EP1841517A1 - Coarse-particle microcapsule preparation - Google Patents

Abstract

The invention relates to a coarse-particle microcapsule preparation containing a microencapsulated PCM device and at least one polymer binding agent, the ratio of the surface to the volume of the particles obeying the relation (I). The invention also relates to a method for producing said preparation, and to the use thereof in heat exchangers and building materials.

Description

 Coarse-particled microcapsule preparation

description

The present invention relates to a coarse-particled microcapsule preparation comprising microencapsulated latent heat accumulators and one or more polymeric binders, wherein the ratio of surface area to volume of the particles obeys the following relation:

^ Surface area ₅ l / volume and process for their preparation and their use in heat exchangers and building materials.

In recent years, building materials with latent heat storage have been investigated as a new combination of materials. Their function is based on the conversion enthalpy occurring during the solid / liquid phase transition, which means an energy absorption or energy release to the environment. They can thus be used for temperature maintenance in a defined temperature range. Since the latent heat storage materials are also liquid depending on the temperature, they can not be processed directly with building materials, because emissions to the room air and the separation of the building material would be to be feared.

EP-A-1 029 018 teaches the use of microcapsules having a capsule wall of a highly crosslinked methacrylic acid ester polymer and a latent heat storage core in binders such as concrete or gypsum. However, since the capsule walls only have a thickness in the range of 5 to 500 nm, they are very sensitive to pressure, an effect used in their use in copying papers. However, this limits their usability.

DE-A-101 39 171 describes the use of microencapsulated latent heat storage materials in plasterboard. Further, the prior US application Ser. No 60/573420 the use of microencapsulated latent heat storage materials in chipboard together with melamine formaldehyde resins as a binder.

In all these different applications, the microcapsules are used as powders with particle sizes in the range of 1 to 50 μm. However, powders are often difficult to process. The result is formulations with a high binder content. If the ratio of microcapsules to binder, calculated as solids in terms of their sum, is considered in the above-described documents, the proportion of microcapsules ranges up to a maximum of 30% by weight and the binder content is 70% by weight or more. An optimization by increasing the latent heat storage content, which indeed corresponds to the microcapsule content, was therefore desirable. DE-A-102 00 316 teaches the production of plastic injection molded parts from plastic granules to which carrier material parts with latent heat accumulators are added from the injection into the mold cavity. The capillary spaces of the mineral support materials have an absorbent solid structure in which the latent heat storage materials are held. However, capillary spaces in the carrier material are ultimately open systems, so that always with temperature increases, when the latent heat storage change into the liquid phase, with the leakage of liquid wax is to be expected.

JP 2001098259 describes the mixing of microencapsulated latent heat storage material with water and cement and comminution of the hardened material to particle sizes> 1 mm. Such particles are used as fillings in walls and floors.

JP 2001303032 teaches a microcapsule extrudate of a silica gel pigment and a microcapsule dispersion whose microcapsules have a capsule core of latent heat storage material.

US Pat. No. 6,703,127 teaches macroparticles formed by suspending microencapsulated latent heat storage material in a solution of a thickener and curing the drops by dropping into a crosslinker solution. Such hardened drops have significantly poorer performance properties.

GB 870 476 describes macrocapsules containing microcapsules with a film-forming wall material, such as gelatin, which are held together in clusters by a capsule wall of such a film-forming polymer. Such macro capsules have much poorer performance properties since they ^• tend to swell and are sensitive to bacteria.

EP-A-1416027 discloses that latent heat storage material is mixed and extruded with expanded graphite and that the resulting particles can be used as a bed. Here, too, segregation and continuous emissions to the room air threaten because the used latent heat storage material is not encapsulated.

DE-A-100 58 101 describes latent heat accumulator body with an outer shell body made of hard plastic such as polymethyl methacrylate and a filling of latent heat storage material. These bodies are produced by means of a two-component injection method. The latent heat storage material is gelatinized by the addition of block copolymers. In this way, by concluding the rolling of the body large heat storage plates are produced. Here, as in DE-A-102 00 316, the latent heat storage materials are processed directly and achieved stabilization on the wax additives.

DE-A-100 48 536 finally teaches a dynamic latent heat storage with a gel-like thickened latent heat storage material, between the small particles of a heat transfer medium flows. The operating principle is based on the fact that the heat transfer fluid evaporates and condenses on contact with the latent heat storage and releases the energy to it. The problem, however, is that the particles are softened by heat and the flow paths are narrowed.

The use of gel-bonded latent heat storage materials and an additional support structure also has the consequence that the proportion of the latent heat storage material based on the total weight of the preparation is less than 50% by weight.

WO 200224789 is concerned with polymer blends of polyethylene obtained by mixing molten polyethylene with microencapsulated latent heat accumulators and subsequent comminution and extruding them together with polypropylene in a second processing step. However, such pellets obtained have a very low latent heat storage content, so that the heat storage capacity is low.

The earlier application PCT / EP 2005/008354 teaches coarse-particled microcapsule formulations with microcapsule walls of polymethyl methacrylate and a binder polymer having film-forming properties.

Therefore, it was an aspect of the present invention to find a latent heat storage preparation, the proportion of latent heat storage material is high and thus it has a high storage energy and even better efficiency.

Furthermore, the latent heat storage preparation should be used advantageously in heat exchangers and in open systems, such as for centralized and decentralized ventilation.

Accordingly, the above-mentioned coarse microcapsule preparation containing one or more microencapsulated latent heat storage materials and one or more polymeric binders has been found.

For the purposes of the present invention, coarse-particle is to be understood as meaning particles whose dimensions range from 200 μm to 5 cm, preferably 500 μm to 2 cm. These particles may have an amorphous, spherical or even rod-shaped form, depending on the respective production method. In Cases of spherical structures, the average diameter is 200 microns to 2 cm, preferably 500 microns to 1 cm. Rod-like shapes have a maximum length of 5 cm in their longest extent, usually in the range of 1 mm to 2 cm. The shortest dimension has a value of at least 200 μm, as a rule from 500 μm to 10 mm, preferably 500 μm to 5 mm. For the rod-like particles, the length to diameter ratio will usually not exceed the value of 10: 1, preferably 5: 1.

In the preferred microcapsule preparations according to the invention, 90% by weight of the particles are> 500 μm, preferably> 700 μm, in particular> 1 mm, determined by sieving technique.

The particles of the present invention in one embodiment are asymmetric aggregates of powder particles having only approximately the shape of a sphere, a rod, a cylinder, and whose surface is often uneven and jagged. Such particles are often referred to as granules or agglomerate. Another form of agglomerates are pellets or pellets, as known from the pharmaceutical industry.

The particles of the invention may have any geometric shapes. For example, geometric primitives can be spheres, cylinders, cubes, cuboids, prisms, pyramids, cones, truncated cones, and truncated pyramids. Star strands, cross strands, rib strands and trilobes are also suitable. The geometric bodies can be hollow as well as filled. Cavities, such as incorporated tubes, increase the surface area of the geometric body while reducing its volume. The figures enclosed with this document show a few geometrical bodies which can be considered in principle. FIGS. 7 to 10 each show, in addition to the body (A), a view of the body from above (B). According to the invention, the ratio of surface to volume of the particles obeys the following relation:

Preferably, these are ≥ 2.6, more preferably ≥ 2.8, and especially ≥ 3.0.

