CA2047218A1 - Process for producing organized powders by spraying from at least two sets of particles, and organized powders thus obtained - Google Patents
Process for producing organized powders by spraying from at least two sets of particles, and organized powders thus obtainedInfo
- Publication number
- CA2047218A1 CA2047218A1 CA 2047218 CA2047218A CA2047218A1 CA 2047218 A1 CA2047218 A1 CA 2047218A1 CA 2047218 CA2047218 CA 2047218 CA 2047218 A CA2047218 A CA 2047218A CA 2047218 A1 CA2047218 A1 CA 2047218A1
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- particles
- process according
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- organized
- core
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K9/00—Medicinal preparations characterised by special physical form
- A61K9/14—Particulate form, e.g. powders, Processes for size reducing of pure drugs or the resulting products, Pure drug nanoparticles
- A61K9/16—Agglomerates; Granulates; Microbeadlets ; Microspheres; Pellets; Solid products obtained by spray drying, spray freeze drying, spray congealing,(multiple) emulsion solvent evaporation or extraction
- A61K9/167—Agglomerates; Granulates; Microbeadlets ; Microspheres; Pellets; Solid products obtained by spray drying, spray freeze drying, spray congealing,(multiple) emulsion solvent evaporation or extraction with an outer layer or coating comprising drug; with chemically bound drugs or non-active substances on their surface
- A61K9/1676—Agglomerates; Granulates; Microbeadlets ; Microspheres; Pellets; Solid products obtained by spray drying, spray freeze drying, spray congealing,(multiple) emulsion solvent evaporation or extraction with an outer layer or coating comprising drug; with chemically bound drugs or non-active substances on their surface having a drug-free core with discrete complete coating layer containing drug
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
- B01J2/02—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops
- B01J2/04—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops in a gaseous medium
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/20—Compounding polymers with additives, e.g. colouring
- C08J3/205—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase
- C08J3/21—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase the polymer being premixed with a liquid phase
- C08J3/215—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase the polymer being premixed with a liquid phase at least one additive being also premixed with a liquid phase
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
- C09C1/0081—Composite particulate pigments or fillers, i.e. containing at least two solid phases, except those consisting of coated particles of one compound
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
- C09C1/0081—Composite particulate pigments or fillers, i.e. containing at least two solid phases, except those consisting of coated particles of one compound
- C09C1/0084—Composite particulate pigments or fillers, i.e. containing at least two solid phases, except those consisting of coated particles of one compound containing titanium dioxide
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/30—Particle morphology extending in three dimensions
- C01P2004/32—Spheres
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/10—Solid density
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
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- Crystallography & Structural Chemistry (AREA)
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Abstract
Process for producing organized powders by spraying from at least two sets of particles, and organized powders thus obtained.
Invention: Alain MEYBECK
Philippe ANTOINE
L V M H RECHERCHE
ABSTRACT OF THE DISCLOSURE
The invention relates to a process for producing organized powders.
This process for producing organized powders, obtained from particles of different sizes belonging to at least two sets of particles of substantially homogeneous sizes, comprising respectively at least one set of core particles and at least one set of satellite particles, is characterized in that, in a first step, a substantially homogeneous dispersion of each set is made in a dispersing liquid; and, in a second step, said dispersion is sprayed in suitable conditions to cause the formation of the organized powder.
This process makes it possible to obtain organized powders which are characterized by a very unifor covering oof the core particles whatever their shape, in large quantities and at low costs.
Invention: Alain MEYBECK
Philippe ANTOINE
L V M H RECHERCHE
ABSTRACT OF THE DISCLOSURE
The invention relates to a process for producing organized powders.
This process for producing organized powders, obtained from particles of different sizes belonging to at least two sets of particles of substantially homogeneous sizes, comprising respectively at least one set of core particles and at least one set of satellite particles, is characterized in that, in a first step, a substantially homogeneous dispersion of each set is made in a dispersing liquid; and, in a second step, said dispersion is sprayed in suitable conditions to cause the formation of the organized powder.
This process makes it possible to obtain organized powders which are characterized by a very unifor covering oof the core particles whatever their shape, in large quantities and at low costs.
Description
2~7~
ocess for producing organ _ed powders by spraying from ~t least two sets ~f particles, and organized powders thus obtained.
The present invention relates essentially to a process for producing organized powders from different-sized particles 05 belonging to at least two populations of particles of substantially homogeneous size. It also relates to the organized powders thus obtained.
; In the present document, the expression "organized powder"
designates the regular assembly of particles of different sizes, particles of small sizes, or "satellite particles", which settle in regular order on the surface of a particle of larger size, or "parent" or "core particle", so as to cover up the latter in one or more layers, either partly or completely.
