1
A unidirectional fiber sheet of PBO was prepared using the apparatus schematically shown in FIG. Several rolls of 1,005 denier PBO fibers (ZYLON (registered trademark) AS brand, manufactured by Toyobo Co., Ltd.) are fed from the creel 102 and passed through the bonding station 104 to form a unidirectional network Formed. This fibrous network was passed above and below the stationary bar 20 to expand the yarn into a thin layer. The fiber network was then carried under a roll immersed in a bath of an aqueous dispersion of elastomeric styrene-isoprene-styrene block copolymer sealant to fully coat each filament. Prinlin® 7137AL, supplied by Sovereign Specialty Chemicals, Buffalo, NY (Sovereign Specialty Chemicals, Buffalo, NY), contains an aqueous dispersion containing 41-45 wt% solids by the manufacturer “Resin-modified water-based dispersion Kraton® D1107”.

The coated fiber network was passed through squeeze roll 106 to remove excess sealant dispersion at the bath outlet. The coated fiber network was placed on a 0.35 mil (0.00089 cm) polyethylene film carrier network 107, passed through a heating oven to evaporate the water, and added to the sealant to seal 20% by weight of the fiber. A coherent fiber sheet containing the agent was formed. The total area density of the fiber, sealant and plastic film was 48.5 g / m ² . The fiber area density was 36 g / m ² . The area density of the sealing agent in the fiber sheet was 9 g / m ² . The carrier network and fiber sheet were then wound on rollers 118, especially for the production of laminates.

  The two roll sheet material described above was mounted on a cross-to-cross machine described in US Pat. No. 5,173,138. Laminate this sheet material with PBO vs. PBO crossed at 0 ° / 90 °, consolidated at 115 ° C. and 500 psi (3.5 MPa) pressure, two identical thin layers of PBO fibers and a polyethylene film on both sides Was made.

  The laminate was cut into a number of pieces having a lateral dimension of 40 cm × 40 cm. Twenty-two sheets were stacked and their peripheries were stitched together to form a number of ballistic test articles. One set of articles was placed under standard atmospheric conditions. Other articles were subjected to accelerated aging at 70 ° C. and 80% relative humidity for 4 and 6 weeks. All articles were returned to standard atmospheric conditions for a minimum of 3 days prior to ballistic testing. The results of the ballistic test using 9 mm Geco, 124 grain, FMJ (steel jacket) bullets are shown in Table II below.

Example 1
Instead of an aqueous dispersion, the sealant bath is a styrene-isoprene-styrene block copolymer elastomer in anhydrous cyclohexane having less than 0.1 wt% water [KRATON® D1107, Kraton Polymers. , Inc.)], a unidirectional fiber sheet of PBO was prepared as described in Comparative Example 1. The sealant was a water vapor of 21.5 × 10 ⁻¹¹ cm ³ (stp) · cm / (cm ² · sec · Pa) measured at 37.8 ° C. according to ASTM standard test method E96-95 (Procedure E). It had permeability and had an initial tensile modulus of 200 psi (1.4 MPa) as measured by ASTM D638.

  The coated fiber network is placed on a 0.35 mil (0.00089 cm) polyethylene film carrier 107, passed through a heating oven to evaporate cyclohexane, each filament is encapsulated in a sealant, and between the fibers A coherent fiber sheet was formed whose volume was partially filled with sealant. The cohesive PBO fiber sheet of the present invention contains 20% by weight of the fiber sealant in addition to the sealant. The plastic film carrier and fiber sheet of the present invention were then wound around a roller 118 in preparation for the production of the laminate of the present invention.

