U.S. patent application number 14/783918 was filed with the patent office on 2016-02-18 for electrically ignitable caseless propellant charge, the production and use thereof.
The applicant listed for this patent is FISCHERWERKE GMBH & CO. KG. Invention is credited to Willi HAUG, Meinrad ZEH.
Application Number | 20160046536 14/783918 |
Document ID | / |
Family ID | 50693605 |
Filed Date | 2016-02-18 |
United States Patent
Application |
20160046536 |
Kind Code |
A1 |
HAUG; Willi ; et
al. |
February 18, 2016 |
ELECTRICALLY IGNITABLE CASELESS PROPELLANT CHARGE, THE PRODUCTION
AND USE THEREOF
Abstract
Electrically ignitable caseless propellant charge in the form of
a caseless propellant tablet (5), characterised in that it is
obtainable by mixing together of at least one current-conductive
material in dissolved or dispersed form or powder form and graphite
in powder form, together with nitrocellulose, with or without
addition of further additives, and subsequent compaction to form a
propellant tablet, the production and use thereof, and related
subject matter of the invention. Uses include: use of the
propellant charge in a bolt-driving tool for installing bolts, as
an explosive charge in a warning shot device, as a gas-generating
element in airbags, for driving cutting devices, for driving
pressing devices (for example for squeezing tong-like elements
together) or as a propellant charge in small calibre rifles for
sporting purposes, or for captive bolt devices for animal
slaughtering.
Inventors: |
HAUG; Willi;
(Freudenstadt-Musbach, DE) ; ZEH; Meinrad;
(Weitnau-Seltmans, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FISCHERWERKE GMBH & CO. KG |
Waldachtal |
|
DE |
|
|
Family ID: |
50693605 |
Appl. No.: |
14/783918 |
Filed: |
April 14, 2014 |
PCT Filed: |
April 14, 2014 |
PCT NO: |
PCT/EP2014/000994 |
371 Date: |
October 12, 2015 |
Current U.S.
Class: |
149/2 |
Current CPC
Class: |
C06B 25/18 20130101;
C06B 33/00 20130101; C06B 23/001 20130101; C06B 25/20 20130101;
C06B 29/20 20130101; C06B 23/007 20130101 |
International
Class: |
C06B 25/20 20060101
C06B025/20; C06B 29/20 20060101 C06B029/20 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 25, 2013 |
DE |
10 2013 104 170.1 |
Claims
1. An electrically ignitable caseless propellant charge in the form
of a caseless propellant tablet or a tablet-like ignition charge,
comprising a mixture of at least one current-conductive material in
dissolved or dispersed form or powder form and additionally
graphite in powder form, together with nitrocellulose, with or
without addition of further additives, and compacted to form a
propellant tablet.
2. The propellant charge according to claim 1, wherein carbon is
used as current-conductive material.
3. The propellant charge according to claim 1, wherein it further
comprises one or more oxygen generators in a proportion by weight
of from 12 to 50% by weight.
4. The propellant charge according to claim 3, wherein as oxygen
generator there are provided zinc peroxide, potassium chlorate,
potassium perchlorate or mixtures of two or more thereof.
5. The propellant charge according to claim 1, wherein it further
comprises a catalytically active metal oxide, in a proportion of
from 0.6 to 6.3% by weight and/or iron (III) oxide in a proportion
of up to 1.3% by weight.
6. The propellant charge according to claim 1, wherein it further
comprises a fuel source, or a binder in the form of a thermoplastic
plastics material containing exclusively carbon, hydrogen and
oxygen atoms, or mixtures of the fuel source and the binder.
7. The propellant charge according to claim 1, obtainable in a
process in which a hydrocarbon that is liquid at room temperature a
solvent that is liquid at room temperature or a mixture of two or
more thereof is added and partially or fully removed by drying.
