KR20110128736A - Thermosetting solid propellant composition comprising tertiary amine, and method for controling cure rate of the composition - Google Patents

Abstract

PURPOSE: A thermosetting solid propellant composition containing tertiary amine and a method for controlling the hardening rate of the composition are provided to increase a time for maintaining the flowage of a propellant by controlling the viscosity increasing rate of the propellant composition. CONSTITUTION: A thermosetting solid propellant composition is based on nitrate-ester-polyether and includes bismuth subsalicylate as a combustion characteristic modifier. The propellant composition further includes tertiary amine. The content of the tertiary amine is 0.005-0.1 weight% based on the total weight of the entire propellant composition. The tertiary amine is selected from a group including 1,4-diazabicyclo[2.2.2]octane, 1,5- diazabicyclo[4.3.0]non-5-ene, and 1,8- diazabicyclo[5.4.0]undec-7-ene.

Description

Thermosetting solid propellant composition comprising a tertiary amine and a method of controlling the curing rate of the composition {THERMOSETTING SOLID PROPELLANT COMPOSITION COMPRISING TERTIARY AMINE, AND METHOD FOR CONTROLING CURE RATE OF THE COMPOSITION}

The present invention relates to thermosetting solid propellant compositions comprising tertiary amines and to methods of controlling the cure rate of such compositions.

Minimum smoke propellants of the nitrate ester polyether (NEPE) family are nitramine-based oxidants, such as 1,3,5-trinitroperhydro-1,3,5-triazine. (1,3,5-trinitroperhydro-1,3,5-triazine, RDX), 1,3,5,7-tetranitro-1,3,5,7-tetrazocan (1,3,5,7 -tetranitro-1,3,5,7-tetrazocane (HMX) or 2,4,6,8,10,13-hexanitro-2,4,6,8,10,12-hexaazaisobutytan ( 2,4,6,8,10,12-hexanitro- 2,4,6,8,10,12-hexaazaisowurtzitane (HNIW), etc., so the rate of change in combustion rate for pressure changes [pressure exponent] Is very large, above 0.6. Therefore, ballistic modifiers such as lead compounds or bismuth compounds are used to lower the pressure index. Of these, bismuth compounds, especially bismuth subsalicylate, are environmentally friendly materials, unlike lead compounds, and are also excellent in improving combustion characteristics.

Solid propellants, on the other hand, are generally formed by uniform casting of all raw materials and casting in a constant mold for a period of time (pot life, hereinafter referred to as "port life") that allows the propellant flow to be maintained to the extent that the casting process is possible. Cure for 7 to 10 days in a thermostat of 50 to 60 ℃. By the way, the NEPE-based propellant composed of a polar binder system has a property of dissolving metal ions or acidic substances that affect the curing reaction, so that some bismuth compounds, lead compounds, etc., which are used as combustion characteristics improving agents, are mixed with the propellant. It can be dissolved in the propellant raw materials during the process, which will have a profound effect on the curing reaction. In other words, the dissolved metal ions act as a strong catalyst in the urethane curing reaction, which excessively accelerates the curing reaction of the propellant, thereby rapidly increasing the viscosity of the propellant in which the mixing process is completed, and thus insufficient time for casting the propellant. Done. That is, a problem arises in that the pot life in which the flowability of the propellant is maintained is not properly maintained.

 Therefore, when mixing a combustion property improving agent such as bismuth subsalicylate at 50 ° C., which is a normal process temperature when mixed with a nitrate ester plasticizer and a polar polymer, the propellant composition cures too quickly to rapidly increase the viscosity, This results in shortening pot life.

Since the curing reaction rate is greatly influenced not only by the curing catalyst but also by the temperature, when the curing reaction is accelerated by the curing catalyst component, the mixing and casting process of the propellant is conventionally performed at a normal process temperature of 50 ° C. in order to slow down the curing reaction rate. Attempts have been made to run at temperatures below 15 ° C. For example, in US Pat. No. 6,168,677, the mixing and casting process of the propellant was carried out at a temperature of 15 ° C. or less to reduce the rate of viscosity rise of the propellant and to prolong the pot life. It is not desirable to use a refrigeration apparatus to keep it below, which leads to an increase in manufacturing cost.

