Note: Descriptions are shown in the official language in which they were submitted.
CA 02230892 1998-03-24 PCT('L 96/ O OU V'
1PEAIUS ()8 SEP POLYMER COATED POWDERS
Field of the Invention
The present invention. relates to a novel process for coating inorganic and
organic solids
with polymers, waxes and greases, at a temperature lower than the softening
temperature
of the original raw materials that constitute the coating. This process is
particularly
important for the preparation of surface coated powders of organic and
inorganic
materials such as Al, Cu, MgO, talc (3MgO=4SiO2=H2O), Mg(OH)2, CaCO3,
CaMg(CO3)2, MgCO3, Ca(OH)2, Ti02, A1203, Si02, CaSO4, Al(OH)3, cellulose
fibers, paper, glass fibers, alumina fibers, whiskers and platelets, SiC
fibers, whiskers
and platelets, TiN fibers and whiskers, other ceramic powders in the form of
oxides,
carbides and nitrides, and mixtures thereof. Also, it is an important process
for the
preparation of surface coated fertilizers, to prevent their caking and/or turn
them into
slow release fertilizers such as KNO3, KCl, (NH4)ZSO4, K2SO4, (NH4)H2PO4,
(NH4)ZHPO4, urea, etc. and mixtures thereof.
The present invention relates to a method for the production and uses of
materials coated
with polymers, waxes or greases. The invention makes it possible to produce
powders
of improved performance and compatibility with a variety of other materials,
namely,
minerals, plastics and cellulose, and lowers the cost of their production.
This invention
makes it also possible to glue two or more different materials together in an
unconventional and inexpensive manner.
The present invention is particularly important, inter a1ia, in the
fertilizers industry and
in the production of powders for the cement (construction) industry, for the
paper
industry, for the textile industry, for the cosmetics industry, for the
adhesives industry,
for the paint industry, for the ceramic industry, for the plastic and rubber
industries, etc.
AMEN ED Sk1EET
CA 02230892 1998-03-24 / O O~~
PCT/tL9 b fl
tpEAIUS p g SEP ' 97
2
Background of the Invention
Application of Surface-Modified Powders
The literature is replete with patents, articles, reviews and books concerning
the
production and beneficiation of minerals (e.g. "Mineral Processing"; E. J.
Pryor;
Elsevier Publishing; Third Ed.; 1965) and their uses, especially after surface
modifications, in the plastics compounding, in the paper industry, in the
ceramic
industry, in the paint industry, etc. (e.g. "CaCO3 Fillers - Market Trends and
Developments"; J. Revert'e i Vidal; Industrial Minerals; November 1994,
"Plastic
.... ~
Compounding - Where Mineral Meets Polymer"; M. O'Driscoll; Industrial
Minerals;
December "1994, "Surface Modification of Mineral Fillers"; R. Goodman;
Industrial
Minerals; February 1995, "Magnesium Hydroxide Flame Retardant (NHFR) for
Plastics
and Rubber"; O. Kalisky et al; Chimica Oggi/Chemistry Today; June 1995 and
references therein). The above reviews. illustrate the importance of the
physical
properties, and especially the surface characteristics, of fine powders that
are used in a
large variety of applications.
Size Reduction
Powders are intensively used in numerous applications, e.g. fillers and flame
retardants
in the paper and in the plastics industries, as raw materials for ceramics and
cements, as
constituents in cosmetics, etc.. In order to make effective use of powders,
their particle
size distribution should be controlled, usually reduced, and their surface
properties
should be compatible with those of the substrates with which these powders are
to be
used.
..-~:-.
Grinding or milling of materials are common technologies for size reduction.
However,
they require the expenditure of high energies, especially in the sub-micron
range, at
which the high surface area of the particles increases the rate of their
coalescence. The
AMENKSEfl S#-lEET
CA 02230892 2006-04-10
3
high cost of such operations is increased by their low productivity and by the
requirement for equipment made of special niaterials that withstand the high
attrition
and minimize the contamination of the final fine powders. Generally, two
processes are
used in the art - dry and wet grindinghnilling. In order to increase the
production rates of
both types of processes and to afford better qualities of grinding/milling,
aids, sucll as
dispersants like sodium hexametaphosphate, etc., are usually employed.
Another approach for obtaining fine powders involves their controlled
recrystallization
or precipitation by reacting suitable reactants.
In the cases described above, it is of great importance that any slurry of
fine powders be
stable, namely, that the fine particles will not undergo coalescence and the
solids will
not separate or precipitate even after long periods of time. Also, it is
required that the
final dry fine powders be free flowing. This can be achieved, among other
inethods, by
coating the fine particles with polymers, waxes or greases. However, the
softening
temperatures of oood coating materials are usually quite high, in order to
avoid their
displacement on storage or under regular use. Therefore, it is desired to use
coating
materials that are of low viscosity at relatively low teiiiperatures, at which
they are
applied, but after their application, it is desirable that their viscosity be
much higher.
Moreover, it is desired that the coating will be attracted specifically to the
surfaces that
are to be coated, prior to their curing process.
A recent Israeli patent application, IL 113283, filed April 6, 1995 by the
same applicant
discloses the use of certain carboxylic acid salts to improve
the production of fine powders.
Another recent patent application, IL 114853, filed August
7, 1995, by the same applicant herein, discloses a novel
CA 02230892 2006-04-10
3a
method for modifying the surface charges of inorganic
powders. The literature review in this patent application
is also pertinent to the present invention.
CA 02230892 1998-03-24 / O O n~
PCT/IL 9 6 0 7
p,IUS 0 S SEP '9~
PE
4
Glass Fibers
Glass fibers are used extensively in reinforcing materials. However, their
successful
application is dependent on the ability to modify their surface properties and
to
transform the fibers into materials compatible with their surroundings. This
is especially
true when the glass fibers are to be applied in plastics as well as in
cements. For
instance, any attempt to use glass fibers to reinforce portland cement is
doomed to fail,
as the alkaline cements attack the glass and degrade the product (cf. -"
Durability of E-
Glass Fibre Reinforced Composites with Different Cement Matrices"; by K.
