JPH06128069A - Flame-retarded nitrocellulose-based smokeless powder - Google Patents

Abstract

PURPOSE:To obtain the subject smokeless powder excellent in forging resistance by substituting inert ester group for the nitrate ester group in the nitrocellulose molecule in a nitrocellulose-based smokeless powder. CONSTITUTION:Part of the nitrate group in nitrocellulose as binder component is substituted, at a substitution degree of 2.0-0.5, by inert ester group such as acetyl group, butyl group or other ester group of inorganic acid except other long chain carboxylic acids and nitric acid, and the resulting modified nitrocellulose is incorporated with 10-90wt.% of a mixed esterified cellulose 0.5-2.0 in nitration degree and the rest of a plasticizer such as nitroglycerin, a stabilizer such as ethyl centralit and an oxidizing agent such as ammonium perchlorate, and the resultant mixture is cast in a specified vessel, heated and gelled, thus affording the objective smokeless powder excellent in forging resistance without impairing ignitability and combustibility.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a propellant and propellant composition, and more particularly to a propellant and propellant obtained by converting conventional nitrocellulose into flame retardant nitrocellulose and imparting LOVA (anti-tank) property. The present invention relates to a flame-retardant nitrocellulose-based smokeless explosive powder.

[0002]

2. Description of the Related Art Conventionally, propellants and smokeless propellants have a nitrification degree of 2.67 to 2.81 (nitrogen content:
Nitrocellulose having good flammability (12.60 to 13.25%) is used in a proportion of 20 to 90% by weight.
In recent years, there has been an increasing demand for propellants and propellants that have anti-resistance properties against accidents such as accidents and shots during battle without impairing flammability. Conventional propellants and propellants using nitrocellulose as a binder It has become clear that the sensitivity to heat and shock is high and these requirements cannot be satisfied.

There have been extensive studies to replace nitrocellulose with other esterified celluloses.
Acetyl cellulose, ethyl cellulose, and acetyl butyl cellulose were tried, but even if they were able to impart anti-tank properties, they were inferior in ignitability and flammability and could not be put into practical use. To improve these, a method of mixing nitrocellulose was taken. .

However, with physical mixing, poor heat resistance and poor impact resistance of nitrocellulose appeared separately, and satisfactory results could not be obtained. Further, when nitramine was used as the oxidant, the pressure index of the burning rate was 0.7 or less for practical use, but it showed a high value close to 1.0.

Therefore, there has been a demand for the development of a smokeless explosive which has good mechanical properties based on the structure of cellulose and has anti-tank properties without impairing ignitability and combustibility.

[0006]

DISCLOSURE OF THE INVENTION As a result of intensive studies to solve these problems, the present inventor has found that instead of physically mixing a component having heat resistance with nitrocellulose, The present invention has been accomplished by finding that nitrocellulose can be made flame-retardant by substituting the nitrate ester group with an inactive ester group.

[0007]

The present invention is based on the general formula of repeating units of esterified cellulose. (In the formula, x + y + z is 3, and 0.5 ≦ x ≦ 2.5, 0
≦ y ≦ 0.5, 2.5 ≦ z ≦ 0.5) in which a part of the nitrate (ONO ₂ ) group of nitrocellulose is substituted with an inert ester group such as acetyl group. Esterified cellulose is used as a binder, and the amount of the binder is 10 to 90% by weight of the total composition, which is a smokeless explosive, wherein the inert ester group has a butyl group or a longer group than acetyl group. One or more selected from the group consisting of carboxylic acid of chain and ester group of inorganic acid other than nitric acid, and the degree of substitution is 2.0 to 0.5
And a smokeless explosive having at least one flame-retardant nitrocellulose having a nitrification degree of 0.5 to 2.0 as a binder component.

The flame-retarded nitrocellulose used in the present invention is, for example, acetylated nitrocellulose, by a conventional method, for example, by reacting nitrocellulose having a nitrification degree of 2.5 or more with acetic anhydride in benzene. can get. In this case, the degree of acetylation can be adjusted by the addition amount of sulfuric acid as a catalyst. The acetylated nitrocellulose used in the present invention has an acetylation degree of 2.0 to 0.5.
And the nitrification degree must be 0.5 to 2.0.
When the degree of acetylation is 0.5 or less, improvement in heat resistance and impact resistance cannot be achieved. If the degree of acetylation is 2.0 or more, good ignitability and flammability cannot be obtained.

