DE102007055813A1 - Micro-capsule, useful e.g. in thermal coating processes, comprises a capsule core and a capsule wall exhibiting two different monomers comprising e.g. (meth)acrylic acid, bi or polyfunctional monomers and other monomers - Google Patents

Abstract

Micro-capsule (A) comprises a capsule core and a capsule wall exhibiting: at least two different monomers (30-100 wt.%) (monomers I) comprising 1-24C alkylester of acrylic acid and/or methacrylic acid, acrylic acid, methacrylic acid and maleic acid; one or more bi or polyfunctional monomers (0-30 wt.%) (monomers II), which is in-soluble or poorly soluble in water; and one or more other monomers (0-40 wt.%) (monomers III), where the monomer I comprises 10-90 wt.% of a monomer Ia, whose homopolymer exhibits a glass transition temperature of = 60[deg] C. An independent claim is included for process for preparing (A) comprising heating an oil-in water emulsion, in which the monomers, a radical initiator, a colloidal protector and the lipophilic substances are present in a dispersion phase.

Description

The The present invention relates to thermally destructible microcapsules, a process for their preparation and their use for thermal release of lipophilic substances.

microcapsules are in various embodiments are known and depending on the tightness of the capsule wall to very different Used for purposes. For example, they serve to protect core materials, the first released by targeted mechanical destruction of the capsule wall be, for example, from dyes for carbonless paper or of encapsulated perfumes. Known in such applications capsule wall materials on gelatin, polyurethane resin, melamine-formaldehyde resin as well as polyacrylate base. Other requirements apply to wall materials for herbal or pharmaceutically active substances as core materials which it is on a permeability the capsule wall arrives, the controlled release and the targeted transport of drugs allows. Here you know next to the capsules produced by chemical processes also mechanical-physical manufacturing process.

Microcapsules with wall material based on a highly crosslinked methacrylic acid ester polymer are known from EP-A 1 029 018 . DE-A 101 39 171 . WO 2005/116559 as well as the older one European application no. 06117092.4 known. They all relate to microencapsulated latent heat storage materials in various fields of application. That's how it teaches EP-A 1 029 018 its use in binders such as concrete or gypsum, the DE-A 101 39 171 the use of microencapsulated latent heat storage materials in plasterboard and the WO 2005/116559 their use in chipboard. The older one European application no. 06117092.4 teaches polyelectrolyte-modified microcapsules with average particle sizes of 4.7 microns and larger that exhibit improved chemical cleaning resistance in the textile industry. All of the microcapsules described in these documents have in common that they should have a high density, both in thermal and chemical treatment or under pressure.

at the coating with polyurethane dispersions are filmable Polymers melted on a surface under high temperatures. An important requirement is that the coating itself subsequently does not feel sticky. In general, stickiness can be prevented by post-crosslinking, However, the process is technically complex. Therefore, there was the Need for a system that already has a postcrosslinker in containing the polyurethane dispersion and only during it release the film.

Of the The present invention was therefore based on microcapsules, which selectively release the core material under thermal treatment.

Accordingly, microcapsules have been found comprising a capsule core and a capsule wall, wherein the capsule wall is constructed from From 30 to 100% by weight at least two mutually different monomers (monomers I) from the group comprising C ₁ -C ₂₄ -alkyl esters of acrylic and / or methacrylic acid, acrylic acid, methacrylic acid and maleic acid, 0 to 30% by weight one or more bi- or polyfunctional monomers (monomers II) which is insoluble or sparingly soluble in water, and 0 to 40% by weight one or more other monomers (monomers III), in each case based on the total weight of the monomers, wherein the monomers I comprise from 10 to 90% by weight, based on the total amount of the monomers I, of at least one monomer Ia whose homopolymer has a glass transition temperature ≦ 60 ° C., a process for their preparation and their use for the thermal release of lipophilic substances.

The microcapsules according to the invention comprise a capsule core and a capsule wall of polymer. The capsule core consists predominantly, to more than 95% by weight, of lipophilic substance. The capsule core can dependent be both solid and liquid from the temperature.

Depending on the preparation process and the selected protective colloid, this may also be part of the microcapsules. Thus, up to 10 wt .-% based on the total weight of the micro capsules be protective colloid. According to this embodiment, the microcapsules on the surface of the polymer have the protective colloid.

The mean particle size of the capsules (Z-means by light scattering) is 0.5 to 50 microns, preferably 0.5 to 30 μm. The weight ratio from capsule core to capsule wall is generally from 50:50 to 95: 5th Preferred is a core / wall ratio from 70:30 to 93: 7.

