EP1438274A2

EP1438274A2 - Production of water-free nitrocellulose and explosive substances that have a spheroidal shape

Info

Publication number: EP1438274A2
Application number: EP02782986A
Authority: EP
Inventors: Gerhard Huber
Original assignee: Bowas AG fuer Industrieplanung
Current assignee: Bowas AG fuer Industrieplanung
Priority date: 2001-10-24
Filing date: 2002-10-23
Publication date: 2004-07-21
Also published as: WO2003035581A2; AU2002346869A1; ZA200402643B; US20050000610A1; KR20040060942A; WO2003035581A3; CN1703385A; DE10152396A1

Abstract

The invention relates to a method for producing shaped explosive substances, especially a propelling charge substrate, such as for example a spheroidal propellant charge powder made of a stabilized explosive substance. Said stabilized explosive substance is first dissolved in a solvent, the stabilized substance is removed from the mixture and particles are shaped from the resulting mixture. The invention further relates to a method for producing a varnish made of a substantially water-free explosive substance.

Description

Manufacture of anhydrous nitrocellulose and explosives in spheroidal form

description

The invention relates to a process for the production of shaped nitrocellulose and explosives and fuels according to the preamble of claim 1, a process for the production of an essentially water-free explosive lacquer or an explosive lacquer with a defined water content according to the preamble of claim 8 an explosive paint according to the preamble of claim 10, and a nitrocellulose paint according to the preamble of claim 11.

In the context of this invention, the term “explosives” includes explosive and / or explosive, in particular solid, liquid and gelatinous substances and

To understand mixtures of substances that are used for use as explosives, fuels, detonators or as pyrotechnic phrases or are used for their production.

Explosives are used for numerous applications, particularly in the ammunition sector. As a rule, it is for both efficient and effective

Application necessary that the explosives have a certain geometry, for example spherical. In this way it is possible to fill explosive substances, for example as propellant charges, into projectile casings. In order to ensure homogeneous and uniform combustion of the explosives, a defined structure and a defined geometry thereof are required, the latter being achievable, for example, by the explosives being present in uniform sizes, preferably as spherical or spheroidal particles. Nitrocellulose can be both the explosive described above and a raw material for paint production. Spherical nitrocellulose as a raw material for paint production offers the advantages that it is in this form is also desensitized without moistening agent, is easy to handle and additives may already have been incorporated.

One application in the explosives area is the production of spheroidal propellant powder. So far, the shape has been achieved in that water damp

Dissolved nitrocellulose in ethyl acetate and then this organic phase was distributed in an aqueous phase by intensive stirring. In this process, particles with very irregular sizes are always formed. In addition, particle formation by coalescence very easily occurs again after particle formation, since the lacquer for this type of particle formation may only have a low viscosity, which in turn promotes coalescence. After the particle formation, the solvent is evaporated with stirring, the nitrocellulose remaining in the form of rounded particles in the aqueous phase.

These can be separated from the aqueous phase, for example by filtering.

A disadvantage of this process is that the spheroidal particles formed have a very wide size distribution. In some cases, the proportion of the size range that can be used for an application is only 1/3 of the total mass;

Sieving operations must be separated.

Another method for producing spherical nitrocellulose particles uses an underwater granulator for the formation of the particles. The organic phase is pressed into the aqueous phase through a perforated disk, the strands emerging from the holes in the perforated disk being broken up into particles by a rotating knife on the outlet side. Classification of the spheres formed is also necessary in this method. Further disadvantages of this process are that the organic phase for use in the underwater pelletizer has to have such a high consistency that the cylindrical particles which are formed no longer round in the normal stirring process. They must therefore be conveyed through long pipelines with a small cross-section, the rounding taking place through intensive contact with the pipe wall.

High throughput rates of the device require high rotational speeds of the knife. With the speed of the rotating knife, the hydraulic shear forces increase, which very quickly leads to a reduction in quality due to another cause uncontrolled comminution of the particles. The speed of the cutting knife, which is very limited as a result, considerably limits the performance of the device.

