JP2015530434A - Fine particles having a core-shell structure - Google Patents

Abstract

The subject of the present invention is a process for producing finely divided particles having a core-shell structure, wherein the shell comprises at least one polymer, said process comprising i. Providing a first aerosol stream of droplets in a carrier gas stream, wherein the droplets contain at least one monomer and charge the droplets of the first aerosol; ii. Providing a second aerosol stream of solid particles in a carrier gas stream and charging the solid particles of the aerosol with a charge opposite to that of the droplets of the first aerosol stream; iii. Mixing a first aerosol stream with a second aerosol stream to obtain a mixed aerosol stream; and iv. The method includes initiating polymerization of the monomer by irradiating the mixed aerosol stream with electromagnetic radiation. The subject of the present invention is also fine particles having a core-shell structure obtained by this method.

Description

  The present invention relates to a method for producing finely divided particles having a core-shell structure, wherein the shell contains at least one polymer. The present invention further relates to the fine particles themselves having a core-shell structure which can be obtained by this method.

  The formation and structuring of fine-grained composite particles, ie particles having a multiphase morphology, in particular particles having a core-shell structure or core-shell morphology, according to the purpose, is a special application Of particular interest for producing particles with unique properties. Coated particulate particles having a core-shell structure are of interest for many applications, for example in dye compositions or as catalysts. The polymer coating prevents agglomeration of the particles, which results in higher color strength or improved catalyst performance. In medical applications, marker substances are polymer coated to suppress the harmful effects of the particles on living organisms. Furthermore, the polymer coating can be used to protect the core material from external influences such as corrosion, oxidation, reduction, water and the like. Moreover, the properties of the particles to be coated, such as the conductivity, can be changed. What is possible here is, for example, fine particles with a core-shell structure as a hybrid material for printed electronics, consisting of a semiconductor or conductor polymer with semiconductor or conductor inorganic particles. Therefore, a wide field of use is given for fine particles having a core-shell structure in optical systems, electronic systems, chemical systems, biotechnology systems and medical systems.

  From the state of the art, a number of methods for producing composite particles are known. Mentioned here are in particular methods in the liquid phase, such as stepwise emulsion polymerization, emulsion polymerization in suspensions of non-polymerizable particles or emulsions of non-polymerizable droplets, core cells. Microencapsulation by basation and the like, as well as methods in the gas phase, such as photoinduced or chemically induced vapor phase growth.

  B. Zhang et al., J. Nanopart. Res 2008, 10, 173-178 describes coating sodium chloride nanoparticles using photo-induced chemical vapor deposition; AM Boies et al., Nanotechnology 2009, 20, 29, 295604 describes the production of inorganic core-shell particles using chemical vapor deposition.

  JF Widmann et al., J. Colloid Interface Sci. 1998, 199, 197-205 describes a method in which isolated microparticles are captured in an electrokinetic trap and contacted with a monomer droplet. ing. The resulting liquid nanoparticle coating is polymerized photochemically.

  The process for producing finely divided composite particles known from the state of the art has a number of drawbacks. On the one hand, the composite particles are largely non-uniform, i.e. broad particle size distribution, non-uniform particle shape or non-uniform particle composition. Many finely divided composite particles do not have an outstanding core-shell morphology, but only an additional structure. Also, using a known method, only a specific particle size range can be achieved, and in many of the known methods, small particles can only be produced with limited or no production at all. It is.

  Known gas phase production methods for core-shell particles are often limited to specific particle-monomer combinations. Moreover, disadvantageous to the liquid phase process is the use of emulsifiers that are undesirable for many applications and often cannot be separated. Furthermore, many of the known production methods for finely divided composite particles are not suitable for large industrial use because of their low throughput.

  The object of the present invention is to provide a process for producing finely divided core-shell particles which overcomes the drawbacks of the state of the art. In particular, the method should allow high throughput, should allow the use of surfactants such as emulsifiers and surfactants, and should be applicable to a large number of core and monomer materials. It is.

  This problem is surprisingly solved by a method for producing finely divided particles having a core-shell structure, the shell comprising at least one polymer, wherein the method is described in more detail here and below. Process described i. ~ Iv. Two aerosol streams having opposite charges in the process are mixed together, wherein the first aerosol stream contains polymerizable monomers and the second aerosol stream contains solid particles Contain and subsequently photochemically cause polymerization. In this way, particles having a core-shell structure are obtained, wherein the particles of the second aerosol stream form the core and the polymerized monomers of the first aerosol stream form the polymer shell. To do.

The subject of the present invention is therefore the method described here and below comprising the following steps:
i. Providing a first aerosol stream of droplets in a carrier gas stream, wherein the droplets contain at least one monomer and charge the droplets of the first aerosol;
ii. Providing a second aerosol stream of solid particles in a carrier gas stream and charging the solid particles of the aerosol with a charge opposite to the charge of the droplets of the first aerosol stream;
iii. Mixing a first aerosol stream with a second aerosol stream to obtain a mixed aerosol stream;
iv. Initiating polymerization of the monomer by irradiating the mixed aerosol stream with electromagnetic radiation.

  The advantage of the process according to the invention is on the one hand a high product purity, since it is not necessary to add surfactants, such as emulsifiers or surfactants. Furthermore, the addition of a solvent is unnecessary. If the particles of the second aerosol stream act as a photoinitiator or high energy radiation is used, it is not necessary to add a photoinitiator to the monomer. The method according to the invention allows the simultaneous coating of a large number of particles. The method can be applied to a large number of solid core particles because charging and condensing of oppositely charged droplets and particles is a purely physical process. The finely divided core-shell particles obtainable according to the present invention exhibit a particularly uniform core-shell structure. A further advantage of the method according to the invention is that, due to the electrostatic charging of the solid particles and droplets, the condensation of the particles or droplets with each other, ie both within the aerosol stream, to the same charge. Is to be avoided. Thereby, a narrower particle size distribution and thus better reproducibility of the resulting core-shell particles can be achieved using the method according to the invention.

  A further advantage of the method according to the invention compared to the method using thermally induced polymerization is that the heating can be abandoned. Because the monomer partially evaporates due to the heating required during thermally induced polymerization, the control of the particle size and the shell thickness is complex, often not reproducible and sometimes incomplete. Only a good coating is achieved. In contrast, using the method according to the present invention, the thickness of the polymer shell can be easily adapted to the purpose by changing the droplet size in the first aerosol stream and by the ratio of the mass flow rates in the aerosol stream. Can be adjusted to.

  The structure of the finely divided core-shell particles obtained by the photopolymerization depends on its process parameters such as the droplet size of the first aerosol stream, the number of charges on the droplets or particles, the particle concentration and droplet concentration, the mixing By varying the zone geometry and length, and optionally the residence time in the unirradiated residence zone present, one skilled in the art can adjust to the desired result.

  In accordance with the present invention, the particles produced contain at least one polymer, which in the sense of the present invention is to be understood as a homopolymer and / or copolymer. The concept “homopolymer” should be understood to be polymers composed of the same monomers. The concept of “copolymer” is to be understood as a polymer composed of at least two different monomers.

  In general, all monomers that can be polymerized under the action of electromagnetic radiation in the first aerosol stream of the process according to the invention can be used. These are inter alia olefinically unsaturated monomers as well as cyclic monomers that accept photochemically induced ring-opening polymerizations.

  The monomer of the first aerosol stream can be, for example, neutral, acidic, basic or cationic.

