Title of Invention

"A PROCESS FOR MANUFACTURE OF FLEXIBLE SHEET EXPLOSIVE BASED ON HYDROXY TREMINATED POLY-BUTADIENE"

Abstract

This invention relates to a process of manufacture of flexible sheet explosive based on hydroxy terminated poly-butadiene, (HTPB). The process comprises in preparing a dioctylphthalate CDOP) coated explosive and subjecting the same to the step of drying. Reacting hydroxy-tersninated poly-butadiene (HTPB) with the DGP in the pressure of a catalyst such as ferric acetyl acetonate in a mixer under vacuum. The coated explosive is added to the reaction mixture, allowing the reaction to proceed under vacuum. Di—isocynate is then added to said reaction mixture upon completion of said reaction and vacuum being released. The reacted mixture being partially cured under relative humidity of 45 to 60% and then roiled to sheets.

Full Text

The present invention relates to the process of manufacture of flexible sheet explosive based on hydroxy terminated poly-butadiene and product thereof, more particularly it relates to the high explosive preferably in sheet form based on hydroxy-terminated poly-butadiene for metal cutting and armoured protection. The high explosives in flexible sheet form are generally manufactured using HMX, PETN or RDX as such distributed in an elastomeric matrix and crepe rubber or poly iso-butylene as binder. The methods of prior art have disadvantages as the poly-iso-butylene is difficult to manufacture and processing of crepe rubber based sheet explosive involves a high temperature rolling operation. Another disadvantage of prior-art is that the manufacturing process is potentially fire hazardous as the solvent used in the process is benzene which catches fire at the processing temperature which in turn is generally higher than its boiling temperature. Yet another disadvantage of the presently known methods of manufacturing such high explosive sheet form and crepe rubber based is that the resulted product has limited shelf life, deteriorates and becomes unstable at extreme ambient conditions on storage. Still another disadvantage of the the methods known in prior art is that , they yield the products with poor mechanical and thermal properties which directly affect the end use of such resulted products. Still further disadvantage of the processes of prior art is that they result in shrinkage in the sheet form high explosive, which in-turn results in non-uniform thickness of the sheet and uncontrolled dimensions of the resulted high explosives in sheet form. Furthermore, because the presently known methods of prior art result in the product with shrinkage, the flexibility is reduced to a greater extent and the resulted product is not flexible enough to be easily adapted for application on any plane, curved or undulated surface. The present invention relates to a useful and improved process of manufacture of flexible sheet explosive based on hydroxy terminated poly butadiene and to the products of the said process with improved properties, and more particularly to a process of manufacture of high explosive based on hydroxy terminated poly butadiene. A object of the present invention is to propose a process of manufacture of flexible sheet explosive based on hydroxy terminated poly-butadiene, here-in-after named as HTPB, and to eliminate the disadvantages of explosives based on crepe rubber and poly-iso-butylene and of processes thereof. Another object of the present invention is to propose a process of manufacture of flexible sheet explosive based on hydroxy terminated poly-butadiene/ and wherein the use of low boiling solvents/ more particular/ hazardous solvents is eliminated, even more particularly the use of such solvents is totally eliminated^ Yet another object of the present is to propose a process of manufacture high explosive based ON HTPB, wherein the resulted product has better and improved mechanical and thermal properties. A still another object of the present invention is to propose a process of manufacture of flexible sheet explosive based on hydroxy terminated ploy-butadiene, and wherein the handling and drying of the high explosive is made more convenient, non hazardous, and safer than the know such processes. It is yet an object of the present invention to propose a process of manufacture of flexible sheet explosive based on the HTPB having homogeneous and uniform thickness with better flexibility, strength, longer shelf life and without any shrinkage which are otherwise resulted due to the use of know reactants i.e. crepe rubber or polyisobutylene, and are overcome in the present invention. According to the present invention, there is provided a process for manufacture of flexible sheet explosive based on hydroxy terminated poly-butadiene (HTPB), comprising the steps of (i) reacting high explosive selected from RDX, HMX, PETN preferably RDX of particle size 5-30 micron, with distilled water in ratio between 1:5 to 1:15 by weight, in an aluminum container, (ii) constantly stirring the reaction mixture and addition of 2 to 7% by weight of dioctylphthalate (DOP), drop by drop to the reaction mixture, (iii) stirring continuously preferably upto 5-10 minutes after