Note: Descriptions are shown in the official language in which they were submitted.
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Igniter mixtures
The present invention relates to igniter
mixtures, their preparation and their use.
Igniter mixtures or else igniter compositions
are used to ignite pyrotechnic mixtures or compositions
and propellant charges. The pyrotechnic mixtures or
compositions may in this connection be the sole charge
or else an ignition booster charge or a gas-generating
composition. Propellant charges/gas compositions are
converted mainly into gaseous constituents which can be
employed to initiate processes which take place
rapidly, such as, for example, the acceleration of
projectiles, the driving in of fixing materials, for
example with the aid of bolt-firing tools, or else the
inflation of gas bags (airbags) or to trigger belt
tighteners in motor vehicle safety. One variant is
represented by the use of liquid/gas compositions in
place of solid/gas compositions. They make use of the
reaction of liquid fuel with oxidizing agents to
generate gas.
Igniter mixtures are generally initiated mecha-
nically and must therefore be sensitive to friction and
impact. They generally consist of initiator or primary
explosives such as, for example, lead styphnate or
diazodinitrophenol, reducing agents such as metal
powders, and oxidizing agents such as barium nitrate or
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zinc peroxide. Sensitizers such as tetrazene or
abrasives such as glass powder, which increase the
sensitivity of the initiator explosives are likewise
employed. For electrically ignitable systems it is
primarily the rapidly reacting initiator explosives
which are employed. The high mechanical sensitivity of
the constituents, which is necessary for satisfactory
functioning, is, however, a disadvantage in the manipu-
lation of the raw materials and mixtures. It requires
special safety measures. Other types of ignition such
as ignition by exposure to heat or by feeding in high-
frequency electromagnetic waves do not solve this
problem, or are suitable only for very specific,
greatly restricted applications.
The object of the present invention was to
provide novel igniter mixtures.
In a first embodiment of the invention, the
object is achieved by igniter mixtures which can be
ignited by laser light. The explosives which may be
present in the novel igniter mixtures are primary or
initiator explosives, secondary explosives or mixtures
of these explosives. Examples of primary or initiator
explosives which can be employed are lead styphnate,
diazodinitrophenol, tetrazene or potassium dinitro-
benzofuroxanate or mixtures of these explosives.
Suitable secondary explosives are selected from nitro-
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cellulose, hexanitrostilbene, nitrated aromatic com-
pounds and/or nitrated aromatic compounds with a
polymeric structure such as polynitropolyphenyl ethers
or the' polynitropolyphenylenes,. from certain
heterocycles such as nitrotriazolone, from the
derivatives of the tetrazoles such as aminotetrazole,
ditetrazole or diaminoguanidine-azotetrazole and from
hexogen or octogen. Further secondary explosives which
can be employed are those derived from urea and its
derivatives. Examples;which may be mentioned here are
the urea derivatives biuret, guanidine, nitroguanidine,
guanidine nitrate, aminoguanidine, aminoguanidine
nitrate, thiourea, triaminoguanidine riitrate, amino-
guanidine hydrogen carbonate, azodicarbonamide,
tetrazene, semicarbazide nitrate, and the urethanes,
the ureides such as barbituric acid and its
derivatives. Said explosives can be employed alone or
as mixture. Preferred according to the invention are
the secondary explosives, particularly preferably the.
nitrated aromatic compounds with a polymeric structure,
especially the polynitropolyphenyl ethers and the
polynitropolyphenylenes or mixtures of these secondary
explosives.
In accordance with another aspect, the present invention relates to
ignition mixture that is ignitable by laser light and that contains oxidizing
and
reducing agents and a secondary
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explosive, wherein the secondary explosive is selected form the group
consisting of polynitrophenylether, polynitropolyphenylenes, nitrocellulose,
hexanitrostilbene, nitrotriazolone, aminotetrazoles, ditetrazoles,
diaminoguanidine azotetrazoles, hexagene, octagene, biuret, guanidine,
nitroguanidine, guanidine nitrate, aminoguanidine, aminoguanidine nitrate,
thiourea, triaminoguanidine nitrate, aminoguanidine hydrogen carbonate,
azodicarboxylic acid diamide, tetrazene, semicarbazidenitrate, urethanes,
barbituric acids and mixtures thereof.