The volume portion between the fibers filled with the sealant was measured as follows: In addition to the fibers and sealant, the total area density of the plastic film was 48.5 g / m ² . The fiber area density was 36 g / m ² . The area density of the sealing agent in the fiber sheet was 9 g / m ² . The density of the PBO fiber is 1.54 g / cm ³ . The volume actually occupied by PBO fibers per m ^{2 of the} coated fiber sheet therefore corresponded to 36 g / 1.54 g / cm ³ = 23.4 cm ³ . The sealant, KRATON® D1107, had a density of 0.92 g / cm ³ . The volume of sealant per m ^{2 of the} coated fiber sheet therefore corresponded to 9 g / 0.92 g / cm ³ = 9.8 cm ³ .

When the total thickness of the plastic film in addition to the fiber sheet was measured, it was 0.0043 cm. The thickness of the coated fiber sheet (sealant in addition to the fiber) was the thickness of the plastic film minus the total thickness, corresponding to 0.0043 cm−0.00089 cm = 0.341 cm. The volume of 1 m ² of the coated fiber sheet was therefore 0.00341 cm × 10 ⁴ cm ² = 34.1 cm ³ . The difference in volume of the coated fiber sheet volume and fibers was volume ^{= 34.1cm 3 -23.4cm 3 =} 10.7cm ³ between the fibers. The volume of the sealant was 9.8 cm ³ . Therefore, the sealant accounted for 9.8 / 10.7 × 100 = 92% of the inter-fiber volume of the cohesive PBO fiber sheet of the present invention.

Two rolls of the above inventive sheet material were placed on a cross-matching machine as described in US Pat. No. 5,173,138. This sheet material was crossed together at 0 ° / 90 ° PBO against PBO, consolidated at a temperature of 115 ° C. and a pressure of 500 psi (3.5 MPa), two thin layers of the same PBO fiber and a polyethylene film on both sides A laminate having The polyethylene film has a water vapor transmission rate of 7.5 × 10 ⁻⁹ cm ³ (stp) / (cm · sec · Pa) measured at 37.8 ° C. according to ASTM standard test method E96-95 (Procedure E). did.

  This laminate was cut into multiple pieces having a lateral dimension of 40 cm × 40 cm. A number of articles of the present invention, each consisting of 22 such laminates, were formed by stacking and stitching their peripheries. A set of articles was tested to obtain initial ballistic resistance. Other articles were exposed to accelerated aging at 70 ° C. and 80% relative humidity for 4 and 6 weeks. Prior to the ballistic test, all articles were returned to standard atmospheric conditions for a minimum of 3 days. The results of the ballistic test using 9 mm Geco, 124 grain, FMJ (steel jacket) bullets are shown in Table 2 below.

  Articles of the present invention where the sealant is applied from a solution in an anhydrous solvent may exhibit significantly greater retention of ballistic properties after exposure to high humidity compared to articles where the sealant is applied from an aqueous dispersion. Recognize. The articles of the invention were held at 70 ° C. and 80% relative humidity after 4 weeks for 87% of the initial V50 value and after 6 weeks for over 85%. The “breathability” of the article was imparted by incompletely filling the volume between the fibers and providing a sufficiently permeable surface film.

The article of the present invention exhibited a specific energy absorption greater than 300 J-m ² / Kg for 9 mm Geco 124 grain, FMJ (steel jacket) bullets. The articles of the present invention met at least the requirements of NIJ Standard 0101.04 Revision A for Type IIA body armor.

Example 2
The composite of the present invention is formed from 22 laminates as described in Example 1 consisting of two cross-ply thin PBO fiber layers and polyethylene films on both sides. The laminate is molded and bonded at a temperature of 115 ° C. and a pressure of 1,000 psi (6.9 MPa). The composite meets the requirements of NIJ Standard 0101.04 Revision A for Type IIA personal protective clothing and the requirements of NIJ Standard 0115.00 for Type I piercing protection and has an initial V50 after 4 weeks at 70 ° C. and 80% relative humidity. Hold above 87% of value.