As in the above process, the particles are hardened by removing the solvent.

Due to the manufacturing process, the particles produced by both processes still contain undefined quantities of dispersed water, which causes an undefined porosity in the finished grain. However, this is a decisive quality feature of the product, since the porosity has a decisive influence on the burn-up of the product. Depending on

Use may be desired from minimal porosities to high porosities, the degree of which must, however, be precisely defined. Therefore, in the past, the water content was adjusted by dewatering before the particles hardened. This was usually done by taking advantage of the osmotic effect created by the addition of sodium sulfate to the aqueous dispersion. The extent of the drainage was controlled via the salt concentration, the exposure time and the temperature. This drainage process is very difficult to control and leads to unsatisfactory results. Another disadvantage here is that salt residues inevitably remain, at least on the particles. This means that washing steps are required in the process. Remaining salt residues can have a desensitizing effect on the effectiveness of the explosive.

In addition, the amount of sodium sulfalt required for water removal in particular has considerable environmental disadvantages.

Thus, it has so far not been possible with the conventional methods to produce explosive particles, in particular from nitrocellulose, with a spherical geometry with a uniform size, which have a defined porosity and are largely free of pores, water and salt, in a simple and cost-effective manner.

The object of the invention is accordingly to provide a method and a substance for the production of shaped explosives, by means of which the aforementioned disadvantages, in particular porosity, water and salt content, inconsistent grain size and the environmentally relevant aspects are avoided. This object is achieved in each case by a method according to patent claims 1 and 8, by using an explosive lacquer according to patent claim 10 and by a nitrocellulose / explosive lacquer according to patent claim 11.

The process for the production of shaped explosives, in particular

According to the invention, propellant charge powder, such as spheroidal propellant charge powder, made from an explosive, in particular desensitized with water, has the following steps:

- dissolving the desensitized explosive in a solvent;

Removing the desensitizing substance, in particular water, from the mixture; Shapes of explosive particles; and collecting the explosive particles.

An essential point of the invention is that by removing the desensitizing substance, in particular water, from the mixture, it is possible to form the explosive particles without having to fear inclusion of a desensitizing substance. Water, but also salt, as well as other organic or inorganic inert or inert substances, such as, for example, alcohol or plasticizers, are to be understood as a desensitizing substance.

According to a preferred embodiment of the invention, the desensitizing substance, in particular water, is removed by means of azeotropic distillation. This allows the water to be removed from the explosive both efficiently and effectively and safely, particularly with the aid of pervaporation / vapor permeation.

According to a development of the invention, the solvent is returned to the explosive during and / or after the distillation. In this way it is possible to produce an explosive varnish with a predefined viscosity, the viscosity being adjustable on the one hand by the type and / or amount of the solvent, and also on the basis of auxiliaries. Suitable auxiliaries here are, for example, surface-active substances, wetting agents or release agents. If the desensitizing substance is a solid, a salt or another substance which is difficult to distill, it is provided according to the invention that it is extracted with suitable solvents. Solid phase extraction or precipitation, for example, is also possible according to the invention, provided that this is compatible with the type of explosive, in particular its density and solubility. Sublimation is also possible, provided that this can be done safely.

According to a further embodiment of the invention, the shaping of nitrocellulose and / or explosive particles is carried out or initiated by means of jet cutting, one jet, preferably a full jet, of an explosive-solvent mixture or one

Explosive-solvent solution, in particular an explosive lacquer, is divided by means of a separating device into jet sections with a defined and / or adjustable length, which fall into a, preferably moving, fluid in which the explosive-solvent mixture, in particular lacquer, is poor and / or essentially insoluble.

This process is excellently suited for the production of spheroidal particles with approximately the same grain size for processing explosive-solvent mixtures.

