Note: Descriptions are shown in the official language in which they were submitted.
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WO 98/03065 PCT/GB97/01951
~PROCESS FOR PREPARING STORAGE-STABLE PESTICIDE DISPERSION
~This invention relates to a process for preparing an
aqueous dispersion of polymeric microcapsules containing
S a supersaturated solution or supercooled melt of water-
insoluble materials. In particular, it is concerned with
providing aqueous dispersions of pesticidal material
which do not crystallise, so that a product with a high
content of active material can be provided which is
storage-stable. Storage-stable transportable aqueous
dispersions of pesticides are provided which can be
applied to crops and the like by conventional spray
technlques .
~5It is well known to encapsulate highly water-
insoluble pesticidal material in polymeric microcapsules,
in order that the pesticidal material can be applied to
cr~ps and the like. Such microcapsule formulations are
commoniy provided in the form of spray-dried powders,
whicn are rewetted prior to application. For example,
US-A-~160530 (Griffin) discloses a process for
encapsulating pesticides by melting the active material
and combining the melted material with a film-forming
polymer, such as a polyvinyl alcohol (PVA). The
mat~rials are then emulsified together and spray-dried.
A similar method is disclosed in US-A-4244836 (Hoechst).
For some applications, however, liquid concentrates,
-particularly aqueous concentrates, have substantial
advantages over dry formulations. Aqueous concentrates
are generally easier to formulate for field application,
and generate reduced possibility of lnhalation by a user.
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It lS known to prepare encapsulated pesticides as
wet formulations, i.e. as an aqueous dispersion of
microcapsules. However, such aqueous concentrates tend
to have a lower loading of active ingredient, and
therefore tend to be more costly to store and transport
than corresponding dry formulations. For instance, US-A-
4938797 includes an example of a wet formulation of
microcapsules in which the suspension has an active
ingredient content of 46% by weight.
It is known to prepare pesticide-containing dry
microcapsules by carrying out the encapsulation process
at an elevated temperature, either employing very low
amoun~s of solvent (so that when the dispersion cools the
pest~cide is encapsulated in the form of a supersaturated
solution) or by encapsulating a melt of the pesticide
resulting in microcapsules containing a supercooled melt.
~e have ~ound however that concentrated aqueous
formulations of microcapsules containing supercooled
melts or supersaturated solutions are not storage-stable,
since, on storage at ambient temperatures,
crystallisation of the pesticide occurs. This renders
the formulation unusable.
Surprisingly, it has been discovered that storage-
stable aqueous dispersions of microcapsules containing a
high loading of active product in the form of supercooled
melts or supersaturated solutions can be stabilised
against crystallisation by providing that the
microcapsules have a volume median particle size of not
more than 6~m, preferably not more than 5~m, more
preferably not more than 2~m. It has further been
discovered that crystallisation of the active product
from such dispersions can be reduced by avoiding the use
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W098/03065 PCTIGB97/01951
- of surfactants which form micelles under the conditions
of storage (and thereby facilitate transportation of the
- water-insoluble material through the aqueous phase,
resulting in crystallisation).
WO 95/07614 relates to the use of polymeric
stab lisers to alter the chemical potential of emulsion
particles in an oil-in-water emulsion, and thereby
inhibit Ostwald ripening. The use of such stabilisers in
suspension-emulsions is also disclosed, as are a number
of aqueous dispersing agents for such dispersions,
inc;uding a polyvinyl alcohol/polyvinyl acetate
copolymer. This reference also discloses certain
mic-ocapsule suspensions. There is no disclosure in WO
95/~7614 however of the desirability of selecting a non-
micellising surfactant, and of the need to avoid
sur-actants which do form micelles, in order to stabilise
pa~ iculate dispersions. In fact, the surfactant used to
sta~ilise the dispersions of microcapsules disclosed in
~O ~5/07614 is ATLOX 4991TM, an ethoxylated alcohol which
is a micellising surfactant.
PCT/US95/15534 discloses the preparation of dry
mic-ocapsules by spray-drying aqueous solutions of
mic-ocapsules containing PVA surfactants. There ls no
suggestion in PCT/US95/15534 however that the use of such
surfactants (or the use of any non-micellising
surfactant) is able to improve the long-term stability of
aqueous formulations.
Accordingly, in a first aspect of the invention,
there is provided a process for preparing a storage-
stable aqueous dispersion of a water-insoLuble material,
which process comprises emulsifying in water a non-
SUBSTITUT~ SHEET (RlJLE 26)
.
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W098/0306S PCT/GB97/01951
aqueous phase comprising a solution or a melt of the
water-insoluble material, so as to form emulsion
particles having a volume median particle size of not
more than 6~m, and carrying out a polymerisation process
to form from the emulsion particles an aqueous dispersion
of microcapsules, the said microcapsules having the said
water-insoluble material contained therein in the form of
a supersaturated solution or a supercooled melt, and
stabilising the dispersion with a non-micellising
surfactant, wherein the stabilised dispersion is
substantially free of micellising surfactant.
