WO2011154421A1

WO2011154421A1 - Microcapsules containing active substance and having a metal oxide-containing shell

Info

Publication number: WO2011154421A1
Application number: PCT/EP2011/059423
Authority: WO
Inventors: Jing Dreher; Matthias Laubender; Michael Kutschera
Original assignee: Basf Se
Priority date: 2010-06-09
Filing date: 2011-06-08
Publication date: 2011-12-15

Abstract

The invention relates to microcapsules which have a core-shell structure, contain at least one low-molecular, anionic surfactant and comprise a metal oxide-containing shell. The invention also relates to a method for producing these microcapsules having a core-shell structure, the use of the microcapsules having the core-shell structure, and preparations containing the microcapsules having the core-shell structure.

Description

The present invention relates to microcapsules having a core-shell structure containing at least one low molecular weight, anionic surfactant and having a metal oxide-containing shell, a process for producing such microcapsules having a core-shell structure , the use of microcapsules with the core-shell construction and preparations containing the microcapsules with the core-shell construction.

The encapsulation of drugs is done for a variety of reasons. For example, the encapsulation can increase the storage stability of those substances that are sensitive to light, oxygen or moisture. In the case of pharmaceutical active ingredients, the encapsulation can specifically influence the release of active ingredient. Or liquid substances can be handled after encapsulation in the form of a free-flowing powder. In the field of detergents and cleaners or textile care agents, the encapsulation of flavorings, flavors or fragrances serves firstly to prevent a reaction of these encapsulated substances with atmospheric oxygen or other chemicals present in the formulations, such as, for example, bleaching agents. Another problem is the sometimes high volatility of the fragrances or fragrances, which means that a large part of the originally added to the detergent or cleaning agent fragrance or fragrance has volatilized before the date of use. To overcome the mentioned problems, it has already been proposed to incorporate the fragrances or fragrances in microencapsulated form into the washing or cleaning agents. Such microcapsules have already been described.

WO 2005/009604 A1 describes microcapsules with a high active ingredient content, in which a core containing an active substance is enveloped by a shell, wherein the shell comprises an inorganic polymer.

In WO 2007/015243 a process for the preparation of microcapsules is described in which solid hydrophobic active ingredients are enveloped by several shells of silica gel.

In DE 10 2008 030 662 coated fragrance and / or aroma particles are described, each containing a particle core containing silicates and fragrances and / or flavors and a shell containing water-soluble silicates. WO 2009/090169 describes microcapsules whose core contains a fragrance or perfume and whose shell is formed by polymerization of acrylic and / or methacetic acid. rylsäureestern and at least two different bi- or polyfunctional monomers was constructed.

Despite the prior art described above, there is still a need for capsules which exhibit improved stability against accidental rupture of the shell or which have a denser, less porous shell to prevent leakage or volatilization of the active agent. On the other hand, the shell must not be so stable that a release of fragrances or fragrances under normal mechanical stress hardly or not at all takes place. Furthermore, the capsules should contain no unwanted by-products, such as residues of unreacted monomers. Finally, the process for the preparation of the capsules should be as widely used and easy to carry out. The process for making the capsules should be stable to both thermal and mechanical stresses.

The object of the present invention was therefore to provide active ingredient-containing capsules with improved stability with regard to the protection of the active ingredient against undesirable volatilization and to be able to produce the novel active ingredient-containing capsules by a simple and robust process.

This object is achieved by microcapsules having a core-shell structure containing at least one low molecular weight anionic surfactant, wherein each microcapsule internally contains a core containing at least one sparingly water-soluble or water-insoluble organic active substance and a shell directly around the core. has, wherein the shell comprises at least one metal oxide and at least one water-soluble polymer dissolved.

The mass fraction of the core in relation to the total mass of the microcapsules according to the invention is usually greater than 10% by weight, preferably greater than 20% by weight, particularly preferably in the range from 25 to 80% by weight, very particularly preferably in the range from From 30 to 60% by weight. The percentages refer to a statistical average determined over a large number of microcapsules.

The microcapsules according to the invention having a core-shell structure each contain a core in the interior which comprises at least one organic substance which is sparingly soluble in water or insoluble in water. The core can be both liquid and solid at 20 ° C. If the core is a solid at 20 ° C, this solid may be crystalline, semi-crystalline or amorphous. If the core is a liquid at 20 ° C, this liquid may be a homogeneous phase or a suspension. The core of the microcapsules according to the invention is preferably a liquid at 20 ° C. The core in the interior of the microcapsules according to the invention often contains, in addition to the at least one sparingly water-soluble or water-insoluble organic active ingredient, at least one sparingly water-soluble or water-insoluble organic adjuvant, for example for concentration of the active ingredient, for altering the release profile of the active ingredient or simply for dissolving or suspending the Active ingredient serves. Therefore, the concentration of the active ingredient in the core of the microcapsules according to the invention can be varied over a wide range according to the field of use and the properties of the active ingredient, such as its solubility in the organic adjuvant.

Due to its composition, the core preferably exhibits hydrophobic properties, that is to say that the core is only sparingly water-soluble or water-insoluble.

