EP1333015A2 - Semicontiunuous process for making an explosive composite charge having a polyurethane matrix by using two components - Google Patents

Abstract

Semi-continuous production of a composite explosive charge (I) consisting of a solid polyurethane matrix filled with powder (II) containing nitrated organic explosive(s), by charging a mold with a paste obtained by mixing a polyol prepolymer (III), plasticizer (IV), polyisocyanate monomer (V) and (II) then thermally crosslinking. Semi-continuous production of a composite explosive charge (I) consisting of a solid polyurethane matrix filled with powder (II) containing nitrated organic explosive(s), by charging a mold with a paste obtained by mixing a polyol prepolymer (III), plasticizer (IV), polyisocyanate monomer (V) and (II) then thermally crosslinking, includes: (i) discontinuously forming the following homogeneous mixtures by simple mixing: (a) a paste comprising the whole of (II) and (III); and (b) a liquid comprising the whole of (V) ((IV) being distributed between (a) and/or (b) as required); and (ii) continuously mixing (a) and (b) at a weight ratio of 95-99.5 : 5-0.5.

Description

The present invention is in the field military, particularly in the area of explosive ordnance, such as bombs and shells.

More specifically, it aims at a new process for obtaining composite explosive charges solid polyurethane matrix.

We mean, in a classic way, by explosive composite, a pyrotechnic composition functionally detonable, consisting of a matrix solid polymer, in general polyurethane, charged, said filler being pulverulent and containing a filler explosive nitrate organic, for example hexogen, octogen, ONTA (oxynitrotriazole), or mixture of at least two of these compounds.

Composite explosive shipments and how to obtain them are for example described by J. QUINCHON, powders, propellants and explosives, volume 1, Explosives, Technique and Documentation, 1982, pages 190-192. The powdery charge is mixed in a liquid polymerizable resin mixer, for example a hydroxyl-terminated prepolymer. We get a paste that can be poured into a mold and then polymerize by cooking. By the choice and the adjustable resin crosslinking agents, catalysts and other additives, moldings can be obtained from varied characteristics.

This conventional kneading process of all constituents that are introduced and mixed in a mixer in a defined sequence presents disadvantages and limitations.

When the mixture is complete, the dough should be used in a rather short period of time (pot life). The lengthening of pot life by a reduction in the rate of crosslinking catalyst has as a counterpart a increased polymerization time, the temperature being limited, inter alia, by the pyrotechnic nature of certain constituents.

This way of operating therefore requires a compromise technique between pot life and cooking time as well as a mandatory sequence of sequences of kneading and casting of the dough.

It also requires an economic compromise between the size of the mixer and the size of the object mold.

Indeed, if this process "batch" proves enough well suited for making large objects such as underwater mines, torpedoes and bombs he on the other hand, it is very penalizing and expensive to to make a large quantity of small objects molded high speed, for example to make several hundreds of shells of diameter from 50 to 100mm each containing a few hundred grams to a few pounds of composite explosive from a mixed with 1 to 3 t of dough.

It is necessary, in this situation, to have a high pot life to be able to charge many ammunition with the same kneaded, which has as counterpart a duration of crosslinking of the dough particularly long and a very high cost of the cycle due to the downtime of the material and people.

If we reduce the size of the mixer, we reduce the number of ammunition to be filled by kneaded, which is economically penalizing.

The skilled person sought to get out of this straitjacket pot life / cooking time and this sequence mandatory and accurate kneading operations and casting.

J.M. TAUZIA, in a communication entitled "Some comments on Processing Energetic Materials" at Symposium "Compatibility and Processing" organized by the American Defense Prepardness Association (ADPA) October 23-25, 1989 in Virginia Beach (United States) suggests, to solve this problem, a method two-component in which 2 polymeric components chemically stable and approximately same charge rate and the same viscosity are all first made from the constituents, so discontinuous in kneaders.

These 2 pasty components are then mixed with continuously with a mass ratio close to 1.

This two-component process, while allowing many get rid of the pot life / cooking time compromise and makes possible the storage of the 2 components during several weeks, has several disadvantages.

