DE102004005912A1 - Sound-absorbing concrete block with high thermal storage capacity, e.g. for building walls or for use as surface cladding, contains microcapsules with a polymeric capsule wall and a core of latent heat storage material - Google Patents

Abstract

Sound-absorbing formed products made of concrete with a no-fines texture comprising pores with an average diameter of 0.2-4 mm, in which the concrete contains microcapsules with a polymer (A) as the capsule wall and a core consisting mainly of latent heat storage material (B).

Description

The The present invention relates to a sound absorbing molded body porous concrete whose pores have an average diameter from 0.2-4 mm.

In buildings with modern architecture, such as office buildings, are often big glass surfaces in combination with a light interior design. Such large and smooth view concrete surfaces, glass surfaces and lead steel elements to an echoing room acoustics. This problem is encountered with sound-absorbing components or components. Such components can consist of haufwerksporigem concrete, so an open porous lightweight concrete. Lightweight concrete elements are manufactured by adding aggregates, Cement and water mixed at high speed, in shape filled and by strong shaking and pressure compacted.

A further problematic of such buildings is the heat input. The main heat entry happens through the big ones Glass surfaces. The heat is in the building interior captured. building their construction of steel and concrete solely on static aspects based, have only a small building mass. At the tempering Effect of a building However, this is crucial, with both outside and outside also interior walls have an influence. A heavy building can buffer temperature peaks by its mass. The mass of In the summer, building materials store the incoming heat during the day and keep it that way the internal temperature constant. In the cooler night, the stored Heat again to the outside air issued. For a pleasant indoor climate even in summer without active To achieve air conditioning, so thermal mass of the building is essential.

A such big ones However, thermal mass is lacking in modern office buildings due to their construction.

Lightweight concrete blocks made of processed natural pumice show in accordance with OS 36 27 452 good thermal insulation and good soundproofing. Good insulating effect is only so long advantageous, as no large heat input from the outside, as with big ones Window fronts happens, takes place. To a smart tempering To have stone are just the opposite, namely high thermal conductivity value or k values related to the stone density required.

In The last years are as a new combination of materials in building materials Latent heat storage been examined. Their operation is based on the solid / liquid phase transition occurring conversion enthalpy, the energy consumption or Energy delivery to the environment means. You can thus keep the temperature constant be used in a specified temperature range. Because the Latent heat storage materials also liquid depending on the temperature can exist they are not processed directly with building materials, because emissions to the room air and the separation of the building material would be to be feared.

The EP-A-1 029 018 teaches the use of microcapsules having a capsule wall from a highly crosslinked methacrylic acid ester polymer and a latent heat storage core in binding materials such as concrete or plaster. Since the capsule walls only have a thickness in the range of 5 to 500 nm, but they are very pressure sensitive, an effect of using them in carbonless papers is being used. That limits however, their use.

The DE 101 07 145 teaches a sound-absorbing acoustic ceiling made of building boards made of porous particles, such as expanded clay, bonded by means of a binder. In the pores of the expanded clay latent heat storage materials are bound. Here, however, the above-mentioned problem of emissions arises.

task The present invention is sound-absorbing moldings, the high heat storage capacity show relative to the stone density.

These Task is characterized by a sound-absorbing molded body loose-pile concrete, whose pores have an average diameter of 0.2-4 mm, the concrete Microcapsules with a polymer as capsule wall and a capsule core, consisting predominantly from latent heat storage materials, contains.

The microcapsules contained in the moldings of the invention are particles having a capsule core consisting predominantly, to more than 95 wt .-%, of latent heat storage materials and a polymer as a 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 .mu.m, preferably 1 to 80 .mu.m in particular 1 to 50 microns. The weight ratio of capsule core to capsule wall is generally from 50:50 to 95: 5. Preferred is a core / Vand ratio of 70:30 to 90:10.

Latent heat storage materials are by definition substances, in the temperature range in which a heat transfer is made should, a phase transition exhibit. Preferably, the latent heat storage materials have a solid / liquid Phase transition in the temperature range from -20 to 120 ° C. Usually acts it is the latent heat storage to organic, preferably lipophilic substances.