In the production of the spheroidal particles, the organic phase of the fluid to be processed, from which the particles are to be produced, is pressed out of a nozzle at high speed in the form of a full jet. Directly below the nozzle is a rotating cutting tool, which consists of short, preferably held in a socket outwardly facing wires, which divides the fluid jet into cylindrical segments. When falling further, spherical particles form from these segments due to the surface tension of the fluid, and these particles are collected in a solvent, in particular in water.

The size of the particles produced is dependent on the nozzle diameter

Volume flow through the nozzle, the number of cutting wires and the rotational speed of the cutting tool adjustable and is according to the invention in Range from 0.1 mm to 10 mm, preferably in the range from 0.2 mm to 2 mm and particularly preferably in the range from 0.5 mm to 1.5 mm.

One of the main advantages of the invention is that it is ensured by means of jet cutting that only particles with a desired size that can be adjusted by means of the aforementioned parameters can be produced, and also that the explosive particles produced essentially only contain explosive and solvent, however contain no or a precisely defined amount of a desensitizing substance. In the following, the advantages of the jet cutting process are first discussed:

Due to the inclination of the cutting plane to the beam axis, largely cylindrical particles that are already close to the spherical shape can be cut from the moving beam.

Furthermore, the cutting device runs in the air. This means that very high cutting frequencies and high throughputs are possible.

In contrast to the underwater pelletizer, the cutting tool has no contact with the outlet opening.

For the rest, only a simple and inexpensive construction is necessary to carry out the jet cutting process.

Taking advantage of the jet cutting method and using correspondingly coordinated parameters, losses due to an inhomogeneous particle size distribution can thus be reduced to less than 3%, in particular to less than 2%, of the explosive-solvent mixture used.

If it is a sufficiently viscous explosive that can be handled safely without a solvent, it can also be used directly for the jet cutting process. Another important advantage of the invention is that explosive particles with a defined porosity can be produced, the degree of porosity being set, for example, by the introduction of suitable substances, in particular water, into the explosive lacquer. For this purpose, substances are preferably used which diffuse out of the explosive particle or can be detached and thus leave a cavity in the explosive particle. It is also possible to use salts or similarly inert substances which remain in solid form in the explosive particle.

By means of such non-explosive residues and / or holes or pores in the explosive particles, it is advantageously possible to influence the speed and temperature of the erosion and thus the speed of detonation of the explosive.

Accordingly, it is also possible to produce multilayer explosive particles, with different explosive varnishes being used for this purpose in jet cutting through a central nozzle and through one or more ring-shaped nozzles. In this way it is possible, for example, to produce an explosive with an inwardly increasing rate of combustion, for which purpose for example an outer layer contains a corresponding amount of a desensitizing substance or a more slowly burning explosive.

According to a development of the present invention, water-containing nitrocellulose is used as the desensitizing explosive and ethyl acetate is used as the solvent. This explosive-solvent system is ideal for the production of spherical, water and salt-free nitrocellulose particles, which are particularly suitable for the production of spheroidal propellant powder.

Furthermore, the object of the invention is achieved by a method for producing an essentially water-free explosive lacquer or an explosive lacquer with a defined water content, in particular nitrocellulose lacquers, from an explosive which has been desensitized, in particular with water, the method following the following Steps comprises:

Dissolving the desensitizing explosive in a solvent; Removal of the desensitizing substance, in particular water, from the mixture by means of azeotropic distillation with a defined water content; and

Setting a predetermined viscosity of the explosive paint.

The main advantage of this aspect of the invention is that an essentially water-free explosive varnish is suitable for the production of water-free and also salt-free explosive particles, since, according to the method, these consist of a matrix from which the particles are produced before the use of the explosive lacquer. have been removed.

According to a further development, the solvent for setting a predefined viscosity is returned to the explosive before and / or after the distillation. According to the invention, auxiliaries such as, in particular, surface-active substances, wetting agents, release agents and agents for adjusting the viscosity can also be used to adjust the viscosity.

