Note: Descriptions are shown in the official language in which they were submitted.
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ANTI-CAKING COMPOSITIONS FOR FERTILIZERS
Field of the Invention
The present invention relates to compositions used for
preventing caking and crust formation in several types of
manures or fertilizers in the form of granular solids.
State of the Art
At least two general types of fertilizers in the form of
granular solids are currently used:
1) so-called simple fertilizers, among which the most used
are different potassium, phosphorus or nitrogen compounds
assimilable by plants, for example, potassium chloride (KC1),
ammonium (AN), potassium (KN) and calcium (CN) nitrates, mono-
and diammonium sulfates and urea-based fertilizers;
2) complex fertilizers based on their overall content of
nitrogen, phosphorus and potassium, which are usually called
NPK, and which are different from one another mainly due to
their nitrogen, phosphorus and potassium content, expressed as
the percentage of nitrogen (N), phosphoric anhydride (P205) and
potassium oxide (K20) which the complex fertilizer contains.
Most of these fertilizers, which when recently
manufactured have the appearance of granular masses with good
flowability and homogeneity, due to the nature of the salts
which they contain, show a clear tendency for caking (a
phenomenon consisting of the coalescence of fertilizer particles
or granules, forming masses that are more or less difficult to
separate), which increases insofar as the storage and transport
conditions thereof involve their exposure to relatively high
temperature, humidity and pressure conditions. The caking and
crust formation of fertilizers causes serious problems at the
time of their dosing and application.
Another frequent problem observed during the formation of
fertilizers in granular form is the formation of dust,
fertilizer particles that are fine enough to become dust
transported by the air. This dust is produced during the
manufacture, the storage and the transport of the fertilizer
particles. The formation of the dust can be the result of the
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mechanical abrasion caused during the movement of the fertilizer
particles, continuous chemical reactions or curing processes
after the initial formation of the particle, the migration
action of moisture through the fertilizer during the storage, or
as a result of environmental temperature and humidity.
The diffusion of the fertilizer dust causes safety,
health, environmental, domestic economy and maintenance problems
for the producers, distributors and consumers of the fertilizer.
For example, the fertilizer dust causes human health risks due
to the inhalation thereof. Another problem associated to the
fertilizer dust transported by the air is the loss of agronomic
and economic value, whereas it potentially contributes to the
pollution of surface water ecosystems.
One of the most used solutions to solve the mentioned
problems consists of subjecting the recently manufactured
fertilizer, or after a curing period in the warehouse, to a
coating treatment with fluid compositions at the application
temperature, which quickly solidify or acquire sufficient
viscosity in contact with the granules.
Spanish patent application ES-A-2121694 of the applicant
describes anti-caking compositions for granular fertilizers
based on the joint use of mineral oils, primary fatty amines
(monoalkylamines in which the alkyl group is of fatty origin)
and alkyl phosphoric esters.
Spanish patent application ES-A-2179781, also of the
applicant, describes compositions which can prevent the caking
and the humectation of nitrogenous fertilizers at the same time.
Said additives do not contain fatty amines or their salts and
contain paraffins, paraffin oil and C2-C22 alkyl or C2-C12
alkylaryl phosphoric monoesters and/or diesters, possibly
alkoxylated. Said phosphoric esters can be totally or partially
neutralized with a Cl-C4 amine of the monoalkylamine,
dialkylamine, trialkylamine, monohydroxyalkylamine,
dihydroxyalkylamine or trihydroxyalkylamine type.
The description of the mentioned patent applications
includes a broad exposition of the state of the art relating to
anti-caking compositions for fertilizers, including specific
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references to relevant documents. Said descriptions are
incorporated herein by way of reference for the state of the art
on the mentioned anti-caking compositions.
Patent US-A-3926841 describes a composition for reducing
the caking of fertilizer particles, comprising:
a) 1-20% by weight of a cationic aliphatic amine selected
from amines of formula RR1R2N and RNHCH2CH2CH2NH2, wherein R is an
aliphatic hydrocarbon radical with 8 to 22 carbon atoms, Rl and
R2 are selected from H and alkyl groups with 1 to 22 carbon
atoms,
b) 3-80% by weight of a carboxylic acid selected from
aliphatic and cycloaliphatic carboxylic acids with 8 to 22
carbon atoms,
c) 0.1-5% by weight of an alkali selected from short-chain
alkanolamines in which the alkanol unit has from 2 to 4 carbon
atoms and hydroxides selected from magnesium hydroxide, zinc
hydroxide, nickel hydroxide and aluminium hydroxide, and
d) up to 90% by weight of an inert organic solvent
selected from mineral oils, waxes, polyethylene glycols and
mixtures thereof.
