GB2257968A - Preparation of composite double base propellants - Google Patents
Preparation of composite double base propellants Download PDFInfo
- Publication number
- GB2257968A GB2257968A GB8413649A GB8413649A GB2257968A GB 2257968 A GB2257968 A GB 2257968A GB 8413649 A GB8413649 A GB 8413649A GB 8413649 A GB8413649 A GB 8413649A GB 2257968 A GB2257968 A GB 2257968A
- Authority
- GB
- United Kingdom
- Prior art keywords
- process according
- base powder
- base
- propellant
- crosslinking agent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000003380 propellant Substances 0.000 title claims abstract description 42
- 239000002131 composite material Substances 0.000 title claims abstract description 11
- 238000002360 preparation method Methods 0.000 title description 3
- 238000000034 method Methods 0.000 claims abstract description 48
- 239000000843 powder Substances 0.000 claims abstract description 38
- 238000005266 casting Methods 0.000 claims abstract description 31
- 239000002904 solvent Substances 0.000 claims abstract description 21
- 229920001228 polyisocyanate Polymers 0.000 claims abstract description 18
- 239000005056 polyisocyanate Substances 0.000 claims abstract description 18
- 239000003431 cross linking reagent Substances 0.000 claims abstract description 14
- 238000011065 in-situ storage Methods 0.000 claims abstract description 9
- 239000000203 mixture Substances 0.000 claims description 20
- 239000000020 Nitrocellulose Substances 0.000 claims description 13
- 229920001220 nitrocellulos Polymers 0.000 claims description 13
- XTFIVUDBNACUBN-UHFFFAOYSA-N 1,3,5-trinitro-1,3,5-triazinane Chemical group [O-][N+](=O)N1CN([N+]([O-])=O)CN([N+]([O-])=O)C1 XTFIVUDBNACUBN-UHFFFAOYSA-N 0.000 claims description 11
- BSPUVYFGURDFHE-UHFFFAOYSA-N Nitramine Natural products CC1C(O)CCC2CCCNC12 BSPUVYFGURDFHE-UHFFFAOYSA-N 0.000 claims description 11
- POCJOGNVFHPZNS-UHFFFAOYSA-N isonitramine Natural products OC1CCCCC11CNCCC1 POCJOGNVFHPZNS-UHFFFAOYSA-N 0.000 claims description 11
- POCJOGNVFHPZNS-ZJUUUORDSA-N (6S,7R)-2-azaspiro[5.5]undecan-7-ol Chemical compound O[C@@H]1CCCC[C@]11CNCCC1 POCJOGNVFHPZNS-ZJUUUORDSA-N 0.000 claims description 10
- 239000000028 HMX Substances 0.000 claims description 9
- UZGLIIJVICEWHF-UHFFFAOYSA-N octogen Chemical compound [O-][N+](=O)N1CN([N+]([O-])=O)CN([N+]([O-])=O)CN([N+]([O-])=O)C1 UZGLIIJVICEWHF-UHFFFAOYSA-N 0.000 claims description 9
- 238000002485 combustion reaction Methods 0.000 claims description 8
- 125000005442 diisocyanate group Chemical group 0.000 claims description 7
- 239000003054 catalyst Substances 0.000 claims description 6
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 6
- 239000000654 additive Substances 0.000 claims description 4
- 229920000728 polyester Polymers 0.000 claims description 4
- 229920000570 polyether Polymers 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- 239000004721 Polyphenylene oxide Substances 0.000 claims 2
- SNIOPGDIGTZGOP-UHFFFAOYSA-N Nitroglycerin Chemical compound [O-][N+](=O)OCC(O[N+]([O-])=O)CO[N+]([O-])=O SNIOPGDIGTZGOP-UHFFFAOYSA-N 0.000 abstract description 13
- 229960003711 glyceryl trinitrate Drugs 0.000 abstract description 13
- 239000000006 Nitroglycerin Substances 0.000 abstract description 11
- URAYPUMNDPQOKB-UHFFFAOYSA-N triacetin Chemical compound CC(=O)OCC(OC(C)=O)COC(C)=O URAYPUMNDPQOKB-UHFFFAOYSA-N 0.000 abstract description 8
- 239000004014 plasticizer Substances 0.000 abstract description 7
- 239000003381 stabilizer Substances 0.000 abstract description 5
- 235000013773 glyceryl triacetate Nutrition 0.000 abstract description 4
- 239000001087 glyceryl triacetate Substances 0.000 abstract description 4
