U.S. patent application number 10/986458 was filed with the patent office on 2005-10-13 for non-toxic primer powder composition for small caliber ammunition.
Invention is credited to Jung, Sung Mo, Lee, Hong Sik, Pak, Chang Ho, Son, Jong Woo.
Application Number | 20050224147 10/986458 |
Document ID | / |
Family ID | 35059342 |
Filed Date | 2005-10-13 |
United States Patent
Application |
20050224147 |
Kind Code |
A1 |
Jung, Sung Mo ; et
al. |
October 13, 2005 |
Non-toxic primer powder composition for small caliber
ammunition
Abstract
The present invention relates to a non-toxic primer powder
composition for small caliber ammunition characterized by
comprising potassium nitrate coated with shellac as an oxidizer,
and particularly characterized by comprising 25-40 wt % of an
initiating explosive, 10-30 wt % of nitrate ester as a fuel, 32-40
wt % of a shellac-coated potassium nitrate (KNO.sub.3) as an
oxidizer, 5-10 wt % of tetracene as a first sensitizer, 3-9 wt % of
a borosilicate powder as a second sensitizer and 0.1-0.2 wt % of a
chemical binder.
Inventors: |
Jung, Sung Mo; (Pohang-si,
KR) ; Lee, Hong Sik; (Gyeongju-si, KR) ; Son,
Jong Woo; (Gyeongju-si, KR) ; Pak, Chang Ho;
(Suwon-si, KR) |
Correspondence
Address: |
LOWE HAUPTMAN GILMAN AND BERNER, LLP
1700 DIAGONAL ROAD
SUITE 300 /310
ALEXANDRIA
VA
22314
US
|
Family ID: |
35059342 |
Appl. No.: |
10/986458 |
Filed: |
November 12, 2004 |
Current U.S.
Class: |
149/77 |
Current CPC
Class: |
C06B 45/32 20130101;
C06C 7/00 20130101 |
Class at
Publication: |
149/077 |
International
Class: |
C06B 035/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2004 |
KR |
10-2004-0021686 |
Claims
What is claimed is:
1. A primer powder composition for small caliber ammunition which
comprises an initiating explosive, a fuel, an oxidizer, a
sensitizer and a chemical binder, characterized by comprising a
shellac-coated potassium nitrate as the oxidizer.
2. The primer powder composition for small caliber ammunition
according to claim 1, wherein the shellac-coated potassium nitrate
has the weight ratio of shellac to potassium nitrate being
0.007:1.about.0.025:1.
3. The primer powder composition for small caliber ammunition
according to claim 1, wherein the composition consists of 25-40 wt
% of an initiating explosive, 10-30 wt % of nitrate ester as a
fuel, 32-40 wt % of a shellac-coated potassium nitrate as an
oxidizer, 5-10 wt % of tetracene as a first sensitizer, 3-9 wt % of
a borosilicate powder as a second sensitizer and 0.1-0.2 wt % of a
chemical binder.
4. The primer powder composition for small caliber ammunition
according to claim 1, wherein the initiating explosive is one or
more selected from the group consisting of a diazo compound
including diazodinitrophenol, a triazole compound, a tetrazole
compound and a nitrobenzene compound such as potassium
dinitrobenzofroxane and monopotassium styphnate.
5. The primer powder composition for small caliber ammunition
according to claim 1, wherein the chemical binder is a mixture of
arabian gum, tragacanth and gelatin mixed with a weight ratio of
9:5:1.
Description
TECHNICAL FIELD
[0001] The present invention relates to a non-toxic primer powder
composition for small caliber ammunition characterized by
comprising potassium nitrate coated with shellac as an oxidizer,
and particularly characterized by comprising an initiating
explosive, nitrate ester as a fuel, a shellac-coated potassium
nitrate (KNO.sub.3) as an oxidizer, tetracene as a first
sensitizer, a borosilicate powder as a second sensitizer and a
chemical binder.