The terms surface and volume are to be understood as surfaces and volumes which the eye is able to visually perceive when viewing the geometric body. That is, internal volumes and surfaces resulting from finely divided pores and / or cracks in the material of the geometric body are not included. The pore area of the particles according to the invention measured by mercury porosimetry according to DIN 66133 is preferably 2-100 m ² / g, in particular 30-100 m ² / g.

According to one embodiment, the coarse-particle preparations according to the invention consist of at least 90% by weight, predominantly of microcapsules and polymeric binders.

According to another embodiment, the preparations according to the invention comprise at least 80% by weight of microcapsules and polymeric binder. According to this embodiment, the preparation contains 2-20% by weight of graphite based on the total weight of the coarse-particle preparation.

The binder content, calculated as solids, is preferably 1-40% by weight, preferably 1-30% by weight, more preferably 1-25% by weight, in particular 1-20% by weight and very particularly preferably 2% 15% by weight, based on the total weight of the coarse-particle preparation.

Based on their total weight, preferred formulations contain 55-94% by weight of latent heat storage material, 1-40% by weight, preferably 1-30% by weight of polymeric binder calculated as solids, microcapsule wall material and 0-10% by weight of other additives.

Particular preference is given to preparations, in particular granules of 85-99% by weight of microencapsulated latent heat accumulators, 1-15% by weight of polymeric binder calculated as solids and 0-5% by weight of other additives.

Since the coarse-particle microcapsule preparations are usually prepared by processing with water or aqueous substances, the preparations may still contain residues of water. The amount of residual moisture is usually from 0 to about 2 wt .-% based on the total weight.

The microcapsules contained in the preparation are particles having a capsule core predominantly, more than 95% by weight, of latent heat storage materials and a polymer as capsule wall. The capsule core is solid or liquid depending on the temperature. The average particle size of the capsules (Z means by means of light scattering) is 0.5 to 100 μm, preferably 1 to 80 μm, in particular 1 to 50 μm. The weight ratio of capsule core to capsule wall is generally from 50:50 to 95: 5. Preferred is a core / wall ratio of 70:30 to 93: 7.

Latent heat storage materials are by definition substances which are in the Temperature range in which a heat transfer is to be made, have a Phasenübergarig. Preferably, the latent heat storage materials have a solid / liquid phase transition in the temperature range from -20 to 12O ⁰ C. As a rule, the latent heat storage material is an organic, preferably lipophilic substance.

Suitable substances may be mentioned by way of example:

- aliphatic hydrocarbon compounds such as saturated or unsaturated Cio-C ₄ o-hydrocarbons, branched or preferably linear, are, for example, 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-pentacosane, n-hexacosane, n-heptacosane, n-octacosane and cyclic hydrocarbons, eg cyclohexane, cyclooctane, cyclodecane;

aromatic hydrocarbon compounds, such as benzene, naphthalene, biphenyl, o- or n-terphenyl, C 1 -C ₄₀ -alkyl-substituted aromatic hydrocarbons, such as dodecylbenzene, tetradecylbenzene, hexadecylbenzene, hexylnaphthalene or decylnaphthalene;

saturated or unsaturated C ₆ -C 30 -fatty acids, such as lauric, stearic, oleic or behenic acid, preferably electic mixtures of decanoic acid with, for example, myristic, palmitic or lauric acid;

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 further reactions;

- C ₆ -C ₃ o-fatty amines such as decylamine, dodecylamine, tetradecylamine or hexadecylamine;

Esters such as C-Ci _O alkyl esters of fatty acids, such as propyl, methyl stearate or methyl, and preferably their eutectic mixtures, or methyl;

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 hard waxes;

halogenated hydrocarbons such as chlorinated paraffin, bromoctadecane, bromopentadecane, bromononadecane, bromeicosane, bromodocosan. Furthermore, mixtures of these substances are suitable, as long as it does not come to a melting point lowering outside the desired range, or the heat of fusion of the mixture is too low for a meaningful application.

Advantageously, for example, the use of pure n-alkanes, n-alkanes with a purity of greater than 80% or of alkane mixtures, as obtained as a technical distillate and are commercially available as such.

Furthermore, it may be advantageous to add soluble compounds to the capsule core-forming substances so as to prevent the freezing point depression which sometimes occurs with the nonpolar substances. It is advantageous to use, as described in US Pat. No. 5,456,852, compounds having a melting point 20 to 120 K higher than the actual core substance. Suitable compounds are the fatty acids mentioned above as lipophilic substances, fatty alcohols, fatty amides and aliphatic hydrocarbon compounds. They are added in amounts of from 0.1 to 10% by weight, based on the capsule core.

Depending on the temperature range in which the heat storage are desired, the latent heat storage materials are selected. For example, used for heat storage in building materials in a moderate climate preferred latent heat storage materials whose solid / liquid phase transition in the temperature range of 0 to 6O ⁰ C. Thus, selects a rule for indoor applications individual substances or mixtures with conversion temperatures of 15 to 3O ⁰ C. In solar applications as a storage medium or avoiding the overheating of transparent insulation, EP-A-333 described 145 as in the are mainly transformation temperatures of 30 - 60 ⁰ C suitable.

Preferred latent heat storage materials are aliphatic hydrocarbons, particularly preferably those listed above by way of example. In particular, aliphatic hydrocarbons having 14 to 20 carbon atoms and mixtures thereof are preferred.

In principle, the materials known for the microcapsules for copying papers can be used as the polymer for the capsule wall. Thus, for example, it is possible to encapsulate the latent heat storage materials in gelatin with other polymers according to the processes described in GB-A 870476, US Pat. No. 2,800,457, US Pat. No. 3,041,289.

Preferred wall materials for the capsule wall of the microcapsules, since they are very resistant to aging, are thermosetting polymers. Under thermosetting wall materials are to be understood that not due to the high degree of crosslinking soften, but decompose at high temperatures. Suitable thermosetting wall materials are, for example, highly crosslinked formaldehyde resins, highly crosslinked polyureas and highly crosslinked polyurethanes, and highly crosslinked acrylic and methacrylic ester polymers.

Formaldehyde resins are understood as meaning reaction products of formaldehyde with

- Triazines such as melamine

Carbamides such as urea phenols such as phenol, m-cresol and resorcinol

Amino and amido compounds such as aniline, p-toluenesulfonamide, ethyleneurea and guanidine,

or their mixtures.

As the capsule wall material preferred formaldehyde resins are urea-formaldehyde resins, urea-resorcinol-formaldehyde resins, urea-melamine resins and melamine-formaldehyde resins. Likewise preferred are the C 1 -C ₄ -alkyl, in particular methyl ethers of these formaldehyde resins, and also the mixtures with these formaldehyde resins. In particular, melamine-formaldehyde resins and / or their methyl ethers are preferred.

In the methods known from copying papers, the resins are used as prepolymers. The prepolymer is still soluble in the aqueous phase and migrates in the course of the polycondensation at the interface and encloses the

Oil droplets. Processes for microencapsulation with formaldehyde resins are well known and described for example in EP-A-562 344 and EP-A-974 394.

Capsule walls of polyureas and polyurethanes are also known from the copying papers. The capsule walls are formed by reaction of NH ₂ groups or OH-containing reactants with di- and / or polyisocyanates. Suitable isocyanates are, for example, ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate and 2,4- and 2,6-toluene diisocyanate. Also mentioned are polyisocyanates such as biuret derivatives, polyuretonimines and isocyanurates. Suitable reactants are: hydrazine, guanidine and its salts, hydroxylamine, di- and polyamines and amino alcohols. Such interfacial polyaddition processes are known, for example, from US 4,021,595, EP-A 0 392 876 and EP-A 0 535 384.