In accordance with a further aspect, the present invention relates to an
ignition mixture that is ignitable by laser light and that contains a
secondary
explosive, an oxidizer, a reducing agent and a binder, wherein
the secondary explosive is selected from the group consisting of
polynitrophenylether, polynitropolyphenylenes, nitrocellulose,
hexanitrostilbene,
nitrotriazolone, aminotetrazoles, ditetrazoles, diaminoguanidine
azotetrazoles,
hexagene, octagene, biuret, guanidine, nitroguanidine, guanidine nitrate,
aminoguanidine, aminoguanidine nitrate, thiourea, triaminoguanidine nitrate,
aminoguanidine hydrogen carbonate, azodicarboxylic acid diamide, tetrazene,
semicarbazidenitrate, urethanes, barbituric acids and mixtures thereof.
the oxidizer is selected from the group consisting of sulphur, the
peroxides of alkali metals or alkaline earth metals, zinc peroxide,
peroxodisulfates of alkali metals or alkaline earth metals, ammonium from the
nitrates of alkali metals and alkaline earth metals, oxohalogen compounds of
alkali metals or alkaline earth metals, ammonium, and mixtures thereof, and
the reducing agent is selected from the group consisting of a
metals selected from the group consisting of titanium, zirconium, aluminium,
magnesium, cerium, and a mixture of these metals, an alloy of these metals
carbon, boron, and mixtures thereof.
In accordance with a still further aspect, the present invention relates to
an ignition mixture that is ignitable by laser light and that contains a
secondary
explosive, an oxidizer, a reducing agent and a binder, wherein
the secondary explosive is polynitrophenylether,
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the oxidizer is potassium nitrate,
the reducing agent is boron, and
the binder is polyurethane.
Besides the explosives, the novel igniters also
comprise oxidizing and reducing agents customary per
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se. Binders, processing and/or compression auxiliaries
can likewise be employed where appropriate.
Oxidizing agents which can be employed are the
peroxides of the alkali metals and alkaline earth
metals, zinc peroxide, and the peroxodisulfates of said
elements and of ammonium, nitrates of the alkali metals
and alkaline earth metals, especially lithium, sodium,
potassium or strontium nitrate, and ammonium nitrate,
oxohalogen compounds of the alkali metals or alkaline
earth metals or of ammonium, particularly preferably
potassium perchlorate or ammonium perchlorate. Sulfur
is likewise suitable as oxidizing agent. Said oxidizing
agents can be employed alone or as mixture.
Reducing agents employed according to the
invention are metals such as, for example, titanium,
zirconium, aluminum, magnesium, cerium in finely
powdered form. Alloys of these metals such as titanium/
aluminum or cerium/magnesium can also be employed
according to the invention. Further reducing agents are
carbon or boron. Said reducing agents can be employed
alone or as mixture.
Binders which can be employed are compounds
from the group of polyesters or of polyurethanes.
Compounds with binding properties which make a contri-
bution to the heat of the explosion and/or to the
oxygen balance, for example nitrocellulose or poly-
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nitropolyphenylene, can likewise be employed as
binders.
Processing and compression aids can be sub-
stances which, for example, increase the flowability,
such as Aerosil, or substances which prevent dust
formation and improve the blocking resistance or
meterability, such as graphite or boron nitride.
To improve absorption of the laser light, the
novel igniter mixtures can where appropriate be colored
or mixed with colored pigments. The thermal stability
can, if necessary, be improved by adding stabilizers.
Suitable examples thereof are substances which are
employed for stabilizing nitrocellulose.
It is further possible to add burning
moderators to influence the burning rate of the novel
igniter mixtures.
The burning moderators employed are substances
or mixtures thereof which are suitable for influencing,
by heterogeneous or homogeneous catalysis, the burning
and its rate. Moderators which intervene in the
reaction in the form of a heterogeneous catalysis are
metals, metal oxides and/or metal carbonates and/or
metal sulfides. Metals which can preferably be employed
are boron, silicon, copper, iron, titanium, zinc or
molybdenum. It is also possible to employ calcium
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carbonate. Mixtures of these moderators can likewise be
used.
Moderators which intervene in the reaction in
the form of a homogeneous catalysis are, for example,
sulfur, copper resorcylates or ferrocene and its
derivatives. These moderators are vaporized by the
temperatures arising during the reaction and may thus
intervene in the reaction themselves or as secondary
products.
For protection from environmental effects, the
novel igniter mixtures may, where appropriate, be
treated or coated with protective agents.
