JPH03202664A - Insulator for rocket propellant powder - Google Patents

Abstract

PURPOSE:To have sanitary improvement with suppression of burnout and elimination of use of asbestos by forming an insulator, which is interposed between a rocket propellant powder and the inner wall of a motor case, from rubber, heat absorptive metal oxides, aramid fiber, etc., having respective specified shares in the proportion by weight. CONSTITUTION:Between the inner wall of a rocket motor case and a rocket propellant powder, insulator consisting of rubber compound is interposed in order for flame not to touch the case inner wall and in order to acquire a specific combustion promotion curve. The insulator shall contain as major constituents 100 parts by weight rubber, 50-150 parts by weight heat absorptive metal oxide, and 20-70 parts by weight aramid fiber or polybenz-imidasol fiber. Thereby rubber and fiber are tied firmly to suppress carbonization, exfoliation, and burnout of the insulator when the rocket propulsive powder is combusting and to eliminate use of asbestos, etc., as in conventional arrangement, and thereby the working environment is maintained sanitized.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to an insulator for rocket propellants which has little burnout during propellant combustion and is hygienic during processing.

<Prior Art> In general, a rocket motor case has a space between the rocket propellant and the inner wall of the motor case in order to prevent the flame from directly hitting the inner wall of the motor case and to obtain a predetermined combustion propulsion curve. An insulator made of a rubber compound is interposed between the two.

Insulators are required to have excellent combustion suppressing power and heat resistance, high chemical resistance, high aging resistance, good storage stability, and high heat insulation properties.

Conventionally, insulators for rocket propellants have been made in an attempt to satisfy the above-mentioned properties, for example by adding endothermic metal oxides such as basic magnesium carbonate, aluminum hydroxide, magnesium hydroxide, kaolin clay, or asbestos powder to natural rubber or bottom rubber. Compounds containing heat-resistant materials such as, for example, are widely used.

<Problems to be Solved by the Invention> Ashest is mixed in the rubber compound to prevent the rubber matrix from scattering in high-temperature, high-velocity combustion gas, that is, to reduce burnout, but it is not sufficiently effective. Moreover, since the ashest used is in powder form, it must be weighed and kneaded.

It is easily dispersed during processing processes such as rolling, and if inhaled for a long time, it can cause pneumoconiosis and lung cancer. Therefore, it is necessary to install a local exhaust system in the workplace, use a dust mask and a hose mask, and make sure that the work environment and facilities are There were drawbacks such as increased costs and difficulty in work.

It is an object of the present invention to simultaneously solve the two problems that such conventional rocket propellant insulators had.

Means for Solving the Problems> In order to solve the above problems, the present invention uses 100 parts by weight of rubber, 50 to 150 parts by weight of an endothermic metal oxide, and 20 to 70 parts by weight of aramid fiber or polybenzimidazole fiber. This product provides an insulator for rocket propellants, which is the main component. Rubber is natural rubber.

Base rubber etc. are used as appropriate, but ethylene, propylene,
A terpolymer of dienes (hereinafter referred to as "rEPDM") is most often used in view of weather resistance, chemical resistance, high filling property, etc. Endothermic metal oxides undergo an endothermic reaction at high temperatures, and the decomposed gas is smokeless and harmless. Basic magnesium carbonate, which can be mixed into rubber in large quantities and does not generate gas that reacts with propellants, is 50 to 150. Parts by weight are used. The aramid fiber used is polyparaphenylene terephthalamide, such as Kevlar (registered trademark) manufactured by DuPont.
As the polybenzimidazole, PBI (registered trademark) manufactured by Celaniz, Inc., USA, etc. are used.

<Function> The aramid fibers and polybenzimidazole used in the present invention have extremely good affinity with the rubber matrix,
Therefore, the rubber and fibers are strongly bonded, and when the insulator is carbonized by the high-temperature gas generated during the combustion of rocket propellant, the progress of carbonization is slowed down, and peeling is also less likely to occur, resulting in less burnout.

Also, since it does not use asbestos, which is said to cause pneumoconiosis and lung cancer if inhaled in airborne dust for a long period of time, it is hygienic and does not require any special equipment or equipment.

<Example> EPDM 100 parts by weight sulfur 2
〃 Zinc white 5 〃 Stearic acid 1 Vulcanization accelerator 5 // Titanium oxide 20 `` Basic magnesium carbonate 100 〃 *Mixed accelerator consisting of thiuram type, dithiocarbamate type, and thiazole type.

The above-mentioned recipe table is called a rubber compounding list. Various types of fibers as described below were blended with 100 parts by weight of EPDM in this rubber compounded hese, and the physical properties of the vulcanized product were measured.

Number 1. 2. 3,4. 5,6,7,8.9 carbonized fiber 42" polybenzimidazole fiber -42" phenolic fiber --372 Aku JJ /L, fiber ---35" aramid fiber
------2042"70 ashest fiber ------
-----100" tensile strength (kgf/CTA) 85
50 65 85 95 85120110 70 Elongation (%) 600 20060010060020
0150 80350 Hardness (JIS-A) 70
80 70 85 60 80 85 90 80*
: The capacity ratios for E P DMloo are all 29.

Insulator holder (nozzle hole outer diameter 27.4 mm, same inner diameter 19-2ut + inlet hole outer diameter 61.4 m, same inner diameter 53.21 m, length 80.On
) to a thickness of 4.0 fl by press vulcanization.

Combustion gas generated by the propellant in this insulator holder (temperature 3.457°, ejected gas velocity 1.08
4m/sec, gas average molecular weight 28.0, gas density 7°9
0 Xl0-'g/cj, gas constant pressure specific heat 0.806 C
al/g'K) is introduced from the inflow hole and passed through, and the velocity of the combustion gas as seen from the nozzle side is Matsuha〇, 1.0.05.0
．． 02 position (7.9mm from the nozzle end, 21
．． The burn thickness (m/sec) was measured at a distance of 9 fl, 49.0 m away.

m 12345678 Matsuha O110, 40, 250, 40, 40, 40, 3
70,240,20〃0.05 0.40.19 0.
4 0.4 0.4 0.21 0.170.20〃0
．． 02 0.240.19 0.21 0.21 0,
34 0.1B 0.160.190.35 0.25 0.19 20 to 70 parts of aramid fiber to 100 parts by weight of EPDM
It can be seen that the burnout was smaller in the case of adding 42 parts by weight of polyhenzimidazur fiber.

Here, only the case in which 42 parts by weight of the latter was added was shown as an example, but the results obtained when adding 20 to 70 parts by weight were exactly the same as the former. Both are 70% per 100 parts by weight of EPDM.
When added in excess of parts by weight, kneading properties and rolling properties were poor, resulting in poor practicality.

In addition, in this example, NO, 2, No, 6 to N0.8
In this case, local exhaust ventilation, dust masks, hose masks, etc. were not used.

<Effects> By carrying out the above invention, burnout of insulators for rocket propellants is reduced, a predetermined combustion propulsion curve is obtained, and aramid fibers and polyhenrygodazole fibers that are not likely to cause pneumoconiosis or lung cancer can be used. Because it is used, local exhaust equipment is not required, and the cost is lower.
Furthermore, there is no need to wear a dust mask or hose mask, making work easier.

Claims (1)

[Claims] 100 parts by weight of rubber, 50 to 150 parts by weight of endothermic metal oxide, 20 parts by weight of aramid fiber or polybenzimidazole fiber
An insulator for rocket propellants containing ~70 parts by weight as a main component.