Preference is given to microcapsules whose capsule wall is a highly crosslinked methacrylic ester polymer. The degree of crosslinking is achieved with a crosslinker> 10 wt .-% based on the total polymer. In the preferred microcapsules, the wall-forming polymers of 10 to 100 wt .-%, preferably 30 to 95 wt .-% of one or more C ₁ -C ₂₄ alkyl esters of acrylic and / or methacrylic acid as monomers I constructed. In addition, the polymers may contain up to 80% by weight, preferably 5 to 60% by weight, in particular 10 to 50% by weight, of a bi- or polyfunctional monomer as monomers II, which is insoluble or sparingly soluble in water, incorporated in copolymerized form. In addition, the polymers may contain up to 90% by weight, preferably up to 50% by weight, in particular up to 30% by weight, of other monomers III in copolymerized form.

Suitable monomers I are C ₁ -C ₂₄ -alkyl esters of acrylic and / or methacrylic acid. Particularly preferred monomers I are methyl, ethyl, n-propyl and n-butyl acrylate and / or the corresponding methacrylates. Iso-propyl, isobutyl, sec-butyl and tert-butyl acrylate and the corresponding methacrylates are preferred. Further, methacrylonitrile is mentioned. Generally, the methacrylates are preferred.

Suitable monomers II are bi- or polyfunctional monomers which are insoluble or sparingly soluble in water but have good to limited solubility in the lipophilic substance. Sparingly is less than 60 g / l to understand at 2O ⁰ C a solubility. By bi- or polyfunctional monomers is meant compounds having at least 2 non-conjugated ethylenic double bonds. In particular, divinyl and polyvinyl monomers come into consideration, which cause cross-linking of the capsule wall during the polymerization.

Preferred bifunctional monomers are the diesters of diols with acrylic acid or methacrylic acid, furthermore the diallyl and divinyl ethers of these diols.

Preferred divinyl monomers are ethanediol diacrylate, divinylbenzene, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, methallyl methacrylamide and allyl methacrylate. Particular preference is given to propanediol, butanediol, pentanediol and hexanediol diacrylate or the corresponding methacrylates.

Preferred polyvinyl monomers are trimethylolpropane triacrylate and methacrylate, pentaerythritol triallyl ether and pentaerythritol tetraacrylate.

As monomers Hl other monomers into consideration, preferred are monomers IHa such as vinyl acetate, vinyl propionate and vinylpyridine.

Particularly preferred are the water-soluble monomers Illb, e.g. Acrylonitrile, methacrylamide, acrylic acid, methacrylic acid, itaconic acid, maleic acid,

Maleic anhydride, N-vinylpyrrolidone, 2-hydroxyethyl acrylate and methacrylate and acrylamido-2-methylpropanesulfonic acid. In addition, N- Methylolacrylamide, N-methylolmethacrylamide, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate.

According to a further preferred embodiment, the wall-forming polymers of 30 to 90 wt .-% methacrylic acid, 10 to 70 wt .-% of an alkyl ester of (meth) acrylic acid, preferably methyl methacrylate, tert-butyl methacrylate, phenyl methacrylate and cyclohexyl methacrylate, and 0 to 40 wt .-% further ethylenically unsaturated monomers formed. These further ethylenically unsaturated monomers may be the monomers I, II or III hitherto not mentioned for this embodiment. Since they usually have no significant influence on the microcapsules of this embodiment formed, their proportion is preferably <20 wt .-%, in particular <10 wt .-%. Such microcapsules and their preparation are described in EP-A-1 251 954, to which reference is expressly made.

The microcapsules suitable for use according to the invention can be prepared by a so-called in situ polymerization.

The preferred microcapsules and their preparation are known from EP-A-457 154, DE-A-10 139 171, DE-A-102 30 581 and EP-A-1 321 182, to which reference is expressly made. Thus, the microcapsules are prepared by preparing from the monomers, a radical initiator, a protective colloid and the lipophilic substance to be encapsulated a stable oil-in-water emulsion in which they are present as a disperse phase. Subsequently, the polymerization of the monomers is initiated by heating and controlled by further increase in temperature, wherein the resulting polymers form the capsule wall, which encloses the lipophilic substance.

In general, the polymerization is carried out at 20 to 100 ⁰ C, preferably at 40 to 8O ⁰ C. Of course, the dispersion and polymerization temperature should be above the melting temperature of the lipophilic substances.

After reaching the final temperature, the polymerization is expediently continued for a time of up to 2 hours in order to lower residual monomer contents. 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 organic volatile 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 done chemically, as described in WO 9924525, advantageously by redox-initiated polymerization, as described in DE-A-4 435 423, DE-A ~ 4419518 and DE-A-4435422. It is possible in this way to produce microcapsules having a mean 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 speed, the protective colloid and its concentration.

Preferred protective colloids are water-soluble polymers, since these lower the surface tension of the water from 73 mN / tn to a maximum of 45 to 70 mN / m and thus ensure the formation of closed capsule walls and microcapsules with preferred particle sizes between 1 and 30 .mu.m, preferably 3 and 12 .mu.m, form.

In general, the microcapsules are prepared in the presence of at least one organic protective colloid, which may be both anionic and neutral. It is also possible to use anionic and nonionic protective colloids together. Preference is given to using inorganic protective colloids, optionally mixed with organic protective colloids or nonionic protective colloids.

Organic neutral protective colloids are cellulose derivatives such as hydroxyethylcellulose, methylhydroxyethylcellulose, methylcellulose and carboxymethylcellulose, polyvinylpyrrolidone, copolymers of vinylpyrrolidone, gelatin, gum arabic, xanthan, sodium alginate, casein, polyethylene glycols, preferably polyvinyl alcohol and partially hydrolyzed polyvinyl acetates and methylhydroxypropylcellulose.

Suitable anionic protective colloids are polymethacrylic acid, the copolymers of sulfoethyl acrylate and methacrylate, sulfopropyl acrylate and methacrylate, N- (sulfoethyl) -maleimide, 2-acrylamido-2-alkylsulfonic acids, styrenesulfonic acid and vinylsulfonic acid.

Preferred anionic protective colloids are naphthalenesulfonic acid and naphthalenesulfonic acid-formaldehyde condensates and above all polyacrylic acids and phenolsulfonic acid-formaldehyde condensates.

The anionic and nonionic protective colloids are generally used in amounts of from 0.1 to 10% by weight, based on the water phase of the emulsion.

Preference is given to inorganic protective colloids, so-called Pickering systems, 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 its use is described in EP-A-1 029 018 and EP-A-1 321 182, to the contents of which reference is expressly made.

A Pickering system can consist of the solid particles alone or in addition of auxiliaries which improve the dispersibility of the particles in water or the wettability of the particles by the lipophilic phase.

The inorganic solid particles may be 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, aluminum oxide, aluminum hydroxide and zinc sulfide. Silicates, bentonite, hydroxyapatite and hydrotalcites are also mentioned. Particularly preferred are highly disperse silicas, magnesium pyrophosphate 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 produced by precipitation as described in EP-A-1 029 018 and EP-A-1 321 182.

