BR102020012664A2 - COMPOSITE MATERIAL BASED ON THERMOFIXED POLYMER BASED POLYESTER REINFORCED WITH NATURAL CARNAÚBA FIBERS, PRODUCTION PROCESS AND USE IN BALLISTIC SHIELDING - Google Patents

Abstract

composite material based on thermosetting polyester polymer reinforced with natural carnauba fibers, production process and use in ballistic armor. The present invention describes a composite material produced with a thermosetting polymer based on polyester resin, reinforced with layers of continuous and aligned carnauba fibers, a natural fiber scientifically identified as copernicia prunifera. The characteristics of this composite material, technically known as a composite, are such that they make it as resistant as it is economically advantageous for use in multilayer ballistic armor aimed at protecting against rifle shots with high-impact ammunition. This composite makes it possible to replace much more expensive synthetic materials currently used in the armed forces around the world, such as the aramid fiber fabrics commercially known as Kevlar®. The present invention also describes technical details relevant to the production of the composite, including the composition range as well as the temperature and pressure conditions suitable for its ballistic performance.

Description

COMPOSITE MATERIAL BASED ON THERMOFIXED POLYMER BASED POLYESTER REINFORCED WITH NATURAL CARNAÚBA FIBERS, PRODUCTION PROCESS AND USE IN BALLISTIC SHIELDING Field of Invention

[001] The present invention describes a composite material, technically known as composite, obtained by reinforcing carnauba fibers, produced from a natural fiber, Copernicia prunifera, inside a polyester polymer matrix. This composite has characteristics suitable for application in multilayer ballistic armor aimed at protection against rifle fire with high impact ammunition. The present invention also discloses the process for manufacturing the material.

Background of the Invention

[002] Materials composed of polymer matrix reinforced with fibers or natural fabrics, produced from these fibers, have been used since the middle of the 20th century in industrial sectors such as automobiles and civil construction. However, there is no record of use in armor for ballistic protection.

[003] In ballistic protection used in personal vests and military vehicles, in addition to metallic and ceramic materials, polymeric compounds reinforced with fibers or synthetic fabrics are also used.

[004] In isolation, polymeric composite materials reinforced with fibers or natural fabrics do not have satisfactory ballistic performance. However, as an intermediate part of a multilayer system, they have performance comparable to synthetic materials and a much lower cost.

[005] Patent document PI 8800573-A (Brazil, 1989) describes a “Rigid composite of polyester, phenolic or polyamide resin matrix reinforced with continuous p-aramid filaments coated with about 0.2 to 5% by weight, of a solid adhesion modifier, of significantly improved ballistic performance, lighter weight, and reduced area density for a given level of ballistic performance”, however it is not about natural fiber or fabric, only polyamide which is synthetic and expensive.

[006] WO2010/091476-A1 (USA, 2010), describes a “Ballistic fabric composed of 65 to 80% of polyamide fibers interwoven with 20 to 35% of animal fibers or cotton. The preferred animal fiber is wool and the preferred blend is 25% wool with 75% polyaramid fibers. The preferred polyaramid is Kevlar”. Unlike the present invention, only ¼ of the fibers of natural fibers, animal or cotton, are blended with ¾ of synthetic fibers.

[007] The document JP5877431-132 (Japan, 2011) describes a “A fiber reinforced composite material comprises a wavy composite fiber yarn 1 which is formed by the wound stitch of an enveloping yarn 5 of a thermoplastic synthetic fiber yarn in a carbon fiber bundle 3 and/or a natural fiber yarn 4 with these yarns subjected to varying tension”. However, the composite only uses synthetic, thermoplastic or carbon fibers.

[008] WO2012/093167-A1 (France, 2012) describes an “Injectable composite material, including: (a) 28 to 95% by weight of a polypropylene/polyethylene copolymer; (b) 0 to 10% by weight of a flow enhancer; (c) 1 to 20% by weight of an impact modifier; (d) 1 to 20% compatibilizing agent; and (e) 3 to 70% by weight of natural fibers, wherein the polypropylene/polyethylene copolymer forms a matrix. The invention also relates to a method for preparing said composite material, as well as a method for using it in the manufacture of parts by injection or overmolding”. Although it is a natural fiber reinforced composite, there is no indication for use in ballistic armor.