The microcapsules according to the invention usually have an average particle size (d 50 value) of less than 100 μm, preferably less than 10 μm, particularly preferably an average particle size of from 0.05 μm to 5 μm, in particular from 0.1 μm to 2 μm ,

The d50 value is defined by that 50% by weight of the particles have a diameter smaller and 50% by weight of the particles have a diameter greater than the value corresponding to the d50 value. The d50 value can be read off from a particle size distribution curve, such as can be generated, for example, by means of light scattering in accordance with ISO 13320-1 (for example Microtrac S3500 Bluewave from Microtrac).

The microcapsules according to the invention particularly preferably have an average particle size of less than 2 μm.

The average particle size of the microcapsules and the thickness of the shells can be determined by means of TEM (transmission electron microscopy). The average particle size can be determined by the methods of light scattering (static and dynamic light scattering).

The shape of the cores in the microcapsules according to the invention is arbitrary and may be, for example, irregular or spherical, preferably spherical.

The microcapsules of the invention having a core-shell structure contain at least one low molecular weight, anionic surfactant, the molar mass of the low molecular weight, anionic surfactants usually being less than 1000 g / mol, preferably less than 500 g / mol. Anionic surfactants have, in addition to a nonpolar, fat-soluble part, a polar, negatively charged part, such as a carboxylate radical, a sulfonate radical, a sulfate radical or a phosphate radical. Typical representatives for low Examples of molecular anionic surfactants are alkylcarboxylates, alkylbenzenesulfonates, secondary alkanesulfonates, alkylphenol sulfate or fatty alcohol sulfates. Typical representatives for the various classes of anionic surfactants are listed in WO 2009/090169, page 10, line 37 to page 12, line 6. Particularly preferred are microcapsules in which the low molecular weight, anionic surfactant is a fatty alcohol sulfate or an alkylphenol ether sulfate. The salts of the preferred fatty alcohol sulfates have the formula: C _n H 2n + iOS03 ^~ M ⁺ n is from 8 to 18, in particular 10 to 16, and M is Na or K, in particular Na. With particular preference, the microcapsules according to the invention having a core-shell structure additionally contain at least one nonionic surfactant in addition to the at least one low molecular weight, anionic surfactant. Nonionic surfactants are surface-active substances with an uncharged, in the neutral pH range no ion charge-carrying, polar, hydrophilic, water-solubilizing head group (in contrast to anionic see and cationic surfactants) adsorbed at interfaces and above the critical micelle concentration (eme) to aggregated to neutral micelles. Depending on the type of hydrophilic head group, it is possible to distinguish between (oligo) oxyalkylene groups, in particular (oligo) oxyethylene groups (polyethylene glycol groups), including the fatty alcohol polyglycol ethers, fatty alcohols, alkylphenol polyglycol ethers, fatty acid ethoxylates, alkoxylated triglycerides and mixed ethers (alkylated on both sides). ethylene glycol ethers); and carbohydrate groups, which include, for. As the alkyl polyglucosides and fatty acid N-methylglucamide count. Typical representatives for the various classes of nonionic surfactants are listed in WO 2009/090169, page 13, line 17 to page 15, line 9.

Particularly preferred nonionic surfactants are sorbitan fatty acid esters with poly- ethylenglycolresten, so-called polysorbates (Tween ^® types), such as polyvinyl lyoxyethylen (20) sorbitan monolaurate.

Preferably, the weight ratio between the anionic surfactant, in particular a fatty alcohol sulfate of the formula C _n H2n + iOS03 ^~ M ⁺ , and the nonionic surfactant, 1: 1 to 5: 1, more preferably 1: 1 to 3: 1.

In the preparation of the microcapsules according to the invention, the proportion by weight of the surfactants used, based on the mass of the oil phase, is preferably in the range from 0.5% to 20%, in particular in the range from 1% to 5%.

As sparingly water-soluble or water-insoluble organic active substance, organic compounds are used which are used, for example, in the food and animal nutrition sector, for pharmaceutical and cosmetic applications, in the field of crop protection, in laundry detergents and cleaners, in textile care products or in the field of plastic additives , However, the sparingly water soluble or water insoluble organic active may also be an explosive, a wax or an insect repellent. The microcapsules according to the invention can be used advantageously in all the applications in which the active ingredient is to be temporarily or permanently separated from the environment. The organic agents are chemical compounds that usually contain both carbon and hydrogen.

A sparingly water-soluble organic active substance is usually a chemical compound whose solubility in water at 20 ° C. is less than 10 g / l, preferably less than 1 g / l, particularly preferably less than 0.1 g / l.

Active ingredients used in the food and animal nutrition sector include lipophilic vitamins such as tocopherol, vitamin A and its derivatives, vitamin D and its derivatives, vitamin K and its derivatives, vitamin F and its derivatives, or saturated and unsaturated fatty acids Derivatives and compounds thereof, natural and synthetic flavorings, flavors and fragrances and lipophilic dyes, such as retinoids, flavonoids or carotenoids. Active substances used in the pharmaceutical sector include anesthetics and narcotics, anticholinergics, antidepressants, psychostimulants and neuroleptics, antiepileptics, antimycotics, antiphlogistics, bronchodilators, cardiovascular drugs, cytostatics, hyperemics, lipid-lowering drugs, spasmolytics, testosterone derivatives, tranquilizers or antivirals.