A first drawback is that it turns out to be very delicate to continuously mix the 2 components pasty to obtain a homogeneous product.

A second disadvantage is that the 2 components are pyrotechnically active (presence of explosive) and therefore must all 2 beings made and stored in secure facilities.

A third disadvantage is that the matrix solid polymeric composite explosive eventually obtained is different from what we obtain, with the same constituents in the same proportions, according to the classic "batch" process. Indeed, according to TAUZIA, the isocyanate component is polymeric. The fact of to prepare, intermediately, a prepolymer isocyanate from the starting isocyanate monomer a as a consequence, obtaining a polyurethane matrix solid different from that obtained by the process "Batch" by directly mixing all the monomer isocyanate and all the hydroxyl prepolymer.

This difference in structure of the solid matrix polyurethane causes undesirable differences in mechanical and / or detonation properties, hence the need a very expensive and penalizing requalification of final product.

The two-component process described by J.M. TAUZIA is not so not totally satisfactory.

The main object of the present invention is an improvement of this two-component process and proposes a two-component semi-continuous process for obtaining a explosive composite charge with polyurethane matrix, presenting neither the disadvantages of the "batch" process conventional or the aforementioned disadvantages of the method semi-continuous two-component system described by J.M. TAUZIA.

It was discovered, unexpectedly, that could get a composite explosive charge to polyurethane matrix according to a semi-continuous process two-component, simple and inexpensive, not requiring requalification of the final product, thanks to a very precise combination of technical characteristics relating to the distribution of constituents in the 2 components and the mixing mass ratio of the 2 components.

More specifically, the present invention object a semi-continuous process of obtaining a composite explosive charge consisting of a matrix solid polyurethane loaded with a solid charge, powdery and comprises at least one nitrated explosive organic, by introducing into a mold a pasty explosive composition then crosslinking of this composition, said composition being obtained by mixing constituents comprising essentially a polyol prepolymer, a plasticizer, a polyisocyanate monomer and a solid filler powder comprising at least one nitrated explosive organic.

• on réalise tout d'abord, de façon discontinue, à partir de l'ensemble des constituants, par simple mélange homogène, 2 composants :
  • un composant A pâteux comprenant la totalité du prépolymère polyol et la totalité de la charge pulvérulente,
  • un composant B liquide comprenant la totalité du monomère polyisocyanate,
    le plastifiant étant indifféremment réparti entre les 2 composants A et B,
• on mélange ensuite, de façon continue, le composant A et le composant B de telle sorte que le rapport massique composant A /composant B soit constant et compris entre 95/5 et 99,5/0,5.

This method according to the invention is characterized in that, to obtain the pasty explosive composition:

• first of all, in a discontinuous manner, starting from the set of constituents, by simple homogeneous mixing, 2 components:
  • a pasty component A comprising all of the polyol prepolymer and all of the powdery filler,
  • a liquid component B comprising all the polyisocyanate monomer,
    the plasticizer being indifferently distributed between the 2 components A and B,
• component A and component B are then continuously mixed in such a way that the component A / component B mass ratio is constant and between 95/5 and 99.5 / 0.5.

It should be noted, according to the invention, in addition to mass ratio component A / component B well particular, the fact that components A and B do not have the same viscosity, that one is pasty and includes the total charge and polyol prepolymer, and that the other is liquid and includes all the monomer polyisocyanate, such as, without chemical modification, especially without prepolymerization using a polyol.

This combination of technical characteristics distinctive compared to the two-component semi-continuous process of the state of the art has the effect technique to remove all the aforementioned drawbacks, and to make the process particularly simple and expensive.

Only component A is pyrotechnically active, which considerably limits the constraints of safety, and the mixing of components A and B homogenizes easily.

Moreover, the physicochemical properties, mechanical, detonation and product vulnerability are identical to those of the product obtained according to the classic "batch" process from the same constituents in the same proportions, which avoids a penalizing requalification of the product.