The polymers of the capsule wall generally contain at least 30 wt .-%, preferably at least 40 wt .-%, in a particularly preferred form at least 50 wt .-%, in particular at least 60 wt .-%, most preferably at least 70 wt. -% and up to 100 wt .-% of at least two mutually different monomers I from the group comprising C ₁ -C ₂₄ alkyl esters of acrylic and / or Me thacrylsäure, acrylic acid, methacrylic acid and / or maleic acid copolymerized, based on the total weight of monomers. These monomers I comprise 10 to 90 wt .-%, preferably 10 to 70 wt .-%, in particular 15 to 50 wt .-%, based on the total amount of the monomers I, at least one monomer Ia which is capable of having a homopolymer a glass transition temperature (T _g ) of ≤ 60 ° C, preferably ≤ 50 ° C, more preferably ≤ 40 ° C to form.

The glass transition temperature (T _g ) of a Polmer is defined in Encyclopedia of Chemical Technology, Volume 19, 4th Edition, page 891 , as the temperature below which the Brownian molecular movements of longer chain segments (20-50 chain atoms) of the polymers are frozen. A polymer exhibits neither flow behavior nor rubber elasticity below its glass transition temperature. The glass transition temperature is determined by DSC according to DIN 53765: 1994-03.

In addition, the Polymers of the capsule wall generally up to 30 wt .-%, preferably at most 25% by weight and in a particularly preferred form at most 20% by weight of a or polyfunctional monomer as monomers II, which is in water not soluble or sparingly soluble is included in copolymerized form.

Besides can the polymers up to 40 wt .-%, preferably up to 30 wt .-%, in particular contain up to 20 wt .-% of other monomers III in copolymerized form.

Preferably the capsule wall is composed only of monomers of group I and III. Particularly preferably, the capsule walls are substantially, preferably exclusively composed of monomers of group I.

Suitable monomers I are the C ₁ -C ₂₄ -alkyl esters of acrylic and / or methacrylic acid. Also suitable are the unsaturated C ₃ - and C ₄ -carboxylic acids such as acrylic acid, methacrylic acid and maleic acid. Examples which may be mentioned are methyl, ethyl, n-propyl, iso-propyl, n-butyl, isobutyl, sec-butyl and tert-butyl acrylate and also methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and tert-butyl methacrylate.

Suitable monomers Ia whose homopolymer has a glass transition temperature (T _g ) of ≦ 60 ° C. are, for example, the C ₁ -C ₂₄ -alkyl esters of acrylic acid and butyl methacrylate. Examples which may be mentioned are methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, t-butyl acrylate, n-pentyl acrylate, 2-methylbutyl acrylate, 3-methylbutyl acrylate, hexyl acrylate, ethylhexyl acrylate and propylheptyl acrylate. Preference is given to n-butyl acrylate.

suitable Monomers II are bi- or polyfunctional monomers which are dissolved in water not soluble or sparingly soluble but have good to limited solubility in the lipophilic Have substance. Under low solubility is a solubility less than 60 g / l at 20 ° C to understand. Under bi- or polyfunctional monomers understands compounds which contain at least two nonconjugated ethylenic Have double bonds. In particular, divinyl and polyvinyl monomers are used which is a cross-linking of the capsule wall during the Cause polymerization.

Geignete Divinyl monomers are divinylbenzene, trivinylbenzene and divinylcyclohexane and trivinylcyclohexane. Preferred divinyl monomers are the diesters of diols with acrylic acid or methacrylic acid, also the diallyl and divinyl ethers of these diols. exemplary Ethandioldiacrylat, ethylene glycol dimethacrylate, 1,3-Butylenglykoldimethacrylat, Methallylmethacrylamid, allyl acrylate and allyl methacrylate called. Particularly preferred are propanediol, butanediol, pentanediol and Hexanediol diacrylate and the corresponding methacrylates.

preferred Polyvinyl monomers are the polyesters of polyols with acrylic acid and / or methacrylic acid, also the polyallyl and polyvinyl ethers of these polyols. Prefers are trimethylolpropane triacrylate and methacrylate, pentaerythritol triallyl ether, Pentaerythritol tetraallyl ether, pentaerythritol triacrylate and pentaerythritol tetraacrylate as well as their technical mixtures.

When Other monomers III come from the monomers I different monoethylenically unsaturated Monomers are suitable, preference is given to monomers IIIa, such as vinyl acetate, Vinyl propionate and vinylpyridine.

Especially preferred are the water-soluble Monomers IIIb, z. Acrylonitrile, methacrylamide, acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, N-vinylpyrrolidone, 2-hydroxyethyl acrylate and methacrylate and acrylamido-2-methylpropanesulfonic acid. Besides in particular N-methylolacrylamide, N-methylolmethacrylamide, dimethylaminoethylmethacrylate and diethylaminoethyl methacrylate.

