JPH05124886A - Ammonium perchlorate composite propellant - Google Patents

Abstract

PURPOSE:To obtain the above propellant which is low in pressure index by specifying the weight average grain sizes of ammonium perchlorate to a prescribed range and using polyether having an azide methyl group as the essential component of a binder. CONSTITUTION:The ammonium perchlorate of an oxidizing agent is used at 70 to 86wt.% of the solid propellant and the weight average grain sizes thereof are specified to 100 to 250mum. The grain sizes are adjusted by mixing particles having 400mum, 200mum, 35mum, 10mum, and 5mum grain sizes at prescribed ratios. The binder is prepd. by adding and mixing a plasticizer (e.g. isodecyl pelargonate), a hardener (e.g. isophorone diisocyanate), a crosslinking agent (e.g. trimethylol propane and a hardening catalyst (e.g. dibutyltin dilaurate) to and with azide methyl methyoxysetane which is an essential component. The oxidizing agent and the binder are then charged at about 80:20 ratio by weight and are intimately mixed in a vacuum at about 60 deg.C; thereafter, the mixture is cast into a prescribed container under vacuum deforming. The molding is cured at about 60 deg.C, by which the above propellant having <=0.2 pressure index is obtd.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to ammonium perchlorate composite propellants having a low pressure index.

[0002]

2. Description of the Related Art In a composite propellant containing ammonium perchlorate (hereinafter referred to as AP) as a main component of a solid propellant, AP is used as an oxidant and a polymer is used as a reducing agent (fuel) and a binder. .. Polyurethane, polybutadiene and the like are used as the polymer, but at present, terminal hydroxypolybutadiene (hereinafter referred to as HTPB) having OH groups at both ends is predominant. The combustion reaction is caused by the redox reaction of these oxidizer and binder, and the reaction temperature thereof reaches 3000K.

The burning rate of the solid propellant is determined by the balance between the heat generated by the reaction in the vicinity of the combustion reaction surface and the reaction in the gas phase and the amount of heat returned to the solid surface. In the case of an AP composite propellant, the combustion rate is also determined by the heat balance, but the combustion reaction has a rate-determining step of the AP diffusion rate rather than the AP binder reaction rate on the combustion surface. Is strongly dependent on the concentration of AP contained in the propellant and the weight average particle size. Generally burning rate is AP
It increases as the concentration increases and as the weight average particle size decreases. Further, as a method for controlling the burning rate, there is a method using a catalyst, and in this case, it depends on the catalyst concentration and type. Iron oxide (Fe ₂ O ₃ ) is generally used as a catalyst.
Etc. are used.

The combustion rate also depends on the pressure around the propellant because the gas phase reaction is involved as described above. The dependence of the burning rate on the pressure is represented by a pressure index, for example, A
In the case of P / HTPB propellant, it shows a pressure index of 0.3-0.5. The propellant pressure index has an important meaning in the design of propellant. In other words, when propellant having a high pressure index is burned, when a slight pressure fluctuation occurs in the combustion chamber, the combustion speed fluctuates greatly, resulting in unstable combustion, and stable combustion performance cannot be obtained. Further, in some cases, the combustion of the propellant may be interrupted or the motor case may be destroyed. Therefore, it is preferable that the pressure index of the propellant is as small as possible, and the propellant having a pressure index of 0 is most preferable. When the pressure index is 0, the combustion speed does not change even if the pressure fluctuates, and stable combustion performance can be obtained. Therefore, it is considered to make the pressure index of the AP composite propellant close to zero.

[0005]

In recent years, in order to increase the energy of AP composite propellants, it has been considered to use a high energy polymer as the main component of the binder. Although many studies have been carried out as a binder with high energy, for example, the polyether having an azidomethyl group disclosed in US Pat. No. 4,268,450 is
Research as a high energy binder has been actively conducted.

When this polyether having an azidomethyl group is used as a binder for AP composite propellant, the energy of the propellant is higher than that of AP / HTPB propellant. As a result of recent research, it has been found that the pressure index of the polyether having the AP / azidomethyl group shows a value of 0.3 to 0.5. A pressure index of 0.3 to 0.5 is a value that can be sufficiently practically used, but as described above, the closer the pressure index is to 0, the more stable combustion characteristics can be obtained, which is very important in designing a propellant. Will be advantageous. Therefore, the inventors of the present invention have made earnest studies as to whether or not the pressure index can be further lowered, and succeeded in obtaining a propellant having a low pressure index by controlling the weight average particle diameter of AP.