addition of DOP, (iv) Alteration of the reaction mixture in a Alteration unit, which preferably comprising a coarse cambric cloth bag to drain out the unreacted water, (v) drying of the reacted mixture by decanting and centrifuging, (vi) air drying of the reacted mixture comprising RDX coated with DOP in drying trays, (vii) reaction of 6-18% by weight of HTPB with 2-12% by weight of DOP in presence of a catalyst such as ferric acetyl acetonate equal to 0.005% by weight of HTPB in a steam jacketed sigma-blade mixture for 15 to 30 minutes, at 40 to 60°C, (viii) addition of the said dried RDX coated with DOP to the reaction and maintaining vacuum preferably equivalent to 10 to 20 mm of mercury for preferably 50 to 70 minutes at 40 to 50°C temperature, (ix) addition of di-isocynate equal to 7 to 12% by weight of HTPB to the reaction mixture, (x) release of vacuum, stirring of the reaction mixture upto 20 to 30 minutes and partial curing of the reaction mixture under controlled humidity preferably 45 to 60%, (xi) rolling of the cured reaction mixture into flexible explosive sheets by passing between two rollers of vertical rolling machine, 90 minutes after completion of the said reactions, wherein the gap between the said roller is kept 12 to 18 mm initially which is subsequently reduced to the desired thickness of the flexible explosive sheet, (xii) cutting the flexible explosive sheets into sheets of desired size using brass knife and drying under controlled humidity to obtain the flexible sheet explosive based on HTPB. Other objects and further applicability of the present invention will become more apparent when taken in conjunction with accompanied description and working examples. According to the present invention the process for manufacture of flexible sheet explosive based on HTPB is proposed comprising of reaction of high explosives such as RDX, HMX, PETN preferably RDX of particle size 5-30 micron, more particularly 5-15 micron with distilled water in ratio of 5 to 13 times by weight more preferably in ratio of 1:0 to 10.0 by weight, in an aluminium container, under constant stirring and uniform suspension is maintained by stirring. To this reaction mixture, DOP is added dropwise preferably from the connected separating funnel and stirring is continued preferably upto 5-10 min after addition of 2-7% by weight of DOP more preferably 3-6% by weight of DOP. The reacted mixture is poured into Alteration unit, which is preferably a coarse cambric cloth bag to drain out the unreacted water. The last traces of unreacted water are 'decanted off after centrifuging the reacted mixture contained in the said bag. On complete removal of unreacted water, the reacted mixture RDX coated with DOP is transferred to drying trays and is air dried avoiding the risk of hazardous treatment due to room temperature treatment. The second step according to the disclosed process of the present invention comprises of reaction of 6-18% by weight preferably 7-13% by weight of HTPB with 2-12% by weight, preferably 4-9% by weight of DOP in the presence of 0.005% by weight of HTPB of ferric acetyl acetonate which in turn acts as catalyst and enhances the reaction rate and results in higher yields on curing, in a steam jacketed sigma-blade mixer for 15 to 30 min, more preferably for 15 to 20 min at 40 to 60 deg C more preferably at 45 to 50 deg C, thus avoiding wastage of time and high temperature treatment. To this reacted mixture, RDX coated with DOP is added and vacuum preferably of 10mm to 20mm Hg is applied for preferably 50 to 70 min at 40 to 50 deg C temperature. Once the second step reaction is complete the di-isocynate in 7 to 12% by weight of HTPB is added to same reaction vessel and vacuum is released, stirring is continued for 20-30 min, preferably upto 20 min. The reacted mixture is kept for partial curing under controlled relative humidity preferably 4 5 to 60 % and then rolled to result in sheet form between two rollers of a vertical rolling machine after of about 90 min of completion of the said reaction. The rolling is performed initially by maintaining gap between the two rollers at 12-18 mm preferably 12 to 14 mm and subsequently gap is narrowed down to the desired thickness of the sheet and which in turn results in uniform thickness and avoided shrinkage, which is also avoided due to controlled partial curing at controlled relative humidity. The yielded sheet form explosive can be cut into the desired size using preferably a brass knife and a temperature. The explosive is allowed to dry under controlled humidity preferably after rolling into sheet form and cutting into desired size. The invention is illustrated in the reaction scheme as of the accompanying drawing shown in fig l./and by the following examples which are not intended to limit the scope of the invention. Example : 1 :- 60gm of hydroxy terminated poly butadiene (hereinafter known as HTPB), 40 gm of dioctyl phthalate (hereinafter known as DOP ) and 0.01 gm ferric acetyl acetonate (hereinafter known as FAA) and licithyne ( 3 gm) are transferred into a steam jacketed sigma mixer and the mixer is stirred for 20 minutes under vacuum and at ambient temperature and controlled related humidity (50%) to the reaction. Fairly 850 gm of cyclotrimethylene trinitramine (hereinafter known as RDX) ( 5-15 micron size) coated with 50 g of DOP is added in two instalments to achieve completion of reaction. Each time stirring is continued for 5 minutes under normal pressure, subsequently under vacuum at 50 deg C for one hour. Accordingly the stirring is stopped and the reacted mass is cooled to 40 deg C by cooled water in the steam jacked mixer. 