Although the formula RR1R2N includes monoalkylamines,
dialkylamines and trialkylamines, according to patent US-A-
3926841 the preferred amines are mixtures of saturated and
unsaturated n-aliphatic amines with 12 to 20 carbon atoms
(stearylamine, oleylamine or tallow amine)
European patent application EP-A-0113687 describes
ammonium nitrate granules coated with a composition consisting
of a homogeneous mixture of the following essential components:
a) 5-30% of a product obtained by the neutralization of
C12-C20 fatty monoalkylamines, optionally alkoxylated, with
phosphate esters corresponding to a very broad general formula
within which alkyl phosphate esters the chain length of which is
comprised between C4 and C12 are possible,
b) 25-70% of a mineral oil, which can be of the aromatic
type,
c) 10-25% of a coarsely-crystalline paraffin wax, and
d) 5-25% of a microcrystalline paraffin wax.
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European patent application EP-A-0341102 proposes the use
of mixtures of fatty amine salts with C8-C20 acid phosphate
esters, and with alkylarylsulfonic acids. The fatty amines can
be alkylamines, cycloalkylamines, aromatic amines and
alkanolamines, optionally alkoxylated. Said amines can be
primary, secondary or tertiary, C12-C20 fatty monoalkylamines,
such as technical-grade stearylamine or hydrogenated tallow
alkylamine, being preferred.
European patent application EP-A-0715884 describes
granular fertilizers which have been coated by a composition
comprising C12-C20 dialkylamines (R2NH) and C12-C20 monoalkylamines
(RNH2), in which the content by weight of monoalkylamine is
equal to or less than 75%. Said composition for coating the
granular fertilizers can further contain oils, waxes, inorganic
powders or anionic surfactants. As indicated in European patent
application EP-A-0715884, dialkylamines have been studied as
anti-caking agents and for preventing the formation of dust, as
described in FR-A-2062452. However, dialkylamines on their own
are not sufficiently efficient compared to the commonly used
monoalkylamine, stearylamine.
In addition, patent application FR-A-2062452 describes
granular fertilizers coated by a composition comprising at least
70% by weight of polyethylene with a molecular weight between
500 and 10000, in addition to aliphatic primary amines
(monoalkylamines) with 6 to 24 carbon atoms and/or aliphatic
secondary amines (dialkylamines) with 12 to 48 carbon atoms
and/or aliphatic tertiary amines (trialkylamines) with 12 to 60
carbon atoms and/or one or more ethylene oxide - propylene oxide
copolymers with a molecular weight between 1800 and 10000 and
containing between 10-80% by weight of ethylene oxide units.
Suitable amines according to patent application FR-A-2062452 are
stearylamine, cetylamine, mono-isotridecylamine, mono-
isononylamine, n-propyl-isononylamine, dimethyl
isotridecylamine, di-isotridecylamine and tri-isotridecylamine.
However, in the examples of the mentioned patent application it
is observed that the efficiency of trialkylamines is clearly
lower than that of monoalkylamines, and more specifically than
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that of stearylamine.
From the extensive state of the art set forth above, it is
clearly deduced that the problem of the anti-caking treatment of
granular fertilizers is complex and is far from being considered
5 completely solved. In fact, it is observed that more complex and
sophisticated solutions are increasingly proposed, which is not
very suitable for products such as fertilizers which need more
efficient, simple and economic alternative solutions due to
their high consumption and low price.
The inventors have developed certain compositions of
phosphoric esters and fatty trialkylamines which not only confer
anti-caking characteristics to granular fertilizers equivalent
to those provided by compositions based on phosphoric esters and
fatty monoalkylamines such as stearylamine, but which also,
since they have a lower melting point facilitating their
application on the fertilizer, require using less energy when
applying them on the fertilizer, as said application is normally
carried out by spraying, therefore said compositions must be in
fluid form. This energy saving is beneficial not only from the
economic point of view, but also from the environmental point of
view.
Summary of the Invention
As a result, the main object of the present invention are
compositions for preventing the caking of fertilizers in the
form of granular solids with an optimal anti-caking capacity and
a suitable melting point, said compositions comprising at least
one phosphoric ester and at least one fatty trialkylamine.
Another object of the present invention are fertilizer
compositions in the form of granular solids resistant to caking
characterized in that the granular solids are coated by a
composition comprising at least one phosphoric ester and at
least one fatty trialkylamine.
Another additional object of the present invention
consists of the use of the mentioned compositions for preventing
the caking of fertilizers in the form of granular solids.