Example 3
A poly (isobutylene) elastomer in anhydrous cyclohexane containing less than 0.1% water by weight (VISTANEX® PIBMM I-100, ExxonMobil Chemical Co.). Manufacture] A unidirectional fiber sheet of PBO is prepared as described in Example 1 except that it is a 10 wt% solution. The sealant was a water vapor of 0.28 × 10 ⁻¹¹ cm ³ (stp) · cm / (cm ² · sec · Pa) measured at 37.8 ° C. by ASTM standard test method E96-95 (Procedure E). Permeability, and initial tensile modulus less than 6,000 psi (41.3 MPa) as measured by ASTM D638.

Porous having a water vapor transmission rate of 50 × 10 ⁻⁹ cm ³ (stp) / (cm · sec · Pa) as measured by ASTM E96-95 (Procedure E) at 37.8 ° C. The polytetrafluoroethylene film carrier network 107 is placed. The coated fiber network and film carrier are passed through a heating oven to evaporate the cyclohexane and form a coherent fiber sheet in which each filament is encapsulated in a sealant. The cohesive PBO fiber sheet of the present invention contains 10% by weight of the fiber sealant in addition to the sealant. This sealant occupies 51% of the volume between the fibers. The plastic film carrier network and fiber sheet of the present invention were then wound around rollers 118 in preparation for the production of the laminate of the present invention.

  Two rolls of the above inventive sheet material were placed on a cross-matching machine as described in US Pat. No. 5,173,138. This sheet material is PBO against PBO, crossed at 0 ° / 90 °, consolidated at a temperature of 115 ° C. under a pressure of 500 psi (3.5 MPa), two identical PBO fiber thin layers and a porous plastic film on both sides A laminate having

  The laminate was cut into a number of pieces having a lateral dimension of 40 cm × 40 cm. A number of articles of the present invention, each consisting of 22 such laminates, were formed by stacking and stitching their peripheries. The article of the present invention thus formed meets at least the requirements of NIJ Standard 0101.04 Revision A for Type IIA personal protective clothing and achieves 87% of the initial V50 value after 4 weeks exposure at 70 ° C. and 80% relative humidity. Held at least.

Example 4
A unidirectional fiber sheet of PBO was prepared as described in Example 1 except that the polyethylene film carrier was a porous film. Inventive two roll sheet material was placed on a cross-matching machine as described in US Pat. No. 5,173,138. This sheet material was PBO to PBO, crossed at 0 ° / 90 °, consolidated under a temperature of 115 ° C. and a pressure of 500 psi (3.5 MPa), two identical PBO fiber lamina and double-sided porous polyethylene A laminate having a film was prepared. Polyethylene film had a water vapor permeability of ASTM E96-95 measured at 37.8 ° C. The ^{(Procedure E) 75 × 10 -9} cm 3 (stp) / (cm · sec · Pa).

  Twenty-two laminates were bonded together by molding at a temperature of 115 ° C. and a pressure of 1,000 psi (6.9 MPa) to form a composite of the present invention. The composite meets the requirements of NIJ Standard 0101.04 Revision A for Type IIA personal protective clothing and the requirements of NIJ Standard 0115.00 for Type I piercing protection and has an initial V50 after 4 weeks at 70 ° C. and 80% relative humidity. Retained above 87% of value.

Example 5
PBO fabric having a thickness of 8 mil (0.02 cm) and an areal density of 136 g / m ² [Hexcel-Schwebel style 530 fabric made of SYRON (registered trademark) AS500 denier fiber manufactured by Toyobo Co., Ltd.] In a bath containing an 8% by weight solution of a styrene-isoprene-styrene block copolymer elastomer [KRATON® D1107, from Kraton Polymers, Inc.] in anhydrous cyclohexane containing less than 0.1% by weight of water. The lower part of the roll immersed in was passed. Each filament of the fabric was completely coated with the solution. The fabric was passed through a squeeze roll to remove excess solution, placed on a carrier film of polyethylene film 0.35 mil (0.00089 cm), and passed through a heating oven to evaporate the solvent. This carrier net and the coated fabric of the present invention were then wound on a roll in preparation for the production of a ballistic article as described below and in Example 6 below.