BACKGROUND ART
[0002] A primer powder composition is generally comprised of an
initiating explosive, a fuel, an oxidizer, a sensitizer and a
chemical binder. Reviewing each function of said components, the
initiating explosive initiates detonation of the primer powder by
impact caused by a stroke of a hammer; the fuel generates flame by
which a propellant can be combusted, in which the combustion is
initiated by the detonation of the initiating explosive; the
oxidizer provides oxygen required for combustion of the fuel,
i.e..sub.2 serves as an oxygen provider; the sensitizer helps the
detonation of the initiating explosive so to respond to very subtle
impact; and the chemical binder conglomerates the components of the
primer powder composition hard so as to prevent the loss of said
components
[0003] The bullet firing is carried out by following mechanism:
when a hammer of a gun strokes the primer, an initiating explosive
is ignited and detonated, and then a propellant inside the bullet
is combusted by the explosive power of a fuel as the detonation
occurs, to fire the bullet.
[0004] Conventional primer powder compositions commonly make use of
lead styphnate as an initiating explosive, antimony sulfide as a
fuel, barium nitrate as an oxidizer. However, those conventional
compositions have problems of, when the primer powder composition
is detonated, generation of hazardous oxide-containing flying dust
such as lead oxide (PbO) due to oxidation of lead styphnate,
antimony oxide (Sb.sub.2O.sub.3) due to oxidation of antimony
sulfide, barium oxide (BaO) due to reduction of barium nitrate.
Such oxide-containing flying dust is a toxic material, which is
taken and accumulated in the human body, thus to disturb the human
body function, thereby being very harmful to a shooter,
particularly in indoor shooting ranges. The oxide-containing dust
also causes environmental hazards.
[0005] Regarding the toxic problem, there is a registered Korean
Patent concerning a non-toxic primer powder composition, however,
it has problems such that a lot of sparks are generated when
firing, thereby being dangerous, and a corrosive salt, potassium
chloride (KCl) is accumulated to the gun, thereby causing corrosion
in the gun.
[0006] U.S. Pat. No. 5,417,160 disclose a use of potassium nitrate
instead of barium nitrate, in order to prevent the generation of
such hazardous oxide compounds; however it has a problem such that
the sensitivity and performance of the primer is lowered, due to
hygroscopicity of potassium nitrate (water solubility of 31.6 g/100
ml, at 20.quadrature.), which is a property of absorbing moisture
in the air.
[0007] Another U.S. Pat. No. 6,620,267 disclose a technique of
coating potassium nitrate with an insoluble material,
nitrocellulose, in order to solve the problem of hygroscopicity of
potassium nitrate; however, it does not sufficiently overcome said
hygroscopicity problem of potassium nitrate and also has a risk of
explosion of nitrocellulose which can be caused by any impact or
abrasion, thereby having a serious problem in safety during
working.
[0008] In order to solve such problems, the present invention uses
a shellac resin that is an animal-originated natural resin, for
coating potassium nitrate with, instead of nitrocellulose so to
improve the lowered sensitivity and performance problems of a
primer due to hygroscopicity of the primer powder as well as
prevent explosion problem of conventional arts.
[0009] Therefore, the object of the invention is to improve
above-mentioned problems in conventional arts, specifically to
provide a non-toxic primer powder composition for a small caliber
ammunition which does not generate heavy metal oxides upon ignition
of the primer powder composition when bullet firing, so to protect
the shooter and environment from harmful heavy metal compounds, and
solve the problems in conventional non-toxic primer powder
including spark generation and accumulation of corrosive salt, and
to solve the problems caused by hygroscopicity of potassium
nitrate.
BRIEF DESCRIPTION OF THE DRAWING
[0010] FIG. 1 is a cross-sectional view of a typical primer of
small caliber ammunition
[0011] Symbols Used in FIG. 1
1 10: anvil 20: foiling paper 30: primer powder 40: Cup
DETAILED DESCRIPTION OF THE INVENTION
[0012] The primer powder composition for small caliber ammunition
of the present invention is characterized by comprising a
shellac-coated potassium nitrate as an oxidizer.
[0013] According to one preferred embodiment of the present
invention, provided is a primer powder composition for small
caliber ammunition which comprises 25-40 wt % of an initiating
explosive, 10-30 wt % of nitrate ester as a fuel, 32-40 wt % of a
shellac-coated potassium nitrate (KNO.sub.3) as an oxidizer, 5-1 wt
% of tetracene as a first sensitizer, 3-9 wt % of a borosilicate
powder as a second sensitizer and 0.1-0.2 wt % of a chemical
binder.