- 229960002622 triacetin Drugs 0.000 abstract description 4
- IPPYBNCEPZCLNI-UHFFFAOYSA-N trimethylolethane trinitrate Chemical compound [O-][N+](=O)OCC(C)(CO[N+]([O-])=O)CO[N+]([O-])=O IPPYBNCEPZCLNI-UHFFFAOYSA-N 0.000 abstract description 3
- RDLIBIDNLZPAQD-UHFFFAOYSA-N 1,2,4-butanetriol trinitrate Chemical compound [O-][N+](=O)OCCC(O[N+]([O-])=O)CO[N+]([O-])=O RDLIBIDNLZPAQD-UHFFFAOYSA-N 0.000 abstract description 2
- WCHSUHMPMUTNKY-UHFFFAOYSA-N 1-nitrooxypropyl nitrate Chemical compound [O-][N+](=O)OC(CC)O[N+]([O-])=O WCHSUHMPMUTNKY-UHFFFAOYSA-N 0.000 abstract description 2
- PZIMIYVOZBTARW-UHFFFAOYSA-N centralite Chemical compound C=1C=CC=CC=1N(CC)C(=O)N(CC)C1=CC=CC=C1 PZIMIYVOZBTARW-UHFFFAOYSA-N 0.000 abstract description 2
- XIFJZJPMHNUGRA-UHFFFAOYSA-N n-methyl-4-nitroaniline Chemical compound CNC1=CC=C([N+]([O-])=O)C=C1 XIFJZJPMHNUGRA-UHFFFAOYSA-N 0.000 abstract description 2
- YLKFDHTUAUWZPQ-UHFFFAOYSA-N N-Nitrosodi-n-propylamine Chemical compound CCCN(N=O)CCC YLKFDHTUAUWZPQ-UHFFFAOYSA-N 0.000 abstract 1
- -1 TRENO Chemical compound 0.000 abstract 1
- FJWGYAHXMCUOOM-QHOUIDNNSA-N [(2s,3r,4s,5r,6r)-2-[(2r,3r,4s,5r,6s)-4,5-dinitrooxy-2-(nitrooxymethyl)-6-[(2r,3r,4s,5r,6s)-4,5,6-trinitrooxy-2-(nitrooxymethyl)oxan-3-yl]oxyoxan-3-yl]oxy-3,5-dinitrooxy-6-(nitrooxymethyl)oxan-4-yl] nitrate Chemical compound O([C@@H]1O[C@@H]([C@H]([C@H](O[N+]([O-])=O)[C@H]1O[N+]([O-])=O)O[C@H]1[C@@H]([C@@H](O[N+]([O-])=O)[C@H](O[N+]([O-])=O)[C@@H](CO[N+]([O-])=O)O1)O[N+]([O-])=O)CO[N+](=O)[O-])[C@@H]1[C@@H](CO[N+]([O-])=O)O[C@@H](O[N+]([O-])=O)[C@H](O[N+]([O-])=O)[C@H]1O[N+]([O-])=O FJWGYAHXMCUOOM-QHOUIDNNSA-N 0.000 description 11
- 229940079938 nitrocellulose Drugs 0.000 description 11
- RRAMGCGOFNQTLD-UHFFFAOYSA-N hexamethylene diisocyanate Chemical compound O=C=NCCCCCCN=C=O RRAMGCGOFNQTLD-UHFFFAOYSA-N 0.000 description 10
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 6
- 229910052802 copper Inorganic materials 0.000 description 5
- 239000010949 copper Substances 0.000 description 5
- 150000002148 esters Chemical class 0.000 description 5
- RUKISNQKOIKZGT-UHFFFAOYSA-N 2-nitrodiphenylamine Chemical compound [O-][N+](=O)C1=CC=CC=C1NC1=CC=CC=C1 RUKISNQKOIKZGT-UHFFFAOYSA-N 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical class [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- 159000000032 aromatic acids Chemical class 0.000 description 3
- VNZQQAVATKSIBR-UHFFFAOYSA-L copper;octanoate Chemical compound [Cu+2].CCCCCCCC([O-])=O.CCCCCCCC([O-])=O VNZQQAVATKSIBR-UHFFFAOYSA-L 0.000 description 3
- 229960004643 cupric oxide Drugs 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- WXTMDXOMEHJXQO-UHFFFAOYSA-N 2,5-dihydroxybenzoic acid Chemical compound OC(=O)C1=CC(O)=CC=C1O WXTMDXOMEHJXQO-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 238000004132 cross linking Methods 0.000 description 2
- 239000012948 isocyanate Substances 0.000 description 2
- 150000002513 isocyanates Chemical class 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- AGCQZYRSTIRJFM-UHFFFAOYSA-N triethylene glycol dinitrate Chemical compound [O-][N+](=O)OCCOCCOCCO[N+]([O-])=O AGCQZYRSTIRJFM-UHFFFAOYSA-N 0.000 description 2
- QUAMCNNWODGSJA-UHFFFAOYSA-N 1,1-dinitrooxybutyl nitrate Chemical compound CCCC(O[N+]([O-])=O)(O[N+]([O-])=O)O[N+]([O-])=O QUAMCNNWODGSJA-UHFFFAOYSA-N 0.000 description 1
- HWZIRFCGHAROOI-UHFFFAOYSA-N 2,4,6-trihydroxybenzoic acid;hydrate Chemical compound O.OC(=O)C1=C(O)C=C(O)C=C1O HWZIRFCGHAROOI-UHFFFAOYSA-N 0.000 description 1
- OBETXYAYXDNJHR-UHFFFAOYSA-N 2-Ethylhexanoic acid Chemical compound CCCCC(CC)C(O)=O OBETXYAYXDNJHR-UHFFFAOYSA-N 0.000 description 1