Active ingredients used in the field of cosmetics include perfume oils, organic UV filters, dyes, organic pigments or care agents such as vitamin E acetate. Preferred dyes which can be used as active ingredients in the microcapsules according to the invention are natural or synthetic dyes which are approved in the field of nutrition or cosmetics, as described, for example, in WO 2005/009604 A1 on page 9, lines 18 to 30 , Crop protection agents are lipophilic agrochemicals such as insecticides, fungicides, pesticides, nematicides, rodenticides, molluscicides, growth regulators and herbicides.

The term pesticide (or agrochemical active ingredient) denotes at least one active substance selected from the group of fungicides, insecticides, nematicides, herbicides, rodenticides, safeners and / or growth regulators. Preferred pesticides are fungicides, insecticides, rodenticides and herbicides. Also mixtures of pesticides Two or more of the above classes may be used. One skilled in the art will be familiar with such pesticides as described, for example, in Pesticide Manual, 14th Ed. (2006), The British Crop Protection Council, London. Active ingredients which are used in the field of detergents and cleaners or textile care agents are, for example, flavorings or fragrances, disinfectants, dyes, bleaches, biocides, organic solvents or perfumes.

Active substances used in the field of plastic additives are, for example, light stabilizers, such as UV stabilizers, flame retardants or antioxidants.

The sparingly water-soluble or water-insoluble organic active substance which is contained in the core of the microcapsules according to the invention is preferably an aroma chemical, in particular a flavoring, fragrance or fragrance substance.

An aroma chemical, in particular a fragrance or fragrance, is understood as meaning all organic substances which have a desired olfactory property and are substantially non-toxic. These include, among others, all fragrances or fragrances commonly used in detergent or cleaning compositions or in perfumery. It may be compounds of natural, semi-synthetic or synthetic origin. Preferred scents or fragrances can be assigned to the substance classes of hydrocarbons, aldehydes or esters. Fragrances also include natural extracts and / or essences which may contain complex mixtures of ingredients such as orange oil, lemon oil, rose extract, lavender, musk, patchouli, balsamic essence, sandalwood oil, pine oil and cedar oil. Non-limiting examples of synthetic and semi-synthetic fragrances or fragrances are: 7-acetyl-1,2,3,4,5,6,7,8-octahydro-1, 1, 6,7-tetramethylnaphthalene, a-ionone, β-ionone, γ-aminoethyl, α-isomethylionone, methyl cedryl ketone, methyl dihydrojasmonate, methyl-1, 6,10-trimethyl-2,5,9-cyclododecatriene-1-yl ketone, 7-acetyl-1, 1, 3,4,4,6-hexamethyl-tetralin, 4-acetyl-6-tert-butyl-1, 1-dimethylindane, hydroxyphenylbutanone, benzophenone, methyl-β-naphthyl ketone, 6-acetyl-1, 1, 2,3, 3,5-hexamethylindane, 5-acetyl-3-isopropyl-1,1,2,6-tetramethylindane, 1-dodecanal, 4- (4-hydroxy-4-methylpentyl) -3-cyclohexene-1-carboxaldehyde, 7- Hydroxy-3,7-dimethyloctanal, 10-undecene-1-al, iso-hexenyl-cyclohexylcarboxaldehyde, formyltricyclodecane, condensation products of hydroxycitronellal and methyl anthranilate, condensation products of hydroxycitronellal and indole, condensation products of phenylacetaldehyde and indole, 2-methyl-3- (para tert-butylphenyl) propionaldehyde, ethyl vanillin, heliotrope in, hexyl cinnamaldehyde, amyl cinnamic aldehyde, 2-methyl-2 - (- iso-propylphenyl) propionaldehyde, Cu Marine, γ-decalactone, cyclopentadecanolide, 16-hydroxy-9-hexadecenoic acid lactone, 1, 3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-Y-2- benzopyran, β-naphthol methyl ether, ambroxan, dodecahydro-3a, 6,6,9a-tetramethylnaphtho [2, Ib] furan, cedrol, 5- (2,2,3-trimethylcyclopent-3-enyl) -3- methylpentan-2-ol, 2-ethyl-4- (2,2,3-trimethyl-3-cyclopenten-1-yl) -2-buten-1-ol, caryophyllene alcohol, tricyclodecenylpropionate, tricyclodecenyl acetate, benzyl salicylate, cedryl acetate and tert-butyl cyclohexyl acetate.

Further examples of fragrances or rich substances which can be used in the microcapsules according to the invention are described, for example, in US Pat. No. 6,143,707, US Pat. No. 5,089,162, EP 1 360 270, DE 10 2008 030 662, paragraphs 0025 to 0036 and WO 2009/027957. A detailed description of the various most commonly used aroma chemicals which can also be used in the microcapsules of the present invention as a sparingly water-soluble or water-insoluble organic agent can be found in the book "Common Fragrance and Flavor Materials" by H. Surburg and J. Panten, 5. , completely. u. ext. Edition - February 2006, Wiley-VCH, Weinheim.