[0007]

The present invention relates to a composite propellant containing ammonium perchlorate as a main component, wherein the weight average particle diameter of the ammonium perchlorate is 100.
It is ~ 250 μm, and the main component of the binder is a polyether having an azidomethyl group, which is an ammonium perchlorate composite propellant.

The present invention will be described below. In the present invention, AP is preferably in the range of 70 to 86% by weight of the solid propellant. When AP is less than 70% by weight, the burning rate becomes low, which is not preferable in operation. When AP exceeds 86% by weight, the propellant has a lower propellant power than the AP / HTPB propellant, and thus the effect of using a polyether having an azidomethyl group is reduced. Furthermore, the weight average particle diameter of AP is required to be 100 to 250 μm, which is 400 μm.
It is adjusted by mixing AP having a particle size of m, 200 μm, 35 μm, 10 μm, 5 μm in a predetermined ratio, but the weight average particle size of AP does not depend on the individual particle size of the mixed AP. is important. The adjustment of the weight average particle diameter is performed by specifically adjusting the A of 400 μm and 200 μm.
P is adjusted using a sieve and is 35μm, 10μm, 5μ
m is measured and adjusted by a subsieve sizer particle size distribution measuring device. For example, A passing through a 400 μm sieve
When 33 parts by weight of P, 34 parts by weight of AP passing through a 200 μm sieve, and 33 parts by weight of AP having an average particle size of 10 μm measured by a subsieve sizer particle size analyzer are mixed, the weight average particle size of AP is , 400 × 33 + 200 × 34 + 10 × 33 ──────────────────── = 203.3 μm 100.

The weight average particle diameter of AP in the propellant is 100 μ
When it is smaller than m, the pressure index becomes almost the same as that of the AP / HTPB propellant, and the effect is reduced. Further, when the weight average particle diameter of AP is larger than 250 μm, the burning rate becomes low, which is not preferable in operation. A more preferable weight average particle diameter of AP is in the range of 200 to 250 μm. Azidomethylmethyl oxetane (AMMO) is one of the polyethers having an azidomethyl group as the main component of the binder.

The polyether having an azidomethyl group is a glycidyl azide polymer (GAP) which is a terminal hydroxyl group polyether having a methyl azido group in the side chain disclosed in US Pat. No. 4,268,450 in addition to AMMO.
And bisazidomethyl oxetane (BAMO), but any one having an azido group in the side chain may be used.

The combustion speed of the propellant of the present composition is such that the gas is sent from a gas cylinder having a predetermined pressure into a pressure vessel of a constant volume to maintain a constant pressure while the gas is flowing, and the combustion distance of the propellant and its distance are burned. It is measured by a chimney-type strand tester which measures the burning rate from the burning time required for That is, the burning rate is such that the outer peripheral surface of a cylindrical propellant having a diameter of 7 mm and a length of 70 mm is coated with an epoxy resin, holes are formed in the side surface of the propellant at regular intervals, and the fuse is inserted in the hole. Pass the line. This test piece is 2
After adjusting the temperature at 5 ° C for 2 hours or more, the pressure was adjusted within the range of 0.5 to 30 MPa by the chimney-type strand tester, and the burning speed at each pressure was adjusted to the distance between the fuse wires and the fire ignited on one of the fuse wires. And the time until the other fuse wire is blown. Specifically, it is calculated by the following formula The burning rate (r) has the following relationship with the burning pressure (p).

R = ap ⁿ where a is a constant and n is a pressure index. By the above method, the ammonium perchlorate composite propellant of the present invention can be obtained.

[0013]

The present invention will be described in detail below with reference to examples. AP which is the main component of propellant is 400μm, 200μ
having passed through a m sieve and having a size of 10 μm measured by a subsieve sizer particle size distribution measuring device, and 20
What passed through a 0 μm sieve and those of 35 μm and 5 μm measured by a subsieve sizer particle size distribution measuring device were mixed at a predetermined ratio to prepare a target weight average particle diameter. The compounding ratio of AP is shown in Table 1.

The binder is the main component AMMO100.
20 parts by weight of isodecyl pelargonate (IDP), which is a plasticizer, 1.0 equivalent of isophorone diisocyanate (IPDI), which is a curing agent, and trimethylolpropane (TMP), which is a bridging agent, per part by weight. 5.0 parts by weight,
Curing catalyst dibutyltin dilaurate (DBTD
Add 0.1 parts by weight of L) and mix.

