WO2014033187A1

WO2014033187A1 - Finely divided particles of core-shell structure

Info

Publication number: WO2014033187A1
Application number: PCT/EP2013/067850
Authority: WO
Inventors: Wolfgang Gerlinger; Bernd Sachweh; Michael Wörner; Ertan AKGÜN; Stephanie SIGMUND; Gerhard Kasper
Original assignee: Basf Se; Karlsruher Institut für Technologie; Basf Schweiz Ag
Priority date: 2012-08-30
Filing date: 2013-08-28
Publication date: 2014-03-06
Also published as: EP2890487A1; CN104768639A; CA2883037A1; JP2015530434A

Abstract

The invention provides a process for producing finely divided particles of core-shell structure where the shell comprises at least one polymer, said process comprising the steps of: i. providing a first aerosol stream of droplets in a carrier gas stream wherein the droplets comprise at least one monomer and charging droplets of the first aerosol with electric charge; ii. providing a second aerosol stream of solid particles in a carrier gas stream and charging the solid particles of the aerosol with an electric charge opposite to the electric charge on the droplets of the first aerosol stream; iii. mixing the first aerosol stream with the second aerosol stream to form a mixed aerosol stream; iv. initiating a polymerization of the monomers by irradiating this mixed aerosol stream with electromagnetic radiation. The invention also provides the finely divided particles of core-shell structure which are obtainable by this process.

Description

Finely divided particles with core-shell structure

The present invention relates to a process for producing finely divided particles having a core-shell structure whose shell comprises at least one polymer. The invention also relates to the finely divided particles having a core-shell structure obtainable by this process as such. The targeted formation and structuring of finely divided composite particles, d. H. Particles having a multiphase morphology, in particular particles having a core-shell structure or core-shell morphology, is of particular interest for the targeted production of particles with special properties for highly specialized applications. Coated finely divided particles having a core-shell structure are of interest for numerous applications, for example in dye compositions or as catalysts. The polymer coating prevents agglomeration of the particles, resulting in higher color intensity or improved catalyst performance. In the medical field marker substances are polymer coated to suppress harmful effects of the particles on the organism. Furthermore, the polymer coating, the protection of the core material from external influences such as corrosion, oxidation, reduction, water u. a., serve. In addition, properties such as the conductivity of coated particles can be modified. Possible here are, for example, finely divided particles with a core-shell structure as hybrid materials for printed electronics, consisting of semiconducting or conducting polymers with semiconductive or conductive inorganic particles. Thus, there is a wide field of application for finely divided particles with core-shell structure in optical, electronic, chemical, biotechnological and medical systems.

Numerous methods for the production of composite particles are known from the prior art. Particularly noteworthy here are the processes in the liquid phase, such as the stepwise emulsion polymerization, the emulsion polymerization in a suspension of non-polymerizable particles or in an emulsion of nonpolymerizable droplets, microencapsulation by coacervation and the like, and processes in the gas phase, eg. As the photo-induced or chemically induced vapor deposition.

Zhang et al., J. Nanopart. Res 2008, 10, 173-178, describe the coating of sodium chloride nanoparticles by photoinduced chemical vapor deposition; AM Boies et al., Nanotechnology 2009, 20, 29, 295604, describe the Production of inorganic core-shell particles by means of chemical vapor deposition.

J.F. Widmann et al., J. Colloid Interface Sei. 1998, 199, 197-205, describe a method by which an isolated microparticle is captured in an electrodynamic trap and contacted with a monomer droplet. The resulting liquid nanoparticle coating is polymerized photochemically.

The processes known from the prior art for the preparation of finely divided composite particles have a number of disadvantages. For one thing, the composite particles are predominantly very uneven, i. that is, there is a broad particle size distribution, uneven particle shape, or uneven particle composition. Many finely divided composite particles do not have a pronounced core-shell morphology, but only attachment structures. Also, only certain particle size ranges can be achieved with the known methods, and in many of the known methods, small particles can only be produced to a limited extent or not at all.

Known gas phase processes for the production of core-shell particles are usually limited to certain particle-monomer combinations. Another disadvantage of the liquid-phase process is the use of emulsifiers, which are undesirable for many applications and often can not be separated. In addition, many of the known processes for producing finely divided composite particles are not suitable for large-scale use because of their low throughput. The object of the present invention is to provide a process for the preparation of finely divided core-shell particles, which overcomes the disadvantages of the prior art. In particular, the method should allow a high throughput, allow the abandonment of the use of surfactants such as emulsifiers and surfactants and can be applied to numerous core and monomer materials.

This object is achieved, surprisingly, by a process for producing finely divided particles having a core-shell structure, the shell of which comprises at least one polymer, the process comprising the steps i. to iv. in which two mutually charged aerosol streams are mixed together, the first aerosol stream containing polymerizable monomers and the second aerosol stream containing solid particles, and then photochemically initiating a polymerization. In this way, particles are obtained with core-shell structure, wherein the particles of the second aerosol stream form the core and the polymerized monomers of the first aerosol stream form a polymeric shell.

The invention therefore relates to the method described here and below, which comprises the steps:

i. Providing a first aerosol stream of droplets in a carrier gas stream, the droplets containing at least one monomer, and charging the droplets of the first aerosol with electrical charge;

ii. Providing a second aerosol stream of solid particles in a carrier gas stream, and charging the solid particles of the aerosol with an electrical one

Charge opposite to the electric charge of the droplets of the first aerosol stream;

iii. Mixing the first aerosol stream with the second aerosol stream into a mixed aerosol stream;

iv. Initiating polymerization of the monomers by irradiating this mixed aerosol stream with electromagnetic radiation.

Advantages of the method according to the invention are firstly a high product purity, since no surface-active substances such as emulsifiers or surfactants have to be added. Furthermore, no addition of a solvent is required. If the particles of the second aerosol stream act as a photoinitiator or if high-energy radiation is used, no photoinitiator has to be added to the monomers. The inventive method allows the simultaneous coating of a variety of particles. The method can be applied to a variety of solid core particles since it is charged oppositely in charging and coagulation

Droplets and particles are a purely physical process. The finely divided core-shell particles obtainable according to the invention exhibit a particularly uniform core-shell structure. A further advantage of the method according to the invention is that the electrostatic charging of the solid particles and droplets avoids coagulation of the particles or droplets among one another, ie within the two aerosol streams, due to charges of the same name. In this way, a narrower particle size distribution and thus better reproducibility of the resulting core-shell particles can be achieved with the method according to the invention. Another advantage of the method according to the invention over methods with thermally induced polymerization is that heating can be dispensed with. Due to the necessary heating during the thermally induced polymerization, the monomers partially evaporate, so that the adjustment of the particle diameter and the shell thickness is complicated and often not reproducible, and optionally only an incomplete coating is achieved. In contrast, the thickness of the polymer shell can be easily adjusted by varying the droplet size in the first aerosol stream and by the ratio of the mass flows in the aerosol streams using the method according to the invention.

The structure of the finely divided core-shell particles obtained after the photopolymerization can be determined by varying the process parameters, such as droplet size of the first aerosol stream, number of charges on the droplets or particles, particle and droplet concentration, geometry and length of the mixing zone, residence time in the Any existing non-illuminated dwell zone, set by the skilled person to the desired result.

According to the invention, the particles produced contain at least one polymer, which is to be understood in the sense of the invention as a homopolymer and / or copolymer. The term "homopolymer" is to be understood as meaning a polymer which is composed of the same monomers The term "copolymer" is to be understood as meaning a polymer which is composed of at least two different monomers.

In general, all monomers which can be polymerized under the action of electromagnetic radiation can be used in the first aerosol stream of the process according to the invention. These are in particular olefinically unsaturated monomers and cyclic, a photochemically induced ring-opening polymerization accessible monomers. The monomers of the first aerosol stream may, for example, be neutral, acidic, basic or cationic.