Particularly preferred are: hexyl cinnamic aldehyde, 2-methyl-3 - (- tert-butylphenyl) propionaldehyde, 7-acetyl-1,2,3,4,5,6,7,8-octahydro-1,1,6,7 tetramethylnaphthalene, benzyl salicylate, 7-acetyl-1,1,1,4,4,6-hexamethyl-tetralin, para-tert-butylcyclohexyl-acetate, methyl-dihydro-jasmonate, β-naphthol-methyl-ether, methyl-β naphthyl ketone, 2-methyl-2- (para-iso-propylphenyl) -propionaldehyde, 1, 3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta-Y 2-benzopyran, dodecahydro-3a, 6,6,9a-tetramethylnaphtho [2, Ib] furan, anisaldehyde, coumarin, cedrol, vanillin, cyclopentadecanolide, tricyclodecenyl acetate and tricyclodecenyl propionates.

Other fragrances include essential oils, resinoids and resins from a variety of sources such as Peru balsam, Olibanum resinoid, Styrax, Labdanum resin, nutmeg, cassia oil, benzoin resin, coriander and lavandin. Other suitable fragrances are: phenyl ethyl alcohol, terpineol, linalool, linalyl acetate, geraniol, nerol, 2- (1, 1 -dimethylethyl) - cyclohexanol acetate, benzyl acetate and eugenol.

The fragrances or fragrances can be used as pure substances or mixed with one another.

In principle, the sparingly water-soluble or water-insoluble organic active ingredient, preferably the Aromachemikalie, in particular the perfume or fragrance at 20 ° C, a liquid or a solid, wherein the solid itself in a suitable lipophilic solvent such as an oil, in dissolved form or may be present as a suspension. So z. B. when using solid at room fragrances or fragrances, the use of a liquid at room temperature hydrophobic material as a solution or dispersant advantage. The sparingly water-soluble or water-insoluble organic active substance used in the microcapsule according to the invention is preferably a liquid at 20 ° C. To increase the hydrophobicity of a fragrance or fragrance, this fragrance or fragrance, another hydrophobic material can be added.

Preferably, the sparingly water-soluble or water-insoluble organic active substance, in particular the fragrance or fragrance or the mixture of fragrances or fragrances, constitutes from 1 to 100% by mass, preferably from 20 to 100% by mass, of the hydrophobic core material. The hydrophobic material is liquid at temperatures below 100 ° C, preferably at temperatures below 60 ° C and most preferably at room temperature. In addition to the sparingly water-soluble and water-insoluble active ingredient, the core of the microcapsules according to the invention may also contain hydrophobic auxiliaries, such as oils or solvents, which are commonly used in the respective fields of application. The hydrophobic excipients that can be used as part of the core of the microcapsule of the invention include all types of oils, such as vegetable oils, animal oils, mineral oils, paraffins, chloroparaffins, fluorocarbons, and other synthetic oils.

Typical and non-limiting examples are sunflower oil, rapeseed oil, olive oil, peanut oil, soybean oil, kerosene, benzene, toluene, butane, pentane, hexane, cyclohexane, chloroform, carbon tetrachloride, chlorinated diphenyls and silicone oil. Hydrophobic high boiling point materials can also be used, e.g. Diethyl phthalate, di-butyl phthalate, diisohexyl phthalate, dioctyl phthalate, alkylnaphthalene, dodecylbenzene, terphenyl, partially hydrogenated terphenyls, ethylhexyl palmitates, capric / caprylic triglycerides, PPG-2 myristyl ether propionates, PPG-5 ceteth-20; Ci ₂ i5-alkyl benzoates, mineral oil (CAS: 8042-47-5), Cetearyl Ethylhexanoate, Dimethicone, polyisobutylenes (for example BASF. Glisopal ^®, Oppanol ^®). Typical oil components in cosmetics are, for example, paraffin oil, glyceryl stearate, isopropyl myristate, diisopropyl adipate, 2-ethylhexanoic acid cetylstearyl ester, hydrogenated polyisobutene, vaseline, caprylic acid / capric acid triglycerides, microcrystalline wax, lanolin and stearic acid. However, this list is exemplary and not exhaustive.

The microcapsules according to the invention have a shell directly around the core. This shell comprises at least one metal oxide and at least one water-soluble polymer. The metal oxide of the shell is usually a metal oxide insoluble in water (pH 7). The metal oxide of the shell is preferably such a metal oxide derived from a metal of which water-soluble, in particular readily soluble, salts of this metal are available in the oxidation state +11, +111 or + IV. The metal is particularly preferably present in these salts as a double or triple charged cation.

For the purposes of the present invention, readily soluble salts in water at 20 ° C. have a solubility of at least 10 g / l, preferably of at least 100 g / l, particularly preferably of at least 200 g / l.

The metal oxide of the shell is preferably an oxide of the metals zinc, cerium, zirconium, aluminum, magnesium, iron, manganese, nickel or cobalt. Particularly preferably, the metal oxide of the shell is zinc oxide.