The glass transition temperature of the capsule wall may be -60 to 150 ° C, preferably -40 to 100 ° C, in a particular embodiment 0 to 100 ° C, especially 0 to 80 ° C and most preferably 40 to 80 ° C; the above glass transition temperature is that described by Fox (see also Handbook of Polymer Science and Technology, 1989 or TG Fox, Bull. Am. Phys. Soc. (ser II) 1, 123, 1956 ) calculated from the weight fraction of the monomers and the glass transition temperature of the homopolymers glass transition temperature in the calculation monomers with two or more than two copolymerizable ethylenically unsaturated groups are not taken into account, ie the sum of all other monomers corresponds to 100 wt .-%.

Suitable core materials for the microcapsules are liquid or solid substances which are insoluble or substantially insoluble in water and are referred to below as lipophilic substances. The lipophilic substance can be both a single substance and a mixture, in the form of a solution, suspension or emulsion. Lipophilic substances are selected, for example, from the group comprising aliphatic and aromatic hydrocarbon compounds, saturated or unsaturated C ₆ -C ₃₀ -fatty acids, fatty alcohols, C ₆ -C ₃₀ fatty amines, fatty acid esters, natural and synthetic waxes, halogenated hydrocarbons, silicone oils, adhesives, flavoring agents, Fragrances, active ingredients, dyes, color formers, pigments and crosslinkers.

• a) aliphatische Kohlenwasserstoffverbindungen wie gesättigte oder ungesättigte C₁₀-C₄₀-Kohlenwasserstoffe, die verzweigt oder bevorzugt linear sind, z. B. wie n-Tetradecan, n-Pentadecan, n-Hexadecan, n-Heptadecan, n-Octadecan, n-Nonadecan, n-Eicosan, n-Heneicosan, n-Docosan, n-Tricosan, n-Tetracosan, n-Pentacosan, n-Hexacosan, n-Heptacosan, n-Octacosan sowie cyclische Kohlenwasserstoffe, z. B. Cyclohexan, Cyclooctan, Cyclodecan;
• b) aromatische Kohlenwasserstoffverbindungen wie Benzol, Naphthalin, Biphenyl, o- oder m-Terphenyl, C₁-C₄₀-alkylsubstituierte aromatische Kohlenwasserstoffe wie Dodecylbenzol, Tetradecylbenzol, Hexadecylbenzol, Hexylnaphthalin oder Decylnaphthalin;
• c) gesättigte oder ungesättigte C₆-C₃₀-Fettsäuren wie Laurin-, Stearin-, Öl- oder Behensäure, bevorzugt eutektische Gemische aus Decansäure mit z. B. Myristin-, Palmitin- oder Laurinsäure;
• d) Fettalkohole wie Lauryl-, Stearyl-, Oleyl-, Myristyl-, Cetylalkohol, Gemische wie Kokosfettalkohol sowie die sogenannten Oxoalkohole, die man durch Hydroformylierung von α-Olefinen und weiteren Umsetzungen erhält;
• e) C₆-C₃₀-Fettamine, wie Decylamin, Dodecylamin, Tetradecylamin oder Hexadecylamin;
• f) Ester wie C₁-C₁₀-Alkylester von Fettsäuren wie Propylpalmitat, Methylstearat oder Methylpalmitat sowie bevorzugt ihre eutektischen Gemische oder Methylcinnamat;
• g) natürliche und synthetische Wachse wie Montansäurewachse, Montanesterwachse, Carnaubawachs, Polyethylenwachs, oxidierte Wachse, Polyvinylether wachs, Ethylenvinylacetatwachs oder Hartwachse nach Fischer-Tropsch-Verfahren;
• h) halogenierte Kohlenwasserstoffe wie Chlorparaffin, Bromoctadecan, Brompentadecan, Bromnonadecan, Bromeicosan, Bromdocosan.
• i) natürliche Öle wie Erdnussöl, Sojaöl,
• k) Siliconöle beispielsweise mit M_w 1000-150000, Dichte 0,94-0,97 u. Viskositäten zwischen 10 u. 1 000 000 mPa·s.
• l) Klebstoffe, Aromastoffe, Duftstoffe und Wirkstoffe wie Pflanzenschutzmittel, gegebenenfalls als Lösung oder Suspension in den obengenannten lipophilen Substanzen der Gruppen a) bis i)
• m) außerdem Lösungen oder Suspensionen von Farbstoffen, Farbbildnern und anorganische und organische Pigmenten in den obengenannten lipophilen Substanzen der Gruppen a) bis i).
• n) Vernetzer, wie Carbodiimide oder andere reaktive, mehrfunktionelle Verbindungen wie Epoxide, Amine etc..

