Title of Invention

"A PROCESS FR PREPARATION OF AN IMPROVED HYDROCARBON BASED FUEL PROPELLANT"

Abstract This invention relates to an improved hydro arbon based furl propel 1 ant. The fuel propellant has an oxidizer, a binder, fuel, an inert plasticizer, a stabilizer, filler, a cross linking agent and a curing, agent. Further this invention relates to an improved process for the preparation of a hydrocarbon based fuel propellant. The process comprises in adding a liquid oxidizer to a polymeric bander, stabilizer and inert plasticizer to obtain a mixture such a mixture is subjected to a stop of desecration. Fillers are added thereto under stirring, a curing agent and then slurring to obtain a slurry. The slurry so obtained is casted in the molded casting such a blurry in moulds.
Full Text This invention relates to a process for preparation of an improved hydrocarbon based fuel propellant.
Fuel rich propellants known in the prior art have an advantage over the rocket propellants that the said propellant uitlises oxygen from outside air for its combustion. The fuel rich propellants known in the prior art are made from hydro-carbon polymers wherein the said hyero-carbon polymers furnciton both as binder and fuel. The oxidizer for such formulations are generally selected from the group of compounds like ammonium perchlorate (AP) or sodium nitrate.
The disadvantage of known such fuel rich propellants are that they have ingintion problem calling for a special igniter for the said purpose which in turn cumbersomes, the whole process and the very prupose of propellant. Mainly powders with AP generally used as binder and fuel is like hydroxy terminated poly-butadiene herein after to be named as HTPB. However, again such formulations suffer from the problems of ignition and sustained combustion. The drawback of such system is that they need flame stabilizer in addition to special igniter again making the system more complex. The known rocket propellant from the prior art generally do not serve the prupose of fuel rich rocket propellant because the latter can use the oxygen from outside air as stated herein above. On the other hand, however in fuel rich rocket propellant with high percentage of nitro glycerine used as oxidizer in rocket propellant has disadvantage because the same will result in lower specific impulse or energy in the secondary chamber, which in turn leads to lesser efficiency of the system to be used for such propellant. The binder and fuel like HTPB is not compatible with nitroglycerine.
Hence, this formulation can not serve as fuel rich propellant.
An object of the present invention is to propose an improved hydrocarbon based fuel-rich propellant containing at least one oxidiser instead of hitherto used solid oxidiser.
Another object of the invention is to propose an improved hydrocarbon based fuel-rich propellant/ HCFRPs wherein the said oxidiser is essentially a liquid oxidiser like nitroglycerine herein after to be named as NG which also acts as plasticiser for the binder within the said formulations.
Another object of the invention is to propose an improved hydrocarbon based fuel-rich propellant for improved ignition process having the lower ignition temperature than the hitherto used oxidisers known in the prior art.
Another object of the present invention is to propose an improved hydrocarbon based fuel-rich propellant having better hcmogenity between solid hydrocarbon based fuel and the said liquid oxidiser which in turn has better combustion characteristics.
Still further object of the present disclosure is to propose a said propellant formulation having suitable elongation properties of about 50 to 150% as compared to known propellant formulations in the prior art.
According to this invention there is provided A process for preparation of an improved hydrocarbon based fuel propellant comprising steps of adding a liquid oxidiser to a polymer binder, a fuel, a stabilizer and inert plasticiser to obtain a mixtue, subjecting the mixture to deaeration, adding fillers with stirring, adding a curing agent at a temperature of 50-70'C with stirring to obtain a slurry, and then casting such a slurry in moulds to obtain a desired propellant, wherein the liquid oxidizer is selected from group of liquid nitrate esters, such as, butane triol trinitrate, triethylene, glycol dinitrate and nitroglycrine and is taken in quantity 15-40% by weight of propellant and wherein ratio of plasticiser to polymer is in the range from 1:1 to 1:4 and wherein the inert plasticizer is selected from non volatile high boiling point organic liquid esters such as di-ethyl phthalate (DEP), di-octyl phthalate (DOP), iso decyl peralgonate (IDP) and wherein stablizer is selected from nitra esters such as carbamite, 2-nitrodiphylamine and diphenylamine and wherein binder and fuel is hydroy terminated block co- polymer in quantity 25 to 80% by weight of propellant and wherein further filler is taken in amount 1-25% by weight of propellant and is selected from polystyrene, nepthalene, fine particulate carbon and metallic powders like aluminium, magnesium, boron and zirconium and further wherein cross linking agent is selected from compounds having hydroxy groups such as trimethylol propane, pyrogalol, resorcinol and nitrocellulose and wherein curing agent is selected from the group of poly functional iso cyanates in amount of 20-25% weight of propellant and wherein catalyst is selected from organo metallic compound such as ferric acetyl acetonate, dibutyl tin dilaurate and triphenyl bismuth.
In accordance with the present invention, the liquid oxidizer is chosen from the group of liquid nitrate esters such as butane triol trinitrate, Tri ethylene glycol dinitrate, NG and preferably NG in the said compostions which in turn has better affinity towards the said polymer binder of the present invention and also acts as plasticiser as described above.
According to another preferred embodiment of the present invention, the inert plasticisers are chosen form the non-volatile, high boiling point organic liquid esters such as Di-ethyl phthalate, herein after to be named as DEP, Di-octyl phtahlate herein after to be named as DOP, Isodecyl peralgonate herein after to be named as IDP and preferably DEP. As stated herein above, the binder for the said formulation disclosed in the present invention according to the more preferred embodiment is HTBCP prepared form HTPB and caprolactone monomer.
Accordingly, the said propellant comprises of stabiliser which are generally taken from
group of nitrate ester stabilizers such as carbamite, 2-nitro diphenylamine or
diphenylamine and preferably carbamite and
fillers like polystyrene, naphthalene or fine particulate carbon, metallic powders like aluminium, magnesium, boron and zirconium and preferably fine particulate carbon and cross linking agents to form three dimensional network in the binder system from the group of compounds having hydroxy groups in the chemical formula like trimethylol propane, pyrogalol, resorcinol or nitrocellulose (NC) having at least nitrogen content 11.6 -12.2% and curing agents which are in turn selected from known such agents from the group of poly functional isocyanates like the one prepared from polyols and diisocyanate having at least 20 to 25% isocyanate in the present said propellant formulations to serve as catalyst, added during curing reactions, is selected from the organo metallic compounds based on metals like ferric acetyl acetonate, dibutyl tin dilaurate, triphenyl bismuth and preferably ferric acetyl acetonate and triphenyl bismuth are used preferably in combination.
In accordance with the process of the present invention, weighed quantity of liquid oxidiser is transferred gently to the other reaction vessel containing weighed quantity of polymer binder, stabiliser and inert plasticiser. The reaction mixture is allowed to homogenise over a period of 12 to 15 hrs, preferably the weight ratio of plasticiser to polymer is of about 1:1 to 1:4 , preferably 1:3.
This reaction mixture is then taken in planetary mixer and deaerated in the elevated temperature of 45-60°C and reduced pressure of preferably 5 to 15 mm of mercury. The additives like fillers are added in selected compositions like 1 to 25%. The stirring is continued for atleast 15-30 minutes under reduced pressure (5 -15 mm of mercury). Curing agent like PP-20 is selected of, about 5 to 10% of total

