RU2651160C1 - Method of drying gas-generating compositions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: drying of composite powder based on polyvinyl butyral is carried out in three stages by supplying heated air in several stages with subsequent cooling of the product. The first stage is carried out at a temperature of 40±2°C for 13-14 hours, the second stage - at a temperature of 50±2°C for 13-14 hours and the third stage - at a temperature of 60±2°C for 3-4 hours.

EFFECT: reduction of the mass fraction of alcohol, the possibility to avoid sticking of elements of the gas-generating composition with increasing the safety of the drying operation.

1 dwg, 1 tbl

Description

The invention relates to the field of production of gas generating compositions, in particular composite powders, which can be used in squibs for various purposes.

The technology for producing gas generating compositions includes the phases of mixing the components using ethyl alcohol or other volatile thermodynamically active plasticizer as a solvent, forming and cutting the cords to granules of a certain size, drying the granules with heated air and cooling them to room temperature.

Known methods of drying granules of spherical powder [1, 2], which describe the removal of moisture in a "fluidized" layer by supplying air heated to temperatures of 95-105 ° C and 88-98 ° C, respectively. The disadvantage of drying methods is the high temperature of the supplied air.

As a prototype, the method of drying pyroxylin powders of the following component composition was selected: cellulose nitrate (91-97 wt.%), Diphenylamine (1.0 wt.%), Residual alcohol-ether solvent (0.5-5.0 wt.%) And moisture (0.8-1.1 wt.%). Drying of these powders is carried out in table dryers, which consist of 1-3 sections [3]. From the bottom, through the air duct, heated air is supplied to the table drying through a heater, which, passing through a layer of gunpowder, removes moisture. Drying is carried out in two stages: the first at a supply air temperature of 75 ° C, the second at a supply air temperature of 55 ° C. Drying time depends on the height of the layer of loaded gunpowder, humidity, and the geometric dimensions of the granules (grade of gunpowder) and ranges from 40 to 200 hours.

The disadvantages of the method:

- sticking together elements of the gas generating composition;

- increased fire hazard of the process of removing alcohol.

The technical result is the elimination of adhesion of the elements of the gas generating composition and increasing the safety of the drying operation.

This technical result is achieved in that the method of drying the composite gunpowder based on polyvinyl butyral, used as a gas-generating composition in the squib cartridge, including supplying heated air in several stages, drying and cooling the product, differs in that drying is carried out in three stages: the first stage is temperature 40 ± 2 ° C for 13-14 hours, the second stage - at a temperature of 50 ± 2 ° C for 13-14 hours and the third stage - at a temperature of 60 ± 2 ° C for 3-4 hours.

The drying method was tested on such compositions: 79.1-80.8 wt.% The oxidizing agent - 1,3,5-trinitro-1,3,5-triazacyclohexane or 1,3,5,7-tetranitro-1,3, 5.7-tetraazacyclooctane, 13.7-14.4 wt.% Binder - polyvinyl butyral, 5.9-7.1 wt.% Technological additives dibutyl phthalate, oleic acid, paraffin, zinc stearate and soot.

Examples of the method of drying composite powders are shown in table 1.

The first stage of drying at a temperature of 40 ± 2 ° C allows the volatile solvent to be removed from the surface of the granules without sticking together. As the air temperature rises in the second and third stages, the solvent is removed from the volume of the granules. The kinetics of ethanol removal is shown on the skull.

From the data of table 1 it can be seen that an increase in the drying temperature in the first stage to 60 ± 2 ° C (Project No. 4) leads to adhesion of the elements of the gas-generating composition. Increasing the drying time is not advisable, because increases labor costs without further reducing the alcohol content in the granules (Ex. No. 5 and see drawing). The proposed drying method (Project No. 1, 2, 3) allows to reduce the mass fraction of alcohol to 0.055%, and also to avoid sticking together of elements of the gas-generating composition.

LITERATURE

1. Patent RU 2497792 Method for pre-drying spherical powder C06B 21/00, publ. 11/10/2013.

2. Patent RU 2516516 A method for producing spherical powder C06B 21/00, publ. 05/20/2014.

3. V.I. Hindich Technology of pyroxylin powders. T. 2. Kazan: Tatars. gas. - journal. Publishing House, 1995, 391 pp.

4. The procedure for the production of pilot batches of varnish powder PS-690 / 4.23, PSf-670 / 3.85, Sunar-SF, SS-690/410, "Cowboy-500", "Temp-extra" , “Cowboy-370”, “Sapsan-S”, SG-620 / 4.0, PGS-600, PGS-690, RTP 8-91. FKP "GosNIIHP" .3

Claims (1)

A method of drying a composite powder based on polyvinyl butyral used as a gas-generating composition in a squib cartridge, comprising supplying heated air in several stages, drying and cooling the product, characterized in that drying is carried out in three stages: the first stage at a temperature of 40 ± 2 ° C within 13-14 hours, the second stage - at a temperature of 50 ± 2 ° C for 13-14 hours and the third stage - at a temperature of 60 ± 2 ° C for 3-4 hours.

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