Technical Field
[1] The present invention relates to pyrotechnic self-combustible riot control com
positions that have low toxicity and ignition temperatures.
Background Art
[2] CS is well-known riot control agent used by law enforcing agencies during civil di s
turbances and one of the most potent lachrymator skin irritants. CS was synthesized via
Knoevenagel condensation of o-chlorobenzaldehyde with malononitrile in the presence
of different bases as a catalyst in water (U.S. patent no. 7,732,631).
[3] Pyrotechnic compositions are composed of an inorganic oxidizer (potassium
chlorate, nitrate or perchlorate) and a combustible organic fuel (lactose or sucrose) to
chemically generate heat, light or color [1,2,3]. Some additives facilitate burning and
improve the processing of the composition [4,5]. Stabilizer avoids drowning of the
compositions owing to melting of one of the constituents. Metal oxide or carbonates
such as magnesium carbonate or magnesium hydroxide are widely used as a stabilizer
and coolant. Organic dyes such as 1,4-dihydroxy anthraquinone (orange),
l-(p-tolylamino)-4-hydroxy anthraquinone (violet), 1-methylamino anthraquinone
(red), and 4,4'-methylidyne-bis-3-methyl-l-phenyl-2-pyrazolin-5-one (yellow) are
used in smoke compositions. Binders are widely used to prevent segregation of
oxidizers and fuels in pyrotechnic formulations. Use of a binder also increases the h o
mogeneity of a mixture and possibility of successful ignition. Polymers have been in
corporated into pyrotechnic and propellant compositions as binders to improve me
chanical properties, sensitivity and manufacturing output of the compositions.
[4] There have been recent efforts to develop pyrotechnic disseminating riot control
composition with various specialty binders. Polyester resin (Bryant et. al. U.S. patent
no. 3,391,036) was used to obtain solid and desired shaped charges. Other polymeric
binder based on aromatic sulphur containing epoxy resin was disclosed in Drake et. al.
U.S. patent no. 3,712,233 which described caseless munition for the dissemination of
CS without flaming. Kramer patent no. DE 3418116 C 1 describes pyrotechnic com
position including CS or CN as irritant and polyvinyl acetate as binder to obtain
desired shaped munitions. Aliphatic sulfur-containing organic compound cured with
aliphatic sulfur containing epoxy resin (Flynn et. al. U.S. patent no. 4,190,471), nonhalogenated
epoxy based resin cured with an organic acid or organic acid anhydride
(Kott et. al. U.S. patent no. 3,704,187) and liquid epoxy based resins with an organic
amine curing agent (Wernett et. al. U.S. patent no. 3,467,558) were used in riot control
compositions as binders.
[5] Prior art riot control composition did not meet the need for composition which has
low ignition temperature and toxicity. Many of compositions disclosed in prior art may
release toxic and corrosive decomposition products (e.g. hydrogenated or aromatic
halogen, hydrogen sulfide) during combustion.
Disclosure of Invention
Disclosure
[6] It is an object of the present invention to provide a smoke producing pyrotechnic
composition for dissemination of CS. An additional object is to provide a munition
which has low ignition temperature and toxicity. Low ignition temperature minimizes
creation of thermal degradation products which are potentially hazardous to human
health.
[7] Sucrose, potassium chlorate, magnesium carbonate hydroxide pentahydrate and
9,10-anthraquinone are pre-ground to a fine powder and passed through a # 120-140
mesh sieve. CS is synthesized via Knoevenagel condensation of o-chlorobenzaldehyde
with malononitrile in the presence of 1-methyl imidazole as a catalyst in water as
described in literature [9]. Purity and yield of CS obtained are >99 and melting point
is 93-94 °C. Certain amount of polycarbonate (PC) is dissolved in tetrahydrofuran
(THF) at 40+5 °C. The amount of THF is 1.5 fold excess of total weight of com
position. After dissolution of PC, CS and other powdered ingredients were added to
solution. The resultant solution was maintained at 40+5 °C at least for 3 hours during
stirring and removing the solvent. The solution is removed from heat and allowed to
dry. The dry mixture is added to ball mill and ground back into a fine powder for 30
minutes. Powdered mixture is compressed using tablet pressing machine at a pressure
of 7,000-8,000 pounds to achieve a tablet density of 1.2-1.4 g/cm3. The ignition tem
peratures of the compositions were determined by differential thermal analysis (DTA).
Burning rates were measured at 20+5 °C. The burning rate gives information on the
speed at which the tablets burn.
[8] The following examples are given to better illustrate the present invention without
limiting it to what is specifically described.
Disclosure of Invention
Technical Problem
Technical- Problem
[9] In pyrotechnic composition, ignition temperature and burning rate are very important
parameters. The burning rate determines the amount of evolved gas in a specific time
period. The burning rate must not be too slow or fast to obtain effective munitions.
