U.S. patent application number 11/055455 was filed with the patent office on 2010-02-11 for lead-free nontoxic explosive mix.
Invention is credited to George C. Mei, James W. Pickett.
Application Number | 20100032063 11/055455 |
Document ID | / |
Family ID | 32659511 |
Filed Date | 2010-02-11 |
United States Patent
Application |
20100032063 |
Kind Code |
A1 |
Mei; George C. ; et
al. |
February 11, 2010 |
Lead-free nontoxic explosive mix
Abstract
The present invention is directed to a lead-free, nontoxic
pyrotechnic composition, comprising: 30-80 wt % of bismuth
subnitrate; and 10-50 wt % of a fuel, wherein all weight percents
are based on the total weight of the composition. The present
invention is also directed to a lead-free, nontoxic priming
composition, comprising: 20-80 wt % of the above nontoxic
pyrotechnic composition; 20-50 wt % of an initiator explosive; and
2-10 wt % of a sensitizer, wherein all weight percents are based on
the total weight of the composition.
Inventors: |
Mei; George C.; (Creve
Coeur, MO) ; Pickett; James W.; (Gillespie,
IL) |
Correspondence
Address: |
HARNESS, DICKEY, & PIERCE, P.L.C
7700 Bonhomme, Suite 400
ST. LOUIS
MO
63105
US
|
Family ID: |
32659511 |
Appl. No.: |
11/055455 |
Filed: |
February 10, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10462555 |
Jun 16, 2003 |
6878221 |
|
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11055455 |
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60443790 |
Jan 30, 2003 |
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Current U.S.
Class: |
149/22 ; 149/41;
149/45 |
Current CPC
Class: |
C06C 7/00 20130101; C06B
33/04 20130101 |
Class at
Publication: |
149/22 ; 149/45;
149/41 |
International
Class: |
C06B 47/10 20060101
C06B047/10; C06B 31/00 20060101 C06B031/00; C06B 33/14 20060101
C06B033/14 |
Claims
1. A lead-free, nontoxic pyrotechnic composition, comprising:
approximately 60 wt % of bismuth subnitrate; and approximately 40
wt % of a fuel, wherein all weight percents are based on the total
weight of said composition, and wherein said composition is
substantially lead-free and substantially nontoxic.
2. (canceled)
3. The lead-free, nontoxic pyrotechnic composition of claim 1,
wherein said fuel is selected from the group consisting of
amorphous boron, aluminum powder, zirconium powder, titanium
powder, zinc powder, carbon, silicon, antimony sulfide, bismuth
sulfide, iron sulfide, zinc sulfide, calcium silicide, copper
silicide, and combinations thereof.
4. (canceled)
5. The lead-free, nontoxic pyrotechnic composition of claim 1,
further comprising a friction agent.
6. The lead-free, nontoxic pyrotechnic composition of claim 5,
wherein said friction agent is selected from the group consisting
of glass particles, silicon carbide, silicon, crystalline boron,
ceramics, and combinations thereof.
7. The lead-free, nontoxic pyrotechnic composition of claim 5,
wherein said friction agent comprises from about 0 to about 50 wt %
of said composition.
8. The lead-free, nontoxic pyrotechnic composition of claim 1,
further comprising additional ingredients selected from the group
consisting of binders, PVA (polyvinylacetate), Karaya, Tragacanth,
Guar, Gum Arabic, and combinations thereof.
9.-24. (canceled)
Description
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/443,790 filed Jan. 30, 2003.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention is directed to explosive mixes, and
more particularly lead-free and non-toxic explosive mixes.
[0004] 2. Brief Description of the Related Art
[0005] Various lead-free priming mixtures for use in ammunition
have been disclosed over the years. For example, a nontoxic,
noncorrosive priming mix described in U.S. Pat. No. 4,675,059 is
one such composition. This priming composition contains
diazodinitrophenol, also known as dinol or DDNP, manganese dioxide,
tetrazene and glass. Another example of a nontoxic priming mixture
is disclosed in U.S. Pat. No. 4,963,201, issued to Bjerke et al.
This composition comprises dinol or potassium dinitrobenzofuroxan
as the primary explosive, tetrazene as a secondary explosive, a
nitrate ester fuel and strontium nitrate as the oxidizer. U.S. Pat.
No. 5,993,577 to Erickson et al. discloses a lead-free priming
composition made from diazodinitrophenol (DDNP), a low percentage
of tetrazene, and a high percentage of an abrasive such as ground
glass.