Finally, another object of the present invention is a
method for obtaining fertilizers in the form of granular solids
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based on the application of the mentioned compositions on the
surface of the fertilizer granules.
Detailed Description of the Invention
Phosphoric esters
Phosphoric esters are products well known in the art. They
are usually obtained from the reaction between alcohols with
phosphorus pentoxide, and both the obtained products and the
mentioned reaction are known, more detailed information on them
being able to be found in the article published by O'Lenick et
al., in Soap Cosmetics and Chemical Specialties, July 1986, page
26.
Thus, suitable phosphoric esters for the object of the
invention are products well known by the person skilled in the
art, which are obtained by means of the reaction of C6-C24 fatty
alcohols or C2-C12 alkylphenols with phosphorus pentoxide, and
can possibly be alkoxylated by the reaction with 1-50 moles of
an alkylene oxide, mainly ethylene oxide and/or propylene oxide.
The obtained products are a mixture of monoesters and
diesters, the phosphoric esters of formula (I) and (II) being
preferred
Rl 0
1 11 [R2-0- (CH2-CH-0) n] -P- (OH) 2 ()
Rl 0
1 11
[R2-0- (CH2-CH-0) n] 2-P-0H (II)
wherein,
- Rl represents H, CH3 or C2H5,
- R2 represents a linear or branched alkyl, alkenyl or
alkynyl group containing between 6 and 24 carbon atoms,
and
- n represents a number comprised between 0 and 15,
preferably between 0 and 10,
or mixtures thereof.
For the purposes of the present invention, the products in
which the molar ratio of monoester (phosphoric esters of formula
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(I)) to diester (phosphoric esters of formula (II)) is comprised
between 90:10 and 30:70, more preferably between 85:15 and 50:50
are preferred, those in which the molar ratio of monoester to
diester is comprised between 70:30 and 55:45 being especially
preferred.
Phosphoric esters in which R2 represents a non-alkoxylated
linear or branched C6-C24 alkyl, alkenyl or alkynyl group (n
represents 0) are preferred, phosphoric esters in which R2
represents a non-alkoxylated linear or branched alkyl, alkenyl
or alkynyl group containing between 10 and 18 carbon atoms (n
represents 0) being especially preferred.
Examples of commercially available phosphoric esters are
those corresponding to the commercial reference FOSFODETO
1214/50 (coconut phosphoric ester with a 55:45 molar ratio of
monoester to diester), FOSFODETO 8050 (hydrogenated tallow
phosphoric ester with a 60:40 molar ratio of monoester to
diester) and FOSFODETO FJZ 903 (ethoxylated oleic alcohol
phosphoric ester with 3 moles of ethylene oxide with a 55:45
molar ratio of monoester to diester), marketed by KAO Chemicals
Europe.
Fatty trialkylamines
Fatty trialkylamines can be obtained by reacting fatty
alcohols with NH3, with alkylamines (RNH2) or with dialkylamines
(RR'NH), the suitable pressure, temperature conditions and
catalysts being well known for the person skilled in the art, as
described in the patent applications EP-A-EP0500038 or EP-A-
0908444.
Examples of fatty alcohols which react to obtain
trialkylamines are those from animal and vegetable fats and
oils, such as cotton, safflower, coconut, rapeseed, linseed,
palm, palm kernel, sunflower, olein, olive, olive pomace, castor
oil, tallow, soy, tall oil, etc, possibly totally or partially
hydrogenated, as well as purified or synthetic fatty acids such
as caproic acid, caprylic acid, capric acid, lauric acid,
myristic acid, palmitic acid, palmitoleic acid, stearic acid,
isostearic acid, 2-ethylhexanoic acid, oleic acid, ricinoleic
acid, elaidic acid, petroselinic acid, linoleic acid, linolenic
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acid, arachidic acid, gadoleic acid, behenic acid and erucic
acid, or mixtures thereof.
Suitable fatty trialkylamines according to the invention
correspond to the formula (III)
R3
I ( I I I )
R1-N-R2
wherein
- Rl represents a linear or branched alkyl, alkenyl or
alkynyl group containing between 6 and 24 carbon atoms,
preferably between 10 and 18 carbon atoms,
- R2 represents a linear or branched alkyl group
containing between 1 and 5 carbon atoms, preferably a
methyl group,
- R3 represents a linear or branched alkyl group
containing between 1 and 5 carbon atoms, preferably a
methyl group, or alkyl, alkenyl or alkynyl group
containing between 6 and 24 carbon atoms, preferably
between 10 and 18 carbon atoms,
or mixtures thereof.