Examples include:

• a) aliphatic hydrocarbon compounds such as saturated or unsaturated C ₁₀ -C ₄₀ hydrocarbons which are branched or preferably linear, for. Such as n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, n-eicosane, n-heneicosane, n-docosane, n-tricosane, n-tetracosane, n-pentacosan , n-hexacosane, n-heptacosane, n-octacosane and cyclic hydrocarbons, e.g. Cyclohexane, cyclooctane, cyclodecane;
• b) aromatic hydrocarbon compounds such as benzene, naphthalene, biphenyl, o- or m-terphenyl, C ₁ -C ₄₀ -alkyl-substituted aromatic hydrocarbons such as dodecylbenzene, tetradecylbenzene, hexadecylbenzene, hexylnaphthalene or decylnaphthalene;
• c) saturated or unsaturated C ₆ -C ₃₀ fatty acids such as lauric, stearic, oleic or behenic acid, preferably eutectic mixtures of decanoic acid with z. Myristic, palmitic or lauric acid;
• d) fatty alcohols such as lauryl, stearyl, oleyl, myristyl, cetyl alcohol, mixtures such as coconut fatty alcohol and the so-called oxo alcohols, which are obtained by hydroformylation of α-olefins and other reactions;
• e) C ₆ -C ₃₀ fatty amines, such as decylamine, dodecylamine, tetradecylamine or hexadecylamine;
• f) esters, such as C ₁ -C ₁₀ -alkyl esters of fatty acids, such as propyl palmitate, methyl stearate or methyl palmitate, and preferably their eutectic mixtures or methyl cinnamate;
• g) natural and synthetic waxes such as montanic acid waxes, montan ester waxes, carnauba wax, polyethylene wax, oxidized waxes, polyvinyl ether wax, ethylene vinyl acetate wax or Fischer-Tropsch wax waxes;
• h) halogenated hydrocarbons such as chlorinated paraffin, bromoctadecane, bromopentadecane, bromononadecane, bromeicosane, bromodocosane.
• i) natural oils such as peanut oil, soybean oil,
• k) silicone oils, for example with M _w 1000-150000, density 0.94-0.97 u. Viscosities between 10 u. 1 000 000 mPa · s.
• (l) Adhesives, flavorings, fragrances and active substances, such as plant protection products, optionally as a solution or suspension in the abovementioned lipophilic substances of groups (a) to (i)
• m) also solutions or suspensions of dyes, color formers and inorganic and organic pigments in the abovementioned lipophilic substances of groups a) to i).
• n) crosslinkers, such as carbodiimides or other reactive, polyfunctional compounds such as epoxides, amines, etc.

The microcapsules according to the invention can be prepared by a so-called in situ polymerization. The principle of microcapsule formation is based on preparing a stable oil-in-water emulsion from the monomers, a radical initiator, a protective colloid and the lipophilic substance to be encapsulated. Subsequently, the polymerization of the monomers is initiated by heating and optionally controlled by further increase in temperature, wherein the resulting polymers form the capsule wall, which encloses the lipophilic substance. This general principle is used for example in the DE-A 101 39 171 described in the content of which reference is expressly made.

In usually the microcapsules become in the presence of at least one prepared organic or inorganic protective colloid. Either Organic as well as inorganic protective colloids can be ionic or can be neutral. Protective colloids can be used individually as well also in mixtures of several same or differently charged Protective colloids are used.

organic Protective colloids are preferably water-soluble polymers which reduce the surface tension of the Lower water from 73 mN / m maximum to 45 to 70 mN / m and thus ensure the formation of closed capsule walls as well as microcapsules with preferred particle sizes in the range from 0.5 to 50 μm, preferably 0.5 to 30 μm in particular 0.5 to 10 μm, form.

organic neutral protective colloids are, for example, cellulose derivatives such as Hydroxyethylcellulose, methylhydroxyethylcellulose, methylcellulose and carboxymethylcellulose, polyvinylpyrrolidone, copolymers of Vinylpyrrolidone, gelatin, gum arabic, xanthan, casein, polyethylene glycols, Polyvinyl alcohol and partially hydrolyzed polyvinyl acetates and Methylhydroxypropylcellulose. Preferred organic neutral protective colloids are polyvinyl alcohol and partially hydrolyzed polyvinyl acetates and methylhydroxypropylcellulose.

in the general polyvinyl alcohol or partially hydrolyzed polyvinyl acetate in a total amount of at least 3% by weight, preferably 6 used to 8 wt .-%, based on the microcapsules (without protective colloid). It is possible other protective colloids mentioned above in addition to the preferred amounts Polyvinyl alcohol or partially hydrolyzed polyvinyl acetate. The microcapsules are preferred only with polyvinyl alcohol and / or partially hydrolyzed polyvinyl acetate and prepared without the addition of further protective colloids.

