JPH0475877B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Field of Application) The present invention relates to composite propellants. Specifically, the present invention relates to a high-energy binder-type composite propellant containing a binder whose main component is a specific polyether having a methyl azide group in the side chain, and which has improved physical properties without deteriorating the combustion properties. (Prior art) Composite propellants have a composition in which the main components are an oxidizing agent and a binder that serves as a matrix and fuel, with metal powder added as a combustion improver if necessary, and it has excellent combustion characteristics. It is widely used as a propellant for high-performance rocket motors due to its physical properties and properties. As typical oxidizing agents, ammonium perchlorate, nitramine, ammonium nitrate, etc. are used, and as binders, polybutadiene, polyurethane, etc. are used. Also, aluminum powder or the like is used as a combustion aid. Improvement in the combustion performance of composite solid propellants can be achieved by using components with excellent combustion characteristics for each of these components. However, in practical terms, oxidizing agents and combustion improvers are limited to the above-mentioned types due to restrictions such as their stability, stability, and toxicity. Therefore, in recent years, research has been actively conducted on high-energy binder type composite solid propellants, which have improved combustion performance by containing binder components with high energy content. For example, propellants containing binders in which high-energy plasticizers such as nitroplasticizers are added to polyurethane, which is a common binder component, are being considered; however, in this case, as the amount of plasticizer increases, the propellant There was a problem that the physical properties of the material deteriorated. Therefore, recently, propellants in which the prepolymer itself, which is the main component of the binder and has functional groups, has a high energy content have been studied. As a representative prepolymer, polyethers with terminal hydroxyl groups having azide groups have been studied, and among them, aliphatic polyethers with terminal hydroxyl groups having methyl azide groups in the side chains, which are disclosed in US Pat. No. 4,268,450, are practically It is viewed as promising. The polyether is represented by the following general formula. Here, X is from 10 to 60. This polyether has the following advantages and characteristics when viewed as a prepolymer for a propellant binder. (1) High heat of formation. (2) High density. (3) High nitrogen content. It has also been confirmed that it has far superior stability and safety compared to conventional organic azides. Here, regarding (1), among the combustion characteristics of the propellant, it contributes to an increase in specific impulse, and (2) similarly leads to an increase in density and specific impulse. (3) When the binder is decomposed and burned, a large amount of _N2 gas is generated, which contributes to increasing the specific impulse of the propellant, and the proportion of carbon and hydrogen atoms is small compared to other binders. Therefore, the amount of oxidizing agent in the propellant, that is, the proportion of solid content, can be reduced, and the viscosity of the propellant slurry is therefore reduced, which contributes to improving the productivity of the propellant. (Problems to be Solved by the Invention) However, when used as a propellant binder as described above, the polyether represented by the formula () has very excellent characteristics in terms of combustion characteristics and manufacturability. A major problem was that the physical properties at low temperatures were extremely poor. As a result of intensive research in consideration of the above-mentioned problems, the present inventors have discovered a polyether in which a specific amount of ethylene oxide and/or propylene oxide is added to the main chain of the polyether represented by the above formula (). The present invention was completed based on the finding that a propellant containing ether as a binder has significantly improved low-temperature physical properties without reducing its combustion performance. (Means for Solving the Problems) That is, the present invention provides a high energy binder type composite propellant in which the main component of the binder is a terminal hydroxyl group aliphatic polyether having a methyl azide group in the side chain. Polyether has the general formula (In the formula, n represents 10 to 35, and m+l represents 1 to 35.)
The present invention relates to a high energy binder type composite propellant characterized by the following: Here, if n is less than 10 in the general formula (), elongation among the physical properties of the propellant will decrease. If n exceeds 35, among the physical characteristics,