The use of wetting and / or release agents makes it possible, for example, to optimally match the explosive varnish to the materials with which it comes into contact during the manufacturing process, so that, for example, contamination caused by the explosive sticking to the apparatus and equipment used is minimized is or is completely omitted. Due to the inherent energy content of an explosive, such measures contribute to handling and operational safety in the manufacture of explosives.

Furthermore, the object is achieved by using an essentially water-free explosive lacquer, in particular a nitrocellulose lacquer, for producing shaped, in particular spherical or spheroidal, explosive substances.

In addition, the object of the invention is achieved by a nitrocellulose lacquer which consists of at least nitrocellulose and a solvent, the nitrocellulose lacquer being essentially water-free. According to the invention, the nitrocellulose lacquer has a viscosity which makes it possible, in particular by means of the jet cutting method, to have particles with a predefinable particle size in the range from 0.1 mm to 10 mm, preferably in the range from 0.2 mm to 2 mm and particularly preferably to form in the range of 0.5 mm to 1.0 mm.

5

In this way it is possible to produce a particularly preferred particle size.

As already mentioned above, the nitrocellulose lacquer preferably has auxiliaries, in particular surface-active substances, wetting agents or release agents, and agents for adjusting the viscosity.

According to a further development, the nitrocellulose lacquer is essentially salt-free.

Further embodiments of the invention result from the subclaims. 15 The invention is explained in more detail below on the basis of the exemplary embodiments.

example 1

A kilogram of nitrocellulose (= ceilulose nitrate with an N content of approx. 12.5%), which in addition to 700 grams of nitrocellulose contains approx. 300 grams of water, is in one liter

20 ethyl acetate dissolved, the water fraction being partly dissolved and partly dispersed.

The mixture is distilled azeotropically, the distilled azeotrope being dewatered and the ethyl acetate being continuously returned to the distillation. After the water has been completely removed from the nitrocellulose-ethyl acetate solution, it is subjected to a jet cutting process using cutting wires with a thickness of 0.05 mm

25 fed. The resulting particles are collected in water, this one

Can contain release agents and is kept in motion by means of a stirrer. After the complete batch of nitrocellulose has gone through the jet cutting process, the water-particle mixture is concentrated with simultaneous application of a vacuum until the particles are present in the water essentially without solvent.

30 Due to the hydrophobicity of the particles, there is no fear of water diffusing into the particles. Following the concentration by distillation, the particles formed are filtered out of the particle-water mixture. The particle size obtained is 0.8 mm in diameter. The yield is 98.5% based on the nitrocellulose used. Example 2

One kilogram of nitrocellulose (= cellulose nitrate with an N content of approx. 13.2%), which contains approx. 300 grams of water in addition to 700 grams of nitrocellulose, is dissolved in one liter of ethyl acetate, the water fraction being partly dissolved and partly dispersed ,

The mixture is distilled azeotropically, the distilled azeotrope being dewatered and the ethyl acetate being continuously returned to the distillation. After the water has been completely removed from the nitrocellulose-ethyl acetate solution, 100 g of metriol trinitrate dissolved in 200 g of ethyl acetate are added to the mixture. The resulting explosive varnish is then fed to the jet cutting process as described above and processed further.

Example 3

One kilogram of nitrocellulose (= cellulose nitrate with an N content of approx. 12.2%), which in addition to 700 grams of nitrocellulose contains approx. 300 grams of water in one liter

Ethyl acetate dissolved, the water fraction being partly dissolved and partly dispersed.

The mixture is distilled azeotropically, the distilled azeotrope being dewatered and the ethyl acetate being continuously returned to the distillation. After the water has been completely removed from the nitrocellulose-ethyl acetate solution, 20 g of dibutyl phthalate dissolved in 200 g of ethyl acetate are added to the mixture. The resulting nitrocellulose varnish is then fed to the jet cutting process and further processed as previously described.

