EP2483491A1

EP2483491A1 - Gypsum wallboard containing micro-encapsulated latent heat accumulator materials

Info

Publication number: EP2483491A1
Application number: EP10763653A
Authority: EP
Inventors: Hans Willax; Britta Katz; Marc Rudolf Jung; Stephan Altmann; Ekkehard Jahns
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2009-10-02
Filing date: 2010-09-28
Publication date: 2012-08-08
Also published as: KR20120099660A; US20120196116A1; CN102639796A; WO2011039177A1; JP6120930B2; JP2016055649A; CN102639796B; BR112012007384A2; JP2013506774A; RU2012117411A

Abstract

The present invention relates to a gypsum wallboard, comprising two cover layers and a gypsum core, wherein the gypsum core contains micro-capsules having a lipophilic capsule core and a capsule wall composed of 30 to 100% by weight, relative to the total weight of the monomers, of one or more monomers (monomers I) selected from the group consisting of C₁-C₂₄-alkyl esters of acrylic and methacrylic acid, acrylic acid, methacrylic acid, and maleic acid, 0 to 70% by weight, relative to the total weight of the monomers, of one or more monomers comprising at least two non-conjugated ethylene double bonds (monomers II), which are not soluble or hardly soluble in water, and 0 to 40% by weight, relative to the total weight of the monomers, of one or more other monomers (monomers III), and at least one polymer P, which has a glass transition temperature T_g of -60 to 160°C. The invention further relates to a method for producing same.

Description

The present invention relates to a plasterboard comprising two cover layers and a gypsum core, wherein the gypsum core contains microcapsules whose capsule core is a lipophilic substance and whose capsule wall is a polymer based on acrylic and / or methacrylic acid or their esters, and a process for their preparation.

There have been many developments in the field of microencapsulated latent heat storage in recent years. Applications range from packaging materials, textiles, heat transfer fluids to building materials such as plasterboard. The operation of the latent heat storage, often referred to as PCM (phase change material), based on the occurring during the solid / liquid phase transition transformation enthalpy, which means an energy intake or energy release to the environment. They can thus be used for temperature maintenance in a defined temperature range. Thus, microencapsulated latent heat storage containing plasterboard allow passive air conditioning of rooms.

Depending on the field of application, different requirements are placed on the size and tightness of the microcapsules. WO 2006/018130 describes the production of pellets for fillings and for flow-through applications such as heat exchangers. The pellets are prepared by extrusion of a mixture of microcapsules and

obtained film-forming polymers.

In construction applications, on the other hand, the focus is on microcapsule powders. Thus, DE-A-101 39 171 and EP 1 291 475 teach the use of microencapsulated latent heat storage materials in gypsum plasterboards. The microcapsule walls are constructed by polymerizing methyl methacrylate and butanediol diacrylate in the presence of inorganic solid particles as a protective colloid.

In many cases, organic waxes are used as latent heat storage materials which melt when the phase transition is exceeded. If such microcapsules are used in porous building materials such as gypsum, it can be observed in capsules with insufficient tightness over a longer period of time, a low leakage of waxes. However, such fumes are undesirable, especially indoors, so that the present invention is based on lower-emission gypsum boards.

One approach to this problem is the development of microcapsules whose walls have a higher density. Thus, WO 2008/046839 teaches microcapsules with an additional polyelectrolyte coating, which increased the tightness of the capsule wall.

Furthermore, the earlier European application 09165134.9 describes microcapsules with walls composed of methyl methacrylate and pentaerythritol tetraacrylate. With this new wall polymer, an improved evaporation rate in the temperature range of 15 to 105 ° C could be achieved.

However, further solutions should be sought to reduce the emissions of the entire system of plasterboard / microcapsules. It was therefore an object of the present invention to provide plasterboards comprising microencapsulated latent heat storage materials which exhibit a low emission of latent heat storage material even over a relatively long period of time. Accordingly, a gypsum board comprising two cover layers and a

Gypsum core found, the gypsum core containing microcapsules with a lipophilic capsule core and a capsule wall constructed by polymerization of

From 30 to 100% by weight, based on the total weight of the monomers, of one or more monomers (monomers I) selected from C 1 -C 24 -alkyl esters of acrylic and methacrylic acid, acrylic acid, methacrylic acid and maleic acid,

0 to 70 wt .-% based on the total weight of the monomers, one or more monomers having at least two non-conjugated ethylenic double bonds (monomers II), which is insoluble or sparingly soluble in water, and

0 to 40 wt .-% based on the total weight of the monomers, one or more other monomers (monomers III), and at least one polymer P containing a glass transition temperature T _g in the range of -60 to 160 ° C, preferably in the range of 60 to 100 ° C, has. Furthermore, the application relates to a method for producing the plasterboard.

Furthermore, the application relates to a microcapsule powder which is obtained by spray-drying an aqueous mixture containing the abovementioned microcapsules and the polymer P and a process for its preparation.

The microcapsules according to the invention contained in the gypsum core comprise a lipophilic capsule core and a capsule wall made of polymer. The capsule core consists predominantly, more than 95% by weight, of lipophilic substance. The average particle size of the capsules (Z means by means of light scattering) is 1 to 50 μηη. According to a preferred embodiment, the average particle size of the capsules is 1 to 5 15 μηι, preferably 4 to 10 μηι. In this case, preferably 90% of the particles have a particle size of less than twice the average particle size.

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.