The amount and/or nature of the non-micellising
surfactant may be such that the solubility of the water-
insoluble material in the aqueous phase is not more thanlOOppm preferably not more than 50ppm, more preferably
not more than 5ppm.
The term "non-micellising" as used herein is
intended to mean a surfactant which does not form
micelles (which facilitate transport of the water-
insoluble material through the aqueous phase) under the
conditions used to store the stabilised dispersion.
The process of the invention generally includes the
step of storing the stabilised dispersion, for example
after pac~aging in a closed container.
The condltions of storage may be any conditions
appropriate to the particular dispersion and water-
insoluble material, but will generally be ambient
condi~ions.
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The tendency of a surfactant to form mlcelles
increases with the concentration of the surfactant. The
point at which micelles are formed is known as the
critical micelle concentration (CMC). In order to find
the CMC for a particular surfactant, the surface tension
of the surfactant is plotted against the log of its
concentration. Those surfactants which readily form
mlcelles, such as monomeric anionic and nonionic
surfactants, typically show a quite rapid reduction in
surface tension with concentration, until a specific
cor.centration for that surfactant (the CMC) at which the
reduction in surface tension ceases.
Such a plot is shown in Figure ~, which is a plot of
surface tension against log concentration for an
ethoxylated alcohol surfactant (shown as "-") and for a
polyv r.yl alcohol (shown as "-"). It can be seen that
the ethoxylated aLcohol forms micelles at and above a
ConCentratlon of lO-2s ~w/w. By contrast, the curve for
t~e DVA shows a gradually reducing surface ~ension with
concer,.ration with no clear change in behaviour,
indicative that no micelles are formed in this case. A
simple plot of surface tension against concentration can
therefore be carried out to determine whether the
surfactant forms micelles at the concentrations and under
the conditions employed in the formulation.
Most surfactants are such that, under essentially
all ~ractical conditions of use, they are "micellising"
and therefore unsuitable. Examples of such surfactants
include nonionic surfactants such as fatty alcohol
ethoxylates (alkoxylates), such as are employed in WO
9~/07614, fatty acid esters (and alkoxylates of fatty
acid esters), alkoxylated amines, ethylene oxide-
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propylene oxide copolymers, fatty acid alkoxylates (PAG
esters, specifically PEG esters), tall oil and rosin
ester alkoxylates, alkyl phenol alkoxylates, substituted
phenol alkoxylates; anionic surfactants such as dodecyl
benzene sulphonic acid and its salts, alkyl sulphates,
nonionic alkoyxlates phosphated or sulphated to produce
the corresponding phosphate ester or ether sulphate
' respectively and cationic surfactants such as cetyl
trimethyl ammonium chloride. Other micellising
surfactants can be found in reference works such as
"McCutcheons Emulsifiers & Detergents".
Clearly, there is a balance between the emulsifying
e fect and the tendency to form micelles (both of which
ncrease with surfactant concentration). It will be
appreciated that, between preferred surfactants and
unsuitable surfactants, there is a group of surfactants
~hich have some stabilising effect but which are not
preferred.
A surfactant may be used which forms micelles under
~he process conditions, provided that it does not form
micelles under the conditions of storage, since it is on
storage that crystal isation generally takes place.
As indicated above, the "non-micellising surfactant"
is one which is able to stabilise the dispersion such
that the dispersed microcapsules remain in suspension on
extended storage.
Without wishing to be constrained by theory, it is
thought that the surfactants in question inhibit
transportation of the water-insoluble material through
the aqueous phase, thereby reducing the likelihood of
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nucleatlon of the said material and of subsequent
crystallisation. By contrast, those surfactants which
have a strong ability to form micelles are thought to
promote transportation of the water-insoluble material
S through the aqueous phase, resulting in crystallisation.
In principle any surfactant can be used which has a
sufficient emulsifying effect when employed at a
concentration below its critical micelle concentration.
In practice, suitable surfactants tend to be polymeric
surfactants of relatively high molecular weight, for
example with 2 weight average molecular weight of at
leas~ 10,000. Lignosulphates with a weight average
molecular weight of at least 2,000 are also suitable.
A preferred stabilising surfactant a poly(vinyl
pyrrolidone), a co-poly(vinyl alcohol/acetate~ PVA, a co-
poly(vinyl pyrrolidone/acetate), a co-poly(vinyi
pyrrol done/acetate/alcohol), a co-poly(acrylic
acid/graft polyethyleneoxide), a co-
poly(alkyl(meth)acrylate), a lignosulphonate, a co-
poly(maleic anhydride/methyl vinyl ether), a co-
poly(maleic anhydride/diisobutylene), a carboxylated PVA,
a poly(styrene sulphonate), a poly(alkyl cellulose) or a
poly(ca~boxyalkyl cellulose). A particularly preferred
surfactant is a polyvinyl alcohol (~VA).
The aqueous dispersions of the present invention may
be packaged in a closed container for shipping and
transport purposes.
In a preferred embodiment, the stabilising
surfactant is added prior to the polymerising step and,
more preferably, prior to the emulsifying step.
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_ . . .. .
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2article size (vmd) may be measured, for example,
using a laser diffraction instrument, for example a
Malvern Mastersizer~.