Kolver and
A. Bentur of the National Building Research Institute; the Technion - Israel
Institute of
Technology; Haifa; Israel and I. Odler of the Institute of Non-Metallic
Materials; the
Technical University-Clausthal; Clausthal; Germany).
Naturally, the problem raised above can be solved by a variety of methods,
including
those described in the article of K. Kolver et al, but the prior art is unable
to furnish a
simple, inexpensive and readily operable solution. Similar problems are
encountered
when using other reinforcing materials like fibers, _ whiskers and platelets
of MgO,
A1203, SiC, TiN, etc.
Metal Powders
Metal powders are being used quite extensively in the plastics industry.
However,
their surfaces are not compatible with the hydrophobic plastics in which they
are to be
evenly distributed. Preparation of master batches of surface modified metallic
powders by simply mixing the fine particles with melted polymers, waxes or
greases
has its drawbacks. These coatings should eventually exhibit high viscosity at
the
temperatures at which the metallic powders will be stored prior to their use,
otherwise
the coating will undergo dislocation or the fine particles will coalesce.
A~~ c~.~ET
CA 02230892 1998-03-24 PCT/IL 9 6/ 00092
IpEANS n 9 SEN :91
The quality of the coating adherence to the metallic surfaces is another
problem that
should be taken care of, while using simple and inexpensive methods and
apparatus.
The prior art uses powerful high shear mixers at elevated temperatures to
obtain the
desired products. However, this method is still quite limited to polymers of
relatively
low viscosity, it requires the use of heated equipment and it does not lead to
sufficient
adherence of the coating to the metal powders. Another approach to solving
this
problem is to increase the degree of polymerization of the coating while
applying it on
the desired surfaces. This approach is quite sophisticated and requires a very
strict
synchronization of the different steps in the process.
Slow Release Fertilizers
Recently, a patent for a new production method of slow release fertilizers was
issued
to the present inventor (U.S. Patent No. 5,630,861, issued May 20, 1997), in
which
improved magnesite cements are used. This patent also refers to publications
that
review the prior art of this technology of forming water soluble fertilizers
coated with
water insoluble materials.
Generally, such fertilizers are coated with, at least, two different layers as
is
manifested in EP 0276179, in which carboxylate salts are coated, in aiw, on
the
respective fertilizers. Thereafter, a wax is coated onto the first layer. This
second layer
should either be applied at elevated temperatures, or the wax should be of a
low
melting range. This problem is particularly important when urea is to be
turned into a
slow-release fertilizer, since its low melting point does not allow the use of
high
melting waxes and, therefore, the second layer may lead to coalescence of the
urea
granules on storage under the harsh conditions at the storehouses and fields
of the
farms.
AMENDED SHEfT
CA 02230892 1998-03-24 PCTAL 9 b / 0 0 0 9
IFEm"'JS 0 8 SEP '97
6
It is quite clear that the use of a wax of a low viscosity at a relatively low
temperature,
of the magnitude of the temperature at which the second coating layer is
preferably
produced, that can be turned later in the process into a high viscosity layer
by simple
and inexpensive methods, is highly desirable.
CaCO, ' w rs
A typical and most important example is powdered CaCO3. Knowing the surface
properties of calcite, and understanding how to modify them in order to
improve its
performance as a major filler in the plastics and the paper industries, are of
prime
importance. Efficient processes of surface coating of calcite with suitable
polymers,
waxes or greases, which may contain other fine powders like Ti02 for improved
brightness, Al for improved electrical and heat conduction, are still quite
desired.
Miz(OFI)Z Powders
This material is used as a flame retardant in plastics and is a mild base. It
may be
produced by the hydrolysis of MgO in water. Performing the hydrolysis under
conditions at which the surfaces of the raw material and the product are
modified, may
enhance the production rate substantially and allow the obtaining of powders
that
contain mainly single crystals that are already surface coated with fatty acid
salts and/or
polymers, waxes or greases. Operation of the surface coating of brucite can be
done in a
similar manner as in the abovementioned case of calcite.
AI(OH)2_Powdeis
This material is used, among its other uses, as a flame retardant in plastics.
It may be
produced by the hydrolysis of A1203 in water. Performing the hydrolysis under
conditions at which the surfaces of the raw material and the product are
modified, may
enhance the production rate substantially and allow the obtaining of powders
that
AMENDED SkW
CA 02230892 1998 03 24 PCT/IL 96 ~ 00 0 g~,
IPEWS a SEP f 9
7
contain mainly single crystals that are already surface coated with fatty acid
salts and/or
polymers, waxes or greases. Operation of the surface coating of the Al(OH)3
can be done
in a similar manner as in the abovementioned cases of calcite and brucite.
The desire to turn hydrophilic surfaces of powder minerals into hydrophobic
ones is
general to a. great - many materials such as CaMg(CO3)2, MgCO3, talc
(3MgO=4SiO2=H2O), Ca(OH)2, CaCO3, Ti02, A1203, Si02 and CaSO4.
Surprisingly, it was found that the surfaces of organic and inorganic powders
(e.g.,
metals like Al, Cu and Mn; natural and artificial minerals like MgO, talc
(3MgO=4SiO2=H2O), Mg(OH)2, CaCO3, CaMg(CO3)2, MgCO3, Ca(OH)2, A1203,
Al(OH);, Ti02, Si02, CaSO4; fibers, whiskers and/or platelets of cellulose,
glass,
alumina, MgO, SiC, TiC, TiN; fertilizers like KNO3, KCI, K2SO4, (NH4)2SO4,
(NH4)H2PO4, (NH4)2HP04, urea; organic and inorganic pigments like
quinacridones,
mineral oxides of iron or copper, etc.) can be coated at relatively low
temperatures with
"coating solutions", which are liquids or waxy materials of low viscosity, and
these
coatings can then be turned into hard, high viscosity materials by simple
chemical or
physical interactions.