The shell of the microcapsules according to the invention contains, in addition to the metal oxide, at least one water-soluble polymer. Examples of such water-soluble polymers are polyacrylates, polyaspartic acid, polyethers, polyvinylpyrrolidones and their corresponding copolymers.

The water-soluble polymer in the side chains preferably contains carboxy or carboxylate groups, for example in the case of polyacrylates or polyaspartic acid. Particularly preferred are polyacrylates.

The polyacrylates which are particularly preferred according to the invention are polymers based on at least one α, β-unsaturated carboxylic acid, for example acrylic acid, methacrylic acid, dimethacrylic acid, ethacrylic acid, maleic acid, citraconic acid, methylenemalonic acid, crotonic acid, isocrotonic acid, fumaric acid, mesaconic acid and itaconic acid. Preferably, polyacrylates based on acrylic acid, methacrylic acid, maleic acid or mixtures thereof are used.

In addition to the at least one α, β-unsaturated carboxylic acid, the polyacrylates may contain other comonomers which are polymerized into the polymer chain, for example, the esters, amides and nitriles of the above-mentioned carboxylic acids, eg. Methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyisobutyl acrylate, hydroxyisobutyl methacrylate, monomethyl maleate, dimethyl maleate, maleic monoethyl maleate, diethyl maleate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, Acrylamide, methacrylamide, N-dimethylacrylamide, N-tert-butylacrylamide, acrylonitrile, methacrylonitrile, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, diethyl laminoethyl methacrylate and the salts of the last-mentioned basic monomers with carboxylic acids or mineral acids and the quaternized products of the basic (meth) acrylates. Many of the present invention to be used polyacrylates are under the brand name Sokalan ^® (BASF SE) are commercially available. Very particular preference is given to a polyacrylate which is obtained from pure acrylic acid.

The molecular weight of the polyacrylates particularly preferred according to the invention is generally in the range of 800 to 250,000 g / mol, preferably in the range of 1,000 to 100,000 g / mol, particularly preferably in the range of 1,000 to 20,000 g / mol.

Another object of the present invention is also a process for producing microcapsules having a core-shell structure containing at least one low molecular weight, anionic surfactant, wherein each microcapsule inside a core containing at least one poorly water-soluble or water-insoluble organic active ingredient and directly around the core has a shell, the shell comprising at least one metal oxide and at least one water-soluble polymer, comprising the process steps

Preparation of an oil-in-water emulsion by emulsifying an oil phase which contains at least one sparingly water-soluble or water-insoluble organic active ingredient in a water phase containing at least one low molecular weight anionic surfactant and at least one water-soluble salt of a metal in the oxidation state + II, + III or + IV contains, using shear forces,

Washing the oil in water emulsion to remove water-free dissolved salt and anionic surfactant until the aqueous phase has a conductivity of less than 2.0 mS / cm,

Generation of solid metal oxide at the oil phase boundary from the water-soluble salt of the metal in the oxidation state + II, + III or + IV, which is bound in the region of the oil-water phase boundary, by adding an aqueous solution, the a strong base and a water-soluble polymer, to the emulsion washed in process step ii), and iv) if appropriate, purification and / or isolation of the core-shell microcapsules produced in process step iii). Preferred embodiments with regard to the sparingly water-soluble or water-insoluble active ingredient, with regard to the low molecular weight anionic surfactant with respect to the metal oxide, with regard to the water-soluble polymer, as well as preferred embodiments with regard to dimensions and mass fractions of the various constituents of the microcapsules having a core-shell structure, can be found in FIGS at the beginning given explanations.

In process step i), the preparation of an oil-in-water emulsion by emulsifying an oil phase containing at least one sparingly water-soluble or water-insoluble organic active ingredient in a water phase containing at least one low molecular weight, anionic surfactant and at least one water-soluble salt of a metal in the Oxidation state + II, + III or + IV, described using shear forces.

The methods for the preparation of emulsions using shear forces are known in principle to the person skilled in the art. Thus, for example, Fantaschale and pestle, fast stirrers, high pressure homogenizers, shakers, vibratory mixers, ultrasonic generators, emulsifying centrifuges, colloid mills or atomizers can be used to produce emulsions. The person skilled in the art selects in each case the suitable method and the appropriate emulsifying tool as a function of the desired result, for example the desired droplet size in the emulsion, and depending on the physicochemical properties of the chosen starting materials, for example their viscosity or their thermal stability.

In process step i), the proportion of the oil phase in the emulsion is preferably from 1 to 50% by weight, particularly preferably from 10 to 40% by weight, based on the total mass of the emulsion. The proportion by weight of the surfactants used in process step i), based on the mass of the oil phase, is preferably in the range from 0.5% to 20%, in particular in the range from 1% to 5%.

The water-soluble salt of a metal used in process step i) in the oxidation state + II, + III or + IV, in particular the oxidation state + II or + III is preferably a salt of said oxidation states which is readily soluble in water. Examples of such preferred salts are, for example, the halides, acetates or nitrates of the metals zinc, cerium, tin, aluminum, magnesium, iron, manganese, nickel or cobalt, in particular of zinc. Particular preference is given in step i) to use as the water-soluble salt zinc chloride, zinc nitrate or zinc acetate. In process step i), the concentration of the water-soluble salt of a metal used in the oxidation state + II, + III or + IV in the water phase is generally in the range from 0.05 to 1 mol / l, preferably in the range from 0.1 to 0.5 mol / l, more preferably in the range of 0.2 to 0.4 mol / l.