[0006] Many of the leadfree mixes based on dinol (DDNP), despite
being "leadless", still contain toxic heavy metals such as barium
and antimony. These are present in the fuels and oxidizers
traditionally used in priming mixtures. Other fuels and oxidizers
have also been employed, but many of them suffer from
hygroscopicity, inherent moisture retention, sensitivity to
moisture, unavailability, instability, and inherent processing
difficulties.
[0007] Bismuth compounds have been used in various medications and
personal care compositions. For example, U.S. Pat. No. 6,426,085 to
Athanikar discloses use of bismuth-containing compounds in topical
oral dosage forms for the treatment of halitosis. U.S. Pat. No.
6,379,651 to Athanikar discloses treatments with bismuth compounds,
other antibacterial compounds, and/or antibiotics in oral-topical
and peroral dosage forms to eradicate H. pylori order to improve
the ulcer cure rate and prevent ulcer relapse. U.S. Pat. No.
6,372,784 to Athanikar discloses a method for treatment of corneal
and dermal wounds by administering bismuth compounds in topical
dosage forms. In addition, bismuth has been demonstrated to be an
accepted non-toxic material used in non-toxic shot for waterfowl
hunting.
[0008] Bismuth subnitrate (also known as bismuth nitrate basic,)
has been disclosed for use as an antacid, and in compositions for
regulating wrinkles or atrophy in mammalian skin (See for example
U.S. Pat. Nos. 5,883,085; 5,837,697; 5,811,413; 5,795,879; and
5,780,458).
[0009] U.S. Pat. No. 6,478,903 to John, Jr. discloses a non-toxic
primer mix including both bismuth sulfide and potassium nitrate as
the pyrotechnic portion of the primer. However, bismuth subnitrate
is not disclosed.
[0010] What is needed in the art is a lead-free, non-toxic priming
composition that reduces or eliminates toxic heavy metals such as
antimony and barium, yet is economical, easy to produce, and is
free from the above-mentioned problems of hygroscopicity, inherent
moisture retention, and moisture sensitivity. The present invention
is believed to be an answer to that need.
SUMMARY OF THE INVENTION
[0011] In one aspect, the present invention is directed to a
lead-free, nontoxic pyrotechnic composition, comprising: 30-80 wt %
of bismuth subnitrate; and 10-50 wt % of a fuel, wherein all weight
percents are based on the total weight of the composition.
[0012] In another aspect, the present invention is directed to a
lead-free, nontoxic priming composition, comprising: 20-80 wt % of
the above pyrotechnic composition; 20-50 wt % of an initiator
explosive; and 2-10 wt % of a sensitizer, wherein all weight
percents are based on the total weight of the composition.
[0013] In another aspect, the present invention is directed to a
lead-free, nontoxic priming composition, comprising 25-35 w % of
bismuth subnitrate; 5-10 wt % of fuel; 20-50 wt % of an initiator
explosive; and 2-10 wt % of a sensitizer, wherein all weight
percents are based on the total weight of the composition.
[0014] These and other aspects will become apparent upon reading
the following detailed description of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] It has now been unexpectedly discovered by the inventors
that the problem of toxic heavy metal content and moisture
sensitivity in explosive mixes may be addressed by incorporation of
bismuth subnitrate as an oxidizer in these compositions. Bismuth is
a useful alternative to toxic heavy metals, such as barium or
antimony, found in fuels and oxidizers in the prior art explosive
mixtures. In addition, bismuth subnitrate is insoluble in water, a
medium critical to safe desensitization of explosive mixes during
processing.
[0016] As indicated above, in one embodiment, the present invention
is directed to a lead-free, nontoxic pyrotechnic composition,
comprising about 30-80 wt % of bismuth subnitrate; and about 10-50
wt % of a fuel, wherein all weight percents are based on the total
weight of the composition. In another embodiment, the present
invention is directed to a lead-free, nontoxic priming composition,
comprising about 20-80 wt % of the above pyrotechnic composition;
about 20-50 wt % of an initiator explosive; and about 2-10 wt % of
a sensitizer, wherein all weight percents are based on the total
weight of the composition. Each of these components are discussed
in more detail below.