[0014] Based on above preferred embodiment, the present invention
is described further in detail, hereinafter.
[0015] Although lead styphnate, which generates lead oxide that is
hazardous compound to the human body by the following oxidation
reaction: 1 ( 2 C 6 H ( NO 2 ) 3 O 2 Pb + 11 2 O 2 -> 2 PbO + 12
CO 2 + 3 N 2 + H 2 O )
[0016] is used as an initiating explosive in many conventional
arts, diazodinitrophenol (DDNP) is preferably used as an initiating
explosive of the present invention, wherein DDNP which is sensitive
and relatively safer compared to conventional initiating explosive
comprising heavy metal, can by synthesized by conventional chemical
reagents and does not generate any harmful compounds to the human
body by its oxidation reaction,
((NO.sub.2).sub.2C.sub.6H.sub.2ON.sub.2+4O.sub.2.fwdarw.6CO.sub-
.2+2N.sub.2+H.sub.2O).
[0017] DDNP may be included in the primer powder composition of the
present invention, preferably with an amount of 25-40 wt %. When
being used less than 25 wt %, the explosive power will be not
sufficient enough, and when more than 40 wt %, the explosive power
will be so great to cause deterioration in performance of the
warhead.
[0018] Other than said DDNP, one or more initiating explosive
selected from the group consisting of a diazo compound, a triazole
compound, a tetrazole compound and a nitrobenzene compound such as
potassium dinitrobenzofroxane and monopotassium styphnate can be
used in the primer powder composition of the present invention.
[0019] Antimony sulfide which was used as a fuel in many
conventional arts, generates a hazardous antimony oxide
(Sb.sub.2O.sub.3) and sulfurous acid gas by the following
oxidization reaction: 2 ( Sb 2 O 3 + 9 2 O 2 -> Sb 2 O 3 + 3 SO
2 ) .
[0020] Therefore, in order to prevent generation of such hazardous
components, the present invention uses nitrate ester being free of
heavy metal, instead of such conventional fuel.
[0021] The nitrate ester is included in the primer powder
composition of the present invention, preferably with an amount of
10-30 wt %. When being used less than 10 wt %, flame of the primer
will not be sufficient enough to provide active combustion of a
propellant, and when more than 30 wt %, the flame will be so great
to cause abnormal combustion rate of the propellant, thereby having
a risk of generating an abnormal pressure.
[0022] As for said nitrate ester, any nitrate ester which is
produced by a general method well-known in this field of the art,
for example a spherical propellant (PMCWC844 manufactured by
Poongsan Corp.) with a particle size of 0.25-0.35 mm, comprising
10.5 wt % of nitroglycerin, 84 wt % of nitrocellulose, 4.5 wt % of
a retardant and 1 wt % of a stabilizer is preferably used.
[0023] Barium nitrate which was used as an oxidizer in many
conventional arts, generates a hazardous barium oxide (BaO) by the
following reducing reaction: 3 ( Ba ( NO 3 ) 2 -> BaO + N 2 + 5
2 O 2 ) .
[0024] Therefore, in order to prevent generation of such hazardous
components, the present invention uses potassium nitrate being free
of heavy metal and generating a salt with no corrosiveness as
follows: 4 ( 2 KNO 3 -> K 2 O + N 2 + 5 2 O 2 ) .
[0025] The potassium nitrate is coated with a shellac to be used in
the present invention, wherein the shellac is a animal-originated
natural resin which is obtained from an insect in tropical regions,
has relatively low melting point, heat-conductivity and coefficient
of expansion, and is durable to UV light, non-toxic and excellent
in moisture proof, thereby commonly being applied as a finishing
material in a coating process.
[0026] Since the conventional potassium nitrate is not suitable for
a component of a primer powder due to its great hygroscopicity, the
present invention has solved the problem by coating the potassium
nitrate with said shellac.
[0027] The weight ration of shellac and potassium nitrate is
preferably 0.007:1.about.0.025:1, when the ratio of shellac to
potassium nitrate is less than 0.007, moisture proofing will not be
sufficient enough, and when being more than 0.025, it will
disadvantageously affect the sensitivity.