In method step i), the molar ratio between the low molecular weight anionic surfactant and the water-soluble salt of a metal in the oxidation state + II, + III or + IV is preferably in the range from 1:10 to 1: 1, preferably in the range from 1: 8 to 1: 3.

After preparation of the emulsion, this can be stirred for some time. It can be imagined that the formation of "multilayer metal ion shells" of the metal in the + II, + III or + IV oxidation state around the oil droplets externally surrounded with the anionic surfactant may take some time and 10 hours.

In process step ii), the oil prepared in process step i) is washed in water emulsion for the removal of water-free dissolved salt and anionic surfactant until the aqueous phase has a conductivity of less than 2.0 mS / cm.

Process step ii) can be realized by centrifuging, filtering, evaporating the solvents, re-suspending and dialysis processes. Particularly preferred in the inventive method as a filtration method, a cross-flow filtration is performed.

The emulsion is washed until the aqueous phase has a conductivity of less than 2.0 mS / cm, preferably a conductivity in the range of 0.1 to 0.5 mS / cm. The measurement of the conductivity is known to the person skilled in the art and can be carried out directly in the emulsion to be cleaned with a commercially available conductivity meter.

In process step iii), by adding an aqueous solution containing a strong base and a water-soluble polymer to the emulsion washed in process step ii) solid metal oxide at the oil phase boundary of the water-soluble salt of the metal in the oxidation state + II, + III or + IV, which is bound in the region of the oil-water phase boundary produced. The strong bases to be used according to the invention may generally be any substances capable of having a pH in aqueous solution of from about 8 to about 13, preferably about, depending on their concentration 9 to produce about 12.5. These may be, for example, metal oxides or hydroxides as well as ammonia or amines. Preference is given to using alkali metal hydroxides, such as sodium or potassium hydroxide, alkaline earth metal hydroxides, such as calcium hydroxide or ammonia. Particular preference is given to using sodium hydroxide, potassium hydroxide or ammonia, in particular sodium hydroxide, as the strong base.

The concentration of the strong base in the aqueous solution, which is added in process step iii) to the emulsion washed in process step ii), is generally selected such that in the aqueous solution a hydroxide ion concentration in the range of 0 , 1 to 2 mol / l, more preferably from 0.2 to 1 mol / l and in particular from 0.4 to 0.8 mol / l.

The molar amount of hydroxide ions in the aqueous solution is preferably chosen such that, at least theoretically, the metal ions of the metal present in the emulsion in the oxidation state + II, + III or + IV after the end of the addition of the aqueous solution are completely in the form of the corresponding hydroxides M (OH ) 2, M (OH) 3 or M (OH) ₄ could be present.

The concentration of the water-soluble polymer, in particular of the polyacrylates in the aqueous solution, which is added in process step iii) to the emulsion washed in process step ii) is generally in the range from 0.1 to 20 g / l, preferably in the range from 1 to 10 g / l, more preferably in the range of 1, 5 to 5 g / l. Of course, the water-soluble polymers used according to the invention must have a corresponding water solubility.

A preferred embodiment of the process according to the invention is characterized in that the precipitation of the metal oxide, metal hydroxide and / or the metal oxide hydroxide and production of the solid metal oxide takes place in the presence of a polyacrylate, which is obtained from pure acrylic acid. In a particularly OF PREFERRED th embodiment of the invention is Sokalan ^® PA 15 (from BASF SE), the sodium salt of a polyacrylic acid _(Mn: about 1200 g / mol; pH: 8; K-value according to ISO 1628 -1, 1% in distilled water: about 15).

The addition of the aqueous solution containing the strong base and the water-soluble polymer to the emulsion washed in process step ii) is usually carried out at a temperature in the range of 0 to 100 ° C, preferably 10 to 60 ° C, especially 30 to 45 ° C performed.

The addition of the aqueous solution, which contains the strong base and the water-soluble polymer, to the washed emulsion can, in principle, be carried out at any speed. Preferably, the addition is made evenly distributed in more than 30 minutes. Particularly preferred in step iii) the addition of the aqueous solution containing a strong base and a water-soluble polymer, evenly distributed over a period of 2 to 5 hours made. To the best of our knowledge, the water-soluble polymer serves to accelerate the dehydration of the primarily formed metal hydroxide to the metal oxide. The calcination process frequently used in the conversion of metal hydroxides into the corresponding metal oxides at temperatures above 100 ° C. can be dispensed with in the present process.

The suspension of microcapsules formed in process step iii) can be additionally stabilized by addition of further additives, such as nonionic, anionic or cationic polymers or surfactants. The microcapsules with core-shell structure produced in process step iii) can be further purified and / or isolated in a subsequent process step iv). The person skilled in the art is aware of appropriate purification and isolation processes, such as, for example, centrifuging, filtering, evaporation of the solvents, re-suspending and dialysis processes. Thus, by removing the solvents, in particular by removing the water, for example in a spray-drying process, a powder can be obtained from the aqueous suspension of the microcapsules.