Preferably, the monomers are selected from olefinically unsaturated monomers, ie, monomers containing at least one, e.g. B. one, two, three or four, C = C double bonds, with particular preference being given to those monomers in which the C = C double bond in the form of a vinylic double bond, ie a singly substituted double bond, or a vinylidene double bond, ie a doubly substituted double bond in which the two substituents are bonded to the same carbon atom of the C = C double bond. Particularly preferred are olefinically unsaturated monomers in which the double bond is in conjugation to a non-polymerizable double bond, for. In conjugation to a carbonyl group, a nitrile group or an aromatic ring, e.g. B. benzene ring, imidazole ring or pyridine ring. Preferably, the at least one monomer is selected from monoolefinically unsaturated monomers and in particular from mixtures of at least one monoolefinically unsaturated monomer with at least one poly-olefinically unsaturated monomer.

In a preferred embodiment of the invention, the first aerosol stream used in the process according to the invention comprises, in addition to the at least one monomer, at least one polyunsaturated monomer (crosslinker). The polyunsaturated monomers cause crosslinking in the polymerization reaction of the monomers provided and thus an increase in the molecular weight of the polymers obtained. The at least one crosslinker is used, for example, in an amount of from 1 to 80% by weight, preferably from 2 to 20% by weight, particularly preferably from 3 to 15% by weight, based in each case on the total amount of olefinically unsaturated monomers.

In a further preferred embodiment of the invention, the at least one monomer used in the first aerosol stream of the process according to the invention comprises essentially exclusively at least one poly olefinically unsaturated monomer (crosslinker). In this embodiment, the at least one poly olefinically unsaturated monomer is generally present in an amount of from 80 to 100% by weight, preferably from 90 to 100% by weight, particularly preferably from 97 to 100% by weight, based in each case on the total amount the olefinically unsaturated monomers used. Preferably, at least 90% by weight of the monomers present in the aerosol stream are selected from neutral olefinically unsaturated monomers.

Suitable according to the invention, neutral monoolefinically unsaturated monomers are generally selected from monoolefinically unsaturated C3-C6 monocarboxylic acids, monoolefinically unsaturated C4-C6 dicarboxylic acids, esters of monoolefinically unsaturated C3-C6 monocarboxylic acids, esters of monoolefinically unsaturated C4-C6 dicarboxylic acids, amides monoolefinically unsaturated C3-C6 monocarboxylic acids, N-vinyl amides, N-vinyl lactams, vinyl aromatics, vinyl ethers, vinyl, allyl and methallyl esters, monoolefinically unsaturated nitriles, α-olefins, monoolefinically unsaturated sulfonic acids, monoolefinically unsaturated phosphonic acids and monoolefinically unsaturated Phosphorsäurehalbestern, in particular under neutral monoethylenically unsaturated monomers from the groups of esters of monoolefinically unsaturated C3-C6 monocarboxylic acids, esters of monoolefinically unsaturated C4-C6 dicarboxylic acids, amides monoolefinically unsaturated C3-C6 monocarboxylic acids, ethylenically unsatured saturated nitric vinyl ethers and mixtures thereof with one or more acidic monomers such as monoolefinically unsaturated C 3 -C 6 -monocarboxylic acids, monoolefinically unsaturated C 4 -C 6 -dicarboxylic acids, monoolefinically unsaturated sulfonic acids, monoolefinically unsaturated phosphonic acids and monoolefinically unsaturated phosphoric acid semiesters.

Examples of neutral monoolefinically unsaturated monomers suitable according to the invention are, in particular, the monomers of the following groups M1 to M12, in particular those of the groups M1, M2, M4, M6, M7, M8, M9, M10 and M12, especially those of the groups M1, M2 , M6, M7, M8, M9 and M10:

M1 esters of monoolefinically unsaturated C3-C6 monocarboxylic acids with C1-C20-

Alkanols, Cs-Cs-cycloalkanols, phenyl-Ci-C4-alkanols or phenoxy-Ci-C ₄ - alkanols, in particular the aforementioned esters of acrylic acid and the aforementioned esters of methacrylic acid, for example methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n Butyl acrylate, 2-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, 3-propylheptyl acrylate, decyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, benzyl acrylate, 2-phenylethyl acrylate, 1-phenylethyl acrylate, 2-phenoxyethyl acrylate, and the esters of methacrylic acid, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, 2-butyl methacrylate,

Isobutyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-phenylethyl methacrylate, 1-phenylethyl methacrylate and 2-phenoxyethyl methacrylate;

M2 diesters of monoolefinically unsaturated C ₄ -C 6 -dicarboxylic acids with C 1 -C 20 -alkanols, C ₃ -C 8 -cycloalkanols, phenyl-C 1 -C ₄ -alkanols or phenoxy-C 1 -C ₄ -alkanols, in particular the abovementioned diesters of maleic acid and the diesters the fumaric acid, in particular di-C 1 -C 20 -alkyl maleates and di-C 1 -C 20 -alkyl fumarates such as dimethyl maleate, diethyl maleate, di-n-butyl maleate, dimethyl fumarate, diethyl fumarate and di-n-butyl fumarate;

M3 vinylaromatic hydrocarbons, such as, for example, styrene, vinyltoluenes, tert-butylstyrene, α-methylstyrene and the like, in particular styrene;

M4 vinyl, allyl and methallyl esters of saturated aliphatic C 2 -C 18 monocarboxylic acids, such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl hexanoate, vinyl 2-ethylhexanoate, vinyl laurate and vinyl stearate, and the corresponding allyl and methallyl esters, and

M5 α-olefins having 2 to 20 C atoms and cycloolefins having 5 to 10 C atoms such as

Ethene, propene, 1-butene, isobutene, 1-pentene, cyclopentene, cyclohexene and cycloheptene; M6 esters of monoolefinically unsaturated C3-C6 monocarboxylic acids with polyethermonomers, in particular with C 1 -C 20 -alkylpoly-C 2 -C 4 -alkylene glycols, especially with C 1 -C 20 -alkyl-polyethylene glycols, where the alkylpolyalkylene glycol radical usually has a molecular weight in the range of 200 to 5000 g / mol (number average), in particular the aforementioned esters of acrylic acid and the aforementioned esters of methacrylic acid;

M7 monoolefinically unsaturated nitriles such as acrylonitrile or methacrylonitrile,

M8 amides of the abovementioned monoolefinically unsaturated C3-C8 monocarboxylic acids, in particular acrylamide and methacrylamide,

M9 N- (C 1 -C 20 -alkyl) amides and N, N-di- (C 1 -C 20 -alkyl) amides of the abovementioned monoolefinically unsaturated Cs-Cs monocarboxylic acids;

M10 hydroxyalkyl esters of the abovementioned monoolefinically unsaturated Cs-Cs monocarboxylic acids, eg. Hydroxyethyl acrylate, hydroxyethyl methacrylate, 2- and 3-hydroxypropyl acrylate, 2- and 3-hydroxypropyl methacrylate;

M1 1 N-vinylamides of aliphatic C 1 -C 10 -carboxylic acids and N-vinyllactams, such as

N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone and N-vinylcaprolactam;

M12 vinyl ethers of C 1 -C 20 -alkanols, such as methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, benzyl vinyl ether. Examples of acid monoolefinically unsaturated monomers which are suitable according to the invention are, in particular, the monomers of the following groups M13 to M17:

M13 monoolefinically unsaturated C3-C6 monocarboxylic acids such as acrylic acid, methacrylic acid, vinylpropionic acid and ethacrylic acid and monoolefinically unsaturated C4-C6 dicarboxylic acids such as itaconic acid, maleic acid, fumaric acid and citraconic acid and their anhydrides;

M14 monoolefinically unsaturated sulfonic acids, in which the sulfonic acid group is bonded to an aliphatic hydrocarbon radical, and salts thereof, such as vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid,

2-acrylamidoethanesulfonic acid, 2-methacrylamidoethanesulfonic acid,

2-acryloxyethanesulfonic acid, 2-methacryloxyethanesulfonic acid,

3-acryloxypropanesulfonic acid and 2-methacryloxypropanesulfonic acid and their salts,

