WO2016079453A1

WO2016079453A1 - Thin composite explosive products and preparation thereof

Info

Publication number: WO2016079453A1
Application number: PCT/FR2015/053158
Authority: WO
Inventors: Philippe Ragon; Karol WOIRIN
Original assignee: Herakles
Priority date: 2014-11-21
Filing date: 2015-11-20
Publication date: 2016-05-26
Also published as: FR3028852B1; FR3028852A1; CA2968255A1; IL252369A0; EP3221283A1; EP3221283B1; IL252369B; US20180346393A1

Abstract

The present invention relates to composite explosive products and the preparation thereof. Said products have: - a composition, expressed in weight percentages, which contains: from more than 85 to 92%, advantageously from 88 to 90%, of organic energetic charges; said organic energetic charges a) being selected from octogen (HMX), hexogen (RDX), hexanitrohexaazaisowurtzitane (CL20) and penthrite (PETN) charges and mixtures thereof and b) having a particle size distribution with a D₉₀ value of less than 15 µm and a D₅₀ value of less than or equal to 5 pm; and from more than 7 to 12%, advantageously from 8 to 10%, of a polymeric rubber selected from polyurethane-polyester rubbers, polyurethane-polyether rubbers and mixtures thereof, the number-average molecular weight of which is greater than 20 000 g/mol and the Mooney viscosity of which is between 20 and 70 ML (5 + 4) at 100°C; and - a thickness of from 0.4 to 5 mm, advantageously from 1 to 2 mm. Said products may in particular consist of miniaturized systems for multipoint initiation of explosive charges.

Description

LOW THICK COMPOSITE EXPLOSIVE PRODUCTS AND THEIR PREPARATION

The present invention relates to composite explosive products of small thickness (small thickness perfectly controlled), conformable (i.e. deformable, by action of temperature, with shape retention) and efficient. They contain a high rate of energy charges in a binder of a specific nature. They consist in particular of sheets or products obtained by cutting such sheets, such as miniaturized multi-point initiation networks of explosive charges, for example explosive military heads.

The present invention also relates to a process for preparing said composite explosive products. Said process is particularly easy to implement: at temperatures perfectly compatible with the sensitivity of the energy charges present, without the use of a solvent and including only one type of operation.

For explosives in the shape of a sheet or bar (usually of circular, square or rectangular section), there is a dimension value, respectively of thickness or of section, below which the detonation initiated at a point undergoes a weakening then stops after a certain route, leaving part of the explosive intact. This minimum dimension (thickness or section), below which there is no propagation of the stable detonation, is called the critical thickness or section of detonation. We also speak of critical diameter of detonation for a cylindrical bar.

This critical detonation dimension is determined from degressive-sized samples (stepped cylindrical rods, degressive section, for example), the detonation being initiated on the side of the sample with the largest dimension (on the bar side presenting the largest section). For some applications, it seeks high performance explosives thin. However, it is obviously imperative that this small thickness remains greater than their critical dimension of detonation. Explosives with critical dimensions of detonation as low as possible are therefore sought. Such a small critical dimension of detonation is suitably less than or equal to 5 mm, even less than or equal to 1.5 mm, or even less than or equal to 1 mm. Thus, in the context of miniaturized networks for multipoint ignition of explosive charges (such a network has for example the geometry shown in FIG. 5 of the patent application WO 2010/066752), explosives with a critical dimension of detonation are also sought. as small as possible to constitute the channels of said networks (having a section as small as possible but capable of ensuring the propagation of the detonation, including in the angles).

According to the prior art, we have already been interested in performing thin explosives and obtaining them.

US Pat. No. 3,354,010 discloses explosive products, in the form of flexible sheets (typically of a thickness of 6.3 mm), the composition of which contains organic energy charges of hexogen (HMX) and / or octogenous (RDX) type. ), in a binder (nitrocellulose) plasticized (tributyl acetyl citrate). These products are a priori obtained according to two methods, both of a relatively complex implementation: 1) obtaining a mixture comprising a solvent, evaporation of said solvent, obtaining granules and then shaping by extrusion, molding or rolling, or 2) obtaining, by hot kneading, a paste comprising ethanol and rolling said paste.