The microcapsules according to the invention with a core-shell structure are suitable according to the encapsulated active ingredient as an additive to detergents and cleaners, fabric care products, cosmetics, pharmaceutical agents, crop protection compositions, plastics, animal feeds, foods or food supplements. Another object of the present invention is the use of the microcapsules with a core-shell structure described above or which were prepared by the method described above, as an additive to detergents and cleaners, fabric care products, cosmetics, pharmaceutical agents, pesticide preparations, plastics , Animal feed, food or nutritional supplements.

Another object of the present invention are powdered or liquid preparations comprising the above-described microcapsules having a core-shell structure or which have been prepared by the method described above. In addition to the microcapsules having a core-shell structure, the pulverulent or liquid preparations usually contain at least one of the customary additives and / or adjuvants which are suitable for the respective field of application, for example in the field of detergents and cleaners, fabric care products, cosmetics, Pharmaceutical agents, crop protection preparations, plastics, animal feed, food or dietary supplements are known.

Likewise provided by the present invention is the use of the above-described pulverulent or liquid preparations as an additive to detergents and cleaners, fabric care products, cosmetics, pharmaceutical agents, crop protection compositions, plastics, animal feeds, foods or food supplements.

Another object of the present invention are detergents and cleaners, fabric care products, cosmetics, pharmaceutical compositions, crop protection compositions, plastics, animal feed, food or dietary supplements containing the microcapsules according to the invention with a core-shell structure described above or according to the previously described methods were prepared.

The invention is illustrated by the following, but not limiting examples of the invention.

Examples

Example 1) Encapsulation of citronellyl nitrile (CAS Reg. No. 51566-62-2) with zinc oxide

20 g citronellylnitrile (BASF SE) were dissolved at room temperature (20 ° C) in a mixture of 7.5 g of paraffin oil and 2.5 g of glycerol monooleate (Mazol PGO ^® 31 K of BASF Corporation). 4 g of polyoxyethylene (20) sorbitan monolaurate (polysorbate 20, commercially available under Tween ^® 20) were alkylphenol ether sulfate and 4 g (Lutensit ^® A-ES from BASF SE) in 150 g of a 0.5 molar aqueous solution of zinc chloride solved. The oil phase was homogenized with the water phase with the aid of an ultrasonic rod (sonotrode 14 mm) for 3 minutes. The emulsion was stirred for 2 hours at room temperature to complete the formation of the zinc ion hydration vials around the oil droplets. Free salt and excess surfactant were washed out of the emulsion by cross-flow filtration until an emulsion conductivity value of 0.5 mS / cm was reached. (BASF SE, Sokalan ^® PA 15) in a concentration of 5 g / l 75 ml of a 1 molar aqueous solution of NaOH, the polyacrylic acid sodium salt, was slowly added (0.5 ml / min) to the washed emulsion, to start the formation of zinc oxide on the surface of the oil droplets. After completion of the addition of NaOH and Polyacrylic acid-sodium salt-containing solution, the suspension formed at 40 ° C for 5 h was further stirred with a magnetic stirrer to age the zinc oxide shells.

The particle size distribution of the microcapsules formed was determined by means of light scattering in accordance with ISO 13320-1 (Microtrac S3500 Bluewave from Microtrac):

The theoretical loading of the microcapsules with citronellylnitrile is about 45% by weight, based on the mass of the microcapsules.

The actual loading of the microcapsules was determined by thermogravimetry (TGA). The weight loss of a dried at 300 ° C sample compared to the spray-dried at 130 ° C starting sample is about 30%. This means that the loading of the microcapsules is at least 30% by weight, based on the mass of the microcapsules.

Example 2) Encapsulation of linalyl acetate (CAS Reg. No. 1 15-95-7) with zinc oxide

0.6 g of polyoxyethylene (20) sorbitan monolaurate (polysorbate 20, commercially available under Tween ^® 20) and 0.6 g of alkylphenol ether sulfate (Lutensit ^® A-ES from BASF SE) were dissolved in 30 g of a 0.5 molar, dissolved aqueous solution of zinc chloride. As the oil phase, 6 g of linalyl acetate (BASF SE) were homogenized together with the water phase with the aid of an ultrasonic rod (sonotrode 6 mm) for 3 minutes. The emulsion was stirred for 2 hours at 40 ° C to complete the formation of the zinc ion hydration shells around the oil droplets. Free salt and excess surfactant were washed out of the emulsion by means of cross-flow filtration until a value for the conductivity of the emulsion of 0.5 mS / cm was reached. 30 ml of a 1 molar aqueous solution of NaOH, the polyacrylic acid sodium salt (Sokalan ^® PA 15 of the company. BASF SE) in a concentration of 5 g / l, at a flow rate of 0.5 ml / min to the washed emulsion added to start the formation of zinc oxide on the surface of the oil droplets. After completion of the addition of the NaOH and polyacrylic acid sodium salt-containing solution, the resulting suspension was further stirred at 40 ° C for 5 hours with a magnetic stirrer to age the zinc oxide dishes.