Preparation operations for components A and B are totally independent of mixing operations components A and B and casting and can be performed during masked times. These components A and B can be stored if needed for several weeks before being mixed.

The process according to the invention is moreover totally independent of pot life from the fact that we mix quickly and continuously small amounts of components A and B, which increases the percentage of crosslinking catalyst and decrease accordingly the crosslinking duration of the pasty explosive composition in the mold and / or carry out this crosslinking at a temperature lower.

Cross-linking at room temperature (20 ° C) is even possible, which is particularly advantageous.

According to the present invention, the composition explosive paste is obtained from the constituents used according to the previous methods and which are well known to those skilled in the art.

These constituents essentially comprise a polyol prepolymer, a plasticizer, a monomer polyisocyanate and a powdery filler comprising at least less an organic nitro explosive.

By "essentially", it must be understood that aforementioned constituent are always present and account for more than 90% by weight ratio to the total weight of the explosive composition pasty.

Preferably, the sum of the contents of weight in polyol prepolymer, plasticizer, monomer polyisocyanate and powdery filler represents between 98% and 100% of all constituents.

Generally speaking, physical states, solid, liquid, pasty, constituents and compositions must be understood in this description, as the physical states at the temperature ambient (approximately 20 ° C) and at atmospheric pressure (about 0.1 MPa).

The term "organic nitro explosive" is conventionally understood to mean an explosive selected from the group consisting of aromatic nitro explosives (comprising at least one C-NO _{2 group} , the carbon atom being part of an aromatic ring) , nitric ester explosives (comprising at least one CO-NO _{2 group} ) and nitramine explosives (comprising at least one CN-NO _{2 group} ).

Preferably, the organic nitro explosive is selected from the group consisting of hexogen, octogen, pentrite, 5-oxo 3-nitro 1,2,4-triazole (ONTA), triaminotrinitrobenzene, nitroguanidine and mixtures thereof, that is all mixtures of at least two of the above compounds.

In a particularly preferred manner, the nitrated explosive organic is selected from the group consisting of hexogen, octogen, ONTA and mixtures thereof.

According to a preferred variant, the explosive content organic nitrate is between 15% and 90% by weight compared to the composite explosive and the powdery solid charge is between 75% and 90% by weight relative to the composite explosive.

According to one variant, the powdery solid filler consists only of organic nitro explosive.

According to another variant, the solid charge powder also includes at least one other compound as the organic nitrate explosive.

It can for example include a metal reducing agent, preferably selected from the group consisting of by aluminum, zirconium, magnesium, tungsten, boron and their mixtures. In a way particularly preferred, the reducing metal is aluminum.

The reducing metal content may for example be between 0% and 35% by weight relative to the composite explosive.

The powdery filler may also comprise in combination or not with a reducing metal, a mineral oxidant, preferably selected from the group constituted by ammonium perchlorate, which is particularly preferred, potassium perchlorate, ammonium nitrate, sodium nitrate and their mixtures.

The mineral oxidant content may for example be between 0% and 45% by weight compared to the explosive composite.

When the powdery solid charge comprises at least least one compound other than the organic nitro explosive, this other compound is preferably chosen from group consisting of ammonium perchlorate, aluminum and their mixtures.

According to the present invention, the polyol prepolymer is a more or less viscous liquid. His mass number-average molecular weight (Mn) is preferably between 500 and 10,000 and is preferably chosen in the group consisting of polyisobutylenes polyols, polybutadienes polyols, polyethers polyols, polyesters polyols and polysiloxanes polyols. It is particularly preferred to use a polybutadiene with hydroxyl endings.

The polyisocyanate monomer is a liquid of chosen from the group consisting of the toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), dicyclohexylmethylene diisocyanate (MDCI), hexamethylene diisocyanate (HMDI), trihexane biuret isocyanate (BTHI), 3,5,5-trimethyl-1,6-hexamethylene diisocyanate, and mixtures thereof.

In a particularly preferred manner, IPDI or MDCI.