5.5 g of curing agent Diphenylmethane di- isocynate (hereinafter known as DDI) is added and stirring is continued without vacuum for 30 minutes. The reacted mass is transferred to stainless steel tray and allowed to attain semi curing condition. Subsequently rolling is carried out between 2 horizontal rollers and rolled at ambient temperatures. The HTPB based explosive is obtained in the flexible form and subsequently cut to desired shape and size with the help of template and allowed to cure at ambient condition. The mechanical properties of the product are - Percentage elongation = 13.33 Ultimate Tensile strengths 2.04 kg/cm2 Example 2 96 gms of HTPB, 64 g of DOA and 0.01 gm of FAA and 3 g of Licithyne are transferred to a steam jacketed sigma blade mixer and processed as in Example 1 with 800 g of fine RDX coated with 40 g of DOP and 8.8 gms of DDI. The mechanical properties of dumbell shaped samples of HTPB based explosive under - Percentage elongation = 9.33 Ultimate Tensile strength= 3.14 kg/cm2 WE CLAIM 1. A process for manufacture of flexible sheet explosive based on hydroxy terminated poly-butadiene (HTPB), comprising the steps of i) reacting high explosive selected from RDX, HMX, PETN preferably RDX of particle size 5-30 micron, with distilled water in ratio between 1:5 to 1:15 by weight, in an aluminum container, ii) constantly stirring the reaction mixture and addition of 2 to 7% by weight of dioctylphthalate (DOP), drop by drop to the reaction mixture, iii) stirring continuously preferably upto 5-10 minutes after addition of DOP, iv) Alteration of the reaction mixture in a Alteration unit, which preferably comprising a coarse cambric cloth bag to drain out the unreacted water, v) drying of the reacted mixture by decanting and centrifuging, vi) air drying of the reacted mixture comprising RDX coated with DOP in drying trays, vii) reaction of 6-18% by weight of HTPB with 2-12% by weight of DOP in presence of a catalyst such as ferric acetyl acetonate equal to 0.005% by weight of HTPB in a steam jacketed sigma-blade mixture for 15 to 30 minutes, at 40 to 60°C, viii) addition of the said dried RDX coated with DOP to the reaction and maintaining vacuum preferably equivalent to 10 to 20 mm of mercury for preferably 50 to 70 minutes at 40 to 50°C temperature, ix addition of di-isocynate equal to 7 to 12% by weight of HTPB to the reaction mixture, x. release of vacuum, stirring of the reaction mixture upto 20 to 30 minutes and partial curing of the reaction mixture under controlled humidity preferably 45 to 60%, xi rolling of the cured reaction mixture into flexible explosive sheets by passing between two rollers of vertical rolling machine, 90 minutes after completion of the said reactions, wherein the gap between the said roller is kept 12 to 18 mm initially which is subsequently reduced to the desired thickness of the flexible explosive sheet. xii cutting the flexible explosive sheets into sheets of desired size using brass knife and drying under controlled humidity to obtain the flexible sheet explosive based on HTPB. 2. The process as claimed in claim 1, wherein the preferable ratio of the high explosive selected from RDX, HMX, PETN to the distilled water is 1:10. 3. The process as claimed in claim 1, wherein the preferable particle size of RDX is 5-15 micron. 4. The process as claimed in claim 1, wherein the preferable percentage of DOP added to the reaction mixture is 3 to 6%. 5. The process as claimed in claim 1, wherein reaction of preferably 7-13% by weight of HTPB with preferably 4-9% by weight of DOP is carried out in presence of ferric acetyl acetonate as catalyst equal to 0.005% by weight of HTPB, preferably for 15 to 20 minutes, preferably at a temperature of 40 to 60°C. 6. The process as claimed in claim 1, wherein stirring of the reaction mixture is continued preferably upto 20 minutes after addition of di-isocynate to the reaction mixture and release of vaccum. 7. The process as claimed in claim 1, wherein the gap between the said two roller is initially kept preferably between 12 to 14 mm and subsequently narrowed down to the desired thickness of the said flexible sheet explosive. 8. A process for manufacture of flexible sheet explosive based on hydroxy terminated poly-butadiene (HTPB) substantially as herein described and illustrated.

Documents:

2401-del-1995-abstract.pdf

2401-del-1995-claims.pdf

2401-del-1995-complete specification (granted).pdf

2401-del-1995-correspondence-others.pdf

2401-del-1995-correspondence-po.pdf

2401-del-1995-description (complete).pdf

2401-del-1995-drawings.pdf

2401-del-1995-form-1.pdf

2401-del-1995-form-2.pdf

2401-del-1995-form-4.pdf

2401-del-1995-form-9.pdf

2401-del-1995-gpa.pdf