Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B23/00—Compositions characterised by non-explosive or non-thermic constituents
  • C06B23/04—Compositions characterised by non-explosive or non-thermic constituents for cooling the explosion gases including antifouling and flash suppressing agents
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B25/00—Compositions containing a nitrated organic compound
  • C06B25/18—Compositions containing a nitrated organic compound the compound being nitrocellulose present as 10% or more by weight of the total composition
  • C06B25/24—Compositions containing a nitrated organic compound the compound being nitrocellulose present as 10% or more by weight of the total composition with nitroglycerine

Definitions

• the present invention relates to a method for manufacturing a propellant or double-base propellant by the molding method, and to a composition obtained by this method.
• It relates more particularly to a process for manufacturing a double-base propellant with a low temperature coefficient and low emission of flame glow.
• a double-base propellant essentially comprises two energetic constituents, namely a cellulose nitrate, such as, for example, nitrocellulose, and a nitrated oil, such as, for example, nitroglycerin.
• compositions can be manufactured by various processes, such as the process without dissolving with extrusion of the composition, or the so-called molding process.
• This latter process consists in producing a molding powder containing nitrocellulose to which ballistic additives, plasticizers and possibly a small proportion of nitrated oil are added, then in gelatinizing this powder with a molding solvent, consisting of nitrated oil. and an inert solvent such as triacetin having as a function of phlegmatizing the nitrated oil.
• a molding solvent consisting of nitrated oil.
• an inert solvent such as triacetin having as a function of phlegmatizing the nitrated oil.
• the molding powder is placed in a mold, then the molding solvent is fed into it until the powder is completely submerged.
• the molded propellant block is then subjected to a heat treatment to complete the gelatinization of the nitrocellulose.
• combustion catalysts which accelerate the rate of combustion of the propellant.
• These catalysts are generally lead or copper salts, and acetylene black.
• ballistic modifiers which do not act on the combustion speed, but on the operating conditions of the propellant and in particular, the composition and the temperature of the combustion gases.
• these additives can in particular be anti-glare agents attenuating flame glows.
• combustion gases can contain compounds which are not fully oxidized and which, in contact with the oxygen in the air at the outlet of the propellant nozzle, can ignite. This phenomenon is generally called post-combustion.
• salts are added which prevent them from re-igniting. These salts are generally incorporated into the propellant and entrained in the gases during of its combustion.
• the propellants thus obtained have satisfactory ballistic properties.
• temperature coefficient of a propellant means the rate of change of the combustion speed for a temperature rise of 1 ° C. This value is one of the characteristics of a propellant composition.
• a propellant with a low temperature coefficient can be used in any temperature condition, its combustion rate remaining substantially constant.
• a nozzle is said to be suitable if its shape and its dimensions make it possible to obtain a pressure of the combustion gases at the outlet of the nozzle substantially equal to the ambient pressure.
• the object of the present invention is in particular to propose a process for manufacturing a double-base propellant having a low and even negative temperature coefficient, while not exhibiting a flame glow and retaining a level of ballistic properties similar to that equivalent propellants that do not contain anti-glare agents.
• the invention provides a method of manufacturing, by the so-called molding method, a double-base propellant composition containing ballistic additives and consisting in molding a nitrocellulose-based molding powder with a solvent for molding.
• base of a nitrated oil in which the molding powder consists of a mixture of at least two powders, one of which, the first, contains anti-glare agents, characterized in that said first powder contains at most 25 % by weight of anti-glare agents, the weight ratio between said first and said second powder in the molding powder being between 15/85 and 50/50.
• the first powder comprises at least 5% by weight of anti-glare agents, advantageously between 5 and 20% by weight.
• the first and said second powder also contain, as ballistic additives, combustion catalysts.
• combustion catalysts can be contained only in the second powder.
• the aforementioned second powder has a low and preferably negative temperature coefficient.