Elastomers (gums, "raw" (non-crosslinked) rubbers) of the polyurethane-polyester type (ie of polyurethane type with flexible segments of polyester type) and / or polyurethane-polyether (ie of polyurethane type with flexible segments of polyether type), are by elsewhere marketed, in recent years, particularly under the trademark UREPAN ^® by RheinChemie and under the Millathane ^® brand by TSE Industries. The present invention provides an original outlet for this type of elastomer.

In such a context, the person skilled in the art is always looking for an explosive product of small thickness (perfectly controlled), conformable, efficient (ie critical dimension of weak detonation (in reference to its small thickness (see below). above)) and easy to manufacture.

It is the merit of the inventors to propose such a product consisting essentially of specific energy charges (said "high" energy ("sensitive") charges being present, under a fine granulometry (micron), at a "maximum" rate (> 85 % by weight)) and a binder of a new type, said binder making it possible to obtain said product by a process that is particularly easy to implement (does not require the use of a solvent, does not require a high temperature (dangerous in view of the sensitivity of the charges) with reference to the viscosity of the binder, requiring only a single type of operation, in a single type of device (mixer (s) with cylinders), or even in a single device (roller mixer) (see below). It was not obvious to obtain explosive products heavily loaded fine particle size, much less obvious to obtain such products by a process of easy implementation.

According to its first object, the present invention therefore relates to new composite explosive products. Said products, having a small critical dimension of detonation in view of their specific composition (composition containing a high level of charges, charges "highly" energy ("sensitive") and fine particle size), therefore associate, with said specific composition, a thin (but obviously greater than or equal to their small critical dimension detonation). Typically, the composite explosive products of the invention exhibit:

a composition, expressed in percentages by weight, which contains:

+ from 85 to 92%, advantageously from 88 to 90%, of organic energy charges; said organic energy charges a) being selected from octogen (HMX), hexogen (RDX), hexanitrohexaazaisowurtzitane (CL20), pentrite (PETN) and mixtures thereof and b) having a particle size distribution with a value of of D ₉₀ less than 15 μm and a value of D ₅₀ less than or equal to 5 μm; and

+ from 7 to 12%, advantageously from 8 to 10%, of a polymeric gum chosen from polyurethane-polyester gums, polyurethane-polyether gums and mixtures thereof, the number-average molecular mass of which is greater than 20,000 g / mol and whose Mooney viscosity is between 20 and 70 ML (5 + 4) at 100 ° C; and

a thickness of 0.4 to 5 mm, advantageously 1 to 2 mm.

It can already be noted that the ranges indicated for the contents of charges and binding are narrow ranges. It is with such contents (of the specified nature and the (fine) granulometry specified) and binder (of the specified nature) that the desired results were obtained. The mechanical properties of the "obtained" products (assuming that said products can be obtained) with more charges are unsatisfactory; the energetic performances (and in particular the critical dimensions of detonation) of the products obtained with less loads are not satisfactory (one recalls that one targets critical dimensions of detonation lower or equal to 5 mm, even lower or equal to 1, 5 mm, or even less than or equal to 1 mm).

As indicated above, the composite explosive products of the invention thus contain a high level of "Strongly" energetic ("sensitive") organic and fine granulometry in a binder of a new type.

The composite explosive products of the invention contain from 85 to 92%, advantageously from 88 to 90% (% by weight), of specific organic energy charges.

The charges in question are "highly" energetic ("sensitive") charges. These are octogen (H MX) charges, hexogen (RDX) charges, hexaazaisowurtzitane (CL20) charges, pentrite charges (ΡΕΓΝ) or a mixture of such charges. Advantageously, these are charges of hexogen (RDX), charges of hexanitrohexaazaisowurtzitane (CL20) or a mixture of these two types of charges (the most energetic).