- LLVFMJQPUWTQTM-UHFFFAOYSA-M 2-carboxy-5-hydroxyphenolate;lead(2+) Chemical compound [Pb+2].OC1=CC=C(C([O-])=O)C(O)=C1 LLVFMJQPUWTQTM-UHFFFAOYSA-M 0.000 description 1
- SZJXEIBPJWMWQR-UHFFFAOYSA-N 2-methylpropane-1,1,1-triol Chemical compound CC(C)C(O)(O)O SZJXEIBPJWMWQR-UHFFFAOYSA-N 0.000 description 1
- 239000005751 Copper oxide Substances 0.000 description 1
- 239000005058 Isophorone diisocyanate Substances 0.000 description 1
- AGUIVNYEYSCPNI-UHFFFAOYSA-N N-methyl-N-picrylnitramine Chemical compound [O-][N+](=O)N(C)C1=C([N+]([O-])=O)C=C([N+]([O-])=O)C=C1[N+]([O-])=O AGUIVNYEYSCPNI-UHFFFAOYSA-N 0.000 description 1
- KXBFLNPZHXDQLV-UHFFFAOYSA-N [cyclohexyl(diisocyanato)methyl]cyclohexane Chemical compound C1CCCCC1C(N=C=O)(N=C=O)C1CCCCC1 KXBFLNPZHXDQLV-UHFFFAOYSA-N 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- CNVULGHYDPMIHD-UHFFFAOYSA-L bis[(2-hydroxybenzoyl)oxy]lead Chemical compound [Pb+2].OC1=CC=CC=C1C([O-])=O.OC1=CC=CC=C1C([O-])=O CNVULGHYDPMIHD-UHFFFAOYSA-L 0.000 description 1
- SHZIWNPUGXLXDT-UHFFFAOYSA-N caproic acid ethyl ester Natural products CCCCCC(=O)OCC SHZIWNPUGXLXDT-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 150000001879 copper Chemical class 0.000 description 1
- 229910000431 copper oxide Inorganic materials 0.000 description 1
- BERDEBHAJNAUOM-UHFFFAOYSA-N copper(I) oxide Inorganic materials [Cu]O[Cu] BERDEBHAJNAUOM-UHFFFAOYSA-N 0.000 description 1
- KRFJLUBVMFXRPN-UHFFFAOYSA-N cuprous oxide Chemical compound [O-2].[Cu+].[Cu+] KRFJLUBVMFXRPN-UHFFFAOYSA-N 0.000 description 1
- 229940112669 cuprous oxide Drugs 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- UQLDLKMNUJERMK-UHFFFAOYSA-L di(octadecanoyloxy)lead Chemical compound [Pb+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O UQLDLKMNUJERMK-UHFFFAOYSA-L 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- NIMLQBUJDJZYEJ-UHFFFAOYSA-N isophorone diisocyanate Chemical compound CC1(C)CC(N=C=O)CC(C)(CN=C=O)C1 NIMLQBUJDJZYEJ-UHFFFAOYSA-N 0.000 description 1
- DSSXKBBEJCDMBT-UHFFFAOYSA-M lead(2+);octanoate Chemical compound [Pb+2].CCCCCCCC([O-])=O DSSXKBBEJCDMBT-UHFFFAOYSA-M 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- RUELTTOHQODFPA-UHFFFAOYSA-N toluene 2,6-diisocyanate Chemical compound CC1=C(N=C=O)C=CC=C1N=C=O RUELTTOHQODFPA-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
- C06B45/04—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive
- C06B45/06—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive the solid solution or matrix containing an organic component
- C06B45/10—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive the solid solution or matrix containing an organic component the organic component containing a resin
- C06B45/105—The resin being a polymer bearing energetic groups or containing a soluble organic explosive
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B25/00—Compositions containing a nitrated organic compound
- C06B25/18—Compositions containing a nitrated organic compound the compound being nitrocellulose present as 10% or more by weight of the total composition
- C06B25/24—Compositions containing a nitrated organic compound the compound being nitrocellulose present as 10% or more by weight of the total composition with nitroglycerine
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B25/00—Compositions containing a nitrated organic compound
- C06B25/34—Compositions containing a nitrated organic compound the compound being a nitrated acyclic, alicyclic or heterocyclic amine
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Dispersion Chemistry (AREA)
- Molecular Biology (AREA)
- Crystallography & Structural Chemistry (AREA)
- Emergency Medicine (AREA)