It is a purpose of the present invention to provide an inexpensive and simple
method to
produce fine powders, fibers, whiskers, platelets and/or granules that are
coated 'with
polymers, waxes or greases of high quality.
It is a further purpose of the invention to provide methods to improve these
particles by
coating them with suitable carboxylic acid salts and other additives.
It is a further purpose of the invention to provide methods to produce these
coated
particles using common and inexpensive raw materials and equipment.
AMENDED SHEET
CA 02230892 2003-08-28
8
It is fiirther purpose of the present invention to demonstrate the uses of
these coated
particles, which are obtained by this novel coating method.
Otlier purposes and advantages of the invention will become apparent as the
description
proceeds.
Summary of the Invention
Surprisingly, it has been found that carboxylic acid solutions of sparingly
water soluble
polymers, waxes and/or greases like polyetllylene (PE), polypropylene (PP),
silicone
rubbers, ethylene-acrylic acid copolymers, ethylene-maleic acid copolymers,
ethylenevinylacetate copolymers and many others, which are extremely soluble
in
carboxylic acids at quite low temperatures, namely, at substantially lower
temperatures
than the softening point of the respective pure polymers, can be spread quite
easily and
economically, as thin or thick films, onto the surface of solids, especially
onto the
surface of fine powders. Furthermore, it has been found that these low
viscosity liquids
can then be altered to precipitate the higli viscosity materials therein by
simply
transforming the carboxylic acids into the carboxylate forms by reacting them
with
suitable basic reagents, for example, aqueous solutions of ammonia and
inorganic bases.
Alternatively, the suitable carboxylic acids may be dissolved in an aqueous
mediuni
leading to the precipitation of the polymers onto the desired surfaces.
Note that, as used herein, the term "sparingly water soluble" nieans that the
polymers,
waxes, or greases used as coating materials are either insoluble or only
slightly
soluble in water.
Thus, the invention as claimed hereinafter is denoted to a
CA 02230892 2003-08-28
8a
process for coating a solid with at least one coating
material, comprising the steps of:
(a) selecting the at least one coating material from the group consisting of
water insoluble or slightly water soluble polymers, waxes,
and greases;
(b) dissolving the coating material in a carrier including at least one
carboxylic compouncl selected from the group consisting of carboxylic
acids, carboxylic acid anhydrides and carboxylic acid halides, thereby
creating a coating solution;
(c) spreading said coating solution on the solid; and
(d) precipitating the coating material onto the solid by a metliod selected
from the group consisting of:
(i) transforming said at least one carboxylic compound into a
carboxylic derivative and
(ii) dissolving said at least one carboxylic compound in a solvent.
CA 02230892 2006-04-10
9
This invention leads to the following major improvements over the prior art
that is
associated with coating of the hydrophilic surfaces of many fine powders with
hard and
adherent Izydropliobic t11in filnls of polyniers, waxes or greases:
I. Spreading of the polymers can be done with siniple niixers rather than with
very
powerful higli shear mixers that are equipped with heating systems, as are
required in
the prior art.
2. The coating procedure can be carried out under relatively low temperatures,
even at
ambient temperature, while the polymers that are being used to coat the fine
particles
can be melted only at much higher temperatures. This allows the choosing of a
larger
variety of better suited polymers, i.e. with a quite higher softening
temperature range,
to coat materials of relatively low melting range. For instance, coating of
urea
granules with Epolene*wax E-43 of Eastman Kodak is rather impossible without
causing the particles of urea to melt (in this case the application of
dissolved polymer
in a suitable organic solvent is economically doomed). There is a rather large
variety
of nlaterials that can, and should, be encapsulated with high melting waxes.
However,
this cannot be done unless the polymers are emulsified in water, or inert
solvents are
to be used. These must be recycled at the end of the process with high
expenses and
may cause the pollution of the environment and the product itself.
3. The precipitation of the polymers, and usually the precipitation of the
respective
carboxylate salts together with it, can be targeted towards pre-selected
surfaces, that
were surface-modified in advance This, in turn, may lead to substantial saving
of the
coating. as a thorough coverage is obtained with less polymers.
This invention is not at all limited to water or aqueous solutions. In some
cases at
which the surfaces of the powders to be coated are of basic nature (e.g.
metals, metal
* trademarks
CA 02230892 1998-03-24 MTAL g 6 / 000 9 {PEA/t1S 08 SEP I?' '
oxides and metal hydroxides, and metal carbonates), the chemical reactions
occur with
the carboxylic acids. in the absence of practically any solvent and lead the
precipitation of the polymers, waxes and/or greases out of the coating
solution onto
these active surfaces.
Organic solvents can (and should) be applied according to the present
invention in
cases as follows:
a. The chemical properties of the coated powders forbid the use of aqueous
media.
b. The required quality of the resulting coating can not be obtained in a
solventless
operation or in aqueous media.
and naturally it is preferred that
c. The ecconomics of these operations (a. and b.), including recycling of the
solvents, =
be viable.
The present invention, therefore, relates, inter alia, to a novel process for
the coating of
polymers, waxes and greases onto and/or in between inorganic and organic
solids at a
temperature that is usually much lower than the softening temperature of these
original
raw materials that constitute the coating.