In the prior art, various processes are known for producing organized powders obtained from particles of different sizes. For example, document JP-A-62-083 029 NARA describes a process and a device permitting the preparation of organized powders from two sets of particles of homogeneous sizes by a technique known as percussion impact. In general, the core particles have a mean diameter of about 0.1 ~m to lOû ~m and the satellite particles a mean diameter of about O.Ol,um to 10 ~m. With this process, a good adhesion of the satellite particles to the core particles is obtained, with a substantially uniform covering, the whole constituting a system generally called "hybrid powder".
In addition, various articles have been published in the ; literature concerning organized mixtures. In particular, reference can be made to the revue, Powder Technology 11 (1975) 41-44 or Z5 (1930) 115-119.
However, the techniques used priorly are ~not very satisfactory. In particular, they are complex and costly, hence difficult to use on an industrial scale.
It is therefore the object of the present invention to solve the new technical problem consisting in providing a process for producing organized powders in a simple way, permitting the production of organized powder in reproducible manner, the .. .. ..
., : ,., .:
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. = 2 ~
parameters of which process can be adapted to industrial demand and at a low cost.
This new technical problem is solved for the first time in an extremely simple way by the present invention, which makes it 05 suitable for use on an industrial scale.
Thus, in a first aspect, the present invention provides a process for producing organized powders from particles of different sizes belonging to at least two sets of particles of substantially homogeneous sizes, comprising respectively, at least one SPt of core particles and at least one set of satellite particles of smaller size than that of the core particles, characterized in that in a first step, a substantially homogeneous dispersion of each set is made in a dispersing liquid; and, in a second step, said dispersion is sprayed in suitable conditions to allow the formation of said organized powder.
In the present description and claims, the term "spraying"
should be understood to have a broad meaning, said term notably ; ~ covering the terms "nebuli~ation" and "atomization".
According to a particular embodiment, the spraying of said dispersion is performed inside an enclosure in conditions of pressure and temperature such as to allow the evaporation of the dispersing liquid, thus leading to the formation of said organized powder.
Advantageously, the spraying is performed in~ a gaseous fluid brought to a sufficient temperature to cause the evaporation of the dispersing liquid.
::
The temperature of the gaseous fluid is preferably higher than the boiling point of the dispersing liquid~
In particular, the gaseous fluid is constituted by air.
It will be noted that, obviously, when carrying out the present invention, the dispersing liquid should not be liable to dissolve said particles.
According to a particular variant of embodiment of the process according to the invention, said dispersion is produced in one liquid only.
2 ~
Advantageously, the dispersing liquid is constituted by water or an aqueous solution.
According to annther particular variant oE embodiment, the dispersion of each set is made in one particular dispersing liquid 05 and the two dispersions are thereafter mixed homogeneously either before spraying or at spraying time.
According to another variant of embodiment, a wetting substance, such as a surfactant, for example like the product sold under the denomination TWEEN 20, is added to the dispersing liquid prior to the introduction of the particles, in a concentration of 1% by weight of dry material, i.e. of the totaI quantity of particles to be dispersed.
In general, the dry material content of the dispersing liquid, i.e. the ratio of the quantity by weight of core particles and of satellite particles to the quantity by weight of dispersing liquid, can range between 5 and ~0%, preferably between 10 and 20%, and preferably still between 10 and 15%.
According to a particular characteristic, the mean diameter of the satellite particles is advantageously less than or ~ ~ 2û equal to about one fifth of the mean diameter of the core ; particles.
According to another characteristic, the relative proportion by weight of the satellite particles relatively to the core particles, may vary within wide limits, and is dependent on the structure wanted for the organized powder.
More precisely, the relative proportion by weight (R) of the satellite particles relatively to the core particles will be determined as a function of the number of satellite~; particles which are expected to adhere to one core particle and of the mean masses of the satellite particles and of the core particles, according to the formula:
nM
R = -Mo . . : . ~ , ,~ . .
: . ' ' ' ' ' , in which n is the mean number of satellite particles adhering to one core particle, M is the mean mass of a satellite particle and Mo is the mean mass of a core particle.
The number of satellite particles adhering to a core 05 particle is essentially dependent on the surface occupied by each satellite particle on a core particle, of the surface occupied on the core particle (covering of the core particle may be partial or total~ and of the number of layers of satellite particles on a core particle (unil3yered or multilayered structure).
In the case of a unilayered structure, and for a total covering of the core particles, the theoretical number of satellite particles liable to adhere to one core particle is equal to the ratio of the total surface of a core particle to the surface occupied by a satellite particle.
This ratio therefore permits a calculation of the theoretical proportion by weight of each one of the two sets of particles, in percentage with respect to the total weight of powder.
For implementing the present invention, the proportions by weight will thus be selected so as to be close to the ~; ~ theoretical values. However, and in particular to allow for a certain variability in the shape of the particles, it will be possible to deviate more or less fro~ said theoretical value in order to obtain the target results.