  Preferably, the monomer is selected from among olefinically unsaturated monomers, i.e., monomers having at least one, e.g. 1, 2, 3, or 4, C = C double bonds, In doing so, among other things, the C = C double bond is a vinylic double bond, i.e. a mono-substituted double bond, or a vinylidene double bond, i.e. both substituents are of the C = C double bond. Monomers that are present in the form of disubstituted double bonds attached to the same carbon atom are preferred. Preference is given in particular to olefinic, in which the double bond is in a conjugated state with a non-polymerizable double bond, for example a carbonyl group, a nitrile group or an aromatic ring, for example a benzene ring, an imidazole ring or a pyridine ring. Unsaturated monomer.

  Preferably, the at least one monomer is from among monoolefinically unsaturated monomers and in particular from a mixture of at least one monoolefinically unsaturated monomer and at least one polyolefinic unsaturated monomer. Has been selected.

  In a preferred embodiment of the invention, the first aerosol stream used in the process according to the invention comprises at least one polyolefinic unsaturated monomer (crosslinker) in addition to at least one such monomer.

  The polyolefinic unsaturated monomer causes crosslinking in the polymerization reaction of the prepared monomer, and thus increases the molecular weight of the resulting polymer. The at least one crosslinking agent is, for example, 1 to 80% by weight, preferably 2 to 20% by weight, particularly preferably 3 to 15% by weight, based on the total amount of the olefinically unsaturated monomer, used.

  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 consists essentially of at least one polyolefinic unsaturated monomer (crosslinker). Including. In this embodiment, the at least one polyolefinic unsaturated monomer is typically 80-100% by weight, preferably 90-100% by weight, particularly preferably 97, based on the total amount of the olefinically unsaturated monomer, respectively. Used in an amount of ˜100% by weight.

  Preferably, at least 90% by weight of the monomers present in the aerosol stream are selected from among neutral olefinically unsaturated monomers.

Neutral monoolefinically unsaturated monomers which are suitable according to the invention are typically monoolefinically unsaturated C ₃ -C ₆ -monocarboxylic acids, monoolefinically unsaturated C ₄ -C ₆ -dicarboxylic acids Monoolefinically unsaturated C ₃ -C ₆ -monocarboxylic acid esters, monoolefinically unsaturated C ₄ -C ₆ -dicarboxylic acid esters, monoolefinically unsaturated C ₃ -C ₆ -monocarboxylic acid amides , N-vinyl amide, N-vinyl lactam, vinyl aromatic compound, vinyl ether, vinyl ester, allyl ester and methallyl ester, monoolefinically unsaturated nitrile, α-olefin, monoolefinically unsaturated sulfonic acid, monoolefinically unsaturated Among phosphonic acids and monoolefinically unsaturated phosphoric acid half esters, C ₃ -C ₆ - esters of monocarboxylic acids, monoolefinic unsaturated C ₄ -C ₆ - esters of dicarboxylic acids, mono-olefinically unsaturated C ₃ -C ₆ - amides of monocarboxylic acids, ethylenically unsaturated nitriles And from neutral monoethylenically unsaturated monomers from the group of vinyl ethers and with one or more acidic monomers such as monoolefinically unsaturated C ₃ -C ₆ -monocarboxylic acids, monoolefinically unsaturated monomers. saturated C ₄ -C ₆ - dicarboxylic acid, mono-olefinically unsaturated sulfonic acids, from a mixture of mono-olefinically unsaturated phosphonic acids and monoolefinically unsaturated phosphoric acid half esters, are selected.

Examples of neutral monoolefinically unsaturated monomers that are suitable according to the invention include, inter alia, the following groups M1-M12 monomers, in particular the groups M1, M2, M4, M6, M7, M8, M9, M10. And M12, in particular those of the groups M1, M2, M6, M7, M8, M9 and M10:
M1 monoolefinically unsaturated C ₃ -C ₆ - monocarboxylic acids, C ₁ -C ₂₀ - alkanols, C ₅ -C ₈ - cycloalkanols, phenyl -C ₁ -C ₄ - alkanols or phenoxy -C ₁ -C Esters with ₄ -alkanols, especially said esters of acrylic acid as well as those of methacrylic acid, such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-butyl Acrylate, isobutyl acrylate, t-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, 3-propyl heptyl acrylate, decyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, benzyl acrylate Rat 2-phenylethyl acrylate, 1-phenylethyl acrylate, 2-phenoxyethyl acrylate, and esters of methacrylic acid such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl Methacrylate, 2-butyl methacrylate, isobutyl methacrylate, t-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 monoolefinically unsaturated C ₄ -C ₆ - and dicarboxylic acids, C ₁ -C ₂₀ - alkanols, C ₅ -C ₈ - cycloalkanols, phenyl -C ₁ -C ₄ - alkanols or phenoxy -C ₁ -C ₄ Diesters with alkanols, in particular the aforementioned diesters of maleic acid and the diesters of fumaric acid, in particular di-C ₁ -C ₂₀ -alkyl maleates and di-C ₁ -C ₂₀ -alkyl fumarate, such as dimethyl maleate, Diethyl maleate, di-n-butyl maleate, dimethyl fumarate, diethyl fumarate and di-n-butyl fumarate;
M3 vinyl aromatic hydrocarbons such as styrene, vinyl toluenes, t-butyl styrene, α-methyl styrene, especially styrene;
M4 saturated aliphatic C ₂ -C ₁₈ - vinyl esters of monocarboxylic acids, allyl esters and methallyl esters, such as vinyl acetate, vinyl propionate, vinyl butyrate, Binirupibarato, vinyl hexanoate, vinyl 2-ethylhex Noate, vinyl laurate and vinyl stearate and the corresponding allyl and methallyl esters, and M5 alpha-olefins having 2 to 20 carbon atoms and cycloolefins having 5 to 10 carbon atoms, such as ethene, propene, 1 -Butene, isobutene, 1-pentene, cyclopentene, cyclohexene and cycloheptene;
M6 monoolefinically unsaturated C ₃ -C ₆ -monocarboxylic acids and polyether monools, especially C ₁ -C ₂₀ -alkyl poly-C ₂ -C ₄ -alkylene glycols, especially C ₁ -C ₂₀ -alkyl An ester with polyethylene glycol, in which case the alkylpolyalkylene glycol group usually has a molecular weight (number average) in the range from 200 to 5000 g / mol, in particular said ester of acrylic acid and said methacrylic acid Esters of;
M7 monoolefinically unsaturated nitriles such as acrylonitrile or methacrylonitrile,
M8 amides of said monoolefinically unsaturated C ₃ -C ₈ -monocarboxylic acids, in particular acrylamide and methacrylamide,
M9 N- (C ₁ -C ₂₀ -alkyl) amide and N, N-di- (C ₁ -C ₂₀ -alkyl) amide of the monoolefinically unsaturated C ₃ -C ₈ -monocarboxylic acid described above;
M10 Hydroxyalkyl esters of the above monoolefinically unsaturated C ₃ -C ₈ -monocarboxylic acids, such as hydroxyethyl acrylate, hydroxyethyl methacrylate, 2- and 3-hydroxypropyl acrylate, 2- and 3-hydroxypropyl Methacrylate;
M11 aliphatic C ₁ -C ₁₀ -carboxylic acid N-vinylamides and N-vinyllactams, such as N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone and N-vinylcaprolactam;
M12 C ₁ -C ₂₀ -alkanol vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, benzyl vinyl ether.

