REACTIVE PLASTICIZER BASED ETHER FOR EXPLOSIVES WITH A PLASTIC BINDER

The present invention relates to a reactive plasticizer energy consumption of a plastic-bonded explosive, and specifically a reactive plasticizer energy consumption of a plastic-bonded explosive which has performance and a high insensitivity, without problem of migration of a plasticizer by being bonded to a polymer binder for a plastic-bonded explosive.

Currently, efforts to provide insensitive energetic materials are an issue important in the development of explosives and a propellant. In such efforts, plastic-bonded explosives (PBX) having a low sensitivity and improved mechanical properties while maintaining high energetic properties have been developed. Today these PBX elemental component become a high energy explosives, polymeric binders and other additives used in a small amount such as a plasticizer or stabilizer.

Currently, a polyurethane polymer binder based on hydroxyl terminated polybutadiene (HTPB) is used as the polymeric binder system which broadly applicable, together with various additives to improve processability, mechanical properties and chemical stability. Although such a binder polymer is excellent for making materials insensitive high energy, it has been suggested that it may disadvantageously generally reduces the energy density of a PBX as a whole because of its low energy potential. In this regard, many studies have been made to increase the total energy density developing energetic binders and plasticizers containing energetic functional groups such as, for example, nitro (C-NO2), nitrate (o- ΝΟ 2), nitramine (N-NO2), azido (-N₃ ) and difluoroamino (-NF2) and application thereof.

The term "energetic functional groups", in this context, has a common and general meaning as used in the field of molecular explosives, i.e. referring to functional groups, when being applied to an explosive or molecular plasticizer, known to contribute to the increase of the total power level of the explosive or plasticizer PBX are applied. Nitro (C-NO2), (O-NO2) nitrate, nitramine (N-NO2), azido (-N₃ ), difluoroamino (-NF2) or the like as above may be mentioned. The term "energy", in the present context, means that the total power level of a molecular explosive is more increased by any known methods comprising introducing such functional groups "energetic".

However, the polymeric binders and plasticizers comprising such energetic functional groups have problems such as poor temperature stability, incompatibility with explosives and low processability. Therefore, it was important to obtain a developing problem finally both performance and a high insensitivity in explosives. Furthermore, when an energetic plasticizer is applied, a problem such as migration of the additional energetic plasticizer from the PBX occurs over a long period of time. Such migration of plasticizer involves additional problems in PBX of increased sensitivity to shock and a decrease in the storage stability due to deterioration of mechanical properties. Therefore, the production of an explosive having both performance and a high insensitivity is still an important objective to be achieved in the art.

When a highly energetic polymer, which can achieve both performance and a high insensitivity is prepared, it is intended to obtain a new energetic material which is combined with an explosive and a binder and has excellent performance and security.

The present invention provides an energy reactive plasticizer which can meet the performance and high explosives required insensitivity in the next generation, the migration of the plasticizer, and prevent various problems accompanying such migration.

A PBX is mainly composed of a molecular explosive, and a prepolymer and a curing agent for forming a binder, and further comprises other additives such as a plasticizer as required. All components are introduced, mixed together and then charged in a container for an explosive, this procedure being called casting process. The prepolymer and the curing agent react in the container to form a binder while solidifying the components in the container.

The "reactive plasticizer" alkyne compound is a high energy, having a low viscosity, which can be used as a plasticizer during mixing the PBX and be bonded to a polymer in a molding process or curing as described above. The reactive plasticizer acts as a plasticizer in the preparation the PBX, and a part or whole of the plasticizer is bound in a binder by click reaction by itself in a curing process, the process of final preparation.

The present inventors have found that by using a reactive plasticizer to introduce prepolymers high energy in a process of preparing a PBX, functioning as a plasticizer during the casting process, thereby solving the conventional problem of viscosity and, further, it binds to a binder during a curing process, thereby reducing the exudation or migration of a plasticizer, and have realized the present invention.

In other words, the present invention provides a novel reactive plasticizer having a high energy potential comprising a functional group high energy as well as a functional group which can react with a prepolymer power/hardener therefor during a curing process for the preparation of a binder for PBX, so as to be bonded to the polymer binder high energy as a side chain thereof.

The reactive plasticizer energy of the present invention binds to a side chain of a binder via a click reaction between acetylene azide groups and during the curing process. For such a reaction, the reactive plasticizer energy of the present invention comprises functional groups acetylene and the connection between the energy functional group and the reactive functional group is an ether bond. In this regard, the new energy reactive plasticizer according to the present invention may be classified as a reactive plasticizer ether having a high energy potential, because the link type shaped feature in the skeleton of the compound is an ether bond.

The reactive plasticizer-based energetic ether is a compound based on an ether obtained according to the following reaction scheme 1:

[Reaction Scheme 1]

(wherein, n = integer selected from 1 to 10).