M15 vinylaromatic sulfonic acids, ie monoolefinically unsaturated sulfonic acids in which the sulfonic acid group is bonded to an aromatic hydrocarbon radical, in particular to a phenyl ring, and salts thereof, for example styrenesulfonic acids such as 2-, 3- or 4-vinylbenzenesulfonic acid and salts thereof, M16 monoolefinically unsaturated phosphonic acids in which the phosphoric acid group is bonded to an aliphatic hydrocarbon radical, and salts thereof, such as vinylphosphonic acid, 2-acrylamido-2-methylpropanephosphonic acid, 2-methacrylamido-2-methylpropanephosphonic acid,

2-acrylamidoethane phosphonic acid, 2-methacrylamidoethane phosphonic acid,

2-acryloxyethanephosphonic acid, 2-methacryloxyethanephosphonic acid,

3-acryloxypropanephosphonic acid and 2-methacryloxypropanephosphonic acid and salts thereof,

M17 monoolefinically unsaturated phosphoric monoesters, in particular the half esters of phosphoric acid with hydroxy-C 2 -C 4 -alkyl acrylates and hydroxy-C 2 -C 4 -alkyl methacrylates, for example 2-acryloxyethyl phosphate,

2-methacryloxyethyl phosphate, 3-acryloxypropyl phosphate,

3-methacryloxypropyl phosphate, 4-acryloxybutyl phosphate and

4-methacryloxybutyl phosphate and its salts.

Examples of basic and cationic monoolefinically unsaturated monomers which can be used in the first aerosol stream of the process according to the invention are the monomers of the following groups M18 to M21:

M18 vinyl heterocycles such as 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine and N-vinylimidazole;

M19 Quaternized vinyl heterocycles such as 1-methyl-2-vinylpyridinium salts, 1-methyl-2-vinylpyridinium salts, 1-methyl-4-vinylpyridinium salts, and N-methyl-N'-vinylimidazolium salts, e.g. The chlorides or methosulfates;

M20 N, N- (di-C ₁ -C 10 -alkylamino) C ₂ -C 4 -alkylamides and N, N- (di-C ₁ -C 10 -alkylamino) C ₂ -C ₄ -alkyl esters of the abovementioned monoolefinically unsaturated C ₃ -C 8 -hydrocarbons Monocarboxylic acids, eg. B. 2- (N, N-dimethylamino) ethylacrylamide,

2- (N, N-dimethylamino) ethylmethacrylamide, 2- (N, N-dimethylamino) propylacrylamide, 2- (N, N-dimethylamino) propylmethacrylamide, 3- (N, N-dimethylamino) propylacrylamide, 3- (N, N-Dimethylamino) propylmethacrylamide, 2- (N, N-diethylamino) ethylacrylamide, 2- (N, N-diethylamino) ethylmethacrylamide, 2- (N, N-diethylamino) propylacrylamide, 2- (N, N diethylamino) propyl methacrylamide,

3- (N, N-diethylamino) propylacrylamide, 3- (N, N-diethylamino) propylmethacrylamide,

2- (N, N-dimethylamino) ethyl acrylate, 2- (N, N-dimethylamino) ethyl methacrylate, 2- (N, N-dimethylamino) propyl acrylate, 2- (N, N-dimethylamino) propyl methacrylate, 3- (N, N Dimethylamino) propyl acrylate, 3- (N, N-dimethylamino) propyl methacrylate, 2- (N, N-diethylamino) ethyl acrylate, 2- (N, N-diethylamino) ethyl methacrylate, 2- (N, N-diethylamino) propyl acrylate, 2 - (N, N-diethylamino) propyl methacrylate,

3- (N, N-diethylamino) propyl acrylate and 3- (N, N-diethylamino) propyl methacrylate; M21 N, N- (tri-C 1 -C 10 -alkylammonium) C 2 -C 4 -alkylamides and N, N- (tri-C 1 -C 4 -alkylammonium) C 2 -C 4 -alkyl esters of the abovementioned monoolefinically unsaturated C 3 -C 8 -monocarboxylic acids, eg 2- (N, N, N-trimethylammonium) ethylacrylamide,

2- (N, N, N-trimethylammonium) ethylmethacrylamide, 2- (N, N, N-trimethylammonium) propylacrylamide, 2- (N, N, N-trimethylammonium) propylmethacrylamide,

3- (N, N, N-trimethyl ammonium) propyl acrylamide, 3- (N, N, N-trimethyl ammonium) propyl methacrylamide, 2- (N, N, N-triethyl ammonium) ethyl acrylamide,

2- (N, N, N-triethylammonium) ethylmethacrylamide, 2- (N, N, N-triethylammonium) -propylacrylamide, 2- (N, N, N-triethylammonium) propylmethacrylamide,

3- (N, N, N-triethylammonium) propylacrylamide, 3- (N, N, N-triethylammonium) propylmethacrylamide, 2- (N, N, N-trimethylammonium) ethylacrylate, 2- (N, N, N-trimethylammonium ) ethyl methacrylate, 2- (N, N, N-trimethyl ammonium) propyl acrylate, 2- (N, N, N-trimethyl ammonium) propyl methacrylate, 3- (N, N, N-trimethyl ammonium) propyl acrylate, 3- (N , N, N-trimethylammonium) propyl methacrylate, 2- (N, N, N-triethylammonium) ethyl acrylate, 2- (N, N, N-triethylammonium) ethyl methacrylate, 2- (N, N, N-triethylammonium) propyl acrylate, 2 - (N, N, N-triethylammonium) propyl methacrylate, 3- (N, N, N-triethylammonium) propyl acrylate and 3- (N, N, N-triethylammonium) propyl methacrylate, especially their chlorides, methosulfates and ethosulfates.

Polyolefinically unsaturated compounds (crosslinkers) are, for example, divinylbenzenes, diesters and triesters of olefinically unsaturated carboxylic acids, in particular the bis- and trisacrylates of diols or polyols having 3 or more OH groups, eg. As the bisacrylates and the bismethacrylates of ethylene glycol, diethylene glycol, triethyl englykol, neopentyl glycol or polyethylene glycols, 1, 6-hexanediol diacrylate (HDDA), allyl methacrylate (AMA) and trimethylolpropane trimethacrylate (PMPTMA).

In the process according to the invention, suitable monomers are also saturated cyclic compounds which can be polymerized by a photochemically initiated ring-opening polymerization. Examples of such monomers are cyclic ethers, such as, for example, epoxides, oxetanes, furans and cyclic acetals, as well as lactones and lactams.

Examples of epoxides are ethylene oxide, propylene oxide, butylene oxide and styrene oxide.

Examples of cyclic ethers are also cyclic acetals, eg. B. substituted or unsubstituted cyclic acetals having a ring size of 5 or 6 carbon atoms derived from aldehydes having generally 1 to 10 carbon atoms. These include above all trioxane, 1, 3-dioxane and 1, 3-dioxolane. Examples of cyclic ethers are also substituted or unsubstituted cyclic monoethers having a ring size of 4 or 5 atoms (oxetanes and furans) which generally have 3 to 10 carbon atoms, for example oxetane, 3,3-dimethyloxetane, tetrahydrofuran, 3 Methyltetrahydrofuran, 3,3-dimethyltetrahydrofuran or 3,4-dimethyltetrahydrofuran.

Lactones suitable according to the invention are, for example, substituted or unsubstituted lactones having a ring size of 4, 5, 6 or 7 atoms and having generally 3 to 10 carbon atoms, eg. B. β-propiolactone, γ-butyrolactone, δ-valerolactone and ε-caprolactone.

Lactams suitable according to the invention are, for example, substituted or unsubstituted lactams having a ring size of 4, 5, 6 or 7 atoms and having generally 3 to 10 carbon atoms, for example β-propiolactam, γ-butyrolactam, δ-valerolactam and ε-caprolactam.