The polymers of the capsule wall generally contain at least 30% by weight, preferably at least 50% by weight and in a particularly preferred form at least 60% by weight and generally at most 100% by weight, preferably at most 90% by weight .-% and in a particularly preferred form at most 80 wt .-% of one or more monomers (monomers I) selected from Ci-C24 alkyl esters of acrylic and methacrylic acid, acrylic acid, methacrylic acid and maleic acid copolymerized, based on the total weight of the monomers. Furthermore, the polymers of the capsule wall may preferably at least 10 wt .-%, preferably at least 15 wt .-%, preferably at least 20 wt .-% and generally at most 70 wt .-%, preferably at most 50 wt .-%, and more preferably Form at most 30 wt .-% of one or more monomers having at least two non-conjugated ethylenic double bonds (monomers II), which is insoluble in water or sparingly soluble polymerized, based on the total weight of the monomers.

In addition, the polymers may contain up to 40% by weight, preferably up to 30% by weight, in particular up to 10% by weight, particularly preferably 1 to 5% by weight, of one or more monounsaturated, non-ionizable monomers (Monomer III), which are different from the monomers I, incorporated in copolymerized form, based on the total weight of the monomers.

Preferably, the capsule wall is composed only of monomers of groups I and II.

Suitable monomers I are C 1 -C 24 -alkyl esters of acrylic and / or methacrylic acid, acrylic acid, methacrylic acid and maleic acid. Preferred monomers I are methyl, ethyl, n-propyl and n-butyl acrylate and the corresponding methacrylates. Particular preference is given to isopropyl, isobutyl, sec-butyl and tert-butyl acrylate and isopropyl, isobutyl, sec-butyl and tert-butyl methacrylate. Generally, the methacrylates are preferred.

Furthermore, one or more monomers having at least two nonconjugated ethylenic double bonds (monomers II) can be copolymerized with the one or more monomers I. Suitable monomers II are not soluble or sparingly soluble in water, but preferably have good to limited solubility in the lipophilic substance. Low solubility is to be understood as meaning a solubility of less than 60 g / l at 20 ° C. At least two double bonds means that the monomers in usually have two, three, four or five ethylenic double bonds, preferably vinyl or vinylidene groups. They cause a crosslinking of the capsule wall during the polymerization. One or more monomers having two non-conjugated double bonds and / or one or more monomers having more than two non-conjugated double bonds may be copolymerized.

Suitable monomers having two non-conjugated ethylenic double bonds are divinylbenzene and divinylcyclohexane. Preferred are the diesters of diols with acrylic acid or methacrylic acid, furthermore the diallyl and divinyl ethers of these diols. Examples which may be mentioned are ethanediol diacrylate, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, diethylene glycol diacrylate, dipropylene glycol diacrylate, methallyl methacrylamide, allyl acrylate and allyl methacrylate. Particular preference is given to propanediol, butanediol, pentanediol and hexanediol diacrylate and the corresponding methacrylates. Preferred monomers having more than two non-conjugated ethylenic double bonds are the polyesters of polyols with acrylic acid and / or methacrylic acid, furthermore the polyallyl and polyvinyl ethers of these polyols. Preference is given to monomers having three and / or four free-radically polymerizable double bonds. Preference is given to trimethylolpropane triacrylate and methacrylate, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, pentaerythritol triacrylate and pentaerythritol tetraacrylate and their technical mixtures.

Other monomers (monomers I II) other than monomers I and II are monounsaturated monomers such as vinyl acetate, vinyl propionate, vinylpyridine and styrene or α-methylstyrene, itaconic acid, vinylphosphonic acid, maleic anhydride, 2-hydroxyethyl acrylate and methacrylate, acrylamido 2-methylpropanesulfonic acid, methacrylonitrile, acrylonitrile, methacrylamide, N-vinylpyrrolidone, N-methylolacrylamide, N-methylolmethacrylamide, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate. Preference is given to monounsaturated, non-ionizable monomers, such as vinyl acetate, vinyl propionate, vinylpyridine and styrene or α-methylstyrene.

Preferably, microcapsules are used whose capsule wall is constructed from

From 50 to 90% by weight, based on the total weight of the monomers, of one or more monomers (monomers I) selected from C 1 -C 24 -alkyl esters of acrylic and methacrylic acid, acrylic acid, methacrylic acid and maleic acid,

10 to 50 wt .-% based on the total weight of the monomers, one or more monomers having more than two non-conjugated ethylenic double bonds (monomers I I), and

0 to 30 wt .-% based on the total weight of the monomers, one or more other monomers (monomers II I). The microcapsules used according to the invention can be prepared by a so-called in situ polymerization. The principle of microcapsule formation is based on the monomers, free radical initiator, protective colloid and the lipophilic substance to be encapsulated, producing an oil-in-water emulsion in which the monomers and the lipophilic substance are in the form of a disperse phase. According to one embodiment, it is possible to add the radical initiator only after the dispersion. Subsequently, the radical polymerization of the monomers is initiated by heating and optionally controlled by further increase in temperature, the resulting polymers forming the capsule wall which encloses the lipophilic substance. This general principle is described, for example, in DE-A-10 139 171, whose contents are expressly incorporated by reference.

In general, the microcapsules are prepared in the presence of at least one organic and / or inorganic protective colloid. Both organic and inorganic protective colloids may be ionic or neutral. Protective colloids can be used both individually and in mixtures of several identically or differently charged protective colloids. The microcapsules are preferably prepared in the presence of an inorganic protective colloid, in particular in combination with an organic protective colloid.

Organic protective colloids are preferably water-soluble polymers which reduce the surface tension of the water from 73 mN / m to a maximum of 45 to 70 mN / m and thus ensure the formation of closed capsule walls and microcapsules having preferred particle sizes in the range of 0.5 to 50 μm, preferably 0 , 5 to 30 μηη in particular 0.5 to 10 μηη, form.

