PROPELLANT CHARGE

Abstract

The invention is directed to a propellant charge for guns, to a combination of a propellant charge and a primer, to a firearms cartridge, and to a method for modifying the surface of a propellant charge.

The propellant charge of the invention comprises multiple propellant grains, wherein an exterior part of part of the propellant grains has been subjected to a surface modification treatment comprising the successive steps of suspending propellant grains in water to prepare a slurry, adding an organic solvent to the propellant grains before, after and/or during the preparation of the slurry, mixing the slurry that comprises water and organic solvent for a period of 120 minutes or less, lowering the concentration of organic solvent, removing organic solvent, and drying the propellant grains to remove water; wherein part of the propellant grains has not been subjected to the surface modification treatment.

Claims

1. A propellant charge for guns, comprising multiple propellant grains, wherein an exterior part of part of the propellant grains has been subjected to a surface modification treatment comprising the successive steps of suspending propellant grains in water to prepare a slurry, adding an organic solvent to the propellant grains before, after and/or during the preparation of the slurry, mixing the slurry that comprises water and organic solvent for a period of 120 minutes or less, lowering the concentration of organic solvent, removing organic solvent, and drying the propellant grains to remove water; wherein part of the propellant grains has not been subjected to the surface modification treatment.

2. The propellant charge for guns of claim 1, wherein the organic solvent is added to the propellant grains before the preparation of the slurry.

3. The propellant charge for guns of claim 1, wherein the organic solvent is added to the propellant grains after the preparation of the slurry.

4. The propellant charge for guns of claim 1, wherein the organic solvent is added to the propellant grains during the preparation of the slurry.

5. The propellant charge for guns of claim 1, wherein the surface modification treatment further comprises removing water and/or organic solvent after mixing the slurry that comprises water and organic solvent for a period of 120 minutes or less and before lowering the concentration of organic solvent.

6. A propellant charge for guns, comprising multiple propellant grains, wherein an exterior part of part of the propellant grains has been subjected to a surface modification treatment comprising the successive steps of wetting propellant grains with water or water vapour, adding an organic solvent to the propellant grains before, after and/or during the wetting of the propellant grains, allowing the wet propellant grains and the organic solvent to interact for a period of 120 minutes or less, lowering the concentration of organic solvent, removing organic solvent, and drying the propellant grains to remove water; wherein part of the propellant grains has not been subjected to the surface modification treatment.

7. The propellant charge for guns of claim 6, wherein the organic solvent is added to the propellant grains before the wetting of the propellant grains.

8. The propellant charge for guns of claim 6, wherein the organic solvent is added to the propellant grains after the wetting of the propellant grains.

9. The propellant charge for guns of claim 6, wherein the organic solvent is added to the propellant grains during the wetting of the propellant grains.

10. The propellant charge for guns of claim 6, wherein the surface modification treatment further comprises removing water and/or organic solvent after allowing the wet propellant grains and the organic solvent to interact for a period of 120 minutes or less, and before lowering the concentration of organic solvent.

11. The propellant charge for guns of claim 1, wherein the propellant grains comprise nitrocellulose.

12. The propellant charge for guns of claim 1, wherein the propellant grains comprise LOVA-propellant.

13. The propellant charge for guns of claim 1, wherein the organic solvent is more volatile than water.

14. The propellant charge for guns of claim 1, wherein the organic solvent comprises one or more selected from methyl acetate, ethyl acetate, isopropyl acetate, isobutyl acetate, t-butyl acetate, isopropyl ether, t-butyl methyl ether, ethyl ether, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl isopropyl ketone, 2-butanone, 3-pentanone, 4-methyl-2-pentanone, 3,3-dimethyl-2-butanone, methyl formate, ethyl formate, propyl formate, acetol, 1,4-dioxane, 2,2-dimethoxy propane, acetonitrile and tetrahydrofuran.

15. The propellant charge for guns of claim 1, wherein the period of time is from 15-120 minutes, preferably 20-100 minutes, such as 30-90 minutes.