The charges in question are not present in the form of large and small crystals, they are present only in the form of small crystals. These are (fine) fillers which have a particle size distribution with a value of D _{90 of} less than 15 μητι and a value of D ₅₀ less than or equal to 5 μιη (the notion of "fine" fillers, "small" crystals is thus specified). The value of D ₁₀ is not specified as it is in no way critical. It was understood that the more the charges are fine (ie the lower the value of the D _i0 (for example a value of 100 nm or less)), the more interesting the products in question are. These granulometric data (D ₉₀ , D ₅ o (and Di ₀ )) are measured by means of a photon correlation optical particle size analyzer (PCS-DLS: Photons Correlation Spectroscopy-Diffusion Light Scattering), according to a procedure defined by the standard NF 11-666. They correspond respectively to the diameter for which the cumulative volume percentage (of the particles of charges) is equal to 90%, 50% (median diameter) (and 10%).

Such fine fillers are generally obtained by grinding "large" crystals. The skilled person knows many grinding processes, adapted to the sensitivity of the loads in question. We can in no way limit mention the possible use of SWECO ^® crushers. The Applicant has moreover described in the patent application FR 14 00669, published under No. 3,018,807 (September 25, 2015), an original grinding process for obtaining charges of CL20 submicron monomodal particle size. Said method comprises the continuous grinding of a charge of CL20 crystals, with a granulometry beyond the micron (D ₅₀ > 1 μιτι), in suspension in a liquid; said grinding being carried out, with cooling, by multi-pass the suspension in a circulation mill, horizontal axis, attrition with agitated grinding media.

The organic energy charges (whose presence rate, nature and particle size have been specified above) are therefore found in the composition of the composite explosive products of the invention, within an original binder.

Said binder is a polymeric gum:

chosen from among polyurethane-polyester gums (i.e. of polyurethane type with flexible segments of polyester type), polyurethane-polyether gums (i.e. of polyurethane type with flexible segments of polyether type) and their mixtures,

which has a number-average molecular mass of greater than 20,000 g / mol (advantageously greater than 35,000 g / mol, very advantageously greater than 75,000 g / mol (particularly with reference to the aging resistance of the final product)) , and

- which has a Mooney viscosity of between 20 and 70 ML

(5 + 4) at 100 ° C. This parameter is widely used in the rubber industry. "X ML (5 + 4) at 100 ° C" reads "x M equal to the viscosity in units (or points) Mooney; L or S (here L) corresponding to the size of the rotor, 5 indicating the preheating time of the product and 4, the time in minutes after starting the engine to which reading is taken, 100 ° C. being the temperature of the measurement ". The value "x" is usually given to "+/- y"; it is said value "x" that must be in the range 20-70 (including end values).

Such a rubber is perfectly suitable for the purposes of the invention, insofar as, in the proportions indicated (from 7 to 12% (advantageously from 8 to 10%) only, it is recalled that products with a high level of charge are involved. ):

1) it makes it possible to incorporate the high level of fine charges and to mechanically work the mixture (charges + binder) at low temperature, ie at a temperature below 120 ° C., generally below 100 ° C. (advantageously between 60 to 80 ° C. ° C) (temperature completely compatible with the stability of the present charges), and this, without use of solvent; and

2) it gives the final product (thin) the required mechanical properties: mechanical strength, cohesion, conformability. The products of the invention are conformable to the extent that said rubber is conformable. Reached at an adequate temperature, it can be shaped and then keep the shape in question. This form can only be modified by a new action of the temperature.

It is the merit of the inventors to have identified (selected) this type of binder, which is perfectly suitable for the purposes of the invention. Other types of binder have been tested and have not given satisfactory results (as to the possibility of obtaining the mixture, of working it at low temperature and / or as to the properties of the thin final product).

