Smokeless gunpowder for barrel systems containing a phlegmatizer for combustion retardation and method of preparing this gunpowder

Abstract

The invention relates to smokeless gunpowder for barrel systems, which contains powder grains, wherein the surface layer of each powder grain is provided with a phlegmatizer for retarding the combustion of the surface layer of each powder grain, characterized in that the surface layer of each powder grain contains 1 to 10 % by volume of a phlegmatizer, which is formed by either - sucrose acetate, sucrose benzoate, sucrose acetate butyrate, sucrose octaacetate or sucrose benzoate disaccharide esters or sucrose diacetate hexaisobutyrate or - a combination of sucrose acetate, sucrose benzoate, sucrose acetate butyrate, sucrose octaacetate or sucrose benzoate disaccharide esters, or sucrose diacetate hexaisobutyrate with benzyl esters of salicylic acid, especially benzyl salicylate, or - a combination of sucrose acetate, sucrose benzoate, sucrose acetate butyrate, sucrose octaacetate or sucrose benzoate disaccharide esters or sucrose diacetate hexaisobutyrate with phenyl esters of salicylic acid, especially phenyl salicylate, or - a combination of sucrose acetate, sucrose benzoate, sucrose acetate butyrate, sucrose octaacetate or sucrose benzoate disaccharide esters or sucrose diacetate hexaisobutyrate with compounds from the group of benzoates, especially diethylene glycol dibenzoate or dipropylene glycol dibenzoate. The invention also relates to a method of preparing this gunpowder for barrel systems.

Description

[0001] Smokeless gunpowder for barrel systems containing a phlegmatizer for combustion retardation and method of preparing this gunpowder

[0002] Technical field

[0003] The invention relates to smokeless gunpowder for barrel systems which contains powder grains where the surface layer of each powder grain is coated with a phlegmatizer to slow down the burning of the surface layer of each powder grain.

[0004] The invention also relates to a method of preparing smokeless gunpowder for barrel systems which contains powder grains where the surface layer of each powder grain is coated with a phlegmatizer to slow down the burning of the surface layer of each powder grain, in which a surface treatment is applied to preprepared powder particles to slow down the burning of the surface layer of the powder particles, where the surface treatment is performed either by applying a phlegmatizer to the powder grains in an aqueous environment using preprepared powder grains before drying the powder grains, or by spraying a phlegmatizer solution onto dry powder grains.

[0005] Background art

[0006] Smokeless gunpowders are powders designed to bum in the barrel of a weapon under controlled conditions. They are nitrocellulose, nitroglycerin, and diglycol (diethylene glycol dinitrate) powders. The burning rate of the powder can be influenced by the application of phlegmatizers (deterrents), which are incorporated into the top layer of the powder grain. Modifying the powder grain initially slows down the burning rate of the powder, thereby achieving controlled combustion of the powder charge. This process is called phlegmatization.

[0007] Currently, the phlegmatizer dibutyl phthalate (DBP), which is characterized by increased toxicity, is used for the phlegmatization of smokeless powder grains. Substances released in connection with the use of DBP for the phlegmatization of smokeless powder grains can cause damage to the reproductive abilities of living organisms, are also highly toxic to aquatic organisms, and have long-term effects. Another substance used for the phlegmatization of the surface layer of smokeless powder grains is centralite, which, however, forms toxic nitrosam ines.

[0008] Surface treatments of propellants basicd on polymers or other high molecular weight substances are known from the background art.

[0009] US 5 510 062 A discloses the phlegmatization of the surface layer of spherical propellants by cellulose acetate derivatives using a solution of cellulose acetate butyrate (CAB) or cellulose acetate propionate. The author demonstrates the difference in the concentration gradient of CAB polymer compared to polyester after one month of thermal aging. In CAB polymer, the difference in polymer movement within the propellant particles is negligible. However, the ballistic properties of the resulting propellant are not documented. Another disadvantage is the need to prepare a CAB solution, e.g., in ethyl acetate, and the long time required for the spherical propellant particles to absorb the polymer solution. Economically or ecologically, this is not an ideal solution and requires higher energy consumption. In US 5 510 062 A, polysaccharide acetate is dosed in a solvent solution, and the soaking time and subsequent distillation of the solvent is impractical (taking more than one work shift). Due to the higher energy consumption, preparation is also energy-intensive due to the long-term heating of the entire mixture and distillation of the solvent.