Specifically, the at least one monomer is selected from acrylic acid, n-butyl acrylate (n-butyl acrylate), benzyl acrylate (benzyl acrylate), 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, hydroxyethyl methacrylate (HEMA), 2 Hydroxypropyl methacrylate (HPMA), C 1 -C 20 -alkyl-2-cyanoacrylates such as ethyl cyanoacrylate (ECA), methacrylic acid, methyl methacrylate (methyl methacrylate, MMA), n-butyl methacrylate (n-butyl methacrylate), benzyl methacrylate (benzyl methacrylate), styrene, O

Methylstyrene, 4-vinylpyridine, vinyl chloride, methyl vinyl ether, N-isopropylacrylamide (Nl-PAM), acrylamide, methacrylamide and mixtures thereof.

In one embodiment of the invention, the droplets of the first aerosol stream additionally contain at least one non-polymerizable additive. This additive serves, for example, by changing the physical, chemical or mechanical properties of the aerosol droplets, for example solution properties of monomers and polymers, surface tension, vapor pressure, stability of the droplets or viscosity, the properties of the particles, eg. B. to modify the particle structure, in particular the shell morphology, or the chemical properties of the shell targeted.

In principle, all additives can be used which are not polymerizable under the conditions of a photopolymerization and do not inhibit the polymerization of the monomers. It is essential for the optional additives that they are not the Entire radiation, which is provided when irradiating the mixed aerosol stream with electromagnetic radiation, preferably UV radiation, absorb. The additives mentioned are preferably present in particulate or dissolved form. Suitable additives are generally known to the person skilled in the art, and the person skilled in the art will select the additives based on the desired property profile of the polymer shell. The additive may be liquid or solid.

Examples of additives are inorganic or organic effect substances, inorganic or organic active substances, for example pharmaceutical, biological, insecticides, pesticides, solvents, oils, polymers and the like.

The at least one additive is used according to the invention generally in an amount of 0.1 to 40 wt .-%, preferably 0.2 to 30 wt .-%, particularly preferably 0.5 to 25 wt .-%, each based on the amount of the at least one monomer used. In the case of solvents, the amount of additive may also be greater.

When the above-mentioned solid additives are added, hybrid finely divided particles having a core-shell structure containing at least one polymer and / or copolymer and at least one additive are obtained.

In a preferred embodiment, the optional additional additives are metals or metal and / or semi-metal oxides, for example selected from ZnO, ΤΊΟ2, Fe-oxides, such as FeO, Fe2Ü3 and FE30 _4, boric acid and borates, alumina, silicates, aluminosilicates, S1O2, and mixtures from that. Such additives are present in the form of a solid in particulate form in the monomers. In a particularly preferred embodiment, the at least one additive, in particular the metal and / or semimetal oxide, is present in nanoparticulate form, ie with a diameter of 1 to 250 nm, preferably 5 to 100 nm, in particular 10 to 50 nm. The nanoparticles may be of any shape, e.g. B. spherical, cube-shaped, rod-shaped.

In one embodiment of the invention, at least one solvent is added to the first aerosol stream. Preferred solvents are those in which the at least one monomer is soluble but the polymer formed is insoluble. Examples of preferred solvents according to the invention are polar organic solvents such as alcohols, ketones, esters of carboxylic acids or mixtures thereof or polar aprotic organic solvents such as acetonitrile. Further possible solvents are aliphatic and cycloaliphatic hydrocarbons, such as hexane, cyclohexane, methylcyclohexane, cyclic ethers, such as tetrahydrofuran, dioxane and ionic hydrocarbons. see fluids. It is also possible to use mixtures of the solvents mentioned.

Suitable alcohols are, for example, methanol, ethanol, propanols, such as n-propanol, isopropanol, butanols, such as n-butanol, isobutanol, tert-butanol, pentanols, glycerol, glycol and mixtures thereof. Suitable ketones are, for example, acetone, methyl ethyl ketone and mixtures thereof. Suitable esters of carboxylic acids are, for example, ethyl acetate, methyl acetate, butyl acetate and acetic acid propyl ester and mixtures thereof. Particular preference is given to using ethanol or 1-propanol (n-propanol) as solvent.

If a solvent or solvent mixture is used, the amount of solvent is generally from 10 to 80% by volume, preferably from 30 to 70% by volume, particularly preferably from 40 to 60% by volume, based in each case on the amount of at least a monomer.

Suitable additives are also polymers and oils, for example polyethylene glycol, ethylene oxide / propylene oxide copolymers (EO / PO copolymers), silicone oils and mixtures thereof.

In step iv of the process according to the invention, the monomers contained in the first aerosol stream are subjected to a polymerization, wherein the polymerization is triggered by the action of electromagnetic radiation. Depending on the wavelength of the electromagnetic radiation used, the additives optionally used and the material contained in the second aerosol stream, at least one photoinitiator will be added to the monomers to initiate the polymers.

If one uses at least one photoinitiator in the process according to the invention, they will typically add this to the monomer droplets of the first aerosol stream. Suitable for this purpose are in principle all photoinitiators known to the person skilled in the art, which upon irradiation with electromagnetic radiation bring about a free-radical or ionic, ie cationic or anionic, polymerization reaction of the at least one monomer used. Since the monomer mixture for the polymerization is irradiated with electromagnetic radiation, it is preferred according to the invention to use photoinitiators which release a sufficiently large amount of (primary) radicals or cations or anions by irradiation with electromagnetic radiation. In the context of the present invention, electromagnetic radiation is understood to be that type of electromagnetic radiation which is suitable, if appropriate using a photoinitiator, to initiate a polymerization of the at least one monomer in the temperature range of the process according to the invention. For example, in the case of electromagnetic radiation to act by X-rays or gamma rays. The electromagnetic radiation used according to the invention is preferably UV radiation or visible light, ie electromagnetic radiation having a wavelength of 150 to 800 nm, preferably 180 to 500 nm, particularly preferably 200 to 400 nm, in particular 250 to 350 nm Particularly preferred is UV radiation, ie light having a wavelength of at most 400 nm, z. B. light with wavelengths in the range of 200 to 400 nm, in particular 250 to 350 nm used.

In one embodiment of the invention, the droplets of the first aerosol stream consist essentially exclusively of the at least one monomer and at least one photoinitiator, i. h., The concentration of the at least one monomer and the at least one photoinitiator is 80 to 100 wt .-%, preferably 90 to 100 wt .-%, in particular 95 to 100 wt .-%, based on the total mass of the droplets.

Examples of preferred photoinitiators for free-radical polymerization are 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropane-1-one (obtainable, for example, under the trade name Irgacure® 907 from BASF SE), 2,2 '. Azobisisobutyronitrile (AIBN) and other non-symmetrical azo derivatives, benzoin, benzoin alkyl ethers, benzoin derivatives, acetophenones, benzil ketals, α-hydroxyalkylphenones,

Aminoalkylphenones, O-acyl-a-oximinoketones, (bi) acylphosphine oxides, thioxanthone (derivatives) and mixtures thereof.

Examples of preferred photoinitiators for cationic photopolymerization are selected from substituted diaryliodonium salts, substituted triarylphosphonium salts and mixtures thereof.

Examples of preferred photoinitiators for anionic photopolymerization are selected from transition metal complexes, N-alkoxypyridinium salts, N-phenylacylpyridinium salts and mixtures thereof.

It is also possible to carry out a so-called living anionic polymerization in the pure polymer mixture, optionally comprising a secondary functionalization by means of a terminating reagent, for example by injecting a gaseous or vaporizable chemical compound in the aerosol space, preferably in the unlit indwelling zone.

In the embodiment in which at least one photoinitiator is used, the amount of photoinitiator in the droplets of the first aerosol stream is, for example, 0.1 to 10% by weight, preferably 0.5 to 8% by weight, particularly preferably 0.8 to 5 wt .-%, each based on the amount of at least one monomer present.