The process of the invention is particularly important for the preparation of
surface
coated powders of inorganic materials such as Al, Cu, Mn, MgO, talc
(3MgO=4SiO2=H2O), Mg(OH)2, CaCO3, CaMg(C03)2, MgCO3õ Ca(OH)2, Ti02,
A1203, Si02, CaSOq4, Al(OH)3; fibers, whiskers and/or platelets of cellulose,
glass,
alumina, magnesia, ceramic carbides such as SiC and TiC, ceramic nitrides such
as TiN,
etc.; and mixtures thereof. Also, it is an important process for the
preparation of surface
coated free flowing fertilizers and especially of slow release fertilizers
like KNO3, KCI,
(NH4)2SO4, K2SO4, (NH4)H2PO4, (NH4)2HP04, urea, etc. and mixtures thereof.
The invention, i,nter alia, relates to a method for the production and uses of
materials
coated with polymers, waxes or greases. This invention makes it possible to
produce
AMENDED SHEET
CA 02230892 1998-03-24' PCThL -9 v/ 0 0 U 1)
~v~ g SEN '
11
powders of improved performance and compatibility with a variety of other
materials,
namely, minerals, plastics and cellulose, and lowers the cost of their
production. This
invention makes it also possible to glue two or more different inaterials
together in an
unconventional and inexpensive manner.
The present invention is particularly important in the fertilizers industry
and in the
production of powders for the cement (construction) industry, for the paper
industry, for
the cosmetics industry, for the adhesives industry, for the paint industry,
for the ceramic
industry, for the plastic and rubber industries, etc.
Detailed Descrintion of Preferred Embodiments
The preparation of the "coating solutions" by mixing suitable polymers, waxes
and/or
greases with suitable carboxylic acids can be easily done, using simple
mixers. The
dissolution temperature may be below the softening temperature of
the,.respective
polymer, wax or grease, near it or above it. Naturally, it is preferred to
produce the
"coating solutions" at ambient temperature, if that is possible, in order to
save the cost
of mixers with heating systems. The "coating solutions" may be stored, later
at a
temperature in the liquid state or below its pour point, as a soft paste.
Another
possibility is to prepare the desired polymers, in ait11, by polymerising the
respective
monomers, dimers and/or oligomers in the carboxylic acid mixtures. A large
variety
of water insoluble or slightly water-soluble polymers, copolymers, block
copolymers,
grafted copolymers and mixtures thereof can be used in this invention.
The carboxylic acids may be applied in their acid form and/or their anhydride
form
and/or their acyl halide form. These forms are referred to herein collectively
as
"carboxylic compounds". The carboxylic compounds serve mainly as carriexs for
the
polymers, waxes and/or greases to be used for the coating. The forms to which
these
compounds are transformed chemically to precipitate the coatings onto the
solid
AMENDEp ~T
CA 02230892 1998-03-24 PCT/tl 9 6/ 0 0 0 97-
1PEAIUS 0 8 SFP 91
12
surfaces, i.e., carboxylates, esters and amides, are referred to herein
collectively as
"carboxylic derivatives". One should be aware of the fact that the anhydrides
may be
more reactive than the respective acids in aqueous solutions, in which they
may be
immersed in later applications. The acyl halides are more reactive and
corrosive under
certain conditions. Carboxylic acids containing one or more COOH groups may be
used' However, the choice of the right acid should be made on a
cost/performance
basis. The longer the carbon chain of the carboxylic acid, the lower is its
solubility in
water.
The kind of cations that can be used when transforming the carboxylic acids,
carboxylic acid anhydrides and/or carboxylic acid halides into the respective
carboxylates may have a marked effect on the performance of the process and
the
quality of the final products - the coated objects. For instance, All, Ca++
and Mg++
may give rise to extremely water soluble salts of propionic acid, while these
cations
lead to salts of palmitic or oleic acids that are slightly soluble in water.
Alkali and
ammonium cations may lead to soaps, which in turn may assist in spreading the
coating evenly onto the surface of the substrate. However, the choice of which
carboxylic acids and/or of which cations to use can not be prescribed. It is
worthwhile
to note that, sometimes, mixing of various constituents may lead to a better
cost/performance.
The carboxylic acids and/or carboxylic acid salts and/or the carboxylic acid
anhydrides
and/or the acyl halides may or may not have polymerized, in aitu, during the
production
of the coating, or may have partially polymerized, in aiW, during the
production of the
coated powders, and when they have polymerized they may be dimerized andlor
oligomerized and/or polymerized in the presence or the absence of any added
polymerization initiators. The polymerization initiators, if added, are
selected from
among organic azo compounds and organic peroxide compounds, such as
AMENDEA 'SWET
CA 02230892 1998-03-24 ~(!'f~~L 9 b/ p p 0 9~.
~ ~ ~PEp,US 08 SEN
13
percarboxylates; inorganic peroxides, such as. hydrogen peroxide, persulfates,
percarbonates and perborates.
As mentioned above, the surface of the substrate may be pre-treated in order
to target the
coating onto the right surfaces and to effect chemical bonds of the coating
with these
surfaces.
The choice of the more suitable hydrophobic polymers, waxes or greases is
within the
scope of the skilled person, and in many cases, polymers of high softening
temperatures and high viscosity are preferred. In other cases modified
polymers,
grafted with hydrophilic or hydrophobic groups, are used to obtain a better
binding to
the substrate surfaces. Mixtures of polymers can also be used, however, any
one,
skilled in the art may find the optimal choices.
Other additives that are commonly used in the art are chosen from among
organic and
inorganic colorants and pigments. Of course, other conventional additives can
also be
added. In a preferred mode of operation, these additives may be pre-mixed with
suitable
_., carboxylic acids, with the " coating solution"s and/or with the substrate
that is to be
coated.