[0010] US 4 950 342 A discloses polymer polycaprolactone as a phlegmatizer of the surface layer. It is a thermoplastic that significantly slows down the combustion of the surface layer, but the authors do not prove this with measurements in a bomb calorimeter or weapon system. The authors describe the surface treatment of a propellant containing 29 % of nitroglycerin in an aqueous suspension. However, the disadvantage is the need to prepare a polymer solution and a relatively long diffusion of the solution into the surface layer of the propellant (according to the authors, 2-4 hours). It is therefore a relatively costly and lengthy process requiring the use of a volatile solvent.

[0011] US 3 704 185 A discloses the use of ethylene glycol dimethacrylate and triethylene glycol dimethacrylate for phlegmatization of single-component powders. The technology is particularly suitable for the so-called dry surface treatment, for wet treatment its suitability is limited due to the partial solubility of glycol acrylates in water. Another disadvantage is the relatively long drying time or many hours of heating in phlegmatization drums, i.e. high time and energy requirements. In addition, it is not a suitable technology for fine-grained spherical powders, because the flame retardancy in thin layers is often insufficient in the case of these substances. A similar substance is the Russian mixture of substances, so-called MGF-9.

[0012] US 3 798 085 A describes the preparation of a propellant with a nitroglycerin content of 15 %, where the surface layer is made of a special polyester (PES). The disadvantage is the production of PES from ethylene glycol, fatty and sebacic acids, as well as the long soaking time of PES into the propellant.

[0013] US 3 032 972 A discloses a method of regulating the burning rate of propellants used in jet and rocket engines. The patent mentions the use of sucrose octaacetate in combination with combustion catalysts to regulate the burning rate. Sucrose octaacetate is used here only as a nitrocellulose gelling agent for the propellant, while the burning rate is affected by catalysts containing metal (PbO). Sucrose octaacetate itself is not mentioned in this patent as a substance affecting the burning rate, because in rocket fuels the so-called Plateau effect caused by catalysts containing metal is observed (this is not related to the content of sucrose octaacetate). The patent focuses on rocket fuel as such and combustion retardation throughout the volume, not on smokeless gunpowders for barrel weapons, where combustion retardation of the surface layer is important.

[0014] US 3 764 416 describes the preparation of a low-energy, low-burn-rate propellant, which, due to its composition including aryl hydroxy compounds, heterocyclic nitramines as well as sucrose octaacetate, produces gaseous exhaust products that are unreactive towards widely used oxidizing agents. In addition, the propellant exhibits low pressure. Again, the use of sucrose octaacetate does not concern the combustion retardation of the surface layer of the propellant, but the gelling ability of sucrose octaacetate in the preparation of rocket fuel.

[0015] US 4 521 261 A discloses the use of sucrose octaacetate as a substance reducing the rate of combustion in the production of two-component cast or extruded propellants for rocket engines. This patent also does not deal with the retardation of the combustion of the surface layer of powder grains, but with the gelling ability of sucrose octaacetate in combination with nitroglycerin in the production of rocket fuel. In this case, it is necessary to add combustion catalysts (copper salts) to the propellants. Moreover, this does not concern the retardation of the combustion of the surface layer of the propellant.

[0016] EP 0 133 798 A2 discloses the use of sucrose octaacetate in two- component propellants to retard the combustion of fuel in rocket engines. The document describes two-component mixtures that are prepared by casting or extrusion. Nitrocellulose is mixed in a mixer with nitroglycerin dissolved in, for example, acetone, thereby gelatinizing it. During this process may be added, other additives, such as petroleum jelly or sucrose octaacetate. After thorough mixing, the mass is extruded using a press in the form of long fibres, which are then cut to the desired length and then dried. These small particles, which are dried, are then combined with a soaking liquid to form a rocket element.