8. The propellant charge according to claim 1, comprising in the
mixture of all constituents used that are employed in the
production: an oxygen generator, especially zinc peroxide,
potassium chlorate, potassium perchlorate or a mixture of two or
more thereof, in a proportion of from 12 to 50, preferably from 50
to 38% by weight, especially of 28.486% by weight; a catalytically
active metal oxide, especially manganese (IV) oxide, in a
proportion of from 0.6 to 6.3, especially of 2.848% by weight; iron
(III) oxide in a proportion of from 0.000 to 1.3% by weight,
especially of 0.373% by weight; a fuel source, especially aluminium
powder, in a proportion of from 0.000 to 12.5% by weight;
especially of 3.731% by weight; carbon, especially alder buckthorn
charcoal and/or carbon fibres, in a proportion of from 2.4 to 12.5%
by weight, especially of 7.961% by weight; a binder in the form of
a thermoplastic plastics material containing exclusively carbon,
hydrogen and oxygen atoms, especially methacrylic and/or acrylic
granules, in a proportion of from 1.2 to 7.5% by weight, especially
of 3.731% by weight; nitrocellulose, especially having a nitrogen
content of from 10.7 to 12.5%, with solvent--the latter especially
in a proportion of from 10 to 50, for example 35% by weight, based
on the nitrocellulose component with solvent--especially ethanol,
in a proportion of from 18 to 50% by weight, especially of 30.725%
by weight; a hydrocarbon that is liquid at room temperature or a
hydrocarbon mixture that is liquid at room temperature, such as
isooctane in a proportion of from 1.2 to 15% by weight, for example
from 9 to 15 or from 1.2 to 6.3% by weight, especially of 3.483% by
weight; a further solvent, especially acetone, in a proportion of
from 3.7 to 37.4% by weight, preferably from 9 to 16% by weight,
especially of 13.683% by weight; graphite powder in a proportion of
from 1.2 to 24.9% by weight, especially of 4.975% by weight; and
optionally but especially a preferably hydrophobic or hydrophobised
silicic acid in a proportion of from 0.2 to 3% by weight.
9. A process for the production of a propellant charge according to
claim 1 in the form of a caseless propellant tablet, which process
is comprised of mixing together of at least one current-conductive
material in dissolved or dispersed form or in powder form and
graphite in powder form, together with nitrocellulose, with or
without addition of further additives, and subsequent compaction to
form a propellant tablet.
10. The process according to claim 9, wherein the
current-conductive material in dissolved or dispersed form or in
powder form is mixed with nitrocellulose with or without addition
of further additives, wherein granules of the obtainable mixture
are produced, and those granules are used as the obtainable
mixture, and graphite in powder form is added to such a largely dry
obtainable mixture and mixed therewith, and then the mixture is
compacted to form propellant tablets.
11. A method of using a conductive material in dissolved or
dispersed form or in powder form to produce the electrically
ignitable propellant charge, in accordance with the process
according to claim 9.
12. A method comprising using a propellant charge according to
claim 1 in a bolt-driving tool for installing bolts, as an
explosive charge in a warning shot device, as a gas-generating
element in airbags, for driving cutting devices, for driving
pressing devices, as a propellant charge in small calibre rifles
for sporting purposes, or for captive bolt devices for animal
slaughtering.
13. The propellant charge according to claim 2, wherein the carbon
is used as current-conductive material in a proportion by weight of
from 2.4 to 12.5% by weight.
14. The propellant charge according to claim 5, wherein the
catalytically active metal oxide is manganese (IV) oxide.
15. The propellant charge according to claim 6, comprising the fuel
source of magnesium, fine iron or aluminium.
16. The propellant charge according to claim 15, comprising the
fuel source in an amount of up to 12.5% by weight.
Description
TECHNICAL FIELD OF INVENTION
[0001] The invention relates to an electrically ignitable caseless
propellant charge (for example for bolt-driving tools or other
devices and purposes as described in detail below) in the form of a
caseless propellant tablet, or furthermore a tablet-like ignition
charge.
DISCUSSION OF RELATED ART
[0002] Offenlegungsschrift DE 2417967 describes
nitrocellulose-based propellant charges suitable for driving-in for
fastening purposes, which are provided in cases having two open
ends, at one end of which ignition can be effected by means of a
spark or a hot wire. Alternatively, ignition can be effected by
means of a current through a specially shaped current-conducting
case-like metal coating, as described in Auslegeschrift DE 1 300
845.
[0003] A disadvantage of such devices is the necessity for
relatively complicated cases.