The highly dispersed silicas can be dispersed as fine, solid particles in water. But it is also possible to use so-called colloidal dispersions of silica in water. The colloidal dispersions are alkaline, aqueous mixtures of silica. In the alkaline pH range, the particles are swollen and stable in water. For use of these dispersions as Pickering system, it is advantageous if the pH of the oil-in-water emulsion is adjusted to pH 2 to 7 with an acid.

The inorganic protective colloids are generally used in amounts of 0.5 to 15 wt .-%, based on the water phase.

In general, the organic neutral protective colloids are used in amounts of from 0.1 to 15% by weight, preferably from 0.5 to 10% by weight, based on the water phase.

The dispersing conditions for preparing the stable oil-in-water emulsion are preferably chosen in a manner known per se such that the oil droplets have the size of the desired microcapsules.

The microcapsule dispersions obtained by the polymerization give a free-flowing capsule powder when spray-dried. The spray-drying of the microcapsule dispersion can be carried out in a customary manner. In general, so Proceeding that the inlet temperature of the hot air flow in the range of 100 to 200 ⁰ C, preferably 120 to 16O ⁰ C, and the outlet temperature of the hot air flow in the range of 30 to 90 ⁰ C, preferably 60 to 80 ° C. The spraying of the aqueous polymer dispersion in the hot air stream can be effected, for example, by means of single-component or multi-component nozzles or via a rotating disk. The deposition of the polymer powder is usually carried out using cyclones or filter separators. The sprayed aqueous polymer dispersion and the hot air stream are preferably conducted in parallel.

Optionally, spray-auxiliaries are added to the spray-drying to facilitate spray-drying or to set certain powder properties, e.g. Low dust, free-flowing or improved redispersibility. A variety of spraying aids are familiar to the person skilled in the art. Examples thereof can be found in DE-A 19 629 525, DE-A 19 629 526, DE-A 2 214 410, DE-A 2445813, EP-A 407 889 or EP-A 784 449. Advantageous spray aids are, for example, water-soluble polymers of Type polyvinyl alcohol or partially hydrolyzed polyvinyl acetates, cellulose derivatives such as hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, methylhydroxyethylcellulose and methylhydroxypropylcellulose, polyvinylpyrrolidone, copolymers of vinylpyrrolidone, gelatin, preferably polyvinyl alcohol and partially hydrolyzed polyvinyl acetates and methylhydroxypropylcellulose.

Polymeric binders are well known. These are fluid systems which contain a disperse phase in aqueous dispersion medium consisting of a plurality of intertwined polymer chains, which are known as polymer pellets or polymer particles, in disperse distribution. The weight-average diameter of the polymer particles is often in the range from 10 to 1000 nm, often 50 to 500 nm or 100 to 400 nm. In addition to the polymer (binder polymer), the polymeric binder contains the auxiliaries described below. The binder polymers according to the invention preferably have thermoplastic properties. By thermoplastic is meant that the binder polymers soften without decomposition above the glass transition temperature.

According to the invention can be used as polymeric binders (binder polymers) basically all finely divided polymers, which in the

Processing temperature are able to form a polymer film, i. are film-forming at these temperatures. According to a preferred variant, the polymers are not water-soluble. This makes it possible to use the coarse-particle preparations according to the invention in moist or aqueous systems.

According to the invention, those polymers can be used whose glass transition temperature is -60 to + 15O ⁰ C, often -20 to +130 ⁰ C and often 0 to + 12O ⁰ C. is. By the glass transition temperature (T ₉ ) is meant the limit of the glass transition temperature, which according to G. Kanig (Kolloid-Zeitschrift & Zeitschrift fur Polymere, Vol. 190, page 1, Equation 1) tends to increase with increasing molecular weight. The glass transition temperature is determined by the DSC method (differential scanning calorimetry, 20 K / min, midpoint measurement, DIN 53 765).

Polymers are very particularly preferably with a glass transition temperature in the range of 40 to 120 ⁰ C. In general, these are processed at temperatures in the range of 20 to 12O ⁰ C. Coarse-particle compositions obtained in this way exhibit particularly good mechanical stability and have good abrasion values.

The glass transition temperature of polymers which are composed of ethylenically unsaturated monomers can be controlled in a known manner via the monomer composition (TG Fox, Bull. Am. Phys. Soc. (Ser. II) 1, 123 [1956] and Ullmanns Enzyklopedia of Industrial Chemistry 5th ed., Vol. A21, Weinheim (1989) p. 169).

Preferred polymers are composed of ethylenically unsaturated monomers M which are generally at least 80% by weight, in particular at least 90% by weight, of ethylenically unsaturated monomers A which are selected from monomers having a water solubility <10 g / l (25 ^° C.) and 1 bar) and their mixtures with acrylonitrile and / or methacrylonitrile, the proportion of acrylonitrile and methacrylonitrile usually does not exceed 30 wt .-% and eg 1 to 30 wt .-% or 5 to 25 wt .-% of the monomers A is. In addition, the polymers contain from 0.5 to 20 wt .-% of the monomers A different monomers B. Here and below are all quantities for monomers in wt .-% based on 100 wt .-% of monomers M.

Monomers A are usually simply ethylenically unsaturated or conjugated diolefins. Examples of monomers A are:

Esters of an α, ß-ethylenically unsaturated C ₃ -C ₆ monocarboxylic acid or C ₄ -C ₈ - dicarboxylic acid with a Ci-C- _t o -alkanol. These are preferably esters of acrylic acid or methacrylic acid, such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. ;

vinyl aromatic compounds such as styrene, 4-chlorostyrene, 2-methylstyrene, etc .;

Vinyl esters of aliphatic carboxylic acids having preferably 1 to 10 carbon atoms, such as vinyl acetate, vinyl propoxide, vinyl laurate, vinyl stearate, vinyl versatate, etc .; Olefins, such as ethylene or propylene;

conjugated diolefins, such as butadiene or isoprene;

- Vinyl chloride or vinylidene chloride.

Preferred film-forming polymers are selected from the polymer classes I to IV listed below:

I) copolymers of styrene with alkyl (acrylates), ie copolymers containing in copolymerized form as monomer A styrene and at least one C ₁ -C 10 -alkyl ester of acrylic acid and optionally one or more C ₁ -C 10 -alkyl esters of methacrylic acid;

II) copolymers of styrene with butadiene, ie copolymers as monomer A, styrene and butadiene, and optionally (meth) acrylate of Ci-C ₈ - alkanols, acrylonitrile and / or methacrylonitrile as polymerized units;

III) Homopolymers and Copolymers of Acrylic (meth) acrylates (pure acrylates), i. Homopolymers and copolymers which as monomers A at least one C 1 -C 10 -alkyl ester of

Acrylic acid and / or a C _r Ci ₀ alkyl ester of methacrylic acid in copolymerized form, in particular copolymers containing as monomers A methyl methacrylate, at least one Ci-C ₁₀ alkyl esters of acrylic acid and optionally a C ₂ - Cio-alkyl esters of methacrylic acid in copolymerized form;

IV) homopolymers of vinyl esters of aliphatic carboxylic acids and copolymers of vinyl esters of aliphatic carboxylic acids with olefins and / or alkyl (meth) acrylates, ie homopolymers and copolymers containing as monomer A at least one vinyl ester of an aliphatic carboxylic acid having 2 to 10 carbon atoms and optionally one or more C ₂ -C ₆ -olefins and / or optionally one or more CrCio-alkyl esters of acrylic acid and / or methacrylic acid in copolymerized form;

V) Copolymers of styrene with acrylonitrile.