Organic anionic protective colloids are sodium alginate, polymethacrylic acid and its copolymers, 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 organic anionic protective colloids are naphthalenesulfonic acid and naphthalenesulfonic acid-formaldehyde condensates and above all polyacrylic acids and phenolsulfonic acid-formaldehyde condensates. 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 also methylhydroxypropylcellulose. Polyvinyl alcohol and partially hydrolyzed polyvinyl acetates sold for example as Mowiol ^® grades from Kuraray Specialties Europe (KSE). Preferred organic neutral protective colloids are polyvinyl alcohol and partially hydrolyzed polyvinyl acetates and also methylhydroxy (C 1 -C 4) alkyl cellulose. Suitable methylhydroxy (C 1 -C 4) -alkylcelluloses are, for example, methylhydroxyethylcellulose or methylhydroxypropylcellulose. Particularly preferred is methyl hydroxypropyl cellulose. Such methylhydroxy- (Ci-C4) of the company Hercules / Aqualon are -alkylcelluloses for example available under the tradename Culminal ^®.

Preferably, the microcapsule is prepared by preparing an oil-in-water emulsion comprising as essential components the monomers, free radical initiator, inorganic protective colloid and the lipophilic substance to be encapsulated, and initiating the polymerization. Optionally, controlling the polymerization by increasing the temperature, wherein the resulting polymers form the capsule wall, which encloses the lipophilic substance.

The inorganic protective colloid is preferably inorganic solid particles, so-called Pickering systems. Such a Pickering system can consist of the solid particles alone or additionally of auxiliaries which improve the dispersibility of the particles in water or the wettability of the particles by the lipophilic phase. 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. 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. Particular preference is given to SiO 2 -based silicas, magnesium pyrophosphate and tricalcium phosphate.

Suitable SiO 2 -based protective colloids are finely divided silicas. They can be dispersed as fine, solid particles in water. However, it is also possible to use 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 stable in water. For use of these dispersions as protective colloid, it is advantageous if the pH of the oil-in-water emulsion is adjusted to pH 2 to 7 with an acid. Preferred colloidal dispersions of silica at pH 9.3 have a specific surface area in the range of 70 to 90 m ² / g.

As SiO 2 -based protective colloids, preference is given to highly disperse silicas whose mean particle sizes are in the range from 40 to 150 nm at pH values in the range from 8 to 11. Examples include Levasil® ^® 50/50 (HC Starck), Köstrosol ^® 3550 (CWK Bad Köstritz), and Bindzil ^® mentioned 50/80 (Akzo Nobel Chemicals). Preferably, a combination of an SiO 2 -based protective colloid and a methylhydroxy (Ci-C4) -alkylcellulose is used as described in WO 2009/077525 whose contents are expressly incorporated by reference. In general, the 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. For inorganic protective colloids, preference is given to amounts of from 0.5 to 15% by weight, based on the aqueous phase. Organic protective colloids are preferably used in amounts of from 0.1 to 10% by weight, based on the water phase of the emulsion. The methylhydroxy (C 1 -C 4) -alkylcellulose used according to a preferred embodiment is preferably present in an amount of from 0.5% by weight to

1, 5 wt .-%, in particular from 0.6 wt .-% to 0.8 wt .-% based on the SiO 2 -based protective colloid used. As free-radical initiators for the free-radical polymerization reaction, oil-soluble peroxo and azo compounds generally known to the person skilled in the art, advantageously in amounts of from 0.2 to 5% by weight, based on the weight of the monomers, can be used. Such radical starters are mentioned in WO 2009/077525 whose disclosure is expressly incorporated by reference. Furthermore, it is possible to add to the polymerization known to those skilled controller in conventional amounts such as tert-dodecylmercaptan or Ethylhexylthioglycolat.

In general, the polymerization is carried out at 20 to 100 ° C, preferably at 40 to 95 ° C. Depending on the desired lipophilic substance, the oil-in-water emulsion is to be formed at a temperature at which the core material is liquid / oily. Accordingly, a radical initiator must be selected whose decomposition temperature above this temperature and the polymerization are also carried out 2 to 50 ° C above this temperature, so that optionally selects radical initiator whose decomposition temperature is above the melting point of the lipophilic substance. The reaction times of the polymerization are normally 1 to 10 hours, usually 2 to 5 hours.

Following the actual polymerization reaction at a conversion of 90 to 99% by weight, it is generally advantageous to make the aqueous microcapsule dispersions largely 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 done chemically, as described in WO 99/24525, advantageously by redox-initiated polymerization, as described in DE-A 44 35 423, DE-A 44 19 518 and DE-A 44 35 422.

In order to reduce the residual monomer content beyond that, according to one embodiment, the additional addition of a radical initiator is necessary, which is the beginning of the subsequent Polymerization defined. According to a preferred embodiment, subsequent to the capsule formation, post-polymerization with ammonium, sodium and / or potassium peroxodisulfuric acid as radical initiator is initiated. The salts of peroxydisulphuric acid are water-soluble and start the postpolymerization in and out of the water phase. The salts of peroxodisulfuric acid are expediently used in amounts of from 0.2 to 5% by weight, based on the weight of the monomers. It is possible to dose them at once or over a certain period of time.

If necessary, the post-polymerization can be carried out by adding reducing agents such as sodium bisulfite even at lower temperatures. The addition of reducing agents can further reduce the residual monomer content.

It is possible in this way to produce microcapsules having an average particle size in the range from 0.5 to 100 μm, the particle size being able to be adjusted in a manner known per se by means of the shearing force, the stirring speed and its concentration. Preference is given to microcapsules having an average particle size in the range of 0.5 to 50 μm, preferably 0.5 to 30 μm, in particular 3 to 7 μm (Z agent by means of light scattering).

The lipophilic substance is preferably a latent heat storage material. By definition, latent heat storage materials are substances which have a phase transition in the temperature range in which heat transfer is to be carried out. Preferably, the lipophilic substance has a solid / liquid phase transition in the temperature range from -20 to 120 ° C.

