Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02198704 2006-11-20
Sprayable, film-forming system releasing active substances
for use on plants
SPECIFICATION
The present invention relates to a sprayable, film-forming prepara-
tion, in particular for the systemic administration of biologically
active substances to plant organisms.
Active substance formulations normally used for plants in practice
are emulsion concentrates, suspension concentrates, or so-called
wettable powders which are applied by means of different spray-
ers, spargers, or nebulizing devices (e.g. spray bottles). However,
these conventional preparations entail the disadvantage that active
substance losses occurring during their application contribute to
the contamination of the environmental sections (air, earth, wa-
ter). This problem is caused by the spray flowing or dripping down
the plant surfaces, by rain water washing the spray off, and by
the spray drift during application. Their insufficient retention
(adherence) and the poor wettability of plant surfaces are further
disadvantages of these active substance formulations. These defi-
ciencies frequently interfere with achieving the desired effect.
In the past, many attempts were made to minimize these draw-
backs in order to optimize the use of spray agents:' According to
the art, these attempts can be summarized as follows:
1. Application properties of sprays are improved by adding dif-
ferent substances, such as surface-active agents, substances
to prevent drying up, re-humidifying agents, hygroscopic addi-
tives, foamers, and in particular adhesion promoters.
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2. Selective positioning to plant surfaces is considerably facili-
tated by loading the spray electrostatically.
3. The retention and wetting properties can be improved by
modifying the size of droplets, the spraying pressure, and the
spraying distance.
However, none of these measures provide a satisfactory solution
with respect to spray drift and environmental impact.
In order to overcome this disadvantage, improved active sub-
stance release systems were developed which represent an alter-
native to conventional sprays. These are depot formulations in the
form of flat-shaped, patch-like, adherent or pressure-sensitive ad-
hesive systems which are applied to the plant's shoot axis. These
administration forms for active substances effectively overcome
the problem of active substance losses and the resulting environ-
mental pollution; however, their use involves a lot of other prob-
lems mainly caused by their application. With this kind of devices
it is extremely important to dimension the size of their contact
surface to the plant such that it does not project any parts of the
plant. In case of plants the growth of which limits the choices of
application site, e.g. those completely covering the soil, their ap-
plication is therefore very difficult. Also, the application of these
systems to plants whose surfaces have spines or thorns must be
regarded as critical.
In addition, there are problems with respect to using these sys-
tems in plants excessively growing in thickness; if the carrier foil
is insufficiently stretchable, the application around the stems in-
volves the risk that the plant becomes strangled or that the sys-
tem grows into the shoot axis, this may damage the underlying
tissue layers.
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Finally, the use of such systems takes a relatively great deal of
time and work not only with respect to the application, but also
afterwards since they must be removed when the treatment is
completed. Moreover, there is the cost-increasing problem of
waste disposal.
According to this state of the art one can say in general terms that
it has provided considerable progress with respect to the reduction
of the required active substance expenditure, the frequency of
application, and the undesired effects on other organisms, but that
this is accomplished at the expense of other properties.
Film-forming formulations represent another kind of active sub-
stance release systems. These are known in the art from the fol-
lowing patents SU 1364267, DE 2804563, JP 66009674, and US
4923698.
The publication SU 1364267 relates to a film-forming formulation
based on carboxymethylcellulose and used in the storage of agri-
cultural products, in particular in the preservation of fruits and
vegetables. To this end, the crop product to be stored is treated
by spraying or dipping to form a thin film on the surface of the
plant organs; owing to its physical properties, this film protects
the plants from unnecessary losses of water and therefore im-
proves their storage life. However, there is no indication in this
publication that this preparation contains active substances.
German patent DE 2804563 discloses an active substance-con-
taining, film-forming preparation. It describes a formulation that
comprises bird repellents and is used as an agent against bud
feeding in useful and flowering shrubs. This is an aqueous poly-
mer dispersion that is stirred into water together with the active
substance during the preparation of the plant spray; but it can also
be formulated as an active substance-containing wettable powder.
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In both cases the incorporated base polymers, such as homopoly-
mers and copolymers of vinyl acetate or acrylic ester, serve as
adhesives.
Japanese patent publication JP 6445100 describes another active
substance-containing, film-forming formulation. This is a prepara-
tion of rodent repellents based on an inorganic active substance
absorber (e.g., kaolin, talc). The addition of polymeric adhesion pramters
such as methyl or carboxymethylcellulose, polyvinyl alcohol, or
urea, results in the formation of a water-insoluble film layer adher-
ing to the plants' surfaces and providing protection against ro-
dents owing to its content of repellents.