The present inventors earnestly studied for the development of the NEPE-based solid propellant composition composition which can be mixed and cast at room temperature without using a separate cooling device, and as a result, NEPE containing bismuth subsalicylate as a combustion improving agent. The present invention has been completed by finding out that additional inclusion of a tertiary amine in the systemic solid propellant composition can increase the time for which the flowability of the propellant is maintained by controlling the rate of viscosity rise of the composition.

Accordingly, it is an object of the present invention to provide a nitrate ester polyether (NEPE) series solid propellant composition further comprising a tertiary amine.

Another object of the present invention is to use a tertiary amine to control the rate of viscosity increase of the nitrate ester polyether (NEPE) based solid propellant compositions to provide a method for increasing the time that the propellant maintains flowability.

Another object of the present invention is to prepare a nitrate ester polyether (NEPE) -based solid propellant composition, characterized in that the mixing and casting process is carried out at room temperature that can be cooled by using ordinary tap water without using a separate cooling device To provide a way.

Still other objects and advantages of the present invention will become apparent from the following detailed description, claims and drawings.

The present invention relates to a nitrate ester polyether (NEPE) -based thermosetting solid propellant composition comprising bismuth subsalicylate as a combustion characteristics improving agent, wherein the NEPE-based solid propellant further comprises a tertiary amine. To provide a composition.

In the nitrate ester polyether-based lead-free propellant, a lead compound or bismuth compound is used as a combustion improving agent. The bismuth compound, particularly bismuth subsalicylate, is an environmentally friendly material unlike the lead compound and improves combustion characteristics. The effect is also excellent.

However, bismuth subsalicylates are known to be strongly catalyzed in urethane curing reactions and to promote urethane curing reactions in acidic conditions. Bismuth subsalicylates, when mixed with nitrate ester plasticizers and polar polymers, acid).

Although the cure rate of the thermosetting solid propellant composition is known to be primarily influenced by temperature and cure catalyst, the present inventors have found that bismuth subsalicylate is suitable for the acid generated in the mixing process in that it promotes urethane cure reactions, especially in acidic conditions. It was conceived that neutralization with a base would allow control of the cure rate of the propellant. Therefore, by properly neutralizing the acid generated in the mixing process of the propellant with the tertiary amine through actual experiments, it is possible to control the curing rate of the propellant, and in this case, the mixing process and the casting process can be performed at a higher temperature than in the prior art. The present invention was completed by confirming the points.

There are many substances that can neutralize acids. However, inorganic bases, or primary or secondary organic amines, cannot be used because they cause a urethane reaction or aging of the propellant. For this reason, in this invention, the tertiary amine which does not cause urethane reaction or aging of a propellant is used as a base for neutralizing the acid produced | generated during the mixing process of a propellant composition.

In a preferred embodiment of the invention, the tertiary amine is characterized in that it is a nonvolatile amine. Since the propellant mixing process is generally carried out in a vacuum, the use of a nonvolatile tertiary amine is preferred because it does not volatilize even in a vacuum.

Examples of the nonvolatile tertiary amine include 1,4-diazabicyclo [2.2.2] octane (hereinafter referred to as “DABCO”) and 1,5-diazabicyclo [4.3.0] non-5- Yen (hereinafter referred to as “DBN”), 1,8-diazabicyclo [5.4.0] undes-7-yen (hereinafter referred to as “DBU”), and the like, but are not necessarily limited thereto. Any tertiary amine having a molecular weight sufficient to have can be preferably used in the composition of the present invention without limitation.

According to one embodiment of the present invention, the content of the tertiary amine is characterized in that it comprises 0.005 to 0.1% by weight relative to the total weight of the total composition.

According to another embodiment of the present invention, the content of the tertiary amine is characterized in that it comprises 0.005 to 0.03% by weight relative to the total weight of the total composition.