d50 = 0.5 \ m. Example 3) Encapsulation of 2-methyl-3- (4-tert-butylphenyl) -propanal (Lysmeral ^® Extra by BASF SE) (CAS Reg 80-54-6) with zinc oxide

0.6 g of polyoxyethylene (20) sorbitan monolaurate (polysorbate 20, commercially available under Tween ^® 20) and 0.6 g of alkylphenol ether sulfate (Lutensit ^® A-ES from BASF SE) were dissolved in 30 g of a 0.5 molar, dissolved aqueous solution of zinc chloride. As the oil phase 6 g of 2-methyl-3- (4-tert-butylphenyl) -propanal (Lysmeral ^® Extra by BASF SE), together with the water phase with the aid of an ultrasonic rod (sonotrode de 14 mm) were homogenized for 3 minutes. The emulsion was stirred for 2 hours at 40 ° C to complete the formation of the zinc ion hydrate shells around the oil droplets. Free salt and excess surfactant were washed out of the emulsion by cross-flow filtration until an emulsion conductivity value of 0.5 mS / cm was reached. 30 ml of a 1 molar aqueous solution of NaOH containing polyaspartic acid at a concentration of 5 g / l was added to the washed emulsion at a flow rate of 0.5 ml / min to prevent the formation of zinc oxide on the surface of the To start oil droplets. After completion of the addition of the NaOH and polyaspartic acid-containing solution, the resulting suspension was further stirred at 40 ° C for 8 hours with a magnetic stirrer to age the zinc oxide shells.

d50 = 0.8 \ m.

Claims

claims

Microcapsules having a core-shell structure containing at least one low molecular weight anionic surfactant, wherein each microcapsule inside comprises a core containing at least one sparingly water-soluble or water-insoluble organic agent and having a shell directly around the core, the shell being at least a metal oxide and at least one water-soluble polymer.

Microcapsules according to claim 1, wherein the metal oxide of the shell is zinc oxide.

3. Microcapsules according to claim 1 or 2, wherein the sparingly water-soluble or water-insoluble organic active substance is an aroma gas mixture.

4. Microcapsules according to any one of claims 1 to 3, wherein the microcapsules in addition to the low molecular weight, anionic surfactant further comprise at least one nonionic surfactant.

5. Microcapsules according to any one of claims 1 to 4, wherein the low molecular weight, anionic surfactant is a fatty alcohol sulfate or an alkylphenol ether sulfate.

6. microcapsules according to any one of claims 1 to 5, wherein the water-soluble polymer in the side chains carboxy or carboxylate groups.

7. Microcapsules according to any one of claims 1 to 6, wherein the microcapsules have an average particle size of less than 2 μηη.

8. microcapsules according to any one of claims 1 to 7, wherein the core at 20 ° C is a liquid.

A process for producing microcapsules having a core-shell structure containing at least one low molecular weight anionic surfactant, wherein each microcapsule internally has a core containing at least one sparingly water-soluble or water-insoluble organic agent and a shell directly around the core, wherein the shell comprises at least one metal oxide and at least one water-soluble polymer, comprising the process steps i) preparation of an oil-in-water emulsion by emulsifying an oil phase containing at least one sparingly water-soluble or water-insoluble organic active substance in a water phase containing at least one low molecular weight , anionic surfactant and at least one water-soluble salt of a metal in the + II, + III or + IV oxidation state using shear forces, ii) washing the oil in water emulsion to remove water-free dissolved salt and anionic surfactant until the w iii) production of solid metal oxide at the oil phase boundary from the water-soluble salt of the metal in the oxidation state + II, + III or + IV, which is within the range of Oil-water phase boundary is bound, by adding an aqueous solution containing a strong base and a water-soluble polymer to the emulsion washed in step ii), and iv) optionally cleaning and / or isolation of the microcapsules produced in step iii) Core-shell construction.

The method of claim 9, wherein in step i) as a water-soluble salt zinc chloride, zinc nitrate or zinc acetate is used.

The method of claim 10 or 1 1, wherein in step iii) the addition of the aqueous solution containing a strong base and a water-soluble polymer, evenly distributed over a period of 2 to 5 hours is made.

Use of the microcapsules having a core-shell structure according to one of claims 1 to 8 or prepared by a method according to one of the Claims 9 to 1 1 as an additive to detergents and cleaners, fabric care products, cosmetics, pharmaceutical agents, crop protection preparations, plastics, animal feed, food or food supplements.

Powdery or liquid preparations containing microcapsules having a core-shell structure according to one of claims 1 to 8 or prepared by a process according to one of claims 9 to 11.

Use of the pulverulent or liquid preparations according to Claim 13 as an additive to detergents and cleaners, fabric care preparations, cosmetics, pharmaceutical agents, crop protection preparations, plastics, animal feeds, foods or food supplements.

Detergents and cleaners, fabric care preparations, cosmetics, pharmaceutical preparations, crop protection preparations, plastics, animal feed, foodstuffs or food supplements, containing the microcapsules having a core-shell structure according to one of claims 1 to 8 or prepared by a process according to one of claims 9 to 1 1 .