Polyvinyl alcohol is obtainable by polymerizing vinyl acetate, optionally in the presence of comonomers, and hydrolysis of the polyvinyl acetate with elimination of the acetyl groups to form hydroxyl groups. The degree of hydrolysis of the polymers may be, for example, 1 to 100%, and is preferably in the range of 50 to 100%, more preferably 65 to 95%. For the purposes of this application, partially hydrolyzed polyvinyl acetates are to be understood as meaning a degree of hydrolysis of <50% and polyvinyl alcohol of ≥ 50 to 100%. The preparation of homo- and copolymers of vinyl acetate and the hydrolysis of these polymers to form polymers containing vinyl alcohol units is well known. Vinyl alcohol units-containing polymers are sold, for example as Mowiol ^® grades from Kuraray Specialties Europe (KSE).

Prefers are polyvinyl alcohols or partially hydrolyzed polyvinyl acetates, the viscosity of a 4 wt .-% aqueous solution at 20 ° C according to DIN 53015 has a value in the range of 3 to 56 mPa · s, preferably a value of 14 to 45 mPa · s, in particular from 22 to 41 mPa · s. Preference is given to polyvinyl alcohols having a degree of hydrolysis of ≥ 65%, preferably ≥ 70%, in particular ≥ 75%.

organic anionic protective colloids are sodium alginate, polymethacrylic acid and their copolymers, the copolymers of sulfoethyl acrylate and methacrylate, sulfopropyl acrylate and methacrylate, N- (sulfoethyl) -maleimide, of 2-acrylamido-2-alkylsulfonic acids, styrenesulfonic acid as well the vinylsulfonic acid. Preferred organic anionic protective colloids are naphthalenesulfonic acid and Naphthalene sulfonic acid-formaldehyde condensates and especially polyacrylic acids and phenolsulfonic acid-formaldehyde condensates.

As inorganic protective colloids, so-called Pickering systems are mentioned, which allow stabilization by very fine solid particles and are insoluble in water but dispersible or insoluble and not dispersible in water but wettable by the lipophilic substance. The mode of action and you Use is in the EP-A 1 029 018 as well as the EP-A 1 321 182 whose contents are expressly referred to.

One Pickering system can be made of the solid particles alone or additionally consist of excipients that control the dispersibility of the particles in water or the wettability of the particles by the lipophilic phase improve.

The inorganic solid particles can Metal salts, such as salts, oxides and hydroxides of calcium, magnesium, Iron, zinc, nickel, titanium, aluminum, silicon, barium and manganese. These include magnesium hydroxide, magnesium carbonate, magnesium oxide, Calcium oxalate, calcium carbonate, barium carbonate, barium sulfate, titanium dioxide, Alumina, aluminum hydroxide and zinc sulfide. Silicates, bentonite, Hydroxyapatite and hydrotalcites are also mentioned. Especially fumed silica, magnesium pyrophosphate are preferred and tricalcium phosphate.

The Pickering systems can both be added to the water phase first, as well as added to the stirred oil-in-water emulsion. Some fine, solid particles are made by precipitation, as in the EP-A 1 029 018 , as well as the EP-A 1 321 182 described.

The highly dispersed silicic acids can as fine, solid particles are dispersed in water. But it is also possible, so-called colloidal dispersions of silica in water. Such colloidal dispersions are alkaline, aqueous mixtures of silica. in the alkaline pH range, the particles are swollen and in water stable. For it is a use of these dispersions as a Pickering system advantageous when the pH of the oil-in-water emulsion with a Acid on pH 2 to 7 is set.

in the in general, the protective colloids are used in amounts of from 0.1 to 15% by weight, preferably used from 0.5 to 10 wt .-%, based on the water phase. For inorganic Protective colloids are preferably amounts of from 0.5 to 15% by weight, based on the water phase selected. Organic protective colloids are preferred in amounts of 0.1 to 10 wt .-% used, based on the water phase of the emulsion.

According to one embodiment are inorganic protective colloids and their mixtures with organic Protective colloids preferred.

According to one another embodiment Organic neutral protective colloids are preferred.

Prefers are OH-protecting protective colloids such as polyvinyl alcohols and partially hydrolyzed polyvinyl acetates.

Further Is it possible for costabilization surfactants, preferably to add nonionic surfactants. Suitable surfactants are the "Handbook of Industrial Surfactants " whose contents are expressly referred to. The surfactants can in an amount of 0.01 to 10 wt .-% based on the water phase the emulsion can be used.

When Radical starter for the free-radical polymerization reaction, the usual Peroxo and azo compounds, expediently in amounts of 0.2 to 5 wt .-%, based on the weight of the monomers used.

ever by state of aggregation of the radical initiator and its solubility behavior it may as such, but preferably as a solution, emulsion or suspension supplied become, whereby in particular small quantities of radical starter more precise let it dose.