- Polyurethanes Or Polyureas (AREA)
- Moulding By Coating Moulds (AREA)
Abstract
A composite double base propellant is provided by the in situ casting method, at least one polyisocyanate crosslinking agent being introduced together with the casting solvent into the base powder. The propellant may include nitroglycerin, TMETN, TRENO, BTTN, propanediol dinitrate; a plasticiser such as triacetin, and a stabiliser, such as NDPA, centralite or N-methyl-para-nitroaniline.
Description
Preparation of composite double
base propellants
This invention is concerned with the preparation of composite double base propellants by the in situ casting method, and with the propellants so obtained.
The in situ casting method for making double base propellants comprises placing a base powder comprising nitrocellulose and a stabiliser and, optionally, a nitric ester, an oxidizing and/or reducing solid charge, and/or a combustion catalyst system, into a mould, introducing a casting solvent comprising a nitric ester, a plasticiser, and a stabiliser,into the mould, and then curing the mixture, normally at an elevated temperature.
This method is briefly described, and contrasted with the alternative method of making double base propellants known as the "scurry casting" or "global" method, in
U.S. Patent 4,080,411.
There is a requirement to improve the mechanical properties of double base propellants made by the in situ casting method, particularly those which are highly plasticised and which include inorganic or organic charges.
Double base propellants may be made in two different physical forms:
(i) so-called "moulded-bonded" charges in which the propellant is in the form of a unitary moulded block.
Such compositions must be highly plasticised and in this case the purpose of improving the mechanical properties is to enhance the maximum stress (Sm) which the propellant can withstand in the hot state, while retaining a high maximum elongation (Em) in the cold state. Increasing the degree of plasticisation of such propellants improves their ballistic performance (specific pulse, volume specific pulse); for example in a typical composition the replacement of 5% of nitrocellulose in the base powder by 5% of nitroglycerin (which acts as a plasticiser) increases the specific pulse by 2 sec.
(ii) free grains. In this case, the purpose of improving the mechanical properties is to enhance mechanical strength in the hot state.
We have now found that the mechanical properties of double base propellants made by the in situ casting method can be substantially improved by introducing at least one polyisocyanate crosslinking agent into the base powder together with the casting solvent.
According to the present invention, therefore, there is provided a process of preparing a composite double base propellant by the in situ casting method, in which at least one polyisocyanate crosslinking agent is introduced together with the casting solvent into the base powder.
The polyisocyanate crosslinking agent may be added to the casting solvent simultaneously with the introduction of the latter into the mould containing the base powder, or it may be mixed with the casting solvent prior to the introduction of the latter. In both cases, it is important that the casting solvent should be substantially water-free; in particular, it is preferred that the casting solvent should contain less than 0.1% by weight of water. If a mixture of the casting solvent and the polyisocyanate crosslinking agent is to be stored for any length of time prior to use, it is necessary to take rigorous precautions to protect the mixture from any source of moisture.