The novel igniter mixtures have a wide variety
of possible uses. They are preferably used for igniting
pyrotechnic mixtures or compositions and propellant
charges employed to initiate processes which take place
rapidly, such as, for example, the acceleration of
projectiles, the driving in of fixing materials, for
example with the aid of bolt-firing tools, or else the
inflation of gas bags (airbags) or for triggering belt
tighteners in motor vehicle safety.
The characteristic safety data of some of the
novel igniter mixtures are shown in Table 2. The data
were determined by the methods of the Bundesanstalt fur
Materialprufung [German Materials Testing Agency].
Compared with the primary explosive lead styphnate, in
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particular the sensitivity to friction and impact are
distinctly improved with the novel igniters.
To estimate important characteristic quantities
of the novel igniter mixtures, such as the energy
released during the reaction (heat of explosion), the
pressure, the explosion temperature and the reaction
products arising at this temperature, a thermodynamic
computer program was used to calculate an adiabatic
reaction for the novel igniter mixtures at constant
volume and a charge density of 0.1 g/cm3. Table 3 shows
the most important data from the thermodynamic calcula-
tion. The ignition energy necessary to initiate a
reaction was determined experimentally.
The following examples are intended to illus-
trate the invention without restricting it.
Examples 1 to 16:
The novel igniter mixtures are produced by
processes known per se. The individual components are
screened in the mixing ratios indicated in Table 1
through a screen with a mesh width of 0.2 mm and mixed
in a tumbler mixer for 30 minutes. 200 mg portions of
these mixtures are compressed under a force of 71 N/mm2
to tablets with a diameter of 6 mm. The tablets
produced in this way are ignited with a laser beam
(wavelength 1060 nm), with a radiant energy of about
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200 mJ and a pulse length of 2.5 ms. The ignition
behavior is shown in Table 1.
Table 1
Examples 0
Component 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 %D
KNO3 52.5 52.5 33.3 32.3 33.3 40 40
B 18.8 18.8 2.9 2.9 10 10
Binder 3.7 3.7
NPE 25 45 44.7 44.5 44.1 66.7 64.8 66.7 64.8 25 50
PNP 25 100 66.7 50 25
Zn02 50 49.6 49.6 49 33.3 32.3
Ti 5 4.9 4.9 4.9
Graphite 0.5 1 2
Black powder 75 75
Ignition +++ + + + + + + ++ + + + +++ +++ + + +++ behavior
+ = ignition
++ = good ignition
+++ = very good ignition
Components employed:
KNO3 potassium nitrate < 200 m NPE polynitropolyphenyl ether
B boron, amorphous PNP polynitropolyphenylene
Ti titanium metal powder < 40 m Zn02 zinc peroxide, average particle size 6.5
m, oxygen ro
content 13.5%
Binder polyurethane
~ 'p'
Table 2 0
Sample Pressure T Heat of ex. Condensate Ignition
L%
[atm] [K] [cal/g] content energy
[%/mol] [Mi]
NPE 1109 2932 686 0 = 10
NPE/KNO3 66.7/33.3 907.4 3073.5 672 7.5 160
NPE/Zn02/Ti 45/50/5 1198 4146 978 14.6 = 200 -
Black powder/NPE 75/25 490 2290 -179 11.6 = 200 i o
AZM 0 9531/NPE 75/25 622 3265 815 52 = 200
NPE/KN03/B 50/40/10 843 3374 673 29 = 90
NPE/Zn02 66.7/33.3 1341 4044 1016 7 > 200
NPE/Zn02/B 64.8/32.3/2.9 1194 3731 981 14 > 200
NPE/KNO3/B 64.8/32.3/2.9 1002 3382 752 2 = 100
ro
NC/KNO3 66.7/33.3 872 3282 883 11 no ignition
Lead styphnate 663 3639 550 10 = 5
ro
-4
F-+
L%
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Table 3
Explosive Friction Impact Explosion
sensitivity sensitivity point
[N] [J] [ C]
Lead styphnate 2 0.025 280
AZM 0 2956 > 360 5 > 400
AZM 0 9531 360 4 > 400
Black powder 360 5 > 400
HITP (based on 360 15-50 > 400
aminotetrazole)
NPE >_ 360 7.5 > 260
NPE/Zn02/Ti 360 15 230
NPE/Zn02 240 20 235
NPE/KN03 = 3% B 160 4 decomposition
from 230
PNP/KNO3 > 360 10 293
PNP/KN03/B >_ 360 10 293