In a preferred embodiment of the invention, no photoinitiator is added to the first aerosol stream, i. h., the concentration of photoinitiator in the first aerosol stream is less than 0.01 wt .-%, based on the total mass of the droplets. This embodiment is suitable, for example, if the solid particles of the second aerosol stream, for example ZnO and / or T1O2, can initiate the initiation of the photopolymerization in step iv. Alternatively, in this embodiment, the photopolymerization by high-energy radiation, for. B. X-rays or gamma radiation trigger.

In the context of the invention, any solid particles can generally be used in the second aerosol stream. These may be solid organic, organometallic and inorganic compounds or metals, semimetals and nonmetals. The solid particles are preferably selected from oxides, sulfides, carbides, nitrides, carbonates, phosphates and halides of metals or semimetals, metal carbonyls, elemental metals, elemental semimetals and metal alloys. Examples are elemental metals such as Cu, Ag, Au, Pd, Pt and Halbmetalloder or metal oxides, sulfides, nitrides and carbides such as S1O2, SiC, BN, silicates, Alumosilika- te, ZnO, ZnS, T1O2, Al2O3, metal halides such as NaCl, tungsten oxides like W0 ₂ , W0 ₃

The particles used in the second aerosol stream are naturally finely divided particles which preferably have an average particle diameter (number average) in the range from 20 nm to 30 μm, often in the range from 25 nm to 10 μm, in particular in the range from 30 nm to 1 μm and especially in the Range of 40 to 500 nm. The particle size distribution is preferably monomodal, d. H. the distribution curve has only one maximum. The width of the distribution is preferably low. In particular, finely divided particles having a narrow distribution width are used, in particular those in which the distribution width Q has values in the range from 1, 0 to 1, 2:

Q = (D ₉₀ - D 10) / D ₅₀ D ₅ o: mean particle diameter

D90: particle diameter less than 90% of the particles;

D10: particle diameter less than 10% of the particles.

The particle diameters given here and below relate to the particle masses determined by means of a differential mobility analyzer and the particle diameters calculated therefrom, assuming spherical particles. The provision of the first and the second aerosol stream can generally be carried out by any method known to the person skilled in the art, or using the apparatuses generally known to the person skilled in the art and suitable carrier gases. Particularly preferably, the aerosol streams are provided in a nebuliser or atomizer with the aid of a single-fluid or multi-fluid nozzle or with an electrospray or with an ultrasonic nebulizer. If the generation of the aerosol streams is effected using nozzles, the nozzle pre-pressure upstream of the nozzles for generating the first and the second aerosol stream is generally 1 to 10 bar, in particular 1 to 3 bar. By a suitable choice of the atomizer and its operating conditions, or by classification, for. B. by means of a differential mobility analyzer (DMA), it is also possible to set particularly narrow droplet or particle size distributions. The carrier gas stream used to produce the first and second aerosol streams may be an inert gas stream selected, for example, from nitrogen (N 2), carbon dioxide (CO 2), argon (Ar), helium (He) and mixtures thereof, or air or mixtures with Air such. B. be lean air. If the polymerization is initiated and carried out by free-radical addition by addition of a photoinitiator, an inert gas stream is preferably used. If the polymerization is initiated and carried out cationically, an air or inert gas stream is preferably used. The carrier gas stream is preferably an inert gas stream. In particular, N2 (nitrogen) is used to form the carrier gas stream. This nitrogen can originate from all sources known to the person skilled in the art, for example from commercially available storage bottles, from the distillation of air, etc. The other inert gases mentioned can likewise originate from sources known to the person skilled in the art. The air used is preferably ambient or compressed air. The pressure in the carrier gas stream is according to the invention preferably at atmospheric pressure or slightly elevated atmospheric pressure. In the context of the present invention, "slightly elevated atmospheric pressure" means a pressure which is, for example, 1 to 500 mbar above atmospheric pressure. This preferably slightly elevated pressure serves in particular for the carrier gas flow to control the resistance of downstream device components, eg a filter or a filter Separation liquid, overcomes.

The first aerosol stream has droplets in a carrier gas stream containing the at least one monomer. The inventive method is generally carried out so that the droplet density in the carrier gas stream in the range of 10 ⁴ to 10 ¹⁰ droplets per cm ³ , preferably in the range of 10 ⁶ to 10 ⁸ droplets per cm ³ , most preferably in the range of 10 ⁷ bis 10 ⁸ droplets per cm ³ , lies. For example, the droplet density can be determined using a Scanning Mobility Particle Sizer (SMPS) or a condensation particle counter.

The amount of at least one monomer and optionally at least one photoinitiator and optionally at least one non-polymerizable additive, which is introduced into the carrier gas stream, according to the invention is such that a corresponding number of particles per volume is obtained. The amount of at least one monomer can be used to calculate the size of the liquid droplets formed in the aerosol and thus the size of the finely divided particles obtained after the polymerization.

The number average droplet diameter is generally selected to be in the range of 20 nm to 30 μm, often in the range of 25 to 5000 nm, in particular in the range of 30 nm to 1000 nm and especially in the range of 30 to 500 nm. The setting of the droplet diameter is typically carried out by the choice of operating conditions of the atomizer, for example by the form upstream of the atomizer, ratio mass flow of gas and liquid, etc. In Elektrospray- method, for example, the voltage can be varied in a Ultraschallver- nebler the energy input. In addition, a specific size fraction can be selected by a DMA.

To provide the second aerosol stream, typically a suspension of the solid particles with the aid of a gas will be converted into an aerosol stream. The

Suspension used to provide the second aerosol stream generally has a solids content of from 0.01 to 10 mg / mL, preferably from 0.1 to 3 mg / mL. As the liquid suspending medium, a variety of liquids may be used, preferably liquids which at normal pressure have a boiling point in the Range of 30 to 120 ° C and in particular in the range of 40 to 100 ° C. Preferred liquids are polar solvents such as water, alkanols such as methanol, ethanol, n-propanol, isopropanol or even hydrocarbons. It is also possible to use mixtures of different solvents. In particular, water is used.

The generated aerosol of the second aerosol stream, when loaded with water as the solvent, is passed, after its production, through a suitable dryer, for example a diffusion dryer, to remove the solvent, generally water.

In one embodiment, for spraying the solid particles, other mechanical devices such. B. a brush dispenser can be used. It is also possible to generate the solid particles of the second aerosol stream from the liquid droplets of an upstream aerosol stream. In general, this will be a solution of the material that will later form the solid particles of the second aerosol stream, z. For example, sodium chloride, in a solvent, for. As water, produce. This mixture is atomized, for example in a two-fluid nozzle with the aid of a carrier gas stream such as nitrogen at a nozzle pressure of 1 bar. The resulting aerosol is passed through a dryer, such as a diffusion dryer, to remove the solvent, e.g. As water, to remove largely or completely. In this way one obtains from the liquid droplets of the upstream aerosol stream an aerosol stream of solid particles, eg. B. nanoscale sodium chloride particles. This aerosol stream of solid particles is preferably used as the second aerosol stream in the process according to the invention without intermediate isolation.

The second aerosol stream provided according to the invention contains solid particles in a carrier gas stream. The inventive method is generally carried out so that the particle density in the carrier gas stream in the range of 10 ⁴ to 10 ¹⁰ particles per cm ³ , preferably in the range of 10 ⁴ to 10 ⁸ particles per cm ³ , most preferably in the range of 10 ⁴ bis 10 ⁶ particles per cm ³ . The particle density can be determined, for example, using a Scanning Mobility Particle Sizer (SMPS) or a condensation particle counter.

According to the invention, the droplets of the first aerosol stream and the particles of the second aerosol stream are charged oppositely before mixing. The droplets of the first aerosol stream can be charged both negatively and positively. The solid particles of the second aerosol stream are respectively charged in opposite directions. load. In a specific embodiment of the invention, the droplets of the first aerosol stream are negatively charged and the particles of the second aerosol stream are positively charged. To provide the first aerosol stream with charged droplets containing at least one monomer, an aerosol stream of substantially uncharged droplets containing at least one monomer is typically first generated and directs this aerosol stream to charge the droplets through an electric supercharger, e.g. B. a corona charger.