[0017] The object of the invention is to reduce or eliminate the disadvantages of the background art, in particular to develop smokeless gunpowder for barrel systems with a phlegmatized surface and minimal toxic effects on human and aquatic organisms.

[0018] Principle of the invention

[0019] The object of the invention is achieved by smokeless gunpowder for barrel systems, which contains powder grains where the surface layer of each powder grain is coated with a phlegmatizer to slow down the combustion of the surface layer of each powder grain, whose principle consists in the application of 1 to 10 % by volume of a phlegmatizer, which consists of either sucrose acetate, sucrose benzoate, sucrose acetate butyrate, sucrose octaacetate or sucrose benzoate disaccharide esters or sucrose hexaisobutyrate diacetate, or a combination of sucrose acetate, sucrose benzoate, sucrose acetate butyrate, sucrose octaacetate, or sucrose benzoate disaccharide esters or sucrose hexaisobutyrate diacetate with benzyl esters of salicylic acid, especially benzyl salicylate, or a combination of sucrose acetate, sucrose benzoate, sucrose acetate butyrate, sucrose octaacetate or sucrose benzoate disaccharide esters or sucrose diacetate hexaisobutyrate with phenyl esters of salicylic acid, especially phenyl salicylate, or a combination of sucrose acetate, sucrose benzoate, sucrose acetate butyrate , sucrose octaacetate or sucrose benzoate disaccharide esters or sucrose diacetate hexaisobutyrate with compounds from the group of benzoates, especially diethylene glycol dibenzoate or dipropylene glycol dibenzoate. The phlegmatizer thus contains 0 % by volume of dibutyl phthalate or centralite. The application is carried out either in an aqueous emulsion, suspension, or solution before drying the powder grains, or by spraying after drying the powder grains, both for the purpose of slowing down the burning rate of the powder grains and reducing the toxicity of the smokeless gunpowder. The surface layer of the smokeless powder thus contains 1 to 10 % by volume of a phlegmatizer, which completely replaces dibutyl phthalate or centralite, which are used according to the background art and whose content according to the present invention is thus 0 % by volume. The smokeless gunpowder according to the invention is thus characterized not only by a regulated burning rate of the volume or surface layer, but also by reduced toxicity.

[0020] The principle of the method of preparation of smokeless gunpowder for barrel systems containing powder grains where the surface layer of each powder grain is coated with a phlegmatizer to slow down the burning of the surface layer of each powder grain consists in applying 1 to 10 % by volume of a phlegmatizer from the group of substances according to claim 1 either in an aqueous environment using pre-prepared powder grains before drying the powder grains, or by spraying a phlegmatizer solution onto dry powder grains.

[0021] In both cases, the good solubility of carbohydrate acetates in ethanol and mixtures of polar solvents is advantageous. Ethanol is low in toxicity in vapour form and has high exposure limits compared to other solvents. For example, sucrose octaacetate (SOA) belongs to a class of organic compounds known as o-glycosyl compounds. These are glycosides in which the sugar group is bound via one carbon to another group through an O-glycosidic bond. Sucrose octaacetate is odourless, its most distinctive feature being its bitterness. SOA is used in food supplements and cosmetics and is also found in pharmaceutical preparations and weed killers. The widespread use of SOA demonstrates its broad applicability and low toxicity. Sucrose octaacetate (SOA) has been approved by the US Food and Drug Administration (FDA) as a food additive.

[0022] Brief

[0023] The figure shows a graph of the gamma curve of tests performed in a bomb calorimeter on sample 1 according to the invention, on sample 2 according to the invention, and on a comparative sample of smokeless gunpowder phlegmatized with dibutyl phthalate according to the background art. of embodiment

[0024] The invention will be described with reference to smokeless gunpowder with phlegmatized powder grain and will also be described using two specific examples of phlegmatization of powder grain according to the invention.