Suitable substances are, for example, aliphatic hydrocarbon compounds, such as saturated or unsaturated C 10 -C 40 -hydrocarbons, which are branched or preferably linear, such as n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-hexadecane, 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, Ci-C4o-alkyl-substituted aromatic hydrocarbons such as dodecylbenzene, tetradecylbenzene, hexadecylbenzene, hexylnaphthalene or decylnaphthalene;

saturated or unsaturated C6-C30 fatty acids such as lauric, stearic, oleic or behenic acid, preferably eutectic mixtures of decanoic acid with e.g. 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 30 fatty amines, such as decylamine, dodecylamine, tetradecylamine or hexadecylamine;

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;

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;

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 lipophilic substances in order to prevent the crystallization delay that 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, latent heat storage materials whose solid / liquid phase transition is in the temperature range from 0 to 60 ° C. are preferred for heat storage in building materials in a moderate climate. For indoor applications, for example, one chooses single substances or mixtures with transformation temperatures of 15 to 30 ° C. 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. The microcapsules can be processed directly as an aqueous microcapsule dispersion or in the form of a powder which can be obtained by spray-drying the microcapsule dispersion. The spray drying of the microcapsule dispersion can be carried out in the usual way. In general, the procedure is such that the inlet temperature of the hot air flow in the range of 100 to 200 ° C, preferably 120 to 160 ° C, and the outlet temperature of the hot air flow in the range of 30 to 90 ° C, preferably 60 to 80 ° C. The spraying of the aqueous polymer dispersion in the stream of hot air can be carried out, for example, by means of single-fluid or multi-fluid 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, spraying aids are added for spray drying in order to facilitate spray drying or to adjust certain powder properties, eg low dust, flowability 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 19629525, DE-A 19629526, DE-A 2214410, DE-A 2445813, EP-A 407889 or EP-A 784449. Advantageous spray aids are, for example, water-soluble polymers of the polyvinyl alcohol type or partially hydrolyzed polyvinyl acetates. Cellulose derivatives such as hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, methylhydroxyethylcellulose and methylhydroxypropylcellulose, starch and starch derivatives, oligosaccharides, sugars and sugar derivatives such as maltodextrin, polyvinylpyrrolidone, copolymers of vinylpyrrolidone, gelatin, preferably polyvinyl alcohol and partially hydrolyzed polyvinyl acetates and also methylhydroxypropylcellulose.

According to the invention, the gypsum core further contains a polymer P which has a glass transition temperature T _g in the range of -60 to 160 ° C. In this case, according to one embodiment, the polymer P can be used in aqueous solution or according to another embodiment in the form of an aqueous dispersion. It is possible to use a polymer P as well as mixtures of two or more polymers P. Aqueous dispersions of the polymers P as 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 frequently in the range from 10 to 1000 nm, often 50 to 500 nm or 100 to 400 nm. According to the invention, those polymers P can be used whose glass transition temperature is -60 to + 160 ° C, usually -60 to + 100 ° C, often -20 to + 100 ° C and often 0 to + 100 ° C. By glass transition temperature ( _Tg ) is meant the glass transition temperature limit to which it tends to increase in molecular weight according to G. Kanig (Kolloid-Zeitschrift & Zeitschrift fur Polymere, Vol. 190, page 1, Equation 1). The glass transition temperature is determined by the DSC method (differential scanning calorimetry, 20 K / min, midpoint measurement, DIN 53 765).

It is possible for a person skilled in the art to prepare polymers with a glass transition temperature in the range from -60 to + 160 ° C. by selective choice of the monomer composition.

According to Fox (see Ullmanns Enzyklopadie der technischen Chemie, 4th Edition, Volume 19, Weinheim (1980), p. 17, 18), the glass transition temperature T _g can be estimated. It applies to the glass transition temperature of weak or uncrosslinked copolymers at high molecular weights in a good approximation: wherein X ¹ , X ² , Xn the mass fractions 1, 2, n and T _g ¹ , T _g ² , T _g ⁿ mean the glass transition temperatures of each of only one of the monomers 1, 2, n constructed polymers in degrees Kelvin. The latter are z. From Ullmann's Encyclopedia of Industrial Chemistry, VCH, 5th Ed. Weinheim, Vol. A 21 (1992) p. 169 or from

J. Brandrup, E.H. Immergut, Polymer Handbook 3rd ed, J. Wiley, New York 1989.

Preference is given to polymers P having a glass transition temperature in the range from -60 to 100 ° C., which are synthesized by free-radical emulsion polymerization of at least one ethylenically unsaturated monomer.

Preferred polymers P are synthesized from ethylenically unsaturated monomers M which generally contain at least 80% by weight, in particular at least 90% by weight, of ethylenically unsaturated monomers A having a water solubility <30 g / l (25 ° C. and 1 bar). include, wherein up to 30 wt .-%, eg 5 to 25 wt .-% of the monomers A by acrylonitrile and / or methacrylonitrile may be replaced. 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.

As a rule, monomers A are simply ethylenically unsaturated or conjugated diolefins. Examples of monomers A are: Esters of an α, β-ethylenically unsaturated C3-C6 monocarboxylic acid or C4-C8 dicarboxylic acid with a Ci-Cio-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 propionate, 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;

Maleic anhydride.