As used herein, the term "water-insoluble material"
means a material which has a solubility in water of not
more than lOOppm, more preferably not more than 50ppm,
more preferably still not more than 5ppm.
The polymerisable material is preferably polymerised
in ar. interfacial reaction, and most preferably in an
.nterfacial condensation reaction. In a preferred
embodiment, the polymerisable material is a
polyisocyanate which is polymerised by means of a
condensation reaction with a polyamine.
Alternatively, the polymerisable material may be a
crosslinkable material which is used to coat the emulsion
par~ -ies by 2 coacervation method, and thereafter
crosslinked to form the microcapsules.
Both interfacial and coacervation methods involve
the preparation of an oil-in-water emulsion, followed by
either a condensation reaction at the oil/water interface
to produce a polymeric film, or the production of a
coacervate which can then deposit on the oil surface,
followed by film forming and hardening, which can take
place by a variety of processes. The condensation
reaction can for example be a multi-component reaction
between, for example:
acid chlorides and polyamines
isocyanates and polyamines,
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WO 98/03065 PCT/GB97/01951
rsocyanates and polyols,
or mixtures or the above.
Coacervates can be formed by any of the processes
t3ught in the art, for example using gelatine/gum arabic
The microcapsules in accordance with the invention
may be prepared by high shear mixing of a solution or a
melt containing the water-insoluble material (e.g.
pesticide), preferably a PVA (as an aqueous solution) to
enhance microcapsule formation, and one of the materials
for forming the microcapsules (e.g. a polymerisable
material for instance an isocyanate or a crosslinkable
material). The PVA acts as an emulsifier, and in some
systems, no further emulsifier may be required. It is
desirable however to add additional emulsifiers, which
may be of generally known type in order to produce the
desired emulsion of small particle size (provided that
tne emulsifiers are non-micellising as defined herein).
When the size of the emulsion is as desired, then the
othe~ polymeric cross-linker is added (e.g. polyamine),
to complete the interfacial polycondensation.
As indicated above, a preferred reactant for the
polycondensation is a polyamine, which is usually a water
soluble, reactive polyamine, such as diethylene triamine
or tetraethylene pentamine. These amines start to react
with the isocyanate at the interface as soon as they are
added to the emulsion. More complete control can
sometimes be achieved by using either a water-soluble
amine salt, or an oil-soluble amine salt, dissolved
respectively in the aqueous phase or the oil phase at an
early stage in the process (for example, before
emulsification). By virtue of the fact that they are
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WO 38~!~3~5 PCT/GB97/01951
salts, they do not immediately react with the isocyanate,
but do so promptly when the pH is adjusted to liberate
the free amine, whereupon cross-linking occurs.
The high shear mixing can be performed on a batch of
the ingredients, or may be conducted continuously (in-
line). In the former case, the time of addition or
release of the reactive amine is governed by the
processing time re~uired to form the emulsion with the
correct particle size distribution (which clearly is
ba~ch size dependent), whilst in the latter case, the
interfacial reaction can be better controlled, since the
amine can be added/released at any desired time simply by
choice of injection point in the process stream, thus
giving essentially complete control over the
urea/urethane ratio.
In a preferred embodiment, an additional non-
micellising surfactant is provided in the aqueous
dispersion. The dispersion may also preferably comprise
an antifreeze agent, for example an ethylene glycol or a
propylene glycol.
The water-insoluble material is preferably a
pesticidal material. The term "pesticidal material"
includes but is not limited to insecticidaL, miticidal,
herbicidal and fungicidal materials.
Suitable insecticidal materials are:
acrinathrin allethrin alpha-cypermethrin
amitraz azinphos-ethyl azinphos-methyl
benfuracarb benzoximate beta-cypermethrin
betacyfluthrin bifenthrin binapacryl
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bicallethrin bioallethrin S bioresmethrin
bioresmethrin bromophos bromopropylate
- buprofezin butacarboxim butoxycarboxin
cambda-cyhalothrin chlordimeform chlorfenvinphos
chl~rflurazuron chlormephos chlorobenzilate
chlorophoxim chloropropylate chlorpyrifos
chlorpyrifos- cyanophos cycloprothrin
methyl
cyfluthrin cyhalothrin cypermethrin
cyphenothrin deltamethrin demeton-S-methyl
dichlorvos dicofol dinobuton
dioxabenzafos dioxacarb disulfoton
ed~fenphos empenthrin endosulfan
EPNethiofencarb esfenvalerate ethoprophos
etofenprox etrimphos fenamiphos
fenazaquin fenitrothion fenobucarb
ferpropathrin fenthiocarb fenthion
fer.valerate flucythrinate flufenoxuron
formothion gamma-HCH hexaflumuron
hydroprene isofenphos isoprocarb
isoxathion malathion mephospholan
methidathion methoprene methoxychlor
mevinphos N-2,3-dihydro-3- parathion methyl
methyl-1,3-
thiazol-2-ylidene-
2,4-xylidene
permethrin phenothrin phenthoate
phosalone phosfolan phosmet