Ignition temperature is the temperature at which strong exothermic reaction begins. If
the ignition temperature is high (>300 °C), CS may decompose to toxic products like
hydrogen cyanide. High temperatures cause also undesirable darkening of the
produced smoke and a decrease in smoke production due to burning of components.
Additionally, CS based munitions may cause undesired fires in closed areas. It is rec
ommended that CS based pyrotechnic mixture should be burnt below 300 °C.
Solution to Problem
Technical- Solution
] The present invention provides self-combustible CS based pyrotechnic compositions
which have low toxicity and ignition temperature. PC was used as a flame retardant in
riot control composition for the purpose of preventing undesired fires in enclosed area.
PC was also able to bind solid components together to form hard tablets as a binder.
Carbonate salts are added to the composition to prevent auto catalytic decomposition
of the oxidizer and to act as a buffer. These salts also function as a coolant when the
composition is combusted. In the present invention, magnesium carbonate hydroxide
pentahydrate ((MgC0 3 ) 4-Mg(OH)2-5H20 ) was preferred as a coolant and stabilizer. It
also served as a flame suppressant.
] The present invention provides pyrotechnic riot control compositions which have
relatively low ignition temperatures (<300 °C) to prevent decomposition of CS and
undesired fires.
Advantageous Effects of Invention
Advantageous Effects
] In the present invention, PC was used as binder and fire retardant to obtain CS based
compositions with low ignition temperature. PC is a light weight polymer and has
excellent flame retardant and self-extinguishing properties. PC can be injection/blow
molded and extruded. It has good stiffness, melt viscosity, impact strength, modulus,
transparency, light transmission, dimensional stability and thermal stability. Poly
carbonate was used in gas generant compositions as a binder for inflating a safety bag
in the vehicle (Lundstrom et. al. U.S. patent no. 6,435,552 ). Therefore, it is widely
used in the fields of optical equipment, construction, automobiles, electrical and
electric devices [6,7,8] due to its moldability. In the compositions, sucrose and
potassium chlorate were used as fuel and oxidizer, respectively. 9, 10-anthraquinone
and magnesium carbonate hydroxide pentahydrate were used as smoke component and
coolant in the formulation, respectively.
] The present invention provides pyrotechnic riot control compositions which have
burning rate varying from 0,017-0,041 g/s and ignite at temperatures between 210-220
°C.
Examples
Example 1
[14] In one embodiment, a pyrotechnic formulation having 25% by weight oxidizer/fuel
and 30 % by weight CS is prepared according to Table 1.
[15] Table 1: 25% oxidizer/fuel formulation with 30% CS
[Table 1]
[16] The burning rate and ignition temperature of the tablets prepared from this com
position were 0,020 g/s and 210 °C, respectively. The tablet was ignited by first fire,
after ignition, flame was extinguished. The composition continued to burn without
flame. The total weight of the tablet was 0,87 g and the weight of the ash was 0,17 g.
The smoke produced had good volume.
Example 2
[17] In one embodiment, a pyrotechnic formulation having 27,5 % by weight oxidizer/
fuel and 10 % by weight coolant is prepared according to Table 2.
[18] Table 2: 27.5% oxidizer/fuel formulation with 10% coolant
[Table 2]
Component Type Component Wt.%
Riot control agent CS 25
Binder PC (TRIREX 3022 IR) 7
Fuel Sucrose 27,5
Oxidizer Potassium chlorate 27,5
Stabilizer and coolant Magnesium carbonate 10
hydroxide pentahydrate
Smoke 9,10-Anthraquinone 3
[19] The burning rate and ignition temperature of the tablets prepared from this com
position were 0,029 g/s and 217 °C, respectively. The tablet ignited as in Example 1.
The total weight of the tablet was 0,83 g and the weight of the ash was 0,19 g. The
smoke produced had good volume.
Example 3
[20] In one embodiment, a pyrotechnic formulation having 30 % by weight oxidizer/fuel
and 20 % by weight CS is prepared according to Table 3.
[2 1] Table 3: 30% oxidizer/fuel formulation with 20% CS
[Table 3]
[22] The burning rate and ignition temperature of the tablets prepared from this com
position were 0,035 g/s and 211 °C, respectively. The tablet ignited as in Example 1.
The total weight of the tablet was 0,79 g and the weight of the ash was 0,15 g. The
smoke produced had good volume.
Example 4
[23] In one embodiment, a pyrotechnic formulation having 27,5 % by weight oxidizer/
fuel and 8 % by weight coolant is prepared according to Table 4.
[24] Table 4: 27.5% oxidizer/fuel formulation with 8% coolant
[Table 4]
Component Type Component Wt.%
Riot control agent CS 25
Binder PC (TRIREX 3022 IR) 7
Fuel Sucrose 27,5
Oxidizer Potassium chlorate 27,5
Stabilizer and coolant Magnesium carbonate 8
hydroxide pentahydrate
Smoke 9,10-Anthraquinone 5
[25] The burning rate and ignition temperature of the tablets prepared from this com
position were 0,020 g/s and 217 °C, respectively. The tablet ignited as in Example 1.
The total weight of the tablet was 0,78 g and the weight of the ash was 0,14 g. The
smoke produced had good volume.
Example 5
[26] In one embodiment, a pyrotechnic formulation having 27,5 % by weight oxidizer/
fuel component and 7 % by weight coolant is prepared according to Table 5.
[27] Table 5: 27.5% oxidizer/fuel formulation with 7% coolant
[Table 5]
[28] The burning rate and ignition temperature of the tablets prepared from this com
position were 0,034 g/s and 214 °C, respectively. The tablet ignited as in Example 1.
The total weight of the tablet was 0,80 g and the weight of the ash was 0,16 g. The
smoke produced had good volume.
Example 6
[29] In one embodiment, a pyrotechnic formulation having 25 % by weight oxidizer/fuel
and 15 % by weight coolant is prepared according to Table 6.
[30] Table 6: 25% oxidizer/fuel formulation with 15% coolant
[Table 6]
Component Type Component Wt.%
Riot control agent CS 25
Binder PC (TRIREX 3022 IR) 7
Fuel Sucrose 25
Oxidizer Potassium chlorate 25
Stabilizer and coolant Magnesium carbonate 15
hydroxide pentahydrate
Smoke 9,10-Anthraquinone 3
[31] The burning rate and ignition temperature of the tablets prepared from this com
position were 0,017 g/s and 213 °C, respectively. The tablet ignited as in Example 1.
The total weight of the tablet was 0,81 g and the weight of the ash was 0,17 g. The
smoke produced had good volume.
Example 7
[32] In one embodiment, a pyrotechnic formulation having 10 % by weight binder
component and 25 % by weight CS is prepared according to Table 7.
[33] Table 7: 10% binder formulation with 25% CS
[Table 7]
[34] The burning rate and ignition temperature of the tablets prepared from this com
position are 0,024 g/s and 218 °C, respectively. The tablet ignited as in Example 1. The
total weight of the tablet was 0,84 g and the weight of the ash was 0,17 g. The smoke
produced had good volume.
Example 8
[35] In one embodiment, a pyrotechnic formulation having 29,5 % by weight oxidizer/
fuel and 25 % by weight CS is prepared according to Table 8.
[36] Table 8: 29,5% oxidizer/fuel formulation with 25% CS
[Table 8]
Component Type Component Wt.%
Riot control agent CS 25
Binder PC (TRIREX 3022 IR) 7
Fuel Sucrose 29,5
Oxidizer Potassium chlorate 29,5
Stabilizer and coolant Magnesium carbonate 6
hydroxide pentahydrate
Smoke 9,10-Anthraquinone 3
[37] The burning rate and ignition temperature of the tablets prepared from this com
position are 0,041 g/s and 213 °C, respectively. The tablet ignited as in Example 1. The
total weight of the tablet was 0,87 g and the weight of the ash was 0,12 g. The smoke
produced had good volume.
[38] The relative amounts of CS, oxidizer and fuel were held constant in Figure 1. The
burning rates ranging from 0,020-0,034 g/s are indicated on the plot. The relative
amounts of smoke component, binder and coolant were held constant in Figure 2. The
burning rates ranging from 0,020-0,035 g/s are indicated on the plot. The relative
amounts of smoke component, binder and CS were held constant in Figure 3. The
burning rates ranging from 0,017-0,041 g/s are indicated on the plot. Referring to
Figure 1, 2 and 3, desired burning rate can be obtained by varying relative amounts of
components in the compositions. Upon ignition, only white smoke was produced for
each of the compositions in Figure 1, 2 and 3.
Brief Description of Drawings
Description Of Drawings
[39] Figure 1 is a ternary plot showing variation of burning rates of the compositions with
relative amounts of binder, coolant and smoke component.
[40] Figure 2 is a ternary plot showing variation of burning rates of the compositions with
amounts of oxidizer, CS and fuel.
[41] Figure 3 is a ternary plot showing variation of burning rates of the compositions with
amounts of oxidizer, coolant and fuel.
Best Mode for Carrying out the Invention
Best Mode
[42] The preferred composition of riot control formulations have the following com
position (Example 2):
[Table 9]
[43] The burning rate for Example 2 having 27,5 % by weight oxidizer/fuel and 10 % by
weight coolant is within desired burning rate for tear gas hand grenades and cartridges.
Industrial Applicability
[44] Upon ignition, the heat produced by reaction of fuel and oxidizer causes CS and
9,10-anthraquinone to sublime. The compositions produce tear gas smoke which
causes a temporary incapacitating. These compositions can be used as tear gas
munitions in hand grenades or cartridges. They have applications in riot control and
events requiring special operations by law enforcement personnel.
References Cited
[45] [Table 10]
Other References
[46] [1] B. Berger, Parameters influencing the pyrotechnic reaction, Propellants Explos.
Pyrotech. 30 (2005) 27-35.
[47] [2] M.E. Brown, Some thermal studies on pyrotechnic compositions, Therm. Anal.
Calorim. 65 (2001) 323-334.
[48] [3] X.M. Qian, Y. Wang, C.G. Feng, Investigation of thermal decomposition of
KC103/CuO/S/Mg-Al/C 6Cl6 system by accelerating, Acta Phys. Chim. Sin. 17 (2001)
70-73.
[49] [4] M. Hemmila, M. Hihkio, K. Linnainmaa, Evaluation of the acute toxicity and
genotoxicity of orange, red, violet and yellow pyrotechnic smokes in vitro, Propellant
Explos. Pyrot. 32 (2007) 415-422.
[50] [5] M. Fathollahi, S. M. Pourmortazavi, S. G. Hosseini, The effect of the particle size
of potassium chlorate in pyrotechnic compositions, Combust. Flame 138 (2004)
304-306.
[51] [6] Zhang WC, Li XM, Guo XY, Yang RJ. Mechanical and thermal properties and
flame retardancy of phosphoruscon-taining polyhedral oligomeric silsesquioxane
(DOPO-POSS)/polycarbonate composites. Polymer Degradation and Stability 2010; 95
(12):2541.
[52] [7] Swoboda B, Buonomo S, Leroy E, Cuesta Lopez JM. Fire retardant poly(ethylene
terephthalate)/polycarbonate/tri-phenyl phosphite blends. Polymer Degradation and
Stability 2008; 93 (5):910 - 917.
[53] [8] Hoang DQ, Kim JH. Synthesis and applications of biscyclic phosphorus flame retardants.
Polymer Degradation and Stability 2008; 93 (l):36-42. [9] Pande A, Ganesan
K, Jain AK, Gupta PK and Malhotra RC. A novel eco-friendly process for the
synthesis of 2-chlorobenzylidenemalononitrile and its analogues using water as a
solvent. Organic Process Research and Development 2005;9(2): 133-136.

Claims
1.A pyrotechnic self-combustible riot control composition comprising;
a. CS as riot control agent,
b. Fuel,
c. Oxidizer,
d. Polycarbonate as binder,
e. Magnesium carbonate hydroxide pentahydrate as stabilizer,
f. Dye.
A pyrotechnic self-combustible riot control composition according to
claim 1, characterised in that it comprises fuel selected from the group
comprising sucrose or lactose.
A pyrotechnic self-combustible riot control composition according to
claim 1, characterised in that it comprises potassium chlorate as
oxidizer.
A pyrotechnic self-combustible riot control composition according to
claim 1, characterised in that it comprises one or more substance used
as dye selected from the group comprising 1,4 dihydroxy anthraquinone,
l-(p-tolylamino)-4-hydroxy anthraquinone, 1-
methylamino anthraquinone,
4,4-methylidyne-bis-3-methyl-l-phenyl-2-pyrazolin-5-one and 9,10 anthraquinon
as dye.
5.A pyrotechnic self-combustible riot control composition according to
claim 1, characterised in that it comprises;
a. 20% to 30% wt CS,
b. 25% to 30% wt sucrose or lactose,
c. 25% to 30% wt potasium chlorate,
d. 7% to 10% wt polycarbonate,
e. 6% to 15% wt magnesium carbonate hydroxide pentahydrate,
and
f. 3% to 5% wt 9,10 anthraquinone.
6.A method for making pyrotechnic self-combustible riot control com
position comprising steps of;
a. Sucrose, potassium chlorate, magnesium carbonate hydroxide
pentahydrate and 9,10-anthraquinone are pre-ground to a fine
powder and passed through a # 120-140 mesh sieve,
b. PC is dissolved in tetrahydrofuran (THF) at 40+5 °C,
c. After dissolution of PC, CS and other powdered ingredients
were added to solution,
d. The resultant solution was maintained at 40+5 °C at least for 3
hours during stirring and removing the solvent,
e. The solution is removed from heat and allowed to dry,
f. The dry mixture is added to ball mill and ground back into a
fine powder for 30 minutes,
g. Powdered mixture is compressed using tablet pressing machine
at a pressure of 7,000-8,000 pounds to achieve a tablet density of
1.2-1.4 g/cm3