Accordingly, the provision of the second aerosol stream typically occurs by first generating an aerosol stream of substantially uncharged particles and directing this aerosol stream to charge the droplets through an electric supercharger, e.g. B. a corona charger. Corona boosters are based on the principle of gas discharge by applying a high voltage. At a sufficiently high voltage, a gas discharge and the formation of a strong electric field occur. Depending on the size of the particles used, either field charging or diffusion charging may take place. For particles larger than 1 μm in diameter, the mechanism of field loading is dominant. The ions produced as a result of the gas discharge move along the field lines. When these field lines end on the particle surface, ions strike and a particle charge results. In the case of smaller particle diameters (<1 μηη), the ions collide with the particles due to stochastic movements (diffusion charging). This process also takes place after leaving the supercharger. By selecting the process conditions and settings in the supercharger, the particles or droplets can be charged unipolar in a targeted manner and the charge density in the aerosol stream adjusted.

The aerosol of the first aerosol stream is charged using the supercharger unipolar, preferably negative.

The aerosol of the second aerosol stream is likewise charged unipolar, namely opposite to the first aerosol stream, ie preferably positively, using a supercharger. As a supercharger for the second aerosol stream in addition to the aforementioned corona supercharger also UV supercharger or supercharger with radioactive sources (bipolar supercharger) can be used. UV chargers provide another way to generate a unipolar charged aerosol. When the energetic photons hit an aerosol particle, electrons are emitted and positively charged particles remain. This photo effect depends on the material to be charged and the wavelength of the radiation. The unipolar charging of the particles of the two The aerosol flow is also possible using a radioactive source such as Kr85. Radioactive decay produces ionizing radiation that generates both negative and positive ions. This ion mixture generates a Boltzmann charge distribution distributed by 0 charges. As the diameter of the aerosol particles increases, the likelihood of multiple charge increases. For the unipolar charging of the aerosol of the second aerosol stream, corona chargers are preferred.

Chargers are preferably constructed such that a spray electrode is located in their interior, to which high voltage is applied. The voltage at the spray electrode of the supercharger for the first aerosol flow is preferably 2 to 6 kV, in particular 2 to 4 kV. The voltage at the spray electrode of the supercharger for the second aerosol stream is preferably 2 to 6 kV, in particular 3 to 5 kV.

The ratio of the first aerosol flow to the second aerosol flow is generally chosen so that the ratio of the volume flow of the first aerosol flow to the flow rate of the second aerosol flow is in the range from 8: 1 to 1: 8, in particular in the range from 3: 1 to 1: 3 is located.

In the method according to the invention, the first aerosol stream containing droplets of at least one monomer, optionally containing at least one photoinitiator, optionally containing at least one additive, is mixed with the second aerosol stream containing solid particles to obtain a mixed aerosol stream. Mixing may be accomplished by per se measures known in the art of mixing gases or aerosol streams, for example, by passing the two aerosol streams into a mixing zone or combining the two aerosol streams in a suitable manner. The mixing zone can be configured, for example, as a mixing chamber. In this case, one will direct the two aerosol streams into the mixing chamber and remove the mixed aerosol stream from the mixing chamber. The mixing zone may also be referred to as a tubular zone, i. H. as a mixing section, be configured. In this case, the two aerosol streams will be suitably combined in the tubular zone, e.g. B. by feeding them together in a tubular configured zone, for example via a Y or T-piece. The mixing within the mixing zone or mixing section can by known to those skilled internals such. B. static mixer can be accelerated.

The mixing zone or mixing section is extended in a preferred embodiment in the form of an unlit dwell zone. This residence zone promotes the accumulation of the differently charged particles into finely divided core-shell particles, which, in addition to a solid core, also have a liquid shell which blocks the monolayers. contains mers. Subsequently, the polymerization of the monomers is then initiated in the polymerization zone, wherein the shell of the finely divided core-shell particles solidifies. The average residence time of the mixed aerosol stream in the unlit residence zone is preferably in the range from 1 to 500 seconds, in particular in the range from 10 to 100 seconds.

The resulting mixed aerosol stream is then irradiated with electromagnetic radiation, e.g. B. irradiated with light, preferably UV radiation, or with high-energy radiation, so that the present monomers polymerize. Irradiation naturally takes place in a reaction zone, also referred to below as photoreactor, which lies downstream of the mixing zone.

In a further preferred embodiment of the invention, the mixed aerosol stream for photopolymerization is passed through a flow-through photoreactor. The average residence time of the mixed aerosol flow in the flow-through photoreactor is in the range from 1 to 300 seconds, in particular in the range from 5 to 60 seconds.

The irradiation of the carrier gas stream with electromagnetic radiation according to the invention can generally be carried out in any device known to the person skilled in the art. UV radiation is preferably used according to the invention. This can be produced by all devices known to the person skilled in the art, for example LEDs, excimer radiators, for example with xenon chloride (XeCl, 308 nm), xenon fluoride (XeF, 351 nm), krypton fluoride (KrF, 249 nm), krypton chloride (KrCl, 222 nm), Argon fluoride (ArF, 193 nm) or Xe2 (172 nm) as a radiation-active medium, for example, 10 mW / cm ² on the radiator surface, or with a UV fluorescent tube, for example, 8 mW / cm ² on the radiator surface. The use of an excimer radiator is advantageous since it can be dimmed by the pulsed operation, for example to 10 to 100%. As a result, an optimization of the polymerization process is relatively easy.

In a preferred embodiment of the method according to the invention, the inner wall of the photoreactor is purged with air, lean air or an inert gas, for example with N 2, Ar, He, CO 2 or mixtures thereof. This serves, for example, to suppress wall losses through polymer film formation.

In a further embodiment of the process according to the invention, it is additionally possible to inject a reactive gas for the secondary functionalization of the finely divided particles formed. The process according to the invention, in particular steps i to iv, are generally carried out at a temperature in the range from 0 to 100 ° C., in particular in the range from 10 to 50 ° C., especially in the range from 20 to 30 ° C. Thus, after leaving the photoreactors preferably used according to the invention, the polymerization within the finely divided particles is substantially complete, so that corresponding finely divided particles are obtained with core-shell structure having a solid surface and thus in the further process steps, for example separation of the formed finely divided particles, no longer changing. The finely divided particles obtained according to the invention have a core-shell structure, ie, the core of the finely divided core-shell particles consists of the solid particles of the second aerosol stream and the shell consists of the polymerized monomers and optionally the at least one non-particulate polymerizable additive of the first aerosol stream. The finely divided particles obtained according to the invention are distinguished by a particularly uniform core-shell structure. Another advantage is that the size of the droplets and the size of the solid particles largely predefines the size of the core-shell particles produced. With the setting of the droplet size over the atomizer, the resulting particle size and the shell thickness can be adjusted directly.

In a further process step, the finely divided particles formed can be separated from the carrier gas. The separation can be carried out in principle according to all methods known in the art. In a preferred embodiment, the separation of the finely divided particles formed takes place by deposition on a filter, in a further preferred embodiment by introduction into a liquid medium. The deposition in a liquid can be done for example with a wash bottle or a wet electrostatic precipitator.

The liquid medium optionally used for the separation can be selected from water, ethanol, organic solvents, for example nonpolar solvents of all kinds, for example alkanes, cycloalkanes and mixtures thereof. After introducing the finely divided particles produced into the liquid medium, a suspension of the finely divided particles in the liquid medium is obtained. This suspension can be further processed to obtain the particles, for example by separating the finely divided particles from the suspension, or this suspension is the desired process product according to the invention and can be introduced directly into the appropriate application. For long-term preservation of the resulting particle sizes, in order to avoid the agglomeration of the resulting core Shell particles further additives are added, which stabilize the particles against agglomeration.