pirimiphos-ethyl pirimiphos-methyl profenofos
promecarb propaphos propargite
propetamphos pyrachlofos quinalphos
resmethrin tau-fluvalinate tefluthrin
tefluthrin temephos terbufos
terbufos tetrachlorinphos tetrachlorinphos
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tetradifon tetramethrin tralomethrin
tralomethrin tralomethrin triazophos
triazophos xylylcarb
Suitable fungicidal materials are:
azaconazole benalaxyl biteranol
bupirimate carboxin cyproconazole
difenoconazole dimethomorph diniconazole
ditalimfos dodemorph dodine
epoxyconazole ethoxyquin etridiazole
fenarimol fenpropidin fenpropimorph
fluchloralin flusilazole imibenconazole
myclobutanil myclobutanil nuarimol
oxycarboxin penconazole prochloraz
propiconazole pyrifenox tebuconazole
tetraconazole tolclofos-methyl triadimefon
triadimenol tridemorph triflumizole
Sui~abie herbicidal materials are:
2,4-D esters 2,4-DB esters acetochlor
aclonifen alachlor anilophos
benfluralin benfuresate bensulide
benzoylprop-ethyl bifenox bromoxynil
bromoxynil esters butachlor butamifos
butralin butylate carbetamide
chlornitrofen chlorpropham cinmethylin
clethodim clomazone clopyralid esters
CMPP esters cycloate cycloxydim
desmedipham dichlorprop esters diclofop-
methyldiethatyl
dimethachlor dinitramine ethalfluralin
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ethofumesate fenobucarb fenoxaprop ethyl
fluazifop fluazifop-P fluchloralin
flufenoxim flumetralin flumetralin
fluorodifen fluoroglycofen fluoroxypyr esters
ethyl
flurecol butyl flurochloralin haloxyfop
ethoxyethyl
haloxyfop-methyl ioxynil esters isopropalin
MCPA esters mecoprop-P esters metolachlor
monalide napropamide nitrofen
oxadiazon oxyfluorfen pendimethalin
phenisopham phenmedipham picloram esters
pretiiachlor profluralin propachlor
propanil propaquizafop pyridate
quizalofop-P triclopyr esters tridiphane
tril~iuralin
Par i_ularly suitable pesticidal materials are
chlor?yrifos and trifluralin.
The aqueous dispersion may include an addltional
pestlcidal material to that contained in the
microcapsules. This additional pesticidal material may
be present in solution, in the form of emulsion
partlcles, as a dispersion of a solid, or contained
wlthin microcapsules.
In a second aspect of the invention, there is
provided a storage-stable aqueous dispersion of a water-
insoluble material, wherein the water-insoluble material
is contalned within microcapsules having a volume median
par~icle size of not more than 6~m, preferably not more
than ~m, more preferably not more than 2~m, in the form
of a supersaturated solution or a supercooled melt,
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14
wherein the aqueous dispersion additionally comprises a
non-micellising surfactant to stabilise the dispersion,
and wherein the stabilised dispersion is substantially
free from micellising surfactant.
~ referred non-micellising surfactants are described
above.
The water-insoluble material (preferably a
pesticidal material as described above) preferably
constitutes at least 50% by weight of the aqueous
dispersion, and most preferably at least 70% by weight.
When in supersaturated solution (such as in xylene or any
other suitable solvent known in the art), the amount of
tne said material is preferably at least 70% by weight of
solution, most preferably at least 80% by weight of
solution.
The aqueous dispersion may include an additional
pesticide and/or an additional surfactant as described
above.
The aqueous dispersion may be provided in a closed
container.
In a third aspect of the invention there is provided
the use of a non-micellising surfactant (as described
above) to inhibit crystallisation of a water-insoluble
material from an aqueous dispersion containing the said
material, wherein the water-insoluble material is present
in the dispersion in the form of microcapsules containing
the said material as a supersaturated solution or a
supercooled melt.
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In a further aspect of the invention, there is
provided a method for the control or eradication of a
pest, which method comprises diluting an aqueous
dispersion as described above to a pesticidally-effective
concentration, and applying the resultant dispersion to
the pest or to a locus in which the pest is to be
cont-olled particularly, without any intervenin~ spray-
drying step.
As indicated above, the method o~ the invention is
particularly advantageous for the production of
microcapsules having a small particle size, for example
having a VMD of 6~m or less, particularly 2~m or less.
The chief advantage of such small capsules is that, as
the VMD decreases, it is possible to retain the majority
of the supercooled/supersaturated active in the liquid
form. It is thus possible to produce in a reliable
manner liquid core capsules ~ith the minimal use of
solvents, which in turn gives environmental advantages,
as well as a higher active loading in the final product.
~urther, such small capsules provide a higher surface
area to mass ratio than larger particles, and thus give
an enhanced release rate and better knock-down. Yet
another benefit of such small capsules is that they can
penetrate soil or surface grass thatch better than larger
capsules, and so are more efficacious in certain
applications where such soil or thatch mobility is
needed.