The total area density of the fiber and sealant was 143 g / m ² . The area density of the sealant in the dry woven fabric was 7 g / m ² . The volume fraction between fibers filled with sealant was measured as follows: The volume occupied by 1 m ^{2 of} uncoated fabric was 100 cm × 100 cm × 0.02 cm = 200 cm ³ . The volume that is actually occupied by the fibers of 1 m ² of the fabric that are not coated was ^{136g / 1.54g / cm 3 = 88.3cm} 3. Volume between the fibers was therefore 200cm ³ -88.3cm ³ = 111.7cm ^3. The volume occupied by the sealant was 7 g / 0.92 g / cm ³ = 7.6 cm ³ . Therefore, the sealant accounted for 7.61 cm ³ /111.7 cm ³ × 100 = 6.8% of the volume between the fibers.

  Articles for ballistic testing were formed from 22 coated fabrics with a polyethylene film on one side having a lateral dimension of 40 cm × 40 cm stacked. One such article was placed in standard atmospheric conditions. Other such articles were subjected to accelerated aging for 4 and 6 weeks at 70 ° C. and 80% relative humidity. All articles were returned to standard atmospheric conditions for a minimum of 3 days prior to ballistic testing. The article of the present invention meets the requirements of NIJ Standard 0101.004 Revision A for Type IIA body armor and NIJ Standard 0115.00 for Type I piercing protection and after 4 weeks at 70 ° C. and 80% relative humidity. Maintained above 87% of initial V50 value.

Example 6
The polyethylene film carrier net was peeled from the PBO fabric of the present invention prepared in Example 5 above. Eleven pieces having a lateral dimension of 40 cm × 40 cm were cut from this fabric and each piece was divided into two aramid fabrics of the same size (31 × 31 850 denier Kevlar® per inch plain fabric) Each of the 11 woven sandwiches formed in this way was sandwiched between Hexel-Schwebel style 705 made of KM-2 fibers at a temperature of 115 ° C. under a pressure of 500 psi (3.5 MPa). The laminate of the present invention was produced by compression molding with 11 sheets, and 11 laminates were laminated and their peripheries were sewn together to form another article of the present invention.

  The article of the present invention meets the requirements of NIJ Standard 0101.004 Revision A for Type IIA body armor and NIJ Standard 0115.00 for Type I piercing protection and after 4 weeks at 70 ° C. and 80% relative humidity. Maintained above 87% of initial V50 value.

Example 7
PBO fiber [ZYLON (registered trademark) AS] chopped to a length of 51 mm was obtained from Toyobo Co., Ltd. The chopped fiber was formed into an irregularly oriented nonwoven sheet by a process of placing it in an air stream. This non-woven sheet (batt) was passed through a needle loom, the fibers were mechanically oriented in the vertical direction, and the fibers were collected to form a cohesive felt fabric. This PBO felt fabric was then added to a poly (isobutylene) elastomer in anhydrous cyclohexane containing less than 0.1% water by weight (VISTANEX® PIB MM 1-100, ExxonMobil Chemical Co.). The product was passed under a roll immersed in a bath containing a 10% by weight solution. The sealant was a water vapor of 0.28 × 10 ⁻¹¹ cm ³ (stp) · cm / (cm ² · sec · Pa) measured at 37.8 ° C. by ASTM standard test method E96-95 (Procedure E). Permeability and had an initial tensile modulus of less than 6,000 psi (41.3 MPa) as measured by ASTM D638.

  Each filament of felt fabric was completely coated with this solution. The fabric was passed through a squeeze roll to remove excess solution, placed on a 0.35 mil (0.00089 cm) polyethylene film carrier net, and passed through a heated oven to evaporate the solvent. The sealant occupied 10% of the volume between the fibers. A 1 mil (0.0025 cm) porous polyethylene film was applied to the upper surface of the felt fabric, and the assembly was passed between heated rolls at a temperature of 115 ° C. and a pressure of 500 psi (3.5 MPa) to obtain the fibrous sheet of the present invention. Produced.