The separation of the finely divided particles can also be carried out with a filter. Suitable filters are known per se to those skilled in the art, for example polyamide, polycarbonate filters, PTFE filters, for example with pore sizes of 50 nm, electrostatic filters.

By the method according to the invention, finely divided particles having a core-shell structure are accessible, the shell of which comprises at least one polymer and / or copolymer which is formed from the monomers of the first aerosol stream. According to the invention, the term "finely divided particles" is to be understood as particles which have a number-average particle diameter in the range from 25 nm to 30 μm, frequently in the range from 25 nm to 10 μm, in particular in the range from 30 nm to 1 μm, and especially in the range from 40 to 500 nm.

The process according to the invention naturally provides compositions containing a plurality of these finely divided particles. The mean particle size and the particle size distribution of the finely divided particles in these compositions are naturally determined by the particle size distribution of the particles of the second aerosol stream. The particle size distribution is preferably monomodal, d. H. the distribution curve has only one maximum. The width of the distribution is preferably low. Thus, distribution widths Q with values in the range of 1.0 to 1.2 can be realized with the method according to the invention.

The finely divided particles obtainable according to the invention are novel and likewise the subject of the invention.

The invention also relates to compositions of finely divided particles, for. As dispersions of finely divided particles and powder of finely divided particles, wherein the finely divided particles are selected from the finely divided particles according to the invention.

The core of the finely divided particles having a core-shell structure is generally formed by a solid organic, inorganic or organometallic material. The core of the core-shell particles generally represents on average from 1 to 99.9% by volume, in particular from 10 to 95% by volume, especially from 50 to 90% by volume, based on the total volume of the particles. The average molecular weight of the uncrosslinked polymer shell of core-shell particles can be determined by GPC. The number average molecular weight of the polymer shells is generally from 1000 to 1,000,000 g / mol, frequently from 5,000 to 100,000 g / mol, in particular from 10,000 to 80,000 g / mol, especially from 10,000 to 60,000 g / mol

The process according to the invention can be designed as a batch process or continuously. The process according to the invention is preferably carried out continuously.

Brief Description:

FIGS. 1 and 2 show TEM images of a finely divided particle having a core-shell structure obtained in Example 1.

FIG. 3 shows a TEM image of a finely divided particle having a core-shell structure obtained in Example 2.

FIG. 4 shows a TEM image of a finely divided particle having a core-shell structure obtained in Example 3. FIG. 5 shows a TEM image of a finely divided particle having a core-shell structure obtained in Example 4.

FIG. 6 shows a TEM image of finely divided particles having a core-shell structure obtained in Example 5.

Examples:

Analytical Methods: Transmission electron microscopy (TEM) visualizes the nuclei and shells of the core-shell particles. Fourier transform infrared spectroscopy (FTIR) serves as a spectroscopic method to show that the double bonds of the monomer molecules in the polymer structures are absent or that the liquid monomer layer has become solid polymer. With gel permeation chromatography (GPC), the average molecular weight of the polymer shell can be determined.

General experiment: To generate the first aerosol stream, the solution of at least one monomer, optionally at least one photoinitiator, optionally at least one additive and optionally at least one crosslinker with the aid of the carrier gas stream in the atomizer (atomizer with two-fluid nozzle, Topaz model ATM 220) is fed. After leaving the nebulizer, the aerosol is electrically charged in a Corona charger.

To generate the second aerosol stream, the suspension of the solid particles is fed into the atomizer, for example in water, with the aid of the carrier gas stream (atomizer with two-component nozzle, Topas, model ATM 220). The aerosol then flows through a diffusion dryer (Topas, model DDU 570 / H) in order to minimize the water content of the aerosol. After leaving the nebulizer, the aerosol is electrically charged in a corona charger opposite to the first aerosol stream.

To generate the second aerosol stream of solid sodium chloride particles in Examples 4 and 5, the second aerosol stream is provided according to the following procedure: A solution of sodium chloride in water having a solids content of 3.5 mg of sodium chloride per 1 ml of water is prepared. This mixture is atomized by means of the carrier gas stream at a nozzle pressure of 1 bar in a two-fluid nozzle. The generated aerosol, which consists of sodium chloride-containing water droplets, is passed through a diffusion dryer. After leaving the diffusion dryer, the second aerosol stream of solid, nanoscale sodium chloride particles is obtained, which is charged electrically in a corona charger opposite to the first aerosol stream.

The first and second aerosol streams are combined and flow through a darkened dwell zone. The mixed aerosol stream then flows through one of the two self-constructed photoreactors, photoreactor 1 or 2 (photoreactor 1 has a UV excimer emitter with a photon output of 10 mW / cm ² on the radiator surface as UV source.) In this photoreactor, the UV Photoreactor 2 consists of 3 identical UV radiators, each equipped with a UV fluorescence tube and a photon output of 8 mW / cm ² on the radiator surface. Radiator outside the reaction volume, so that the irradiation takes place inwards).

In all examples, nitrogen (N2) was used as the carrier gas. List of chemicals used

methyl methacrylate

n-butyl acrylate

- 1, 6-hexanediol diacrylate

Photoinitiator: Irgacure® 907 (BASF SE) (2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one)

Spherical nanoscale silica, particle diameter 250 nm (manufacturer: Microparticles)

- approximately spherical, nanoscale gold, particle diameter 100 nm (manufacturer: Postnova)

Nanoscale zinc oxide: 40% by weight of zinc oxide nanoparticles in ethanol, particle diameter 30 nm (manufacturer: Sigma Aldrich)

sodium chloride

Example 1 :

First aerosol stream: monomer: methyl methacrylate

Photoinitiator: Irgacure® 907, 1% by weight in methyl methacrylate

Crosslinker: 1, 6-hexanediol diacrylate, 10 vol .-%, based on the amount of methyl methacrylate nozzle pressure: 1 bar

Charging voltage: 2 kV

Polarity of the droplets: negative

Concentration of the monomer droplets in the aerosol: 10 ⁷ to 10 ⁸ droplets / cm ³

Average droplet diameter: 131, 4 nm, standard deviation 0.57 μηη

Elementary charges per droplet: 10 to 60, depending on the diameter

Second aerosol stream: Solid: spherical nanoscale silica

Concentration: 1 mg S1O2 per 1 ml_ H2O

Nozzle pressure: 2 bar

Charging voltage: 4 kV Polarity of the particles: positive

Concentration of the particles in the aerosol: 10 ⁵ particles / cm ³

Average particle diameter: 250 nm, standard deviation 0.1 μm Elementary charges per particle: 40

Mixed aerosol stream:

Residence time in unlit indwelling zone: 10 sec

Irradiation time: 3 min

Photoreactor: photoreactor 1

Example 2: First Aerosol Stream:

Monomer: methyl methacrylate

Photoinitiator: Irgacure® 907, 1% by weight, in methyl methacrylate

Crosslinker: 1, 6-hexanediol diacrylate, 10 vol .-%, based on the amount

methacrylate

Nozzle pressure: 1 bar

Charging voltage: 2 kV

Polarity of the droplets: negative

Average droplet diameter: 131, 4 nm, standard deviation 0.57 μηη

Elementary charges per droplet: 10 to 60, depending on the diameter of the second aerosol stream:

Solid: approximately spherical, nanoscale gold

Concentration: 0.6 mg Au per 1 ml_ H2O

Nozzle pressure: 2 bar

Charging voltage: 4 kV

Polarity of the particles: positive

Concentration of the particles in the aerosol: 10 ⁵ particles / cm ³ Average particle diameter: 100 nm

Elementary charges per particle: 20

Mixed aerosol stream:

Residence time in unlit indwelling zone: 10 sec

Irradiation time: 3 min

Photoreactor: photoreactor 2 Example 3:

First aerosol stream:

Monomer: methyl methacrylate

Photoinitiator: Irgacure® 907, 1% by weight, in methyl methacrylate

Crosslinker: 1, 6-hexanediol diacrylate, 10 vol .-%, based on the amount of methyl methacrylate

Ethanol: Add 0.2 mL of the suspension of zinc oxide nanoparticles in ethanol per 15 mL of methyl methacrylate, this suspension is added to the monomer solution.