The presence of a liquid core in capsules made with
a supercooled molten active has several advantages, of
which the most significant from point of view of the
present invention is that the core does not crystallise,
thus causing rupture of the capsules, which can lead both
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16
to premature release, and to formulation instability on
storage. A second advantage is that a liquid core will
in general release its active more rapidly than will a
solid. This, combined with small particle size, gives a
significant increase in active release rate. A third
advantage of retaining the active in the liquid state is
that there is no possibility of producing a biologically
less active polymorph during crystallisation - a problem
which is addressed in another way in US-A-5160530
(Griffin).
Any water-insoluble solvent may be employed to
dissolve the water-insoluble material in the preparation
of tr.e microcapsules if a solvent is deemed desirable.
The use of such solvents reduces the tendency of the said
material to crystallise. Examples of typical solvents
are a~omatic solvents, particularly alkyl substituted
be~.zenes such as xylene or propyl benzene fractions, and
mixed naphthalene and alkyl naphthalene fractions;
mineral oils; kerosene, dialkyl amides of fatty acids,
particularly the dimethyl amides of fatty acids such as
the dimethyl amide of caprylic acid; chlorinated
aliphatic and aromatic hydrocarbons such as 1,1,1-
trichloroethane and chlorobenzene, esters of glycol
derivatives, such as the acetate of the n-butyl, ethyl,
or methyl ether of diethyleneglycol, the acetate of the
methyl ether of dipropyleneglycol, ketones such as
isophorone and trimethylcyclohexanone tdihydroisophorone)
and the acetate products such as hexyl, or heptylacetate.
The preferred organic liquids are xylene, propyl benzene
fractions, alkyl acetates, and alkyl naphthalene
fract~ons.
SUBSTITUT~ SHEET (RU~E 26
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17
.~aterlals may be employed which are normally solid
at amblent temperatures, but which are capable of forming
eutectic mixtures with the water-insoluble material. The
use of such materials will generally reduce the tendency
of the water-insoluble material to crystallise.
A further advantage of the encapsulation method in
accordance with the invention is that it permits the
production of aqueous compositions containing two or more
active materia~s, where the materials are such that
direct formulation of the materials (i.e., without
encapsulation of one or both of them) would lead to a
product which is chemically or physically unstable. In
one aspect, the said actives may be separately
encapsulated, but in an alternative and preferred
embodiment, one or mor~ of the active materials (or some
portion of a single active material) may be encapsulated
by the method in accordance with the invention, and the
balance not encapsulated, for example, simply dispersed
in the aqueous phase. In this way, the un-encapsulated
active material is immediately biologically available
upon application, whereas the encapsulated material is
released more slowly. The amount of each material
employed in such different forms will vary dependent upon
the particular application but in general terms, each
such material may constitute from 0.1 to 99.9~ by weight
of the total of the encapsulated material.
Compositions of the invention may also include a
stabiliser of the kind disclosed in WO95/07614.
Other conventional additives may also be
incorporated into the formulation such as emulsifiers,
dispersants, and film-forming polymers (provided that
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18
such additives do not form micelles under storage
conditions).
A number of preferred embodiments of the invention
are described in the following Examples.
The following materials were used in the Examples:
Trade Name Nature of Material
Atlox 4913 nonionic surfactant
Solvesso 200 aromatic solvent
Sopro~an T-36 anionic copolymer
Voranate M-220 isocyanate
Voranate M-229 isocyanate
PAPI 135 isocyanate
Hyvis 30 poly~iso butylene)
~yvis 04 poly(iso butylene)
Goherseran L-3266 anionically modified PVA
~orwe~ EFW anionic surfactant blend
Gohsenol GH20 PVA 88% hydrolysed, high MW
Gohsenol GL05 PVA 88% hydrolysed,
intermediate MW
Gohsenol GL03 PVA 88% hydrolysed, low MW
Example l: Molten chlorpyrifos at 50~C (615g) was
mixed with PAPI 135 (30g) and emulsified into 460g water
containing lOg Gohsenol GH20 (an aqueous PVA solution)
and lOg Gohsenol GL05 (an aqueous PVA solution) at 50~C.
An emulsion of about 2~m vmd was produced. To this was
added a solution of diethylenetriamine (lOg), Atlox 4913
(20g) ln water (70g) to produce an encapsulated product
containing a~out 600g/l chlorpyrifos. This product
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19
showed no significant crystallisation after 2 weeks
storage. A comparative example made by emulsification of
the same quantity of chlorpyrifos into the same
surfactant solution but without encapsulation,
crystallised on standing overnight at laboratory
temperature.
Example 2: Molten trifluralin at 50~C (615g) was
mixed with PAPI 135 (30g) and emulsified into 365g water
containing lOg Gohsenol GH20 and lOg Gohsenol GL05 at
50~C. An emulsion of about 3~m vmd was produced. To
this was added a solution of diethylenetriamine (lOg~,
Atlox 4913 (20g) in water (70g) to produce an
encapsulated product containing about 600g/l trifluralin.
This product showed no significant crystallisation after
2 weeks storage. A comparative example made by
emulsificatlon of the same quantity of trifluralin into
the same surractant solution crystallised on standing
overnight at laboratory temperature.