When preferred radical initiators are tert-butyl peroxoneodecanoate, tert-amyl peroxypivalate, Dilauroyl peroxide, tert-amyl peroxy-2-ethylhexanoate, 2,2'-azobis (2,4-dimethyl) valeronitrile, 2,2'-azobis- (2-methylbutyronitrile), Dibenzoyl peroxide, tert-butyl per-2-ethylhexanoate, di-tert-butyl peroxide, tert-butyl hydroperoxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane and cumene hydroperoxide to call.

Especially preferred free radical initiators are di (3,5,5-trimethylhexanoyl) peroxide, 4,4'-azobisisobutyronitrile, tert-butyl perpivalate and dimethyl 2,2-azobisisobutyrate. These wise a half life of 10 hours in a temperature range of 30 to 100 ° C on.

Furthermore, it is possible for the polymerization known in the art controllers in conventional amounts such as tert-dodecyl mercaptan or Ethylhexylthioglycolat.

Preferably you choose the dispersing conditions for the preparation of the stable oil-in-water emulsion in a conventional manner so that the oil droplets the size of the desired Have microcapsules.

In usually leads the polymerization at 40 to 150 ° C, preferably at 60 to 120 ° C by. Naturally should the dispersion and polymerization temperature above the Melting temperature of the lipophilic substances are.

In usually leads the polymerization at 20 to 100 ° C, preferably at 40 to 95 ° C by. Dependent from the desired lipophilic substance is the oil-in-water emulsion at one Temperature at which the core material is liquid / oily. Accordingly, a radical starter whose decomposition temperature must be selected above this temperature and the polymerization must also 2 to 50 ° C be carried out above this temperature, so that if necessary Radical starter chooses, their decomposition temperature above the melting point of the lipophilic Substance lies.

A common Process variant for Lipophilic substances with a melting point up to about 60 ° C is one Reaction temperature starting at 60 ° C, during the course of the reaction at 85 ° C elevated becomes. Advantageous radical starters have a 10-hour half-life in the range of 45 to 65 ° C such as t-butyl perpivalate.

To a further process variant for lipophilic substances with a melting point above 60 ° C. you choose a temperature program, which at correspondingly higher reaction temperatures starts. For Initial temperatures around 85 ° C be radical starters with a 10-hour half-life in the range of 70 to 90 ° C preferred as t-butylper-2-ethylhexanoate.

Conveniently, the polymerization is carried out at atmospheric pressure, but can even at reduced or slightly elevated pressure z. B. at a Polymerization temperature above 100 ° C, work, ie in the area from 0.5 to 5 bar.

The Reaction times of the polymerization are normally 1 to 10 hours, usually 2 to 5 hours.

A inventive variant of the method using polyvinyl alcohol and / or partially hydrolyzed polyvinyl acetate allows an advantageous procedure, according to the directly at elevated temperature is dispersed and polymerized.

Following the actual polymerization reaction at a conversion of 90 to 99% by weight, it is generally advantageous to make the aqueous microcapsule dispersions substantially free of odor carriers, such as residual monomers and other volatile organic constituents. This can be achieved physically in a manner known per se by distillative removal (in particular via steam distillation) or by stripping with an inert gas. Furthermore, it can be chemically done, as in the WO 99/24525 described, advantageously by redox-initiated polymerization, as in DE-A 44 35 423 . DE-A 44 19 518 and DE-A 44 35 422 described. It is possible in this way to produce microcapsules having an average particle size in the range from 0.5 to 100 .mu.m, it being possible to adjust the particle size in a manner known per se by means of the shearing force, the stirring rate, the protective colloid and its concentration. Preference is given to microcapsules having an average particle size in the range from 0.5 to 50 .mu.m, preferably 0.5 to 30 .mu.m (Z agent by means of light scattering).

The microcapsules according to the invention preferably directly as aqueous Process dispersion. A spray drying to a microcapsule powder is generally possible, but has gentle to be done.

The microcapsules according to the invention can be processed well and have good tightness. With temperature increase in Usually at temperatures above 60 ° C they will be responsible for their ingredients permeable. this makes possible a targeted release of the ingredients, thus in the form of Microcapsules can be formulated directly and not cumbersome short must be added before use.

• a) Bei 40°C wurde die obige Wasserphase vorgelegt und nach Zugabe der Ölphase wurde mit einem schnelllaufenden Dissolverrührer bei 3500 Upm dispergiert. Nach 40 Minuten Dispergierung wurde eine stabile Emulsion erhalten.
• b) Die Emulsion wurde unter Rühren mit einem Ankerrührer über einen Zeitraum von 60 Minuten auf 70°C erwärmt, innerhalb von weiteren 60 Minuten auf eine Temperatur von 85°C erwärmt und bei dieser Temperatur eine Stunde gehalten. Es wurde Zugabe 1 zugegeben und die entstandene Mikrokapseldispersion unter Rühren innerhalb von 30 Minuten auf 20°C gekühlt, während Zulauf 1 zudosiert wurde.