[0017] Bismuth subnitrate is a basic salt, the composition of which
generally varies with the conditions of its preparation. Bismuth
subnitrate is generally 70 to 74% bismuth or 79 to 82% BiO.sub.3,
and is generally prepared by partial hydrolysis of
Bi(NO.sub.3).sub.3. In the pyrotechnic composition of the present
invention, bismuth subnitrate comprises about 30-80 wt % of the
composition, and more preferably approximately 60 wt % of the
composition. In the priming composition of the present invention,
bismuth subnitrate preferably comprises about 10-40 wt % of the
composition, and more preferably approximately 20 wt % of the
composition.
[0018] The fuel component of the invention may be any fuel useful
in the preparation of explosives or priming mixes. Examples of
useful fuels include amorphous boron, metal powders, such as
aluminum powder, zirconium powder, titanium powder, zinc powder,
and the like; semiconductors such as carbon, silicon, and the like;
metal sulfides, such as antimony sulfide, bismuth sulfide, iron
sulfide, zinc sulfide, and the like; metal suicides, such as
calcium silicide, copper silicide, as well as combinations of all
of the above. Additional fuels and combinations thereof may also be
used in the present invention. In the pyrotechnic composition of
the invention, the fuel component ranges from about 10 to about 50
wt %, and more preferably about 40 wt %. In the priming composition
of the invention, the fuel component preferably comprises from
about 2 to about 30 wt %, and more preferably about 5 wt %.
[0019] In both embodiments, a particularly preferred fuel is boron,
and particularly amorphous boron. Boron, may have an additional
advantage in that it produces boric oxide as its combustion
product. Boric oxide combines rapidly with moisture, also produced
in the combustion process, to make boric acid. Boric acid is
environmentally harmless and nontoxic. In addition, boric acid can
act as a lubricant. Thus the composition of the invention may be a
self lubricating primer composition which may tend to inhibit
ammunition component and barrel wear.
[0020] In a preferred embodiment of the priming composition, the
final concentration of fuel ranges from about 5 to about 10 wt %,
and is preferably about 7 wt %, based on the total weight of the
composition. The final concentration of bismuth subnitrate in this
preferred embodiment ranges from about 25 to about 35 wt %, and is
preferably about 28 wt %, based on the total weight of the
composition.
[0021] Both the explosive embodiment and priming embodiment of the
present invention may also include an optional friction agent.
Friction agents useful in both embodiments of the present invention
include glass particles, silicon carbide, silicon, crystalline
boron, ceramics, and combinations thereof, although other friction
agents and abrasives common and known in the art may also be used.
In general, both embodiments of the invention may incorporate the
optional friction agent in an amount ranging from about 0 to about
50 wt % of the respective compositions. Although the friction agent
may be of any particle size, preferred particle sizes range from
about 50 to about 150 microns.
[0022] The priming composition of the invention includes additional
components such as initiator explosives, sensitizers, "fast-fuels",
and the like.
[0023] Useful initiator explosives include dinol,
dinitrodihydroxydiazobenzene salt (diazinate), dinitrobenzofuroxan
salts, perchlorate or nitrate salt of metal complexes of ammonium,
amine, or hydrazine. An example is
2-(5-cyanotetrazolato)pentaaminecobalt (III) perchlorate (CP),
various diazo, triazole, and tetrazaole compounds, and combinations
thereof. Preferred amounts of initiator explosive in the priming
composition of the invention range from about 20 to about 50 wt %,
and preferably approximately 35 wt %.
[0024] A useful sensitizers is tetrazene. Preferred amounts of
sensitizer in the priming composition of the invention range from
about 2 to about 10 wt %, and preferably approximately 5 wt %.
[0025] A "fast-fuel" may also be optionally included in the priming
composition of the invention. Useful fast-fuels include potassium
styphnate, nitrate esters such as nitrocellulose-based propellants,
or PETN, and combinations thereof. Preferred amounts of fast-fuel
generally range from about 0 to about 30 wt %, and preferably
approximately 20 wt %.
[0026] Additional ingredients such as binders, PVA
(polyvinylacetate), Karaya, Tragacanth, Guar, Gum Arabic, etc., and
combinations thereof, may also be included in both the pyrotechnic
composition or the priming composition of the invention.
[0027] Both boron and bismuth-subnitrate are formed in micron to
sub-micron sizes in manufacturing processes. Both are readily
available commercially, offering more cost efficient utilization.
The boronjbismuth-subnitrate mixtures may approach the sensitivity
of the meta interstitial compounds (MICs), and such mixtures are
not plagued with the hazards of handling and the costs associated
with producing nano-size materials.