[0004] On the other hand, U.S. Pat. No. 3,854,400 describes
caseless propellants having a porosity achieved by dissolving out a
binder (for example potassium nitrate or toluene), especially for
firearms, which can be ignited by means of additional ignition
charges. Further ingredients are nitrocellulose having a nitrogen
content of from 13.2 to 13.5% ("guncotton"), diphenylamine as
stabiliser, and further additives. Apparently they are mechanically
ignitable (for example by means of firing pins).
[0005] DE-OS 2 245 510 also describes propellant compositions for
caseless propellant charges as a power source for projectiles and
percussion tools. They comprise a mixture of nitrocellulose having
a high nitrogen content (from 13.2 to 13.4%) and nitrocellulose
having a low nitrogen content (for example from 11.6 to 11.8%) and
also potassium nitrate, which are formed into grains, then
converted into porous form by dissolving out the potassium nitrate
and extruded in the form of a 1.4 mm thick "cord" which is then cut
into 0.32 mm thick discs. The discs are then tumbled in a pan with
fine graphite in order to provide a coating to improve flow
properties and introduction into a mould, and the particles are
then compacted in a mould to form cylindrical propellant charges.
In this case additional priming compositions are always introduced
into an indentation. Electrical ignition is not mentioned.
[0006] DE-OS 1 906 573 finally relates to caseless explosive
charges which can be ignited by means of power sources such as
torch batteries or capacitor discharge circuits. For ignition,
single-strand or multi-strand wires or graphite rods are introduced
into the composition.
[0007] Known tablets or propellant charges of similar form
accordingly have relatively complex structures.
[0008] In particular, their structure is relatively elaborate
insofar as current-conducting wires or rods need to pass through or
surround the ignitable propellant material in order to make
electrical ignition possible.
[0009] DE 37 07 694 C2 describes electrically primable priming
charges for caseless ammunition and propellant cartridges, which
comprise inter alia nitrocellulose having a nitrogen content of
13.5%, zinc peroxide and carbon fibres. They are used for priming
the actual propellant charges. DE 33 46 739 also describes priming
charges (primary explosive) to which in this case there is added
from 0.8 to 2.0% by weight furnace black or lamp black to increase
the conductivity. US 2003/0034103 describes ignition means for
propellant powders, which can be used as coatings for such
powders.
SUMMARY OF THE INVENTION
[0010] Against this background, the problem of the invention is to
provide simplified propellant charges which can be ignited by means
of power sources, without the need for a priming charge.
[0011] It has now been found that it is possible to provide
caseless electrically ignitable propellant charges (especially in
tablet form) which comprise conductive material in finely divided
form in their matrix.
[0012] In a first embodiment, the invention therefore relates to an
electrically ignitable caseless propellant charge (provided without
an additional ignition charge or current-conductive wires or rods)
in the form of a caseless propellant tablet (compact),
characterised in that it is obtainable by mixing together of at
least one current-conductive material in dissolved or dispersed
form or powder form (apart from, that is to say in addition to,
graphite) and graphite in powder form, together with
nitrocellulose, with or without addition of further additives, and
subsequent compaction to form a propellant tablet, or preferably by
one of the processes described below.
[0013] The dissolved, dispersed or powder form of the
current-conductive material used (unlike implementation in the form
of wires or rods or ignition from an outer side) brings about the
"finely divided form" and allows rapid and homogeneous
ignition.
[0014] "Powder form" always includes powder having elongate
particles (such as carbon chips or carbon fibres) and/or particles
of a rather roundish (approximately spherical) shape.
[0015] For further improvement of current conductivity, carbon
fibres can have been added or they can be added in the following
process.
[0016] In a further embodiment, the invention relates to a process
for the production of a propellant charge mentioned hereinabove or
hereinbelow in the form of a caseless propellant tablet, which
process is characterised by mixing together of at least one
current-conductive material in dissolved or dispersed form or in
powder form, apart from graphite, and graphite in powder form,
together with nitrocellulose, with or without addition of further
additives, and subsequent compaction to form a propellant
tablet.