CA 02230892 1998-03-24 PCTAL 9 6 f 0009
1PENUS 0 a SEP '9
14
Organic Solvents:
Though water and aqueous solutions offer outstanding economical and
technological
advantages in many applications, a large variety of organic solvents can be
used to
cause the precipitation the polymers, waxes and/or greases from the "coating
solution". Non-limiting examples are organic solvents, which are commonly
grouped
according to their functional groups, like hydrocarbons (saturated and
unsaturated;
cyclic and acyclic; linear and branched; halogenated - e.g. hexane,
cyclohexane,
toluene, xylene, etc.), alcohols (e.g. methanol, ethanol, 2-ethylhexylalcohol,
etc.)
aldehydes/ketones (e.g. propanal, acetone, 2-butanone, 2-hexanone, etc.),
nitriles (e.g.
acetonitrile, etc.), ethers (e.g. ethylether, monoglyme, diglyme, etc.),
esters (e.g.
ethylacetate, methylacetate, butylacetate, etc.), amides (e.g.
dimethylformamide,
dimethylacetamide, etc.) and/or sulphones/sulphoxides (e.g. sulfolane,
dimethylsulphoxide, etc.). More than one solvent comprising one or more
fiinctional
groups can be used (e.g. ethylene glycol, ethylene glycol monomethylether,
diethylene
glycol, etc.).'Moreover, aqueous solutions of organic solvents may be used to
reduce
M1 the surface tension or to ar
hieve some special effects.
It is very common in organic chemistry and in the daily industrial practice,
to assign
the solvents, depending on their nature, into groups according to the
following
categories: polar/nonpolar and protic/aprotic. The properties of the various
solvents
consequently affect the kind of interactions with the carboxylic compounds and
lead
to the modification of the properties of the "coating solutions" and to the
precipitation
of the polymers, waxes and/or greases:
polar/nonpolar solvents:
The polarity of the organic solvents may be affected by the kind of functional
group(s)
it carries and/or by the size of their hydrophobic hydrocarbon parts.
{ AENbEO
CA 02230892 1998-03-24 - PCTAL 96/ 00092
lP~S n ~ SEP 91
protic/aprotic solvents:
The nature of the funetional group(s) of the organic solvents may be protic
(able to
donate a proton under the conditions of the application - e.g. alcohols, etc.)
or aprotic
(unable to donate a proton under the conditions of the application - e.g.
ketones,
nitriles, dimethylsulphoxide (DMSO), dimethylacetamide, etc.).
Under these categories toluene is considered a nonpolar/aprotic solvent and
dimethylsulphoxide (DMSO) is considered a polar/aprotic solvent (note: water
can be
corisidered a polar/protic solvent). The protic solvents are distinct in their
tendency to
react with the carboxylic acid anhydrides and/or carboxylic acid halides,
whicll may
lead to the respective products, that are no longer able to act as carriers
and dissolve
the polymers, waxes and/or greases, thereby leading to their precipitation.
For
instance, alcohols react with carboxylic acid anhydrides and/or carboxylic
acid
halides and form =the respective carboxylic acid esters. On the other hand
alcohols
(like water) may mix well with the carboxylic acids, altering their physical
properties
and leading to the formation of the desired coating. In most"cases, amines may
not be
used as solvents, but rather as basic reagents, as they interact with the
carboxylic
acids, carboxylic acid anhydrides and/or carboxylic acid halides to form
carboxylic
acid salts or amides, respectively. Acetone, dimethylsulphoxide,
dimethylacetamide,'
and acetonitrile, which represent aprotic solvents, will only dissolve the
suitable
carboxylic acids, carboxylic acid anhydrides and/or carboxylic acid halides
and cause
the desired coating onto solids/powders.
Naturally, the use of such solvents requires their recycling and/or proper
waste
treatment. Such operations may be justified in cases at which the formed fine
powders
are expensive and/or there are no comparable alternative options to use water.
AMENOEtI SH&
CA 02230892 1998-03-24 pCTAL 9 6/ 0 00 92
1
tPws 0 8 SEN 97
..:.
16
In some cases the water and/or organic solvents, with or without suitable
reactants like
acids or bases, may. also cause chemical changes of the polymers, waxes and/or
greases and their subsequent precipitation. However, that can be achieved very
rarely
without affecting the carboxylic compounds.
Surface active agents can be added to the "coating solutions", to the solvents
or can be
formed by reacting suitable bases with the carboxylic acids, carboxylic acid
anhydrides and/or carboxylic acid halides, as mentioned before.
In many cases the solids/powders to be coated by the polymers, waxes and/or
greases
are basic materials. In such cases contacting these solids/powders with the
coating
solution may lead to a reaction with the carboxylic compounds and the
precipitation
of the polymers, waxes and/or greases onto their surfaces. In other cases the
surfaces
of the solids/powders to be coated can be turned basic prior to the
application of the
coating solution (e.g. glass surface modified with fluorides and/or
basic,silicates), in
order to initiate the reaction with the carboxylic compounds and to effect the
precipitation of the polymers, waxes and/or greases. The phenomenon that was
described above can be carried out in the presence or the absence of suitable
solvents.
It should be noted that the precipitation of the polymers, waxes and/or
greases out of
the "coating solutions" onto the solids/powders may be slow even when water or
solvents are used. Therefore, it is possible to operate the coating process in
quite
different ways. For instance, the solid to be coated can be contacted first
with the
"coating solution" and later with the solvent(s) and/or the suitable reagents,
it can be
contacted first with the solvent(s) and/or the reagents and later with the
"coating
solution", it can be contacted with a mixture of the "coating solution" and
the
solvent(s) and/or the reagents in a coating process in which all the
components are
added simultanously or it can be contacted with a mixture of the "coating
solution"
and the solvent(s) and/or the reagents, that were mixed togather and
maintained under
AMENDtD ~~-
CA 02230892 1998-03-24 PGTAL 9 6 / 0 0 0 9~
,PEA~~ 0 8 SEN '97
17
agitation quite a short time prior to the application. This short time
mentioned above
is optimally defined as the time that the precipitation process of the
polymers, waxes
and/or greases still take place.
A particularly important mode of operation are the continuous (and
semicontinuous)
processes, at which the fine particles of the product are formed and are being
coated,
simultanously in situ, by polymers, waxes and/or greases that precipitate all
along. A
non-limiting example of such a process is the production of PCC (precipitated
calcium
carbonte) at which the slurry of calcium hydroxide, the "coating solution' and
the
carbon dioxide are fed simultanously into a flotation cell.