[0028] The shellac-coated potassium nitrate particles may be
partially exposed to the moisture during a sieving process, however
the majority of the potassium nitrate particles are at least
partially or completely coated so to contribute to block moisture
present in the air. In particular, when using non-coated potassium
nitrate, the resulted primer will absorb moisture in the air, since
the solubility of the non-coated potassium nitrate is higher than
that of the coated potassium nitrate in a process of mixing primer
powder components, on working for mixing the primer explosive
powder components. Accordingly, the sensitivity of the primer may
be lowered so that the sensitivity of the primer could not satisfy
the standard level required for a primer, depending on the use
environment
[0029] The shellac-coated potassium nitrate is included in the
primer powder composition of the present invention, preferably with
an amount of 32-40 wt %, when being less than 32 wt %, the
explosive combustion properties becomes lower since the amount of
oxygen provided is not enough, and when more than 40%, other
components becomes relatively reduced so that generation of energy
for igniting a propellant is likely to reduced.
[0030] The present invention also preferably makes use of a
borosilicate powder as a second sensitizer, other than tetracene
that is conventionally used as a first sensitizer.
[0031] Each tetracene and borosilicate powder is included in the
primer powder composition of the present invention, preferably with
an amount of 5-10 wt % and 3-9 wt %, respectively. When tetracene
is used less than 5 wt %, the impact sensitivity of the primer
could be so lowered to cause a misfire, and when more than 10 wt %,
the sensitivity will become too keen to handle the gun safely. When
the borosilicate powder is less than 3 wt %, the sensitivity could
be so lowered to cause a misfire, and when more than 9 wt %, the
sensitivity will become too keen to handle the gun safely.
[0032] As for the chemical binder, a mixture of arabian gum,
tragacanth and gelatin may be preferably used in the present
invention.
[0033] The mixture of acacia, tragacanth and gelatin mixed with a
weight ratio of 9:5:1, is used preferably with an amount of 0.1-0.2
wt %, when being less than 0.1 wt %, the adhesiveness of the primer
powder will become so weak to cause loss of primer powder, and when
more than 0.2 wt %, the sensitivity of the primer will be
lowered.
[0034] For preparing the primer powder composition according to
above preferred embodiment of the present invention, mixing a
certain amount of wet DDNP and tetracene which have been weighed on
a dry basis, adding a shellac-coated potassium nitrate powder,
nitrate ester and a borosilicate powder with agitating to prepare a
wet explosive powder mix.
[0035] The present invention will be further understood by the
following examples, which is provided for illustrative purposes
without any intention to restrict the scope of the present
invention.
EXAMPLES
Example 1
[0036] On a dry basis, 30 wt % of DDNP and 7.5 wt % of tetracene
was mixed together, to the resulted mixture, 37.5 wt % of a
shellac-coated potassium nitrate and 17 wt % of nitrate ester were
added and mixed, and then thereto 7.8 wt % of a borosilicate powder
and 0.2 wt % of a chemical binder which is a mixture of arabian
gum, tragacanth and gelatin with a mixing ratio of 9:5:1 were added
and mixed thoroughly, in a mixer.
[0037] The shellac-coated potassium nitrate was prepared by adding
2 liter of ethyl alcohol to 1 kg of dried potassium nitrate to wet,
adding 80 ml of a shellac resin solution, stirring the mixture
sufficiently for one hour or more, allowing to stand it for 12
hours or more, removing the excessive ethyl alcohol, drying and
sieving the resulted product.
[0038] The resulted mixture, as a primer powder, was charged into a
cup (40) represented in FIG. 1, sealed with a foiling paper (20)
and compressed. The cup (40) charged with the primer powder (30)
was coupled with an anvil (10) in a coupler, covered with a lacquer
and dried at 45.about.55.degree. for 72 hours to finally give a
primer.
Comparative Example 1
[0039] A primer powder composition was prepared by the same method
as represented in the example 1, except that 36 wt % of lead
styphnate and 4 wt % of tetracene were mixed together, and thereto
39.8 wt % of barium nitrate, 16 wt % of antimony sulfide, 4 wt % of
an aluminum powder and 0.2 wt % of a chemical binder were added and
mixed.