Example 3: The composition of Example 2 was repeated
but emulsified at about 1.5~m and diluted to 500g/l.
This product also showed no significant crystallisation
after 2 weeks storage.
~xample 4: Molten chlorpyrifos at 50~C (615g) was
mixed with PAPI 135 (30g) and emulsified into 440g water
containing lOg Gohsenol GH20 and lOg Gohsenol GL05 at
50~C. An emulsion of about 2.5~m vmd was produced. To
this was added a solution of diethylenetriamine (lOg),
Atlox 4913 (20g) in water ~70g~ to produce an
encapsulated product containing about 600g/l chlorpyrifos
with a particle size of about 1.29~m. This product
SUBSTITU~ SHEET (RUL~ 26)
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showed no signlficant crystallisation after 2 weeks
s~orage.
Example 5: Molten chlorpyrifos at 50~C (615g) was
mixed with PAPI 135 (30g) and dioctyl phthalate (50g) and
emulsified into 380g water containing lOg Gohsenol GH20
and lOg Gohsenol GL 0 5 at 50~C. An emulsion of about
1.4~m vmd was produced. To this was added a solution of
diethylenetriamine (lOg), Atlox 4913 (20g) in water (70g)
to produce an encapsulated product containing about
~OOg/1 chlorpyrifos with a particle size of about 1.38~m.
This product showed no significant crystallisation after
2 wee~s storage.
Exam~le 5: Molten chlorpyrifos at 55~C (462g) was mixed
with Voronate M-220 (32g) and emulsified i~to 400g water
containing 40g Poval 203 (PVA 88~ hydrolysed supplied by
Kuraray) at 50~C. An emulsion of about 1.84~m vmd was
produced. To this was added a solution of
diethylenetriamine (8g) in water (98g) to produce an
encapsulated product containing about 46% w/w
chlorpyrifos. This product showed no significant
crystallisation after 2 weeks storage.
Example 7: Molten chlorpyrifos at 45~C (615g) was
mixed with PAPI 135 (lOg) and emulsified into 440g water
containing lOg Gohsenol GH20 and lOg Gohsenol GL05 at
45~C. An emulsion of about 1.4~ vmd was produced. To
this was added a solution of diethylenetriamine (3.5g),
Atlox 4913 (20g) in water (70g) to produce an
encapsulated product containing about 600g/1 chlorpyrifos
with a particle size of about 1.4~m. This product showed
no significant crystallisation after 2 weeks storage.
SUBS~ SltEET (RULE 26)
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ExzmDie 8: Molten chlorpyrifos at 45~C (615g) was
mixed with PAPI 135 (20g) and emulsified into 440g water
containing lOg Gohsenol GH20 and lOg Gohsenol GL05 at
45~C. An emulsion of about 1.4~m vmd was produced. To
this was added a solution of diethylenetriamine (7g~,
Atlsx 4913 (ZOg) in water (79g) to produce an
encapsulated product containing about 600g/l chlorpyrifos
with a particle size of about 1.4~m. This product showed
no significant crystallisation after 2 weeks storage.
~xam?'e 9: Molten chlorpyrifos at 95~C (615g) was
ml~e~ wl h PAPI 135 (lOg) and emulsified into 440g wate-
con,-_n~ng lOg Gohsenol GH20 and lOg Gohsenol GL05 at
45~~. An emulsion of about 1.4~m vmd was produced. To
this was added a solution of tetraethylenepentamine (3g),
At'~x 4913 (20g) in water (70g) to produce an
enca_su'ated product containing about 600g/l chlorpyrifos
wi -. ~ particle size of about 1.4~m. This product showed
no s-~n~fican~ crystallisation after 2 weeks storage.
Example 10: Molten chlorpyrifos (615g) at 50~C was
mixed with PAPI 135 (20g) and Solvesso 200 (200g) and
emu s fied into 390g water containing 20g Atlox 4991 at
50~C. An emulsion of about 1.5~m vmd was produced. To
thls was added a solution of diethylenetriamine (7g),
A. ox 4913 (20g) in water (130g) to produce an
encapsulated product containing about 45~ w/w
chlorpyrifos with a particle size of about l.~m. This
product showed no significant crystallisation after 2
weeks storage. A comparative example made by
emu'slf1cation of the same quantity of chlorpyrifos and
Solvesso 200 into the same surfactant solution but
wi,:~o~t encapsulation crystallised on storage at
laDo~atory temperature.
SUBSTITUT~ SHEE~ (RULE 26)
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Example 11: Molten chlorpyrifos at 45~C (615g) was
mixed with PAPI 135 (30g) and emulsified into 430g water
containing 20g of a 10,000 mol wt 88% hydrolysed
polyvinyl alcohol (PVA) and 20g Atlox 4913 at 45~C. An
emulsion of about 1.65~m vmd was produced. To this was
added a solution of diethylenetriamine ~10g) in water
(70g) to produce an encapsulated product containing about
600g/l chlorpyrifos with a particle size of about 1.63~m.
This product showed no significant crystallisation after
4 weeks storage.