[0028] The composition of the present invention is easily
substituted for leaded priming mixtures, and can be processed using
conventional techniques. The mix of the present invention can be
used directly in Boxer type components without any modification.
This aspect of the present invention is particularly important
because shooters can reload ammunition with this type of primer
without having to buy primed cases. Finally, the mix of the
invention forms nontoxic products including boron oxides.
[0029] In one embodiment, the composition may be manufactured by
mixing and kneading the said ingredients in a mixer similar to
those used for food processing. The resulting dough (containing 10
to 30% moisture) is then rubbed against a leaf honeycombed with a
matrix of holes of fixed volume. After the holes are filled and
leveled, the pellets so formed are knocked out and transferred into
primer cups where a foil is then added and the mix consolidated.
Finally, to finish the assembly, the cups are topped with anvils
that are preinstalled in battery cups. The finished primers then
proceed to be dried.
[0030] In use, the charge weight of the priming mix will vary
according to the loads being developed. Additionally, although the
mix is developed specifically for shotshell, various versions of
mix within the scope of the claims can be used also in center fire,
rim fire, or other similar type of applications, for example:
fuses, igniters, air bag initiators etc, even in electric or
current initiated devices. In a typical shotshell application, for
example, 1 oz loads, charge weight it should fall between 0.48 and
0.90 grains, and more preferably from 0.58 to 0.70 grains.
Appropriate charge weights for other applications mentioned above
are within the skill of the ordinary skilled practicioner.
EXAMPLES
Example 1
Preparation of a Pyrotechnic Mixture
[0031] To form a pyrotechnic mixture, appropriate amounts of each
of the ingredients is sieved through a 30 mesh screen and layered
on top of each other. The loose dry powders are then tumbled
together in a well-grounded container until a uniform mixture is
obtained. For safe processing, water or organic solvent can be
added to desensitize the mixture (up to approximately 30%). To
obtain a more intimate mixing for enhancing mix sensitivity, the
mixture can be subjected to sonication in liquid.
Example 2
Preparation of Priming Mixture I
[0032] To form a priming mixture, desired amounts of initiating
explosive, sensitizer, and fast fuel(s) are weighed wet for obvious
safety reasons. The mixture is de-watered to form a wet cake called
premix. The premix is then transferred to the bowl of a mixer, and
the dry ingredients including fuels, oxidizers, friction agents,
and binders are layered sequentially on top of the premix. Water is
added to adjust for the final moisture (up to approximately 30%).
Finally, the operator leaves the room and the mixing is done
remotely. When the mixing is complete, the mixture should have a
consistency of flour dough.
Example 3
Preparation of Priming Mixture II
[0033] Using the procedure outlined in Example 2, a priming mixture
was prepared having the following final concentrations:
TABLE-US-00001 Ingredient Amount (final wt %) Dinol 30 Tetrazene 5
Potassium Styphnate (monosubstituted) 15 Boron 7 Bismuth Subnitrate
28 Glass fines 15
[0034] The above mixture was formed into a shotshell primer using
conventional techniques, and tested as follows.
[0035] A primer held in a fixture is butted against a firing pin on
which a 2 oz steel ball is dropped from various heights. SAAMI
(Small Arms and Ammunition Manufacturers Institute) requirements
are no fire below a one inch height and all fire above 11 inches
drop height for small pistol primers. This test is an industry
production standard test. The heights cover a range from 0% fire to
100% fire. Then, through statistic means, the 50% fire height (H
bar) and spread (S) is calculated. When primers were dropped in
headed shells, the composition of Mixture II above gave H bar of
5.38'' and S of 1.09'', while control ("leaded") primer gave H bar
of 5.64'' and S of 1.04''. When primer was supported in a steel
die, Mixture II gave a H bar of 3.02'' and S of 0.81, well within
the typical range of a leaded counter part. As shown in the above
data, the shotshell primer made from this mix when tested in the
form of headed shells or by itself yielded sensitivity equal to
those of the regular leaded primer.
[0036] While the invention has been described above with reference
to specific embodiments thereof, it is apparent that many changes,
modifications, and variations can be made without departing from
the inventive concept disclosed herein. Accordingly, it is intended
to embrace all such changes, modifications, and variations that
fall within the spirit and broad scope of the appended claims. All
patent applications, patents, and other publications cited herein
are incorporated by reference in their entireties.
* * * * *