The binder of the products of the invention generally consists of a polyurethane-polyester gum or a polyurethane-polyether gum, but mixtures of at least two gums (at least two polyurethane-polyester gums, at least two polyurethane-polyether gums or at least two gums). less a polyurethane-polyester gum and at least a polyurethane-polyether gum; such mixtures of gums (gums within the meaning of the invention) constituting a gum within the meaning of the invention) having the required properties (referred to above) may be used. Said binder advantageously consists of a polyurethane-polyester gum.

The composition of the composite pyrotechnic products of the invention is capable of containing at least one plasticizer chosen from energetic plasticizers, non-energetic plasticizers and mixtures thereof; it may also contain in general up to 4% by weight of at least one such plasticizer. Such at least one plasticizer (= at least one energetic plasticizer, at least one non-energetic plasticizer or at least one energetic plasticizer and at least one non-energetic plasticizer) advantageously present (with reference to obtaining the product and its properties ), is generally at 1 to 4% by weight, preferably 2 to 3% by weight.

Said at least one plasticizer is therefore chosen from non-energetic plasticizers (for example, di-octyl azelate (DOZ), di-2-ethylhexyl sebacate (DOS), di-n-octyl phthalate (DOP), triacetin and mixtures thereof), energetic plasticizers (advantageously nitrate or nitramine type, for example, diethylene glycol dinitrate (DEGDN), triethylene glycol dinitrate (TEGDN), butanetriol trinitrate (BTTN), trimethylolethane trinitrate ( TMETN), a mixture of 2,4-dinitro-2,4-diaza-pentane, 2,4-dinitro-2,4-diaza-hexane and 3,5-dinitro-3,5-diaza-heptane ( and most particularly DNDA 5,7), nitrato ethyl nitramines (and especially methyl-2-nitratomethyl nitramine (methylNENA) and ethyl-2-nitratoethyl nitramine (ethylNENA)) and mixtures thereof.

The composition of the composite pyrotechnic products of the invention contains, according to a preferred variant, as a plasticizer, triethylene glycol dinitrate (TEGDN). The composition of the composite pyrotechnic products of the invention is therefore essentially constituted, or even constituted, of energetic charges, binder and optionally at least one plasticizer (advantageously present (see above)). It can consist of 100% by weight of said energy charges, said binder and said optional at least one plasticizer (charges + binder = 100% or charges + binder + plasticizer = 100%). It is generally at least 99% by weight. It can not be ruled out that it contains, in addition to the said charges, binding and optionally plasticizer (s), at least one additive. Such at least one additive, when present, is generally at 0.1 to 1% by weight. It may especially be at least one implementing agent (candellila wax and / or paraffin, for example).

The advantageous variants of the levels of fillers, binder and plasticizers indicated above are read independently or in combination.

According to one variant, the composition of the composite explosive products of the invention thus comprises:

+ from 88 to 90% of organic energy charges; said organic energy charges a) being selected from octogen (HMX), hexogen (RDX), hexanitrohexaazaisowurtzitane (CL20), pentrite (PETN) and mixtures thereof and b) having a particle size distribution with a value of of D ₉₀ less than 15 μηη and a value of D ₅ o less than or equal to 5 μm;

+ from 8 to 10%, of a polymeric gum chosen from polyurethane-polyester gums, polyurethane-polyether gums and mixtures thereof, the number-average molecular mass of which is greater than 20,000 g / mol (advantageously greater than 35,000) g / mol, most preferably greater than 75,000 g / mol) and whose Mooney viscosity is between 20 and 70 ML (5 + 4) at 100 ° C; + from 1 to 4%, advantageously from 2 to 3%, of a plasticizer chosen from energetic plasticizers, non-energetic plasticizers and mixtures thereof, and

+ from 0 to 1% of at least one additive.

In the context of this variant, said composition generally consists of what is specified.

With their characteristic composition specified above, the composite explosive products of the invention combine a small thickness. It is understood that a product of the invention has a thickness (e), a thickness (e) uniform, constant (controlled): 0.4 mm <e ≤ 5 mm, preferably 1 mm <e <2 mm. Very advantageously, e≤ 1.5 mm.