As can be observed in the reaction scheme 1 above, the energetic plasticizer reagent containing ether groups in the backbone chain is formed by the acetal-forming reaction between 2, 2-dinitropropanol (DNP-OH) and an alcohol containing an acetylene (AA).

The acetal-forming reaction is conducted by the reaction of an aldehyde and an excess amount of an alcohol, under the reaction conditions conventionally known in this field of the art, so that an energy reactive plasticizer comprises ether groups in the backbone chain is synthesized by the competitive reaction between dnp-OH and an alcohol containing an acetylene.

The alcohol containing an acetylene used in the reaction above comprises, for example, propargyl alcohol (n = 1) and 3-butyn-ol (n = 2), to obtain 3-( (2, 2- dinitropropoxy) methoxy) Propyne (DNPMPY) or 4-( (2, 2- dinitropropoxy) méthox)-but-yne) (DNPMBY), respectively.

~ i

Fig. 1 is a drawing representing the result of the infrared spectroscopy ft- DNPMPY.

Fig. 2 is a plot representing the result of the DNPMPY ACD.

Fig. 3 is a plot representing the result of the infrared spectroscopy ft- DNPMBY.

Fig. 4 is a plot representing the change in viscosity of a prepolymer polyol APU, the DNPMPY prepared and a mixture thereof (1:1 by weight) as a function of temperature, respectively, as measured in the test example 1.

Preparation Example 1:

Synthesis and analysis of 3-( (2, 2- dinitropropoxy) methoxy) Propyne (DNPMPY)

Energy a reactive plasticizer, DNPMPY is synthesized by a reaction of forming an acetal as shown by the following reaction scheme 2.

[Reaction scheme 2]

30 mL of dichloromethane (MC), DNP-OH (5 g, mmol 33.56) and propargyl alcohol (Pa) (5.64 g, 100, 68 mmol) are placed in a vial under nitrogen atmosphere necks 2, and 1, 3, 5-trioxane (2.21 g, 24.61 mmol, or para-formaldehyde) is then placed under stirring. The mixture is stirred at 0 °C for 10 minutes and then the bf₃ . Oet2 (10.48 g, 73.83 mmol) is slowly added dropwise. The reaction temperature is brought to room temperature and held for more than react for 3 hours. The reagent is poured into 50 ml of distilled water, washed with a solution of NaHC0₃ (10%)and then washed additionally two or more times with distilled water. After removing the solvent under reduced pressure, it is then purified by chromatography (eluted with ethyl acetate: hexane = 1:5), thus leading to the DNPMPY.

The conformation of the obtained DNPMPY is identified by the following methods. Firstly, the NMR¹ H and¹³ C are used to identify the molecular structure, with the following results: NMR¹ H (CDC1₃ , d, PPM):

2,20 (-CH₃ ), 2.45 (=C-H), 4.20 (-CH₂ -), 4.30 (-CH₂ -), 4.75 (-CH₂ -). NMR¹³ C (CDC1₃ , d, PPM): 20, 0, 55, 5, 69, 0, 79, 0, 94.5, 117.5.

Elemental Analysis (%) Regarding

synthesized is conducted, and the results

follows: calculated for DNPMPY (%): C 38.53,

12,84, 44.01 O, measured: C 38.95, 4.25 hours,

43,16.

h the DNPMPY are as 4.62, N N 13.64, O

As shown in fig. 1, the synthesis of DNPMPY is identified from absorption peaks of functional groups in the spectrum results ft-Ri, and the results are as follows: ri (CNT¹ ) 3300 (=C-H), 2930 (aliphatic, -C-H), 2300 (-C=C), 1590 (-NO2) •

The thermal characteristics of the energetic reactive plasticizer prepared, DNPMPY , are measured by differential scanning calorimetry (ACD) and the results are presented in fig. 2. ACD according to the results, the glass transition temperature (T_g ) of the reactive plasticizer prepared energy, DNPMPY , is -89 °C, which is lower than about 35 °C Tg platiciser glycidyl azide polymer (GAP) (-55 °C).

Synthesis and analysis of 4-( (2, 2- dinitropropoxy) methoxy)-but-yne) (DNPMBY)

Energy a reactive plasticizer, DNPMBY , is synthesized by a reaction of forming an acetal as described in the following reaction scheme 3.

[Reaction Scheme 3]

30 mL of dichloromethane (MC), DNP-OH (4 g, 26.85 mm) and 3-butyn-1-ol (bo), (5,52g, 80.55 mmol) are placed in a vial under nitrogen atmosphere necks 2, and 1, 3, 5-trioxane (1.61 g, 17,9 mmol, or para-formaldehyde) is then placed under stirring.