Example 12: Molten trifluralin at 50~C (462g) was
mixed with PAPI 135 (7.4g) and emulsified into 430g water
containing 60g polystyrene sulphonate (Sodium salt) a.
5C~C. .~n emulsion of about 6~m vmd was produced. To
th s was added a solution of diethylenetriamine (2.5g) in
warer (lOOg) to produce an encapsulated product
conta ning about 45% w/w trifluralin. This product
sr.owed no slgnificant crystailisation after 2 weeks
storage. A comparative example made by emulsification of
the same quantity of trifluralin into the same surfactant
solution crystallised on standing overnight at laboratory
temperature.
Example 13: Molten trifluralin at 50~C (515g) was
mixed with PAPI 135 (8.2g) and emulsified into 380g water
containing 67g polystyrene sulphonate (Sodium salt) at
50~C. An emulsion of about 9~m vmd was produced. To
this was added a solution of diethylenetriamine (2.7g) in
water (lOOg) to produce an encapsulated product
containing about 45% w/w trifluralin. This product
showed no significant crystallisation after 2 weeks
storage. A comparative example made by emulsification of
SUBSrITUT~ SHEET (RULE 26)
CA 0226l034 l999-0l-l8
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the same quantity of trlfluralln into the same surfactant
solution crystallised on standing overnight at laboratory
temperature.
S ExamPle 14: Molten chlorpyrifos at 50~C (615g) was mixed
with PAPI 135 (lOg) and emulsified into 450g water
containing 80g polystyrene sulphonate (Sodium salt) at
50~C. An emulsion of about 4.2~m vmd was produced. To
this was added a solution of diethylenetriamine (2.7g) in
wate~ (lOOg) to produce an encapsulated product
containing about 50~w/w chloripyrifos. This product
showed no significant crystallisation after 2 weeks
storage.
ExamPle 15. Molten chloripyrifos at 50~C (615g) was mixed
with PAPI 135 (lOg) and emulsified into 450g water
containing 125g PVP K-30 at 50~C. An emulsion of about
1.49~ vmd was produced. To ~his was added a solution of
diethylenetriamine (2.7g) in water (lOOg) to produce an
enca~sulated product containing about 50~w/w
chlorpyrifos. This product showed no significant
crystallisation after 2 weeks storage.
Exam~le 16. Molten chlorpyrifos at 50~C (615g) was mixed
with PAPI 135 (lOg) and Hyvis 30 (30g) and emulsified
into 450g water containing lOOg Sopropon T-36 at 50~C.
An emulsion of a~out 1.2~m vmd was produced. To this was
added a solution of diethylenetriamine (2.5g) in water
(lOOg) to produce an encapsulated product containing
about 50~w/w chlorpyrifos. This product showed no
significant crystallisation after 2 weeks storage.
Example 17. Molten chlorpyrifos at 50~C was mixed with
Voronate M-220 (20g) and emulsified into 550g water
YJBS~lTUTE SHEE~ (RULE 2S)
.
CA 0226l034 1999-0l-l8
W098/03065 PCT/GB97/01951
24
containing 100g Sopropon T-36 at 50~C. An emulsion of
about 1.8~m vmd was produced. To this was added a
solution of diethylenetriamine ~5g) in water (lOOg) to
produce an encapsulated product containing about 47~w/w
chlorpyrifos. This product showed no significant
crystallisation after 2 weeks storage.
Example 18. Molten chlorpyrifos at 50~C (615g) was mixed
with Voronate M-220 (30g) and emulsified into 400g water
containing 40g Gohsenol GL03 at 50~C. An emulsion of
about 1.84~m was produced. To this was added a solution
of diethylenetriamine (lOg) in water (120g) to produce an
encapsulated product containing about 51.5~wiw
chlorpyrifos. This product showed no significant
crystallisation after 2 weeks storage.
Exam~le 19 Molten chlorpyrifos at 50~C (615g) was mixed
with Voronate M-220 (lOg) and emulsified into 300g water
containing 20g Gohsenol GLO3 and Morwet EFW (5g) and
50~C. ~n emulsion of about 1.7~m vmd was produced. To
this was added a solution of diethylenetriamine (3g) in
water (250g) to produce an encapsulated product
containing about 51~w/w chlorpyrifos. This product
showed no significant crystallisation after 2 weeks
storage.
ExamDle 20 Chlorpyrifos-methyl (42g) was dissolved in
methyl oleate (20g) at 35~C and then added to 3g Voronate
M-229. This oil phase was emulsified into 40g of water
containing 4g Gohsenol GL03 at about 35~C to produce an
emulsion of about 2.4~m vmd. To this was added lg
diethylenetriamine in 10g water to produce an
encapsulated product containing about 35% chlorpyrifos-
methyl (about 53~ encapsulated oil).
SUBSrl~UT~ SltEE~ (RULE 26)
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ExamPle 21 Chlorpyrifos-methyl was dissolved in Solvesso
200 (ZOg) at 35~C and then added to 3g Voronate M-229.
