Ignition means for propellant powders

Abstract

The present invention describes ignition means for propellant powders. The inventive means are characterized in that said means are free from primary explosives and contain at least one oxidation means, at least one reduction means and at least one binding agent. The invention also relates to the use of said ignition means and to covering foils for propellant powders that are coated with the inventive ignition means.

Description

[0001] The present invention relates to an ignition means for propellant powders, as well as its use.

[0002] Cartridges filled with propellant powders are mainly used in the civil sector, in particular in setting bolt devices or for stunning cattle. The cartridges may be formed of metal or plastics material.

[0003] The propellant powder is normally ignited by a mechanically or electrically initiated reaction of an ignition charge consisting of at least one primary explosive material. A reliable ignition is thereby generally ensured.

[0004] The manufacture and the use of ignition charges containing primary explosive materials are permitted only under special conditions, however, due to safety requirements. In addition there are difficulties in their transportation, since they are classed as dangerous goods, as well as in their storage and handling, which require specially trained and skilled staff.

[0005] An object of the present invention was accordingly to provide an ignition means for propellant powders that does not have these disadvantages.

[0006] This object was achieved according to the invention by the features of the main claim. Preferred embodiments are defined in the subclaims.

[0007] The ignition means according to the invention is essentially concerned with a material for propellant powders that is free of primary explosive and that contains at least one oxidising agent, at least reducing agent and at least one binder.

[0008] The ignition means according to the invention generates, on combustion, particles that ignite the propellant powder.

[0009] By means of the present invention it is therefore possible for the first time reliably to ignite propellant powders without the use of primary explosives.

[0010] The ignition means according to the invention may be used for example for reliable ignition of propellant powders contained in cartridges that are used for example in bolt setting devices. A propellant powder derived from cellulose nitrate may for example be used. The propellant powder may however also consist of components that are used for example in propellant powders that generate low CO content reaction gases (for example so-called SINCO® propellant powders). Reference may be made in this connection to EP 0 809 616 A1. Such cartridges are described for example in DE 198 24 122 A1. The cartridges may be sealed by a foil, for example of aluminium.

[0011] The present invention provides the possibility of treating such sealing foils with the ignition means according to the invention so that, after appropriate initiation, they can act as an ignition means for the propellant powder.

[0012] For this purpose, the foil, for example an aluminium foil, is coated on the inside of the cartridge with the ignition means according to the invention, dried and then applied, for example by adhesion, to the cartridge filled with propellant powder. If the cartridge covering is now rapidly heated externally, for example by an electric discharge, the aluminium can react with the applied components with the formation of self-combusting particles that ignite the propellant powder.

[0013] The invention accordingly also provides coatings that can be applied to foils and that on combustion produce particles that can ignite the propellant powder, as well as the foils coated with the ignition means according to the invention.

[0014] The ignition means according to the invention may consist of the following components or mixtures of these components:

[0015] As binders there may for example be used:

[0016] Cellulose nitrate, cellulose as well as its derivatives such as cellulose acetate, cellulose butyrate, cellulose acetobutyrate, polyvinylbutyrals, polyvinylbutyrates, polynitropolyphenylene or polynitropolyphenyl ether, as well as their mixtures.

[0017] As oxidising agents there may for example be used:

[0018] Nitrates of alkali or alkaline earth elements or of ammonium, for example sodium nitrate, potassium nitrate or ammonium nitrate, perchlorates of alkali or alkaline earth elements or of ammonium, peroxides of alkaline earth elements or of zinc, for example zinc peroxide, or their mixtures.

[0019] As reducing agents there may for example be used:

[0020] Aluminium, titanium, titanium hydride, boron, boron hydride, zirconium, zirconium hydride, graphite or carbon black, as well as their mixtures.

[0021] As stabilisers there may for example be used components known to be effective in the thermal decomposition of nitric acid esters, for example urea derivatives such as Centralite or Akardite.

[0022] As combustion moderators there may for example be used ferrocene and its derivatives or oxidising agents that pass through various oxidation states.