Suitable fatty trialkylamines according to formula (III)
according to the invention are dimethyl octylamine, dimethyl
decylamine, dimethyl laurylamine, dimethyl myristylamine,
dimethyl palmitylamine, dimethyl cetylamine, dimethyl
stearylamine, dimethyl behenylamine, coconut dimethylalkylamine,
oleic dimethylalkylamine, tallow dimethylalkylamine, totally or
partially hydrogenated tallow dimethylalkylamine, or mixtures
thereof.
Other suitable fatty trialkylamines according to formula
(III) according to the present invention are methyldioctylamine,
methyldidecylamine, methyldilaurylamine, methyldimyristylamine,
methyldipalmitylamine, methyldicetylamine, methyldistearylamine,
methyldibehenylamine, coconut methyldialkylamine, oleic
methyldialkylamine, tallow methyldialkylamine, totally or
partially hydrogenated tallow methyldialkylamine, or mixtures
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thereof.
Examples of commercially available fatty trialkylamines are
those corresponding to the commercial reference FARMINO DM-2098
(dimethyl laurylamine), FARMINO DM-4098 (dimethyl
myristylamine), FARMINO DM-6098 (dimethyl cetylamine), FARMINO
DM-8098 (dimethyl stearylamine), FARMINO DM-2471 (coconut
dimethylalkylamine), FARMINO DM-0 (oleic dimethylalkylamine),
FARMINO DM-T (tallow dimethylalkylamine), FARMINO DM-TH
(hydrogenated tallow dimethylalkylamine), FARMINO M-D10
(methyldidecylamine), FARMINO M-2TH (hydrogenated tallow
methyldialkylamine), all of them marketed by KAO Chemicals
Europe.
Anti-caking compositions
Preferred compositions for preventing caking and crust
formation in fertilizers in the form of granular solids are
those comprising, in the indicated amounts expressed as
percentage by weight,
a) 30-90%, preferably 50-80% of at least one phosphoric
ester such as those previously described, and
b) 70-10%, preferably 50-20% of at least one fatty
trialkylamine such as those previously described.
The phosphoric ester (component (a)) can have its acidic
proton (in the case of the phosphoric ester of formula (II)) or
its acidic protons (in the case of the phosphoric ester of
formula (I)) partially or totally neutralized by the fatty
trialkylamine (component (b)). Said neutralization reaction is
followed by means of determining the acidity degree or index
(AI), which is an indicator of the amount of free acids present
in a sample, and which is expressed as the number of milligrams
of potassium hydroxide (KOH) necessary for neutralizing the free
acids in 1 gram of sample.
It is especially preferred that the phosphoric ester
(component (a)) has its acidic proton or protons partially
neutralized by the fatty trialkylamine (component (b)).
Although it is not strictly necessary, the use of an inert
solvent (component (c), which does not react with the components
(a) or (b)) for diluting the anti-caking compositions is
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convenient.
Preferred compositions are those comprising, in the
indicated amounts expressed as percentage by weight with respect
to the total weight of the composition,
5 a) 1-20%, preferably 5-15%, of at least one phosphoric
ester such as those previously described,
b) 1-20%, preferably 3-15%, of at least one
trialkylamine such as those previously described, and
c) 60-98%, preferably 70-92%, of an inert solvent.
10 Suitable inert solvents are mineral oils, paraffins and
waxes from petroleum, animal and vegetable fats and oils, fatty
acids, natural waxes and polyols, or mixtures thereof.
Suitable mineral oils, paraffins and waxes from petroleum
according to the present invention are:
- aromatic oils, which are a mixture of mineral oils from
petroleum with a high content of components having
aromatic type rings,
- white mineral oils, which are highly refined petroleum
derivatives, generally used as carriers, excipients and
lubricants in different industrial applications,
- paraffin oils, which are petroleum derivatives rich in
paraffin components and have low density and a variable
viscosity,
- macrocrystalline paraffins, which are petroleum
derivatives containing mainly linear carbon chains with
a molecular weight comprised between 250 and 500 and,
although they are solids at room temperature, they have
low melting points, usually comprised between 40 C and
70 C,
- microcrystalline paraffins, which are petroleum
derivatives and are mainly saturated hydrocarbons in
which linear chains with short branches (isoparaffins)
are predominant. They usually have mean molecular
weights comprised between 500 and 800, and are solids at
room temperature, having melting points comprised
between 70 C and 100 C.