composition and subsequently stirring is continued for another 10 to 40 minutes preferably 20 to 30 minutes. The resulted propellant slurry is cast in metallic moulds preferably aluiminium moulds and cured in ovens at temperature of 50 to 70°C , preferably 57 to 65°C for about one to several days, to have the desired mechanical properties depending on the requirement of the propellant formulations.
The following examples are illustrated to describe the said propellant formulations and are not intended to limit the scope of the said invention .
The fuel rich propellant compositions according to the preferred embodiments of the present invention are : Example 1:
A solid hydrocarbon based fuel rich propellant prepared according to the described method comprises of hydroxy terminated block copolymer 50 parts, nitroglycerine 40 parts, diethyl phthalate 9 parts, carbamite 1 part, nitrocellulose in dense form 5 parts, carbon black 1 part, curing agent PP-20 -5 parts, ferric acetyl acetonate 0.01 part and triphenyl bismuth 0.01 part. The propellant gave tensile strength 9.5 Kg/cm2, elongation 107%, calorific value 5533 cal/gm, Density 1.11 gm/cc and burn rate 2.0 mm/s in atmospheric conditions.
Example 2:
A solid hydrocarbon based fuel rich propellant prepared according to the described method comprises ot hydroxy terminated block copolymer 60 parts/ nitroglycerine 20 parts, diethyl phthalate 19 parts, carbamite 1 part, nitrocellulose in dense form 5 parts, carbon black 1 part, PP-20 6 parts, ferric acetyl acetonate 0.01 part and triphenyl bismuth
0.01 part. The propellant gave tensile strength
2
6.5 Kg/cm and elongation 97%, calorific value 6381
cal/gm, Density 1.1 gm/cc and burn rate 1.8 mm/s in atmospheric conditions.