Preferred polymers P are selected from the polymer classes I to VI listed below:

I) Copolymers of styrene with alkyl (acrylates), i. Copolymers which comprise, as monomer A, styrene and at least one C 1 -C 10 -alkyl ester of acrylic acid and, if appropriate, one or more C 1 -C 10 -alkyl esters of methacrylic acid;

II) Copolymers of styrene with butadiene, i. Copolymers containing as monomer A styrene and butadiene and optionally (meth) acrylic esters of

Embedded image C 1 -C 5 -alkanols, acrylonitrile and / or methacrylonitrile in copolymerized form;

III) Homopolymers and copolymers of alkyl (meth) acrylates (pure acrylates), ie homopolymers and copolymers containing in copolymerized form as monomers A at least one Ci-Cio-alkyl esters of acrylic acid and / or a Ci-Cio-alkyl esters of methacrylic acid, in particular Copolymers containing in copolymerized form as monomers A methyl methacrylate, at least one Ci-Cio-alkyl esters of acrylic acid and optionally a C2-Cio-alkyl esters of methacrylic acid; 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 ge - if appropriate, one or more C 2 -C 6 -olefins and / or optionally one or more C 1 -C 10 -alkyl esters of acrylic acid and / or of methacrylic acid polymerized in copolymerized form; V) Copolymers of styrene with acrylonitrile

VI) Copolymers of olefins with maleic anhydride.

Typical C 1 -C 10 -alkyl esters of acrylic acid in the copolymers of the 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 1 -C 10 -ione 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 the monomers A.

Typical copolymers of class II contain as monomers A, in each case based on the total amount of the monomers A, 30 to 85 wt .-%, preferably 40 to

80 wt .-% and particularly preferably 50 to 75 wt .-% styrene and 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 esters of

Ci-Cs 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 Acrylic acid esters of C 1 -C 10 -alkanols, in particular n-butyl acrylate, 2-ethylhexyl acrylate and ethyl acrylate and optionally a methacrylic acid ester of a C 2 -C 10 -alkanol in a total amount of from 20 to 80% by weight and preferably from 30 to 70% by weight in copolymerized form. 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% by weight, preferably 0 to 60% by weight and particularly preferably 0 to 50% by weight of a C 2 -C 6 -olefin, in particular ethylene and optionally one or two further monomers, selected from among (meth) acrylic acid esters of C 1 -C 10 -alkanols in an amount of from 1 to 15% by weight. Among the aforementioned polymers, the polymers of classes IV, V and VI 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 Oligomerisierungsgrade preferably in the range of 2 to 200, for example Monovinyl and monoallyl ethers of oligoethylene glycols and 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 oligalkylene oxide chains, 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, if contained, 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. As monomers B further compounds which have two non-conjugated, ethylenically unsaturated bonds, for example the di- and oligoesters of polyhydric alcohols with α, β-monoethylenically unsaturated C3-Cio 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'-divinylimidazolin-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.

Further, as monomers B are also vinylsilanes, e.g. Vinyltrialkoxysilane suitable. 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. e.g. Encyclopedia of Polymer Science and Engineering, Vol. 8, pp. 659-677, John Wiley & Sons, Inc., 1987; D.C. Blackley, Emulsion Polymerization, pp. 155-465, Applied Science Publishers, Ltd., Essex, 1975; D.C. Blackley, Polymer Latices, 2nd Edition, Vol. 1, pp. 33-415, 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 known to 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 19741 184, US Pat. DE-A 19741 187, DE-A 19805122, DE-A 19828183, DE-A 19839199, DE-A 19840586 and 198471 15], the polymer solids content is adjusted by dilution or concentration to a desired value or the aqueous polymer dispersion further customary Additives such as bactericidal or foam-damping additives added. Frequently, the polymer solids contents of the aqueous polymer dispersions are 30 to 80% by weight, 40 to 70% by weight or 45 to 65% by weight. 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 ^® BASF Aktiengesellschaft, Ludwigshafen, Germany, VINNOFIL ^® and VINNAPAS ^® from. Wacker Chemie GmbH, Burghausen, and RHODIMAX ^® from. Rhodia SA Suitable surface-active substances for the emulsion polymerization are commonly used for the emulsion polymerization used emulsifiers and protective colloids into consideration. Preferred emulsifiers are anionic and nonionic emulsifiers which, unlike 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: C8-C20), of sulfuric monoesters of ethoxylated alkanols (EO degree: 2 to 50, alkyl radical: Cs to C20) and ethoxylated alkylphenols (EO degree: 3 to 50, Alkyl radical: C4-C20), of alkylsulfonic acids (alkyl radical: Cs to C20), of sulfonated mono- and di-C6-C18-alkyldiphenyl ethers, as described in US Pat. No. 4,269,749, and of alkylarylsulfonic acids (alkyl radical: C4-C20 ). 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 grade: 3 to 50, alkyl group: C4-C9), long-chain alcohol ethoxylates (EO grade: 3 to 50, alkyl group: C8-C36), and polyethylene oxide / polypropylene oxide block copolymers. Preferred are ethoxylates of long-chain alkanols (alkyl radical: C10-C22, average degree of ethoxylation: 3 to 50) and particularly preferred are 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, generally up to 2% by weight, 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 before their use according to the invention are often alkaline, preferably on pH values are adjusted in the range of 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 P, the aqueous polymer dispersions are subjected in a known manner to a drying process, preferably in the presence of customary drying auxiliaries. Preferred drying method is the 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, homopolymers and copolymers of acrylic acid and / or methacrylic acid with monomers carrying hydroxyl groups, vinylaromatic monomers, Olefins and / or (meth) acrylic esters, polyvinyl alcohol and in particular arylsulfonic acid-formaldehyde condensation products and mixtures thereof. Further, to the polymer dispersion to be dried during drying, a conventional anticaking agent such as a finely divided inorganic oxide such as a finely divided silica or a finely divided silicate, e.g. Add talc. According to a further preferred embodiment, polymers P are suitable which are water-soluble or partially water-soluble and have a glass transition temperature in the range from 0 to 160 ° C. Partially water-soluble is to be understood as meaning a solubility of> 10 g / l (25 ° C. and 1 bar). Suitable natural polymeric binders such as starch, starch derivatives and cellulose and synthetic polymeric Bindemit- tel. Such binders are, for example, polyvinylpyrrolidone, polyvinyl alcohol or partially hydrolyzed polyvinyl acetate having a degree of hydrolysis of at least 60%, and also 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, to the teaching of which reference is expressly made.

