RU2093500C1 - Method of preparing powder mass in pyroxylin powder production - Google Patents

Abstract

FIELD: powder production. SUBSTANCE: method consists in mixing powder components in water at temperature exceeding lower critical temperature of mixing syntanol (used as solvent and plasticizer) with water. EFFECT: facilitated powder mass preparation. 2 tbl

Description

 The invention relates to the production of gunpowder by pyroxylin technology.

 The main principle for the manufacture of pyroxylin powders is to displace pyroxylin with a plasticizer solvent, plasticize it to form a plastic mass, ready to be molded, to manufacture powder elements from it, and then to remove the plasticizer solvent from them.

 Displacement of the powder mass, consisting of pyroxylin, a chemical stabilizer. the resistance of diphenylamine and a plasticizer solvent, is carried out in special mixers by mechanical grinding, during which pyroxylin swells and partially plasticizes, which ends upon pressing and the formation of finished powder elements.

As a plasticizer solvent, a mixture of ethanol and diethyl ether, which are flammable, is traditionally used. The use of the specified plasticizer solvent provides for the preliminary dehydration of pyroxylin, since the water present in it after the stabilization phase prevents swelling and, for the plasticization process to be successful, its amount must be reduced to a certain limit (no more than 4%). To this end, pyroxylin is dehydrated with alcohol, which displaces water. [Horst A.G. Gunpowder and explosives, M. Engineering, 1972. 152-153 prototype]
In addition to the need for preliminary dehydration of pyroxylin, the disadvantage of mixing the components by mechanical grinding is the increased fire and explosion hazard of the process and the difficulty of uniform distribution of ingredients throughout the mass of cellulose nitrates, which ultimately affects the output characteristics of the finished product.

 The aim of the present invention is to increase the safety of the process of displacement and plasticization of the powder mass and improving the quality of the finished product.

 This goal is achieved by using the synthetic higher fatty alcohols and ethylene oxide, known under the commercial name "syntanol" as the pyroxylin, a hardly-volatile plasticizer pyroxylin, to be removed.

 Synthols are characterized by low volatility, high flash points and autoignition, they are produced by the domestic chemical industry in large tonnage, are low- or practically non-toxic (class 3 according to GOST 1271.007), belong to the group of biologically “soft” products (biodegradability from 67 to 85% depending from the brand).

 The main advantage of syntanols in comparison with other plasticizer solvents used, which are characterized by unlimited solubility in water, is the presence of a lower critical displacement temperature, i.e., limited phase compatibility with water, consisting in the fact that depending on the concentration and temperature of their mixture with water are either homogeneous and isotropic solutions, or heterogeneous systems. In the latter case, syntanols are easily adsorbed by nitrocellulose fibers, almost completely removed from water. It is this property of them that formed the basis of a new method of component displacement, carried out by the method of cooking. It consists in the fact that the calculated amount of syntanol is dissolved in water, then the temperature of the solution is raised and syntanol is transferred to a finely dispersed emulsion, nitrocellulose is added and the mass is maintained until all syntanol is adsorbed by the fibers. After some exposure, the mass is separated from water to a residual moisture content of about 45%, after which it is almost ready for processing into powder elements.

 Thus, the use of syntanol allows you to process undehydrated pyroxylin, and mixing the components by cooking more evenly distribute it throughout the mass of pyroxylin, which contributes to better plasticization compared to mechanical mixing of the components.

 As already noted, anhydrous pyroxylin taken from the stabilization phase is used for mixing. Since the mixing is carried out in an aqueous medium, the moisture content of the initial pyroxylin does not affect the process and is determined only by the conditions for its stabilization.

 The amount of syntanol synthesizing plasticizer solvent is regulated on the one hand by the quality of plasticization and, on the other hand, syntanol soaking time. Experimental data indicate that the optimal amount of syntanol is 60-65 mass. in relation to the dry weight of pyroxylin. When you enter syntanol less than 60 mass. the plasticization process significantly slows down, and with an increase in its number in excess of 65 mass. the time of soaking increases and, therefore, the complexity of the process.

 Chemical stabilizer resistance diphenylamine is introduced into the mass in the form of a solution in syntanol. Its quantity corresponds to that which is introduced using standard technology.