Typical C 1 -C 10 -alkyl esters of acrylic acid in the copolymers of class I to IV are ethyl acrylate, n-butyl acrylate, tert-butyl acrylate, n-hexyl acrylate and 2-ethylhexyl acrylate.

Typical copolymers of class I contain, as monomers A, 20 to 80% by weight and in particular 30 to 70% by weight of styrene and 20 to 80% by weight, in particular 30 to 70% by weight, of at least one C _r C ₁₀ Alkyl esters of acrylic acid such as n-butyl acrylate, Ethyl acrylate or 2-ethylhexyl acrylate, in each case based on the total amount of monomers A.

Typical copolymers of class II comprise, as monomers A, in each case based on the total amount of monomers A _{1, from} 30 to 85% by weight, preferably from 40 to 80% by weight and particularly preferably from 50 to 75% by weight of styrene and from 15 to 70 Wt .-%, preferably 20 to 60 wt .-% and particularly preferably 25 to 50 wt .-% butadiene, wherein 5 to 20 wt .-% of the aforementioned monomers A by (meth) acrylic acid esters of Ci-C ₈ alkanols and or may be replaced by acrylonitrile or methacrylonitrile.

Typical copolymers of class III comprise, as monomers A, in each case based on the total amount of monomers A, from 20 to 80% by weight, preferably from 30 to 70% by weight, of methyl methacrylate and at least one further, preferably one or two, further monomers selected from Acrylsäureestem of CrC ₁₀ alkanols, especially n-butyl acrylate, 2-ethylhexyl acrylate and ethyl acrylate and optionally one

Methacrylsäureester of a C ₂ -C ₁₀ alkanol copolymerized in a total amount of 20 to 80% by weight and preferably 30 to 70 wt .-%.

Typical homopolymers and copolymers of class IV comprise, as monomers A, in each case based on the total amount of monomers A, from 30 to 100% by weight, preferably from 40 to 100% by weight and particularly preferably from 50 to 100% by weight, of a vinyl ester an aliphatic carboxylic acid, in particular vinyl acetate and 0 to 70 wt .-%, preferably 0 to 60 wt .-% and particularly preferably 0 to 50 wt .-% of a C ₂ -C ₆ - olefin, in particular ethylene and optionally one or two further Monomers selected from (meth) acrylic acid esters of CrC ₁₀ alkanols in an amount of 1 to 15 wt .-% copolymerized.

Among the above-mentioned polymers, the polymers of classes IV and V are particularly suitable.

Homopolymers of vinyl esters of aliphatic carboxylic acids, in particular of vinyl acetate, are preferred. A specific embodiment are those which are stabilized with protective colloids such as polyvinylpyrrolidone and anionic emulsifiers. Such an embodiment is described in WO 02/26845, to which reference is expressly made.

Suitable monomers B are in principle all monomers which are different from the abovementioned monomers and copolymerizable with the monomers A. Such monomers are known in the art and usually serve to modify the properties of the polymer. Preferred monomers B are selected from monoethylenically unsaturated mono- and dicarboxylic acids having 3 to 8 C atoms, in particular acrylic acid, methacrylic acid, itaconic acid, their amides such as acrylamide and methacrylamide, their N-alkylolamides such as N-methylolacrylamide and N-methylolmethacrylamide, their hydroxyl groups. C 1 -C ₄ -alkyl esters, such as 2-hydroxyethyl acrylate, 2- and 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2- and 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate and monoethylenically unsaturated monomers with oligoalkylene oxide chains, preferably with polyethylene oxide chains with degrees of oligomerization preferably in the range from 2 to 200, for example monovinyl and monoallyl ethers of oligoethylene glycols and also esters of acrylic acid, maleic acid or methacrylic acid with oligoethylene glycols.

The proportion of monomers having acid groups is preferably not more than 10% by weight and more preferably not more than 5% by weight, e.g. 0.1 to 5 wt .-%, based on the monomers M. The proportion of hydroxyalkyl esters and monomers with

Oligoalkylenoxidketten is, if contained, preferably in the range of 0.1 to 20 wt .-% and in particular in the range of 1 to 10 wt .-%, based on the monomers M. The proportion of amides and N-alkylol amides is if included, preferably in the range of 0.1 to 5 wt .-%. ,

In addition to the abovementioned monomers B, other monomers B also include crosslinking monomers, such as glycidyl ethers and esters, for example vinyl, allyl and methallyl glycidyl ethers, glycidyl acrylate and methacrylate, the diacetonylamides of the abovementioned ethylenically unsaturated carboxylic acids, for example diacetone (meth) acrylamide , and the esters of acetylacetic acid with the abovementioned hydroxyalkyl esters of ethylenically unsaturated carboxylic acids, for example acetylacetoxyethyl (meth) acrylate. Monomers B furthermore include compounds which have two nonconjugated, ethylenically unsaturated bonds, for example the di- and oligoesters of polyhydric alcohols with α, β-monoethylenically unsaturated C ₃ -C ₁₀ -monocarboxylic acids, such as alkylene glycol diacrylates and dimethacrylates, for example ethylene glycol diacrylate , 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylate, propylene glycol diacrylate, and also divinylbenzene, vinyl methacrylate, vinyl acrylate, allyl methacrylate, allyl acrylate, diallyl maleate, diallyl fumarate, methylenebisacrylamide, cyclopentadienyl acrylate, tricyclodecenyl (meth) acrylate, N, N'-divinylimidazoline 2-one or triallyl cyanurate. The proportion of crosslinking monomers is generally not more than 1 wt .-%, based on the total amount of monomer and will not exceed 0.1 wt .-% in particular.

Also suitable as monomers B are vinylsilanes, for example vinyltrialkoxysilanes. These are, if desired, used in an amount of 0.01 to 1 wt .-%, based on the total amount of monomers in the preparation of the polymers. Aqueous polymer dispersions are accessible in particular by free-radically initiated aqueous emulsion polymerization of ethylenically unsaturated monomers. This method has been described many times and is therefore sufficiently known to the person skilled in the art [cf. for example, Encyclopedia of Polymer Science and Engineering, Vol. 8, pp. 659-677, John Wiley & Sons, Inc., 1987; DC Blackley, Emulsion Polymerization, pp. 155-465, Applied Science Publishers, Ltd., Essex, 1975; . DC Blackley, polymer latices, 2 ^nd Edition, Vol 1, pages 33 to 415, Chapman & Hall, 1997; H. Warson, The Applications of Synthetic Resin Emulsions, pages 49 to 244, Ernest Benn, Ltd., London, 1972; D. Diederich, Chemistry in our Time 1990, 24, pages 135 to 142, Verlag Chemie, Weinheim; J. Piirma, Emulsion Polymerization, pages 1 to 287, Academic Press, 1982; F. Hölscher, dispersions of synthetic high polymers, pages 1 to 160, Springer-Verlag, Berlin, 1969 and the patent DE-A 40 03 422]. The free-radically initiated aqueous emulsion polymerization is usually carried out by dispersing the ethylenically unsaturated monomers, frequently with the concomitant use of surface-active substances, in an aqueous medium and polymerizing them by means of at least one free-radical polymerization initiator. Frequently, in the aqueous polymer dispersions obtained, the residual contents of unreacted monomers are also chemical and / or physical methods known to the person skilled in the art [see, for example, EP-A 771328, DE-A 19624299, DE-A 19621027, DE-A 19741184, DE-A 1974,187, DE-A 19805122, DE-A 19828183, DE-A 19839199, DE-A 19840586 and 19847115], the polymer solids content is adjusted by dilution or concentration to a desired value or the aqueous polymer dispersion further conventional additives, such as bactericidal or foam-suppressing Additives added. Frequently, the polymer solids contents of the aqueous