As already mentioned, casting solvents for use in the in situ casting method comprise a nitric ester, for example, nitroglycerin, trimethylolethane trinitrate (TMETN), triethyleneglycol dinitrate (TRENo), 1,2,4- butanetriol trinitrate (BTTN), or propanediol dinitrate, or a mixture of two or more thereof (of which nitroglycerine is preferred); a non-energetic plasticiser, for example triacetin; and a stabiliser, for example 2-nitro-diphenylamine (2-NDPA), Centralite or N-methylpara-nitroaniline. The preferred casting solvent compositions are within the following ranges, by weight:
nitric ester 72 to 83%
non-energetic plasticiser 27.5 to 16%
stabilizer 0.5 to 1%
Nitrocellulose includes a number of free hydroxyl groups and it is with such hydroxyl groups that the isocynanate functions react.
Depending on the results required, the quantity of polyisocyanate to be added to the casting solvent, and thus finally to be incorporated in the propellant, is directly related to the quantity of nitrocellulose present in the base powder. It is preferred to use such a quantity of polyisocyanate that the ratio of NC0 groups to free OH equivalents present in the nitrocellulose is from 0.015 to 0.2, and more preferably from 0.03 to 0.15.
It is generally preferred to use bi-functional polyisocyanates, but polyisocyanates of higher functionality can also be used. Suitable diisocyanates include, for example, 2,4- and 2,6-toluene-diisocyanate (TDI), 1-methyl-2,4- and 2,6-cyclohexane-diisocyanate, 4,4'dicyclohexylmethane-diisocyanate, isophorone-diisocyanate, 1,6-hexane-diisocyanate (HMDI), 2,2,4-trimethyl-1,6-hexanediisocyanate, the base adducts of, for example, 1,6-hexanediisocyanate and their mixtures, 4,4',4"-triphenyl- methane-triisocyanate, and the adduct of 1,1 ,1-tri- hydroxymethylpropane and 1,6-hexane-diisocyanate.
Aliphatic diisocyanates are generally preferred because of their lower reaction rates to aromatic diisocyanates, but the latter may be used either alone or in admixture with aromatic diisocyanates.
When moulded-bonded propellants are made by the process of the invention, the degree of plasticisation can be increased (as compared with otherwise similar compositions not made with a polyisocyanate) while still obtaining the same, or even improved, mechanical properties. By this means, the energetic level of the propellant can be improved (by using nitroglycerine to increase the degree of plasticisation).
According to an optional feature of the invention, a prepolymer having hydroxyl terminations is incorporated in the base powder. Such an addition substantially improves the elongation of the product, in the cold, without substantially changing the maximum stress in the hot state. This modification is particularly advantageous in the production of moulded-bonded propellants.
The degree of plasticisation referred to herein means the following ratio, by weight, expressed as a percentage:
nitroglycerin + non-energetic plasticiser
nitroglycerin + non-energetic plasticiser + nitro
cellulose + prepolymer (if present)
The degree of plasticisation can be varied by varying the proportion of nitrocellulose in the base powder and/or by varying the proportion of casting solvent, the latter being determined by the mass filling coefficient (Rm %) required.
The mass filling coefficient is given by the following ratio:
mass of base powder
Rm(%) =
mass of propellant
Propellants having a degree of plasticisation as high as 88% can be obtained by the process of the invention.
The addition of a hydroxyl-terminated prepolymer to the base powder reduces the degree of plasticisation, so that if a high degree of plasticisation is required, the proportions of the other relevant constituents must be adjusted. The proportion of hydroxyl-terminated prepolymer, when used, is preferably not more than 5% by weight in order that the propellant should retain good ballistic properties. Preferred prepolymers for this purpose are those based on polyesters and polyethers.
The propellants made by the process of the invention preferably contain a high proportion of oxidizing charges, the latter preferably being nitramines, such as hexogen and octogen or mixtures thereof. The proportion of nitramine may be very high, up to 70% based on the weight of the base powder, subject, of course, to a corresponding adjustment of the nitric ester content so that the degree of plasticisation is not greater than 88%.