The plasticizer is also a liquid, preferably a monoester such as pelargonate isodecyl (IDP) or a polyester selected from the group consisting of phthalates, adipates, azelates and acetates. Among the polyesters, triacetin, alkyl phthalates such as dioctyl phthalate (DOP), alkyl azelates such as azelate dioctyl (DOZ) and alkyl adipates as dioctyl adipate (DOA) are particularly preferred.

In addition to the essential constituents mentioned above, all the constituents may also include least one additive selected from the group consisting of crosslinking catalysts (reaction catalysts NCO / OH), wetting agents, antioxidants and binder-filler adhesion agents.

As a crosslinking catalyst, preferably dibutyldilaurate tin (DBTL), but can also use any other well known catalyst of the skilled person, including other compounds organic tin such as a stannous salt of an acid carboxylic acid, a trialkyltin oxide, a dihalide of dialkyltin or a dialkyltin oxide. We can for example, dibutyltin diacetate, diethyltin diacetate, dioctyltin dioxide and the stannous octoate.

It is also possible to use an amine as catalyst tertiary, including trialkylamine, or an organic compound of bismuth, such as Triphenylbismuth.

As the wetting agent, preferably a lecithin such as soy lecithin, or a siloxane.

As an antioxidant, preferably ditertiobutylparacresol (Ionol) or 2,2'-methylene 4-methyl-6-tert-butylphenol (MBP5).

Binder-filler adhesion agent is preferably used triethylene pentamine acrylonitrile (TEPAN), or certain compounds derived from silanols such as triethoxysilyl-3-propyl succinic anhydride (C ₁₃ H ₂₄ O ₆ Si).

Constituents may also include a extender compound polyurethane polymer chain.

This compound is generally a polyol monomer of low mass, less than about 300, preferably one triol such as trimethylolpropane (TMP) or a diol such than dipropylene glycol.

• un composant A pâteux comprenant la totalité du prépolymère polyol et la totalité de la charge solide pulvérulente,
• un composant B liquide comprenant la totalité du monomère polyisocyanate,

le plastifiant étant indifféremment réparti entre les 2 composants A et B. According to the present invention, it is first of all carried out discontinuously, from the set of constituents, by simple homogeneous mixing, 2 components:

• a pasty component A comprising all of the polyol prepolymer and all of the powdery solid filler,
• a liquid component B comprising all the polyisocyanate monomer,

the plasticizer being indifferently distributed between the 2 components A and B.

Preferably, component A comprises the all the plasticizer.

In a particularly preferred manner, component B consists solely of the polyisocyanate monomer.

When the constituents comprise a compound chain expander, this one is imperatively necessary all included in component A.

Where the constituents include at least one additive selected from the group consisting of crosslinking catalysts, wetting agents, antioxidants and binder-filler adhesion agents, this additive can be indifferently distributed between the 2 components A and B, but preferably it is completely included in component A.

According to a preferred variant, the others components that the polyol prepolymer, the plasticizer, the polyisocyanate monomer and the solid charge powder are exclusively selected from the group consisting of the chain extender compounds, the crosslinking catalysts, wetting agents, antioxidants and binder-filler adhesion agents, the chain extensor compounds being in totality included in component A, the catalysts of crosslinking, wetting agents, agents antioxidants and binding-load adhesion agents can they be indifferently distributed between the 2 components A and B. However, they are preferably included in component A.

Components A and B are independently made, discontinuously, by simple homogeneous mixing, by example in a kneader, and are chemically stable, that is, there is no chemical reaction between the mixed constituents of each component, and that all constituents retain their identity structural, both during mixing and during subsequent and independent storage of components A and B.

According to the present invention, to obtain a pasty explosive composition, then mixing, continuously, component A and component B of such that the mass ratio component A / component B is constant and between 95/5 and 99.5 / 0.5, preferably between 98/2 and 99.2 / 0.8, for example neighbor of 99.

This continuous mixing between component A and component B is for example and preferably made in a static mixer, well-known mixer of the person skilled in the art, in the form of a pipe containing braces forcing the product passing through to to separate then to remix.