[0017] A preferred embodiment of the production process relates to
a process as mentioned above, which is characterised in that a
current-conductive material in dissolved or dispersed form or in
powder form, apart from graphite, is mixed with nitrocellulose,
with or without addition of further additives, (wherein in a
special embodiment of the invention granules of the obtainable
mixture are produced, preferably by grinding, and those granules
are used as the obtainable mixture), and graphite in powder form is
added to a largely dry obtainable mixture (especially having not
more than 15% by weight, for example having 6-12 or having 8-10% by
weight residual moisture) (if necessary obtained or obtainable by a
drying step), and then the mixture is compacted to form propellant
tablets according to the invention. A possible advantage of such a
process is that the at least partly soluble materials (such as
nitrocellulose and acrylate granules) are able to penetrate around
and into the granules like a paint, which can bring about a
reduction in the hydrophilicity and thus contribute to the storage
stability and insensitivity to moisture of the propellant
charges.
[0018] Such processes also allow simple industrial production of
propellant charges according to the invention. Depending upon the
production, the propellant charges according to the invention that
are obtainable have a largely homogeneous structure in the sense of
a solid dispersion (solid-solid mixture); in simple terms, in the
preferred structure obtainable in accordance with the preferred
process the granules, which may be deformed after the pressing, and
optionally further particulate constituents are arranged as a
discontinuous phase in a kind of three-dimensional lattice
structure having a high graphite content. The graphite can
therefore bind the granules practically in the form of a
three-dimensional lattice, so that even with only a small
proportion of graphite it is possible to achieve sufficient
conductivity for the ignition current.
[0019] The invention relates also to the use of a conductive
material in dissolved or dispersed form or in powder form in the
production of an electrically ignitable propellant charge.
[0020] The use takes place especially with implementation of the
steps of one of the production processes mentioned hereinabove and
hereinbelow.
[0021] A further embodiment of the invention relates also to the
use of a propellant charge according to the invention described
hereinabove and hereinbelow in a bolt-driving tool for installing
bolts, as an explosive charge in a warning shot device, as a
gas-generating element in airbags, for driving cutting devices or
as a propellant charge in small calibre rifles for sporting
purposes.
[0022] In addition to the fact that no awkward-to-install
current-conductive components, such as metal wires or rods, for
example made of graphite or metal, are required for ignition and
for that reason alone machine-based production is facilitated, the
caseless propellant charges according to the invention also have
further advantages of caseless propellant charges, for example
scope for any desired shaping, for example cylindrical, ovoid or
spherical; no polarity (no difference between a "front" and "rear",
as is the case with cartridges having ignition charges and/or
cases), ease of handling, for example even without "cartridge
belts" or the like; low weight and low space requirement. In
particular, they also allow ignition without special electrical
terminals or contacts provided in the propellant charge.
[0023] The propellant charges according to the invention are
suitable for use especially for bolt-driving tools, but also for
warning shot devices (for example for scaring away birds in
fruit-growing areas), as gas-generating elements in airbags, for
driving cutting devices such as bolt cutters or for cutting
tensioning devices in shipping, but they also come into
consideration, for example, as propellant charges in small calibre
rifles for sporting purposes, for example in the biathlon, or for
captive bolt devices for animal slaughtering.
[0024] The energy released for the mentioned purposes can
advantageously be in the range from 10 to 1200 Joule per propellant
charge, for example in the range from 50 to 1000 Joule, for example
between 50 and 700 Joule, for example between 150 and 400 Joule.
The measurement can be determined, for example by means of a
photoelectric barrier, from the mass and the speed of a shot.
[0025] Surprisingly, the propellant charges according to the
invention are water-proof and, for example, are very dimensionally
stable even under sub-tropical conditions (50.degree. C./75 to 80%
relative humidity)--in use they can also briefly fall into a
puddle, for example, and nevertheless be fully ignitable.
[0026] In comparison with propellant charges that have conventional
cases and are mechanically ignitable by impact by means of primers,
the propellant charges according to the invention additionally have
the advantage that they can be supplied directly to the device in
question (for example by means of a tube) in the form of a loose
product without retaining bands or the like. It is thus possible to
achieve, for example, reductions in volume down to an order of
magnitude of a tenth and reductions in weight down to an order of
magnitude of a fifth of the values for conventional propellant
charges (especially those having cases and/or ignition
charges).