There are numerous options to operate this novel technology. Therefore, the
optimal
operation, in each case, may be achieved by the person skilled in the art.
All the above and other characteristics and advantages of the invention will
be better
understood through the following illustrative and non-limitative description
of preferred
embodiments.
CA 02230892 1998-03-24 / O O~~~
PCT/IL 9 6
PEMA 8 'StN t91
18
Experimental Data
Rativ Materials
Carboxylic acids or Fatly Acids
-Propionic Acid of Aldrich -FA-1
-Caprylic Acid of Aldrich -FA-2
-Capric Acid of Aldrich -FA-3
-2-Ethylcaproic Acid of Aldrich -FA-4
-Tall oil of Arizona Chemical Co. -FA-5
-Lauric Acid of Aldrich -FA-6
-Palmitic Acid of Aldrich -FA-7
-Oleic Acid of Aldrich -FA-8
-Valeric Acid of Aldrich -FA-9
-Nitrilotriacetic Acid (NTAH3) of Aldrich -FA-10
-Phthalic Anhydride of Fluka -FA-11
-Maleic Anhydride of Fluka -FA-12
-2-Ethylhexanoyl Chloride of Aldrich -FA-13
Po]ymers. Waxes and Greases
-Polyethylene of Allied Signal, Grade 6-A -POL-I
-Polyethylene Acrylic Acid Copolymer of Allied Signal, Grade 540-A -POL-2
-Polyethylene Grease of Allied Signal, Grade 1702 -POL-3
-Polyethylene Acrylic Acid Copolymer of Allied Signal, Grade 5180 -POL-4
-Epolene Wax of Eastman Kodak, Grade E-43 -POL-5
-LDPE of Carmel Olefines, Grade Ipethene-900 -POL-6
AWNDEb sx
CA 02230892 1998-03-24 PCTAt 96/ 00092
%PEplus 08 SEP #97
19
Organic Solvents
Saturated and Unsaturated j3,vdrocarbons
-Toluene of Aldrich
-Hexane of Aldrich
-Cyclohexane of Aldrich
Alcohols
-Ethanol of Aldrich
-Diethyleneglycol of Aldrich
Aldehydes/ketones
-Acetone of Aldrich
-Ethylmethylketone of Aldrich
Ethers
-Diglyme of Aldrich
-Monoglyme of Aldrich
Esters
-Ethylacetate of Aldrich
Nitriles -Acetonitrile of Aldrich
Affiidg-,s
-Dimethylacetamide of Aldrich
Sulnhones/Sulphoxides
-Sulfolane of Aldrich
-Diinethylsulphoxide of Aldrich
AMEIUDLp S~-f~~fi_
CA 02230892 1998-03-24 KTAL 9 6 I 00 0 9 2
IPENvS 0 8 sEN '97
Inoraanic Materials
-Calcined MgO, a product of Grecian Magnesite grade "Normal F" - "MgF"
-Glass Fibers of Owen-Corning of Diameter of 10-13 Microns and Nominal Length
L=4.5 mm
-Calcium Hydroxide (Ca(OH)2) of Frutarom
-Potassium Sulfate (K2SO4) of Frutarom
-Potassium Chloride (KC1) of Frutarom
-Mono Ammonium Phosphate (MAP) of Aldrich
-Triple Super Phosphate (TSP) of Rotem Fertilizers Ltd
MgSO4 solution having a density of d=1.2 g/cm3 where the ratio H2O/MgSO4 =
3.1
-MgC12 solution having a density of d=1.267-1.27 g/cm3 where the ratio
H2O/MgC12=2.61
-CaCO3 powder (d50=5 microns) of Polychrom, Israel- "Girulite-10"
-CaCO3 powder (d50=18 microns) of Polychrom, Israel- "Girulite-40"
-Sodium Silicate Solution ( 14% NaOH and 27% Si02) of Fluka
-Ferric Chloride (FeCI3) of Riedel-de Haen
-Ferrous Sulfate (FeSO47H2O) of Riedel-de Haen
-Aluminum (Al) metal powder of Moniplet & Estban S.A, Spain- Grade
Panreac/P.R.S
Raw materials of high purity are not of prime importance. Commercially
available
materials can be used.
AMPIVntn ~-.~
CA 02230892 1998 03 24 PCT/'L 9 6 / 0 0 0 9
1PENUS 0 8 SEP '0
21
F,xamAle 1
Preparation of Coating Solutions in Carboxylic Acid(sl
A glass beaker equipped with a magnetic stirrer, a heater and a thermometer
was used to
dissolve polymers, greases and waxes in carboxylic acids and/or carboxylic
acid
anhydrides and/or carboxylic acid halides. The dissolution was conducted at a
temperature range much below the softening temperatures of the corresponding
polymers, greases and waxes during up to 30 mins.. Clear and transparent
liquids of
relatively low viscosity were obtained. Several examples are given in Table 1
below:
Table 1
Type of Type of Type of Load of Polymer Temperature
Test # Carboxylic Acid Carboxylic Acid Polymer % (wt) C
1 Propionic FA-1 POL-3 30 30
2 Caprylic FA-2 POL-4 40 30
3 Capric FA-3 POL-1 35 40
4 2-Ethylcaproic FA-4 POL-4 45 35
Valeric FA-9 POL-2 35 40
6 Tall Oil FA-5 POL=5'' 30 25
7 Lauric FA-6 POL-5 30 50
8 Palmitic FA-7 POL-5 30 70
9 Oleic FA-8 POL-5 60 25
Palmitic FA-7 POL-6 35 70
11 Tall Oil FA-5 POL-6 30 50
12 Oleic FA-8 POL-6 30 50
13 Phthalic Anhyd. FA-10 POL-5 25 140
14 Maleic Anhyd. FA-1 1 POL-5 25 60
2-Ethylhexanoyl FA-12 POL-6 20 60
Chloride
Remarks:
1. Acids, acid anhydrides and also acyl halides.
AME1dDE7 S*Efi
L
CA 02230892 1998-03-24 PCT/IL 9 6/ U U U'1
0 a StN '97
22
2. The viscosity of the solutions may be increased by e.g. reducing the
temperature or
by increasing the polymer concentration. Depending on the specific
combinations
(e.g. polymers and acids) and the relative concentrations of the constituents,
soft and
stable pastes can be obtained at ambient temperatures.