According to a preferred variant, the components A and B are each contained in a pot equipped with a piston whose the setting in motion, using a motor, allows the supply of components A and B of a convergent located upstream of the static mixer, so that the convergent content pours into the mixer static.

The pressure on the mixture of components A and B in the convergent is preferably between 1MPa and 10MPa and the 2 pistons are preferably moved by the same engine.

Taking into account the mass ratio component A / compound B high, it is interesting to point out that a such equipment offers the possibility of chaining several pots of component A for the same pot of component B, without breaking the continuous process.

The static mixer according to the invention is preferably consisting of several elements mounted in series, shaped like a pipe, having a diameter of preferably between 15mm and 60mm.

For example, between 6 and 15 elements of mixture, such as those sold commercially and well known to those skilled in the art.

According to another preferred variant, the explosive pasty composition with volume flow between 0.1l / min and 5l / min, better understood between 0.3l / min and 1l / min, for example near 0,5l / min.

The aforementioned preferred variant according to which the components A and B are each contained in a pot equipped with a piston allows very precise dosages and a very regular diet, but one can also, by For example, power the static mixer using metering pumps connected to the storage bins of components A and B.

The static mixer is generally provided with a double envelope to allow adjustment of the temperature.

Each element can be regulated at a temperature different. The last element can for example be regulated at the temperature chosen for the crosslinking subsequent explosive paste in the molds, other upstream elements being regulated at a lower temperature.

Pots or bins containing components A and B may also be equipped with a heater.

According to a preferred variant, component A and component B are mixed at a temperature included between 40 ° C and 80 ° C.

According to the present invention, the composition explosive paste obtained after mixing the components A and B is introduced into a mold in which it undergoes then a thermal crosslinking, in a furnace by example.

This crosslinking results from the formation of bridges urethanes because of the reaction of the functions hydroxyls of the polyol prepolymer and optionally chain extender compound with functions isocyanates of the polyisocyanate monomer. The speed of crosslinking increases with temperature and grade as a catalyst.

According to a preferred variant, the mold is constituted by the envelope, generally metallic, of a munition, for example a shell.

In a preferred manner, and especially when using a static mixer to mix continuously components A and B, the pasty explosive composition from the mixer is introduced automatically in a large series of molds, for example several hundreds of shells envelopes.

According to a preferred variant of the invention, the crosslinking temperature of the explosive composition pastry introduced into the molds is included between 15 ° C and 80 ° C.

In particular, it is possible to operate at room temperature (about 20 ° C), which is particularly advantageous.

According to another preferred variant, the temperature crosslinking is identical or similar to that to which component A and component B are mixed.

The following non-limiting example illustrates the invention.

Example 1: Obtaining a composite explosive charge with polyurethane matrix loaded with hexogen Pasty component A

• 7,49 parties en poids du polybutadiène à terminaisons hydroxyles de masse moléculaire moyenne en nombre environ 2500 et de fonctionnalité environ 2,2 en fonctions hydroxyles commercialisé par la Société Atochem sous la dénomination R45HT (prépolymère polyol).
• 0,08 partie en poids de triméthylolpropane (composé extenseur de chaíne).
• 3,37 parties en poids d'adipate de dioctyle (plastifiant)
• 0,12 partie en poids de MBP5 (agent antioxydant)
• 0,12 partie en poids de lécithine de soja (agent mouillant)
• 0,06 partie en poids de TEPAN (agent d'adhésion liant-charge)
• 0,0001 partie en poids de dibutyldilaurate d'étain (catalyseur de réticulation)
• 88,76 parties en poids d'hexogène pulvérulent (charge en explosif nitré organique).