[0027] Furthermore, the propellant charges according to the
invention have the advantage that they combust without residue--no
residual items, such as, for example, cases, wires or rods or a
plurality thereof, are left behind. The person skilled in the art
can easily determine the amounts of materials and additives it is
necessary to use for residue-free combustion (on the basis of
stoichiometric considerations and simple tests).
[0028] In addition, the shape of the propellant charges according
to the invention can be configured as desired, for example in a
spherical shape, a conical shape, in the form of polygonal bodies
or, especially, in a cylindrical shape, it being possible in
special embodiments also to provide a central through-hole, which
can be made, for example, by pressing tools suitably provided with
a spike.
[0029] An igniter (for example a primer, priming charge) is not
required and therefore preferably not provided--the propellant
charges according to the invention are therefore scalable as
desired; there is no necessity to distinguish between "front" and
"rear" (for example with an igniter in the "rear" region) and it is
unnecessary to provide indentations or the like for receiving
igniters.
[0030] Finally, the propellant charges according to the invention
also allow the exclusive use of cellulose nitrate
("nitrocellulose") freely available commercially, as is used, for
example, in paint bases. The nitrogen content (% by weight, based
on the nitrocellulose itself) of such nitrocellulose is here
approximately in the range from 10.7 to 12.5%, for example from
11.8 to 12.3%--unlike guncotton, where it is in the range from 13.2
to 13.5%.
[0031] Hereinbelow, unless otherwise indicated or apparent,
percentages by weight are based on the total weight of all
constituents of a mixture for the production of a propellant charge
according to the invention mixed together prior to drying and
compaction steps.
[0032] Preferably the nitrocellulose used for production in
accordance with the invention has been stabilised, for example with
a solvent such as a lower alcohol, for example ethanol or
isopropanol, it being possible for further stabilisers, such as
plasticisers, to have been added, such as epoxidised soybean oil or
acetyl tributyl citrate. Walsroder.TM. nitrocellulose E 330 ethanol
(Dow Chemical Co.) is an example of a preferred nitrocellulose.
Based on the nitrocellulose component itself, the proportion of
solvent and/or stabiliser can be in total from 10 to 50% by weight,
for example approximately from 30 to 40% by weight, for example 35%
by weight.
[0033] The proportion of nitrocellulose (optionally stabilised,
that is to say, for example, with solvent) in a propellant charge
according to the invention is, for example, advantageously in the
range from 18 (for example 18.695) to 50 (for example 49.757) % by
weight, especially from 27 to 35% by weight, including any solvent
present as mentioned. The nitrocellulose serves as propellant and
fuel and can furthermore act as water-resistant binder. For
example, the proportion of (optionally stabilised) nitrocellulose
is from 27.652 to 33.797 or from 27 to 35% by weight.
[0034] As current-conductive material, apart from graphite, in the
embodiments of the invention there come into consideration
especially carbon, preferably a wood charcoal (such as barbecue
charcoal), such as hazel, linden wood, beech, alder or vine
charcoal, carbon fibre chips (obtainable, for example, from R&G
Faserverbundwerkstoffe GmbH, Waldenbuch, Germany) or medical
charcoal (less preferred activated charcoal) or especially a rather
hydrophobic charcoal (having, for example, high conductivity and
low hygroscopicity) such as alder buckthorn charcoal (which tends
to be rather greasy), which is especially preferred, or carbon
chips. The charcoal used is preferably finely pulverised, for
example homogenised by means of a ball mill (tumbled) (ball mill
FP-2012, the steel balls supplied therewith were used, 9.5 or 16
mm); Feuerwerksparadies Wennesheimer, Tuttlingen, Germany). The
current-conductive material or the carbon is/has been added
advantageously in a proportion of from 2.4 (for example 2.487) to
12.5 (for example to 12.439) % by weight, or, for example, in a
proportion of from 3 to 6% by weight. The carbon serves inter alia
as fuel source and as current conductor. For example, the
current-conductive material can be provided in a proportion of from
7.164 to 8.757% by weight. Advantageously, alternatively or
preferably in addition it is possible to add a fibrous conductive
material, for example carbon fibres. In that case the proportion of
charcoal and/or fibrous material is preferably in the range from 3
to 12, especially from 3.5 to 6% by weight.