Obtaining products having a thickness of less than 0.4 mm is almost impossible, it would be necessary that such products can be effective (i.e. have a critical dimension of detonation below 0.4 mm).

Obtaining products with a thickness greater than 5 mm is of little value (the products in question being effective at 5 mm or even at a lower thickness) and poses, in any event, problems as to the conformability said products, as for the control of their thickness greater than 5 mm.

Considering the thickness values indicated above (0.4 mm ≤ e 5 5 mm, advantageously 1 mm e e 2 2 mm, very advantageously ≤ 1.5 mm), the person skilled in the art understands all the It is up to the inventors to propose such high performance composite explosive products (the explosive in question must therefore necessarily have a critical dimension of detonation below these low values) and the appropriate mechanical properties (mechanical strength, cohesion, conformability). The good results obtained are essentially based on the binder (the nature of the binder) which, combined with a adequate process (see below), authorizes the incorporation within it of a high rate of charges ("sensitive") of fine particle size.

The composite pyrotechnic products of the invention, as described above (having the composition specified above and the thin thickness specified above), may have any type of shape and may be in particular:

(a) in the form of leaves (we can speak of films if the leaves in question have a "great" length),

b) in the form of cut-out elements in a sheet without recess cut-out passing through the thickness of said sheet (said elements consist of pieces of sheets, such as (strips, bars, for example) or possibly worked on a part (only part) of their thickness), or

c) in the form of cut-out elements in a sheet with recess cut-out (s) through the thickness of said sheet

(said elements being capable of presenting any geometry).

The cuttings in question are conventional cuttings, implemented with conventional mechanical means (advantageously cutting by jet (s) of water, with two parallel blades or die cutter).

The composite pyrotechnic products of the invention can thus notably consist of:

(a) an explosive film (usable in particular as a demolition material, as a cutting material, as a metal-forming material, etc.) (see point (a) above),

b) into an explosive bar with a V-groove (usable as part of a detonating cutting line, said V-groove being intended to be covered with a metallic coating or a coating loaded with metallic particles) (see point (b) above), or (c) a miniaturized multi-point explosive charge initiation network (see (c) above).

The latter type of products of the invention is particularly preferred. The channels of the miniaturized network obviously have a minimum section equal to the critical dimension of detonation of the composition in question. They may exhibit directional changes with high angles up to 90 ° (in view of the low values of said critical dimensions). They generally have a square or rectangular section.

Such networks according to the invention are particularly interesting. Their conformability (inherent to the nature of the binder present in their composition and their small thickness) allows their use both on flat surfaces (one can conventionally initiate a cylindrical shaped load with such a network positioned on one of the bases of the load) only on curved surfaces (such unconventional positioning may be particularly interesting for increasing the speed of flashes in one direction).

According to its second object, the invention relates to a method for preparing (obtaining) composite pyrotechnic products of the invention, as described above. Said method is based, typically, on the use of at least one roll mill. It typically comprises incorporating the charges into the binder in a roll mill. It includes, more precisely:

the incorporation of the fillers into the eraser raised to a temperature of at least 50 ° C., generally at a temperature between 60 and 80 ° C .; said incorporation being carried out in a roll mill, and

the calendering of the resulting filled sheet in a roller mixer. Any plasticizer and intervening additive is also incorporated into the gum in the roll mill.

The roller mixer is a known Persian device. Its use has made it possible to obtain the products of the invention (it has made it possible to incorporate the high level of small charges into the gum), it has made it possible to obtain the said advantageously (without using a solvent (this is very advantageous compared to certain processes of the prior art) at temperatures compatible with the sensitivity of the charges, mixing and rolling being provided in a single step, at the same station (this is very advantageous compared to some processes of the prior art)).

It can be considered that the present invention is based on the selection of the binder associated with the selection of the process, this dual selection making it not only possible to obtain the products of the invention (products heavily loaded with fine sensitive fillers) possible (the feasibility of said process was not acquired in advance) but possible under simple implementation conditions.