  Articles for ballistic testing were formed from 22 coated felt fabrics using polyethylene film on both sides, having a lateral dimension of 40 cm x 40 cm, stacked together and stitched around. One such article was placed in standard atmospheric conditions. Other articles were subjected to accelerated aging for 4 and 6 weeks at 70 ° C. and 80% relative humidity. All articles were returned to standard atmospheric conditions for a minimum of 3 days prior to ballistic testing. The article of the present invention meets the requirements of NIJ Standard 0101.004 Revision A for Type IIA personal protective clothing and the requirements of NIJ Standard 0115.00 for Type I piercing protection and at 70 ° C. and 80% relative humidity for 4 weeks. Later, 87% of the initial V50 value is retained.

  Although the present invention has been described in considerable detail, such details need not be strictly followed, and all further changes and modifications fall within the scope of the invention as defined by the appended claims. It will be understood that this can be suggested to those skilled in the art.

It is the schematic of the method of manufacturing the unidirectional PBO fiber sheet of this invention.

Claims (47)

A method of forming a sheet comprising PBO fibers and exhibiting resistance to the effects of heat and moisture,
a) forming a fibrous sheet comprising a plurality of PBO fibers in a fiber network;
b) encapsulating the PBO fibers in a sealant by anhydrous means, the sealant being 25 × 10 5 measured at 37.8 ° C. according to ASTM E 96-95 (Procedure E). A step having a water vapor transmission rate of less than ^-11 cm ³ (stp) · cm / (cm ² · sec · Pa), and c) partially filling the volume between the fibers with the sealant;
d) optionally, adhering a plastic film to at least one side of the fibrous sheet.   The method according to claim 1, wherein the PBO fibers constitute 10 to 100% by weight of the fiber content of the sheet.   The method of claim 1, wherein the fiber network is selected from the group consisting of felt, knitted fabric, braid, woven fabric, randomly oriented planar nonwoven fabric, and unidirectionally oriented nonwoven fabric.   The method of claim 1, wherein the fibers in the network are aligned in one direction such that they are substantially parallel to each other.   The method of claim 1, wherein the sealant fills 5% to 99% of the volume between the fibers.   The method of claim 1, wherein the sealant fills 15% to 95% of the volume between the fibers. The sealant has a water vapor transmission rate of less than 5 × 10 ⁻¹¹ cm ³ (stp) · cm / (cm ² · sec · Pa) as measured by ASTM E 96-95 (Procedure E) at 37.8 ° C. The method of claim 1 comprising:   The anhydrous means for encapsulating the fibers is selected from the group consisting of chemical vapor deposition, gas phase polymerization, drying after polymerization in an anhydrous solution, drying after coating with an anhydrous sealant solution The method of claim 1.   The method of claim 1 wherein the anhydrous means of encapsulating the fibers is drying after coating with an anhydrous sealant solution.   The method according to claim 9, wherein the solvent in the anhydrous sealant solution has a boiling point of less than 150 ° C. under normal pressure.   The method according to claim 9, wherein the solvent in the anhydrous sealant solution has a boiling point of less than 100 ° C. under normal pressure. A method of forming an anti-ballistic article comprising PBO fibers and retaining at least 87% of the initial V50 value after adjustment for 4 weeks at 70 ° C. and 80% relative humidity comprising:
a) forming a fibrous sheet comprising a plurality of PBO fibers in a fiber network;
b) encapsulating the PBO fibers in a sealant by anhydrous means, the sealant being 25 × 10 5 measured at 37.8 ° C. according to ASTM E 96-95 (Procedure E). ^-11 and steps have ^{cm 3 (stp) · cm /} (cm 2 · sec · Pa) water vapor transmission rate of less than,
c) partially filling the volume between the fibers with the sealant;
d) optionally, bonding a plastic film to at least one side of the fibrous sheet;