[0035] The graphite used in the embodiments of the invention can
perform several functions: firstly it can increase the electrical
conductivity inside the propellant charges according to the
invention and thus also play a part as current-conductive material
in the electrical ignition; furthermore it can contribute to a
smooth surface (also having a shiny metallic appearance) and can
increase the compressive strength, and finally it can also act as a
lubricant which facilitates the production of the propellant
charges according to the invention and their handling (insertion
etc.). It is/has been added advantageously in a proportion of from
1.2 (for example 1.243) to 24.9 (for example to 24.878) % by
weight. For example it can be provided in a proportion of from 2 to
6% by weight, for example from 2.4 to 3.1 or from 4.477 to 5.472%
by weight.
[0036] As further additives, especially the following come into
consideration:
[0037] One or more oxygen generators such as especially zinc
peroxide or potassium chlorate or potassium perchlorate or mixtures
of two (especially the two perchlorates or a perchlorate with zinc
peroxide) or all thereof can serve to supply oxygen for the
combustion (which allows the use of nitrocellulose having a lower
nitrogen content than guncotton) and are present in total
advantageously in a proportion of from 12 (for example 12.439) to
50 (for example to 49.757) % by weight. For example, the oxygen
generator or the mixture of oxygen generators can be provided in a
proportion of from 25.190 to 31.334% by weight or advantageously
from 25 to 38% by weight, for example from 30 to 38% by weight.
[0038] A catalytically active metal oxide, such as manganese (IV)
oxide (for example >90% precipitated, active; CAS No. 1313-13-9,
EC No. 215-202-6), can bring about lowering of the ignition
temperature, for example from about 550.degree. C. to about
150.degree. C. It can be/have been added advantageously in a
proportion of from 0.6 (for example 0.621) to 6.3 (for example to
6.291) % by weight. For example, the catalytically active metal
oxide can be provided in a proportion of from 1.3 to 3.2% by
weight, for example from 1.3 to 1.8% by weight or from 2.563 to
3.132% by weight.
[0039] Iron (III) oxide (for example CAS No. 1309-37-1/EC No.
215-168-2; for example content >97%) can support the combustion
and increase the combustion temperature) is/has been added
advantageously in a proportion of from 0.000 to 1.3 (for example to
1.243) % by weight and can serve to reduce harmful substances. For
example, the iron (III) oxide can be provided in a proportion of
from 0.335 to 0.410% by weight. It can also be absent however.
[0040] A semi-metallic (such as silicon) or metallic fuel source
such as magnesium, fine iron or especially aluminium (preferably
having a particle size of 160 .mu.m or less), titanium (for example
having a particle size of 40 .mu.m), or zirconium, or a mixture of
two or more thereof (supports the combustion and increases the
combustion temperature and can likewise be provided as further
current-conductive material apart from graphite) can be/have been
added in an amount of from 0.000 to 12.5 (for example to 12.439) %
by weight. For example, the fuel source can be provided in a
proportion of from 3.357 to 4.104% by weight. It can also be absent
however.
[0041] A binder (which also increases the long-term stability) in
the form of a thermoplastic plastics material containing
exclusively carbon, hydrogen and oxygen atoms is preferably an
acrylate or/or methacrylate, particle size about 200 to 400 .mu.m,
preferably of rather low molecular weight, which surprisingly can
serve to reduce any harmful substances (such as nitrous gases) that
are formed. It is/has been added advantageously in a proportion of
from 1.2 (for example 1.243) to 7.5 (for example to 7.463) % by
weight. For example, the binder can be provided in a proportion of
from 1.5 to 4.2% by weight, for example from 1.5 to 2.0% by weight
or from 3.357 to 4.104% by weight.
[0042] A hydrocarbon that is liquid at room temperature, such as,
for example, pentane and/or isooctane, or a corresponding
hydrocarbon mixture (such as petrol, for example automotive petrol
or petrol-based cleaner) can be/have been added advantageously in a
range from 1.2 (for example 1.243) to 15% by weight, for example
from 9 to 15% by weight or from 1.2 to 6.3 (for example to 6.219) %
by weight, during mixing of the composition of a propellant charge
according to the invention and, for example, prevents the
production tools from sticking. The proportion can be, for example,
from 9 to 15 or from 3.134 to 3.831% by weight. It can be
substantially or entirely removed or evaporated on drying.