Examples of acidic monoolefinically unsaturated monomers that are suitable according to the invention are, inter alia, monomers of the following groups M13 to M17:
M13 monoolefinically unsaturated C ₃ -C ₆ -monocarboxylic acids such as acrylic acid, methacrylic acid, vinylpropionic acid and ethacrylic acid and monoolefinically unsaturated C ₄ -C ₆ -dicarboxylic acids such as itaconic acid, maleic acid Fumaric acid and citraconic acid and their anhydrides;
M14 Monoolefinically unsaturated sulfonic acids and their salts in which the sulfonic acid group is bound to an aliphatic hydrocarbon group, such as vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methylpropane Sulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, 2-acrylamidoethanesulfonic acid, 2-methacrylamideamidoethanesulfonic acid, 2-acryloxyethanesulfonic acid, 2-methacryloxyethanesulfonic acid, 3-acryloxy Propanesulfonic acid and 2-methacryloxypropanesulfonic acid and their salts,
M15 vinyl aromatic sulfonic acids, ie monoolefinically unsaturated sulfonic acids and their salts, eg styrene sulfonic acids, eg 2-3, in which the sulfonic acid group is bonded to an aromatic hydrocarbon group, in particular a phenyl ring -Or 4-vinylbenzenesulfonic acid and salts thereof,
M16 Monoolefinically unsaturated phosphonic acids and their salts, such as vinylphosphonic acid, 2-acrylamido-2-methylpropanephosphonic acid, 2-methacrylamide-2, wherein the phosphonic acid group is bound to an aliphatic hydrocarbon group -Methylpropanephosphonic acid, 2-acrylamidoethanephosphonic acid, 2-methacrylamideamidoethanephosphonic acid, 2-acryloxyethanephosphonic acid, 2-methacryloxyethanephosphonic acid, 3-acryloxypropanephosphonic acid and 2-methacryloxypropane Phosphonic acids and their salts,
M17 monoolefinically unsaturated phosphoric acid half esters, especially half esters of phosphoric acid with hydroxy-C ₂ -C ₄ -alkyl acrylates and hydroxy-C ₂ -C ₄ -alkyl methacrylates, such as 2-acryloxyethyl Phosphate, 2-methacryloxyethyl phosphate, 3-acryloxypropyl phosphate, 3-methacryloxypropyl phosphate, 4-acryloxybutyl phosphate and 4-methacryloxybutyl phosphate and their salts.

Examples of basic and cationic monoolefinically unsaturated monomers that 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 heterocyclic compounds such as 2-vinyl pyridine, 3-vinyl pyridine, 4-vinyl pyridine and N-vinyl imidazole;
M19 Quaternized vinyl heterocyclic compounds such as 1-methyl-2-vinylpyridinium salt, 1-methyl-2-vinylpyridinium salt, 1-methyl-4-vinylpyridinium salt, and N-methyl-N′- Vinyl imidazolium salts, such as their chlorides or methosulfates;
M20 N, N- (di-C ₁ -C ₁₀ -alkylamino) -C ₂ -C ₄ -alkylamides and N, N- (di) of the above monoolefinically unsaturated C ₃ -C ₈ -monocarboxylic acids. -C ₁ -C ₁₀ - alkylamino) -C ₂ -C ₄ - alkyl esters, for example 2- (N, N- dimethylamino) ethyl acrylamide, 2- (N, N- dimethylamino) ethyl methacrylamide, 2- (N, N-dimethylamino) propylacrylamide, 2- (N, N-dimethylamino) propylmethacrylamide, 3- (N, N-dimethylamino) propylacrylamide, 3- (N, N-dimethylamino) propylmethacrylamide Amido, 2- (N, N-diethylamino) ethylacrylamide, 2- (N, N-diethylamino) ethylmethacrylamide, 2- (N, N-di-) Tilamino) propylacrylamide, 2- (N, N-diethylamino) propylmethacrylamide, 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 DOO, 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- (tris of the above monoolefinically unsaturated C ₃ -C ₈ -monocarboxylic acids. -C ₁ -C ₁₀ - alkyl ammonium) -C ₂ -C ₄ - alkyl esters, for example 2- (N, N, N- trimethylammonium) ethyl acrylamide, 2- (N, N, N- trimethylammonium) ethyl methacrylate Amide, 2- (N, N, N-trimethylammonium) propylacrylamide, 2- (N, N, N-trimethylammonium) propylmethacrylamide, 3- (N, N, N-trimethylammonium) propylacrylamide, 3 -(N, N, N-trimethylammonium) -propylmethacrylamide, 2- (N, N, N-triethyla Momonium) ethylacrylamide, 2- (N, N, N-triethylammonium) ethylmethacrylamide, 2- (N, N, N-triethylammonium) -propylacrylamide, 2- (N, N, N-triethylammonium) propyl Methacrylamide, 3- (N, N, N-triethylammonium) propylacrylamide, 3- (N, N, N-triethylammonium) -propylmethacrylamide, 2- (N, N, N-trimethylammonium) ethyl acrylate 2- (N, N, N-trimethylammonium) ethyl methacrylate, 2- (N, N, N-trimethylammonium) propyl acrylate, 2- (N, N, N-trimethylammonium) propyl methacrylate, 3 -(N, N, N-trimethylammonium ) 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, in particular their chloride, methosulfate and ethosulfate.

  Polyolefinically unsaturated compounds (crosslinkers) are, for example, divinylbenzene, diesters and triesters of olefinically unsaturated carboxylic acids, in particular diols or bisacrylates and trisacrylates of polyols having three or more OH groups, such as ethylene. Glycol, diethylene glycol, triethylene glycol, neopentyl glycol or polyethylene glycol bisacrylate and bismethacrylate, 1,6-hexanediol diacrylate (HDDA), allyl methacrylate (AMA) and trimethylolpropane trimethacrylate ( PMPTMA).

  Saturated cyclic compounds which can be polymerized by ring opening polymerization initiated photochemically in the process according to the invention are also suitable as monomers. Examples of such monomers are cyclic ethers such as epoxides, oxetanes, furans and cyclic acetals, and lactones and lactams.

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

  Examples of cyclic ethers are also cyclic acetals, for example substituted or unsubstituted cyclic acetals having a ring size of 5 or 6 carbon atoms, generally derived from aldehydes having 1 to 10 carbon atoms. is there. These include trioxane, 1,3-dioxane and 1,3-dioxolane, among others.

  Examples of cyclic ethers are substituted or unsubstituted cyclic monoethers (oxetanes and furans) having a ring size of 4 or 5 atoms, generally having 3 to 10 carbon atoms, such as oxetanes, 3 3,3-dimethyloxetane, tetrahydrofuran, 3-methyltetrahydrofuran, 3,3-dimethyltetrahydrofuran or 3,4-dimethyltetrahydrofuran.

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

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

In particular, the at least one monomer is acrylic acid, acrylic acid-n-butyl ester (n-butyl acrylate), acrylic acid benzyl ester (benzyl acrylate), 1,6-hexanediol diacrylate, , 4-butanediol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, hydroxyethyl methacrylate (HEMA), 2-hydroxypropyl methacrylate _{(HPMA), C 1 ~C 20} - alkyl-2-cyano Acrylates such as ethyl cyanoacrylate (ECA), methacrylic acid, methacrylic acid methyl ester (methyl methacrylate, MMA), methacrylic acid-n-butyl ester (n-butyl methacrylate), methacrylic acid benzyl ester (benzyl Methacrylate), styrene, α-methylstyrene, 4-vinylpyridine, vinyl chloride, methyl vinyl ether, N-isopropylacrylamide (NIPAM), 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 can be used, for example, by altering the physical, chemical or mechanical properties of the aerosol droplets, such as solution properties of monomers and polymers, surface tension, vapor pressure, stability or viscosity of the droplets. To modify the properties of the particles, such as the particle structure, in particular the shell morphology, or the chemical properties of the shell, to suit the purpose.

