RU2756749C2 - Method for manufacturing anti-fragmentation shielding canvas - Google Patents

Abstract

FIELD: armament.

SUBSTANCE: invention relates to the field of layered bullet-resistant materials made of ballistic fabric with shielding properties; it can be used in the manufacture of mass protection equipment. For the manufacture of canvas, aramid fibers are pre-prepared by etching in acid at a temperature from 20 to 40°C and a time from 5 to 60 seconds, depending on the acid concentration. Fibers prepared in this way are washed and metallized with acid in an aqueous salt solution in the presence of a catalyst to reduce the acid concentration on the fiber. Fibers are dried to remove excess moisture or acid. The activity of the fiber surface is provided for interaction with copper, for which salt with a palladium and tin cation is added to an aqueous solution of copper as a catalyst, and acid-etched and washed fibers are immersed in it and mixed. The fiber surface is saturated with minerals, for which fibers are immersed in an accelerator bath with dilute mineral acid. Metallization is carried out directly, for which fibers are placed or passed through a metallization bath, in which copper ions are mixed with a formaldehyde catalyst and a preferred copper concentration of 1-5 g/l. Fibers are mixed for 10-20 minutes for active metallization at temperatures from 10 to 60°C. Metallized fibers are removed from the bath. Mesh is made of metallized fibers according to the Faraday cell principle, based on the calculation of the greatest effective shielding of electromagnetic radiation in the range from 20 MHz to 6 GHz. In addition, mesh fibers are made of aramid fiber metallized with heavy metal ions.

EFFECT: invention provides for the creation of strong and lightweight anti-fragmentation canvas capable of shielding frequencies of a possible explosive device, isolating explosive or suspicious objects by preventing the initialization of explosive devices located in them, detonators of which are controlled via radio channels.

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Description

The invention relates to the field of laminated bullet-resistant materials from ballistic fabric with shielding properties, and can be used in the manufacture of mass protection.

The mass of the material in which metallized aramid fibers are used is significantly lower, since one layer is both splinterproof and shielding.

The prior art knows materials shielding against electromagnetic interference, for example: Aaronia X-Dream - a fabric shielding against electromagnetic interference (100 dB) [http://el-kor.ru/bezehovye-kamery-i-ekrankamery-ekraniruyushchie-materialy/ aaronia-x-dream-tkan-ekraniruyushchaya-ot-elektromagnitnyh-pomeh-100-db]. This fabric has a frequency range of shielded signals 1 MHz - 30 GHz, shielding efficiency - 70 dB; 99.999999% at 20 GHz. The material of the fabric is a mixture of copper and nickel, the backing is polyester. The type of shielded signals is HF and LF electric fields. Available size from 1 m² to 50 m². Wireless signals of standards practically do not penetrate through such fabric: GSM and / or DECT, and / or BLUETOOTH, and / or WLAN and other electromagnetic signals in the range from 1 MHz to 30 GHz.

Known PROTECTIVE STRUCTURE OF ANTI-SHIPPING COVER WITH NON-WOVEN MATERIAL (RF Patent 2237846, published: 10.10.2004 Bull. No. 28), containing layers of woven and two outer layers of non-woven ballistic-resistant materials, connected by sewing stitches in two mutually perpendicular directions non-woven material is made composite, divided into parts by single layers of woven material, parts of each layer are interconnected by sewing lines in two mutually perpendicular directions, the distance between the lines is 0.25 ... 0.5 distance between the lines connecting the entire protective structure, when The surface density of the nonwoven material is 35 ... 55% of the surface density of the composite outer layers and 5 ... 20% of the surface density of the entire protective structure.

The disadvantage of this solution is the multi-layered structure and the impossibility of shielding the frequencies of a possible explosive device (hereinafter referred to as an explosive device), controlled by a radio channel.

As the closest source of information, you can take a method of manufacturing composite materials containing conductive nanofillers according to patent No. 2611512 (published: February 27, 2017, bulletin No. 6), including mixing or dispersing a first composition containing one or more conductive nanofillers and one or more polyarylethersulfone thermoplastic polymers (A), with or in one or more precursors (P) of an uncured thermosetting resin and optionally one or more curing agents for said resin. Also described is a composite containing the specified composition and reinforcing fibers, and these fibers are present in a concentration of from 5 to 70 wt.%.

The technical problem of the present invention lies in the need to create a durable and lightweight anti-splinter cloth, at the same time, capable of shielding the frequencies of a possible WA.

The technical result consists in providing the possibility of isolating explosive or suspicious objects by preventing the initialization of an explosive device located in them, the detonator of which is controlled by a radio channel.

The anti-splinter fabric is made of aramid fibers, the most durable material available.