Comparative Example 2
[0040] A primer powder composition was prepared by the same method
as represented in the example 1, except that uncoated potassium
nitrate, instead of the shellac-coated potassium nitrate was used
in an amount of 37.5 wt %.
[0041] Sensitivity Test
[0042] With those primers obtained from example 1 and comparative
examples 1 and 2, test on sensitivity was carried out, and the
results were represented in Table 1. The sensitivity test on a
small pistol primer was based on the national defense
specification. 20 bullets were used for each example and
comparative examples and average data thereof were used in Table
1.
2TABLE 1 (unit: inch) Standard Comparative Comparative Example 1
Weight of a Ball value example 1 example 2 1.sup.st 2.sup.nd
3.sup.rd 1.94 Oz H + 4s 11 8.60 11.30 7.98 8.02 7.53 1.94 Oz H - 2s
1 3.62 2.91 2.70 2.14 2.86 1.94 Oz H 5.28 5.25 4.46 4.10 4.42 1.94
Oz S 0.83 1.39 0.88 0.98 0.78 1.94 Oz
[0043] H: average fire height.
[0044] s: standard deviation, when s value is high, it is admitted
as being out of the required standard sensitivity level, even
though the average fire height (H) is included in the standard
level.
[0045] H+4s: limitation in sensitivity of the primer, which means
the fire should be within a certain height of drop weight,
i.e..sub.2 impact energy.
[0046] H-2s: safety of the primer, which means the fire should not
occur at a certain height or less of drop weight, i.e..sub.2 impact
energy.
[0047] As represented by above table 1, the sensitivity of the
primer powder composition obtained from the example 1 satisfies the
standard level, but does not show great difference with the
sensitivity of the composition of comparative example 1. However,
the primer powder composition obtained from the comparative example
2 is found not to satisfy the standard sensitivity level.
[0048] Speed, Pressure, Precision and Performance Test
[0049] With those primers obtained from example 1 and comparative
examples 1 and 2, test on speed, pressure and performance was
carried out respectively, and the results were represented in Table
2. The test was done by 9 mm Pistol Round, wherein the speed was
measured by using the Piezo Ballistic Computer System and a screen
photo electric speedometer, and the pressure was measured with a
cylinder pressure meter.
[0050] Specifically, the speed was determined by measuring the time
taken for the bullet to depart from the muzzle to pass through two
screens at a certain distance and then dividing the distance
between said screens with the time. The pressure was measured with
a PCB transducer, and the piezoelectric effect was plotted to P-T
for determination. The precision was measured with a test barrel by
firing 5 bullets per each trial for five times to a target provided
at a distance of 25 yard front, and determined by the average value
of the maximum distribution.
[0051] The performance test was carried out by checking out the
deterioration in performances, after being stored samples at high
temperature such as 52.degree., at a room temperature 21.degree.
and at a low temperature such as -40.degree. respectively for 4
hours.
3TABLE 2 Comparative Example 1 Test (unit) Standard level example 1
(21.degree. C.) Speed (ft/sec) 1,125 .+-. 50 1,124 1,161 Pressure
(psi) 35,700 or less 24,100 30,900 Precision (inch) 3 or less 1.8
0.8 Performance At room temperature No adverse No adverse No
adverse (21.degree. C.) effect on the effect on the effect on At
low temperature performance performance the (-40.degree. C.)
performance At high temperature (52.degree. C.)
[0052] As represented in above table 2, the primer powder
composition of example 1 satisfies the standard level in each
speed, pressure, precision and performance test, and does not show
great differences in test results, with the primer powder
composition of comparative example 1.
[0053] The primer which contains the primer powder composition for
small caliber ammunition according to the present invention: is a
non-toxic primer being free of hazardous heavy metal, thereby
having effects of protecting the health of an individual shooter
and the environment, thus being environmentally friendly; satisfies
the standard level concerning explosion sensitivity of a bullet,
bullet properties including speed, pressure and precision and
performances: and prevents sparks generated upon firing and
contaminants which cause corrosion in the arms.
* * * * *