 However, it will be appreciated by those skilled in the art that higher tertiary amine content may be required when higher acidity materials are used in the propellant component, and lower contents may be required when lower acidity materials are used. It will be self explanatory. That is, the characteristics of the present invention are not in the content of the tertiary amine, but in the case of neutralizing the acid component with the tertiary amine, it is possible to suppress the promotion of the curing reaction of the bismuth subsalicylate to maintain the proper pot life of the thermosetting solid propellant composition. It was found that the non-volatile tertiary amine has no volatility and reactivity and thus does not affect other properties of the propellant, and thus has been confirmed for the first time that it can be usefully used as an additive in the preparation of the propellant composition. It will be said that all of adjusting the content of the tertiary amine according to the content of the material is included in the scope of the present invention.

The nitrate ester polyether-based thermosetting solid propellant composition according to the present invention includes bismuth subsalicylate as a combustion property improving agent, and a conventional nitrate ester polyether series except that it further includes a tertiary amine as a curing rate control agent. It has the same composition as the lead-free propellant composition.

A conventional nitrate ester polyether (NEPE) -based solid propellant composition is a mixed propellant prepared by mixing an oxidant powder with a high molecular binder, wherein the high molecular binder is polyethylene glycol (PEG) or ethylene oxide- Polyether, such as tetrahydrofuran copolymer ether, means a solid propellant composition containing nitrate as a plasticizer.

In a preferred embodiment, the solid propellant composition of the present invention comprises (i) 4 to 20 parts by weight of polyether as a polymeric binder, (ii) 0.5 to 2 parts by weight of a curing agent, and (iii) 10 to 40 parts by weight of nitrate as a plasticizer. A nitrate ester polyether based thermosetting solid propellant composition comprising (iv) 40 to 80 parts by weight of nitramine as an oxidant and (v) 1 to 5 parts by weight of bismuth subsalicylate as a combustion improving agent, wherein the tertiary amine is It is characterized in that it further comprises.

 In another preferred embodiment, the solid propellant composition of the present invention comprises, in addition to nonvolatile tertiary amines, 20 to 30 weight percent nitrate plasticizer, 55 to 62 weight percent nitramine-based oxidant, 1 to 1.5 weight percent combustion Stabilizers, 1.0 to 4.0 wt% combustion property improving agent, 0.5 to 2.0 wt% stabilizer, and the rest of the polymers (prepolymers and curing agents).

The nitrate plasticizer is nitroglycerin, butane triol trinitrate, trimethylol ethane trinitrate, triethylene glycol dynitrate, diethylene glycol dinitrate, normal butyl nitratoethyl nitramine (n-butyl-nitratoethylnitramine ), And the polymer may be polyethylene glycol, glycidyl azide polymer, polydiethylene glycol adipate, ORP-2, polycaprolactone, or the like.

The combustion property improving agent may be bismuth subsalicylate.

In addition to the above components, the solid propellant composition of the present invention may further include other components conventionally used in the solid propellant composition, such as a curing agent, an oxidizing agent, a combustion characteristic improving agent, a combustion catalyst, a crosslinking reaction catalyst, a stabilizer, and other additives for crosslinking a polymer binder. It may include.

The present invention is also directed to adding a tertiary amine to a nitrate ester polyether series thermosetting solid propellant composition comprising bismuth subsalicylate as a combustion characteristics improving agent to control the rate of viscosity increase of the nitrate ester polyether series thermosetting solid propellant composition. Provide a method.

In the present invention, by adding a very small amount of non-volatile tertiary amine by neutralizing the acid generated during the mixing process of the nitrate ester polyether-based lead-free propellant to control the curing reaction rate of the propellant, Even at 20-25 ° C., the time for maintaining the pot life of the propellant composition can be sufficiently extended. In the present invention, since the mixing process and the casting process of the propellant can be performed at room temperature, general tap water can be used as the cooling water.

The present invention also provides a method for producing a nitrate ester polyether-based thermosetting solid propellant composition comprising adding a tertiary amine during the mixing process for preparing the propellant composition and carrying out the mixing and casting process at room temperature.