[009] The document CN207904438-V (Chile, 2018) describes “Strong and durable yarn based on a mixture of natural jute and PET, which consists of a composite comprising the layer of jute fiber, the fiber layer of polypropylene, the PET fiber layer, the polyurethane fiber layer, the adhesive layer and the nylon fiber layer”. Although it contains jute fiber, there is no indication that the wire can be used in shielding.

[0010] None of the patent documents mentioned above is similar to the present invention as they do not specifically deal with a composite reinforced exclusively with continuous and aligned fibers (carnauba fiber) for use in multilayer ballistic armor.

Summary of the Invention

[0011] The general objective of the invention is to produce a polymer matrix composite material reinforced with continuous and aligned fibers of carnauba, to be used for the first time as part of a multilayer ballistic armor system.

[0012] The specific objective is to manufacture composite material boards based on 60% by volume of reinforced polyester polymer with 40% by volume of carnauba fibers uniformly allocated on the board.

[0013] The manufacture of epoxy composite plates with carnauba fibers is done in a metallic mold under pressure of 5 MPa for 24 hours at room temperature. After removal from the mold, the plate is further cured at a specific temperature and time.

[0014] It is the final objective of this invention the use of composite material plate as part of a multilayer armor system for protection, personnel and military vehicles, against rifle firing with high impact ammunition.

Brief Description of Figures

[0015] Figure 1 illustrates the metal mold where the composite material plate is processed. Figure 2 illustrates the fibers used to produce the composite. Figure 3 illustrates a composite plate with a polyester polymer matrix reinforced with carnauba fibers (Copernicia prunifera). Figure 4 represents a multilayer shielding system, as shown by the following invention.

Detailed Description of the Invention

[0016] The materials used in this invention correspond to: (i) rigid and high viscosity orthophthalic unsaturated polyester resin together with the catalyst based on methyl ethyl ketone, both commercially available in Brazil; (ii) carnauba fibers obtained in Brazil, specifically in the state of Ceará.

[0017] The manufacture of the composite plate is done in a steel mold, illustrated in Figure 1, with a filling base and a closing cap. Screws connecting the two parts of the mold allow total sealing and ease of release.

[0018] The steel mold described in item [0017] is produced to order in a specialized mechanical workshop, found in any large city in the country.

[0019] To facilitate the demolding of the plate, silicone grease, available in Brazil, is used before the process, applied to the internal surfaces of the mold.

[0020] The manufacturing process consists of accommodating continuous fibers of carnauba with the same length, with the same internal dimension of the mold, with orthophthalic polyester resin mixed with the catalyst based on methyl ethyl ketone. The interleaved amount of 40% of carnauba fibers is determined in advance based on the density of the materials used.

[0021] After filling the mold with carnauba fibers interspersed with a resin/catalyst liquid mixture, the mold lid is placed, closed with the aid of screws. The filled mold is closed and then taken to a hydraulic press, with a capacity of 30 tons, and commonly available in Brazil.

[0022] The mold installed in the press is then subjected to a pressure of 5 MPa that allows complete flow of the resin/catalyst liquid mixture through the carnauba fibers.

[0023] The mold, filled and under pressure, remains for 24 hours at room temperature, which allows the epoxy resin to harden by the action of the TETA catalyst.

[0024] The demoulding of the plate is carried out by the inverse action of the screws that sealed the plate.

[0025] The demolded plate, as illustrated in Figure 3, is taken to an oven for post-curing the polyester matrix at a controlled temperature and time in order to reach the maximum strength and toughness of the composite.

Use of Composite in Ballistic Armor

[0026] The composite material of polyester matrix reinforced with continuous and aligned fibers of carnauba has as main purpose the use in the form of a plate for a multilayer armoring system aiming to protect against rifle firing with high impact ammunition. This protection corresponds to level III of the international standard related to projectile caliber 7.62 mm or 5.56 mm.