The amount of water in which the cooking is carried out, is 5 ^o C10 parts in relation to 1 part of pyroxylin. Reducing the module below 5 leads to a sharp deterioration in the process of mixing the mass, and an increase in excess of 10 to the additional irrational water flow while reducing the utilization of equipment.

 Testing of the method proposed by the authors was carried out in the manufacture of lamellar pyroxylin powder of the Sokol type.

 Example. Description of the manufacturing process of the samples.

For mixing was used pyroxylin water humidity of 28 ^o C45 mass. with a nitrogen content of at least 298.5 ml NO / g, taken directly from the stabilization phase without any prior dehydration.

Chemical stabilizer resistance diphenylamine was introduced in the form of a solution in syntanol in an amount of 1.0 ^o C2.0 mass. in relation to the dry weight of pyroxylin.

As a plasticizer solvent, syntanols of grades DT-308 (TU 6-14-19-248-87) and ALM-10 (TU 7-14-864-86) were used. Sintanol brand ALM-10, at room temperature representing a pasty product, was preheated to 50-55 ^o C, translating into a viscous-flowing state. The amount of syntanol introduced was 60-65 mass. in relation to dry weight of pyroxylin.

Mixing was carried out as follows. The calculated amount of syntanol was introduced into the water with stirring (pyroxylin module 5 ^° C10), having previously selected a certain amount to dissolve diphenylamine, and the solution temperature was adjusted to 80-85 ^° C. At this temperature, the synthesis of syntanol from water in the form of a thin emulsion as evidenced by turbidity solutions in the entire volume. To the resulting emulsion, pyroxylin and a solution of diphenylamine in syntanol were added portionwise with constant stirring. At the end of the dosage, the resulting mass is stirred for another 30 minutes at a temperature of 80-90 ^o C, after which it is separated from water to a residual moisture content of up to 45 wt. and served on the phase of formation of the powder elements.

Elements in the form of plates were formed from a web made on heated horizontal rollers with a diameter of 155 mm and a length of 320 mm at a rotation frequency of 16 min ^-1 . The temperature of the rollers was maintained within the range of 45-55 ^o C. The size of the gap between the rollers was selected so that the thickness of the finished web was 0.12 ^o C0.16 mm.

The relationship between the moisture content of the initial mass and the conditions of its processing was studied (see table. 1)
Thus, the results presented in table 1 indicate that the moisture content of the finished fabric is practically independent of the moisture content of the initial mass and varies within fairly narrow limits: 0.783 $\genfrac{}{}{0ex}{}{\text{+0.047}}{\text{-0.073}}$ wt.

 The fabric made was cut into plates of a given shape and processed according to the regimes of standard manufacturing techniques for porous pyroxylian powder of the Sokol brand.

 Table 2 shows the characteristics of the obtained samples and the base sample (example 4).

 The data presented in table 2 indicate that the samples of gunpowder made by mixing the mass of undehydrated pyroxylin by cooking (examples 1, 2, 3) in terms of basic physicochemical parameters and ballistic characteristics are at the level of standard pyroxylin powder of the Sokol brand (example 4), made from dehydrated raw materials using potassium nitrate as a porophore, and in terms of the mass of the powder charge and the average flight speed of the shot projectile surpass it.

 Thus, the method developed by the authors for mixing components by cooking allows to obtain pyroxylin powder from unhydrated raw materials, bypassing the alcohol dehydration phase, which reduces the cost of the process and makes it environmentally cleaner. The use of refractory syntanol as a plasticizer solvent completely eliminates the need for use in the production of volatile substances. All this as a whole leads to a decrease in the complexity of production, its fire and explosion hazard.

 The quality of the finished product obtained by mixing the components by the cooking method provides the specified ballistic characteristics when weighed, 20-25% less than on a standard (base) product.

Claims (1)

 A method of preparing a powder mass in the manufacture of pyroxylin powders, comprising mixing pyroxylin, a stabilizer of chemical resistance of diphenylamine and a plasticizer solvent, characterized in that syntanol is used as a plasticizer solvent, and the powder mass is prepared by mixing the components in water at a temperature above the lower critical temperature mixing syntanol with water.

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