By way of examples, Table I sums up the theoretical caIculation of the relative proportion by weight (or by mass) of the satellite particles relatively to the core particles in the two most common cases, where the satellite particles are substantially spherical-shaped and the core particles are substantially spherical-shaped or cylindrical-shaped such as a disk.
' In bokh cases, the surface of core particle occupied by asatellite particle has been considered to be substantially equal to the projected surface of said satellite particle, meaning in effect its equatorial surface.
In the case where the core particles are disk-shaped, the , :
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height h of the disk is considered in the calculation as being very small, hence as being negligible with respect to the diameter of the disk.
The general principle of such calculation can be used 05 whatever the geometrical shapes of the satellite particles and of the core particles.
Also, the calculations which are made will allow for the differences in the size of the particles, using for example, mean sizes or mean masses for said particles.
Accordingly9 in a preferred embodiment, the percentage by weight of the satellite particles expressed in relation to the total dry material is preferably close or equal to the theoretical percentage given by the formula :
SopV
C~ X 100 SopV ~ poVoS
in which S, SO~ p, pO, V and VO have the meanings indicated in Table I hereafter.
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According to a particular embodiment, said dispersing liquid contains a binding compound designed to help the satellîte particles to adhere to the core particles.
Advantageously, said binding compound is dissolved in the 05 dispersing liquid which serves as a vector.
According to another variant, the binding compound can be just placed in suspension in the dispersing liquid serving as vector.
Examples of suitable binding campounds are carboxymethylcellulose, hydroxypropylmethylcellulose, methyl-cellulose, polyvinylpyrrolidone, ethylcellulose, hydroxypropyl-cellulose or polymethacrylates.
The binding compound can also be added with plasticizers or antiadhesive agents to prevent the agglomeration of particles of organized powder.
In another variant of embodiment of the process according to the invention, adhesion is achieved bet~een the satellite particles and the core particles by using a material to produce at least one of the sets of particles which can be softened or melted at the temperature of the gaseous fluid used for evaporating the dispersing liquid.
Also, in this case, the temperature of the gaseous fluid, which is higher than the softening temperature of the satellite :
particles and/or core particles, is generally sufficiently high for the evaporation of the dispersing liquid to be quick and complete and for the particles reaching the cyclone of the ` installation to be absolutely dry.
The process according to the inventionn can, for example, be carried out in a conventional evaporation installation comprising a spraying enclosure, connected, on the one hand, to a vat for dispersion of the core particles and of the satellite particles, and, on the other hand, to a cyclone, such as an atomization installation. The dispersion is introduced under pressure (gas compressed under about 3 to 10 bars, and preferably 7 bars) intD the spraying enclosure, for example through the :. : , .:., . .. .. . - ; .
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orifice of a nozzle, the droplets thus obtained being dried with a hot gas ( for example air at about 150-250C).
The present invention also relates, in a second aspect, to the organized powders thus obtained, as well as to the 05 applications of such organized powders which are wellknown to anyone skilled in the art and described in the literature. In particular, said organized powders can be used in the cosmetic, pharmaceutical, phytopathological fields, in the agri-foodstuffs industry, in the fields of pesticides, paints or metallurgy.
By way of examples, the core particles can be constituted by or contain the following products : polyester, polyethylene, polystyrene, polymethylmethacryIate, cellulose, Nylon 6, Nylon 12, Teflon, vinyl chloride or even an epoxy, acrylic or methacrylic resin.
Similarly, the satellite particles can be constituted by or contain the following products: a mineral powder such as for example talc, kaolin, mica, vermiculite, silica; an organic powder such as for example a Nylon or polyethylene powder; a mineral pigment such as for example titanium oxide, zinc oxide, iron oxide, iron titanate, carbon black, manganese purple, chromium oxide, cobalt blue, Prussian blue.
Advantageously, the core particles and the satellite particles are selected from the following couples of sets of particles : Nylon-titanium oxide, Nylon-silica9 Nylon yellow iron oxide, Nylon-cobalt blue, polystyrene-titanium oxide, polyethylene-titanium oxide, polyethylene-yellow iron oxide, polyethylene-black iron oxide, polyethylene-cobalt blue.
Besides the economical advantage, already~ mentioned, over the known processes, the process according to the invention offers many other advantages. For example, it affords the possibility of obtaining a very uniform covering of the core particles whatever their shape, including the strip shapes. It also affords the possibility of very readily producing organized powders constituted of satellite particles and core particles of comparable strength, using a binder if necessary.
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g Other objects, characteris~ics and advantages of the invention will also emerge from the following explanatory description with reference to the examples of embodiment of the invention, which examples are given merely by way of illustration, 05 and which therefore cannot in any way limit the scope of the invention.