Such polymers are also commercially available, eg under the trade names KOLLIDON ^® and Kollicoat ^® and LUVISKOL ^® of BASF SE. The gypsum slurry is prepared as generally known by continuous addition and mixing of β-hemihydrate calcium sulfate in water with additives. The microcapsules can be processed both as a dispersion, preferably as a powder with the other substances to gypsum pulp. Likewise, the polymer P can be used both as powder ver as well as dispersion or aqueous solution with the other substances are processed to gypsum slurry.

Preferably, the microcapsules and the polymer are previously mixed and used as an aqueous mixture for the production of gypsum board. In this case, according to one embodiment, it is possible to mix the microcapsule powder with an aqueous solution or dispersion of the polymer P before it is mixed with the gypsum slurry. According to a further embodiment, it is possible to mix the aqueous microcapsule dispersion and the polymer P in the form of a powder before the mixture is mixed with the gypsum slurry. According to a preferred embodiment, the aqueous microcapsule dispersion is previously mixed with an aqueous dispersion of the polymer P or an aqueous solution and then mixed with the gypsum slurry.

Preferably, the aqueous mixture of polymer P and microcapsules is spray-dried and the spray-dried polymer-modified microcapsule powder is used to produce the plasterboard. The spray drying is carried out as described above for the microcapsules. Spray dried microcapsules obtained in this way have improved tightness. It is believed that the polymer P is filmed and thus forms an additional layer of polymer around the capsule, which covers the wall partially or completely. Microcapsules obtained by spray-drying a mixture of aqueous polymer dispersion of a polymer P having a glass transition temperature T _g in the range of -60 to 100 ° C and microcapsules are novel.

The present invention therefore also relates to microcapsule powder, preferably having a mean particle size of from 20 to 500 μm, obtainable by spray-drying an aqueous mixture comprising microcapsules with a lipophilic capsule core and a capsule wall

0 to 40 wt .-% based on the total weight of the monomers, one or more other monomers (monomers III) and a polymer P, which has a glass transition temperature T _g in the range of -60 to 100 ° C. Preference is given to polymers P having a glass transition temperature in the range from -60 to 100 ° C., which are synthesized by free-radical emulsion polymerization of at least one ethylenically unsaturated monomer. Preferred polymers P are composed of ethylenically unsaturated monomers M, which are generally at least 80 wt .-%, in particular at least 90 wt .-%, of ethylenically unsaturated monomers A, having a water solubility <30 g / l (25 ° C and 1 bar ), preferably those mentioned above, wherein up to 30% by weight, eg 5 to

25% by weight of the monomers A can be replaced by acrylonitrile and / or methacrylonitrile. In addition, the polymers contain from 0.5 to 20 wt .-% of the monomers A other monomers B, in particular the above.

Preferred polymers P are selected from the polymer classes I to VI listed above, in particular the polymer classes IV, V and VI. Furthermore, the present invention relates to a method for producing these microcapsules by spray drying an aqueous mixture containing microcapsules and an aqueous dispersion of the polymer P.

The proportion of polymer P (solid) is usually 1 to 30 parts by weight, preferably 2 to 20 parts by weight, in particular 5 to 15 parts by weight, in each case based on 100 parts by weight of microcapsule (also calculated as a solid ). The dilution of the intended for spray drying mixture is largely arbitrary. However, it is advantageous to use aqueous mixture having a total solids content of 15 to 45%. The microcapsules are used in amounts of 5 to 50 wt .-% based on gypsum.

The gypsum board according to the invention comprises two cover layers and a gypsum core. Advantageous cover layers are paperboard sheets based on cellulose as well as woven or nonwovens, so-called "nonwovens". Materials for such nonwovens are glass fibers, polymer fibers of z. Polypropylene, polyester, polyamide, polyacrylates, polyacrylonitrile and the like. Particular preference is given to using glass fiber fleece as cover layers. Such structural panels are known for example from US 4,810,569,

US 4,195,110, US 4,394,411, EP 755,903, EP 503,383 and EP 427,063. Preference is gypsum plasterboard with a double-sided cover layer of fiberglass fabric.

In this case, preferably 5 to 40% by weight, in particular 20 to 35% by weight, of microcapsule powder, based on the total weight of the building board, in particular plasterboard (dry substance) are incorporated. The production of plasterboard with microencapsulated latent heat storage materials is well known and in the

EP-A 1 421 243 to which reference is expressly made. They are usually prepared in such a way that aqueous gypsum slurry is discontinuous or preferably continuously between two cover layers, whereby plates are formed. The gypsum slurry is prepared by continuous addition and mixing of β-hemihydrate calcium sulfate in water with additives. The microcapsules can be dosed together with the calcium sulfate, as well as already present as an aqueous dispersion.

As additives, up to 2% by weight, based on the mineral constituents, of the liquefier, retarders and / or accelerators known to the person skilled in the art can generally be used.

The gypsum slurry thus obtained is applied to the cover layer, for example sprayed and covered with the second cover layer. During incipient curing, the building panels are formed in a press into strips of, for example, 1, 2-1, 25 m wide and 9.25, 12.5, 15.0, 18.0 or 25 mm thick. These strips harden within a few minutes and are cut into sheets. At this stage, the plates usually contain one third of their weight as free water. In order to remove the residual water, the plates are subjected to a heat treatment at temperatures up to 250 ° C. For example, tunnel dryers are used.