It is known that the frequency range from 100 MHz to 6000 MHz is most often used for remote initiation of a VU. The shielding efficiency S_c, which depends on the frequency, material, thickness and linear dimensions of the shielding mesh cell, can, for example, be determined by the following formula:

S_c = λ / 2s [ln (2πr / s)], (1)

where r is the radius of the mesh wire, s is the mesh step, λ is the radiation wavelength.

Example. To calculate the shielding grid for 900 MHz radiation, the shielding grid was calculated. Center frequency f = 900 MHz. Mesh wire diameter d = 1.5 mm. Permissible seepage loss p = 1%. The maximum cell size of the screening mesh is b = 4.6 mm. The signal loss due to leakage through the grid was -0.04 dB.

The novelty of the claimed invention is that the grid, which allows maximum retention of fragments and prevents the initiation of a radio-controlled explosive device, made with the expectation of the most effective shielding of electromagnetic radiation (hereinafter - EMP) in the range from 20 MHz to 6 GHz (for example, using the expression (1), performed according to the Faraday cage principle of aramid fibers metallized with heavy metals The process of metallization of aramid fibers can be carried out according to one of the known methods, for example, according to RF patent 2144965.

The most suitable metal for shielding is copper. The first stage of metallization in this case is pre-pickling - contacting aramid fibers with a pre-treatment acid (this can be aqueous nitric acid, or chlorofluorosulfonic acid in an organic liquid that does not react with acids). This process is carried out at a temperature of 20 to 40 ֯ C and at a time of 5 to 60 seconds, depending on the concentration of the pre-treatment acid (within 75-95%), if the fibers are in contact for more than 120 seconds in certain cases, then they are destroyed. The purpose of the first stage is to create some structural changes and microcracks on the fiber surface to facilitate further better adhesion of the metal to the fiber.

After pickling, the fibers are washed either with water to reduce the concentration of acid on the fiber, or with a base or basic sodium bicarbonate salt to neutralize the acid and remove it from the fiber. Then, desirably, but not necessarily, the fibers are dried to better remove excess moisture or acid, then a salt with a palladium and tin cation as a catalyst is added to an aqueous solution of copper, and the acid-etched and washed fibers are immersed in it and mixed to ensure surface activity fibers to interact with copper. Then, the fibers are removed from this solution, and, if necessary, immersed in an accelerator bath with dilute mineral acid to saturate the fiber surface with minerals.

Next, the metallization stage begins directly, for this, the fibers are placed or passed through a metallization bath, in which there are copper ions in a mixture with formaldehyde (catalyst), the copper concentration in these cases is diverse, but the more preferable copper concentration is 1-5 g / l, the fibers in the bath is moderately stirred for 10-20 minutes for active metallization, if the speed suddenly decreases, then formaldehyde, a pH-correcting alkaline solution and a solution with copper ions are added to the bath. All this is carried out at various temperatures from 10 to 60 ֯ C, but more preferably 20-40 ֯ C, after which the metallized fibers are removed from the bath.

In the case of metallization with silver, the method is carried out under similar conditions, only after etching is the washing of a solution of tin chloride and hydrochloric acid used, and a mixture of silver nitrate and ammonia is used in the metallization stage.

Similarly, metallization is carried out with nickel, and with cobalt, and with other metals.

Claims (2)

1. A method of manufacturing an anti-splinter shielding fabric from a bullet-proof, splinter-resistant ballistic fabric made of aramid fibers, with preliminary preparation of aramid fibers by etching in acid at a temperature of 20 to 40 ° C and at a time from 5 to 60 seconds, depending on the concentration of acid ; subsequent washing of the fibers and metallization of the thus prepared aramid fibers of acid in a water-salt solution in the presence of a catalyst to reduce the concentration of acid on the fiber, then dry to remove excess moisture or acid, ensure the activity of the fiber surface for interaction with copper, for which in an aqueous solution of copper add salt with a cation of palladium and tin as a catalyst and immerse the acid-etched and washed fibers therein and mix; then saturating the surface of the fiber with minerals, for which the fibers are immersed in an accelerator bath with dilute mineral acid; and metallization is carried out directly, for which the fibers are placed or passed through a metallization bath, in which there are copper ions in a mixture with a catalyst formaldehyde, while the preferred concentration of copper is 1-5 g / l, stirred for 10-20 minutes for active metallization, at temperatures from 10 to 60 ° C, after which the metallized fibers are removed from the bath, characterized in that a mesh is made from the metallized fibers according to the Faraday cage principle based on the greatest effective shielding of electromagnetic radiation in the range from 20 MHz to 6 GHz; in addition, the fibers of the mesh are made of aramid fiber metallized with heavy metal ions. 2. A method of manufacturing an anti-splinter shielding fabric according to claim 1, characterized in that the shielding efficiency can be calculated by the formula, where S_c, depending on the frequency, material, thickness and linear dimensions of the shielding mesh cell, can be determined by the following formula S_c = λ / 2s [ln (2πr / s)], where r is the radius of the mesh wire, s is the mesh step, λ is the radiation wavelength.