16. The propellant charge for guns of claim 1, wherein said lowering of the concentration of organic solvent is performed by adding an additional amount of water.

17. The propellant charge for guns of claim 16, wherein the additional amount of water is 50-700% by weight of the initial amount of water.

18. The propellant charge for guns of claim 16, wherein the additional amount of water is 100-500% by weight of the initial amount of water.

19. The propellant charge for guns of claim 1, wherein the additional amount of water is 175-450% by weight of the initial amount of water.

20. The propellant charge for guns of claim 1, wherein the propellant charge is in the form of a spherical propellant charge or a rifle propellant.

21. A propellant charge and a primer, wherein said propellant charge is the propellant charge of claim 1.

22. The combination of a propellant charge and a primer of claim 21, wherein said primer is present in an amount in the range of 1-10% by total weight of the main propellant charge, preferably 1.5-9%, such as 2-8%.

23. A firearms cartridge comprising the combination of a propellant charge and a primer of claim 21.

24. A method for modifying the surface of propellant grains, wherein said method comprises the successive steps of suspending propellant grains in water to prepare a slurry, adding an organic solvent to the propellant grains before, after and/or during the preparation of the slurry, mixing the slurry that comprises water and organic solvent for a period of 120 minutes or less, lowering the concentration of organic solvent, removing organic solvent, and drying the propellant grains to remove water.

25. The method for modifying the surface of propellant grains of claim 24, wherein the organic solvent is added to the propellant grains before the preparation of the slurry.

26. The method for modifying the surface of propellant grains of claim 24, wherein the organic solvent is added to the propellant grains after the preparation of the slurry.

27. The method for modifying the surface of propellant grains of claim 24, wherein the organic solvent is added to the propellant grains during the preparation of the slurry.

28. The method for modifying the surface of propellant grains of claim 24, wherein the method further comprises removing water and/or organic solvent after mixing the slurry that comprises water and organic solvent for a period of 120 minutes or less and before lowering the concentration of organic solvent.

29. A method for modifying the surface of propellant grains, wherein said method comprises the successive steps of wetting propellant grains with water or water vapour, adding an organic solvent to the propellant grains before, after and/or during the wetting of the propellant grains, allowing the wet propellant grains and the organic solvent to interact for a period of 120 minutes or less, lowering the concentration of organic solvent, removing organic solvent, and drying the propellant grains to remove water.

30. The method for modifying the surface of propellant grains of claim 29, wherein the organic solvent is added to the propellant grains before the wetting of the propellant grains.

31. The method for modifying the surface of propellant grains of claim 29, wherein the organic solvent is added to the propellant grains after the wetting of the propellant grains.

32. The method for modifying the surface of propellant grains of claim 29, wherein the organic solvent is added to the propellant grains during the wetting of the propellant grains.

33. The method for modifying the surface of propellant grains of claim 29, wherein the method further comprises removing water and/or organic solvent after allowing the wet propellant grains and the organic solvent to interact for a period of 120 minutes or less, and before lowering the concentration of organic solvent.

Description

EXAMPLES

Example 1-Spherical propellant grains (10 wt. % of nitroglycerine)

[0108] Spherical propellant grains containing 10 wt. % of nitroglycerine and nitrocellulose and additives were suspended in a 3:1 weight ratio mixture of ethanol and water to prepare a slurry. The slurry was mixed for 30 minutes. The concentration of organic solvent was lowered by evaporation of organic solvent. The spherical propellant grains were then dried in air. The spherical propellant grains before treatment were compared with the surface treated spherical propellant grains.

[0109] Scanning electron microscope images of this comparison are shown in FIG. 1. The picture shown in FIG. 1A shows microscopic images of the spherical propellant grains before treatment, whereas the picture shown in FIG. 1B shows microscopic images of the spherical propellant grains after treatment. Clearly, the treatment has structurally changed the spherical propellant grains.