The formation of the mixture in the roll mixer is conventionally carried out with the rolls rotated in opposite directions at different speeds.

The gum, when it is in the form of granules, is first of all roughly shaped to the mill to obtain a thin strip (1 mm to a few mm).

Said gum is generally first introduced into the roll mixer, the rolls of which are brought to a temperature (T) of at least 50 ° C. (below 120 ° C., generally below 100 ° C.), advantageously between 60 and 80 ° C (60 ° C≤T≤80 ° C), for example 70 ° C. The fillers and any other ingredient (s) (possible plasticizer (s) and additive (s)) are then introduced separately or as a mixture. It is generally carried out beforehand a mixture fillers + ingredient (s), when at least one such ingredient is involved, and then introducing said mixture. The introduction of the charges can conveniently be carried out in several sequences after a setting of the spacing of the rolls. The coating formed around the fastest rotating cylinder can be recovered (cut with a cutter), folded and reintroduced between the cylinders (in order to homogenize the distribution of charges), according to the usual methods applied to this process.

A sheet (a film) of small thickness (corresponding to the spacing between the rolls) is thus obtained. For adjusting said thickness to the desired value (0.4 mm <e ≤ 5 mm, advantageously 1 mm <e <2 mm, very advantageously ≤ 1.5 mm), or even for the simple elimination of unevenness in thickness (It aims a constant thickness, uniform, perfectly controlled), said sheet is calendered in a roll mill (the rolls of said roll mixer then rotating in the same direction, at the same speed, and their spacing being set to the value of desired thickness, or to a lower value because two phenomena are likely to occur: the material may force the spacing of the rolls and there may be a relaxation of the product after rolling).

It is conceivable that the successive steps of the method of the invention

- Obtaining the mixture in the form of a thin product (sheet) and calendering - are very advantageously implemented with the same cylinder mixer. Thus, at the same station, it performs mixing, rolling and calendering; thus, at the same station, one can directly obtain a product of the invention sheet type (desired product or can be used to prepare, including cutting, other desired products of the invention).

The method of the invention may therefore comprise, in addition, the cutting, advantageously by jet (s) of water, with two parallel blades or punch, the calendered filled sheet. This produces cut elements as specified above. We have seen that said cut elements can further be worked.

The cutting of the leaves, more particularly with blades, can be facilitated by previously heating said sheets between 40 and 50 ° C.

I. It is now proposed to illustrate the invention, in no way limiting, in these aspects of product and process, by the examples below.

1. Raw materials used

A) The gums:

. UREPAN ^® G 643: sold by RheinChemie company (polyaddition product of diphenyl-methane diisocyanate and a polyester). It has the following characteristics:

Number average molecular weight: 80,000 g / mol

Mooney viscosity: 40 (+/- 10) ML (5 + 4) at 100 ° C.

. UREPAN ^® 600: sold by RheinChemie company (polyaddition product of toluene diisocyanate and a polyester). It has the following characteristics:

Number average molecular weight: 40,000 g / mol

Mooney viscosity: 26 (+/- 6) ML (5 + 4) at 100 ° C. B) The charges:

The hexogen (RDX) is that marketed by the company EURENCO under the reference RDX M3c (D _i0 = 1 pm, D ₅₀ = 4 pm and D ₉₀ = 9 pm).

Hexanitrohexaazaisowurtzitane (CL20) is prepared and finely ground before use. Its particle size cut is characterized as follows: Di ₀ = 0.5 μm, D ₅₀ = 4.7 μm and D ₀ = 12.2 μm.

2. Process for the preparation of composite pyrotechnic products of the invention

Composite pyrotechnic products of the invention were prepared and tested as follows.

Their mass composition and their critical diameter of detonation (measured) are respectively given in the table below.

These composite pyrotechnic products of the invention were obtained from the raw materials identified above.