When the nitrification degree is 0.5 or less, good ignitability and combustibility cannot be obtained, and when the nitrification degree is 2.0 or more,
Heat resistance and impact resistance cannot be obtained.

The degree of acetylation and the degree of nitrification herein are measured by any of the following methods.

[0011] (1) infrared spectroscopy sample was dissolved in acetone or ethyl acetate take infrared absorption spectrum, the degree of acetylation 1750 cm ^-1, nitrification degree of the hydroxyl groups of the methylene peak and 3330cm ^-1 of 2950 cm ^-1 It is determined from the intensity ratio of peaks by a calibration curve.

(2) Elemental analysis method A fixed amount of a sample is burned to analyze the% concentration of carbon, hydrogen, and nitrogen, and the concentration of oxygen is subtracted from 100%. From this result, the degree of acetylation and the degree of nitrification are calculated.

The flame-retardant nitrocellulose smokeless explosive of the present invention contains an oxidizing agent, a plasticizer, and a stabilizer. The object of the present invention is not achieved only by the flame-retarded nitrocellulose, and the object is achieved by coexistence of the flame-retarded nitrocellulose and these components.

As the oxidizing agent used in the present invention, ammonium perchlorate (AP), cyclotrimethylene trinitramine (RDX), cyclotetramethylene tetranitramine (HMX), nitroguanidine (NGu), dinitrotoluene ( Examples thereof include inorganic oxidizers such as DNT) and organic oxidizers, or a mixture of two or more kinds.

The plasticizer used in the present invention includes nitroglycerin (NG), trimethylolethane trinitrate (TMETN), triethylene glycol dinitrate (TEGDN), diethylene glycol dinitrate (DEGN) as an energy plasticizer. Or a mixture of two or more thereof. Examples of the inert plasticizer include diethyl phthalate (DEP), dibutyl phthalate (DBP), triacetin (TA), acetyltriethyl citrate (ATEC), and the like, or a mixture of two or more thereof. The plasticizer used in the present invention may be a mixture of one or both of an energy plasticizer and an inert plasticizer.

The stabilizers used in the present invention are ethyl centrallite (ECL), diphenylamine (DPA),
2-Nitrodiphenylamine (2-NDPA) and resorcin (RSC) may be used alone or as a mixture of two or more kinds.

The smokeless explosive for flame-retardant nitrocellulose propellant of the present invention is produced by a conventional method, for example, as follows.

That is, a flame retardant nitrocellulose represented by the above general formula which is a binder component is mixed with a plasticizer and a stabilizer or further an oxidizing agent with a solvent, and this mixture is drawn through a predetermined die and after cutting, cut. Obtained by air drying.

The flame-retardant nitrocellulose-based propellant-free smokeless explosive of the present invention is produced by a conventional method, for example, as follows.

That is, the flame-retardant nitrocellulose represented by the above general formula, which is the binder component, and a plasticizer and a stabilizer or an oxidizer are added and vacuum mixed, and the mixture is cast into a predetermined container and heated for a predetermined time. It is obtained by warming and gelling.

[0021]

EXAMPLES The present invention will be described in detail below with reference to examples. Example 1 Nitrocellulose (nitrogen content = 12.6%) was dissolved in acetic anhydride, heated to 40 ° C., benzene was added and stirred to completely dissolve nitrocellulose. After that, sulfuric acid as a catalyst was added to start the reaction, these mixtures were taken out at an appropriate time and cooled with ice, and ethanol was added to precipitate acetylated cellulose. This was suction filtered, washed well with warm water to neutralize the remaining acid, further washed and vacuum dried at 60 ° C. to obtain acetylated cellulose.
The degree of acetylation can be adjusted by changing the amount of catalyst and the reaction time.

FIG. 1 shows the decomposition calorific values of nitrocellulose as a starting material and acetylated nitrocellulose having an acetylation degree of 0.6, 1.5 and 2.0, which were obtained by a differential scanning calorimeter (DSC). Show. The decomposition calorific value decreases linearly as the degree of acetylation increases, and the degree of acetylation is almost 2.5.
It is estimated that the calorific value becomes zero.

The differential scanning calorimeter (D) was used to determine the thermal decomposition characteristics and ignition characteristics of nitrocellulose as a starting material and acetylated nitrocellulose having an acetylation degree of 2.0 by changing the heating rate.
The result obtained by (SC) is shown in FIG. Nitrocellulose transitioned from pyrolysis to ignition at a heating rate of 10 ° C / min or more, whereas acetylated nitrocellulose produced 60 ° C / min.
It does not ignite even above the above, and the thermal decomposition peak temperature is about 10 ° C.
Increased by -20 ° C. Thus, the effectiveness of the present invention for improving the heat resistance and flame retardancy by introducing an inert group into the molecule of nitrocellulose was confirmed.