  In principle, all additives can be used which are non-polymerizable under the conditions of photopolymerization and do not inhibit the polymerization of the monomers. Essential to the optionally present additives is that they do not absorb all the radiation available when irradiating the mixed aerosol stream with electromagnetic radiation, preferably ultraviolet radiation. Preferably, the additive is present in granular or dissolved form. Suitable additives are known in principle to those skilled in the art, and the person skilled in the art will select the additive based on an overview of the desired properties of the polymer shell. The additive may be liquid or solid.

  Examples of additives are inorganic or organic active substances, inorganic or organic active substances such as pharmaceutically active substances, biologically active substances, insecticidal active substances, agrochemical active substances, solvents, oils, polymers and the like.

  According to the invention, the at least one additive is generally 0.1 to 40% by weight, preferably 0.2 to 30% by weight, in particular based on the amount of at least one of these monomers, respectively. It is preferably used in an amount of 0.5 to 25% by mass. In the case of a solvent, the amount of the additive may be larger.

  When the solid additive is added, hybrid particulates 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 additive optionally present additionally is, for example, ZnO, ΤiO ₂ , oxidized Fe, such as FeO, Fe ₂ O ₃ and Fe ₃ O ₄ , boric acid and borates, aluminum oxide Metal or metal oxides and / or metalloid oxides selected from silicates, aluminosilicates, SiO ₂ and mixtures thereof. This type of additive is present in particulate form as a solid in the monomer. In a particularly preferred embodiment, the at least one additive, in particular the metal oxide and / or metalloid oxide, is in nanoparticulate form, ie a diameter of 1 to 250 nm, preferably 5 to 100 nm, in particular 10 to 50 nm. Exist. The nanoparticles may have any shape, for example spherical, square, rod-shaped.

  In one embodiment of the present invention, at least one solvent is added to the first aerosol stream. Preferred solvents are those in which at least one of the monomers 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 liquids. Mixtures of the above solvents can also be used.

  Suitable alcohols are, for example, methanol, ethanol, propanols such as n-propanol, isopropanol, butanols such as n-butanol, isobutanol, t-butanol, pentanols, glycerin, glycols 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 propyl acetate and mixtures thereof. Particularly preferably, ethanol or 1-propanol (n-propanol) is used as the solvent.

  When a solvent or solvent mixture is used, the amount of solvent is usually 10 to 80% by volume, preferably 30 to 70% by volume, particularly preferably 40 to 40% by weight, based on the amount of each of the at least one monomer. 60% by volume.

  Suitable additives are also polymers and oils such as 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 polymerization, in which case the polymerization is caused by the action of electromagnetic radiation. Depending on the wavelength used of the electromagnetic radiation, optional additives and materials contained in the second aerosol stream, at least one photoinitiator is present in the monomer for the initiation of the polymerization. Add.

  When at least one photoinitiator is used in the process according to the invention, this photoinitiator is typically added to the monomer droplets of the first aerosol stream. Suitable for this is known to the person skilled in the art which, upon irradiation with electromagnetic radiation, causes a radical or ionic polymerization reaction of at least one monomer used, ie a cationic or anionic polymerization reaction. In principle all photoinitiators. Since the monomer mixture is irradiated with electromagnetic radiation for polymerization, the present invention uses a photoinitiator that liberates a sufficiently large amount of (primary) radicals or cations or anions upon irradiation with electromagnetic radiation. It is preferable to do.

  Within the scope of the present invention, electromagnetic radiation is a type of electromagnetic suitable for initiating the polymerization of at least one of the monomers, optionally using a photoinitiator, within the temperature range of the process according to the invention. Understood to be radiation. The electromagnetic radiation may be X-rays or γ-rays, for example. Preferably, the electromagnetic radiation used according to the invention is ultraviolet 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. Particular preference is given to using ultraviolet light, ie light having a wavelength of at most 400 nm, for example light having a wavelength in the range from 200 to 400 nm, in particular 250 to 350 nm.

  In one embodiment of the invention, the droplets of the first aerosol stream consist essentially of at least one of the monomers and at least one photoinitiator, i.e. at least one of the monomers and at least The concentration of one kind of the photoinitiator is 80 to 100% by mass, preferably 90 to 100% by mass, particularly 95 to 100% by mass, based on the total mass of the droplets.

  An example of a preferred photoinitiator for radical polymerization is 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one (eg under the trade name Irgacure® 907 from BASF SE) Possible), 2,2'-azobisisobutyronitrile (AIBN) and further asymmetric azo derivatives, benzoin, benzoin alkyl ethers, benzoin derivatives, acetophenones, benzyl ketals, α-hydroxyalkylphenones, α-aminoalkyls Phenone, O-acyl-α-oximinoketone, (bi) acylphosphine oxide, thioxanthone (derivative) 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-phenyl-acylpyridinium salts and mixtures thereof.

  So-called living anionic polymerization in pure polymer batches can also be carried out, which optionally nozzles gaseous or evaporable compounds, for example into its aerosol space, preferably into a non-irradiated residence zone Possibly secondary functionalization with a stop reagent.

  In embodiments in which at least one photoinitiator is used, the amount of photoinitiator in the droplets of the first aerosol stream is, for example, about 0. 0, respectively, based on the amount of at least one monomer present. 1-10 mass%, Preferably it is 0.5-8 mass%, Most preferably, it is 0.8-5 mass%.

In a preferred embodiment of the invention, no photoinitiator is added to the first aerosol stream, ie the concentration of photoinitiator in the first aerosol stream is 0.01 mass, based on the total mass of the droplets. %. This embodiment is worth considering if, for example, the solid particles of the second aerosol stream, such as ZnO and / or TiO ₂ , can cause the initiation of photopolymerization in step iv. Optionally, in this embodiment, the photopolymerization can also be triggered by high energy radiation, such as X-rays or gamma rays.

Within the scope of the present invention, generally any solid particles can be used in the second aerosol stream. These may be solid organic compounds, organometallic compounds and inorganic compounds or metals, metalloids and non-metals. Preferably, the solid particles are selected from metal or metalloid oxides, sulfides, carbides, nitrides, carbonates, phosphates and halides, metal carbonyls, elemental metals, elemental metalloids and metal alloys. Has been. Examples are simple metals such as Cu, Ag, Au, Pd, Pt and metalloid or metal oxides, sulfides, nitrides and carbides such as SiO ₂ , SiC, BN, silicates, aluminosilicates, ZnO ZnS, TiO ₂ , Al ₂ O ₃ , metal halides such as NaCl, tungsten oxides such as WO ₂ , WO ₃ and W ₂ O ₃ .

The particles used in the second aerosol stream are, of course, preferably an average particle size 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 in particular in the range from 40 to 500 nm. Fine particle having (number average). The particle size distribution is preferably unimodal, ie the distribution curve has only one local maximum. The width of the distribution is preferably small. In particular, finely divided particles having a narrow distribution width, in particular those having a distribution width Q in the range of 1.0 to 1.2 are used:
_{Q = (D 90 -D 10)} / D 50
D ₅₀ : average particle diameter D ₉₀ : particle diameter below 90% of the particles;
D ₁₀ : Particle size at which 10% of the particles are below.