Polymerisatdispersionen 30 to 80 wt .-%, 40 to 70 wt .-% or 45 to 65 wt .-%. Likewise preferred are the polymer powders prepared from the polymer dispersions and also aqueous dispersions obtainable by redispersing the polymer powders in water. Both aqueous polymer dispersions and the powder produced therefrom are also commercially available, eg under the trademarks ACRONAL ^®, STYRONAL® ^®, Butofan ^®, Styrofan ^® and Kollicoat ^® of BASF Aktiengesellschaft, Ludwigshafen, Germany, VINNOFIL ^® and VINNAPAS ^® from. Wacker Chemie GmbH, Burghausen, and RHODIMAX ^® from. Rhodia SA

Suitable surface-active substances for emulsion polymerization are the emulsifiers and protective colloids customarily used for the emulsion polymerization. Preferred emulsifiers are anionic and nonionic emulsifiers which, in contrast to the protective colloids, generally have a molecular weight below 2000 g / mol and in amounts of up to 0.2 to 10% by weight, preferably 0.5 to 5% by weight. %, based on the polymer in the dispersion or on the monomers M to be polymerized. Such protective colloids are already mentioned by way of example for the formation of microcapsules.

The anionic emulsifiers include alkali metal and ammonium salts of alkyl sulfates (alkyl radical: C ₈ -C ₂₀ ), of sulfuric monoesters of ethoxylated alkanols (EO degree: 2 to 50, alkyl radical: C ₈ to C ₂₀ ) and ethoxylated alkylphenols (EO degree: 3 to 50, alkyl radical: C ₄ -C ₂₀ ), of alkylsulfonic acids (alkyl radical C ₈ to C ₂₀ ), of sulfonated mono- and di-C ₆ -C ₈ -alkyldiphenyl ethers, as described in US Pat. No. 4,269,749, and US Pat of alkylarylsulfonic acids (alkyl radical: C ₄ -C ₂₀ ). Further suitable anionic emulsifiers can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular substances, Georg-Thieme-Verlag, Stuttgart, 1961, pp. 192-208.

Suitable nonionic emulsifiers are araliphatic or aliphatic nonionic emulsifiers, for example ethoxylated mono-, di- and trialkylphenols (EO degree: 3 to 50, alkyl radical: C ₄ -C ₉ ), ethoxylates of long-chain alcohols (EO degree: 3 to 50, alkyl radical : C ₈ -C ₃₆ ), as well as polyethylene oxide / polypropylene oxide block copolymers. Preferred are ethoxylates of long-chain alkanols (alkyl radical: C ₁₀ -C ₂₂ , average degree of ethoxylation: 3 to 50) and particularly preferably those based on oxo alcohols and native alcohols having a linear or branched C ₁₂ -C ₁₈ -alkyl radical and an ethoxylation degree of 8 until 50.

Of course, the molecular weight of the polymers can be adjusted by adding regulators in a small amount, usually up to 2 wt .-%, based on the polymerizing monomers M. Suitable regulators are, in particular, organic thio compounds, furthermore allyl alcohols and aldehydes. In the preparation of the butadiene-containing polymers of class I are often regulator in an amount of 0.1 to 2 wt .-%, preferably organic thio compounds such as tert-dodecyl mercaptan used.

After completion of the polymerization, the polymer dispersions used are frequently made alkaline prior to their use according to the invention, preferably adjusted to pH values in the range from 7 to 10. For neutralization, ammonia or organic amines can be used, and preferably hydroxides, such as sodium hydroxide, potassium hydroxide or calcium hydroxide can be used.

For the preparation of polymer powders, the aqueous polymer dispersions are subjected in a known manner to a drying process, preferably in the presence of customary drying auxiliaries. The preferred drying method is spray drying. If necessary, the drying aid is used in an amount of 1 to 30 wt .-%, preferably 2 to 20 wt .-%, based on the polymer content of the dispersion to be dried. The spray-drying of the polymer dispersions to be dried is generally carried out as already described for the microcapsule dispersion, often in the presence of a conventional drying aid such as homopolymers and copolymers of vinylpyrrolidone, homo- and copolymers of acrylic acid and / or methacrylic acid with monomers carrying hydroxyl groups, vinylaromatic monomers, Olefins and / or (meth) acrylic acid esters, polyvinyl alcohol and in particular arylsulfonic acid-formaldehyde condensation products and mixtures thereof.

Further, during the drying process, a conventional anticaking agent such as a finely divided inorganic oxide, for example, a finely divided silica or a finely divided silicate, e.g., a finely divided silicate, may be added to the polymer dispersion to be dried. Add talc.

For certain uses of the coarse-particled compositions of the present invention, water-stability of the binder polymers is not necessary, for example, in sealed nonaqueous systems. In such cases, binder polymers are also suitable which are water-soluble or partially water-soluble.

Suitable natural polymeric binders such as starch and cellulose and synthetic polymeric binders. Such binders are, for example, polyvinylpyrrolidone, polyvinyl alcohol or partially hydrolysed polyvinyl acetate having a degree of hydrolysis of at least 60%, as well as copolymers of vinyl acetate with vinylpyrrolidone, furthermore graft polymers of polyvinyl acetate with polyethers, in particular ethylene oxide. Graft polymers of polyvinyl acetate with ethylene oxide have proved to be particularly advantageous. Such graft polymers are described, for example, in EP-A-1 124 541. whose teaching is expressly referred to. Such polymers are also commercially available, eg under the trade names KOLLIDON ^® and Kollicoat ^® from BASF Aktiengesellschaft.

The preparation of the coarse-particle preparation can be carried out by bringing the microcapsules together with the polymeric binder and water in a coarse-particle form, for example granulated or extruded, and then optionally dried. The binder may be added to the microcapsule powder. According to a further embodiment, the binder may already be added as a spraying aid during the spray-drying of the microcapsules. Such preferred binders are those mentioned above for the spray-drying of the microcapsules. They are usually added in an amount of 1 to 10 wt .-% based on the solids content of the microcapsule dispersion. In these cases, the addition of further binder is possible, but not usually necessary. The binders used may also be the organic protective colloids used in the preparation of the microcapsules. An addition of further binders is then generally unnecessary. According to this preferred variant, from 10 to 100% by weight of one or more C 1 -C ₂₄ -alkyl esters of acrylic and / or methacrylic acid (monomers I), from 0 to 80% by weight of a bifunctional or polyfunctional monomer (monomers II ), which is insoluble or sparingly soluble in water and 0 to 90 wt .-% of other monomers (monomer III), in each case based on the total weight of the monomers, the latent heat storage material and the organic protective colloid prepared an oil-in-water emulsion and formed the capsule wall by free radical polymerization, the resulting microcapsule dispersion spray-dried and brought into a coarse-particled form.

The preparation of the preparation can be carried out according to the methods known for agglomerates such as pellets, tablets and granules.