Step a of the process: pasty mixtures were obtained in a roll mill, in a known Persian manner. To obtain each of said mixtures, the gum concerned was first introduced between the rolls, brought to a temperature of 70 ° C. It has been softened. Then, a mixture + plasticizer charges, previously made in a container, was added. According to Example 8, only the charges were added. When all the charges were incorporated into the gum, the mixture was continued for about 15 minutes. At this stage (see Example 1), it has been possible to incorporate candelilla wax in a very gradual manner in a small amount (0.3% according to said example 1) in order to lubricate the loaded gum and the cylinders. After incorporation of the wax, mixing was continued for five minutes. A coating of one of the cylinders was then obtained. Finally, the rotation of the rolls was stopped and the coating was cut in its width in order to recover it in the form of a sheet (dimensions: 250 mm × 150 mm). The sheets obtained had, according to the spacing of the rolls, Thickness of about 2 mm, 1.5 mm or 1 mm.

Step b of the process: a calendering was implemented for an adjustment and / or a uniformization of the thickness of the sheets obtained. Said sheets were passed between the two cylinders of the same cylinder mixer, set to the desired spacing, rotating in the same direction at the same speed. This time, there was no winding of leaves around a cylinder. There was implemented a calendering. Once the calender phase was complete, the product obtained in sheet form was homogeneous and had a constant thickness (of 2 mm, 1.5 mm or 1 mm).

Step c of the process: the cutting into channels of different sections was achieved through a specific tool, consisting essentially of two parallel blades whose spacing is guaranteed by washers of calibrated thicknesses. The leaves were cut after being heated to 45 ° C. 3) Results

The compositions of Examples 1, 2 and 3, containing RDX fillers, are particularly interesting in that they have a critical detonation section less than or equal to 1 mm ² .

The compositions of Examples 6 and 7, containing charges of CL20, have higher critical detonation sections (the critical detonation section of the composition of Example 6 is greater than 1.5 mm ² and the critical detonation section of the composition of Example 7 is between 1 and 1.5 mm ² ) than those of Examples 1, 2 and 3 containing RDX fillers. The increase in the charge rate logically leads to a decrease in the critical detonation section (the charge rate of the composition of Example 6 is

86% while the load ratio of the composition of Example 7 is

87%). II. The interest of the present invention is also apparent from the consideration of the following remarks. a) Binder = PBHT (marketed by the company CRAY VALLEY under the name: R45HT) with a number-average molecular weight of 2800 g / mol (binder conventionally used in the context of composite energy products). al) Pastes (very viscous) have been obtained by kneading, from said binder (20% by weight) and RDX charges (80% by mass), reference M3c from EURENCO, whose particle size distribution had a value of Dm of 1 μιτι, a value of D ₅₀ of 4 pm and a D ₉₀ value of 9 pm (see above). They were cast, with difficulty, (in small thicknesses) in PMMA molds (stepped specimens) and tested in said molds (any moldings involving alterations) for evaluation of their critical section. Said critical section was of the order of 3 mm ² . a2) Pastes of the same type (highly viscous), containing, in addition to the PBHT and fillers, an effective amount of a crosslinking agent (diisocyanate), were prepared by kneading. They were cast in molds to be in the form of sheets of low thickness. Said sheets have been heat treated for the crosslinking of PBHT (via its telechelic hydroxy functions). The shrinkage that occurred during the crosslinking failed to control the thickness of the crosslinked sheets. In fact, in order to obtain controlled thin sheets (2 mm, for example), it was necessary to proceed as follows: to obtain, by molding, sheets of substantial thickness (for example 10 mm thick), treat them thermally then machine them to said small controlled thickness. a3) It was not possible to obtain by kneading pasta containing in said binder more than 80% by mass of small RDX fillers (Dio = 1 μm, D ₅₀ = 4 μm and D ₉₀ = 9 μm; M3c of EURENCO (see above)). a4) An RDX loading rate of 85% by mass, in said binder (15% by mass), could only be obtained by using several particle sizes of RDX charges: 65% by mass of RDX, reference M3c EURENCO (see above) and 20% by mass of RDX of larger particle size (D ₅ o = 35 pm). Pasta obtained however could not be rolled between rolls, given their stickiness. They were cast (in small thicknesses) in PMMA molds (stepped test pieces) and tested in said molds (any moldings involving alterations) to evaluate their critical section. Their critical section, given the presence of large RDX charges, was greater than 5 mm ² . b) Binder = lauryl methacrylate