In order that propellants containing nitramine should show good ballistic performance, particularly a small pressure exponent, it is preferred that the base powder of such propellants should include combustion catalysts.
We have found that the use of lead inorganic salts for this purpose gives propellants with less satisfactory characteristics when an aromatic polyisocyanate is used in the process of the invention. On the other hand, excellent results are obtained with catalyst systems which comprise, based on the weight of the base powder:
(a) 2 to 5% of a lead aromatic acid salt;
(b) 1 to 4% of a copper aliphatic or aromatic
acid salt, a lead aliphatic acid salt, or
a copper oxide;
(c) 0.05 to 2% of acetylene black (NA) or
benzene black.
Suitable lead salts (a) include, for example, lead salicylate, lead 9-resorcylate, lead 2,5dihydroxybenzoate, and lead 2,4,6-trihydroxy-benzoate.
Suitable copper and lead salts (b) include, for example, copper or lead 2-ethyl-hexanoate, copper or lead octoate, dibasic copper or lead stearate, and copper salts of the aromatic acids mentioned under (a).
Preferred copper oxides (b) are cuprous oxide and cupric oxide.
The total amount of the catalyst system is preferably less than 10% , based on the weight of the base powder.
The base powder may, if desired, contain one or more anti-instability additives and these do not influence the crosslinking process. Such additives are often desirable in order to improve the combustion stability of the propellant and their not having any deleterious effect on the crosslinking is therefore very important.
In order that the invention may be more fully understood, the following examples are given by way of illustration only.
In these Examples (except Example 6), the casting solvent used had the following composition, by weight:
nitroglycerin 78%
triacetin 21%
2-NDPA 1%
A quantity of the polyisocyanate identified in the
Examples was added to this casting solvent so that the
NCO/OH ratio in the final mixture was as shown below.
The method of making the propellant was in each case as follows. The casting solvent, with the polyisocyanate addition, was injected into the lower section of a mould containing the base powder and gelatinisation took place. The gelatinised mixture was cured at about 40"C for a few hours and then baked at from 600 to 650C for a few days, or was subjected to a continuous baking phase.
The base powder compositions specified in the
Examples all additionally included 2% by weight of 2 -NDPA.
The mechanical properties of the resulting propellants were tested and their maximum stresses (Sm) are reported in MPa and their maximum elongations (Em) as %ages.
Example 1
Base powder
Nitrocellulose 21.5
Nitroglycerin 25
Hexogen or octogen 45
Lead B-resorcylate 3
Copper octoate 2
NA 1.5
The mass filling coefficient (Rm%) was 69% and the
NCO/OH ratio was 0.05 (that is, it was necessary to add approximately 0.4 part of diisocyanate to the casting solvent to obtain this NCO/OH ratio). The degree of plasticisation was 76.4%.
The results of testing are given in the table below:
DIISOCYANATE NITRAMINE Sm at 6o0C j Em at-400C I Hexogen 0.4 19 TDI Octogen 0.5 14 Hexogen ,6 18 HMDI Octogen i 0.6 19 Similar compositions, with octogen or hexogen, but without addition of polyisocyanate to the casting solvent, had no detectable Sm at + 600 C.
Example 2
The base powder was the octogen-containing composition of Example 1. Using different amounts of polyisocyanate to give different NCO/OH ratios, the results obtained were as follows:
NCO/OH Sm at 60?C j Em at -400C 0.5 0.6 1 19 0.075 0.6 1 18 0.094 0.5 15 Example 3
The base powder of Example 1 was used, except that 3% by weight of a polyether-polyester prepolymer having hydroxyl terminations was added. The crosslinking agent was HMDI.
The NCO/OH ratio was 0.09,the filling coefficient was 69%, and the degree of plasticisation was 76.4%.
The test results of the resulting propellant were:
Sm at +600C, 0.4; Em at -400C, 30.
Example 4
Base powder
Nitrocellulose 16.5
Nitroglycerin 30
Hexogen 45
Lead p-resorcylate 3
Copper octoate 2
NA 1.5
The diisocyanate used was HMDI, the NCO/OH ratio was 0.05, the filling coefficient was 68,and the degree of plasticisation was 82.3%. The test results were: Sm at +600C, 0.4; Em at -400C, 40; at -50 C, 20.