In a stainless steel vertical mixer with a capacity of 35 liters, a homogeneous pasty component A is produced by mixing, at 60 ° C. for 4 hours, the following constituents, in the relative proportions mentioned:

• 7.49 parts by weight of the hydroxyl-terminated polybutadiene of number average molecular weight about 2500 and of functionality about 2.2 in hydroxyl functions marketed by the company Atochem under the name R45HT (polyol prepolymer).
• 0.08 parts by weight of trimethylolpropane (chain extender compound).
• 3.37 parts by weight of dioctyl adipate (plasticizer)
• 0.12 parts by weight of MBP5 (antioxidant)
• 0.12 parts by weight of soy lecithin (wetting agent)
• 0.06 parts by weight of TEPAN (binder-filler adhesion agent)
• 0.0001 parts by weight of tin dibutyldilaurate (crosslinking catalyst)
• 88.76 parts by weight of powdered hexogen (charge in organic nitro explosive).

Liquid component B

Component B is made up of only isophorone diisocyanate (IPDI), that is to say polyisocyanate monomer.

Obtaining a pasty explosive composition, by continuously mixing components A and B

The continuous mixing between component A and component B is made in a static mixer consists of 13 elements mounted in series of length 32mm and diameter 32mm, after transfer of each of components A and B in a pot equipped with a piston. The pot containing component A has a diameter of 300mm and a height of 250mm. The pot containing component B has a 40mm diameter and a height of 250mm.

The setting in motion of the 2 pistons, with the help of a same motor, allows the supply of components A and B a convergent located upstream of the static mixer, so that on the one hand the component mass ratio A / component B is constant and equal to 99.14 / 0.86, and on the other hand that the contents of the convergent pours in the static mixer.

The pressure on the mixture of components A and B in the convergent is 2.5 MPa.

The whole installation, ie including the 2 pots containing components A and B, the convergent and the 13 elements of the static mixer, is thermostated at 60 ° C.

At the output of the static mixer, we obtain the pasty explosive composition with a flow of 0.351 / minute.

• prépolymère polyol : 7,42%
• extenseur de chaíne : 0,07%
• monomère polyisocyanate : 0,86%
• plastifiant : 3,35%
• agent antioxydant : 0,12%
• agent mouillant : 0,12%
• agent d'adhésion liant-charge : 0,06%
• catalyseur de réticulation : 0,0001%
• hexogène : 88,00%

This pasty explosive composition is homogeneous and has the following composition by weight:

• polyol prepolymer: 7.42%
• chain expander: 0.07%
• Polyisocyanate monomer: 0.86%
• plasticizer: 3.35%
• antioxidant agent: 0.12%
• wetting agent: 0.12%
• binder-filler adhesion agent: 0.06%
• crosslinking catalyst: 0.0001%
• hexogen: 88.00%

Obtaining composite explosive charge by casting in a mold and then crosslinking the composition explosive.

The pasty explosive composition coming out of static mixer is poured, at the temperature about 20 ° C in metal molds of square section 80mm x 80mm and height 120mm, previously arranged in a casing connected to a valve located at the outlet of the static mixer, the sealing box-valve being ensured by a rubber.

The dynamic viscosity of the explosive composition pasty at the outlet of the static mixer is 5800 poise.

This mold loading operation is carried out under partial vacuum of about 15mm Hg in the casing.

After loading, the molds are introduced into an oven at 60 ° C. for 7 days, which makes it possible to crosslink the binder of the explosive composition and finally to obtain a composite explosive feed consisting of 12% by weight of polyurethane matrix and of 88% by weight of hexogen, whose density is 1.62 g / cm ³ .

Après 2h : 6900 poises

Après 4h : 7900 poises

Après 6h : 9100 poises.

During crosslinking at 60 ° C. of the composition in the molds, the evolution as a function of time of the dynamic viscosity of this composition was followed:

After 2h: 6900 poises

After 4h: 7900 poises

After 6h: 9100 poises.

Contrainte maximale (Sm) : 0,8 MPa

Module d'élasticité (E) : 15 MPa

Allongement à la contrainte maximale (e_m) : 9%

Contrainte à la rupture (Sr) : 0,8 MPa

Allongement à la rupture (e_r) : 10%

The tensile mechanical properties of the composite explosive obtained were determined using a conventional tensile machine at 20 ° C., with a tensile speed of 50 mm / min, from standard single-sample test pieces, according to a method well known to those skilled in the art (average of 6 measurements):

Maximum stress (Sm): 0.8 MPa

Modulus of elasticity (E): 15 MPa

Elongation at maximum stress (e _m ): 9%

Breaking stress (Sr): 0.8 MPa

Elongation at break (e _r ): 10%

These mechanical properties are satisfactory for this type of loading.