Example 2 Nitrocellulose as a starting material and the degree of acetylation were 0.
Propellants having 6, 1.5 and 2.0 acetylated nitrocellulose as a binder were prepared with the compositions shown in Table 1.

[Table 1]

Using the obtained propellant, a drop sensitivity test and a closed bomb combustion test were conducted by the following methods.

(Falling Sensitivity Test) The three types of propellant and Comparative Example 1 were tested for outer diameter 3.5 mm, inner hole diameter 0.3 mm, and length 6.
One grain of 0 mm 7-hole tubular shape at -30 ° C, 20
Adjust the temperature to ℃, 50 ℃, drop a 5kg drop from various heights with a drop sensitivity tester, judge whether it is explosive / non-explosive, and find the drop height of 1/6 explosion point, JIS standard It was expressed as a grade.

(Closed Bomb Combustion Test) In a closed pressure vessel having a volume of 200 ml, 50 g of the three propellants and Comparative Example 1 were conditioned at -30 ° C, 20 ° C and 50 ° C and ignited with black powder. Then, the burning rate, the pressure index of the burning rate, and the temperature sensitivity were determined.

The results of the drop sensitivity test are shown in FIG. Each of the propellants has a sensitivity of grade 5 or higher at all temperatures, and especially at a low temperature of -30 ° C, all of the propellants are 6 or less.
The sensitivity was low. It has been clarified that a low-sensitivity propellant of Grade 5 or higher has no reaction in a shooting sensitivity test, and it is presumed that all three types of propellant have anti-fungal properties against shooting. Comparative Example 1 is a typical propellant which is widely used at present, but it is well known that the sensitivity increases as the temperature decreases. That is, the conventional propellant has high sensitivity in a low temperature region, and the gun may explode due to abnormal combustion at the time of firing, but the propellant can also be expected to have an effect of preventing this.

The results of the temperature sensitivity measurement of the pressure index obtained by the closed bomb combustion test are shown in FIG. All three types of propellants have low temperature sensitivity of pressure index as in the comparative example,
The pressure index was also 0.7 or less, which is practically preferable. Conventional propellants containing nitramine have a high pressure index of about 1.0, but it has been shown that the pressure index can be reduced to the same level as conventional propellants by using flame-retardant nitrocellulose as a binder. .

[0030]

EFFECTS OF THE INVENTION The flame-retardant nitrocellulose smokeless explosive of the present invention contains, as a binder, a flame-retardant nitrocellulose obtained by substituting a part of the nitrate ester group of nitrocellulose with an inactive ester group. It has heat resistance and impact resistance, and has good ignitability and combustion characteristics. Further, it is an extremely useful invention because it has the advantage that it can be handled by changing the degree of substitution of the inert ester and the degree of nitrification according to the required degree of heat resistance and impact resistance.

[Brief description of drawings]

FIG. 1 is a graph showing a measurement example of the degree of acetylation and the decomposition calorific value of the flame-retardant nitrocellulose of the present invention.

FIG. 2 is a graph showing ignition characteristics of nitrocellulose and flame-retardant nitrocellulose of the present invention.

FIG. 3 is a graph showing the measurement results of the drop sensitivities of the propellants of Examples 1 to 3 and the conventional propellant of Comparative Example 1 at −30 ° C., 20 ° C. and 50 ° C.

FIG. 4 is −30 ° C., 20 ° C., 50 of Example 1 and Comparative Example 1.
It is a graph which shows the pressure index of the burning rate in ° C.

Claims (2)

[Claims] 1. A mixed esterified cellulose obtained by substituting a part of the nitrate ester group of nitrocellulose with an inactive ester group as a binder, and the amount of the binder is 10 to 90% by weight of the whole composition. Flame-retardant nitrocellulose smokeless gunpowder for propellants and propellants. 2. The inert ester group is one or more selected from the group consisting of an acetyl group, a butyl group or other long-chain carboxylic acid and an ester group of an inorganic acid other than nitric acid, and the degree of substitution thereof is The flame-retardant nitro for propellants and propellants according to claim 1, which is at least one kind of flame-retardant nitrocellulose having a nitrification degree of 2.0 to 0.5 and a nitrification degree of 0.5 to 2.0. Cellulosic smokeless powder.