At this point, it should be pointed out that all the parts described above are seen on their own and in any combination are claimed as essential to the invention. Modifications to this are familiar to the person skilled in the art.

Claims

PATENT CLAIMS

1. Process for the production of shaped nitrocellulose and explosive and

Fuels, in particular propellant charge substrate, such as spheroidal propellant charge powder, from an explosive, in particular water-phlegmatized, g e k e n n e e i c h n e t d u r c h the following steps:

Dissolving the desensitized explosive in a solvent; Removing the desensitizing substance, in particular water, from the mixture; Shapes of explosive particles; and collecting the explosive particles.

Method according to one of the preceding claims, d a d u rc h g e ke n n z e i c h n e t, that the removal of the desensitizing substance is carried out by means of azeotropic distillation.

3. The method according to any one of the preceding claims, in particular according to claim

2, because of the fact that the solvent is returned to the explosive during and / or after the distillation to produce an explosive varnish with a predefined viscosity.

4. The method according to any one of the preceding claims, characterized in that the shaping of the explosive particles is carried out or initiated by means of jet cutting, a jet of an explosive-solvent mixture or an explosive-solvent solution, in particular explosive lacquers , by means of a separating device into beam sections with a defined and / or adjustable length is divided, which fall into a, preferably moving, fluid in which the explosive paint is poor and / or essentially insoluble.

5. The method according to any one of the preceding claims, d a d u r c h g e ke n n z e i c h n e t

Explosive particles are produced with a defined porosity, the degree of porosity being set in the explosive lacquer by entering and / or remaining phlegmatizing substances, in particular water.

6. The method according to any one of the preceding claims, characterized in that ß explosive particles with a defined grain size are produced in the range from 0.1 mm to 10 mm, preferably in the range from 0.2 mm to 2 mm and particularly preferably in Range is 0.5 mm to 1.0 mm.

7. The method according to any one of the preceding claims, d a d u r c h g e ke n n z e i c h n e t, d a ß is used as a desensitized explosive, water-containing nitrocellulose and as a solvent ethyl acetate.

8. Method for producing an explosive varnish with a defined water content, in particular nitrocellulose varnish, from an explosive, in particular with water, desensitized, g e ke n n z e i c h n et d u r c h the following steps:

Dissolving the desensitized explosive in a solvent; Removal of the desensitizing substance, in particular water, from the mixture by means of azeotropic distillation with adjustment to a defined water content; and setting a predetermined viscosity of the explosive paint.

Method according to claim 8, characterized in that ß the solvent is returned to the explosive during and / or after distillation to set a predefined viscosity.

10. Use of an explosive lacquer with a defined water content, in particular nitrocellulose lacquer for the production of shaped, in particular spherical or spheroidal, explosives.

11. Nitrocellulose lacquer, consisting of at least nitrocellulose and a solvent, so that the nitrocellulose lacquer has a defined water content.

12. Nitrocellulose paint according to claim 11, characterized in that the nitrocellulose paint is essentially anhydrous.

13. Nitrocellulose lacquer according to one of claims 11 or 12, characterized by the fact that the nitrocellulose lacquer has a viscosity which makes it possible, in particular by means of the jet cutting method, to have particles with a predefinable grain size in the range of 0.1 mm to 10 mm, preferably in the range from 0.2 mm to 2 mm and particularly preferably in the range from 0.5 mm to 1.0 mm.

14. Nitrocellulose lacquer according to one of the preceding claims 11, 12 or 13, d a d u rc h g e ke n n z e i c h n et, d a ß the nitrocellulose lacquer auxiliaries, in particular surface-active substances,

Contains wetting agents or release agents as well as viscosity adjusting agents.

15. Nitrocellulose lacquer according to one of the preceding claims 11 to 14, d a d u r c h g e ke n n z e i c h n e t, that the nitrocellulose lacquer is essentially salt-free.