  The particle sizes shown here and below relate to the particle mass measured using a differential mobility analyzer and the particle size calculated from it assuming spherical particles.

  The provision of the first and second aerosol streams can generally be done by any method known to those skilled in the art or using equipment generally known to those skilled in the art and a suitable carrier gas. . Particularly preferably, the preparation of the aerosol stream is carried out using a one-component or multi-component nozzle in a nebulizer or nebulizer or using an electrospray or ultrasonic nebulizer. If the generation of the aerosol stream is carried out using a nozzle, the nozzle inlet pressure before the nozzle for generating the first and second aerosol streams is generally 1-10 bar, in particular 1 ~ 3 bar.

  It is further possible to adjust to a particularly narrowly distributed droplet distribution or particle size distribution by suitable selection of the nebulizer and its operating conditions or by classification, for example using a differential mobility analyzer (DMA). is there.

The carrier gas streams used to generate the first and second aerosol streams are inert gas streams such as nitrogen (N ₂ ), carbon dioxide (CO ₂ ), argon (Ar), helium (He) and their It may be selected from a mixture, or air or a mixture with air, for example lean air (Magerluft). If the polymerization is initiated and carried out by radicals by the addition of a photoinitiator, an inert gas stream is preferably used. If the polymerization is initiated and carried out by cations, an air stream or an inert gas stream is preferably used. Preferably, the carrier gas stream is an inert gas stream. In particular, N ₂ (nitrogen) is used for the formation of the carrier gas stream. This nitrogen may be derived from all sources known to those skilled in the art, such as in commercially available storage bottles, air distillation and the like. Said other inert gases may likewise be derived from sources known to those skilled in the art. As air, preferably ambient air or compressed air is used.

  The pressure in the carrier gas stream is preferably atmospheric pressure or a slightly elevated atmospheric pressure according to the invention. Within the scope of the present invention, “slightly elevated atmospheric pressure” means a pressure that is, for example, 1 to 500 mbar above atmospheric pressure. This preferably slightly elevated pressure is used in particular for the carrier gas stream to overcome the resistance of downstream device components, such as filters or separate collection liquids.

The first aerosol stream has droplets containing at least one of the monomers in a carrier gas stream. The process according to the invention, generally, a droplet density of the carrier gas stream is, 1 cm ³ per 10 ⁴ -10 ¹⁰ within the droplets, preferably 1 cm ³ per 10 ⁶ to 10 ⁸ within the droplet Very particularly preferably carried out in the range of 10 ⁷ to 10 ⁸ droplets per cm ³ . The droplet density can be measured using, for example, a scanning mobility particle sizer (SMPS) or a condensed particle counter.

  The amount of at least one monomer and optionally at least one photoinitiator and optionally at least one non-polymerizable additive introduced into the carrier gas stream is according to the invention per volume. It is calculated to obtain a corresponding number of particles. With the amount of at least one monomer, it is possible to calculate the size of the 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 in particular in the range of 30 to 500 nm. Adjustment of the droplet diameter is typically performed by selection of operating conditions of the nebulizer, for example, by the inlet pressure before the nebulizer, the ratio of mass flow rates of gas and liquid, and the like. In the case of an electrospray process, for example, the voltage can be changed, and in the case of an ultrasonic nebulizer, the energy supply can be changed. In addition, a specific size fraction can be selected by DMA.

  In order to provide a second aerosol stream, typically a suspension of the solid particles is transferred into the aerosol stream using a gas. The suspension used to prepare the second aerosol stream generally has a solids content of 0.01 to 10 mg / mL, preferably 0.1 to 3 mg / mL. As liquid suspension medium, a large number of liquids can be used, preferably liquids having boiling points in the range of 30 to 120 ° C. and in particular in the range of 40 to 100 ° C. at normal pressure. Preferred liquids are polar solvents such as water, alkanols such as methanol, ethanol, n-propanol, isopropanol, but are also hydrocarbons. Mixtures of different solvents can also be used. In particular, water is used.

  The aerosol of the second aerosol stream containing water, generated during the use of water as a solvent, is directed to a suitable dryer, such as a diffusion dryer, after which the solvent, generally water, is removed. The

  In one embodiment, other mechanical devices such as brush feeders can be used for spraying the solid particles.

  It is also possible to generate solid particles of the second aerosol stream from droplets of the upstream aerosol stream. Typically, this involves producing a solution of a material, such as sodium chloride, that later forms solid particles of a second aerosol stream in a solvent, such as water. This mixture is sprayed, for example in a two-fluid nozzle, using a carrier gas stream, for example nitrogen, at a nozzle inlet pressure of 1 bar. The resulting aerosol is directed to a dryer, such as a diffusion dryer, where the solvent, such as water, is significantly or completely removed. In this way, an aerosol stream of solid particles, for example nanoscale sodium chloride particles, is obtained from the droplets of the upstream aerosol stream. This aerosol stream of solid particles is preferably used in the process according to the invention as a second aerosol stream without intermediate isolation.

The second aerosol stream provided by the present invention contains solid particles in the carrier gas stream. The process according to the invention, generally, the particle density of the carrier gas stream is in the range of 1 cm ³ per 10 ⁴ to 10 ¹⁰ particles, preferably in the range of 1 cm ³ per 10 ⁴ to 10 ⁸ particles, very particularly Preferably it is carried out to be in the range of 10 ⁴ to 10 ⁶ particles per cm ³ . The particle density can be measured, for example, using a scanning mobility particle sizer (SMPS) or a condensed particle counter.

  According to the present invention, the droplets of the first aerosol stream and the particles of the second aerosol stream are oppositely charged prior to their mixing. The droplets of the first aerosol stream can be negatively charged as well as positive. The solid particles of the second aerosol stream are oppositely charged. In a particular 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.

  In order to prepare a first aerosol stream having charged droplets containing at least one monomer, it is customary first to initially contain at least one monomer and essentially no charge. An aerosol stream of droplets is generated and this aerosol stream is directed to a charging device, such as a corona charging device, for charging the droplets.

  Correspondingly, the preparation of the second aerosol stream is typically first of all generating an essentially uncharged particle aerosol stream, which is used for charging the droplets by means of a charging device, For example, it is carried out by leading to a corona charging device. The corona charging device is based on the principle of gas discharge by applying a high voltage. When the voltage is sufficiently high, a gas discharge and a strong electric field are formed. Depending on the size of the particles used, either electric field charging or diffusion charging can be performed. For particles having a diameter of 1 μm or more, the electric field charging mechanism is dominant. Ions generated due to gas discharge move along the lines of force. When these field lines end on the particle surface, ions collide and a particle charge is generated. For smaller particle sizes (<1 μm), the ions collide with the particles (diffusion charging) based on stochastic motion. This process is further performed after leaving the charging device. By selecting and adjusting the process conditions in the charging device, the particles or droplets can be unipolarly charged in a tailored manner and the charge density in the aerosol stream can be adjusted.

  The aerosol of the first aerosol stream is charged monopolar, preferably negative, using the charging device.

  The aerosol of the second aerosol stream is charged using a charging device, likewise monopolar and opposite to the first aerosol stream, ie preferably positive. As a charging device for the second aerosol flow, a charging device (bipolar charging device) having a UV charging device or a radiation source can be used in addition to the corona charging device already mentioned. UV charging devices offer the additional possibility of producing aerosols with a unipolar charge. When the high energy photons collide with the aerosol particles, electrons are emitted and the positively charged particles are left behind. This light effect depends on the material to be charged and the wavelength of the radiation. Unipolar charging of the particles of the second aerosol stream is also achieved using a radiation source such as Kr85. Upon radioactive decay, ionizing radiation is generated that produces negative as well as positive ions. This ionic mixture generates a Boltzmann charge distribution distributed around zero charges. As the aerosol particle diameter increases, the probability of multiple charges also increases. A corona charging device is preferred for unipolar charging of the aerosol in the second aerosol stream.