~; ~.. .
Y. q
~ . ~ AlZ1Gt~ ~~.~-.~. = _
CA 02230892 1998-03-24 PCT/ - lL 9 b / 00092
08 SEi'=97
23
Example 2
Production of Surface Coated Mg(OH)) Fine Powder
Surface coated Mg(OH)2 fine powder was obtained in the following manner:
Raw Materials Per One Batch
-100g calcined MgO
-100g water at 50 C
-1.5g propionic acid (FA-1)
-2.Og MgSO4 brine
-2.Og solution of tall oil (FA-5) + Epolene wax (POL-5) (80% (wt) and 20%
(wt),
respectively)
The warm water and the MgO were introduced into a beaker (cf. - Example 1).
The
slurry was stirred and the temperature was kept at 50 C during the test. Then,
the 6ther
reagents were added simultaneously to the stirred slurry and the mixture was
allowed
to stir for a total duration of 40 mins.. The slurry was then filtered off
(the pH of the
supernatant was in the range of 9.5-10); the solid was dried for 15hrs. in an
oven at
110 C; the dry cake was disintegrated into a fine powder.
The fine powder was subjected to the following tests:
1. XRD revealed that the product is brucite (Mg(OH)2).
2. SEM revealed hexagonal crystals of 0.5 micron (average).
,...
3. Flotability test using Modified Halimond Tube (a well known floatability
tests - cf.
"Mineral Processing"; E. J. Pryor; Third Ed.; Elsevier Publishing Co.; 1965;
pp. 463-
468) revealed 100% surface coated product (namely, hydrophobic brucite fine
particles).
p nC~,,nr~ ~ .
( =Lf~YC~/
= CA 02230892 1998-03-24 ~ 00092
PCTIIL 9 b
tPEAIUS n R SEPV
24
Example 3
A. Production of Surface Coated Glass Fibers in Water
Surface coated glass fibers were obtained in the following manner:
Raw Materials Per One Batch
-100g glass fibers
-550g water at 50 C
-0.5g sodium silicate solution
-2.Og MgSO4 brine
-3.Og coating solution of oleic acid (FA-5) + Epolene wax (POL-5) (80% (wt)
and
20% (wt), respectively)
-0.5g_calcined MgO
The warm water and the glass fibers were introduced into a beaker (cf. -
Example 2).
The sodium silicate solution and the MgSO4 brine were added to the stirred
mixture
after 10 mins. and it was allowed to stir for additional 2 mins. (the pH of
the mixture
was then at -9). The coating solution was added and the mixture was allowed to
stir
for additional 6 mins. The MgO was then added and the mixture was allowed to
stir
for additional 2 mins.. The whole experiment was carried 'out at 50 C.
The glass fibers were filtered off and dried in a oven at 110 C for 15 hrs..
The dry cake was subjected to a flotability test using Modified Halimond Tube
(a well
known floatability test - cf. "Mineral Processing"; E. J. Pryor; Third Ed.;
Elsevier
Publishing Co.; 1965; pp. 463-468) which revealed 1.00% surface coated product
(namely, hydrophobic glass fibers).
CA 02230892 1998-03-24 PCT/IL 9(, / 0 0 0 y Z
iPEA/US n p SEP '97
R. Production of Surface Coated Glass Fibers in Organic Solvents
Surface coated glass fibers were obtained in the following manner:
Raw Materials Per One Batch
-100g glass fibers
-550g organic solvent
-3.Og coating solution of propionic acid (FA-1) + Epolene wax (POL-5) (80%
(wt)
and 20% (wt), respectively)
The organic solvent and the glass fibers were introduced into a beaker (cf. -
Example
2). The mixture was allowed to stir for additional 10 mins.; the coating
solution was
added and the mixture was allowed to stir for additional 5 mins. The whole
experiment was carried out at 30 C.
The glass fibers were filtered off and dried in a vacuum oven (30 mm Hg) at
100 C
for 15 hrs..
The dry cake was subjected to a flotability test using Modified Halimond Tube
(a well
known floatability test - cf. "Mineral Processing"; E. J. Pryor; Third Ed.;
Elsevier
Publishing Co.; 1965; pp. 463-468) which revealed 100% surface coated product
(namely, hydrophobic glass fibers).
The following solvents were used: 'ethanol; diethyleneglycol, monoglyme,
diglyme,
acetonitrile; acetone; ethylmethylketone; ethylacetate; dimethylsulphoxide;
sulfolane.
The experiment was repeated with another coating solution:
-3.Og coating solution of oleic acid (FA-5) + Epolene wax (POL-5) (80% (wt)
and
20% (wt), respectively).
The following solvents were used: hexane; cyclohexane; toluene; acetonitrile;
acetone; ethylmethylketone; ethylacetate.
The results obtained were practically similar to those obtained above.