The microcapsules according to the invention are suitable for use in thermal coating processes. Examples 1a-c water phase 380 g water 190 g a 5 wt .-% aqueous solution of methylhydroxypropyl cellulose (Culminal® MHPC ^® 100) 47.5 g a 10% strength by weight aqueous polyvinyl alcohol solution (Mowiol 15-79) 2.1 g a 2.5% by weight aqueous sodium nitrite solution oil phase 440g a low-viscosity silicone oil (Baysilone ^® M50) X g MONOMER BLEND, s. Table 1 0.7 g a 75% strength by weight solution of tert-butyl perpivalate in aliphatic hydrocarbons encore 5.38 g a 10% by weight aqueous solution of tert-butyl hydroperoxide Inlet 1 28.3 g a 1.1% by weight aqueous solution of ascorbic acid

• a) At 40 ° C, the above water phase was presented and after addition of the oil phase was dispersed with a high-speed Dissolverrührer at 3500 rpm. After 40 minutes of dispersion, a stable emulsion was obtained.
• b) The emulsion was heated with stirring with an anchor stirrer over a period of 60 minutes at 70 ° C, heated within another 60 minutes to a temperature of 85 ° C and held at this temperature for one hour. Addition 1 was added and the resulting microcapsule dispersion was cooled to 20 ° C. with stirring within 30 minutes, while feed 1 was metered in.

• MMA: Methylmethacrylat
• MAS: Methacrylsäure
• NBA: n-Butylacrylat
• BDA₂: Butandiacrylat

Beispiel 2 Wasserphase 235 g Wasser 95 g einer 5 gew.-%igen wässrigen Lösung von Methylhydroxypropylcellulose (Culminal^® MHPC 100) 23,8 g einer 10 gew.-%igen wässrigen Polyvinylalkohollösung (Mowiol 15-79) 1,1 g einer 2,5 gew.-%igen wässrigen Natriumnitritlösung Ölphase 220 g eines Polycarbodiimids auf Basis von 1,3-Bis-(-methyl-1-isocyanato-ethyl)benzol (TMXDI) mit einem NCO Gehalt von 8 Gew. % und einem Gehalt an Carbodiimidgruppen (N=C=N) von 15 Gew. % 12,6 g Methylmethacrylat 5,4 g n-Butylacrylat 0,38 g Ethylhexylthioglycolat 0,7 g einer 75 gew.-%igen Lösung von tert-Butylperpivalat in aliphatischen Kohlenwasserstoffen Zugabe 1 2,69 g einer 10 gew.-%igen wässrigen Lösung von tert-Butylhydroperoxid Zulauf 1 14,15 g einer 1,1 gew.-%igen wässrigen Lösung von Ascorbinsäure Zulauf 2 0,73 g einer 25 gew.-%igen Lösung von NaOH in Wasser 0,72 g Wasser Zulauf 3 3,35 g einer 30 gew.-%igen Dispersion von Viscalex HV 30 in Wasser (Verdicker auf Basis von Acrylsäure-Copolymerisaten)

• a) Bei 40°C wurde die obige Wasserphase vorgelegt. Nach Zugabe der Ölphase wurde mit einem schnelllaufenden Dissolverrührer bei 3500 Upm dispergiert. Nach 40 Minuten Dispergierung wurde eine stabile Emulsion erhalten.
• b) Die Emulsion wurde unter Rühren mit einem Ankerrührer über einen Zeitraum von 60 Minuten auf 70°C erwärmt, innerhalb von weiteren 60 Minuten auf eine Temperatur von 85°C erwärmt und bei dieser Temperatur eine Stunde gehalten. Es wurde Zugabe 1 zugegeben und die entstandene Mikrokapseldispersion unter Rühren innerhalb von 30 Minuten auf 20°C gekühlt, während Zulauf 1 zudosiert wurde.
• c) Bei Raumtemperatur wurden nacheinander Zulauf 2 und 3 unter Rühren zugegeben.