Example 2-Extruded double base propellant grains (nitroglycerine and diethyleneglycol dinitrate)

[0110] Extruded double base propellant grains containing nitroglycerine and diethylene glycol dinitrate were suspended in a 1:1 weight ratio mixture of acetone and water to prepare a slurry. The slurry was mixed for 30 minutes. The concentration of organic solvent was lowered by evaporation of organic solvent. The spherical propellant grains were then dried in air. The extruded double base propellant grains before treatment were compared with the surface treated extruded double base propellant grains.

[0111] Scanning electron microscope images of this comparison are shown in FIG. 2. The pictures shown in FIGS. 2A and 2B show microscopic images of the extruded double base propellant grains before treatment, whereas the pictures shown in FIGS. 2C and 2D show microscopic images of the extruded double base propellant grains after treatment. Clearly, the treatment has structurally changed the extruded double base propellant grains.

Example 3-Film of material of spherical propellant grains (10 wt. % of nitroglycerine)

[0112] Spherical propellant grains containing 10 wt. % of nitroglycerine and nitrocellulose and additives as used in example 1 were dissolved in acetone. A film of the propellant material was prepared by evaporation of the acetone. This film was used for subsequent treatment.

[0113] Part of the film was submersed in a 1:1 weight ratio mixture of acetone and water for a period of 30 minutes. Thereafter, the film was dried in air.

[0114] Scanning electron microscope images were made showing the boundary line between the untreated part and the treated part of the film, as shown in FIGS. 3A and 3B. Clearly, the treatment has structurally changed the material of the spherical propellant grains. The same structural change is expected to occur on spherical propellant grains that are subjected to the treatment of the invention.

Example 4-Film of material of extruded double base propellant grains (nitroglycerine and diethyleneglycol dinitrate)

[0115] Extruded double base propellant grains containing nitroglycerine and diethylene glycol dinitrate as used in example 2 were dissolved in acetone. A film of the propellant material was prepared by evaporation of the acetone. This film was used for subsequent treatment.

[0116] Part of the film was submersed in a 1:1 weight ratio mixture of acetone and water for a period of 30 minutes. Thereafter, the film was dried in air.

[0117] Scanning electron microscope images were made showing the boundary line between the untreated part and the treated part of the film, as shown in FIG. 4. Clearly, the treatment has structurally changed the material of the extruded double base propellant grains propellant grains. The same structural change is expected to occur on extruded double base propellant grains that are subjected to the treatment of the invention.

Example 5-12.7 mm ammunition with spherical double base

[0118] Temperature dependency of untreated and treated propellant grains was determined by measuring projectile velocity of munition fired from a conventional 12.7 mm caliber barrel weapon as a function of temperature. The munition was filled with double base propellant having a spherical propellant grain geometry. The treated part of the propellant mixture of untreated and treated propellant had been treated with an ethyl acetate-water mixture. The treated part of the propellant mixture of untreated and treated propellant had been treated by suspending propellant grains in water, adding ethyl acetate to the obtained slurry, mixing this slurry for 1 hour, lowering the concentration of ethyl acetate by adding more water, distilling off the ethyl acetate, and drying the treated propellant. FIG. 5 shows the resulting graph in which the projectile velocity in case of the treated propellant grains is clearly less dependent on temperature than the projectile velocity in case of the untreated propellant grains.

Example 6-25 mm ammunition with extruded single perforated single base propellant

[0119] Temperature dependency of untreated and treated propellant grains was determined by measuring projectile velocity of munition fired from a conventional 25 mm caliber barrel weapon as a function of temperature. The munition was filled with extruded single base propellant with a single perforated propellant grain geometry. The treated part of the propellant mixture of untreated and treated propellant had been treated by wetting propellant grains with an ethanol-water mixture during 30 minutes in a rotating drum after which the solvent and the water were removed by drying. FIG. 6 shows the resulting graph in which the projectile velocity in case of the treated propellant grains is clearly less dependent on temperature than the projectile velocity in case of the untreated propellant grains.