I CLAIM:
1 A process for preparation of an improved hydrocarbon based fuel propellant
comprising steps of-
(a) adding a liquid oxidiser to a polymer binder, a fuel, a stabilizer and inert plasticiser to obtain a mixtue, subjecting the mixture to deaeration, adding fillers with stirring, adding a curing agent at a temperature of 50-70'C with stirring to obtain a slurry, and then casting such a slurry in moulds to obtain a desired propellant, wherein the liquid oxidizer is selected from group of liquid nitrate esters, such as, butane triol trinitrate, triethylene, glycol dinitrate and nitroglycrine and is taken in quantity 15-40% by weight of propellant and wherein ratio of plasticiser to polymer is in the range from 1:1 to 1:4 and wherein the inert plasticizer is selected from non volatile high boiling point organic liquid esters such as di-ethyl phthalate (DEP), di-octyl phthalate (DOP), iso decyl peralgonate (IDP) and wherein stablizer is selected from nitrate esters such as carbamite, 2-nitrodiphylamine and diphenylamine and wherein binder and fuel is hydrogerminated block copolymer in quantity 25 to 80% by weight of propellant and wherein further filler is taken in amount 1-25% by weight of propellant and is selected from polystyrene, nepthalene, fine particulate carbon and
metallic powders like aluminium, magnesium, boron and zirconium and further wherein cross linking agent is selected from compounds having hydroxy groups such as trimethylol propane, pyrogalol, resorcinol and nitrocellulose and wherein curing agent is selected from the group of poly functional iso cyanates in amount of 20-25% weight of propellant and wherein catalyst is selected from organo metallic compound such as ferric acetyl acetonate, dibutyl tin dilaurate and triphenyl bismuth.
2. A process as claimed in claim 1 wherein liquid oxidizer is nitroglycerene (NG).
3. A process as claimed in claim 1 wherein inert plasticiser is Di-ethyl phthalate.
4. A process as claimed in claim 1 wherein stabilizer is carbamite.
5. A process as claimed in claim 1 wherein) binder) is hydroxy-terminated block co-polymer prepared from hydroxy terminated polybutadiene and caprolactone monomer.
6. A process as claimed in claim 1 wherein filler is fire particulate carbon.
7. A process as claimed in claim 1 where cross linking agent has at least nitrogen content between 11.6-12.2%.
8. A process as claimed in claim 1 wherein curing agent is prepared from polyols and disocyanates.
9. A process as claimed in claim 1 wherein catalyst is a mixture of ferric acetyl acetonate and triphenyl bismuth, each taken in quantity of 0.01 parts by weight of total composition.
10. A process as claimed in claim 1 wherein curing agent is 5 to 10% by weight of total composition
11. A process as claimed in claim 1 wherein ratio of plasticiser to polymer is 1:3.
12. A process as claimed in claim 1 wherein said deaeration is carried out at 45-60°C under reduced pressure of 5 to 15 mm of mercury.
13. A process as claimed in claim 1 wherein said casting is carried out in aluminium moulds.
14. A process for preparation of am improved hydrocarbon based fuel propellant in claim 1 wherein said curing is carried out at 57-65°C for at least one day.
15. A process for preparation of an improved hydrocarbon based fuel as substantially described and herein illustrated.

Documents:

28-del-1996-abstract.pdf

28-del-1996-claims.pdf

28-del-1996-complete specification (granted).pdf

28-del-1996-correspondence-others.pdf

28-del-1996-correspondence-po.pdf

28-del-1996-description (complete).pdf

28-del-1996-form-1.pdf

28-del-1996-form-2.pdf

28-del-1996-form-3.pdf

28-del-1996-form-4.pdf

28-del-1996-gpa.pdf


Patent Number 193567
Indian Patent Application Number 28/DEL/1996
PG Journal Number 30/2004
Publication Date 24-Jul-2004
Grant Date 30-Jan-2006
Date of Filing 05-Jan-1996
Name of Patentee CHIEF CONTROLLER, RESEARCH & DEVELOPMENT
Applicant Address B-341, SENA BHAWAN, DHQ P.O.NEW DELHI,INDIA
Inventors:
# Inventor's Name Inventor's Address
1 HARIDWAR SINGH NATIONALS OF THE DEFENCE METALLURGICAL RESEARCH LABORATORY, HYDERABAD
2 PRABHAKAR GOPAL SHROTRI NATIONALS OF THE DEFENCE METALLURGICAL RESEARCH LABORATORY, HYDERABAD
3 NIVRUTTI MAHADU WALUNJ NATIONALS OF THE DEFENCE METALLURGICAL RESEARCH LABORATORY, HYDERABAD
4 VENKATRAMAN KRISHNA BHAT NATIONALS OF THE DEFENCE METALLURGICAL RESEARCH LABORATORY, HYDERABAD
PCT International Classification Number C07D 403/02
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA