Field ofthe Invention
The present invention relates to an agrochemical formulation comprIsmg
combination of two fungicidal components namely, Hexaconazole and
Carbendazim in the form of a suspension concentrate formulation. The stable
suspension concentrate is characterized in using appropriate mixture of
surfactants and anti caking agents preventing crystal growth of the fungicides.
The resultant formulation provided a method for controlling blight, rust and
foliar diseases of a large no. of crops such as apple, chili, paddy, groundnut,
banana, tomato, cereals and cotton crop.
Background of the invention and the related Prior Art
Hexaconazole is a systemic triazole fungicide with protective and curative action
and effective against sheath blight of paddy, powdery mildew on crops, leaf spots
and blight on agricrops. It is effective against rust and leaf spots, plantation crops
inhibiting ergosterol biosynthesis.
Hexaconazole is the common name of (+1-) alpha-butyl-alpha-(2,4dichlorophenyl)-
1,2,4- triazole-l-ethanol. It is a white to off white powder with
the following physic - chemical properties:
M.P. - 1110 C
B.P. - 490.30Cat 760 mm kg
V. P. - 0.018 mpa (20oC)
Solubility - water - 0.017 g 11 at 20°C
OCM - 331, methanol 246, acetone 164, ethyl acetate 120, toluene
59, hexane 0.8 (in gil at 200 C).
Stability - Stable to hydrolysis and photo stable in water. It rapidly degrades in
soil.
2
Carbendazim is systemic fungicide with protective and curative action. It acts by
inhibiting development of the germ tubes, the formation of aspersoria and the
growth of mycelia.
Carbendazim is the common name of methyl benzimidazol-2-ylcarbamate. It is a
buff colored powder with the following physico-chemical properties:
M.P. - 302-307oC(decomp)
V.P. - 0.09 mpa (20oC)
Sp. Gr. - 1.45 (20oC)
Solubility- water - 29 mg/l (ph 4), 8 mg/l (ph 7), 7 mg/l (ph 8) at 240C
DMF 5, acetone 0.3, ethanol 0.3, ethyl acetate 0.135, benzene 0.036,
hexane 0.0005 (in gil at 24oC)
Stability - decomposes at m.pt. Stable in acidic and alkaline solution at room
temp.
Both hexaconazole and carbendazim have high melting point and are very poorly
soluble in water. Hexaconazole has high solubility in organic solvents and is
formulated in the form of emulsifiable concentrate and also as suspension
concentrate.
Carbendazim has very poor solubility in organic solvents and hence is formulated
as wettable powder and suspension concentrate.
It is common practice to formulate solid, substantially water insoluble pesticides
in the form of aqueous suspension. Such suspension concentrates are very
sensible systems regarding physical and chemical stability. A particular problem
is the crystal growth, e.g. by Ostwald ripening of the active ingredient during
relatively short time of shortage. Crystal growth by Ostwald ripening generally
occurs when smaller crystals (which have a large total area than bigger crystals)
dissolve in the aqueous phase, to nucleation sites of the bigger crystals. As a
result the crystal of the active ingredient may aggregate and sediment. The
formulation becomes inhomogeneous during preparation, filters and nozzles of
the spray equipment can block and the biological efficacy may be reduced.
WO 2000035284AI describes a suspension concentrate formulation of a triazole
fungicide which is substantially insoluble in water and describes combination of
surfactants for the prevention of crystal growth.
3
EP 1139756AI describes suspension concentrate formulation of triazole
fungicide and combination of phosphate esters, alkylphenyl ethoxylate and
vinylpyrolidone/styrene block polymer for the prevention of crystal growth of
triazole fungicide.
WO 2009082939AI describes an aqueous suspension concentrate composition of
tebuconazole (triazole fungicide) stabilization with non-ionic dispersing agent
and anionic dispersing agent.
US Patent 5,393,770 discloses that the fungicidal activity of
benzyltriazolylcyclopentanes of a fungicidal substance is improved by
polyoxyalkylene alkyl ether, and also describes an emulsion and solution
composition containing polyoxyalkylene.
In addition, US Patent 5,905,072 discloses that the activity of various kinds of
fungicides is increased by a variety of non-ionic surfactants such as
polyoxyethylene alkyl ethers.
WO 2011095134 AI describes a combination formulation of a triazole, stobilurin
and benzimidazole fungicide for preventing and combating pathogenic damage in
plant. Attempts have been made to combat fungal diseases in plants. Hitherto US
4835169A describes combination formulation of a triazole fungicide (UK P NO
2136423B) and carbendazim in the form of a wettable powder and suspension
concentrate. The formulation was reportedly effective in controlling powdery
mildew, black rot and foliar diseases on several crops. The wettable powder
formulation contained 77% of fungicide (Triazole + carbendazim) and the
suspension concentrate contained 46% of fungicide (triazole + carbendazim).
Thus, there is further need in the art for a low dose effective formulation of
fungicide to cover broad spectrum diseases on agricrops. The other need of the
art are met by a stabilised suspension concentrate formulation of Hexaconazole
in combination with carbendazim by using appropriate mixture of surfactant
and anti-caking agents to prevent crystal growth. Specifically the present
invention describes an aqueous suspension concentrate composition containing
a blend of polyoxyethylene alkyl ether which is water soluble or water
dispersible at room temperature, and is a substance known for increasing
efficacy of various kinds of fungicides or expected to have action for increasing
efficacy. Particular the crystal growth formation and gelling behaviour was
controlled by properly selecting anti gel forming and anti-caking agents selected
from one or more of the group consisting of ethylene glycol, diethylene glycol,
propylene glycol, and dipropylene glycol and alkylated ethoxylated phosphate
4
esters. The weight ratio of polyoxyethylene alkyl ether( alkyl phenol ethoxylates)
to anti- gel forming and anti- caking agent is 1:1 to 1:8.
The crystal growth inhibitors provided here with are particularly suitable for
triazole fungicides which are substantially insoluble in water and solid at 250 C.
They are readily available, easy to handle relatively nontoxic and have no
undesired effects on plants. The compositions are stable without any crystal
growth of active ingredient. After dilution with water spray mixture is applied
without any technical problem and exhibited full biological efficacy.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a novel fungicide formulation to control
broad spectrum of fungal diseases on agricrops.
It is yet a further object of the invention to provide fungicidal composition
comprising suspension of carbendazim and hexaconazole which are established
by combination of suitable surfactants.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a stable aqueous suspension concentrate
composition comprising hexaconazole and carbendazim containing wetting and
dispersing agents such as sodium or potassium salts of alkylated ethoxylated
phosphate esters, sodium salts of alkyl sulphates and polyoxyethylene alkyl
ethers such as fatty alcohols- cetyl alcohol, stearyl alcohol and cetostearyl
alcohol and anti-gel or anti-caking agent selected from one or more of the group
consisting of ethylene glycol, diethylene glycol, propylene glycol and diproyleneglycol.
The stable aqueous suspension concentrate composition according to the
present invention can additionally contain rheology modifier, preservative and
anti-foaming agent.
Proper selection of polyxyetylenee alkyl ethers, anti gel forming and anti caking
agent and dispersant in the stable aqueous suspension composition is most
important in order to prevent the gel formation in the preparation and cake
formation during storage.
Polyxyalkylene alkyl ethers used in the present invention has 12 to 18 carbon
atoms and the average added mole number of polyoxyalkylene oxide is 7 to 20.
5
Anti gel forming and anti-caking agent used in the present invention is glycol
based aqueous solvent selected from ethylene glycol, diethylene glycol,
dipropylene glycol and propylene glycol. However, propylene glycol is preferred
in order to maintain the preparations anti caking effect during storage. Here anti
gel forming and anti caking agent also acts as anti-freezing agent.
The dispersing agent used are from styrenated alkyl phenol ethoxylate
phosphate ester sodium or potassium salts and more preferably tristyrenated
alkyl phenol ethoxylated phosphate ester potassium salt having ethylene oxide
varying from 10 moles to 20 moles and preferably 16-20 moles.
As wetting agent sodium lauryl sulphate, dialkyl naphthalene sulphonate, dialkyl
succinate, polyoxyalkylene alkyl ether, polyoxyalkylene alkyl ether sulphate can
be used. The wetting agent used in the preparation is the combination of sodium
lauryl sulphate and polyoxyalkylene alkyl ether.
As rheology modifier, polysaccharides which can improve viscosity in aqueous
solution phase, such as xantham gum, guar gum etc. can be used, but preferably
xantham gum can be used. Clay mineral such as bentonite is not effective because
clay mineral may cause caking during storage. Rheology modifier used in the
preparation is Rhodopol 23 and it is main ingredient in xantham gum.
As preservative in the present invention, benzisothiazoline or phenols can be
used. The present invention uses Proxel GXL comprising benzisothiazoline as
main ingredient.
As antifoam agent usable in the present invention, silicon based anti-foaming
agent can be used. Anti foam 7133 (Momentive USA) is used in the preparation of
the present invention.
Table -1
Preparation 1 2 3
HEXACONAZOLE 3 2 1
CARBENDAZIM 32 35 37
ETHOXYLATED PHOSPHATE 3 3 3
ESTER SALT
POLYOXYALKYLENEALKYL 1.5 1.5 1.5
ETHER
SALTS OF ALKYL SULPHATE 0.5 0.5 0.5
6
POLYOL 4 4 4
SILICONE ANTIFOAM 0.30 0.30 0.30
PROXALGXL 1.0 1.0 1.0
RHODOPOL 23 0.15 0.15 0.15
DMWATER 54.55 52.55 51.55
TOTAL 100 100 100
Table - 2
Preparation 4 5 6
HEXACONAZOLE 3 2 1
CARBENDAZIM 37 35 32
ETHOXYLATEDPHOSPHATE 3.0 3.0 3.0
ESTER SALT
POLYOXYALKYLENEALKYL 2.0 2.0 2.0
ETHER
SALTS OF ALKYL SULPHATE 2.0 2.0 2.0
POLYOL 6 6 6
SILICONE ANTIFOAM 0.6 0.6 0.6
PROXALGXL 2.0 2.0 2.0
RHODOPOL23 0.2 0.2 0.2
DMWATER 44.2 47.2 51.2
TOTAL 100 100 100
Table - 3
Preparation 7 8 9 10 11
HEXACONAZOLE 3 3 3 3 3
CARBENDAZIM 37 37 37 37 37
ETHOXYLATED
PHOSPHATE ESTER
SALT 3 5 7 4 6
POLYOXYALKYLENE
ALKYL ETHER 3 2 1 2.5 0.5
SALTS OF ALKYL
SULPHATE 1 2 1 1.0 2.5
POLYOL 8 6 4 5 10
SILICONE ANTIFOAM 1.0 0.8 0.6 0.5 0.3
7
PROXYLGXL 1.5 2.0 2.5 1.0 3.0
RHODOPOL 23 0.15 0.20 0.22 0.18 0.16
DMWATER 42.35 42 43.68 45.82 37.54
TOTAL 100 100 100 100 100
(All above preparations are in percent mass/mass)
Evaluations of storage stability of the aqueous suspension concentrate
composition
To evaluate the storage stability of the preparations the samples were observed
by the naked eye to see the presence of caking while they were maintained at
elevated conditions.
To evaluate stability of the aqueous suspension concentrate each 50 ml of glass
bottles was charged with 40 ml of test samples, covered, stored in oven
maintaining 54(±2)oC for two weeks, and then observed for change of the
appearance.
The test results are shown in table 4. The aqueous suspension concentrate of the
preparations exhibited good stability and a few preparations exhibited cake
formation with increase in viscosity during storage.
Table 4
Preparation Appearance after
Storage
1
2
3
4
Good
Good
Caking
Good
8
Preparation
7
8
9
10
Appearance after
Storage
Good
Good
Caking
Caking
5
6
Green house test
Good
Good
11 Good
Under greenhouse conditions the hexaconazole and carbendazim combination
formulations in the form of suspension concentrate were tested against various
pathogens like Rhictonia solani, Ustilago sp., Uncinula necator, Venturia
inaequalis,Phakopsora pachyrhizi, Phakopsora Meibomiae, Podosphaera xanthn
Sphaerotheca fuliginea on paddy,grapes,soyabean,apple and cucurbit crops and
found that the said combination has given much better control of diseases on
lower dosages and apart from the disease control also provided very good phytotonic
effect.

WE CLAIM:
1. An aqueous suspension concentrate composition containing hexaconazole
and carbendazim; dispersing agent potassium salt of tristyrenated alkyl
phenol phosphate ester; wetting agents polyoxyalkylene alkyl ether and
sodium salt of alkyl sulphate; anti-gel and anti-caking agent, rheology
modifier and anti-microbial agent.
2. The aqueous suspension concentrate composition as claimed in claim 1,
where the fungicidal composition is carbendazim (32-37%) and hexaconazole
(1-3%) by weight based on the composition.
3. The aqueous suspension concentrate composition as claimed in claim 1,
where the fungicidal active ingredient is 40% by weight based on the
composition.
4. The aqueous suspension concentrate composition as claimed in claim 1,
where in the wetting agent is polyoxyalkylene alkyl ether and sodium salt of
alkyl sulphate.
5. The aqueous suspension concentrate composition as claimed in any of the
preceding claims 1-4, where in the polyoxyalkylene alkyl ether has 12-18
carbon atoms.
6. The aqueous suspension concentrate composition as claimed in claim 1,
where in the anti - gel forming and anti-caking agent is propylene glycol.
10
7. The aqueous suspension concentrate composition as claimed in claim 6,
where in the anti-gel forming and anti-caking agent is 4 - 10% by weight
based on the composition.
8. The aqueous suspension concentrate composition as claimed in claim 1,
where in the weight ratio of wetting agent polyoxyalkylene alkyl ether to anti
gel forming and anti-caking agent is 1:2 to 1:4.
9. The aqueous suspension concentrate composition as claimed in claim 1,
further comprising of one or more additives selected from the group
consisting of dispersing agent, wetting agent, preservative, rheology modifier,
anti-gel and anti-caking agent and anti-foaming agent.
10.The aqueous suspension concentrate composition as claimed in any of the
preceding claims substantially as herein described with reference to forgoing
examples.