US 4923698 relates to film-forming, nonpolymeric preparations of
insecticides or insect repellents. In this case a formulation based
on a water-in-oil emulsion is proposed which comprises lubricants
in addition to the bioactive substances. These lubricants ensure
that the film formed by evaporation of the predominant portion of
the oil and water phase has a property rendering the movement of
running insects on its surface impossible. In addition, the active
substances contained in the film can considerably increase the
outcome of pest control because of their direct influence on pests.
In connection with film-forming, sprayable active substance prepa-
rations it is finally referred to the articles in the technical journals
Hort science (20,50 : 879-881 ) and Plant Disease (67 : 212-214),
which describe the experimental use of such developments in
plants to control leaf diseases.
These known active substance-containing sprayable formulations
which are capable of forming films have the severe disadvantage
in common that the films resulting after their application cover the
plant surface only for a relatively short time; this is to be ascribed
to their hydrophilic character. These formulations are not suitable
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for the systemic release of active substances to the plant organ-
ism because they lack the capability of adhering permanently. The
active substances must be present on the plant surface for a suf-
ficiently long time in order to supply the plant organism with the
active substance in a concentration sufficient to develop persistent
systemic action.
Moreover, it is not the main function of these formulations to ad-
minister active substances to the plant, but to provide an external
protection of the plant against pests. For this reason the known
application systems do not offer a satisfactory solution of the
above-mentioned problem with respect to the administration of
biologically active substances to plant organisms.
Thus, the horticultural wish for ecologically beneficial active sub-
stance depot preparations for plants which are easy to handle is
still left open by the art.
It is the object of the present invention to propose a sprayable,
active substance-containing, film-forming, pressure-sensitive ad-
hesive, water-insoluble, and at least partially biodegradable prepa-
ration that preferably does not pollute the environment and which
provides active substance release systems combining the advan-
tages of conventional spraying systems and those of the so-called
controlled-release-formulations without having to accept their
drawbacks.
Most surprisingly, this object is achieved with an active substance
formulation according to the characterizing features of the main
claim; this fully meets the above-mentioned requirements. Addi-
tional essential embodiments of the active substance formulation
are provided in the subclaims.
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The term "sprayable, film-forming preparation/formulation" is used
to mean preparations which form a film on the surface of a sub-
strate after application on said substrate by means of spraying.
The film's state of distribution may differ; it may be a con-
tinuous film, or a discrete film distributed in lumps, and also inter-
mediary transient stages.
Films made of the active substance formulations according to the
present invention advantageously are pressure-sensitive adhesive,
insoluble in water, and at least partially biodegradable.
Polymers performing both the function of film formers and that of
active substance carriers are essential components of formulations
according to the present invention. Such film-forming, sprayable
polymer solutions are known from human medicine. They are used
as wound dressings instead of textile dressing materials and ad-
hesive dressings and are called "spray plaster" in colloquial lan-
guage.
Homopolymers or copolymers of esters of acrylic acid and/or
methacrylic acid, e.g., methyl acrylate, ethyl acrylate, acrylic acid-
n-butyl-ester, and methacrylic methyl ester, are used as film-
forming substances for the production of formulations according
to the present invention. Moreover, other suitable polymers are
ethylcellulose, cellulose butyrate or cellulose acetate, as well as
polyhydroxy butyrate and polyhydroxy valerate.
The preparations according to the present invention are physical
active substance/polymer-combinations which are present as solu-
tion or emulsion. They are sprayed on a plant surface as aerosols
and form thin, coherent, active substance-containing, and water-
insoluble films after evaporation of the solvents or emulsifiers.
The nontoxic organic solvents contained in these preparations are
highly volatile. In general, they have a boiling range of +50°C to
180°C. If possible, their boiling point should not exceed 150°C
to
prevent unnecessarily long drying periods of the formed film. Suit-
able solvents include ethyl acetate, chloroform, acetone, ethanol,
or their mixtures. The amount of the solvent or solvent mixture
must be chosen such that the total preparation has a relatively low
viscosity ensuring perfect spraying without formation of ropes.
In addition, the preparations according to the present invention
must be perfectly aerosolizable and stable during storage in aero-
sol containers. Suitable propellants include light hydrocarbons,
such as propane, butane, isobutane, and their mixtures in the form
of a liquefiable gas. The halogenated hydrocarbons frequently
used as propellant in the past shall not be used any longer
because of their high ozone-destructive potential. Nitrogen, carbon
dioxide, or dinitrogen monoxide may be used as blowing gases
instead of light hydrocarbons.
The total amount of the solids mixture used as film former and
active substance carrier system shall amount to 0.5 to 10~-wt.,
preferably 4 to 6~-wt., relative to the total preparation in-__.~~
cluding propellant.