According to the present invention there is provided a nitrate ester polyether based thermosetting solid propellant composition comprising a tertiary amine and a method of controlling the cure rate of the propellant.

In the present invention, the mixing and casting process of the propellant can be carried out at room temperature by preventing the rapid increase in viscosity caused by the bismuth compound used as the combustion characteristics improving agent using the tertiary amine as the curing rate adjusting agent as the curing reaction catalyst. The viscosity could be kept low enough.

In the present invention, since the mixing and casting process of the propellant can be performed at room temperature, and the temperature can be maintained at room temperature using general tap water as the cooling water, it is advantageous in that a separate cooling device is not required.

1 is a viscosity rising curve of the propellant with temperature (a: 15 ℃, b: 25 ℃, c: 50 ℃)
Figure 2 is a viscosity increase curve with or without DABCO at 25 ℃ (a: when adding DABCO, b: when not adding DABCO)
3 is a viscosity increase curve according to the addition of the tertiary amine species at 25 ° C. (a: when 0.013% by weight of DABCO is added, b: when 0.015% by weight of DBU is added, c: when 0.02% by weight of DBN is added. )
4 is a viscosity rising curve according to the content of DABCO at 25 ℃ (a: when 0.003% by weight of DABCO, b: 0.013% by weight of DABCO, c: 0.02% by weight of DABCO)
5 is a viscosity increase curve according to the content of DABCO in a propellant to which high acidity RDX is applied at 25 ° C. (a: when 0.02% by weight of DABCO is added, b: 0.04% by weight of DABCO, c: 0.04% by weight of DABCO) If added by weight)

Hereinafter, the present invention will be described in more detail with reference to Examples. However, these examples are only illustrative of the present invention, and the scope of the present invention is not limited to the scope of these examples.

Example

Comparative example

5.9% by weight of polystyrene glycol polymer, curing agent N-3200 [1,3,5-tris (6-isocyanatohexyl) -1,3,5-triazine-2,4,6-trione (1 , 3,5-tris (6-isocyanatohexyl) -1,3,5-triazine-2,4,6-trione) 1.2 wt%, butanetriol trinitrate 22.2 wt%, trimethylolethane trinitrate 7.0 wt% %, 30 wt% HNIW and 29 wt% RDX as nitramine-based oxidant, 0.8 wt% N-methyl para-nitroaniline (NMA), copolymer of acrylonitrile-2hydroxyethyl acrylate as neutral polymeric binder To a mixture of 0.2% by weight, zirconium carbide 1.3% by weight and 0.4% by weight carbon black, 2% by weight of bismuth subsalicylate as a combustion catalyst was added, and then the viscosity of the composition was observed to increase with time and temperature. And the result is shown in FIG. 1 a shows the viscosity rise curve in 15 degreeC, b is 25 degreeC, and 50 degreeC, respectively.

After the mixing of the propellant has been completed, the propellant must have a viscosity of about 20 kilopoise or less for the casting to be carried out smoothly in the mold. 1 a shows that the viscosity of the propellant composition of the comparative example is maintained at 10 kilopoise or less for at least 6 hours at 15 ° C, and FIG. 1 b shows that the viscosity of the propellant composition of the comparative example exceeds 20 kilopoise within 2 hours at 25 ° C. 1 c shows that the propellant composition of the comparative example is not flowable enough to be cast after 10 minutes at 50 ° C. From this, it can be seen that although the composition of the comparative example is capable of casting the propellant at 15 ° C, the casting is impossible at higher temperatures.

Example 1

0.013% by weight of DABCO relative to the total weight of the composition At the same time as addition of hardener Except for the addition, a propellant composition was prepared with the same composition as in Comparative Example, and then the viscosity increase of the composition was observed at 25 ° C. over time, and the result is shown in FIG. 2 b together shows the viscosity rising curve at 25 ° C. of the composition according to the comparative example for comparison with a of FIG. 1.