• – aliphatische Kohlenwasserstoffverbindungen wie gesättigte oder ungesättigte C₁₀-C₄₀-Kohlenwasserstoffe, die verzweigt oder bevorzugt linear sind, z.B. wie n-Tetradecan, n-Pentadecan, n-Hexadecan, n-Heptadecan, n-Octadecan, n-Nonadecan, n-Eicosan, n-Heneicosan, n-Docosan, n-Tricosan, n-Tetracosan, n-Pentacosan, n-Hexacosan, n-Heptacosan, n-Octacosan sowie cyclische Kohlenwasserstoffe, z.B. Cyclohexan, Cyclooctan, Cyclodecan;
• – aromatische Kohlenwasserstoffverbindungen wie Benzol, Naphthalin, Biphenyl, o- oder n-Terphenyl, C₁-C₄₀-alkylsubstituierte aromatische Kohlenwasserstoffe wie Dodecylbenzol, Tetradecylbenzol, Hexadecylbenzol, Hexylnaphthalin oder Decylnaphthalin;
• – gesättigte oder ungesättigte C₆-C₃₀-Fettsäuren wie Laurin-, Stearin-, Öl- oder Behensäure, bevorzugt eutektische Gemische aus Decansäure mit z.B. Myristin-, Palmitin- oder Laurinsäure;
• – Fettalkohole wie Lauryl-, Stearyl-, Oleyl-, Myristyl-, Cetylalkohol, Gemische wie Kokosfettalkohol sowie die sogenannten Oxoalkohole, die man durch Hydroformylierung von α-Olefinen und weiteren Umsetzungen erhält;
• – C₆-C₃₀-Fettamine, wie Decylamin, Dodecylamin, Tetradecylamin oder Hexadecylamin;
• – Ester wie C₁-C₁₀-Alkylester von Fettsäuren wie Propylpalmitat, Methylstearat oder Methylpalmitat sowie bevorzugt ihre eutektischen Gemische oder Methylcinnamat;
• – natürliche und synthetische Wachse wie Montansäurewachse, Montanesterwachse, Carnaubawachs, Polyethylenwachs, oxidierte Wachse, Polyvinyletherwachs, Ethylenvinylacetatwachs oder Hartwachse nach Fischer-Tropsch-Verfahren;
• – halogenierte Kohlenwasserstoffe wie Chlorparaffin, Bromoctadecan, Brompentadecan, Bromnonadecan, Bromeicosan, Bromdocosan.

Suitable substances may be mentioned by way of example:

• Aliphatic hydrocarbon compounds, such as saturated or unsaturated C ₁₀ -C ₄₀ -hydrocarbons, which are branched or preferably linear, 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 eutectic 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 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.

Farther Mixtures of these substances are suitable as long as it is not too a melting point depression outside the desired Area comes in, or the heat of fusion of the mixture for a meaningful Application becomes too low.

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

Farther It may be advantageous to the capsule core-forming substances in soluble in them Add compounds, so in part to the non-polar substances to prevent occurring freezing point depression. Advantageous As described in US Pat. No. 5,456,852, compounds are used with a 20 to 120 ° C higher Melting point as 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 in Quantities of 0.1 to 10 wt .-% based on the capsule core added.

ever according to the temperature range in which the heat accumulators are desired, the lipophilic substances are chosen. For example, used one for one heat storage in building materials in temperate climates prefers lipophilic substances whose solid / liquid phase transition in the temperature range from 0 to 60 ° C lies. So chooses you usually for outdoor applications Single substances or mixtures with transformation temperatures from 0 to 25 ° C and for interior applications from 15 to 30 ° C.

preferred Latent heat storage materials For example, aliphatic hydrocarbons particularly preferred are those listed above enumerated by way of example. In particular, aliphatic hydrocarbons having 16, 17 or 18 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. For example, it is possible to use the latent heat storage materials according to the methods described in GB-A 870476, US 2,800,457 . US 3,041,289 described in gelatin with to encapsulate their polymers.

preferred Wall materials, since they are very resistant to aging, are thermosetting polymers. Under thermosetting wall materials are to be understood, the not soften due to the high degree of cross-linking, but rather decompose at high temperatures. Suitable thermosetting wall materials are, for example, formaldehyde resins, polyureas and polyurethanes and highly crosslinked methacrylic acid ester polymers.

• – Triazinen wie Melamin
• – Carbamiden wie Harnstoff
• – Phenolen wie Phenol, m-Kresol und Resorcin
• – Amino- und Amidoverbindungen wie Anilin, p-Toluolsulfonamid, Ethylenharnstoff und Guanidin,

oder ihren Mischungen.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.