The mixture is stirred at 0 °C for 10 minutes and then the bf₃ . Oet2 (11.44 g, 80.55 mmol) is slowly added dropwise. After stirring at 0 °C during 40 minutes, the reaction temperature is brought to room temperature and held for more than react for 5 hours. The reagent is poured into 50 ml of distilled water, washed with a solution of NaHC0₃ (10%)and then further additional washed two or more times with distilled water. After removing the solvent under reduced pressure, it is then purified by chromatography (eluted with ethyl acetate: hexane = 1:7 V: V), thereby leading to the DNPMBY.

The conformation of the obtained DNPMBY is identified by the following methods. Firstly, the NMR¹ H and¹³ C are used to identify the molecular structure, with the following results: NMR¹ H (CDC1₃ , d, PPM):

2.09 (=C-H),2, 15 (-CH₃ ), 2.44 (-CH₂ -), 3.61 (-CH₂ -0-), 4.35 (-0-CH2-0-), 4.68 (-CH₂ -0-). NMR¹³ C (CDC1₃ , d, PPM): 20.0, 20.1, 67.1, 69.0, 70.2, 82.1, 96.5, 117.5.

Elemental Analysis (%) for the synthesized DNPMPY is carried out, and the results are as follows: calculated for DNPMBY (%): C 41.38, 5.21 H, N 12.06, 41.35 O, measured: C 41.60, 5.34 H, N 12.97, 40.09 O.

As shown in fig. 3, the synthesis of DNPMBY is identified from absorption peaks of functional groups in the spectrum results ft-Ri, and the results are as follows: ri (CNT¹ ) 3300 (=C-H), 2930 (aliphatic, -C-H), 2300 (-C=C), 1590 (-N0₂ ).

Plasticizing properties of the plasticizer prepared, used for the preparation of PBX, are determined by measuring the decrease in the viscosity of a mixture of said plasticizer and a prepolymer as well as decreasing the glass transition temperature, and the results are described in the following test example.

Decreasing the viscosity of a prepolymer due to the plasticizer

To measure the viscosity, a viscometer, MCR 301 of Anton Paar physica Co ., is used by using a parallel plate has a spacing of 1 mm (CP25 -1- SN9356 , diameter = 2.5 mm), in the temperature range of 30 to 60 °C, to a constant shear rate of 1.0 S^-1 and with a rate of temperature rise of 1 °C/minute. After measuring the viscosity of the prepolymer polyol APU as such, the viscosity of a mixture of said plasticizer DNPMPY obtained by the aforesaid Preparation Example 1 and the gap polyol prepolymer (1:1 m/m) is measured, to determine the plasticizer properties represented by the lowering of the viscosity. The test results obtained in the case where a plasticizer obtained according to Preparation Example 1, i.e. DNPMPY , is applied are represented in fig. 4. As shown in fig. 4, compared to the viscosity of a prepolymer polyol gap, the viscosity of a mixture of said plasticizer prepared according to the present invention and a gap polyol prepolymer is significantly lower, within the total range of the measuring temperatures, demonstrating the plasticizing effect significant DNPMPY synthesized plasticizer of the present invention.

The plasticizing effect represented by the lowering of the viscosity of an energetic plasticizer conventionally been used as BDNPF/BDNPA;

BDNPF/ BDNPDF ; BDNPF/ BDNBF is also shown in the following Table 1 for comparison. The viscosity was measured under the same test conditions as those described in connection with the measurement of viscosity of the plasticizer prepared according to the present invention. As reference, the viscosity of the prepolymer gap polyol itself is and 6,015 cp at 30 °C 1,035.5 to 60 °C, respectively.

BDNPF: bis (2, 2-dinitropropyl) formed

BDNPA: bis (2, 2-dinitropropyl) acetal

BDNPDF: bis (2, 2-dinitropropyl) diformai

BDNBF: bis (2, 2- dinitrobutyl) formed

As shown by Table 1, it can be confirmed that the plasticizer DNPMPY prepared according to the present invention has an excellent effect of lowering the viscosity of the polyol prepolymer gap.

The reactive plasticizer energy of the present invention is configured to be present in a form bound to the binder polymer by a covalent bond with the branch of the polymer backbone of the polymeric binder during a curing process, to prevent a problem of conventional migration or an energetic plasticizer exudation from the PBX molded plastic, while providing the essential physical properties required of an energetic plasticizer PBX used in the preparation of plastics, such as improved energy density processability improved by a reduced viscosity in a mixing process.

When the energetic reactive plasticizer according to the present invention is applied to the preparation of plastic PBX, the conventional problem of migration of the plasticizer from the PBX plastics can be avoided, leading to additional advantageous effects such as an improvement in the property of long term preservation of PBX and an increase in the energy density in the total composition.