e) stacking a plurality of fibrous sheets together in an unbonded or lightly bonded array. A method of forming a ballistic article comprising PBO fibers and retaining at least 87% of the initial V50 value after adjustment for 4 weeks at 70 ° C. and 80% relative humidity,
a) arranging a plurality of PBO fibers on a unidirectional, planar sheet;
by b) means of anhydrous said PBO fibers in a sealant comprising the steps of encapsulating, the sealant, ASTM E96-95 (Procedure E) by measured at 37.8 ° C. and 25 × 10 ^- Having a water vapor transmission rate of less than ¹¹ cm ³ (stp) · cm / (cm ² · sec · Pa) and partially filling the volume between the fibers;
c) bonding the fibers together to form a coherent sheet;
d) stacking the first and second sheets of the cohesive sheet together, wherein the direction of the fibers in the first sheet is at least 30 relative to the direction of the fibers in the second sheet. A step of an angle of °,
e) bonding the first and second cohesive sheets together to form a laminate;
f) optionally bonding a plastic film to one or both sides of the laminate;
g) stacking a plurality of laminates together in an unbonded or lightly bonded arrangement. The fiber network has a water vapor transmission rate of less than 25 × 10 ⁻¹¹ cm ³ (stp) · cm / (cm ² · sec · Pa) as measured by ASTM E96-95 (Procedure E) at 37.8 ° C. A fibrous sheet comprising PBO fibers encapsulated with a sealing agent having the sealing agent filling 5 to 99% of the volume between the fibers, and in some cases, one side of the fibrous sheet Or a fibrous sheet having a plastic film bonded on both sides.   21. The fibrous sheet according to claim 20, wherein the fiber network is selected from the group consisting of felt, knitted fabric, braid, woven fabric, irregularly oriented planar nonwoven fabric, and unidirectionally oriented nonwoven fabric.   The fibrous sheet according to claim 20, wherein the fibers in the fiber network are arranged in one direction so as to be substantially parallel to each other.   The fibrous sheet according to claim 20, wherein the sealant fills 15% to 95% of the volume between the fibers.   The fibrous sheet according to claim 20, wherein the PBO fiber is poly (2-phenylene-2,6-benzobisoxazole).   The fibrous sheet according to claim 20, wherein the PBO fibers constitute 10 to 100% by weight of the fiber content of the article.   The fibrous sheet according to claim 20, wherein the sealant constitutes 1 to 50% by weight of the article.   The fibrous sheet according to claim 20, wherein the sealant constitutes 5 to 25% by weight of the article.   The fibrous sheet according to claim 20, wherein the sealant constitutes 5 to 20% by weight of the article. The sealant has a water vapor transmission rate of less than 5 × 10 ⁻¹¹ cm ³ (stp) · cm / (cm ² · sec · Pa) as measured by ASTM E96-95 (Procedure E) at 37.8 ° C. The fibrous sheet according to claim 20.   21. The fibrous sheet of claim 20, wherein the sealant is an elastic material having an initial tensile modulus of less than 6,000 psi (41.3 MPa) as measured by ASTM D638.   The fibrous sheet according to claim 20, wherein the plastic film is a member selected from the group consisting of polyolefin, polyamide, polyester, polycarbonate, ionomer, cellulose, cellulose ester, ethyl cellulose, and polyfluorocarbon. The plastic film has a water vapor transmission rate of 5 × 10 ⁻⁹ cm ³ (stp) · cm / (cm ² · sec · Pa) or more as measured by ASTM E96-95 (Procedure E) at 37.8 ° C. The fibrous sheet according to claim 20. The plastic film has a water vapor transmission rate of 50 × 10 ⁻⁹ cm ³ (stp) · cm / (cm ² · sec · Pa) or more as measured by ASTM E96-95 (Procedure E) at 37.8 ° C. The fibrous sheet according to claim 20.   The fibrous sheet according to claim 20, wherein the plastic film is porous.   The fibrous sheet according to claim 20, wherein the plastic film constitutes 1 to 40% by weight of the sheet.   21. An article comprising a plurality of the fibrous sheets according to claim 20 in a stacked arrangement, wherein the fibrous sheets are not joined together or are lightly joined together.   