• the use of a powder not loaded with anti-glare agents, called the second powder, and a powder loaded at a low rate with anti-glare agents called the first powder makes it possible to obtain a propellant composition having a coefficient of temperature substantially close to that of the second powder.
• the level of combustion speed of the propellant composition according to the invention is substantially equal to that of an equivalent composition not containing anti-glare agents.
• the anti-glare effect is reinforced, since there is no longer any post-combustion phenomenon during the combustion of the propellant, even under severe operating conditions, and in particular during combustion with an unsuitable nozzle, or presenting obstacles in its divergent.
• Both the first and the second powder may contain other ballistic additives, such as anti-instability agents, energetic agents such as nitramines.
• ballistic additives we generally mean all the compounds added to a propellant and influencing either the combustion of the latter, these additives are called combustion catalysts, either the flame or the properties of gases such as anti-instability agents, energetic agents, anti-glare agents, these additives are called agents which do not catalyze combustion.
• combustion catalysts commonly used in double-base propellants and already known to those skilled in the art are suitable for the invention.
• combustion accelerator of acetylene black, lead salts, copper salts such as lead oxides, copper oxides, salicylates, octoates, stearates and resorcylates. lead or copper.
• SAIB sucrose acetoisobutyrate
• OAS sucrose octoacetate
• anti-glare agents suitable for the invention there may be mentioned, by way of example, potassium sulphate, potassium nitrate, potassium hydrogen tartrate or aluminum and potassium fluoride also called cryolite. This list is not exhaustive and is given for information only.
• the molding powder in other words the first and / or second powders constituting it, also contains a nitrated oil, nitroglycerin being the most used oil. It can also contain a plasticizer such as dioctyl phthalate, for example.
• the content by weight of anti-glare agent is preferably less than or equal to 20% in the first powder.
• powders A to L are prepared, according to a conventional method, consisting in dissolving dehydrated nitrocellulose in an ether-alcohol or acetone-alcohol solvent. Then during the kneading phase, a plasticizer, ballistic additives and possibly a nitrated oil and a stabilizer are added. The dough thus obtained is then stretched, extruded in the form of grains allowing good filling of the mold, then wrung and possibly soaked, dried, and mixed.
• molding powders are prepared by mixing two or more of the powders A to J above, for example in a bezel for 15 minutes.
• each molding powder thus obtained is then placed in a mold and then gelatinized with a molding solvent of the following composition: the filling rate, for each composition prepared is 60%.
• filling rate is meant the ratio of the mass of powder supplied to the mold to the mass of the finished propellant.
• composition obtained is then subjected to a usual heat treatment.
• compositions are tested in bench shooting with unsuitable nozzles and containing a jet interceptor located in the exit plane.
• the jet interceptor closes approximately 30% of the nozzle divergent outlet area.
• compositions tested have a potential of approximately 3553 joules / g and burn at a combustion rate of approximately 9 mm / s at a pressure of approximately 8 MPa.
• Tests 1,2,3 are comparative tests and correspond to the process described in American patent n ° 3960621. The results show that the afterburner phenomenon is not eliminated, even in test 3, the molding powder of which has was obtained with a high proportion of powder (C) loaded with an anti-glare agent.
• the invention is not limited to the examples.
• the contents of nitrocellulose, nitroglycerin, plasticizer or combustion catalysts in the molding powder are not critical, it is the same for the filling rate and the composition of the molding solvent.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Emergency Medicine (AREA)
• Medicinal Preparation (AREA)
• Air Bags (AREA)
• Lubricants (AREA)
• Cosmetics (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)

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• 1985
  • 1985-10-14 FR FR8515170A patent/FR2588551B1/fr not_active Expired
• 1986
  • 1986-10-07 US US06/916,308 patent/US4701228A/en not_active Expired - Lifetime
  • 1986-10-08 IL IL80259A patent/IL80259A/xx not_active IP Right Cessation
  • 1986-10-09 GR GR862532A patent/GR862532B/el unknown
  • 1986-10-09 EP EP86402235A patent/EP0219431A1/fr not_active Withdrawn
  • 1986-10-10 CA CA000520299A patent/CA1288950C/fr not_active Expired - Lifetime
  • 1986-10-12 EG EG63886A patent/EG19988A/xx active
  • 1986-10-14 JP JP61242179A patent/JPS6287476A/ja active Pending

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