Nozzle pressure: 1 bar

Charging voltage: 2 kV

Polarity of the droplets: negative

Average droplet diameter: 131, 4 nm, standard deviation 0.57 μηη

Solid: spherical, nanoscale silica

Concentration: 1 mg S1O2 per 1 mL H2O

Nozzle pressure: 2 bar

Charging voltage: 4 kV

Polarity of the particles: positive

Concentration of the particles in the aerosol: 10 ⁵ particles / cm ³ Average particle diameter: 250 nm, standard deviation 0.1 μm Elementary charges per particle: 40

Mixed aerosol stream:

Residence time in unlit indwelling zone: 10 sec

Irradiation time: 3 min

Photoreactor: Photoreactor 2 Example 4:

First aerosol stream:

Monomer: methyl methacrylate

Photoinitiator: Irgacure® 907, 1% by weight in methyl methacrylate

Nozzle pressure 1 bar

Charging voltage: 3.5 kV

Polarity of the droplets: negative

Concentration of the monomer droplets in the aerosol: approx. 10 ⁷ droplets / cm ³

Average droplet diameter: approx. 130 nm

Elemental charges per droplet: about 10 to 60, depending on the diameter

Second aerosol stream:

Solid: nanosodium sodium chloride

Nozzle pressure: 2 bar

Charging voltage: 4 kV

Polarity of the particles: positive

Concentration of the particles in the aerosol: approx. 10 ⁷ particles / cm ³

Average particle diameter: about 65 nm

Elementary charges per particle: approx. 10 to 60, depending on the diameter

Mixed aerosol stream: Residence time in unlit indwelling zone: 60 sec

Irradiation time: 3 min

Photoreactor: photoreactor 2

Example 5:

First aerosol stream: Monomer: 1,6-hexanediol diacrylate

Photoinitiator: Irgacure® 907, 1% by weight in 1,6-hexanediol diacrylate crosslinker:

Nozzle pressure: 1 bar

Charging voltage: 3.5 kV

Polarity of the droplets: negative

Concentration of the monomer droplets in the aerosol: about 10 ⁷ droplets / cm ³ Mean droplet diameter: about 130 nm

Elemental charges per droplet: about 10 to 60, depending on the diameter

Second aerosol stream:

Solid: nanosodium sodium chloride

Nozzle pressure: 2 bar

Charging voltage: 4 kV

Polarity of the particles: positive Concentration of the particles in the aerosol: approx. 10 ⁷ particles / cm ³

Average particle diameter: about 65 nm

Elementary charges per particle: approx. 10 to 60, depending on diameter Mixed aerosol flow:

Residence time in unlit indwelling zone: 60 sec

Irradiation time: 3 min

Photoreactor: photoreactor 2 Example 6:

Finely divided particles having a core-shell structure were prepared in analogy to the process carried out in Example 1. As a monomer in the first aerosol stream n-butyl acrylate was used. It was used photoinitiator, but no crosslinker. The solid in the second aerosol stream was spherical nanoscale silica.

There were obtained finely divided particles with spheres of spherical, nanoscale silica, the shells of poly-n-butyl acrylate had.

Since no crosslinker was added, the shells of the finely divided particles with core-shell structure were not visible in TEM images.

Claims

claims:

Process for the production of finely divided particles having a core-shell structure, the shell of which comprises at least one polymer, the process comprising the following steps:

ii. Providing a second aerosol stream of solid particles in a carrier gas stream and charging the solid particles of the aerosol with an electrical charge opposite the electrical charge of the droplets of the first aerosol stream;

The method of claim 1, wherein the droplets of the first aerosol stream consist essentially of the at least one monomer and at least one photoinitiator.

3. The method of claim 1, wherein the droplets of the first aerosol stream additionally contain at least one non-polymerizable additive. 4. The method according to any one of the preceding claims, wherein the droplets of the first aerosol stream have a number average droplet diameter in the range of 20 nm to 30 μηη, in particular in the range of 30 nm to 1000 nm.

Method according to one of the preceding claims, wherein the first aerosol stream has a droplet density in the range of 10 ⁴ to 10 ¹⁰ , in particular in the range of 10 ⁶ to 10 ⁸ , droplets per cm ³ .

Method according to one of the preceding claims, wherein the at least

a monomer is selected from olefinically unsaturated monomers and cyclic ethers, lactones and lactams. Method according to one of the preceding claims, wherein the at least one monomer is selected from monoolefinically unsaturated monomers and mixtures of at least one monoolefinically unsaturated monomer with at least one poly olefinically unsaturated monomer.

A process according to claim 6 or 7, wherein the at least one monomer comprises at least one monoolefinically unsaturated monomer selected from monoolefinically unsaturated C3-C6 monocarboxylic acids, monoolefinically unsaturated C4-C6 dicarboxylic acids, esters of monoolefinically unsaturated C3-C6 monocarboxylic acids, esters monoolefinically unsaturated C 4 -C 6 -dicarboxylic acids, amides of monoolefinically unsaturated C 3 -C 6 -monocarboxylic acids, N-vinylamides, N-vinyllactams, vinylaromatics, vinyl ethers, vinyl, allyl and methallyl esters, monoolefinically unsaturated nitriles, α-olefins, monoolefinically unsaturated sulfonic acids, monoolefinically unsaturated phosphonic acids and monoolefinically unsaturated Phosphorsäurehalbestern.

A method according to any one of the preceding claims, wherein first generating an aerosol stream of substantially uncharged droplets containing at least one monomer and directing this aerosol stream to charge the droplets through an electric supercharger.

Method according to one of the preceding claims, wherein the particles of the second aerosol stream have a number-average particle diameter in the range of 20 nm to 30 μηη, in particular in the range of 30 nm to 1000 nm.

1 1. Method according to one of the preceding claims, wherein the second aerosol stream has a particle density of 10 ⁴ to 10 ¹⁰ particles per cm ³ , in particular in the range of 10 ⁴ to 10 ⁶ particles per cm ³ .

12. The method according to any one of the preceding claims, wherein the particles of the second aerosol stream consist of at least one solid organic, inorganic or organometallic material. 13. The method of claim 12, wherein the particles of the second aerosol stream consist of a material which is oxides, sulfides, carbides, nitrides, carbonates, phosphates and halides of metals or semimetals, metal car- bonylene, elemental metals, elemental semi-metals and metal alloys.

14. The method according to any one of the preceding claims, wherein passing the mixed aerosol stream before the irradiation with electromagnetic radiation through an unlit dwell zone.

15. The method of claim 14, wherein the average residence time of the mixed aerosol stream in the residence zone in the range of 1 to 500 sec, in particular in the range of 10 to 100 sec.

A process according to any one of the preceding claims wherein the mixed aerosol stream is passed through a flow photoreactor for polymerization. 17. The method of claim 16, wherein the average residence time of the mixed aerosol flow in the flow-through photoreactor in the range of 1 to 300 sec, in particular in the range of 5 to 60 sec.

18. The method according to any one of the preceding claims, wherein after the photopolymerization, the finely divided particles having a core-shell structure on a

Filter or a surface deposits.

19. The method according to any one of the preceding claims, wherein depositing the finely divided particles with core-shell structure by introducing the aerosol stream into a liquid medium after photopolymerization.

20. Finely divided particles with core-shell structure, obtainable by a method according to one of the preceding claims. 21. Finely divided particles according to Claim 20, which have a number-average particle diameter in the range from 25 nm to 30 μm, in particular in the range from 30 nm to 1 μm.

22. Finely divided particles according to claim 20 or 21, wherein the core is formed by a solid organic, inorganic or organometallic material.

23. Finely divided particles according to any one of claims 20 to 22, wherein the core of the core-shell particles on average 1 to 99.9 vol .-%, in particular 10 to 95 vol .-%, specifically 50 to 90 vol .-% based on the total volume of the particles makes.