AMENOED 5AET
CA 02230892 1998-03-24 T~~~ 6 J O O U / L
~tAvU~ o g Str ' 77
26
Example 4
Production of Surface Coated Calcium Carbonate
CaCO3 powder (d50=5 microns) of Polychrom, Israel- "Girulite-10" were coated
by
several coating solutions as follows:
400g calcium carbonate and 200g water were mixed in a Retch KM-1 mixer and the
following materials were introduced:
1. Ca(OH)Z powder until the pH reached the range of 9.0-9.5
2. 4g MgSO4 brine
3. A coating solution, as specified in Table 2:
~"' Table 2
Weight (g) Type of Material
Test # CaCO3 Water FA POL FA POL
16 400 200 4.0 1.0 1 3
17 400 200. 4.0 1.0 2 4
18 400 200 3.0 1.0 7 5
19 400 200 3.0 1.0 5 5
20 400 200 3.0 1.0 6 5
21 400 200 30.0 100.0 8 6
The slurry was further mixed for 5 mins. The products were then filtered off
and dried at
110oC for 15 hrs. The dry products were disintegrated to powders and subjected
to the
Modified Hallimond Tube test (a well known floatability tests - cf. "Mineral
Processing"; E. J. Pryor; Third Ed.; Elsevier Publishing Co.; 1965; pp. 463-
468) to
check the quality of coating obtained. All the sample tested were found to be
100%
hydrophobic.
IENDED 9FKT
CA 02230892 1998-03-24 PIL 96I ~ ~ U'l~,S
IPEAIUS 0 $ SEP '97 ~
27
Example 5
Production of Slow Release Fertilizers
Granules of slow release fertilizers were prepared in three stages as follows:
1. Mixing the fertilizers and other additives in order to produce granules in
order to
produce magnesite cement coated material.
2. Granulation of the above material (of stage 1) and sieving to obtain
granulated
fertilizers of the size of +3.5-2.0 mm.
3. Coating the granules (of stage 2) with coating solutions and hardening it.
Stae 1
The first stage was conducted in a laboratory mixer - Retch type KM-1. The
materials
described in Table 3 and Table 4 constituted the product of this stage:
Table 3
Test # Fertilizer Composition
22 250g K2SO4 + lOg Urea
23 200g KCl + 50g TSP
24 220g MAP + 30g TSP
Tahhe 4
Weight (g)
Test # Fertilize MgC12 MgSO4 CaCOP' FeC13 FeSO4(2) NTAH3 Wate MgO
22 260 20 25 5 0.6 5 25
23 250 25 20 20 0.6 9 20
24 250 20 20 10 0.6 10 25
Remarks: (1) CaCO3 powder (d50=18 microns) of Polychrom, Israel- "Girulite-40"
(2) EeS04 'O was used
AMENDED ~ET
--~
CA 02230892 1998-03-24 PCTAL 9 6 ~0 0 0 9 2-
28
Stages 2 & 3
The products of the above stage were sieved and the desired granules were
coated by
spraying them with the suitable coating solutions in a rotating granulating
pan.
Thereafter, the granules were dusted with a fine powder of MgO in the
granulator, where
the chemical reaction with the corresponding carboxylic acid(s) led to the
precipitation
of the carboxylate salt(s) and the coating onto the surface of the fertilizer.
The surface of
the granules became immediately hard and the products were ready for
packaging.
However, the magnesite cement continued to cure for an additional 7 days. The
coating
solutions that were applied (containing 80% (wt) carboxylic acid and 20% (wt)
coating)
are given in Table 5:
Table 5
100g Granules of Coating The Composition of MgO
Test # Fertilizer from Test # Solution (g) the Coating Solution (g)
25 22 8 Tall Oil Acid + Epolene Wax 2.0
26 ' 22 10 Oleic Acid + LDPE 2.0
27 24 6 Oleic Acid + Epolene Wax 2.0
28 24 8 Palmitic Acid + Epolene Wax 2.0
29 25 8 Tall Oil Acid + Epolene Wax 2.0
30 25 10 Tall Oil Acid + LDPE 2.0
The third stage comprised the evaluation of the resulted fertilizers as
follows:
The coated and hardened fertilizers of the previous stage were immersed in
water
( 1:10 wt ratio) at 22 C. After 5 days the water was removed from the wet
fertilizers,
which were then dried at 70 C for 24 hrs. The results are given in Table 6,
which
contains also comparison tests of uncoated fertilizers:
CA 02230892 1998-03-24 PUAL 9 6 I u 0 0 92
29
Table 6
Fertilizer Taken From WW5 Days(2) % Weight
Test # Test # (g) (g) Loss Note
31 22 20 15.0 25.0 Reference
32 23 20 13.0 35.0 Reference
33 24 20 14.0 30.0 Reference
34 25 20 19.8 1.0 Coated Product
35 26 20 19.5 2.5 Coated Product
36 27 20 19.0 5.0 Coated Product
37 28 20 18.5 7.5 Coated Product
38 29 20 19.0 5.0 Coated Product
39 30 20 19.0 5.0 Coated Product
Remarks:
(1) The initial weight of the fertilizer in the test.
(2) The weight of the dry fertilizer after 5 days in water.
Examole 6
Production of Metal Coated Polymer
Raw Materials
-500g LDPE (POL-6)
- 4g coating solution (containing: 3g tall oil acid + lg Epolene wax)
- 1 g aluminum metal powder
- 1 g MgO powder
The LDPE granules were rotated in a granulating pan. Then, the coating
solution was
sprayed onto the LDPE to form a thin adherent layer. Thereafter, the coated
granules
were dusted with the aluminum powder to form a homogeneous metal coating.
'='NDED St~fi
CA 02230892 1998 03 24 PUAL 9 6 f0o~9'Z
Eventually, the MgO fine powder was dusted on top of the granules, which
caused the
immediate hardening of the coated layer.
At this stage, evenly coated LDPE granules with aluminum were obtained and any
attempt to wipe off the aluminum powder from the granules was futile.
All the above description and examples have been provided for the purpose of
illustration and are not intended to limit the invention. Many modifications
can be
effected in the various procedures, processes and additives, to give a variety
of surface-
modified minerals, all without exceeding the scope of the invention.
AWND9#? 9HW