Example 5
Base powder
Nitrocellulose 21.5
Nitroglycerin 20
Hexogen 50
Lead p-resorcylate 3
Copper octoate 2
NA 1.5
The diisocyanate was HMDI, the NCO/OH ratio was 0.06, the filling coefficient was 72%, and the degree of plasticisation was 73.3%. The test results were:
Sm at +600C, 0.5; Em at -400C, 10.
Example 6
The composition of the casting solvent, by weight, was as follows:
Nitroglycerin 81.5%
Triacetin 17.5%
2-NDPA 1 % The base powder composition, by weight, was
Nitrocellulose 11%
Nitroglycerin 25%
Hexogen 55%
Lead -resorcylate 3%
Cupric oxide 2%
NA 1.5% The diisocyanate used was HMDI, the NCO/OH ratio was 0.08, the mass filling coefficient was 72%, and the degree of plasticisation was 84%. The mechanical characteristics of the propellant obtained were: Sm at 600C, 0.6; Em at -400C, 30.
Example 7
Front combustion propellants 90 mm in diameter and 90 mm in length and prepared as described in Example 1 were fired as boosters. The firing results are shown in Figures 1 and 2 of the accompanying drawing in which combustion rate (Vc) is plotted against combustion pressure (P).
Figure 1 was obtained with a propellant in which the isocyanate was HMDI and the nitramine was hexogen, and
Figure 2 with a propellant obtained with the same isocyanate and with octogen as the nitramine.
Claims (16)
1. A process of preparing a composite double base propellant by the in situ casting method, in which at least one polyisocyanate crosslinking agent is introduced together with the casting solvent into the base powder.
2. A process according to claim 1, in which the amount of polyisocyanate crosslinking agent is such that the ratio of NCO to free OH equivalents in the nitrocellulose of the base powder is from 0.015 to 0.2.
3. A process according to claim 2, in which said
NCO/OH ratio is from 0.03 to 0.15.
4. A process according to any of claims 1 to 3, in which the crosslinking agent is a diisocyanate.
5. A process according to any of claims 1 to 4, in which the crosslinking agent is an aliphatic diisocyanate.
6. A process according to any of claims 1 to 5, in which the degree of plasticisation of the propellant obtained is up to 88%.
7. A process according to any of claims 1 to 6, in which the base powder contains up to 5% by weight of a prepolymer having hydroxyl terminations.
8. A process according to claim 7, in which the prepolymer is a polyester or a polyether.
9. A process according to any of claims 1 to 8 in which the base powder contains a solid oxidising charge.
10. A process according to claim 9, in which the oxidising charge is a nitramine.
11. A process according to claim 10, in which the nitramine is hexogen or octogen of a mixture thereof.
12. A process according to claim 10 or 11, in which the base powder contains up to 70% by weight of the nitramine.
13. A process according to any of claims 1 to 12, in which the base powder contains up to 10% by weight of combustion catalysts.
14. A process according to any of claims 1 to 13, in which the base powder contains one or more antiinstability additives.
15. Composite double base propellants when made by the process claimed in any of the preceding claims.
15. A process of preparing a composite double base propellant according to claim 1, substantially as herein described in any of Examples 1 to 6
16. Composite double base propellants when made by the process claimed in any of the preceding claims.
Amendments to the claims have been filed as follows 1. A process of preparing a composite double base propellant by the in situ casting method. in which at least one polyisocyanate crosslinking agent is introduced together with the casting solvent into the base powder, the amount of the crosslinking agent being such that the ratio of NCO to free OH equivalents in the nitrocellulose of the base powder is fro 0.015 to 0 n.s.
2. A process according to claim 1, in which said
NCO/OH ratio is from 0.03 to 0.15.
3. A process according to claim 1 or 2, in which the crosslinking agent is a diisocyanate.
4. A process according to any of claims 1 to 3, in which the crosslinking agent is an aliphatic diisocyanate.
5. A process according to any of claims 1 to 4, in which the degree of plasticisation (as herein defined) of the propellant obtained is up to s8.
6. A process according to any of claims 1 to 5, in which the base powder contains up to 5% by weight of a prepolymer having hydroxyl terminations.
7. A process according to claim 6, in which the prepolymer is a polyester or a polyether.
8. A process according to any of claims 1 to 7 in which the base powder contains a solid oxidising charge.
9. A process according to claim 8, in which the oxidising charge is a nitramine.
10. A process according to claim 9, in which the nitramine is hexogen or octogen or a mixture thereof.
11. A process according to claim 9 or 10, in which the base powder contains up to 70% by weight of the nitramine.
12. A process according to any of claims 1 to 11, in which the base powder contains up to 10% by weight of combustion catalysts.