Example 1 93 9 of Nylon 12 powder (substantially spherical- or ball-shaped particles) with particles of mean diameter equal to about 5 um and of density about 1.02 g/cm3 are used as core particles, and 7 9 of titanium dioxide (substantially spherical particles) with particles of mean diameter of about 0.02 um and of density about 4 g/cm3 are used as satellite particles.
~ Said two groups of core particles and satellite particles ¦ 15 are placed homogeneously in suspension in an aqueous solution , containing 899 9 of water and 1 g of TWEEN 20.
`I The suspension is then sprayed inside an atomizer, in a gaseous fluid constituted by air heated to a temperature of about 230C, under a pressure of 7 bars for a liquid flowrate of 5 liters per hour.
An organized powder is thus obtained in which the core particles comprise on their surface a plurality of satellite particles. Due to the relative proportion used in the present case, the satellite particles constitute a uniform covering over the surface of the core particles.
Using the experimental protocol described in Example 1, a certain number of organized powders has been produced with , different types of materials being used for the core particles and for the satellite particles, and particularly, by varying the relative proportions by weight of the core particles relatively to the satellite particles.
; The results from these tests are given in Table II and show that the quality of the obtained covering varies from average to excellent, depending on the experimental conditions selected.
In the latter case, the covering obtained is total and ~' :, . . . .
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Example 2 The samP experimental protocol as in Example 1 is used, except that a certain quantity of a binder is introduced in the aqueous dispersing solution.
05 The results obtained are given in Table III in a similar presentation to Table II.
This embodiment makes it possible, in particular, to overcome the disadvantages of the known processes, in those cases where the satellite particles find difficulty in settling on the core particles.
Obviously, the invention covers all the means which constitute technical equivalents of the described means as well as the various combinations thereof.
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.
ocess for producing organ _ed powders by spraying from ~t least two sets ~f particles, and organized powders thus obtained.
The present invention relates essentially to a process for producing organized powders from different-sized particles 05 belonging to at least two populations of particles of substantially homogeneous size. It also relates to the organized powders thus obtained.
; In the present document, the expression "organized powder"
designates the regular assembly of particles of different sizes, particles of small sizes, or "satellite particles", which settle in regular order on the surface of a particle of larger size, or "parent" or "core particle", so as to cover up the latter in one or more layers, either partly or completely.
In the prior art, various processes are known for producing organized powders obtained from particles of different sizes. For example, document JP-A-62-083 029 NARA describes a process and a device permitting the preparation of organized powders from two sets of particles of homogeneous sizes by a technique known as percussion impact. In general, the core particles have a mean diameter of about 0.1 ~m to lOû ~m and the satellite particles a mean diameter of about O.Ol,um to 10 ~m. With this process, a good adhesion of the satellite particles to the core particles is obtained, with a substantially uniform covering, the whole constituting a system generally called "hybrid powder".
In addition, various articles have been published in the ; literature concerning organized mixtures. In particular, reference can be made to the revue, Powder Technology 11 (1975) 41-44 or Z5 (1930) 115-119.
However, the techniques used priorly are ~not very satisfactory. In particular, they are complex and costly, hence difficult to use on an industrial scale.
It is therefore the object of the present invention to solve the new technical problem consisting in providing a process for producing organized powders in a simple way, permitting the production of organized powder in reproducible manner, the .. .. ..
., : ,., .:
. .
. = 2 ~
parameters of which process can be adapted to industrial demand and at a low cost.
This new technical problem is solved for the first time in an extremely simple way by the present invention, which makes it 05 suitable for use on an industrial scale.
Thus, in a first aspect, the present invention provides a process for producing organized powders from particles of different sizes belonging to at least two sets of particles of substantially homogeneous sizes, comprising respectively, at least one SPt of core particles and at least one set of satellite particles of smaller size than that of the core particles, characterized in that in a first step, a substantially homogeneous dispersion of each set is made in a dispersing liquid; and, in a second step, said dispersion is sprayed in suitable conditions to allow the formation of said organized powder.
In the present description and claims, the term "spraying"
should be understood to have a broad meaning, said term notably ; ~ covering the terms "nebuli~ation" and "atomization".
According to a particular embodiment, the spraying of said dispersion is performed inside an enclosure in conditions of pressure and temperature such as to allow the evaporation of the dispersing liquid, thus leading to the formation of said organized powder.
Advantageously, the spraying is performed in~ a gaseous fluid brought to a sufficient temperature to cause the evaporation of the dispersing liquid.
::
The temperature of the gaseous fluid is preferably higher than the boiling point of the dispersing liquid~
In particular, the gaseous fluid is constituted by air.
It will be noted that, obviously, when carrying out the present invention, the dispersing liquid should not be liable to dissolve said particles.
According to a particular variant of embodiment of the process according to the invention, said dispersion is produced in one liquid only.
2 ~
Advantageously, the dispersing liquid is constituted by water or an aqueous solution.