This oil phase was emulsified into 40g of water
containing 4g Gohsenol GL03 at about 35~C to produce an
emulsion of about l.9~m. To this was added lg
diethylenetriamine in lOg water to produce an
encapsulated product containing about 35~ chlorpyrifos-
methyl (about 53~ encapsulated oil).
ExamPle 22 Chlorpyrifos-methyl (42g) was dissolved in
Solvesso 200 (20g) and Hyvis 30 (3g) at 35~C and then
added to 3g Voronate M-229. This oil phase was
emulsified into 40g of water containing 4g Gohsenol GLO3
at about 35~C to produce an emulsion of about 2.25~m vmd.
To this was added lg diethylenetriamine in lOg water to
produce an encapsulated product containing about 34
chlorpyrifos-methyl (about 55~ encapsulated oil).
ExamPle 23 Chlorpyrifos-methyl (42g) was dissolved in
Solvesso 200 (20g) at 35~C and then added to lg Voronate
M-229. This oil phase was emulsified into 40g of water
containing 4g Gohsenol GLO3 at about 35~C to produce an
emulsion of about 2.98~m vmd. To this was added 0.33g
diethylenetriamine in lOg water to produce an
encapsulated product con~aining about 35~ chlorpyrifos-
methyl (about 53~ encapsulated oil).
Example 24 Chlorpyrifos-methyl (42g) was dissolved in
Solvesso 200 (20g) at 3S~C and then added to lg Voronate
M-229. This oil phase was emulsified into 40g of water
containing 8g Gohsenol GLO3 at about 35~C to produce an
emulsion of about 0.69~m vmd. To this was added 0.33g
dlethylenetriamine in lOg water to produce an
SUBSTITUI~ SHEET (RULE 26)
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CA 0226l034 1999-0l-l8
W098/03065 PCT/Gs97/01951
26
encapsulated product containing about 35% chlorpyrifos-
methyl (about 55~ encapsulated oil).
ExamPle 25 Chlorpyrifos-methyl (42g) was dissolved in
Solvesso 200 (20g) at 35~C and then added to lg Voronate
M-229. This oil phase was emulsified into 40g of water
containing 6g Gohsenol GL03 at about 35~C to produce an
emulsion of about 1.38~m vmd. To this was added 0.33g
diethylenetriamine in lOg water to produce an
encapsulated product containing about 35~ chlorpyrifos-
methyl (about 55~ encapsulated oil).
Samples from examples 20-25 all stored for 2 weeks at -
5~C showed no crystallisation whereas emulsions prepared
from the same oil and aqueous phases showed
crystallisation typical of supersaturated oil phases.
Exam~le 26 Chlorpyrifos (300g) and Lindane (120g) were
dissolved in Trimethylcyclohexanone and Solvesso 100.
57g CL this oil phase was mixed with PAPI 135 (20g).
This was emulsified into 300g water containing Anonaid HF
(lOg) and Atlox 4991 (20g) to produce an emulsion of
abou~ 0.62~m vmd. To this was added 7g
diethylenetriamine and 30g Atlox 4913 in 150g water to
produce a product containing 300g/1 chlorpyrifos and
120g/1 Lindane. This product was stored at -5~C for 1
week and then tested by dilution into cold water (5~C)
and being passed through a 45~m sieve. No crystals were
observed. A parallel study with an emulsion prepared by
the same route resulted in gross crystallisation of both
chlorpyrifos and Lindane in the same time period.
Exam~le 27 Molten chlorpyrifos (480g) was mixed with
Voronate M-220 (25g), Solvesso 200 (107g) and Hyvis 04
SUBS~I~UT~ SHEE~ (RULE 26)
CA 02261034 1999-01-18
W09810306S PCT/GB97/01951
27
(25g) and emulsified into 400g water containing 50g
Gohsenol GL03. An emulsion of about 1.64~m vmd was
produced. To this was added a solution of
diethylenetriamine (18g) and propylene glycol (40g) in
water (lOOg total) to produce an encapsulated product
containing about 480g/1 chlorpyrifos. This product
showed no significant crystallisation after 2 weeks
storage.
ExamPle 28 Molten chlorpyrifos (480g) was mixed with
Voronate M-220 (25g), Solvesso 200 (107g) and Hyvis 04
(25g) and emulsified into 400g water containing 45g
Gohsenol GL03 and 30g Gohseran L-3266. An emulsion of
about 0.82~m vmd was produced. To this was added a
solution of diethylenetriamine (18g) and propylene glycol
(40g) in water (lOOg total) to produce an encapsulated
product containing about 480g/1 chlorpyrifos. This
product showed no significant crystallisation after 2
weeks storage.
ExamDle 29 Trifluralin (55.9g) and ethalfluralin (11.3g)
as a eutetic mixture were melted at 40~C and 7.5g of
methylene diisocyanate was added thereto. This oil phase
was added to water (60g) containing sodium polyacrylate
(1.5g) at 40~C with high shear. An emulsion was produced
of approximately 5~m vmd. To this was added
diethylenetriamine (5g) in water (8.5g). The mixture was
stirred at 40~C for thirty minutes. The capsules
produced were storage stable.
SUBSTITUTE SHEET (RULE 26)