Since the tensile strength decreases and the viscosity of the polyether increases, the productivity of the propellant tends to deteriorate. Preferably, n=14-30. Moreover, if m+l exceeds 35, the combustion performance of the propellant will deteriorate. Preferably, m+l ranges from n×0.2 to n×1.0. The polyether represented by the general formula () is preferably contained in the propellant in an amount of 7 to 30% by weight, and if it is less than 7% by weight or exceeds 30% by weight, the propellant may More preferably, the specific impulse is in the range of 10 to 25% by weight. A method for synthesizing polyether represented by general formula () will be exemplified. Examples of reaction initiation include ethylene glycol, propylene glycol, α-monochloro-
Epichlorohydrin and ethylene oxide or propylene oxide, or epichlorohydrin, ethylene oxide, and propylene oxide are subjected to an addition reaction in a system in which a reaction catalyst is dissolved in diols made of hydrin and their polymers, and a chloromethyl group is added to the side chain. Synthesize an aliphatic polyether with a terminal hydroxyl group. Next, by reacting the polyether and sodium azide in a solvent at a predetermined temperature and time, the general formula ()
A polyether represented by is obtained. The obtained polyether was subjected to various analyzes such as elemental analysis, infrared absorption analysis, molecular weight measurement, and chemical analysis of hydroxyl groups.
It is confirmed that it has a structure represented by the general formula (). In addition to the above-mentioned polyether, the binder in the propellant of the present invention includes a crosslinking agent and a curing agent, and if necessary, a plasticizer, an oxidizing agent, a binder that imparts adhesion to the binder, a curing catalyst, an anti-aging agent, etc. It is composed of additives. Examples of the crosslinking agent include trimethylolpropane (TMP) and polyfunctional polyols having trifunctionality or more, such as polyether triol and polyester triol, and preferably TMP and trifunctional polyols having a molecular weight of 1000 or less. Examples of the curing agent include diisocyanate compounds such as hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), and tolylene diisocyanate.
HMDI or IPDI. As a plasticizer, dioctyl adipate (D-
In addition to esters such as OA), dioctyl sebacate (DOS), diisodecyl adipate (DIDA), and isodecyl pelagonate, 1,2,4 butanetriol trinitrate (BTTN), trimethylolethane trinitrate (TMETN) ), triethylene glycol dinitrate (TEGDN)
Use nitro plasticizers such as As a binder, bisisophthaloyl 1-(2
Aziridine series such as methyl) aziridine (HX-752, manufactured by 3M), reaction products of tetraethylenepentamine and acrylonitrile (TEPAN or HX-
879, manufactured by 3M Company) Amine-based products such as the reaction product of tetraethylenepentamine with acrylonitrile and glycidol (TEPANOL or HX-878, manufactured by 3M Company), hydantoin-based products such as dihydroxyethyl-5,5-dimethylhydantoin (DHE), and Silane coupling agent (A-1100, manufactured by Nippon Unicar Co., Ltd.)
etc. As the curing catalyst, for example, organic tin compounds such as dibutyltin dilaurate (DBTDL) and dibutyltin di(2-ethylhexoate) and amines such as triethylenediamine are used. Examples of anti-aging agents include 2,2'-methylene-bis(4-methyl-6-tert-butylphenol), a reaction product of phenyl-β-naphthylamine and diphenylamine with acetone (Nonflex BA, manufactured by Seiko Kagaku Co., Ltd.). ) etc. When producing composite propellants, the binder described above is typically used in an amount of 10 to 35% by weight, an oxidizing agent is added thereto, and, if necessary, combustion improvers and combustion modifiers are added to adjust the performance. Oxidizing agents typically include ammonium perchlorate (AP), cyclotetramethylenetetranitramine (HMX), cyclotrimethylenetrinitramine (RDX), triaminoguanidine nitrate (TAGN), and ammonium nitrate (AN). used. Note that AP and AN may be coated with a thermosetting resin such as epoxy resin or a thermoplastic resin such as polyvinyl chloride in order to prevent the reaction between their moisture content and isocyanate, which is a curing agent. As combustion improvers, metal powders such as aluminum and boron are used; as combustion modifiers, iron oxide, ferrocene derivatives, carborane derivatives, lead salts,
Carbon etc. are used. The proportions of each component of the high energy binder type composite propellant of the present invention are generally as follows. The binder is 10 to 35% by weight, the oxidizing agent is 65 to 90% by weight, and if necessary, 5 to 20% by weight of a combustion improver and 1 to 10% by weight of various additives such as a combustion modifier are included. The high-energy binder type composite propellant of the present invention can be obtained using raw materials corresponding to the above-mentioned components and by a conventional manufacturing method. (Operations and Effects of the Invention) The high-energy binder type composite propellant of the present invention has lower combustion characteristics compared to the conventionally known propellant containing polyether represented by the formula () and possessing high combustion performance. The physical properties at low temperatures are significantly improved. It has been proven by Examples and Comparative Examples that this effect is due to the action of a polymer obtained by addition polymerization of at least one of ethylene oxide and propylene oxide to the main chain of the polyether represented by the formula (). (Examples) Hereinafter, the present invention will be specifically explained using examples. Example 1 (Synthesis of polyether represented by general formula ()) First, a polyether to be the main component of the binder was manufactured as follows. Add 62.0 g of ethylene glycol and 10.5 g of ether complex salt of boron trifluoride to an airtight reaction vessel, and then add epichlorohydrin (ECH) and ethylene oxide (EO) to ECH:EO=10:5.5 (molar ratio).