The monomer composition and the characteristics of the microcapsule dispersions obtained are shown in the table. Table: Monomer composition and specification of microcapsule dispersion example 1a 1b 1c Monomer Volume 49 g 49 g 23.2 g Monomer I 40% by weight of MMA 70% by weight of MMA 70% by weight of MMA Monomer I 20% by weight of MAS Monomer Ia 20 [% by weight] nBA 30 [% by weight] nBA 30 [% by weight] nBA Monomer II 20 [% by weight] BDA ₂ D [4,3] [microns] 4.55 5.38 5.39 chip 0.83 1.05 1.34 Solids content [%] 44.6 44.1 42.6

• MMA: methyl methacrylate
• MAS: methacrylic acid
• NBA: n-butyl acrylate
• BDA ₂ : butane diacrylate

Example 2 Water phase 235 g water 95 g a 5 wt .-% aqueous solution of methylhydroxypropyl cellulose (Culminal® MHPC ^® 100) 23.8 g a 10% strength by weight aqueous polyvinyl alcohol solution (Mowiol 15-79) 1.1 g a 2.5% by weight aqueous sodium nitrite solution oil phase 220 g of a polycarbodiimide based on 1,3-bis - (- methyl-1-isocyanato-ethyl) benzene (TMXDI) having an NCO content of 8 wt.% and a content of carbodiimide groups (N = C = N) of 15 wt. % 12.6 g methyl methacrylate 5.4 g n-butyl acrylate 0.38 g ethylhexyl 0.7 g a 75% strength by weight solution of tert-butyl perpivalate in aliphatic hydrocarbons Addition 1 2.69 g a 10% by weight aqueous solution of tert-butyl hydroperoxide Inlet 1 14.15 g a 1.1% by weight aqueous solution of ascorbic acid Inlet 2 0.73 g a 25% by weight solution of NaOH in water 0.72 g water Inlet 3 3.35 g a 30% strength by weight dispersion of Viscalex HV 30 in water (thickener based on acrylic acid copolymers)

• a) At 40 ° C, the above water phase was presented. After addition of the oil phase was dispersed with a high-speed dissolver at 3500 rpm. After 40 minutes of dispersion, a stable emulsion was obtained.
• b) The emulsion was heated with stirring with an anchor stirrer over a period of 60 minutes at 70 ° C, heated within another 60 minutes to a temperature of 85 ° C and held at this temperature for one hour. Addition 1 was added and the resulting microcapsule dispersion was cooled to 20 ° C. with stirring within 30 minutes, while feed 1 was metered in.
• c) At room temperature, feeds 2 and 3 were added successively with stirring.

It was a microcapsule dispersion with a solids content of 40.5% and an average particle size of 20 microns.

Claims (8)

Microcapsules comprising a capsule core and a capsule wall, wherein the capsule wall is constructed from From 30 to 100% by weight at least 2 mutually different monomers (monomers I) from the group comprising C ₁ -C ₂₄ -alkyl esters of acrylic and / or methacrylic acid, acrylic acid, methacrylic acid and maleic acid, 0 to 30% by weight one or more bi- or polyfunctional monomers (monomers II) which is insoluble or sparingly soluble in water, and 0 to 40% by weight one or more other monomers (monomers III) in each case based on the total weight of the monomers, wherein the monomers I comprise 10 to 90 wt .-%, based on the total amount of the monomers I, at least one monomer Ia whose homopolymer has a glass transition temperature ≤ 60 ° C. Microcapsules according to claim 1, wherein monomer Ia as Homopolymer has a glass transition temperature ≤ 50 ° C. Microcapsules according to claim 1 or 2, wherein monomer Ia is selected from the group comprising C ₁ -C ₂₄ alkyl esters of acrylic acid and n-butyl methacrylate. Microcapsules according to one of claims 1 to 3, wherein the capsule core is a lipophilic substance which is selected from the group consisting of aliphatic and aromatic hydrocarbon compounds, saturated or unsaturated C ₆ -C ₃₀ fatty acids, fatty alcohols, C ₅ -C ₃₀ fatty amines, Fatty acid esters, natural and synthetic waxes, halogenated hydrocarbons, silicone oils, adhesives, flavorings, fragrances, actives, dyes, color formers, pigments and crosslinkers. Microcapsules according to one of claims 1 to 4 in the form of an aqueous Dispersion. A process for the preparation of microcapsules according to claims 1 to 5, comprising a capsule core and a capsule wall, wherein the capsule wall is constructed from From 30 to 100% by weight at least 2 mutually different monomers (monomers I) from the group comprising C ₁ -C ₂₄ -alkyl esters of acrylic and / or methacrylic acid, acrylic acid, methacrylic acid and maleic acid, 0 to 30% by weight one or more bi- or polyfunctional monomers (monomers II) which is insoluble or sparingly soluble in water, and 0 to 40% by weight one or more other monomers (monomers III) in each case based on the total weight of the monomers, wherein the monomers I 10 to 90 wt .-%, based on the total amount of the monomers I comprise at least one monomer Ia whose homopolymer has a glass transition temperature ≤ 60 ° C by an oil-in Water emulsion in which the monomers, a radical initiator, a protective colloid and the lipophilic substance are present as a disperse phase, heated. Use of the microcapsules according to claims 1 to 5 for the thermal release of lipophilic len substances. Use of the microcapsules according to claims 1 to 5 in thermal Coating process.