An important advantage of the active substance formulation ac-
cording to the present invention is the fact that the formed films
are pressure-sensitive adhesive. This efficiently counteracts the
serious disadvantage of conventional techniques, i.e., the insuffi-
cient retention. The active substance-containing films resulting
from these formulations preferably exhibit permanent adhesive-
ness. They immediately and permanently adhere to plant surfaces
and thus ensure intimate contact to the terminal tissue of the
plant; this contact is absolutely necessary for an optimum active
substance release. In particular if a long-term, sustained active
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substance supply is required, this property gains special impor-
tance. The high adhesive capacity is relatively temperature-inde-
pendent in the application area. The stability of the films is also
ensured in this area. For this reason, they are suitable both for the
application to plants in the interior and for outdoor uses.
The pressure-sensitive adhesive properties of the film bring about
additional advantages with respect to application, in particular in
plant protection. Owing to the immediate adhesive power these
films may serve as mechanical barrier or trap for numerous de-
structive insects which adhere to the film surface at the slightest
touch. Since the films comprise active substances pests (e.g.,
fungus spores or insects) immediately come into contact with the
active substance so that a harmful action is prevented.
Pressure-sensitive adhesive properties may be achieved by using
suitable polymers as active substance carrier. These mainly include
mixed copolymers of acrylic acid and acrylic esters, in particular
alkyl acrylate having 4 to 12 carbon atoms in the alkyl group, for
example, 2-ethylhexyl acrylate, n-butyl acrylate, and isooctyl
acrylate.
If polymers are used which are not pressure-sensitive adhesive,
suitable auxiliaries must be added to obtain the desired properties.
Resin-like substances, such as modified natural resins, above all
colophony and its derivatives, polyterpene resins, hydrocarbon
resins, and coumarone-indene resins mainly serve this purpose.
Particularly suitable are colophony esters (such as Fora~~ 85 and
Staybelite~Fster 10) since these are excellently compatible with
polyacrylates. The amount of resin to be added depends on the
desired adhesive properties and has an upper limit because the
cohesion of the formed films is too low where the resin proportion
is excessively high. The amount may vary fxom 1.0 to 20~-wt.,
normally
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it is of the order of 5 to 10%-wt., relative to the solids content of
the preparation.
Another advantage of the preparations according to the present
invention lies in the fact that the formed films are insoluble in wa-
ter. This is of particular importance because the films adhere to
the plant surfaces even during high-rainfall periods. For this reason
the adhesive strength of the films does not change over a desired
treatment period.
The water resistance results from hydrophobic properties of the
film-forming substance. In addition to polyacrylates, polyhydroxy
butyrate and hydroxy butyrate-hydroxyvalerate-copolymers, as
well as ethylcellulose and cellulose butyrate and cellulose acetate
may be used as suitable film-forming components of the prepara-
tions according to the present invention. Moreover, they stand out
for biodegradability, rendering them particularly suitable for use in
the production of the preparations according to the present inven-
tion.
Films formed on plant surfaces from preparations according to the
present invention must preferably be biodegradable. This means
that they are partially or completely decomposed by the action of
a biologically active environment (microorganisms). This property
is particularly advantageous since the films, owing to their good
pressure-sensitive adhesiveness, may remain on the plants as ac-
tive substance depots for longer periods of time (e.g., one vegeta-
tion period) without having to be removed later. The degree of
biodegradability can be controlled by the choice of polymer. The
user of these formulations can therefore save a great deal of time
and work and simultaneously has the advantage of a persistent
active substance supply. This combination of the above-mentioned
properties renders the preparations according to the present
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invention clearly superior to active substance release systems de-
scribed in the art.
The active substances contained in the films according to the
present invention are released in a controlled manner, the release
taking place by diffusion.
Active substances which can be released to plants by means of
the preparations according to the present invention are those in-
fluencing processes in the animal or plant organism. Insecticides,
fungicides, acaricides, bactericides, and growth regulators are to
be mentioned as systemically active plant protection agents in the
first place.
Systemic insecticides include, for example, butocaroxim, di-
methoate, fenoxycarb, methamyl, oxamyl, oxydemeton-methyl,
pirimicarb, or propoxur.
Systemic fungicides include, for example, benomyl, bromucona-
zole, bitertanole, etaconazole, flusilazol, furalaxyl, fosetyl-Al,
imazalil, metalaxyl, penconazole, propiconazole, thiabendazol,
triadimefon, triadimenol, or triforine.
Systemic acaricides include, for example, clofentizine, fenbutatin
oxide, and hexythiazox.
Systemic growth regulators include, for example, ethephon and j3-
indolylacetic acid (IAA).