According to annther particular variant oE embodiment, the dispersion of each set is made in one particular dispersing liquid 05 and the two dispersions are thereafter mixed homogeneously either before spraying or at spraying time.
According to another variant of embodiment, a wetting substance, such as a surfactant, for example like the product sold under the denomination TWEEN 20, is added to the dispersing liquid prior to the introduction of the particles, in a concentration of 1% by weight of dry material, i.e. of the totaI quantity of particles to be dispersed.
In general, the dry material content of the dispersing liquid, i.e. the ratio of the quantity by weight of core particles and of satellite particles to the quantity by weight of dispersing liquid, can range between 5 and ~0%, preferably between 10 and 20%, and preferably still between 10 and 15%.
According to a particular characteristic, the mean diameter of the satellite particles is advantageously less than or ~ ~ 2û equal to about one fifth of the mean diameter of the core ; particles.
According to another characteristic, the relative proportion by weight of the satellite particles relatively to the core particles, may vary within wide limits, and is dependent on the structure wanted for the organized powder.
More precisely, the relative proportion by weight (R) of the satellite particles relatively to the core particles will be determined as a function of the number of satellite~; particles which are expected to adhere to one core particle and of the mean masses of the satellite particles and of the core particles, according to the formula:
nM
R = -Mo . . : . ~ , ,~ . .
: . ' ' ' ' ' , in which n is the mean number of satellite particles adhering to one core particle, M is the mean mass of a satellite particle and Mo is the mean mass of a core particle.
The number of satellite particles adhering to a core 05 particle is essentially dependent on the surface occupied by each satellite particle on a core particle, of the surface occupied on the core particle (covering of the core particle may be partial or total~ and of the number of layers of satellite particles on a core particle (unil3yered or multilayered structure).
In the case of a unilayered structure, and for a total covering of the core particles, the theoretical number of satellite particles liable to adhere to one core particle is equal to the ratio of the total surface of a core particle to the surface occupied by a satellite particle.
This ratio therefore permits a calculation of the theoretical proportion by weight of each one of the two sets of particles, in percentage with respect to the total weight of powder.
For implementing the present invention, the proportions by weight will thus be selected so as to be close to the ~; ~ theoretical values. However, and in particular to allow for a certain variability in the shape of the particles, it will be possible to deviate more or less fro~ said theoretical value in order to obtain the target results.
By way of examples, Table I sums up the theoretical caIculation of the relative proportion by weight (or by mass) of the satellite particles relatively to the core particles in the two most common cases, where the satellite particles are substantially spherical-shaped and the core particles are substantially spherical-shaped or cylindrical-shaped such as a disk.
' In bokh cases, the surface of core particle occupied by asatellite particle has been considered to be substantially equal to the projected surface of said satellite particle, meaning in effect its equatorial surface.
In the case where the core particles are disk-shaped, the , :
:' ' '' i , ....... , , , ",. " . , ' i, . :..... ,;
,~, , , i ,, : . . .. .
height h of the disk is considered in the calculation as being very small, hence as being negligible with respect to the diameter of the disk.
The general principle of such calculation can be used 05 whatever the geometrical shapes of the satellite particles and of the core particles.
Also, the calculations which are made will allow for the differences in the size of the particles, using for example, mean sizes or mean masses for said particles.
Accordingly9 in a preferred embodiment, the percentage by weight of the satellite particles expressed in relation to the total dry material is preferably close or equal to the theoretical percentage given by the formula :
SopV
C~ X 100 SopV ~ poVoS
in which S, SO~ p, pO, V and VO have the meanings indicated in Table I hereafter.
:
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, , ', ' ..
.. .
: :
. .
, ~ 21D~72~8 _ .
~Is scl!so ~QI~Q QIQ
~ ~ ~1~
a~
~ ~ ~ o ~ o ~a.
~: : S' Q Q
. _._ ._ o Q C~ ¦~N D
O r-O ~ .Q a, '`
:~ S Q C~ ~
~ . _ C ~ IT~
: ~_ ~ Ul ~o o a) ~ o v~ v~ _ ~ ~ a.
N ~J N t~l~ ~ L _ ~ V~
~` llC~ ~ ~ ~ ~ Q ~ O ,U
C ~ t~l L J -- ~ a.l L U `--Q ~ L . ~ ~ ~ Q U) ~I L
:~ : ` . , - _ ~ .) L ~
: O ~ Q ~ Q 3 al ~ ~ ~ Q .. ..