Preferred formaldehyde resins are urea-formaldehyde resins, urea-resorcin-formaldehyde resins, urea-melamine resins and melamine-formaldehyde resins. Also preferred are the C ₁ -C ₄ alkyl, in particular methyl ether of these formaldehyde resins and the mixtures with these formaldehyde resins. In particular, melamine-formaldehyde resins and / or their methyl ethers are preferred.

In the methods known from the copying paper ago the resins used as prepolymers. The prepolymer is still in the aqueous Phase soluble and migrates in the course of the polycondensation at the interface and surrounds the oil droplets. Methods of microencapsulation with formaldehyde resins are general known and for example in EP-A-562 344 and EP-A-974 394 described.

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.

Prefers become microcapsules whose capsule wall is a highly cross-linked methacrylic ester polymer. The degree of crosslinking is in this case with a crosslinker content ≥ 10 wt .-% achieved based on the total polymer.

In the preferred microcapsules, the wall-forming polymers of 30 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, especially 10 to 50% by weight, of a bifunctional 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 40% by weight, preferably 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 dissolved in water not soluble or sparingly soluble but have good to limited solubility in the lipophilic Have substance. Under low solubility is a solubility less than 60 g / l at 20 ° C to understand.

Under bi- or polyfunctional monomers are compounds, which have at least 2 non-conjugated ethylenic double bonds. Primarily Divinyl and Polyvinylmonomere come into consideration, the a cross-linking of the capsule wall during cause the polymerization.

Preferred bifunctional monomers are the diesters of diols with acrylic acid or methacrylic acid, also 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. Especially preferred are propanediol, butanediol, pentanediol and hexanediol diacrylate or the corresponding methacrylates.

preferred Polyvinyl monomers are trimethylolpropane triacrylate and methacrylate, Pentaerythritol triallyl ether and pentaerythritol tetraacrylate.

When Monomers III, other monomers are contemplated, are preferred Monomers IIIa such as styrene, α-methylstyrene, β-methylstyrene, Butadiene, isoprene, vinyl acetate, vinyl propionate and vinyl pyridine.

Especially preferred are the water-soluble Monomers IIIb, 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. Besides in particular N-methylolacrylamide, N-methylolmethacrylamide, dimethylaminoethylmethacrylate and diethylaminoethyl methacrylate.

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

The preferred microcapsules and their preparation are known from EP-A-457 154 known to the express is referenced. How to make the microcapsules in the way that from the monomers, a radical starter, 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. The proportion of oil phase in the oil-in-water emulsion is preferably at 20 to 60 wt .-%.

Then you solve the Polymerization of the monomers by heating, the resulting Polymers form the capsule wall, which encloses the lipophilic substance.

In usually leads the polymerization at 20 to 100 ° C, preferably at 40 to 80 ° C by. Naturally should the dispersion and polymerization temperature above the Melting temperature of the lipophilic substances are such that one optionally selects radical starter, their decomposition temperature above the melting point of the lipophilic Substance lies.

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

process engineering It is usually done in such a way that you have a mixture of water, Monomers, protective colloids, the lipophilic substances, radical initiators and, if appropriate, regulators are dispersed successively or simultaneously and with vigorous stirring heated to the decomposition temperature of the radical starter. The speed The polymerization can by choosing the temperature and the Amount of radical initiator to be controlled. Conveniently, start the reaction by raising the temperature to an initial temperature and controls the polymerization by further increase in temperature.

To Reaching the final temperature is set the polymerization expediently still about for one Time of up to 2 hours to lower residual monomer levels.

in the Connection to the actual polymerization reaction at a conversion of 90 up to 99 wt .-%, it is usually advantageous, the aqueous Microcapsule dispersions largely free of odorants, such as residual monomers and other organic volatile To shape components. This can be done in a conventional manner physically by distillative removal (in particular via steam distillation) or by stripping with an inert gas. Further it can be done chemically, as described in WO 9924525, advantageous by redox-initiated polymerization, as in DE-A-4 435 423, DE-A-4419518 and DE-A-4435422.

you can in this way microcapsules with a mean particle size in the range from 0.5 to 100 μm with the particle size in known way over the shear force, the stirring speed, the protective colloid and its concentration can be adjusted.

preferred Protective colloids are water-soluble Polymers, as these are the surface tension the water of 73 mN / m maximum to 45 to 70 mN / m lower and thus ensure the formation of closed capsule walls as well as microcapsules with preferred particle sizes between 1 and 30 μm, preferably 3 and 12 μm, form.