[0025] Before the actual phlegmatization of the smokeless powder grain, the basic powder grain is prepared. The preparation of the basic powder grain is carried out using the so-called lacquer emulsion method, when a homogeneous suspension is created from nitrocellulose together with water under constant stirring in a reactor, to which ethyl acetate is subsequently added together with chemical stabilizers. In the case of two-component smokeless powders, nitroglycerin is also added. Under the action of ethyl acetate, the components of the suspension dissolve into a viscous lacquer, which then forms a lacquer emulsion in water. During preparation, for some types of powders, a dewatering agent is additionally added to the lacquer emulsion in water. In the final stage of preparation, the solvent is distilled off at an elevated temperature. After cooling again, the technological solution is separated and the powder grain is washed with water.

[0026] As a phlegmatizer (deterrent) according to the invention is used an organic compound from the group consisting of carbohydrate acetates (sucrose acetate, sucrose benzoate or sucrose acetate butyrate , etc.) or carbohydrate acetates in combination with other substances, e.g., o-glycosyl compounds (sucrose octaacetate), sucrose benzoate disaccharide esters or sucrose hexaisobutyrate diacetate or in combination of carbohydrate acetates with benzyl esters of salicylic acid (benzyl salicylate) or phenyl esters of salicylic acid (phenyl salicylate) or compounds from the group of benzoates (diethylene glycol dibenzoate, dipropylene glycol dibenzoate). The phlegmatizer also contains 0 % by volume of dibutyl phthalate or centralite, which means that it is free of dibutyl phthalate or centralite.

[0027] The surface treatment of the basic grain of smokeless powder using the phlegmatizer (deterrent) according to the invention is carried out after the preparation of the basic grain in a reactor in an excess of new clean water. This removes emulsifiers and colloids (stabilizers) contained in the mother liquor of the basic grain. The temperature in the reactor ranges from 50 °C to 95 °C and the surface treatment regime of the basic grain of smokeless powder itself consists of four phases. In the first phase, the reactor is heated to the required temperature, followed by the second phase, in which the phlegmatizer is dosed in suspension with water. The third phase is the so-called final delay, in which the phlegmatizer finally penetrates the surface layer of the basic powder grain of smokeless powder. The duration of this phase is longer than 1 hour. In the last phase of the process, the suspension of the phlegmatized grain is cooled, water is separated and the grain is dried.

[0028] The procedure for phlegmatization of the basic smokeless powder grain differs from the procedure for sample 1 in that the basic smokeless powder grain is dried before the actual phlegmatization. After the smokeless powder grain has dried, the phlegmatizer (deterrent) is applied to the smokeless powder grain in the form of a spray of a solution of phlegmatizer and ethyl alcohol. The phlegmatization of the basic grain is carried out in four stages. In the first stage, the dried basic grain of smokeless powder is heated; in the second stage, the basic powder grain of smokeless powder is sprayed with a phlegmatization solution, the spray being applied to the basic powder grain of smokeless powder at temperatures ranging from 50 °C to 95 °C. The third stage is a final delay, during which the substance finally penetrates the surface layer of the basic powder grain of smokeless powder. This stage lasts longer than 1 hour. In the last stage of the process, the phlegmatized powder grain is cooled.

[0029] The results of the analysis of samples 1 and 2 of smokeless powder after phlegmatization according to the invention on a system of sieves are shown in the following table.

[0030] To assess the ballistic properties of both samples, a test in a high-pressure closed bomb calorimeter was used. A bomb calorimeter is a device that is used to measure the increase in pressure at a constant volume. The measurement is graphically displayed using the so-called gamma curve, which is shown in the figure. From the shape of the gamma curve, it is possible to estimate the total energy of the sample and thus predict the likely behaviour of smokeless gunpowder when fired from a real weapon. The figure shows gamma curve graph of sample 1 phlegmatized according to the invention, of sample 2 phlegmatized according to the invention and of a comparative sample of smokeless gunpowder phlegmatized by dibutyl phthalate according to the background art. The graph shows that sample 2 exhibits a higher increase in pressure, while sample 1 shows a slower increase in pressure and overall gamma curve of sample 1 more closely follows the gamma curve of the standard smokeless powder phlegmatized with dibutyl phthalate according to the background art. The results of both samples according to the invention are within the required limits, but the pressure value of sample 2 is already approaching the limit value.