~ ~ ~ t ~¦~ ~ L ,~ o ~ CJ L ~,, ~ -- o ~ ---- o ~ ~ J L ' 'L
a~ ~ ~ O ~ ~ o .____ .~ _ f~ U O ~ ~
>` O O ~ ~ ~
O N I~J O O Q~ O O O
: ~ v~ ~;: ~ J -- ~ a~ ~ ~ ~ ~ E E
~1 ~ D 1/) U1 1;1 tl) E E ~n u) o : . ~ L- E ul u) _ _ to ~ C c .~ _ o o ~ o o I Q C E E L L
L 11 li 11 11 11 11 11 11 11 11 11 11 ll O L O O O O
a~ Q v V~ V~ C 5~ Q Q _c ~ ~
' . ~ ~1 :~
i :~ '' : ' . . : ''` ,: ' .: , : ' : , ' :. : . . '. . ' : '; . . : ` ', ~ , ' ' ' . " .;. ': ' :: -, :., ' ` ~ ' ' 2~7~
According to a particular embodiment, said dispersing liquid contains a binding compound designed to help the satellîte particles to adhere to the core particles.
Advantageously, said binding compound is dissolved in the 05 dispersing liquid which serves as a vector.
According to another variant, the binding compound can be just placed in suspension in the dispersing liquid serving as vector.
Examples of suitable binding campounds are carboxymethylcellulose, hydroxypropylmethylcellulose, methyl-cellulose, polyvinylpyrrolidone, ethylcellulose, hydroxypropyl-cellulose or polymethacrylates.
The binding compound can also be added with plasticizers or antiadhesive agents to prevent the agglomeration of particles of organized powder.
In another variant of embodiment of the process according to the invention, adhesion is achieved bet~een the satellite particles and the core particles by using a material to produce at least one of the sets of particles which can be softened or melted at the temperature of the gaseous fluid used for evaporating the dispersing liquid.
Also, in this case, the temperature of the gaseous fluid, which is higher than the softening temperature of the satellite :
particles and/or core particles, is generally sufficiently high for the evaporation of the dispersing liquid to be quick and complete and for the particles reaching the cyclone of the ` installation to be absolutely dry.
The process according to the inventionn can, for example, be carried out in a conventional evaporation installation comprising a spraying enclosure, connected, on the one hand, to a vat for dispersion of the core particles and of the satellite particles, and, on the other hand, to a cyclone, such as an atomization installation. The dispersion is introduced under pressure (gas compressed under about 3 to 10 bars, and preferably 7 bars) intD the spraying enclosure, for example through the :. : , .:., . .. .. . - ; .
2~`~7~
orifice of a nozzle, the droplets thus obtained being dried with a hot gas ( for example air at about 150-250C).
The present invention also relates, in a second aspect, to the organized powders thus obtained, as well as to the 05 applications of such organized powders which are wellknown to anyone skilled in the art and described in the literature. In particular, said organized powders can be used in the cosmetic, pharmaceutical, phytopathological fields, in the agri-foodstuffs industry, in the fields of pesticides, paints or metallurgy.
By way of examples, the core particles can be constituted by or contain the following products : polyester, polyethylene, polystyrene, polymethylmethacryIate, cellulose, Nylon 6, Nylon 12, Teflon, vinyl chloride or even an epoxy, acrylic or methacrylic resin.
Similarly, the satellite particles can be constituted by or contain the following products: a mineral powder such as for example talc, kaolin, mica, vermiculite, silica; an organic powder such as for example a Nylon or polyethylene powder; a mineral pigment such as for example titanium oxide, zinc oxide, iron oxide, iron titanate, carbon black, manganese purple, chromium oxide, cobalt blue, Prussian blue.
Advantageously, the core particles and the satellite particles are selected from the following couples of sets of particles : Nylon-titanium oxide, Nylon-silica9 Nylon yellow iron oxide, Nylon-cobalt blue, polystyrene-titanium oxide, polyethylene-titanium oxide, polyethylene-yellow iron oxide, polyethylene-black iron oxide, polyethylene-cobalt blue.
Besides the economical advantage, already~ mentioned, over the known processes, the process according to the invention offers many other advantages. For example, it affords the possibility of obtaining a very uniform covering of the core particles whatever their shape, including the strip shapes. It also affords the possibility of very readily producing organized powders constituted of satellite particles and core particles of comparable strength, using a binder if necessary.
:: . . ~:: . : : :
~7~
g Other objects, characteris~ics and advantages of the invention will also emerge from the following explanatory description with reference to the examples of embodiment of the invention, which examples are given merely by way of illustration, 05 and which therefore cannot in any way limit the scope of the invention.
Example 1 93 9 of Nylon 12 powder (substantially spherical- or ball-shaped particles) with particles of mean diameter equal to about 5 um and of density about 1.02 g/cm3 are used as core particles, and 7 9 of titanium dioxide (substantially spherical particles) with particles of mean diameter of about 0.02 um and of density about 4 g/cm3 are used as satellite particles.
~ Said two groups of core particles and satellite particles ¦ 15 are placed homogeneously in suspension in an aqueous solution , containing 899 9 of water and 1 g of TWEEN 20.
`I The suspension is then sprayed inside an atomizer, in a gaseous fluid constituted by air heated to a temperature of about 230C, under a pressure of 7 bars for a liquid flowrate of 5 liters per hour.