  Preferably, the charging device is configured such that a spray electrode to which a high voltage is applied exists therein. Preferably, the voltage on the spray electrode of the charging device is 2-6 kV, in particular 2-4 kV, for the first aerosol stream. Preferably, the voltage on the spray electrode of the charging device is 2-6 kV, especially 3-5 kV, for the second aerosol stream.

  The volume ratio of the first aerosol stream to the second aerosol stream is generally such that the ratio of the volume flow rate of the first aerosol stream to the volume flow rate of the second aerosol stream is in the range of 8: 1 to 1: 8, especially 3: It is selected to be within the range of 1-1: 3.

  In the process according to the invention, a first aerosol stream containing droplets of at least one monomer, optionally containing at least one photoinitiator and optionally containing at least one additive is a solid When mixed with a second aerosol stream containing particles, a mixed aerosol stream is obtained. The mixing is carried out by measures such as known for the mixing of gas or aerosol streams, for example by directing both aerosol streams into the mixing zone or combining the two aerosol streams in a suitable manner. Can be done. The mixing zone may be designed as a mixing chamber, for example. In this case, both the aerosol streams are led into the mixing chamber and the mixed aerosol stream is removed from the mixing chamber. The mixing zone may be designed as a tubular zone, i.e. as a mixing zone. In this case, the two aerosol streams can be combined in a suitable manner in a tubular zone, for example, into a zone designed into a tubular shape together, for example via a Y- or T-joint. Unite by supplying. Mixing within the mixing zone or section can be facilitated by internal components known to those skilled in the art, such as static mixers.

  The mixing zone or section extends in a preferred embodiment in the form of a non-irradiated residence zone. This residence zone facilitates the assembly of particles with different charges, resulting in finely divided core-shell particles having a solid shell in addition to a liquid shell containing the monomer. Subsequently, polymerization of the monomer is then initiated in the polymerization zone, whereupon the shell of the fine core-shell particles is solidified. Preferably, the mean residence time of the mixed aerosol stream in the unirradiated residence zone is in the range of 1 to 500 seconds, in particular in the range of 10 to 100 seconds.

  The mixed aerosol stream thus obtained is subsequently irradiated with electromagnetic radiation, for example light, preferably ultraviolet light, or high energy radiation, so that the monomer present polymerizes. The irradiation is of course carried out in a reaction zone, also referred to below as a photoreactor, downstream of the mixing zone.

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

Irradiation of electromagnetic radiation to the carrier gas stream according to the present invention can generally be performed in any apparatus known to those skilled in the art. According to the invention, preferably ultraviolet light is used. This is achieved by all devices known to the person skilled in the art, for example LEDs, excimer emitters, for example as radioactive media 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 Xe ₂ (172 nm), for example having 10 mW / cm ² on the emitter surface, or using a UV fluorescent tube, for example It can be generated with 8 mW / cm ² on the radiator surface. The use of excimer emitters is advantageous because it can be dimmed, for example to 10 to 100%, by pulsing. Thereby, the optimization of the polymerization process is relatively simple.

In a preferred embodiment of the process according to the invention, the inner wall of the light reactor, air, a lean air or an inert gas, for example _{N 2, Ar, He, CO} 2 or mixtures thereof, is flushed. This is useful, for example, in suppressing wall loss due to polymer film formation.

  In a further embodiment of the method according to the invention, it is additionally possible to nozzle a reactive gas for 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 temperatures in the range from 0 to 100 ° C., in particular in the range from 10 to 50 ° C., in particular in the range from 20 to 30 ° C.

  Therefore, according to the present invention, after leaving the photoreactor, which is preferably used, the polymerization inside the particulates is essentially complete, so that the corresponding particulates having a core-shell structure. And the particles have a solid surface and therefore no longer change during further processing steps, for example separation of the formed fine particles. The finely divided particles obtained according to the invention have a core-shell structure, i.e. the core of the finely divided core-shell particles consists of solid particles of a second aerosol stream, and the shell comprises polymerized monomers and Optionally comprising at least one non-polymerizable additive in the first aerosol stream. The finely divided particles obtained by the present invention are particularly excellent in a uniform core-shell structure. A further advantage is that the size of the droplets and the size of the solid particles predetermine the size of the core-shell particles produced. By adjusting the droplet size via the nebulizer, it is therefore possible to directly adjust the resulting particle size and shell thickness.

  In a further processing step, the formed fine particles can be separated from the carrier gas. The separation can in principle be carried out by all methods known to those skilled in the art. In a preferred embodiment, the formed fine particles are separated by separating and collecting with a filter, and in a more preferred embodiment, by introducing into a liquid medium. Separation and collection in a liquid can be performed using, for example, a bottle or a wet electric filter.

  The liquid medium optionally used for the separation and collection may be selected from water, ethanol, organic solvents such as all types of nonpolar solvents such as alkanes, cycloalkanes and mixtures thereof. By introducing the produced fine particles into the liquid medium, a suspension of the fine particles in the liquid medium is obtained. This suspension can be further processed in order to obtain the particles, for example by separation of the finely divided particles from the suspension, or the suspension can be processed as desired according to the invention. Product and can be directly introduced into the corresponding application. For long-term maintenance of the resulting particle size, further additives can be added that stabilize the particles against agglomeration in order to avoid agglomeration of the resulting core-shell particles.

  The separation and collection of the fine particles can also be carried out using a filter. Suitable filters are known per se to the person skilled in the art and are, for example, polyamide filters, polycarbonate filters, PTFE filters, for example those having a pore size of 50 nm, electrical filters.

  By means of the process according to the invention, finely divided particles having a core-shell structure are available, in which the shell comprises at least one polymer and / or copolymer formed from monomers of the first aerosol stream. According to the invention, the concept of “fine particles” is the number average particle size in the range 25 nm to 30 μm, often in the range 25 nm to 10 μm, in particular in the range 30 nm to 1 μm and in particular in the range 40 to 500 nm. It should be understood as a particle having a diameter.

  The process according to the invention, of course, provides a composition containing a large number of these fine particles. The average particle size and particle size distribution of the fine particles in these compositions is, of course, determined by the particle size distribution of the particles in the second aerosol stream. The particle size distribution is preferably unimodal, ie the distribution curve has only one local maximum. The width of the distribution is preferably small. Thus, the distribution width Q having a value in the range of 1.0 to 1.2 can be realized using the method according to the invention.

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

  The subject of the invention is also a composition of finely divided particles, for example a dispersion of finely divided particles and a powder of finely divided particles, in which the finely divided particles are selected from among the finely divided particles according to the invention. ing.

  The core of fine particles having a core-shell structure is generally formed from a solid organic material, an inorganic material or an organometallic material. The core of the core-shell particles is generally on average from 1 to 99.9% by volume, in particular from 10 to 95% by volume, in particular from 50 to 90% by volume, based on the total volume of the particles.

  The average molecular weight of the uncrosslinked polymer shell of the core-shell particles can be measured using GPC. The number average molecular weight of the polymer shell is generally 1000 to 1000000 g / mol, often 5000 to 100000 g / mol, in particular 10000 to 80000 g / mol, in particular 10000 to 60000 g / mol.