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Suitable animal or vegetable fats and oils according to the
present invention are esters of linear and/or branched,
saturated and/or unsaturated alkanecarboxylic acids with a chain
length of 1 up to 30 carbon atoms and linear and/or branched,
saturated and/or unsaturated alcohols with a chain length of 1
up to 30 carbon atoms, of the group of esters of aromatic
carboxylic acids and linear and/or branched, saturated and/or
unsaturated alcohols with a chain length of 1 up to 30 carbon
atoms. These oils can be advantageously selected from the group
consisting of isopropyl myristate, isopropyl palmitate,
isopropyl stearate, isopropyl oleate, n-butyl stearate, n-hexyl
laurate, n-decyl oleate, isooctyl stearate, isononyl stearate,
isononyl isononanoate, 2-ethylhexyl laurate, 2-ethylhexyl
palmitate, 2-ethylhexyl cocoate, 2-hexyldecyl stearate, 2-
ethylhexyl isostearate, 2-octyldodecyl palmitate, cetyl
palmitate, oleyl oleate, oleyl erucate, erucyl oleate, erucyl
erucate, as well as synthetic, semisynthetic and natural
mixtures of such esters, such as jojoba oil (a natural mixture
of esters of monounsaturated monocarboxylic acids with a C18-C24
chain with also monounsaturated monoalcohols and with a long C18-
C24 chain). Other suitable oils of the type of esters of
saturated alkanecarboxylic acids and alcohols are fatty acid
methyl esters, preferably C6-C24 fatty acid methyl esters from
animal and vegetable fats and oils such as cotton, safflower,
coconut, rapeseed, linseed, palm, palm kernel, sunflower, olein,
olive, olive pomace, castor oil, tallow, soy, tall oil, etc,
possibly totally or partially hydrogenated, as well as purified
or synthetic fatty acids such as caproic acid, caprylic acid,
capric acid, lauric acid, myristic acid, palmitic acid,
palmitoleic acid, stearic acid, isostearic acid, 2-ethylhexanoic
acid, oleic acid, ricinoleic acid, elaidic acid, petroselinic
acid, linoleic acid, linolenic acid, arachidic acid, gadoleic
acid, behenic acid and erucic acid, or mixtures thereof.
Other suitable animal or vegetable fats and oils according
to the present invention are fatty acid triglycerides,
specifically triglycerin esters of linear and/or branched,
saturated and/or unsaturated alkanecarboxylic acids with a chain
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length of 6 up to 24 carbon atoms, preferably of 10 up to 18
carbon atoms. The fatty acids esterifying the different
positions of glycerin can be different, giving rise to a large
amount of possible combinations, including positional
combinations. The position of the different fatty acids in
natural triglycerides is not random, but rather it depends on
the origin of the fat. The triglycerides more simple are those
constituted by a sole fatty acid.
Fatty acid triglycerides can be advantageously chosen, for
example, from the group consisting of synthetic, semi-synthetic
and natural oils, as for example, animal fats and oils such as
cow tallow, pig lard, bone oil, aquatic animal fats and oils
(fish, such as herring, cod or sardine; cetaceans; etc.); and
vegetable fats and oils such as avocado oil, almond oil,
hazelnut oil, babassu palm oil, borage oil, peanut oil, canola
oil, hemp oil, milk thistle oil, safflower oil, chufa oil,
coconut oil, rapeseed oil, black cumin oil, wheat germ oil,
sunflower oil, linseed oil, macadamia nut oil, corn oil, walnut
oil, olive oil and its by-products such as olive pomace oil,
palm oil and its fractions such as palm olein and palm stearin,
evening primrose oil, rosehip oil, castor oil, rice bran oil,
apricot kernel oil, cottonseed oil, pumpkinseed oil, palm kernel
oil and its fractions such as palm kernel olein and palm kernel
stearin, grape seed oil, sesame oil, soy oil, cocoa butter, shea
butter and the like.
Suitable fatty acids according to the present invention are
C6-C24 fatty acids from vegetable and animal fats and oils such
as those previously described, such as cotton, safflower,
coconut, rapeseed, linseed, palm, palm kernel, sunflower, olein,
olive, olive pomace, castor oil, tallow, soy, tall oil, etc,
possibly totally or partially hydrogenated, as well as purified
or synthetic fatty acids such as caproic acid, caprylic acid,
capric acid, lauric acid, myristic acid, palmitic acid,
palmitoleic acid, stearic acid, isostearic acid, 2-ethylhexanoic
acid, oleic acid, ricinoleic acid, elaidic acid, petroselinic
acid, linoleic acid, linolenic acid, arachidic acid, gadoleic
acid, behenic acid and erucic acid, or mixtures thereof.
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Fatty acids of the lauric, myristic, palmitic, palmitoleic,
stearic, isostearic, 2-ethylhexanoic, oleic, ricinoleic, behenic
type, or mixtures thereof are preferred.