[0027] In the multilayer armor system, ceramic platelets make up the frontal layer responsible for projectile erosion and dissipation of much of the impact energy. The composite plate, as a second layer, is bonded to the ceramic platelets with polyurethane adhesive.

[0028] The composite plate, as a second layer, has the function of capturing the cloud of fragments resulting from the impact of the projectile against the front layer of ceramic platelets.

[0029] The capture of the fragments by the composite plate occurs by mechanisms of encrustation in the carnauba fibers in the composite. The fragments, both metallic from the projectile and ceramic from the front layer, are much harder and easily penetrate the softer carnauba fibers.

[0030] The amount of 40% of carnauba fibers in the composite is enough to prevent the fragmentation of the fragile polymeric polyester matrix. This allows the composite plate to maintain its integrity to protect against subsequent rifle fire.

[0031] The ballistic performance of the epoxy composite plate reinforced with continuous and aligned fibers of carnauba is comparable to that of plates, with the same dimension, made with synthetic fabrics such as Kevlar® which is at least 5 times more expensive.

Preparation Process

[0032] In a preferred embodiment of the invention, the process of preparing composite material comprises the steps of:

[0033] a) Prepare the carnauba fibers.

[0034] b) Prepare the amount of fibers to 40% vol. of the composite.

[0035] c) Prepare polyester resin for composite production.

[0036] d) Pour the polyester resin into the metallic matrix until the bottom is completely wet.

[0037] e) Slowly add the fibers together with the polyester resin, ensuring that they are all wetted by the resin.

[0038] f) Press this mixture at room temperature through a hydraulic press with 5 tons of force for 24 hours.

[0039] g) Unmold the composite plate.

[0040] h) Assemble the multilayer ballistic armor

[0041] The importance of manufacturing a composite is the homogeneity and continuity in its properties, which improve the dissipation of projectile impact energy while maintaining its integrity after this request. In conjunction with ceramic material, it can be applied to 9mm (tier III-A) bulletproof vests so that they are optimized to withstand Tier III threats.

Claims (10)

Composite material characterized by being constituted of a thermosetting polymer matrix reinforced with natural fibers. The composite material mentioned in claim 1 is, in engineering terms, known as a composite characterized by the fact that it has good adhesion of the dispersed phase, which is a set of natural fibers, and the polymeric matrix as a continuous phase. The composite described in claim 2 will be subjected to the process characterized by the joining of the polyester polymer matrix incorporated with 40% by volume of natural carnauba fiber. The composite preparation process described in claim 3 is characterized by the following steps:

• ● Accommodate layers of carnauba fibers, in a continuous and aligned manner, corresponding to the desired proportion of 40% by volume within a suitable metallic mold, which has the dimensions of 1 cm thick by 15 cm long and 12 cm wide;
• ● Add still fluid polyester resin and cap the mold.

The processing details described in claim 4 are characterized by:

• ● Use a rectangular metal mold with ballistic plate dimensions for use in a personal vest or military vehicle;
• ● Apply a pressure of 5 MPa at room temperature for a period of 24 hours in the capped mold, already filled with layers of fabric and polyester resin.

Process characterized by claims 3 to 5 allows the manufacture of plates with a thickness of up to 50 mm and lateral dimensions of up to 300 mm in carbon steel molds specified for this purpose. The process that follows claim 5 is characterized by the demolding of the plate with the aid of fitting screws, facilitated by the use of silicone grease, previously applied to the internal surface of the mold. The composite plate with continuous and aligned fibers of carnauba reinforcing a polyester matrix is characterized by being suitable for use as a layer in ballistic armor to protect against rifle fire with 7.62 mm or 5.56 mm ammunition. In multilayer armor, characterized by having the composite plate of the present invention glued with polyurethane adhesive to a ceramic front layer, responsible for eroding the projectile and attenuating its impact. The composite in the multilayer ballistic system is characterized by having the function of capturing the ceramic and projectile fragments resulting from the frontal impact.

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