An organized powder is thus obtained in which the core particles comprise on their surface a plurality of satellite particles. Due to the relative proportion used in the present case, the satellite particles constitute a uniform covering over the surface of the core particles.
Using the experimental protocol described in Example 1, a certain number of organized powders has been produced with , different types of materials being used for the core particles and for the satellite particles, and particularly, by varying the relative proportions by weight of the core particles relatively to the satellite particles.
; The results from these tests are given in Table II and show that the quality of the obtained covering varies from average to excellent, depending on the experimental conditions selected.
In the latter case, the covering obtained is total and ~' :, . . . .
: . . , :: :
,. . , -,, " , . . .... .
o ~72 oC~y ~ ~ ~ ~ ~ #
u~ * # ~ ~ I ~
:~ _ _ __ _ aJ
, ~ o o o I o oo ~ ~N ~ l l l N
N .--_ _ _ O .~ .~ .~ .~ I ~ ~ ' ~ cn ~ ~ Il~ (1~ n~ ~ 111 ... ____ __ _ . .-C ~ ~ ~ ~ ~ ~ ~ ~ .
~0 ~0 ~0 ~ ~0 : _ ..
:~: ,c~.~ C
~1 ~ ~ _ ON TN IN OIN o~ OIN OTN
,_1 '~ ~
`: ~ _ _ _ _ ~ ~ ~ ;~s ~ 0~ ~ O~o a~ 0~ ;~ 0~ o ~ a~o 3 `' o~ o~ u~ ~ ~ ~o o ~ ~o ~ ~o ~
C~
_ ~ N N ~.
O N ~ o ~ oO . N . O N 11~
I~ OIl~ O `O O. O ~ O ~ O ~ o ~n ~~ u~ u~ ~ ~~ ~ u)_ u~_ Q O_ ____ u~_u~-- __ _ ~
: E 1~ ~ ~ ~ ~~ ~ ~ ~ D "~ .23 ~ ~ Q
_ __ _ _ - : I O N ~ O _ IIJ X
:: Q ~ Q ~ C _ ~ 1-_ C _ N NN ~J CJ N ~J N _ N ~, : . CJ ,_ g.- CC ~~ '5: ~- ~ ~
~ C oN_ O >~ oNC O~ C oN J oN --Z z>~ ~_ Z~ Q 'l- Z>` '~ ~ Q 'l- ~
_ _ . _ _ c~ c~ c~ a a ~ a~
., u ~ ., ~. ., ., .~ ., ., .~ .~ .~ .~
~ G~ ~ a a, ~ ~
'~ ~ ., '~ ~ '~ ~ '~- aJ '~ a~ '~ aJ
Q _Q _L ~ Q _ L ~ Q _J Q _ ~ c~a., ~, a, ~, a~ aJ a, a) ~
_ v~ 0~0~ ~n 0~0~ 0~
: , '', ' ~'. "`' ."' '; : ' ' ' ` '~:
~, . . ..
11 2~72~8 ~ ~ ~ ~ c ~ U V) # ~ # #
~o O #
~,0~ ~ ~ ., o ~n . ..
~ ~ . ~
cn .~ .
: O- _ .
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C Q~ _ t~l ~, , Ul V) I I
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:~ 3 D ~0 ~ O ~ Ql C
.~ _--0(~1 1~ C
~ ~ U~O ~-~ ~ + ~, t_ ~ Cl Q ~ D L _ ~ C
0_~ C~ ~ _ _ Q v ~
~ O >~ ~ 'O O ~ ~ 2~
_ Z 2 0~ ~ .s~ ,Cn ,cn ~
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~ ., ~ ~ D
L~ ~ _ Q l >~ >~ .
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o o o ~ 11 11 ~_ ~ ~)~
:, ~ ,. .~ : .
': , ' : ~ :
Example 2 The samP experimental protocol as in Example 1 is used, except that a certain quantity of a binder is introduced in the aqueous dispersing solution.
05 The results obtained are given in Table III in a similar presentation to Table II.
This embodiment makes it possible, in particular, to overcome the disadvantages of the known processes, in those cases where the satellite particles find difficulty in settling on the core particles.
Obviously, the invention covers all the means which constitute technical equivalents of the described means as well as the various combinations thereof.
~ .
: ~ :
f ~ ~''' ~ ` . ' ' .
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13 2~72~
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O
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,_, ;~! ~! ;#~ ~
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_ ~ I'~
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~ _~ o ~ o 3 0 ~ o ~ .