This binder, very liquid, allowed the incorporation of a high rate of small charges within it. However, it must be cross-linked. Pasta containing 14% by weight of lauryl methacrylate (+ crosslinking agent: diisocyanate) and 86% by weight of CL20 (whose particle size distribution had a Dio value = 0.5 μm, a value of D ₅₀ = 4, 7 pm and a value of D ₉₀ = 12.2 pm (see above)) were prepared. They were cast in molds to be in the form of sheets of low thickness. Said sheets have been heat-treated for the crosslinking of lauryl methacrylate. The shrinkage that occurred during crosslinking did not allow to control the thickness of the crosslinked sheets. In fact, in order to obtain controlled thin sheets (2 mm, for example), it was necessary to proceed as follows: to obtain, by molding, sheets of substantial thickness (for example 10 mm thick), treat them thermally then machine them to said small controlled thickness.

Claims

Composite explosive product, characterized in that:

- its composition, expressed in mass percentages, contains:

+ from 85 to 92%, advantageously from 88 to 90%, of organic energy charges; said organic energy charges a) being selected from octogen (HMX), hexogen (RDX), hexanitrohexaazaisowurtzitane (CL20), pentrite (PETN) and mixtures thereof and b) having a particle size distribution with a value of of D ₉₀ less than 15 μηι and a value of D ₅₀ less than or equal to 5 μιη; and

it has a thickness of 0.4 to 5 mm, advantageously 1 to 2 mm.

2. composite explosive product according to claim 1, characterized in that said energetic charges are selected from charges of hexogen (RDX), hexanitrohexaazaisowurtzitane (CL20) and mixtures thereof.

3. Composite explosive product according to claim 1 or 2, characterized in that said polymeric gum is a polyurethane-polyester gum or a polyurethane-polyether gum, preferably a polyurethane-polyester gum.

4. Composite explosive product according to any one of claims 1 to 3, characterized in that said polymeric gum has a number average molecular weight greater than 35 000 g / mol, very advantageously greater than 75 000 g / mol.

5. composite explosive product according to any one of claims 1 to 4, characterized in that its composition also contains at least one plasticizer, selected from energetic plasticizers, non-energetic plasticizers and mixtures thereof; said at least one plasticizer being generally present in a proportion of 1 to 4% by weight, advantageously in a proportion of 2 to 3% by weight.

6. composite explosive product according to any one of claims 1 to 5, characterized in that its composition also contains at least one additive; said at least one additive being generally present in a proportion of 0.1 to 1% by weight.

7. composite explosive product according to any one of claims 1 to 6, characterized in that it is in the form of a sheet or a cut element in a sheet without recess cutting through in the thickness of said sheet, or of a cut-out element in a sheet with recess cutout (s) passing through the thickness of said sheet.

8. composite explosive product according to claim 7, characterized in that it consists of an explosive sheet, an explosive bar with a V-groove or a miniaturized ignition network multipoint explosive charges.

9. Composite explosive product according to any one of claims 1 to 8, characterized in that it consists of a miniaturized ignition system multipoint explosive charges, suitable for use on a flat surface or on a curved surface of said explosive charges .

10. Process for obtaining a composite explosive product according to any one of claims 1 to 9, characterized in that it comprises:

incorporating said fillers into said gum heated to a temperature of at least 50 ° C, advantageously at a temperature between 60 and 80 ° C .; said incorporation being carried out in a roll mill, and

the calendering of the resulting filled sheet in a roller mixer.

11. Production method according to claim 10, characterized in that it further comprises:

- Cutting, advantageously by jet (s) of water, with two parallel blades or punch, the calendered filled sheet.