2a shows that the rate of viscosity rise at 25 ° C. of the composition according to an embodiment of the invention is similar to the rate of viscosity rise at 15 ° C. of the composition according to the comparative example, which is shown in b of FIG. 2. Of propellant compositions according to examples It is an extremely small thing compared with the rate of viscosity increase in 25 degreeC. Therefore, it can be seen that the composition according to the embodiment of the present invention can proceed the mixing and casting process at 25 ℃.

Example 2

A propellant composition was prepared in the same composition as in Example 1, except that 27 wt% of HMX was used instead of 30 wt% of HNIW and 3 wt% of a polymer was used as the nitramine oxidizing agent, and the viscosity with time at 25 ° C. As a result of observing the change, the same viscosity as that shown in FIG. 2A was observed.

In order to maintain the propellant manufacturing process temperature at 15 ° C, it is necessary to maintain the temperature of the cooling water below 15 ° C by using a separate refrigeration unit, but the temperature of 25 ° C may be maintained by using general tap water as the cooling water. have.

The curing reaction rate can be controlled by the addition of very small amounts of DABCO in Examples 1 and 2 above because the acidic material produced from bismuth subsalicylate is neutralized by DABCO.

Example  3

The same results as in Examples 1 and 2 were obtained even when using DBN or DBU instead of DABCO.

Figure 3 is a comparison of the rate of viscosity increase at 25 ℃ of the composition according to an embodiment of the present invention, Figure 3 a is added DABCO 0.013% by weight, Figure 3b is added to DB5 0.015% by weight DBU 3 c shows the addition of 0.02% by weight of DBN. 3 a to c show that the tendency of viscosity increase when three kinds of tertiary amines are added respectively is similar.

Figure 4 shows the change over time of the propellant viscosity with the change in the content of DABCO. FIG. 4A shows the addition of 0.003% by weight of DABCO, b of FIG. 4 shows the addition of 0.013% by weight of DABCO, and c of FIG. 4 shows the addition of 0.02% by weight of DABCO. In FIG. 4A, the viscosity is rapidly increased after 4 hours, whereas in FIG. 4C, there is almost no change in viscosity even up to 10 hours. In the case of FIG. 4C, the hardness was lower than that of FIG. 4A or 4B after the curing of the propellant was completed, presumably because the curing reaction did not proceed normally. Therefore, it is considered that the content of DABCO is 0.013% by weight.

Example  4

The same lot as in Example 1, but the production lot of RDX, which is 29% by weight of applied nitramine oxidant, is an example using a different lot. As the lot of RDX was changed, the acidity, which is one of the chemical properties, was also changed. When the acidity was 10 times higher than that of RDX of Example 1, 0.01 wt%, the viscosity of the propellant after the mixing process was increased according to the change of the content of DABCO. Shown in 5A, 5B, and 5C are changes in viscosity increase with respect to the addition of 0.02, 0.03, and 0.04% by weight of DABCO, respectively. In this case, it can be seen that the curing reaction rate can be similarly controlled by using DABCO more than twice as shown in FIG. 4. As can be seen in this example, the use of higher acidity materials in the propellant components indicates that more DABCO content is required to control acidity.

From the above results, it was confirmed that the nonvolatile tertiary amine did not affect other properties of the propellant because it was not volatile and reactive while maintaining a proper pot life of the thermosetting solid propellant composition. Thus, it has been found that nonvolatile tertiary amines are useful additives in preparing propellant compositions.

Claims (3)

A nitrate ester polyether-based thermosetting solid propellant composition comprising bismuth subsalicylate as a burn improver, the composition further comprising a tertiary amine.
The composition of claim 1, wherein the tertiary amine is included in an amount of 0.005 to 0.1 wt% based on the total weight of the total composition.
The method of claim 1, wherein the tertiary amine is 1,4-diazabicyclo [2.2.2] octane, 1,5-diazabicyclo [4.3.0] non-5-ene and 1,8-diazabicyclo [5.4.0] A composition characterized in that it is selected from the group consisting of Undes-7-ene.

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