Combustible propellant cartridge case with an improved temperature resistance.

The present invention relates to combustible propellant charge containers, such as tubes or cartridges, the temperature resistance is improved. At the same time mechanical properties of these containers can be improved.

It is known from DE-PS 27 10 451, on ammunition shells apply one or more coating layers in order to improve the mechanical properties of these sleeves and to reduce the risk of unintentional ignition of the sleeve. However, the coatings described in this patent solve the problem of heat resistance such as sleeves in such cases, where these in hot scoring combustion chambers, such as coming in the cartridge chambers of automatic weapons, are used. There can then be easily self-inflammation - also referred to as cook-off - occur.

Another disadvantage of these known coatings is that they do not burn residue in many cases, especially when in the paint layer inert materials are included. Therefore, the energy balance of the entire system is adversely affected by many known coatings.

There was therefore the object to develop combustible container for propellant powders that are possible at the same temperature resistant and have mechanical property values ​​that are at least equivalent to those of known containers. Furthermore, the container should residue burn and do not adversely affect the energy balance of the entire Abbrandsystems.

In fulfilling this task now were combustible propellant charge container, which are provided with a surface coating, found that are characterized by a coating with a known as an explosive Nitramine embedded in a binder.

The selected nitramines are those which are known as explosives per se, having a detonation velocity over 7400 m / s and when burned, a high normal gas volume, preferably more than 650 l / kg (measured by the CIT method), deliver. They should also detonation points over 200 ° C, preferably above 230 ° C, have. Nitramines that meet these conditions are as cyclotrimethylenetrinitramine (hexogen) or the cyclo tetramethylene tetramine (Oktogene).

Suitable binders are such liquid resins, practicing a desensitizing effect on the Nitra mine off so that they do not detonate, but burn evenly. Furthermore, the resins to harden on exposure to the air. Resins having such properties are known in the art per se. As examples may be mentioned resins based on polyvinyl alcohol, polyvinyl acetal, polybutadiene or polyacrylate.

The proportion of binder in the coating can, depending on the nature of the resins used, 5 to 20 wt .-% vary. Preferably, it is between 10 and 15 wt .-%, particularly when a polyvinyl acetal resin is used as binder.

The thickness of the coatings depends on the particular application and the ingredients used; it may vary between 0.1 and 1.0 mm, it is preferably between 0.2 and 0.5 mm. The application is known per se, optionally dissolved in a suitable solvent, for example by spraying, dipping, rolling or brushing. Application can be carried out either on the not yet processed further sleeve as well as a already provided with the charge and projectile casing. The applied paint may further also contain a known plasticizer.

The inventive coating is always located on the outer surfaces of the container. It can also be attached to the inner wall. In any case, it burns together with the container.

The containers that are coated according to the invention are known to the skilled worker. This is both to combustible tubes or cartridges, as well as to such containers that may be used in place of bag charges. The containers preferably have a central tube for receiving a Anzündverstärkung and are cylindrical or slightly conical.

The coating according to the invention improves the cook-off behavior of the sleeves; they continue to protect the sleeves against humidity and also improves the mechanical properties of the sleeve, such as the tensile strength, impact and wear.

example

There are 85 parts by weight of hexogen together with 12 parts by weight of an acrylate resin, which is stirred under the name PLEXTOL M 600 by the company Röhm, Darmstadt, is commercially available, and 3 parts by weight of dioctyl phthalate in 30 parts by weight Toluene , The paste thus obtained is trowelled on a combustible cartridge case, and adjusted with a calibration tool to a thickness of 0.2 mm. The sleeve obtained after drying the coated film has an auto-ignition temperature of about 240 ° C.

A cartridge manufactured with this sleeve is made during firing in the gun residue around.