JPH07267770A - Solid propellant and its production - Google Patents

Abstract

PURPOSE:To enhance packing properties of an oxidizing agent, to improve the specific impulse of the propellant and to widen the scope of application to solid propellants of ammonium nitrate (an oxidizing agent) by forming a powder of the oxidizing agent to be used as a component of the propellent into a prescribed shape. CONSTITUTION:In this propellant, a powdery oxidizing agent is formed into pellets having a prescribed shape prior to mixing it into a propellant base material and thereby, the specific surface area per unit weight of the oxidizing agent is minimized to improve the mixing properties of the oxidizing agent at the time of producing the propellant and also, to enhance the packing properties of the oxidizing agent and further, to improve the specific impulse of the propellant. As for the shape of the pellet, a spherical shape is preferred, but the design of the shape can be changed depending on the purpose to any shape such as cylindrical or prismatic shape, etc., without any specific limitation. As for the size of the pellet, the length of the pellet in its longest direction is preferably within the range of about 1 to 10mm. The compression or wet pelletizing, etc., can be used for this powder forming and the specific gravity of the pellet thus formed is preferably >=95% of the true specific gravity. As for the solid propellants to which this oxidizing agent is appropriately applied, the agent is effectively used for the composite solid propellants. Particularly, since ammonium nitrate has hygroscopic properties, its mixing properties are enhanced by subjecting it to powder forming into a prescribed shape.

Description

Detailed Description of the Invention

[0001]

This invention relates to solid propellants. More specifically, the present invention relates to a solid propellant in which the mixing of the oxidizer into the propellant is improved by using a powder-molded oxidizer, which is molded into a predetermined shape, and a method for producing the same.

[0002]

2. Description of the Related Art Solid propellants have advantages over liquid fuels in that they can be stored for a long period of time and can be launched immediately. Liquid propellants are also used in military rockets, missiles, and space applications. It is used as an auxiliary fuel for fuel. The solid propellant is a hybrid base composite solid propellant formed by mixing each component with an oxidizer and fuel, and a double base system that is a pyrotechnic powder that uses nitroglycerin and nitrocellulose as the main components and a non-volatile solvent Broadly divided into solid propellants.

On the other hand, ammonium perchlorate, nitramine and ammonium nitrate are used as oxidizers for composite solid propellants. Among them, ammonium perchlorate is most preferable as an oxidizing agent for a propellant in terms of oxygen content, and is mainly used as an oxidizing agent for a propellant. However, the use of ammonium perchlorate is expected to be limited in the future in terms of environment, by generating hydrogen chloride as a combustion decomposition product.

For this reason, research on propellants using nitramine and ammonium nitrate has been conducted, and attention has particularly been paid to research on propellants using ammonium nitrate in terms of price.

[0005]

A propellant using ammonium nitrate as an oxidizer is a preferable propellant for the environment because it does not contain hydrogen chloride in exhaust smoke (combustion decomposition products), but it should be solved mainly in use. Two challenges remain. 1) Improvement of specific thrust 2) Manufacturing problem It is theoretically clear that the specific thrust of 1) is lower than the difference in the oxygen content in one molecule compared to the propellant using ammonium perchlorate as an oxidant. However, specific impulse is the basic performance of propellants, and research to improve it is energetically underway.
For example, to impart energy to the fuel components used in propellants, or small amounts of ammonium perchlorate,
For example, using nitramine together. The problem in the production of 2) is usually to improve the close packing property by adjusting the particle size of the oxidizing agent to be used and the particle size distribution after mixing in order to increase the content of the oxidizing agent in the propellant. Although carried out, ammonium nitrate, in addition to being difficult to pulverize to a predetermined particle size, has hygroscopicity and easily solidifies, it is difficult to mix and the filling property in the propellant cannot be increased, It was very problematic when it was put to practical use.

[0006]

Means for Solving the Problems As a result of earnest research in consideration of the above-mentioned problems, the present inventor has carried out propulsion by mixing powdered pulverized ammonium nitrate into a predetermined shape and then mixing it with a fuel component. The inventors have found a method for improving the miscibility of ammonium nitrate in the drug and completed the present invention. That is, according to the present invention, the oxidizer in the solid propellant is formed into a predetermined shape by powder molding, and the solid propellant and the crushed oxidizer are powder-formed into a predetermined shape, The present invention proposes and solves a method for producing a solid propellant, which is characterized in that the solid propellant is formed by mixing with the fuel component of 1.

According to the present invention, the surface area per unit weight is minimized by molding the oxidizer powder before mixing it with the propellant, and the mixing property at the time of production is improved. It is possible to improve the filling property of the oxidizer in the propellant and also to improve the specific thrust. As the oxidizer used in the present invention, ammonium nitrate is particularly effective for the above-mentioned reasons, but any powder-formable oxidizer can be used because the filling property is improved.

The shape is preferably spherical in view of the mixing property and the filling property, but the design of the shape may be changed according to the purpose and is not limited to a columnar shape or a prismatic shape. Regarding the size, when considering the practical use as a propellant, the maximum length is 10 m.
About m, the lower limit is preferably about 1 mm from the viewpoint of powder molding efficiency. It is preferable to combine those having different sizes because the filling rate can be improved.

As the powder molding method, compression, wet granulation and the like are possible, and the specific gravity of the obtained molded body is 95 which is the true specific gravity.
% Or more is preferable. The target solid propellant is particularly effective as a composite solid propellant containing an oxidizer as a main component, mixing the oxidizer with another fuel component, and molding the mixture. To form a solid propellant, the molded oxidizer may be replaced with a conventional powdered oxidizer in the general method for producing a solid propellant, and the mixing ratio, production conditions, mixing method, etc. are conventionally used. It is all right. Further, as the other components, fuel components such as binders and additives such as combustion modifiers which are usually used in solid propellants are used.

[0010]

EXAMPLES The present invention will be specifically described below with reference to examples.

[0011]

Example 1 Powdered ammonium nitrate having a particle size of about 117 microns was compressed with a compression force of 100 kg / cm ² for 3 m using a tableting machine.
Using a binder mainly composed of a polybutadiene polymer, one having a diameter of 3 mm and a column having a length of 3 mm and having a measured specific gravity of 96% with respect to the true specific gravity and one in a powder state were used.
It was mixed and molded into a composite solid propellant.

65 wt% oxidizer, 35 wt% binder
However, compared with the powdered one, the load current of the kneader used for mixing was lower, the mixing property was better, and the packing density was higher. did it. At the same time, the specific thrust can be improved.

[0013]

As described above, according to the present invention, the manufacturing problem is solved, and it becomes possible to enhance the filling property of the oxidizer in the solid propellant, thereby improving the total thrust of the solid propellant, The range of application of ammonium nitrate to solid propellants can be expanded.

Claims (5)

[Claims] 1. A solid propellant characterized in that the oxidizer in the solid propellant is formed into a predetermined shape by powder molding. 2. The solid propellant according to claim 1, wherein the solid propellant is a composite solid propellant. 3. The solid propellant according to claim 1, wherein the oxidizing agent is ammonium nitrate. 4. The oxidizing agent having a predetermined shape is a combination of two or more kinds of sizes.
To the solid propellant according to claim 3. 5. The solid propellant according to claim 1, wherein the crushed oxidizer is powder-molded into a predetermined shape and then mixed with another fuel component and molded. Manufacturing method.