According to the invention granules can be produced by mixer granulation. Mixers are used, which are provided with rigid or rotating inserts (eg Diosna Pharmamischer) and ideally in one operation mix, granulate and dry. The microcapsule powder is built up with the addition of the polymeric binder and optionally water, by the rearrangement movement to granules. These are then dried in a fluidized bed, convection or vacuum dryer and comminuted by screening machines or mills. For example, a vacuum rotary mixing dryer is particularly gentle and dust-free.

According to the invention, the microcapsules are extruded together with the polymeric binder.

The preparation of the coarse-particle preparation is carried out with the addition of water and the polymeric binder. It is possible to meter in the water to the microcapsule and / or binder powder. According to a preferred embodiment, the microcapsule powder is mixed directly with a binder dispersion of the desired water content. The water content is 10-40 wt .-% based on the total mixture. A lower water content usually leads to incomplete mixing of the two components and poor moldability. Higher water contents are possible in principle, above 50 wt .-% water, the mass can no longer be extruded, but deliquesces. Preferably, a water content of 20-35 wt .-% at the discharge point, since in this area, the pellets obtained already have a good strength.

Suitable extruders such as single- or twin-screw extruder and the so-called melt calendering or melt tableting. Twin-screw extruder working on the principle of a mixing unit, which simultaneously transported forward and compressed on a nozzle tool.

According to a preferred embodiment, the product in the feed zone is compressed against the heating zone. In the middle zone of the extruder, the substances are dispersed and possibly degassed. In the end zone of the extruder, the mixture is discharged under pressure through a die tool.

It is extruded in the temperature range of the glass transition temperature of the binder polymer and preferably below the softening or decomposition temperature of the microcapsule wall. The binder polymer should form a film under the processing conditions, i. it should at least partially melt or soften, but without becoming too fluid to get the microcapsule preparation into shape. A suitable temperature range is the range of 25K below to about 50K above the glass transition temperature. The softening area of

Binder polymer, however, can sometimes be significantly lowered by plasticizer or solvent effects, so that in the presence of these substances, a processing up to 50 K below the glass transition temperature is possible. When using volatile plasticizers, it is thus possible to remove them after the shaping process, whereby a greater strength is achieved. Since water is a plasticizer for polar and water-soluble film-forming polymers, consideration of the glass transition temperature of the pure polymer in these cases does not apply.

The nozzle tool of the extruder may consist of one or more hole nozzles or a flat nozzle as desired or may have a more complex shape, for example tubular. In accordance with the invention, nozzles are selected with which particles are obtained whose ratio of surface to volume obeys the following relation:

Ij surface yVoϊumen Preferred nozzles have for example a cross or Stemform, for example, 3-, 4-, 5- or 6-pronged on.

According to a preferred variant, the temperatures in the extruder are 40 to 120 ^° C. It is possible that a constant temperature prevails. It is also possible that along the transport direction of the microcapsule / binder mixture, a temperature gradient of 40 to 12O ⁰ C prevails. Any gradations are possible with the gradient from continuous to stepwise. The agglomeration at these temperatures has the advantage that some of the water already evaporates during the mixing and / or compression process.

Optionally, lubricants such as stearic acid are added for extrusion. Other additives of the coarse-particle microcapsule preparation may be: dyes, pigments, fragrances, antistatic agents, hydrophilizing agents and preferably graphite, in particular expanded graphite.

According to a preferred embodiment, the preparation contains from 2 to 20% by weight of graphite, based on the total weight of the coarse-particle preparation.

The production of expanded graphite and expanded graphite products is known from US-A 3 404 061. For the production of expanded graphite, graphite intercalation compounds or graphite salts, e.g. Graphite hydrogen sulfate or graphite nitrate, shock-heated. The resulting so-called graphite expander consists of worm or accordion-shaped aggregates.

By compressing this Graphitexpandats under pressure self-supporting graphite sheets or plates can be prepared without binder additive. If such compacted or "pre-compressed" graphite expandate is comminuted by means of cutting, impact and / or jet mills, then a powder or chaff of precompacted graphite expandate is obtained, depending on the degree of comminution. These powders can be finely distributed and homogeneously mixed into molding compounds. Alternatively, graphite expandate may also be used directly, i. without prior compaction, are comminuted to a powder which can be mixed into molding compounds.

Compressed graphite expanded powder or chippings can be re-expanded if needed for further use. Such a process is described in US-A 5,882,570. In this way one obtains a so-called reexpandiertes graphite powder (Reexpandat).

Hereinafter, the term "expanded graphite" is used collectively for (i) graphite expandate, (ii) powder obtained by crushing compressed graphite expandate, (iii) powder obtained by comminuting graphite expandate, and (iv) by re-expanding crushed compacted matter Graphite expandate made Reexpandat. All forms (i) to (iv) of the expanded graphite are suitable additives of the coarse microcapsule preparation. It has

Graphite expandate has a bulk density of 2 to 20 g / l, the shredded graphite expanate has a bulk density of 20 to 150 g / l, the crushed compacted graphite expander has a bulk density of 60 to 200 g / l, and the reclaimed compacted graphite expandate has a bulk density of 20 to 150 g / l.

With expanded graphite having an average particle size of about 5 μm, the BET specific surface area is typically between 25 and 40 m ² / g. As the diameter of the particles increases, the BET surface area of the expanded graphite decreases but remains at a relatively high level. Thus, expanded graphite with an average particle size of 5 mm still has a BET surface area of more than 10 m ² / g. For the production of the particles according to the invention, expanded graphite with average particle sizes in the range from 5 μm to 5 mm is suitable. Preference is given to expanded graphite having an average particle size in the range from 5 μm to 5 mm, particularly preferably in the range from 50 μm to 1 mm.

The microcapsule preparations according to the invention have sealed the latent heat storage material, so that no emissions to the ambient air can be detected. This allows their use not only in closed systems, but also in open systems.

The coarse-particle microcapsule preparations are outstandingly suitable for use in building materials as well as storage material in heat exchangers. They show good hardness and are abrasion resistant. Its coarse-grained structure allows a freely selectable storage geometry, for example, fillings for floor coverings, chemical reactors or columns, as well as in flow-through applications such as heat exchangers in solar systems, heaters in particular warm air heating and centralized and decentralized ventilation.

Due to the favorable ratios of surface to interstices of the particles with each other, a large heat transfer is possible, which can be dissipated by the good flow properties of any support material such as air or water quickly. Based on the volume of the preparation, the coarse-particled microcapsules have a very high storage capacity and thus have a very high efficiency. Thus, they have a small footprint as well as a lower storage weight with the same storage capacity compared to conventional heat storage.

In addition, the coarse-particle microcapsule preparations according to the invention can advantageously be processed together with mineral or silicate binders. Suitable mineral binders are well known. It is finely divided inorganic substances such as lime, gypsum, clay, loam and cement, which are converted by mixing with water in their ready-to-use form and solidify during drying as a function of time, optionally at elevated temperature. The coarse-particle microcapsule preparations according to the invention are converted into the ready-to-use shaped body together with the mineral binder, water, additives such as gravel, sand, glass or mineral fibers and, if appropriate, auxiliaries. The following examples are intended to explain the invention in more detail.

A microcapsule powder was used as obtained according to Example 1 of DE 101 63 162 and subsequent spray drying. The microcapsules had a mean diameter of 7.8 microns.