37. The article of claim 36 that meets at least the requirements of NIJ Standard 0101.04 Revision A for Type IIa body armor. The article of claim 36 having at least specific energy absorption ^300J-m 2 / Kg, and 9mmGeco, 124 grain, V50 values FMJ least 1,300ft / sec upon impingement by (steel jacket) bullets (396m / sec) .   21. A laminate comprising one or more fibrous sheets according to claim 20, sandwiched between one or more fibrous sheets of high strength fibers of other compositions that are bonded together with a stacked arrangement. A laminate having a plastic film optionally adhered to one or both sides of the laminate.   21. A laminate comprising, in order, first, second, third, and fourth thin layers, wherein the first and fourth thin layers comprise aramid fibers, and the second and third thin layers. 40. A laminate according to claim 39 comprising the fibrous sheet of claim.   The first and fourth thin layers include unidirectional aramid fibers, the directions of the fibers in the first and fourth thin layers are perpendicular to each other, and the second and third thin layers The fiber sheet according to claim 22, wherein directions of the second and third thin layers are perpendicular to each other, and the fiber direction of the first thin layer is the second thin layer. 41. The laminate of claim 40, wherein the laminate is perpendicular to the fiber direction in the layer, and the direction of the fibers in the third thin layer is perpendicular to the direction of the fibers in the fourth thin layer.   23. A laminate comprising a plurality of unidirectional, fibrous sheets of claim 22 bonded together in a stacked arrangement, wherein the fiber orientation in any sheet is the fiber orientation in an adjacent sheet. And a laminate having a plastic film which is at an arbitrary angle and optionally adhered to one or both sides of the laminate. 43. The laminate according to claim 42, wherein the sealant has an initial tensile modulus of 1 x 10 < ⁶ > psi (6.9 GPa) or greater as measured by ASTM D638.   23. First and second unidirectional fibrous sheets according to claim 22 are bonded together in a stacked arrangement, wherein the direction of the fibers in the first sheet is in the second sheet 43. The laminate of claim 42, wherein the laminate is at an angle of at least 30 degrees with respect to the fiber direction.   45. An article comprising a plurality of laminates according to claim 44 in a stacked arrangement, wherein the laminates are not bonded to each other or are lightly bonded.   43. The article of claim 42, which meets at least the requirements of NIJ Standard 0101.04 Revision A for Type IIa body armor. 9MmGeco, 124 grain, article of claim 42 having a V50 value of FMJ specific energy of at least ^300J-m 2 / Kg upon impingement by (steel jacket) bullet absorption and at 1,300ft / sec (396m / sec) .   43. The article of claim 42 having a retention of 87% or more of the initial V50 value after 4 weeks of accelerated aging at 70 [deg.] C and 80% relative humidity.   43. The article of claim 42 having a retention of 85% or more of the initial V50 value after an accelerated aging test at 70 [deg.] C. and 80% relative humidity for 6 weeks.   43. The article of claim 42, which meets at least the requirements of NIJ standard 0115.00 for Type 1 piercing protection.   The fibers are encapsulated by an anhydrous method selected from the group consisting of chemical vapor deposition, gas phase polymerization, drying after polymerization in an aqueous solution free, and drying after coating with an anhydrous sealant solution. The fibrous sheet according to claim 20.   The fibrous sheet according to claim 20, wherein the fibers are encapsulated by drying after coating with an anhydrous sealant solution. Covered with a sealant having a water vapor transmission rate of less than 25 × 10 ⁻¹¹ cm ³ (stp) · cm / (cm ² · sec · Pa) as measured by ASTM E96-95 (Procedure E) at 37.8 ° C. Wrapped PBO fiber.

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