Flumequine, for example, is to be mentioned among the systemic
bactericides.
Moreover, the preparations according to the present invention may
comprise active substances which do not act systemically in the
2198704
plant but remain on the plant surface and therefore have a contact
action on pests. It is possible, for example, to incorporate contact
fungicides belonging to the family of dithiocarbamates, such as
maneb, zineb, or mancozeb, into the preparations according to the
present invention in order to protect plant surfaces from local
fungus infections (fungi causing false mildew, organisms causing spot-
ting on leaves, various rust diseases).
Bird and insect repellents represent another application example of
bioactive substances which do not develop their action via the
plant. These may also be applied on plant surfaces by means of
the preparations according to the present invention and can thus
develop their action on the respective pest.
Active substances may be present in preparations according to the
invention either individually or in a mixture. They may be dissolved
or dispersed in the polymer matrix. A preferred embodiment of
formulations according to the present invention has the following
ingredients:
a) 1.0 to 10.0%-wt. of solids, the solids comprising
0.5 to 8.0%-wt. of at least one polymer
0.5 to 5.0 of at least one active substance
0.0 to 2.0%-wt. of formulation auxiliaries,
relative to the total weight of the preparation,
b) 0.5 to 80%-wt. of at least one volatile organic solvent
c) 0.5 to 80%-wt. of at least one liquefied gas propellant.
Preparations according to the present invention may comprise as
auxiliary agents penetration enhancers, tackifiers, emulsifiers, and
plasticizers. The function of these auxiliary agents is, on the one
hand, to offer the active substance to the plant in a suitable
CA 02198704 2006-03-06
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physical-chemical form and, on the other hand, to produce the optimum effect
of the
potency inherent in an active substance
Penetration enhancers intensify the diffusion of a bioactive substance into
the
conducting system of the plant. For this purpose, the following substances may
be
added: alkylsulfates, alkyl sulfonates, fatty acids, fatty acid salts of
multivalent
metals, fatty acid esters, amine oxides, mono-, di- or triglycerides, long-
chain
alcohols, salicylic acid, 2-pyrrolidone derivatives, or urea.
Adhesive resins are suitable tackifiers. Colophony esters (Staybelite ~ Ester
10) and
synthetic hydrocarbons (such as Escorez~ 1102 F) are particularly suitable.
Suitable emulsifiers include, for example, higher fatty alcohols, partial
fatty acid
esters, polyvalent alcohols, partial fatty acid esters of sugars,
polyethyleneglycol fatty
acid esters, polyethyleneglycol sorbitan-fatty acid esters, as well as
phospholipides,
quaternary ammonium compounds, and pyridinium compounds.
Suitable plasticizers include low-molecular polyethylene alcohols, glycerol
esters,
mono- and polyvalent alcohols, fats, or waxes.
The formulations according to the present invention may serve to administer
bioactive substances to plants, which have both a systemic and a local action.
Plant
protection is a preferred field of application of the preparations according
to the
present invention. In an embodiment of the present invention, the formulations
of the
present invention can be used as a protective film covering plant surfaces for
prevention of fungus infections, and/or suction and voracity by pests. The
following
examples are given to illustrate the present invention. Any indications as to
quantities, proportions, and percentages relate to the total weight of the
preparation
(including propellant), unless otherwise stated.
21504180.2
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Example 1:
4.5 parts by weight of a 2-ethylhexyl acrylate/acrylic acid-copoly-
mer having a molar mass of 750,000 dalton are dissolved in a
pressure vessel under heating and stirring in 44 parts by weight of
ethyl acetate. After addition of 0.9 parts by weight of colophony
resin (Fora1~85) used as tackifier, 0.6 parts by weight of the active
substance triticonazole are dispersed in the mass thus obtained.
This active substance-containing polymer solution, whose relative
viscosity at 25°C amounts to 0.58 Pa.s (according to Brookfield
LVF/measuring body), can be filled into an aerosol container under
addition of 50 parts by weight of same portions of butane, pro-
pane, and isobutane.
Example 2:
parts by weight of the active substance fenarimole together
with 0.5 parts by weight of N-methyl-2-pyrrolidone are added
to 29.5 parts by weight of a conventionally obtained mixed polymer
consisting of 75%-wt. of poly-2-ethylhexyl acrylate, 15%-wt. of
polyacrylic acid, and 10%-wt. of polymethyl methacrylate, and
which is present as a 48%-wt.-polymer solution in a solvent
mixture consisting of equal parts by weight of ethyl acetate
and ethanol. The added active substance is homogeneously
distributed in the mass under constant stirring. After addition of
65 weight percentage of liquefied butane, the active substance-
containing polymer solution is filled into an aerosol container.