  The process according to the invention can be configured as a batch process or continuously. Preferably, the process according to the invention is carried out continuously.

4 is a TEM image of fine particles having a core-shell structure obtained in Example 1. FIG. 4 is a TEM image of fine particles having a core-shell structure obtained in Example 1. FIG. 4 is a TEM image of fine particles having a core-shell structure obtained in Example 2. 4 is a TEM image of fine particles having a core-shell structure obtained in Example 3. 4 is a TEM image of fine particles having a core-shell structure obtained in Example 4. 6 is a TEM image of fine particles having a core-shell structure obtained in Example 5.

Analysis method:
Transmission electron microscopy (TEM) can be used to visualize the core and shell of the core-shell particles. Fourier transform infrared spectroscopy (FTIR) is a spectroscopic method in which double bonds of the monomer molecules are not present in the polymer structure or the liquid monomer layer is a solid polymer. Used to show. The average molecular weight of the polymer shell can be measured using gel permeation chromatography (GPC).

General experimental procedure:
In order to generate a first aerosol stream, a solution of at least one monomer, optionally at least one photoinitiator, optionally at least one additive and optionally at least one crosslinking agent is added to the carrier gas. A stream is used to feed into the nebulizer (a nebulizer with a two-fluid nozzle, Topas, model ATM 220). After exiting the nebulizer, the aerosol is charged in a corona charging device.

  In order to generate a second aerosol stream, a suspension of the solid particles, for example in water, is used with the carrier gas stream into a nebulizer (a nebulizer with a two-fluid nozzle, Topas, model ATM 220). Supply. Subsequently, the aerosol is passed through a diffusion dryer (Topas, model DDU 570 / H) to minimize the water content of the aerosol. After leaving the nebulizer, the aerosol is charged in the corona charging device to a charge opposite to the first aerosol stream.

  In order to generate a second aerosol stream of solid sodium chloride particles in Examples 4 and 5, a second aerosol stream is prepared according to the following rules: Chloride in water having a solids content of 3.5 mg sodium chloride per mL of water. A solution of sodium is prepared. This mixture is sprayed using the carrier gas stream in a two-fluid nozzle with a nozzle inlet pressure of 1 bar. The generated aerosol consisting of sodium chloride-containing water droplets is directed to a diffusion dryer. After exiting the diffusion dryer, a second aerosol stream of solid nanoscale sodium chloride particles is obtained, which is charged in a corona charging device to a charge opposite to the first aerosol stream.

The first and second aerosol streams are merged and run in a darkened residence zone. Subsequently, the mixed aerosol stream is flowed to one of two self-made photoreactors, photoreactors 1 or 2 (photoreactor 1 as a UV source, 10 mW / cm on the emitter surface). ^It has a XeCl excimer emitter with a photon output of ^{2. In} this photoreactor, the UV emitter is centrally located so that the irradiation is directed outwards. Composed of three identical UV emitters, each equipped with a UV fluorescent tube and having a photon output of 8 mW / cm ² on the emitter surface, in which the UV emitter is Since it is outside the reaction volume, the irradiation is done inward).

In all examples, nitrogen (N ₂ ) 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 silicon dioxide, particle size 250nm (Manufacturer: Microparticles)
-Almost spherical nanoscale gold, particle size 100nm (Manufacturer: Postnova)
Nanoscale zinc oxide: 40% by mass of zinc oxide nanoparticles in ethanol, particle size of 30 nm (manufacturer: Sigma Aldrich)
Sodium chloride.

Example 1:
First aerosol flow:
Monomer: Methyl methacrylate photoinitiator: Irgacure (registered trademark) 907, 1% by mass in methyl methacrylate
Cross-linking agent: 10% by volume based on the amount of 1,6-hexanediol diacrylate and methyl methacrylate
Nozzle inlet pressure: 1 bar
Charging voltage: 2 kV
Polarity of the droplets: concentration of the monomer droplets in the negative aerosol: 10 ⁷ to 10 ⁸ droplets / cm ³
Average droplet diameter: 131.4 nm, standard deviation 0.57 μm
Elementary quantity per droplet: 10-60, second aerosol flow depending on diameter:
Solid: Spherical nanoscale silicon dioxide Concentration: 1 mg of SiO ₂ per mL of H ₂ O
Nozzle inlet pressure: 2 bar
Charging voltage: 4 kV
Polarity of the particles: Concentration of the particles in the positive aerosol: 10 ⁵ particles / cm ³
Average particle size: 250 nm, standard deviation 0.1 μm
Electric quantity per particle: 40
Mixed aerosol flow:
Residence time in residence zone not irradiated: 10 seconds Irradiation period: 3 Spectral reactor: Photoreactor 1.

Example 2:
First aerosol flow:
Monomer: Methyl methacrylate photoinitiator: Irgacure (registered trademark) 907, 1% by mass in methyl methacrylate
Cross-linking agent: 10% by volume based on the amount of 1,6-hexanediol diacrylate and methyl methacrylate
Nozzle inlet pressure: 1 bar
Charging voltage: 2 kV
Polarity of the droplets: concentration of the monomer droplets in the negative aerosol: 10 ⁷ to 10 ⁸ droplets / cm ³
Average droplet diameter: 131.4 nm, standard deviation 0.57 μm
Elementary quantity per droplet: 10-60, second aerosol flow depending on diameter:
Solid: almost spherical nanoscale gold concentration: 0.6 mg Au per mL of H ₂ O
Nozzle inlet pressure: 2 bar
Charging voltage: 4 kV
Polarity of the particles: Concentration of the particles in the positive aerosol: 10 ⁵ particles / cm ³
Average particle size: 100 nm
Electric quantity per particle: 20
Mixed aerosol flow:
Residence time in residence zone not irradiated: 10 seconds Irradiation period: 3 Spectral reactor: Photoreactor 2

Example 3:
First aerosol flow:
Monomer: Methyl methacrylate photoinitiator: Irgacure (registered trademark) 907, 1% by mass in methyl methacrylate
Cross-linking agent: 10% by volume based on the amount of 1,6-hexanediol diacrylate and methyl methacrylate
Ethanol: 0.2 mL of a suspension of zinc oxide nanoparticles in ethanol per 15 ml of methyl methacrylate, this suspension is added to the monomer solution.
Nozzle inlet pressure: 1 bar
Charging voltage: 2 kV
Polarity of the droplets: concentration of the monomer droplets in the negative aerosol: 10 ⁷ to 10 ⁸ droplets / cm ³
Average droplet diameter: 131.4 nm, standard deviation 0.57 μm
Elementary quantity per droplet: 10-60, second aerosol flow depending on diameter:
Solid: Spherical nanoscale silicon dioxide Concentration: 1 mg of SiO ₂ per mL of H ₂ O
Nozzle inlet pressure: 2 bar
Charging voltage: 4 kV
Polarity of the particles: Concentration of the particles in the positive aerosol: 10 ⁵ particles / cm ³
Average particle size: 250 nm, standard deviation 0.1 μm
Electric quantity per particle: 40
Mixed aerosol flow:
Residence time in residence zone not irradiated: 10 seconds Irradiation period: 3 Spectral reactor: Photoreactor 2