We have also determined, according to the methods and the Julius Peters gear well known to man of the profession, sensitivity to friction and sensitivity to the impact of the resulting composite explosive.

The sensitivity to impact is 25 Joules.

For sensitivity to friction, 20 positive tests on 30 to 353N, maximum limit of the apparatus.

Comparative example

This comparative example is not part of the invention. It was made for the sole purpose of show that the physico-chemical properties and mechanical properties of the composite explosive obtained according to bicomponent semi-continuous process object of the invention are identical to those of the composite explosive obtained from the same constituents, in the same proportions, according to the classic batch process hitherto used by those skilled in the art.

• 7,42 parties en poids du prépolymère polyol utilisé pour l'exemple 1
• 0,07 partie en poids de triméthylolpropane
• 3,35 parties en poids d'adipate de dioctyle
• 0,12 partie en poids de MBP5
• 0,12 partie en poids de lécithine de soja
• 0,06 partie en poids de TEPAN
• 0,0001 partie en poids de dibutyldilaurate d'étain
• 88,00 parties en poids d'hexogène pulvérulent.

According to this comparative example, a vertical mixer of 135 liters is introduced:

• 7.42 parts by weight of the polyol prepolymer used for Example 1
• 0.07 parts by weight of trimethylolpropane
• 3.35 parts by weight of dioctyl adipate
• 0.12 parts by weight of MBP5
• 0.12 parts by weight of soy lecithin
• 0.06 parts by weight of TEPAN
• 0.0001 parts by weight of tin dibutyldilaurate
• 88.00 parts by weight of powdery hexogen.

All these constituents are identical to those used for example 1 (same source and same characteristics).

After mixing for 4 hours at 60.degree. kneader a partial vacuum of about 15mm Hg, then continue stirring again for 4 hours at 60 ° C.

The dynamic viscosity of the dough is then 4800 poise.

Then 0.86 parts by weight of IPDI (even provenance and same characteristics as the one used for example 1), then stirring 30 min at 60 ° C under vacuum partial of 15mm Hg approximately.

The pasty explosive composition obtained has the same weight composition as obtained for the example 1.

This composition is then poured into molds identical to those used for Example 1, then crosslinked at 60 ° C in an oven.

Après 2h : 7300 poises

Après 4h : 9900 poises

Après 6h : 12500 poises

During the crosslinking at 60 ° C. of the composition, the evolution as a function of time of the viscosity was followed, the starting point of the time being the moment of introduction of the IPDI in the kneader:

After 2h: 7300 poises

After 4h: 9900 poises

After 6h: 12500 poises

It can be seen that the evolution of the viscosity of the pasty composition is not significantly different from that measured for Example 1.

The composite explosive obtained after crosslinking 7j at 60 ° C has a density of 1.62 g / cm ³ , the same value as that of the composite explosive obtained in Example 1.

Contrainte maximale (Sm) : 1,0MPa

Module d'élasticité (E) : 18MPa

Allongement à la contrainte maximale (e_m) : 10%

Contrainte à la rupture (Sr) : 1,0MPa

Allongement à la rupture (e_r) : 11%

The mechanical properties of the composite explosive obtained according to this comparative example were determined under the same conditions as those described for Example 1:

Maximum stress (Sm): 1.0 MPa

Modulus of elasticity (E): 18 MPa

Elongation at the maximum stress (e _m ): 10%

Breaking stress (Sr): 1.0MPa

Elongation at break (e _r ): 11%

All these values are not significantly different from those obtained for the composite explosive of Example 1.

We also determined, using the same methods than those used for Example 1, sensitivity to friction and sensitivity to the impact of the explosive obtained composite.

The sensitivity to impact is 21 Joules.

For sensitivity to friction, there are 16 positive tests on 30 to 353N, maximum limit of the apparatus.