Thereafter, the AP and the binder are mixed in a weight ratio of 8
The mixture was charged at a ratio of 0:20, vacuum mixed at 60 ° C. for 30 minutes, and then cast in a predetermined container while performing vacuum degassing. The cast compound was cured at 60 ° C for 7 days to obtain the propellant of the present invention. This propellant was processed into a cylindrical shape with a diameter of 7 mm and a length of 70 mm according to the above-mentioned measuring method of burning rate, and its outer peripheral surface was coated with epoxy resin. Fuse wires were passed through the side surface of the propellant at regular intervals. A test piece was prepared.
After adjusting the temperature of this test piece at 25 ° C. for 2 hours or more, the pressure was adjusted in the range of 0.5 to 30 MPa by a chimney type strand tester, and the burning rate at each pressure was measured for the distance between the fuse wires and one of the fuse wires. It was determined by measuring the time until the ignited flame progressed and the other fuse wire was blown. Obtained burning velocity (m / s) and pressure (MPa)
The relationship is shown in FIG. In addition, the weight average particle diameter of AP (μ
The relationship between m) and the pressure index is shown in FIG.

[0016]

[Table 1]

[0017]

Comparative Example 1 AP weight average particle diameter is 100 to 250 μm.
Of which AP passed through a sieve of 400 μm and 200 μm so as to fall within the range of 10 μm measured by a subsieve sizer viscosity distribution measuring device, and 200 μm
The mixture that passed through the m sieve and the one having a size of 35 μm and 5 μm measured by a subsieve sizer viscosity distribution measuring device were used and mixed at a predetermined ratio. Table 2 shows the blending ratio of AP. The binder is 20 parts by weight of IDP and 1.0 equivalent of IPDI with respect to 100 parts by weight of HTPB which is the main component.
TMP (5.0 parts by weight) and DBTDL (0.1 parts by weight) were added, and the mixture was prepared by the method according to the example, and the burning rate was measured by the same method. Obtained burning velocity (m / s) and pressure (M
The pressure index is obtained from the relationship of (Pa), and the relationship between the obtained pressure index and the particle size (μm) is shown in FIG.

In FIG. 2 showing the relationship between the pressure index of the AP / HTPB propellant and the weight average particle diameter of AP, the pressure index tends to decrease as the weight average particle diameter increases. The pressure index is larger than that of AMMO composite propellant, and the pressure index is 0.3 to 0.5.
Indicates the value of.

[0019]

[Table 2]

[0020]

Comparative Example 2 AP passed through a 200 μm sieve so that the weight average particle diameter of the AP was 100 μm or less,
A propellant was prepared by a method according to the example, which was mixed with a binder having the same composition as that of the example in the same manner by using the ones having a size of 35 μm and 5 μm measured with a subsieve sizer Then, the burning rate was measured by the same method. The compounding ratio of AP is shown in Table 3. Also,
The pressure index is obtained from the obtained relationship between the burning rate (m / s) and the pressure (MPa), and the relationship between the obtained pressure index and the particle size (μm) is shown in FIG.

In FIG. 2 showing the relationship between the pressure index of the AP / AMMO propellant and the weight average particle size of AP, when the weight average particle size of AP is 100 μm or less, the pressure index is AP.
/ HTPB propellant equivalent, showing a value of about 0.5.

[0022]

[Table 3]

[0023]

INDUSTRIAL APPLICABILITY The AP / AMMO composite propellant of the present invention can easily adjust the pressure index without using a catalyst or the like, and lowers the pressure index to about one-third that of the AP / HTPB composite propellant. This is extremely effective in designing a rocket motor having stable combustion performance in a wide pressure range.

[Brief description of drawings]

FIG. 1 is a burning rate characteristic diagram of an AP / AMMO composite propellant of the present invention.

FIG. 2 is a diagram showing the relationship between the pressure index of the AP / AMMO composite propellant and the pressure index of the AP / HTPB composite propellant of the present invention and the average particle size of AP.

Claims (2)

[Claims] 1. A composite propellant containing ammonium perchlorate as a main component, wherein the weight average particle diameter of said ammonium perchlorate is 100 to 250 μm, and the main component of the binder is a polyether having an azidomethyl group. Ammonium perchlorate composite propellant characterized by: 2. The weight average particle size of ammonium perchlorate is 200 to 250 μm, and the polyether having an azidomethyl group in the main component of the binder is azidomethylmethyloxetane. Ammonium perchlorate composite propellant.