Put 2570g of the mixture in the ratio of 30 into a reaction container.
The addition reaction was carried out under heating at a temperature of 0.degree. C. to 60.degree. C. and a pressure of 0.5 to 5.0 kg/ ^cm.sup.2 in a nitrogen gas atmosphere. The reaction product was then heated to 70-90°C and unreacted ECH and EO were removed under reduced pressure. Furthermore, the catalyst was neutralized with a 10% aqueous sodium carbonate solution to bring the pH to 5-7. Thereafter, the mixture was heated to 80 to 100°C, water was removed under reduced pressure, and purified by filtration to obtain 2500 g of ECH-EO copolymer as a pale yellow transparent liquid, which had a hydroxyl value of 46.8. Next, 1500 g of the ECH-EO copolymer and 1500 g of sodium azide were reacted in DMF at 100° C. for 72 hours. Thereafter, the mixture was cooled to room temperature, diluted with methylene chloride, and washed with distilled water to remove DMF and unreacted sodium azide. After water was removed using sodium sulfate, the mixture was filtered and methylene chloride was removed under reduced pressure to obtain 1300 g of amber transparent liquid polyether. (Physical properties of polyether) The liquid prepolymer obtained by the above method was found to have the general formula () with n = 20, m = 11, l = 0, and it was confirmed that it was a terminal hydroxyl group fatty polyether having a methyl azide group in the side chain. The analytical values of this polyether are shown below. Elemental analysis results: C39.6 H5.9 N33.8 (wt%) Molecular weight: 2500 Infrared absorption: Confirmed absorption of _N3 groups at 2100 cm ^-1 Hydroxyl value: 45.0 Number of functional groups: 2 Density: 1.3 g/m ³ ( Production and physical properties of propellant of the present invention) Next, 2.06 parts of trimethylolpropane (TMP), which is a crosslinking agent, was added to 85.81 parts by weight of the above polyether.
parts by weight, 0.01 parts by weight of dibutyltin dilaurate as a curing catalyst and 1.72 parts by weight of a reaction product of tetraethylene pentamine, acrylonitrile and glycidol (TEPANOL) as a binder, and after mixing, perchloric acid as an oxidizing agent was added to the mixture. A predetermined amount of ammonium was charged, heated to 60°C, and mixed under vacuum for 30 minutes. Next, 10.4 parts by weight of hexamethylene diisocyanate (HMDI) as a curing agent was added, and vacuum mixing was further performed for 10 minutes to obtain a slurry-like mixture. This mixture was poured into a predetermined molding container under vacuum, and after degassing, it was cured at 60° C. for 7 days to obtain the propellant of the present invention. The viscosity at 60° C. of the slurry-like mixture immediately after vacuum mixing was measured using an E-type viscometer. The binder composition and propellant composition are shown in Table 1, and the viscosity is shown in Table 2. Further, the tensile properties and combustion properties were measured using the above propellant by the methods shown below, and the obtained results are shown in Table 2. (Tensile properties) A tensile test piece specified by the Propellant Properties Committee was prepared from the above propellant, and a tensile test was performed at a tensile speed of 50 mm/min and a test temperature of 20°C and -30°C, and the maximum stress ( Tensile strength), strain at maximum stress (elongation), and elastic modulus were determined. The tensile test specimen specified by the Propellant Drug Properties Committee has a total length of 125 mm, a width of 25 mm at both ends, and a thickness with a central straight section of 50 mm length and 10 mm width between both ends.
This is a 10mm test piece. (Combustibility characteristics) A propellant having a cylindrical shape with a diameter of 80 mm and a length of 140 mm and an inner hole of 40 mm in diameter in the center was prepared, and a drug trunk was prepared by coating the outer peripheral side with epoxy resin. Load this propellant into a standard rocket motor chamber with a total internal diameter of 84 mm, adjust the nozzle throat diameter so that the pressure is 50 Kgf/ ^m2 , and use a normal small rocket motor combustion stand device to determine the propellant ratio. The thrust and burning rate were measured. Note that the aperture ratio of the nozzle is 6. Examples 2 to 29 In the same manner as in Example 1, polyethers represented by the general formula () were synthesized by varying the numbers of n, m, and l. In addition, the propellants of the present invention with different amounts of binder, types and blending ratios of binder components, types and blending ratios of oxidizers, blending ratios of combustion modifiers, and blending ratios of combustion improvers were formulated, and the propellants of Example 1 and Slurry viscosity, tensile properties, and combustion properties were measured in exactly the same manner. The binder composition and propellant composition are shown in Table 1, and the slurry viscosity, tensile strength, and combustion characteristics are shown in Table 2.