Example (not according to the invention)

3000 g of the above-described microcapsule powder (mp 28 ⁰ C) were in a

Diosna mixer type V 50 slowly mixed with 287 g of a 55 wt.%, Aqueous styrene-acrylonitrile dispersion (see material B in Example 5) and 623 g of water. The moistened mass was mixed for 6 minutes by switching on the chopper (stage 1), so that the amount of liquid was evenly distributed. This mass was then extruded in an Alexanderwerk laboratory granulator type RSA with a 3.0 mm mesh screen. The granules were then dried on trays. Dry extrudates with a diameter of about 3 mm and a length of 4 mm were obtained, which were hard and resistant to abrasion.

Comparative example

Machine: tightly intermeshing co-rotating twin screw extruder type FTS16mm, discharge nozzle orifice nozzle diameter of 3 mm, 5 heating zones from the entry opening to the discharge nozzle, Zone 1 to 4 heated to 75 ° C, Zone 5 heated to 85 ⁰ C. The extruder screw used is up to an element (return element) approximately in the middle of conventional conveyor elements with which a mixing is ensured by a strong shear field in the gusset area. The total throughput is 775 g / h, the screw speed 150 rpm. The pressure build-up in the screw ensures a continuous discharge of the wetted latent heat storage powder.

Materials:

A) spray-dried PMMA microcapsule powder according to DE 197 49 731 with a core of n-octadecane, consisting of 87% by weight of core, 10% by weight of crosslinked PMMA

Wall (PMMA = polymethyl methacrylate) and 3% dispersant polyvinyl alcohol.

B) 55% by weight, aqueous polymer dispersion of a polymer of 88% by weight of styrene, 10% by weight of acrylonitrile and 2% by weight of acrylic acid, number average molecular weight M _n : 8000, volume-average molecular weight M _w : 45 000, Glass transition temperature Tg: 105 ^° C.

In a vessel, 92 g of the dispersion B), 183 g of water and 500 g of microcapsule powder A) were mixed and added to the hopper of the extruder. This amount of material is completely absorbed and processed within an hour. The head temperature of the extruder reaches 91 ^° C. after a few minutes. At this temperature, the material is conveyed homogeneously and evenly out of the nozzle and through an anhydrous dry discharge in granular form of about 3 mm width and 5 mm length obtained. The theoretical binder content in the granules is 9.2 wt .-%; the paraffin content in the final product is 79%. The granules were then dried in a stream of hot air. The granules can be broken with some effort with the fingers, but is stable when shaking the granules. The granules are stable even after several days of storage under water without dissolution phenomena.

The pore area measured by mercury porosimetry according to DIN 66133 is 28.1 m ² / g.

example 1

The extruder test set-up of the comparative example was adopted with the difference that a star-shaped discharge nozzle (analogous to FIG. 10B) was used (4 × 3 mm profile nozzle).

Materials:

A) Spray-dried PMMA microcapsule powder with a core of n-octadecane

B) B) 55% by weight, aqueous polymer dispersion of a polymer of 88% by weight of styrene, 10% by weight of acrylonitrile and 2% by weight of acrylic acid, number average molecular weight M _n : 8000, volume average molecular weight M w: 45,000 , Glass transition temperature Tg: 105 ⁰ C.

900 g / h of dispersion B), 300 g / h of water and 6500 g of microcapsule powder A) were mixed in a vessel and placed in the hopper of the extruder. This amount of material was completely absorbed and processed in the course of one hour. The head temperature of the extruder reached after a few minutes 55 ⁰ C. With this temperature, the material was conveyed homogeneously and evenly from the nozzle and obtained by an anhydrous Trockenabschlag granules of 4 mm in length and 3 mm in total diameter. The edges of the granules are rounded. The theoretical binder content in the granules is 4.4% by weight. The granules were then dried in a stream of hot air.

The pore area measured by mercury porosimetry acc. DIN 66133 is 39.6 m ² / g.

Claims

claims

1. Coarse-particle microcapsule preparation comprising one or more microencapsulated latent heat storage materials and one or more polymeric binders, wherein the ratio of surface area to volume of the particles obeys the following relation:

^ surface

> 2.5.

\ jVolumen

2. Coarse particulate microcapsule preparation according to claim 1, wherein 90 wt .-% of the particles are greater than 500 microns.

3. Coarse-particled microcapsule preparation according to claim 1 or 2, wherein the binder content calculated as a solid 1 - 40 wt .-% based on the total weight of the coarse-particled microcapsule preparation.

4. coarse microcapsule preparation according to one of claims 1 to 3, wherein the latent heat storage material is a lipophilic substance having a solid / liquid phase transition in the temperature range from -20 to 120 ⁰ C.

5. Coarse particle microcapsule preparation according to any one of claims 1 to 4, wherein the latent heat storage material is an aliphatic hydrocarbon compound.

6. coarse microcapsule preparation according to one of claims 1 to 5, wherein the capsule wall is a thermosetting polymer.

7. coarse microcapsule preparation according to one of claims 1 to 6, wherein the capsule wall is constructed from

10 to 100 wt .-% of one or more CrC ₂₄ alkyl esters of acrylic and / or

Methacrylic acid (monomers I),

0 to 80% by weight of a bifunctional or polyfunctional monomer (monomer II) which is insoluble or sparingly soluble in water and 0 to 90% by weight of other monomers (monomer III)

in each case based on the total weight of the monomers.

A coarse particulate microcapsule formulation according to any one of claims 1 to 7, wherein the binder polymer has film-forming properties under processing conditions.

9. coarse microcapsule preparation according to any one of claims 1 to 8, wherein the binder polymer has a glass transition temperature of -60 to +150 ⁰ C.

10. The coarse-particle microcapsule preparation according to any one of claims 1 to 9, wherein the binder polymer is built up from one or more ethylenically unsaturated monomers M by emulsion polymerization.

11. Coarse particle microcapsule preparation according to any one of claims 1 to 10, wherein the binder polymer is a homopolymer of vinyl esters of aliphatic carboxylic acids or a copolymer of vinyl esters of aliphatic carboxylic acids with olefins and / or alkyl (meth) acrylates.

A coarse microcapsule preparation according to any one of claims 1 to 11, wherein the binder polymer is a copolymer of styrene with acrylonitrile.

13. Coarse-particle microcapsule preparation according to one of claims 1 to 12, wherein the coarse-particulate preparation contains 2-20 wt .-% graphite based on the total weight of the preparation.

The coarse particulate microcapsule formulation of claim 13, wherein the graphite is expanded graphite.

15. A process for the preparation of coarse microcapsule preparations according to claims 1 to 14, characterized in that one brings the microcapsules together with the polymeric binder and water in a coarse-particled form and then optionally dried.

16. A process for the preparation of coarse microcapsule preparations according to claim 15, characterized in that extruding the microcapsules together with the polymeric binder dispersion at temperatures in the range 25 K below to 50 K above the glass transition temperature of the binder polymer and then optionally dried.

17. A process for the preparation of coarse microcapsule preparations according to claim 16, characterized in that extruding at temperatures in the range of 60 to 11O ⁰ C.

18. A process for the preparation of coarse microcapsule preparations according to claim 15, characterized in that extruded by a cross or Stemform.

19. Use of the coarse microcapsule preparation according to claim 1 in heat exchangers.

20. Use of the coarse microcapsule preparation according to claim 1 in building materials.