13. A process according to any of claims 1 to 12, in which the base powder contains one or more antiinstability additives.
14. A process of preparing a composite double base propellant according to claim 1, substantially as herein described in any of Examples 1 to 6.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8310834A FR2680783B1 (en) | 1983-06-30 | 1983-06-30 | PROCESS FOR IMPROVING THE MECHANICAL PROPERTIES OF A DOUBLE COMPOSITE BASED PROPERGOL OBTAINED BY THE MOLDING METHOD AND PROPERGOL THUS OBTAINED. |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8413649D0 GB8413649D0 (en) | 1992-11-18 |
| GB2257968A true GB2257968A (en) | 1993-01-27 |
| GB2257968B GB2257968B (en) | 1993-10-13 |
Family
ID=9290331
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8413649A Expired - Fee Related GB2257968B (en) | 1983-06-30 | 1984-05-29 | Preparation of composite double base propellants |
Country Status (4)
| Country | Link |
|---|---|
| DE (1) | DE3420906C2 (en) |
| FR (1) | FR2680783B1 (en) |
| GB (1) | GB2257968B (en) |
| IT (1) | IT1238359B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8409867D0 (en) * | 1984-04-16 | 1993-06-16 | Ici Plc | Nitrocellulose propellant composition |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1408554A (en) * | 1966-09-01 | 1975-10-01 | Us Navy | Crosslinking of double base propellants |
| GB1427697A (en) * | 1969-08-12 | 1976-03-10 | Hercules Inc | Process for producing cross-linked propellants |
| GB1447025A (en) * | 1966-10-14 | 1976-08-25 | Us Navy | Solution cast double base propellants |
| GB1588605A (en) * | 1978-02-01 | 1981-04-29 | Hercules Inc | Method of preparing slurry-cast propellant |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4029529A (en) * | 1967-07-12 | 1977-06-14 | The United States Of America As Represented By The Secretary Of The Navy | Crosslinked carboxyl containing polymer and nitrocellulose as solid propellant binder |
| US4080411A (en) * | 1968-08-21 | 1978-03-21 | Hercules Incorporated | Slurry-cast propellant method |
| US3798090A (en) * | 1968-12-04 | 1974-03-19 | Hercules Inc | Process for producing cross-linked propellants |
| US4234364A (en) * | 1978-05-30 | 1980-11-18 | Hercules Incorporated | Crosslinked double base propellant binders |
| CA1154260A (en) * | 1979-12-28 | 1983-09-27 | Alliant Techsystems Inc. | Slurry cast double base propellants |
| GB2092563B (en) * | 1981-02-10 | 1984-05-02 | Hercules Inc | Alkoxy substituted aromatic stabilisers for cross-linked cmdb propellants |
-
1983
- 1983-06-30 FR FR8310834A patent/FR2680783B1/en not_active Expired - Fee Related
-
1984
- 1984-05-29 GB GB8413649A patent/GB2257968B/en not_active Expired - Fee Related
- 1984-06-05 DE DE3420906A patent/DE3420906C2/en not_active Expired - Fee Related
- 1984-06-27 IT IT8467650A patent/IT1238359B/en active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1408554A (en) * | 1966-09-01 | 1975-10-01 | Us Navy | Crosslinking of double base propellants |
| GB1447025A (en) * | 1966-10-14 | 1976-08-25 | Us Navy | Solution cast double base propellants |
| GB1427697A (en) * | 1969-08-12 | 1976-03-10 | Hercules Inc | Process for producing cross-linked propellants |
| GB1588605A (en) * | 1978-02-01 | 1981-04-29 | Hercules Inc | Method of preparing slurry-cast propellant |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2257968B (en) | 1993-10-13 |
| DE3420906A1 (en) | 1993-05-19 |
| FR2680783B1 (en) | 1994-05-06 |
| DE3420906C2 (en) | 1996-02-29 |
| IT8467650A0 (en) | 1984-06-27 |
| IT1238359B (en) | 1993-07-13 |
| GB8413649D0 (en) | 1992-11-18 |
| FR2680783A1 (en) | 1993-03-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20000529 |