The resulting plasterboard has a density of 750-950 kg / m ³ .

The plasterboard according to the invention also have good tightness over a longer period of time even at lower temperatures. The following examples are intended to explain the invention in more detail. The percentages in the examples are by weight unless otherwise specified.

The particle size of the microcapsule dispersion was determined with a Malvern Particle Sizer Type 3600E according to a standard measurement method documented in the literature. The D [v, 0,1] value indicates that 10% of the particles have a particle size (by volume) up to this value. Correspondingly, D [v, 0.5] means that 50% of the particles and D [v, 0.9] means that 90% of the particles have a particle size (by volume) less than or equal to this value. The span value results from the quotient of the difference D [v, 0,9] - D [v, 0,1]) and D [v, 0,5]. Preparation of the microcapsule dispersion

Example 1 Water Phase:

680 g of water

1 10 g of a 50% strength by weight silica sol (specific surface area about 80 m ² Ig)

8 g of a 5 wt .-% aqueous solution of methyl hydroxypropyl cellulose having an average molecular weight of 26000 g / mol

2.1 g of a 2.5% strength by weight aqueous sodium nitrite solution

4.0 g of a 20% strength by weight nitric acid solution in water

oil phase

308.0 g of a mixture of substantially linear paraffins having a melting point of about 26 ° C.

123.2 g hexadecane (techn.)

8.8 g of a technical grade paraffin with a melting point of about 65 ° C.

66.0 g of methyl methacrylate

44.0 g pentaerythritol tetraacrylate (technical, Fa. Cytec)

Addition 1

0.92 g of a 75% solution of t-butyl perpivalate in aliphatic. hydrocarbons

Feed 1:

22.0 g of a 5 wt .-% aqueous Na-Peroxodisulfatlösung

30.0 g of WWaasssseerr

The aqueous phase was initially introduced at 40 ° C., into which the molten and homogeneously mixed oil phase was added and dispersed for 40 minutes with a high-speed dissolver stirrer (disk diameter 5 cm) at 3500 rpm. Addition 1 was added. The emulsion was heated to 70 ° C. with stirring with an anchor raker in 60 minutes, heated to 90 ° C. within a further 60 minutes and kept at 90 ° C. for 60 minutes. Feed 1 was metered into the resulting microcapsule dispersion with stirring at 90 ° C. for 90 minutes and then stirred for 2 hours at this temperature. It was then cooled to room temperature and neutralized with aqueous sodium hydroxide solution.

A microcapsule dispersion with a mean particle size of 7.2 μm and a solids content of 43.6% was obtained. General description of the experiments

In each case 100 g of the microcapsule dispersion obtained from Example 1 was mixed with the polymer solutions or polymer dispersions mentioned in Examples AF below. In order to test the tightness of the resulting microcapsule polymer blends, about 2 g each of the obtained mixture was dried at 105 ° C. for two hours to remove any residual water. Then the weight (m ₀ ) was determined. After one hour of heating to 180 ° C, the weight (mi) was determined after cooling. The weight difference (m ₀ - mi) with respect to m ₀ and multiplied by 100 indicates the evaporation rate in%. The smaller the value, the denser the microcapsules.

Example A - Comparative Example - not according to the invention, without polymer

The evaporation rate of the microcapsule dispersion obtained from Example 1 is 67.3%.

Example B

16.8 g of Mowiol ^® -18-88 solution (10 wt.% In water) were mixed according to the general procedure with 100 g of microcapsule dispersion of Example 1.

From the microcapsule / polymer sample the evaporation rate was determined.

The evaporation rate at 180 ° C was 17.9%.

Example C

3.4 g of starch solution (50% strength by weight in water) were mixed according to the general procedure with 100 g of the microcapsule dispersion of Example 1.

From the microcapsule / polymer sample the evaporation rate was determined.

The evaporation rate at 180 ° C was 54.2%.

Example D

6.5 g of a 26% strength by weight aqueous dispersion of an olefin / maleic anhydride copolymer were mixed according to the general procedure with 100 g of the microcapsule dispersion of Example 1.

From the microcapsule / polymer sample the evaporation rate was determined.

The evaporation rate at 180 ° C was 43.1%.

Example E

2.55 g starch solution (50% strength by weight) and 1.6 g of an aqueous dispersion of an olefin / maleic anhydride copolymer (26% strength by weight in water) were prepared according to the general procedure with 100 g microcapsule dispersion of Example 1 mixed.

From the microcapsule / polymer sample the evaporation rate was determined.

The evaporation rate at 180 ° C was 18.3%. Example F

16.8 g of a Mowiol 40-88 solution (10% strength by weight) were mixed according to the general procedure with 100 g of the microcapsule dispersion of Example 1.

From the microcapsule / polymer sample the evaporation rate was determined.

The evaporation rate at 180 ° C was 14.5%.

In the above examples, due to the procedure for sample preparation for determining the evaporation rate, it can not be excluded that the capsules after drying are covered by a macroscopic film of the polymer. In order to examine the tightness of the isolated capsules, a second determination of the evaporation rate was made:

In each case 100 g of the microcapsule dispersion obtained from Example 1 was mixed with the polymer solutions or polymer dispersions mentioned in Examples G-J below. In order to test the tightness of the microcapsule-polymer mixtures obtained, the mixture obtained was diluted to a total solids content of 20% and about 0.5 g of this mixture was added dropwise to about 2 g of sand. From the thus prepared sample, the evaporation rate was determined at 180 ° C. The application to the sand is intended to increase the surface area and separate the capsules so that the measurement result is not influenced by agglomeration and film formation as a layer over the capsules.