[0023] As further additives there may for example be used energy-rich substances in order to improve the combustion, energy and thermal stability of the applied coating. Such additives are secondary explosives such as for example Octogen, Hexogen, etc..

[0024] In order to identify different formulations it may be advisable to add colourant components.

[0025] In order to improve the smell properties of the combustion gases it is convenient to add odoriferous substances.

[0026] In order to detect unauthorised use it may be expedient to add substances that can be subsequently traced to the manufacturer.

[0027] The amount of the individual components is governed substantially by the respective intended use. The oxidising agent may preferably be used in an amount of 5 to 50 wt. %, the reducing agent preferably in an amount of 5 to 50 wt. % and the binder preferably in an amount of 1 to 40 wt. %. It is particularly preferred to use the oxidising agent in an amount of 10 to 40 wt. %, the reducing agent in an amount of 10 to 40 wt. % and the binder in an amount of 5 to 20 wt. %. The addition of stabilisers, combustion moderators and other additives is also governed by the respective intended use. The nature and the amount can readily be determined.

[0028] The production of the ignition means according to the invention is carried out by methods known per se, for example by mixing the component and applying the latter by coating or also by silk-screen printing.

[0029] The following examples are intended to illustrate the invention in more detail without however restricting the latter.

EXAMPLES

[0030] The following table gives the composition of ignition means according to the invention that may be employed in the form of coatings.

[0031] The coatings may be prepared as follows:

[0032] The binder specified according to the invention is dissolved in a suitable solvent known per se, preferably methyl acetate, and the individual components are added while stirring. The amount of solvent is governed by the laboratory method and the required viscosity. 1 Component Example 1 Example 2 Example 3 Cellulose nitrate 20 wt. % 20 wt. % Cellulose acetate 20 wt. % Zirconium 40 wt. % 30 wt. % Titanium 40 wt. % Potassium nitrate 40 wt. % 30 wt. % Zinc peroxide 50 wt. % 10 wt. %

Claims

1. Ignition means for propellant powders, characterised in that it is free of primary explosive substances and contains at least one oxidising agent, at least one reducing agent and at least one binder.

2. Ignition means for propellant powders according to claim 1, characterised in that, during combustion, it produces particles that ignite the propellant powder.

3. Ignition means for propellant powders according to claim 1 or 2, characterised in that the oxidising agent is selected from nitrates of alkali or alkaline earth elements or of ammonia, perchlorates of alkali or alkaline earth elements or ammonia, peroxides of alkaline earth elements or of zinc or their mixtures, the reducing agent is selected from aluminium, titanium, titanium hydride, boron, boron hydride, zirconium, zirconium hydride, graphite or carbon black or their mixtures, and the binder is selected from cellulose nitrate, cellulose or its derivatives such as cellulose acetate, cellulose butyrate, cellulose acetobutyrate, polyvinylbutyrals, polyvinylbutyrates, polynitropolyphenylene, polynitropolyphenyl ether or their mixtures.

4. Ignition means for propellant powders according to one or more of claims 1 to 3, characterised in that it contains in addition at least one stabiliser, at least one combustion moderator and/or at least one additive for improving combustion, energy or thermal stability.

5. Ignition means for propellant powders according to claim 4, characterised in that as stabiliser there is selected a component proven to be effective in the thermal decomposition of nitric acid esters, from the group comprising urea derivatives or their mixtures, as combustion moderator there is selected an oxidising agent that passes through various oxidation states or ferrocene or its derivatives or mixtures, and as additive for improving combustion, energy or thermal stability there is selected at least one secondary explosive substance.

6. Use of the ignition means according to one or more of claims 1 to 5 for coating propellant powders.

7. Use of the ignition means according to one or more of claims 1 to 5 for coating sealing foils for propellant powders.

8. Use of the ignition means according to one or more of claims 1 to 5 for coating cartridge coverings for propellant powders.

9. Sealing foil for propellant powders, characterised in that it is coated with an ignition means according to one or more of claims 1 to 5.