The fact that there is C6-C24 fatty acid in the inert
solvent (component (c)) in the compositions according to the
invention does not have the drawback of the formation of amides.
Said amides can be formed during prolonged storage periods,
especially at high temperatures, of the anti-caking
compositions, due to the condensation between said fatty acids
or their esters and monoalkylamines (primary amines). The
formation of amides can affect the anti-caking power of the
compositions.
Suitable natural waxes according to the present invention
are the candelilla wax, carnauba wax, Japan wax, esparto wax,
cork wax, guaruma wax, rice wax, sugar cane wax, ouricury wax,
montan wax, beeswax, shellac wax, espermaceti, wool lanolin
(wax), uropygial fat wax, ceresin waxes, peat waxes, ozokerite,
as well as chemically modified waxes (hard waxes) for example,
montan wax esters, waxes obtained by the Fischer-Tropsch
process, hydrogenated jojoba waxes and synthetic waxes.
Suitable polyols according to the present invention are
preferably water-soluble polyols such as polyhydric alcohols
with two or more hydroxyl groups in their molecule. Specific
examples can include ethylene glycol, propylene glycol, 1,3-
butylene glycol, 1,4-butylene glycol, dipropylene glycol,
polyethylene glycol with average molecular weights by weight
ranging between 100 and 1000, glucose, fructose, galactose,
mannose, ribose, erythrose, maltose, maltitose, maltotriose,
sucrose, xylitol, sorbitol, threitol, erythritol, glycerol,
polyglycerol and starch alcohols. Especially preferred are
polyols such as ethylene glycol, propylene glycol, 1,3-butylene
glycol, 1,4-butylene glycol, dipropylene glycol, polyethylene
glycol with average molecular weights by weight ranging between
100 and 1000, glycerol, polyglycerol, and mixtures thereof.
From the environmental point of view, animal and vegetable
fats and oils, fatty acids, natural waxes and polyols, or
mixtures thereof are preferred as inert solvent (component (c))
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according to the invention, since the use of petroleum
derivatives is thus avoided. Although for the person skilled in
the art it is evident that, alternatively, animal and vegetable
fats and oils, fatty acids, natural waxes and polyols can also
be combined with mineral oils, paraffins and waxes from
petroleum such that the resulting inert solvent (component (c))
has suitable properties from the environmental point of view
(biodegradability, ecotoxicity, etc.)
Fatty acid triglycerides such as those previously
described, C6-C24 fatty acids such as those previously described,
or mixtures thereof are especially preferred as inert solvent.
In the event of using C6-C24 fatty acids as inert solvent,
it is advantageous for the purposes of the present invention
that the content of C6-C24 fatty acids is comprised between 3-
100% by weight, preferably between 5-90% by weight, more
preferably between 10-80% by weight, with respect to the total
weight of the inert solvent (component (c)).
In addition, in the event of using mixtures of fatty acid
triglyceride and free C6-C24 fatty acids, it is suitable
according to the present invention that the fatty acid
triglycerides and the C6-C24 fatty acids have different carbon
chains.
The compositions object of the invention can be obtained by
means of conventional process for mixing the different
components, well known by the skilled person. Thus, for example,
the different components can be mixed in molten state and, once
the mixture has been homogenized, it is packaged and possibly
cooled.
The compositions object of the present invention have, in
relation to granular solid fertilizers, a broad field of
application since they are effective both for simple fertilizers
and for complex fertilizers. They are suitable for simple and
complex fertilizers of the N, NP, NK, PK and NPK type, being
especially preferable for complex fertilizers of the NPK type
(such as 15.15.15, 17.17.17, 13.13.21 or 8.24.16), providing
them with an efficient resistance against caking making said
fertilizers show excellent properties with regard to their
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breakdown even after their transport and storage period. Said
use also forms part of the present invention.
The compositions of the invention, in addition to fatty
trialkylamines, occasionally contain fatty monoalkylamines of
5 formula (IV)
R-NH2 ( IV )
wherein R represents a linear or branched alkyl, alkenyl or
alkynyl group containing between 6 and 24 carbon atoms,
preferably between 10 and 18 carbon atoms.
10 In the event of using as component (b) a mixture of fatty
monoalkylamines of formula (IV) and fatty trialkylamines of
formula (III), it is advantageous for the purposes of the
present invention that the content of fatty trialkylamines of
formula (III) is comprised between 20-80% by weight, preferably
15 between 30-70% by weight, more preferably between 35-75% by
weight, with respect to the total weight of said component (b).