Determination of the evaporation rate at 180 ° C. For pretreatment, 2 g of the sand / microcapsule / polymer sample were dried in a metal dish at 105 ° C. for two hours in order to remove any residual water. Then the weight (m ₀ ) was determined. After one hour of heating to 180 ° C, the weight (mi) was determined after cooling. The weight difference (mo - mi) in relation to mo and multiplied by 100 indicates the evaporation rate in%. The smaller the value, the denser the microcapsules.

Example G (not according to the invention)

100 g of the microcapsule dispersion prepared according to Example 1 were treated according to the general procedure without adding polymer.

From the sand / microcapsule sample the evaporation rate was determined.

The evaporation rate at 180 ° C was 41%.

Example H

17.4 g Luviskol ^® K90 - solution (polyvinylpyrrolidone, K value 90, 10 wt .-% strength poly merlösung in water, manufactured by BASF SE) were mixed according to the general procedure with 100 g of microcapsule dispersion of Example 1. Fig.

From the sand / microcapsule / polymer sample the evaporation rate was determined.

The evaporation rate at 180 ° C was 27.4%. Example I

5 g Acronal ^® 290 D - dispersion (50 wt .-% solids, manufactured by BASF SE) were mixed according to the general procedure with 100 g of microcapsule dispersion of Example 1. Fig.

The evaporation rate at 180 ° C was 32.2%.

Example J

4 g of Luviskol VA 64 solution (50% strength by weight polymer solution in water) were mixed according to the general procedure with 100 g of the microcapsule dispersion of Example 1. From the sand / microcapsule / polymer sample the evaporation rate was determined.

The evaporation rate at 180 ° C was 34.4%. The aqueous mixtures of polymer / microcapsules prepared according to Examples B to F or H to J can be incorporated into gypsum pulp in conventional amounts, for example in a mixing ratio of 1: 9 to 5: 5 solid to gypsum hemihydrate and sheeted on a strip mill to process. Example K

1000 g of the microcapsule dispersion as described in Example 1 were mixed with 168 g of Mowiol ^® -18-88 solution (10 wt.% In water) was added and spray dried to a powder, whose average particle size was between 50 and 250 μηη. The resulting powder was stirred into gypsum slurry in a ratio of 30:70 capsule powder to gypsum hemihydrate. From this gypsum mixture was prepared by drying in the oven, a gypsum plate.

Examination of the air by means of a suction cup revealed a paraffin loading of the air, which was by a factor of 4 below a reference plate which was obtained by spray-drying a capsule dispersion from Example 1 without prior addition of further polymers Dispersion was prepared.

Claims

claims

1 . Gypsum board comprising two outer layers and a gypsum core, characterized in that the gypsum core microcapsules with a lipophilic capsule core and a capsule wall constructed from

30 to 100 wt .-% based on the total weight of the monomers, one or more monomers (monomers I) selected from

C 1 -C 24 -alkyl esters of acrylic and methacrylic acid, acrylic acid, methacrylic acid and maleic acid,

0 to 40 wt .-% based on the total weight of the monomers, one or more other monomers (monomers III), and at least one polymer P, which has a glass transition temperature T _g in the range of -60 to 160 ° C contains.

Plasterboard according to claim 1, characterized in that the capsule wall of the microcapsule is constructed from

50 to 90 wt .-% based on the total weight of the monomers, one or more monomers (monomers I) selected from

From 10 to 50% by weight, based on the total weight of the monomers, of one or more monomers having more than two non-conjugated ethylenic double bonds (monomers II), which is described in US Pat

Water is not soluble or difficult to dissolve as well

0 to 30 wt .-% based on the total weight of the monomers, one or more other monomers (monomers III).

Plasterboard according to claim 1 or 2, characterized in that the polymer P has a glass transition temperature in the range of -60 to 100 and is composed of one or more ethylenically unsaturated monomers M by emulsion polymerization.

4. plasterboard according to one of claims 1 to 3, characterized in that the polymer P 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.

5. plasterboard according to one of claims 1 to 4, characterized in that the binder polymer is a copolymer of styrene with acrylonitrile.

Plasterboard according to one of claims 1 to 4, characterized in that the polymer P is water-soluble or partially water-soluble and has a glass transition temperature in the range of 0 to 160 ° C.

Plasterboard according to one of claims 1 to 4, characterized in that an aqueous mixture of microcapsules and the polymer P is used to produce the gypsum board.

Plasterboard according to one of Claims 1 to 7, characterized in that a microcapsule powder which is obtained by spray-drying an aqueous mixture of microcapsules and the polymer P is used to produce the plasterboard.

Plasterboard according to one of claims 1 to 8, characterized in that the cover layers are selected from cardboard sheets based on cellulose, fabric or non-woven.

Plasterboard according to one of claims 1 to 9, characterized in that 1 to 30 parts by weight of polymer P (solid) based on 100 parts by weight are used.

A process for producing a plasterboard according to claims 1 to 10, characterized in that applying a gypsum slurry containing microcapsules and polymer P on a cover layer, covering with a second cover layer and cuts after setting and drying, preferably at temperatures in the range of 50 to 250 ° C, in particular 50 to 150 ° C dried. ,

Microcapsule powder obtainable by spray-drying an aqueous mixture comprising microcapsules with a lipophilic capsule core and a capsule wall constructed from From 30 to 100% by weight, based on the total weight of the monomers, of one or more monomers (monomers I) selected from C 1 -C 24 -alkyl esters of acrylic and methacrylic acid, acrylic acid, methacrylic acid and maleic acid,

0 to 40 wt .-% based on the total weight of the monomers, one or more other monomers (monomers III) and polymer P, which has a glass transition temperature T _g in the range of -60 to 100 ° C. 13. Process for the preparation of microcapsules according to claim 12, characterized in that an aqueous mixture containing microcapsules and polymer P is spray-dried.