[0043] A solvent for (especially for dissolving the fibre structure
of) nitrocellulose and the binder in the form of a thermoplastic
plastics material containing exclusively carbon, hydrogen and
oxygen atoms, such as acetone, methyl ethyl ketone or a different
ketone that is liquid at room temperature or an ester such as ethyl
acetate, or mixtures of two or more thereof, can be/have been added
in the production of a mixture for a propellant charge according to
the invention in a proportion of from 3.7 (for example 3.731) to
37.4 (for example to 37.718) % by weight. The proportion can be,
for example, from 9 to 16% by weight or from 12.314 to 15.051% by
weight. Such a solvent can be substantially or entirely removed or
evaporated on drying.
[0044] There can advantageously be added as further additive a
(preferably hydrophobic or hydrophobised)--for example pyro-genic
or precipitated--silicic acid (optionally with contained silicates,
such as aluminium and/or calcium silicates), such as, for example,
SIPERNAT.RTM. D10 from Evonik Industries AG, Hanau, Germany. The
proportion can be, for example, from 0.2 to 3% by weight, for
example from 0.3 to 1% by weight. This can give rise to a number of
advantages, such as, for example, increased storage stability on
account of the hydrophobicity, neutralisation of nitrous acids
formed on burning off a propellant charge according to the
invention in respect of the pH value, improved flow behaviour and
improved compressibility in the production process and/or further
improved burn-off behaviour of the propellant charges.
[0045] The process according to the invention for the production of
a propellant charge according to the invention, as described above,
can be carried out especially advantageously as follows, which
allows especially simple industrial production (also mentioned in
the Examples which follow):
[0046] The individual substances, apart from the graphite powder,
are weighed out, including the nitrocellulose (for example having a
content of 35% ethanol), and mixed together without addition of
solvent. The liquid substances (solvent and
hydrocarbon/-hydrocarbon mixture) are added and the resulting
dispersion or solution is mixed. This is followed by drying, for
safety reasons advantageously to a residual moisture content of
from 5 to 15% by weight, for example from 8 to 10% by weight,
residual moisture. The mixture is ground to form granules. Graphite
powder is then added and mixed therewith. The granules so
obtainable are ready for compaction and are compacted to form
tablets in a tabletting machine and dried (for example for 24 hours
at 60.degree. C.). The finished propellant charges according to the
invention are obtained.
[0047] In an embodiment of the invention, the propellant charge
according to the invention can have a (for example central) hole
which can pass all the way through and, for example, can be made by
a corresponding spike in the pressing tool during pressing.
[0048] An important embodiment of the invention relates to the
combination of nitrocellulose, carbon, graphite and acrylic
granules, preferably also carbon fibres and silicic acid as
constituents for the production of a propellant charge according to
the invention or obtainable propellant charges.
[0049] The Examples which follow serve to illustrate the invention
but do not limit the scope thereof.
[0050] FIG. 1 shows diagrammatically and in greatly simplified form
a portion of a tabletting device in cross-section and the pressing
operation during tabletting by means of a pressing die.
EXAMPLE 1
Propellant Charge According to the Invention in the Form of a
Cylindrical Tablet
TABLE-US-00001 [0051] Substance Weight (g) Weight (%) Potassium
chlorate/- 22.900 28.486 potassium chlorate mixture, in each case
50:50 g/g) Manganese(IV) oxide 2.290 2.848 Iron(III) oxide 0.300
0.373 Aluminium powder 3.000 3.731 particle size .ltoreq.160 .mu.m
Alder buckthorn charcoal 6.400 7.961 (particle size primarily in
the range from 0.02 to 0.05 mm) Acrylic granules.sup.1 3.000 3.731
particle size 200-400 .mu.m Nitrocellulose E 330.sup.2 24.700
30.725 with 35% by weight ethanol Isooctane 2.800 3.483 Acetone
11.000 13.683 Graphite powder (particle 4.000 4.975 size
predominantly in the range 0.05 to 1 mm) Total: 80.390 99.996
.sup.1ELVACITE .RTM. 2008 (Lucite International Inc., Cordova, TN,
USA) (a low molecular weight methyl methacrylate) .sup.2Walsroder
.TM. nitrocellulose E 330 ethanol (Dow Chemical Co.)