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[Table] Each symbol in the binder composition and propellant composition in Table 1 indicates the following substances. TMP: Trimethylolpropane HMDI: Hexamethylene diisocyanate DBTDL: Dibutyltin dilaurate TEPANOL: Reaction product of tetraethylenepentamine, acrylonitrile, and glycidol (HX-878, manufactured by 3M) DHE: Dihydroxyethyl 5,5 dimethylhydantoin BTTN: 1 , 2,4 butanetriol trinitrate DOA: dioctyl adipate HMX: cyclotetramethylenetetranitramine RDX: cyclotrimethylene trinitramine TAGN: triaminoguanidine nitrate

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【table】

[Table] Comparative Examples 1 to 13 Propellants were prepared in the same manner as in Example 1 by using conventional polyether represented by the general formula () and changing the composition of the binder and propellant. Slurry viscosity, tensile strength, aging characteristics, and combustion characteristics were measured. The composition is shown in Table 3, and the various measurement results are shown in Table 4.

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【table】

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[Table] In Examples 1 to 17 and Comparative Example 1, the binder amount was 20% by weight, and the amount of ammonium perchlorate as the oxidizing agent was 20% by weight.
It is 80% propellant by weight. Here, in Examples 1 to 17, the elongation at a low temperature of -30°C (strain at maximum stress) tends to decrease as the number of m or l in polyether () decreases, but in comparison When compared with Example 1, both values are significantly larger, and it is clear that the propellant of the present invention has significantly improved low-temperature elongation. Further, when comparing the combustion characteristics, it is clear that the propellants of Examples 1 to 17 are equivalent to the propellant of Comparative Example 1, although there are some differences in size. Further, Examples 18 to 29 are propellants in which the blending composition of the binder and propellant is changed, and Comparative Examples 2 to 13 correspond to each composition. Here again, if we compare the Examples and Comparative Examples, it is clear that the elongation of the propellant of the present invention shown in the Examples at -30°C is significantly increased compared to the Comparative Examples. be. Furthermore, it is clear that the combustion characteristics are the same in both the Examples and Comparative Examples. That is, the propellant of the present invention does not reduce combustion characteristics and has improved physical properties at low temperatures.

Claims (1)

[Scope of Claims] 1. A high-energy binder type composite propellant in which the main component of the binder is a terminal hydroxyl group aliphatic polyether having a methyl azide group in the side chain, wherein the terminal hydroxyl group aliphatic polyether has the general formula (In the formula, n represents 10 to 35, and m+l represents 1 to 35.) A high energy binder type composite propellant, characterized in that it is represented by the formula: 2. The high-energy binder type composite propellant according to claim 1, wherein the terminal hydroxyl group aliphatic polyether having a methyl azide group in the side chain accounts for 7 to 30% by weight of the propellant.