In the event of using as component (b) a mixture of fatty
monoalkylamines of formula (IV) and fatty trialkylamines of
formula (III), despite the fact that it is possible for amides
to be formed between the fatty monoalkylamines of formula (IV)
and the fatty acids or their esters [in the form of component
(c)], said phenomenon is surprisingly reduced maintaining the
phosphoric ester [component (a)] in stoichiometric excess with
respect to the fatty monoalkylamines of formula (IV) and
completing the (partial or total) neutralization of the acidic
proton or protons of the phosphoric ester with the fatty
trialkylamines of formula (III).
The anti-caking compositions in which component (b) is a
mixture of fatty monoalkylamines of formula (IV) and fatty
trialkylamines of formula (III) are also suitable for preventing
the caking of fertilizers in the form of granular solids,
especially for fertilizers of the ammonium nitrate (AN) type.
Said use also forms part of the present invention.
A process for obtaining fertilizers resistant to caking,
wherein fertilizer granules are coated by applying on the
surface a composition as it was previously described, also forms
part of the object of the invention.
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The processes for applying the compositions are well known
by the skilled person and consist, for example, of applying the
additive (compositions according to the invention) in molten
state, by means of spraying techniques, on the surface of the
fertilizer granules once such fertilizer has been manufactured.
The amount of additive to be applied on the fertilizer will
depend on each case on the humidity, storage time and
temperature conditions expected for the storage of the
fertilizer, although good results can be obtained when said
compositions are applied on the fertilizer in proportions
comprised between 500 and 4000 ppm with respect to the weight of
the fertilizer.
The following examples are set forth for the purpose of
providing a sufficiently clear and complete explanation of the
present invention to the person skilled in the art, but they
must not be considered as limitations to the essential aspects
of the object thereof as they have been set forth in the
previous sections of this description.
Examples
Example 1. Preparation of the additives of the invention
1.1.- General method
The inert solvent is loaded in a vessel provided with
stirring at the necessary temperature for achieving a good
flowability in the end product, maximum 90 C. The mass is
maintained under stirring and the alkylamine in liquid state is
added. The mass is maintained under stirring and the phosphoric
ester in flakes or in liquid state is added, maintaining the
same temperature. The mass is left under stirring for 30 minutes
at the same temperature. Unloading and packaging are
subsequently performed.
1.2.- Prepared compositions
Compositions A, B, C, D, A', B', C' and D' (according to
the invention) and the comparative examples (CE1, CE2, CE3, CE4)
detailed in Tables 1 and 2, in which the amounts of the
indicated components are expressed as parts by weight of each
component added to each composition, were prepared following the
general method. The amine was added according to the desired
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degree of neutralization (partial or total neutralization of the
acidic protons of the phosphoric ester).
The melting point of said compositions was determined. To
that end, a thermoanalytical technique called Differential
Scanning Calorimetry (DSC) was used by means of a TA Instruments
apparatus, model DSC 2010.
Table 1.- Anti-caking compositions
Neutralization of the most acidic proton of the phosphoric ester
Components A B C D CE1 CE2
Stearylamine
(mixture of C16-C18 --- --- --- --- 5.5 5.5
monoalkylamine)
hydrogenated tallow
10.0 --- 10.0 --- --- ---
methyldialkylamine
coconut
--- 8.5 --- 8.5 --- ---
methyldialkylamine
Paraffin oil
(Extensoil0 200, of 80.0 81.5 --- --- 84.5 ---
Repsol YPF)
Crude rapeseed oil
--- --- 80.0 81.5 --- 84.5
(Gustav Heess)
FOSFODETO 80/50* 10.0 10.0 10.0 10.0 10.0 10.0
Melting point ( C)
76.6 57.2 82.9 59.8 93.4 97.4
[DSC (5 C/min) ]
~ hydrogenated tallow phosphoric ester with a 60:40 molar ratio
of monoester to diester
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Table 2.- Anti-caking compositions
Total neutralization of the phosphoric ester
Components A' B' C' D' CE3 CE4
Stearylamine --- --- --- --- 8.8 8.8
Hydrogenated
tallow 16.0 --- 16.0 --- --- ---
methyldialkylamine
Coconut
--- 13.8 --- 13.8 --- ---
methyldialkylamine
Paraffin oil
(Extensoil0 200, 74.0 76.2 --- --- 81.2 ---
of Repsol YPF)
Crude rapeseed oil
--- --- 74.0 76.2 --- 81.2
(Gustav Heess)
FOSFODETO 80/50* 10.0 10.0 10.0 10.0 10.0 10.0
Melting point ( C)
[DSC (5 C/min)] 75.3 60.9 84.0 67.3 100.9 106.2
hydrogenated tallow phosphoric ester with a 60:40 molar ratio
of monoester to diester
From the experimental data, it is evident that the anti-
caking compositions according to the invention have a lower
melting point than the compositions based on stearylamine, which
allows using a lower energy amount in order to be applied on the
fertilizers. This is observed with different types of inert
solvents.