[0052] The particle size data relate to the result of optical
microscopic measurement of the particle size with a stage
micrometer and an ocular micrometer.
[0053] The individual substances, apart from the graphite powder,
are weighed out, including the nitrocellulose having a content of
35% ethanol, and mixed together without addition of solvent. The
liquid substances (acetone and isooctane) are added and the
resulting dispersion or solution is mixed. This is followed by
drying, for safety reasons to a residual moisture content of from 8
to 10% by weight residual moisture (which is also advantageous from
the safety aspect). The mixture is ground to form granules.
Graphite powder is then added. The granules provided with graphite
so obtainable are ready for compaction and are compacted to form
cylindrical tablets in a tabletting machine (for example FETTE
PERFECTA 1000, FETTE COMPACTING GmbH, Schwarzenbek, Germany) and
dried for 24 hours at 60.degree. C.
[0054] FIG. 1 shows a rough diagram of a portion of a mould 1 of
such a tabletting machine. On the left-hand side the granules 2 are
in the as yet uncompressed state inside a mould cavity 3. On the
right-hand side the pressing operation by means of the upper die 4
is shown in simplified form--here already at the stage of maximum
compression. The granules 2 have in this instance been compacted to
form a propellant tablet 5 (in this case, for example,
cylindrical). This comprises the electrically ignitable propellant
mixture with electrically conductive contents as described
hereinabove and hereinbelow.
EXAMPLE 2
Ignition of a Propellant Charge According to the Invention
[0055] In the case of a tablet 6.times.6 mm, the energy released
after ignition with 100 to 110 volts was about 300 to 350 J.
EXAMPLE 3
Climatised Storage Tests with Propellant Tablets According to the
Invention
[0056] Propellant tablets according to the invention were subjected
to dry storage at 20.degree. C. and 50% relative humidity until the
weight was constant. They could be ignited properly with an
ignition voltage of 100-110 volts.
[0057] The following water absorption is observed with a propellant
charge from Example 1 at the temperatures and relative humidities
indicated:
TABLE-US-00002 Days Water since Weight Relative absorption start of
Time of (g) Temperature humidity Tablets (% by storage day 5 items
.degree. C. (%) O mm X weight) 0 10:00 1.3420 47.7 86.70 6.00 0 3
10:00 1.3565 49.5 87.00 6.00 1.0847 4 10:07 13565 49.3 87.00 6.02
1.0847 4 items 1.0791 5 09:50 4 items 49.4 87.10 6.02 1.4831 1.0834
6 10:20 4 items 49.2 86.60 6.03 1.3349 1.0818 7 09.57 4 items 49.1
86.90 6.03 1.2515 1.0809
[0058] The propellant tablets are therefore stable towards even
elevated humidity and can be stored even at sub-tropical
humidities.
EXAMPLE 4
Propellant Charge Containing Carbon Fibres and Silicic Acid
[0059] Propellant charges having the following composition are
produced analogously to Example 1:
TABLE-US-00003 Substance Weight (g) Weight (%) Potassium chlorate
36.0 15.378 Manganese(IV) oxide 3.6 1.538 Carbon fibres (fibre
length 2.6 1.111 average 0.25 to 0.35 mm R&G
Faserverbundwerkstoffe GmbH, Waldenbuch, Germany)) Alder buckthorn
charcoal 8.0 3.417 (particle size primarily in the range from 0.02
to 0.05 mm) Acrylic granules.sup.1 particle 4.0 1.709 size 200-400
.mu.m Zinc peroxide (50-60%) 43.0 18.367 Sipernat D10.sup.2 1.5
0.641 Nitrocellulose E 330.sup.2 with 73.0 31.118 35% by weight
ethanol Isooctane 28.0 11.960 Acetone 28.0 11.960 Graphite powder
(particle 6.4 2.734 size predominantly in the range 0.05 to 1 mm)
Total: 234.1 (100)
[0060] The invention relates also to the subject matter of the
invention mentioned in the claims and in the abstract, which is
incorporated herein by reference.
* * * * *