[0031] In a preferred embodiment, the smokeless gunpowder according to the invention is provided with plasticizers from the group consisting of: - citrates, in particular acetyl tributyl citrate, tributyl citrate, triethyl citrate, acetyl triethyl citrate and / or

[0032] - benzoates, in particular benzyl benzoate, diethylene glycol dibenzoate, dipropylene glycol dibenzoate and / or

[0033] - glycerol esters, in particular triacetin, tributyrin.

[0034] In another preferred embodiment, the smokeless gunpowder according to the invention is provided with stabilizers, in particular triphenylamine and / or diphenylamine and / or urea derivatives, in particular centralite and / or acardite, and / or salicylates, in particular benzyl salicylate and / or phenyl salicylate and / or ethylhexyl salicylate, and / or epoxides, in particular epoxy resins and / or fatty acid epoxides and / or aliphatic epoxides and / or magnesium salts.

[0035] In another preferred example of embodiment, the smokeless gunpowder according to the invention is provided with the content of other energetic additives, in particular nitroglycerin and / or pentrite and / or dipentaerythritol hexanitrate and / or tripentaerythritol ++

[0036] +octanitrate and / or trimethylolpropane trinitrate and / or mannitol nitrates and / or erythritol tetranitrate saccharide nitrates and / or inositol hexanitrate.

[0037] Industrial applicability

[0038] The smokeless gunpowder according to the invention can be used as a low-toxic substitute for smokeless gunpowders containing dibutyl phthalate and / or centralite.

Claims

Patent claims1. Smokeless gunpowder for barrel systems, which contains powder grains, wherein the surface layer of each powder grain is provided with a phlegmatizer for retarding the combustion of the surface layer of each powder grain, characterized in that the surface layer of each powder grain contains 1 to 10 % by volume of a phlegmatizer, which is formed by either- sucrose acetate, sucrose benzoate, sucrose acetate butyrate, sucrose octaacetate or sucrose benzoate disaccharide esters or sucrose diacetate hexaisobutyrate or- a combination of sucrose acetate, sucrose benzoate, sucrose acetate butyrate, sucrose octaacetate or sucrose benzoate disaccharide esters or sucrose diacetate hexaisobutyrate with benzyl esters of salicylic acid, especially benzyl salicylate, or- a combination of sucrose acetate, sucrose benzoate, sucrose acetate butyrate, sucrose octaacetate or sucrose benzoate disaccharide esters or sucrose diacetate hexaisobutyrate with phenyl esters of salicylic acid, especially phenyl salicylate, or- a combination of sucrose acetate, sucrose benzoate, sucrose acetate butyrate, sucrose octaacetate or sucrose disaccharide esters sucrose benzoate or sucrose diacetate hexaisobutyrate with compounds from the group of benzoates, especially diethylene glycol dibenzoate or dipropylene glycol dibenzoate.

2. A method of preparation of smokeless gunpowder for barrel systems, which contains powder grains, wherein the surface layer of each powder grain is provided with a phlegmatizer for retarding the combustion of the surface layer of each powder grain, in which a surface treatment is applied to pre-prepared powder grains to slow down the burning of the surface layer of the powder grains, where the surface treatment is carried out either by applying a phlegmatizer to the powder grains in an aqueous environment using pre-prepared powder grainsbefore drying the powder grains, or the surface treatment is carried out by spraying a phlegmatizer solution onto dry powder grains, characterized in that as a phlegmatizer, a substance according to claim 1 is applied to the surface of the powder grains.

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