UO~
c ~ ~ ~ ~ c ~ ~ O a _ _ ,~, ~ ~ ~ _ _ ~ ' a, ~ ~ V ~ ,, ~ ~ ~ ~,,, _ f:J~ _ S C -- J C -- SQJ J S C~ E
~ >` ,Q ,4 S ~ ~L >` D ~ ~ _ _ _ Q u ~ O ~ ~ ~ I Q O I ~ L
CJ U (IJ ~ ~J ~X~
., _ (~J _ ITJ ~IJ L a, ~ O
(_~ Q 1~ Q (~ Q ~J Q O ~ ::~
L ~J r .~, ~ ., Q -- ~ Q -- C_ Q -- L Q -- ~ ~ <_~ ~
L. ~ ~ L. ~ ~L. ~ ~ L. ~ C S :~:
v~ m ~ ~'m o fa, o lo, ;' , - :
.
Claims (15)
1. Process for producing organized powders obtained from particles of different sizes belonging to at least two sets of particles of substantially homogeneous sizes comprising, respectively, at least one set of core particles and at least one set of satellite particles, characterized in that, in a first step, a substantially homogeneous dispersion of each set is made in a dispersing liquid; and, in a second step, said dispersion is is sprayed in suitable conditions to allow the formation of said organized powder.
2. Process according to claim 1, characterized in that the spraying of said dispersion is performed inside an enclosure in conditions of pressure and temperature such as to obtain the formation of said organized powder.
3. Process according to claim 1 or 2, characterized in that the spraying of said dispersion is performed in a gaseous fluid brought to a sufficient temperature to cause the evaporation of the dispersing liquid.
4. Process according to one of claims 1 to 3, characterized in that the dispersion is produced in only one liquid.
5. Process according to one of claims 1 to 4, characterized in that the dispersing liquid is constituted by water or an aqueous solution.
6. Process according to one of claims 1 to 5, characterized in that the gaseous fluid is constituted by air.
7. Process according to one of claims 1 to 6, characterized in that the mean diameter of the satellite particles is less than or equal to about one fifth of the mean diameter of the core particles.
8. Process according to any one of the preceding claims, characterized in that it comprises, prior to the introduction of the particles, the addition to the dispersing liquid, of an efficient quantity of wetting substance, such as a surfactant.
9. Process according to one of the preceding claims, characterized in that the percentage by weight of the satellite particles expressed with respect to the total dry material is preferably close or equal to the theoretical percentage given by the formula:
in which S is the portion of surface of core particle occupied by a satellite particle, So is the total surface of a core particle, is the density of the satellite particles, o is the density of the core particles, V is the volume of a satellite particle and Vo is the volume of a core particle.
in which S is the portion of surface of core particle occupied by a satellite particle, So is the total surface of a core particle, is the density of the satellite particles, o is the density of the core particles, V is the volume of a satellite particle and Vo is the volume of a core particle.
10. Process according to one of the preceding claims, characterized in that said dispersing liquid contains at least one binding compound designed to help the satellite particles to adhere to the core particles.
11. Process according to claim 10, characterized in that the binding compound is dissolved in the dispersing liquid serving as a vector.
12. Process according to claim 10, characterized in that the binding compound is constituted by carboxymethylcellulose or by hydroxypropylmethylcellulose.
13. Process according to one of the preceding claims, characterized in that the satellite particles and/or the core particles are constituted in a material which can be softened or melted at the temperature of the gaseous fluid used for evaporating the dispersing liquid.
14. Process according to one of the preceding claims, characterized in that the core particles and the satellite particles are selected from the following couples of sets of particles : Nylon-titanium oxide, Nylon-silica, Nylon-yellow iron oxide, Nylon-cobalt blue, polystyrene-titanium oxide, polyethylene-yellow iron oxide, polyethylene-black iron oxide, polyethylene-cobalt blue.
15. Organized powder, characterized in that it is obtained by the process such as defined according to any one of claims 1 to 14.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8910565 | 1989-08-04 | ||
| FR8910565A FR2650514B1 (en) | 1989-08-04 | 1989-08-04 | METHOD FOR MANUFACTURING ORDERED POWDERS BY SPRAYING FROM AT LEAST TWO PARTICLE POPULATIONS, AND ORDERED POWDERS THUS OBTAINED |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2047218A1 true CA2047218A1 (en) | 1991-02-05 |
Family
ID=9384501
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2047218 Abandoned CA2047218A1 (en) | 1989-08-04 | 1990-08-03 | Process for producing organized powders by spraying from at least two sets of particles, and organized powders thus obtained |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPH084738B2 (en) |
| CA (1) | CA2047218A1 (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6283029A (en) * | 1985-10-07 | 1987-04-16 | Nara Kikai Seisakusho:Kk | Method and apparatus for surface modification of solid particle |
-
1990
- 1990-08-03 JP JP2511785A patent/JPH084738B2/en not_active Expired - Lifetime
- 1990-08-03 CA CA 2047218 patent/CA2047218A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| JPH084738B2 (en) | 1996-01-24 |
| JPH04501531A (en) | 1992-03-19 |
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