These values are not significantly different from those obtained for the composite explosive of Example 1.

Claims (20)

Semi-continuous process for obtaining a composite explosive charge consisting of a filled solid polyurethane matrix whose filler is powdery and comprises at least one organic nitrated explosive, by introduction into a mold of a pasty explosive composition and then thermal crosslinking of said composition, said pasty explosive composition being obtained by mixing constituents essentially comprising a polyol prepolymer, a plasticizer, a polyisocyanate monomer and a pulverulent solid filler comprising at least one nitro-organic explosive, characterized in that , to obtain the pasty explosive composition: first of all, in a discontinuous manner, starting from the set of constituents, by simple homogeneous mixing, 2 components: a pasty component A comprising all of the polyol prepolymer and all of the powdery solid filler, a liquid component B comprising all of the polyisocyanate monomer, the plasticizer being indifferently distributed between the two components A and B, component A and component B are then continuously mixed in such a way that the component A / component B mass ratio is constant and between 95/5 and 99.5 / 0.5. Process according to Claim 1, characterized in that the sum of the weight contents of polyol prepolymer, plasticizer, polyisocyanate monomer and pulverulent solid filler represents between 98% and 100% of all the constituents. Process according to claim 1, characterized in that the constituents also comprise a chain extender compound and in that this compound is wholly included in component A. The process of claim 1, characterized in that the constituents also comprise at least one additive selected from the group consisting of crosslinking catalysts, wetting agents, antioxidants and binder-filler adhesives, which additive is indifferently distributed between the 2 components A and B. Process according to Claim 4, characterized in that the additive is wholly included in component A. Process according to claim 1, characterized in that the other constituents are exclusively selected from the group consisting of chain extender compounds, crosslinking catalysts, wetting agents, antioxidants and binder-filler adhesion agents, chain extender compounds being fully included in component A, the crosslinking catalysts, wetting agents, antioxidants and binder-filler adhesion agents being they indifferently distributed between the 2 components A and B. Process according to claim 1, characterized in that component B consists solely of the polyisocyanate monomer. Process according to Claim 1, characterized in that the mass ratio of component A / component B is between 98/2 and 99.2 / 0.8. Process according to Claim 1, characterized in that the pasty explosive composition is obtained with a volume flow rate of between 0.1 and 51 / min. Process according to Claim 1, characterized in that the mixture between component A and component B is carried out in a static mixer. A method according to claim 10, characterized in that the components A and B are each contained in a pot equipped with a piston whose setting in motion, using a motor, allows the supply of components A and B a convergent located upstream of the static mixer. Process according to Claim 11, characterized in that the pressure on the mixture of components A and B in the convergent is between 1 MPa and 10 MPa. Method according to claim 11, characterized in that the two pistons are moved by the same motor. Process according to Claim 1, characterized in that the static mixer consists of a plurality of mixing elements connected in series. Process according to Claim 1, characterized in that the crosslinking temperature of the pasty explosive composition is between 15 ° C and 80 ° C. Process according to Claim 1, characterized in that component A and component B are mixed at a temperature of between 40 ° C and 80 ° C. Process according to claim 16, characterized in that the crosslinking temperature of the pasty explosive composition is identical or similar to that to which component A and component B are mixed. Process according to Claim 16, characterized in that the crosslinking temperature of the pasty explosive composition is ambient temperature. Process according to Claim 1, characterized in that the polyol prepolymer has a number-average molecular weight (Mn) of between 500 and 10,000 and is chosen from the group consisting of polyisobutylene polyols, polybutadiene polyols, polyether polyols and polyesters. polyols and polysiloxane polyols. Process according to claim 1, characterized in that the polyisocyanate monomer is selected from the group consisting of toluene diisocyanate, isophorone diisocyanate, dicyclohexylmethylene diisocyanate, hexamethylene diisocyanate, biuret trihexane isocyanate, 3,5,5-diisocyanate. trimethyl 1,6-hexamethylene diisocyanate, and mixtures thereof.