Example 4:
First aerosol flow:
Monomer: Methyl methacrylate photoinitiator: Irgacure (registered trademark) 907, 1% by mass in methyl methacrylate
Cross-linking agent: 10% by volume based on the amount of 1,6-hexanediol diacrylate and methyl methacrylate
Nozzle inlet pressure: 1 bar
Charging voltage: 3.5 kV
Polarity of the droplets: Concentration of the monomer droplets in the negative aerosol: about 10 ⁷ droplets / cm ³
Average droplet diameter: about 130 nm
Elementary electric charge per droplet: about 10-60, depending on diameter, second aerosol flow:
Solid: Nanoscale sodium chloride nozzle inlet pressure: 2 bar
Charging voltage: 4 kV
Polarity of the particles: Concentration of the particles in the positive aerosol: about 10 ⁷ particles / cm ³
Average particle diameter: about 65nm
Elementary quantity of electricity per particle: about 10-60, depending on diameter, mixed aerosol flow:
Residence time in residence zone not irradiated: 60 seconds Irradiation period: 3 Spectral reactor: Photoreactor 2

Example 5:
First aerosol flow:
Monomer: 1,6-hexanediol diacrylate photoinitiator: Irgacure (registered trademark) 907, 1% by mass in 1,6-hexanediol diacrylate
Crosslinker:-
Nozzle inlet pressure: 1 bar
Charging voltage: 3.5 kV
Polarity of the droplets: Concentration of the monomer droplets in the negative aerosol: about 10 ⁷ droplets / cm ³
Average droplet diameter: about 130 nm
Elementary electric charge per droplet: about 10-60, depending on diameter, second aerosol flow:
Solid: Nanoscale sodium chloride nozzle inlet pressure: 2 bar
Charging voltage: 4 kV
Polarity of the particles: Concentration of the particles in the positive aerosol: about 10 ⁷ particles / cm ³
Average particle diameter: about 65nm
Elementary quantity of electricity per particle: about 10-60, depending on diameter, mixed aerosol flow:
Residence time in residence zone not irradiated: 60 seconds Irradiation period: 3 Spectral reactor: Photoreactor 2

Example 6:
Fine particulate particles having a core-shell structure were prepared in a manner similar to that performed in Example 1. N-Butyl acrylate was used as the monomer in the first aerosol stream. A photoinitiator was used, but no crosslinker was used. The solid in the second aerosol stream was spherical nanoscale silicon dioxide.

  Fine particles having a shell made of poly-n-butyl acrylate and having a core made of spherical nanoscale silicon dioxide were obtained.

  Since no cross-linking agent was added, the shell of the fine particles having a core-shell structure was not seen in the TEM image.

Claims (23)

A method for producing finely divided particles having a core-shell structure, wherein the shell comprises at least one polymer,
The method comprises the following steps:
i. Providing a first aerosol stream of droplets in a carrier gas stream and charging the droplets of the first aerosol, wherein the droplets contain at least one monomer;
ii. Providing a second aerosol stream of solid particles in a carrier gas stream and charging the solid particles of the aerosol with a charge opposite to the charge of the droplets of the first aerosol stream;
iii. Mixing a first aerosol stream with a second aerosol stream to obtain a mixed aerosol stream;
iv. A method for producing finely divided particles having a core-shell structure, comprising the step of initiating polymerization of the monomer by irradiating the mixed aerosol stream with electromagnetic radiation.   The method of claim 1, wherein the droplets of the first aerosol stream consist essentially of at least one of the monomers and at least one photoinitiator.   The method of claim 1 wherein the droplets of the first aerosol stream additionally contain at least one non-polymerizable additive.   4. A method as claimed in claim 1, wherein the droplets of the first aerosol stream have a number average droplet diameter in the range of 20 nm to 30 [mu] m, in particular in the range of 30 nm to 1000 nm. 5. The method according to claim 1, wherein the first aerosol stream has a droplet density in the range of 10 ⁴ to 10 ¹⁰ droplets per cm ³ , in particular in the range of 10 ⁶ to 10 ⁸ droplets. the method of.   6. A process according to any one of the preceding claims, wherein the at least one monomer is selected from olefinically unsaturated monomers and cyclic ethers, lactones and lactams.   The at least one monomer is selected from monoolefinically unsaturated monomers and mixtures of at least one monoolefinically unsaturated monomer and at least one polyolefinically unsaturated monomer. The method according to any one of 6 to 6. At least one of said monomers, monoolefinically unsaturated C ₃ -C ₆ - monocarboxylic acids, monoolefinic unsaturated C ₄ -C ₆ - dicarboxylic acid, mono-olefinically unsaturated C ₃ -C ₆ - monocarboxylic Esters of acids, monoolefinically unsaturated C ₄ -C ₆ -dicarboxylic acid esters, monoolefinically unsaturated C ₃ -C ₆ -monocarboxylic acid amides, N-vinyl amides, N-vinyl lactams, vinyl aromatic compounds , Vinyl ether, vinyl ester, allyl ester and methallyl ester, monoolefinically unsaturated nitrile, α-olefin, monoolefinically unsaturated sulfonic acid, monoolefinically unsaturated phosphonic acid and monoolefinically unsaturated phosphoric acid half ester Comprising at least one monoolefinically unsaturated monomer selected from Claim 6 or 7 The method according.   First, an aerosol stream of droplets containing at least one monomer and having essentially no charge is generated, and this aerosol stream is directed to a charging device for charging the droplets. 9. A method according to any one of claims 1-8.   10. The method according to claim 1, wherein the particles of the second aerosol stream have a number average particle size in the range of 20 nm to 30 μm, in particular in the range of 30 nm to 1000 nm. The second aerosol stream, 1 cm ³ per 10 ⁴ to 10 ¹⁰ particles, in particular having a particle density in the range of 1 cm ³ per 10 ⁴ to 10 ⁶ particles, the method of any one of claims 1 to 10.   12. A method according to any one of the preceding claims, wherein the particles of the second aerosol stream consist of at least one solid organic material, inorganic material or organometallic material.   The particles of the second aerosol stream are selected from metal or metalloid oxides, sulfides, carbides, nitrides, carbonates, phosphates and halides, metal carbonyls, elemental metals, elemental metalloids and metal alloys. The method according to claim 12, wherein the method is made of a material that has been prepared.   14. A method according to any one of the preceding claims, wherein the mixed aerosol stream is directed to a non-irradiated residence zone prior to irradiation with electromagnetic radiation.   15. A process according to claim 14, wherein the average residence time of the mixed aerosol stream in the residence zone is in the range 1 to 500 seconds, in particular in the range 10 to 100 seconds.   16. A process according to any one of claims 1 to 15, wherein the mixed aerosol stream is directed to a flow-through photoreactor for polymerization.   The process according to claim 16, wherein the mean residence time of the mixed aerosol stream in the flow-through photoreactor is in the range of 1 to 300 seconds, in particular in the range of 5 to 60 seconds.   The method according to claim 1, wherein fine particles having a core-shell structure are separated and collected on a filter or a surface after photopolymerization.   The method according to any one of claims 1 to 18, wherein after the photopolymerization, fine particles having a core-shell structure are separated and collected by introducing the aerosol flow into a liquid medium.   A fine particle having a core-shell structure obtained by the method according to any one of claims 1 to 19.   21. Fine particulate particles according to claim 20, having a number average particle size in the range of 25 nm to 30 [mu] m, in particular in the range of 30 nm to 1 [mu] m.   The finely divided particle according to claim 20 or 21, wherein the core is formed of a solid organic material, an inorganic material, or an organometallic material.   The core of the core-shell particles averages from 1 to 99.9% by volume, in particular from 10 to 95% by volume, in particular from 50 to 90% by volume, based on the total volume of the particles. The finely divided particles according to any one of up to 22.

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