Example 2. Evaluation method: accelerated caking test
With the compositions described in Table 1 of Example 1, a
(15.15.15) NPK complex granular fertilizer from the Huelva
(Spain) factory of the company FERTIBERIA, S.A., was treated by
means of spraying said molten compositions on the fertilizer, in
a rotary mixer, at a dose of 1000 ppm with respect to the weight
of the fertilizer (1 Kg/T).
Respective representative samples of fertilizer treated
with the anti-caking compositions and of untreated fertilizer
were subjected to an accelerated caking test consisting of
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introducing 90 g of fertilizer in cylindrical perforated metal
test tubes with a height of 60 mm and a diameter of 45 mm, which
can be longitudinally opened for extracting the samples, 3 test
tubes being used for each sample of fertilizer. The samples were
subjected to a pressure of 1.26 Kg/cm2 in an INSTRON
dynamometer, model 1011. The test tubes were maintained, at the
previously indicated pressure, at a relative humidity (R.H.) of
80% and at a temperature of 20 C for a period of 32 hours in a
HERAEUS climatic chamber, model HC 2057. The climatic conditions
were subsequently changed, passing to a R.H. of 20% and 40 C for
a period of 3 days.
Finally, the test tubes were left at environmental
temperature and humidity and the agglomerated pieces were broken
up, in the already indicated dynamometer, at a rate of 10
mm/minute.
The obtained result is expressed as the agglomeration
average in percentage and if the agglomeration has been
complete, also as the average resistance to break-up in kg.
The obtained results are shown in Table 3.
Table 3.- Results of the caking tests
Additive % of agglomeration Average resistance
(Dosing: 1 before break-up to break-up (kg)
kg/T)
A 100.0 11.1
B 100.0 8.4
C 100.0 12.0
D 100.0 8.7
CE1 100.0 12.0
CE2 100.0 12.5
Untreated blank 100.0 34.6
From the obtained results, it is deduced that the
compositions of the invention provide good results as anti-
caking agents, in some cases even somewhat better than those
obtained with the anti-caking additives based on stearylamine
(CE1, CE2)
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Example 3. Evaluation method: accelerated caking test
Other compositions according to the present invention were
tested following the method described in Example 2, this time
with the (26Ø0) NPK granular fertilizer from the Teruel
5 (Spain) factory of the company GRUPO AGRIMARTIN, S.L. The test
tubes were maintained, at the pressure indicated in Example 2,
at a relative humidity (R.H.) of 60% and at a temperature of
20 C for a period of 48 hours in a HERAEUS climatic chamber,
model HC 2057. The climatic conditions were subsequently
10 changed, passing to a R.H. of 20% and 40 C for a period of 3
days.
In addition to some compositions already described in
Examples 1 and 2, the compositions shown in Table 4 were tested.
Table 4.- Anti-caking compositions
15 Neutralization of the most acidic proton of the phosphoric ester
Components E F G
Hydrogenated tallow
10.0 --- ---
methyldialkylamine
Coconut methyldialkylamine --- 8.5 8.5
Palm kernel/coconut fatty acids
64 65.2 ---
(Lipidos Santiga, SA)
RBD palm stearin
16 16.3 ---
(Lipidos Santiga, SA)
Refined palm oil
--- --- 81.5
(Lipidos Santiga, SA)
FOSFODETO 80/50* 10.0 10.0 10.0
Melting point ( C) DSC (5 C/min) 58.3 49.3 60.5
hydrogenated tallow phosphoric ester with a 60:40 molar
ratio of monoester to diester
The obtained result is expressed as the agglomeration
average in percentage and if the agglomeration has been
20 complete, also as the average resistance to break-up in kg.
The obtained results are shown in Table 5.
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Table 5.- Results of the caking tests
Additive % of agglomeration Average resistance
(Dosing: 1 before break-up to break-up (kg)
kg/T)
C 0.0 ---
D 76.4 ---
E 8.7 ---
F 0.0 ---
G 80.2 ---
CE1 58.2 ---
CE2 55.9 ---
Untreated blank 100.0 33.1
From the obtained results, it is deduced, as in Example 2,
that the compositions of the invention provide good results as
anti-caking agents, in some cases even somewhat better than
those obtained with the anti-caking additives based on
stearylamine (CE1, CE2).
Compositions C, E and F are especially preferred.
The modifications which do not affect, alter, change or
modify the essential aspects of the described compositions are
included within the scope of the present invention.