In usually the microcapsules become in the presence of at least one produced organic protective colloid, which is both anionic and can also be neutral. Also can anionic and nonionic protective colloids used together become. If desired, inorganic protective colloids are preferably used in mixture with organic protective colloids.

organic neutral protective colloids are cellulose derivatives such as hydroxyethyl cellulose, Carboxymethylcellulose and methylcellulose, polyvinylpyrrolidone, Copolymers of vinylpyrrolidone, gelatin, gum arabic, xanthan gum, Sodium alginate, casein, polyethylene glycols, preferably polyvinyl alcohol and partially hydrolyzed polyvinyl acetates.

to Improvement of stability of the emulsions can anionic protective colloids are added. Especially important the concomitant use of anionic protective colloids at a high content on microcapsules in the dispersion, as it is without an additional ionic stabilizer for the formation of agglomerated microcapsules can come. These agglomerates reduce the yield of usable Microcapsules, if they are agglomerates of small capsules of 1 up to 3 μm Diameter and increase them the fragility when the agglomerates are larger than about 10 μm are.

When anionic protective colloids are polymethacrylic acid, the Copolymers of sulfoethyl acrylate and methacrylate, sulfopropyl acrylate and methacrylate, of N- (sulfoethyl) -maleimide, 2-acrylamido-2-alkyl sulfonic acids, styrenesulfonic and vinylsulfonic acid.

preferred Anionic protective colloids are naphthalenesulfonic acid and naphthalenesulfonic acid-formaldehyde condensates and especially polyacrylic acids and phenolsulfonic acid-formaldehyde condensates.

The anionic protective colloids are usually used in amounts of 0.1 used to 10 wt .-%, based on the water phase of the emulsion.

Prefers are inorganic protective colloids, so-called Pickering systems, which allow stabilization by very fine solid particles and insoluble in water, but are dispersible or insoluble and not dispersible in water but wettable by the lipophilic Substance are.

Microencapsulations using such Pickering systems are for example in the US 3,615,972 and US 4,016,110 described.

One Pickering system can be made of the solid particles alone or additionally consist of excipients that control the dispersibility of the particles in water or the wettability of the particles by the lipophilic phase improve. These aids are e.g. nonionic, anionic, cationic or zwitterionic surfactants or polymeric protective colloids, as described above or below. In addition, buffer substances can be added, to set certain, respectively advantageous pH values of the water phase. This can be the water solubility reduce the fine particles and increase the stability of the emulsion. Usual buffer substances are phosphate buffer, acetate buffer and citrate buffer.

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

The Pickering systems can Both are added first in the water phase, as well as to the stirred emulsion of oil-in-water be added. Some fine, solid particles are produced by precipitation. Thus, the magnesium pyrophosphate is formed by combining the aqueous Solutions from Sodium pyrophosphate and magnesium sulfate produced.

In general, the pyrophosphate immediately prior to dispersion by combining an aq solution of an alkali metal pyrophosphate with at least the stoichiometrically required amount of a magnesium salt prepared, wherein the magnesium salt may be in solid form or aqueous solution. In a preferred embodiment, the magnesium pyrophosphate is prepared by combining aqueous solutions of sodium pyrophosphate (Na ₄ P ₂ O ₇ ) and magnesium sulfate (MgSO ₄ .7H ₂ O).

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

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

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

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

The Microcapsules can as a powder or preferably as a dispersion in the molding material forming mass be incorporated. In this case, preferably 1 to 40 wt .-%, in particular 5 to 25 wt .-%, microcapsules based on the total weight of molding from haufwerksporigem concrete (dry matter) incorporated.

concrete is a mineral building material that comprises hardening a mixture Cement, concrete aggregates, water and, where appropriate, concrete additives arises. The expert distinguishes according to the dry bulk density of Concrete between lightweight concrete, normal concrete and heavy concrete.

Concrete is also divided into "muddy" and "heapy" mixtures. Microstructured mixtures contain so much mineral mortar that all volumes between the aggregates are filled. Such concretes are also called normal concrete and are characterized by a dry density of 2.0-2.8 kg / dm ³ . Sponge mixtures contain significantly less mineral mortar, creating air pores in the stone structure. The density of the concrete is correspondingly lower. For the purposes of this application, the term "hard-core" concrete is to be understood as meaning an open-pore lightweight concrete with a dry bulk density <2 kg / dm ³ .

Used according to the invention Aggregates are surcharges, where finer proportions are avoided. Split is preferred with a grain size of 0.5-10 mm, especially 1-5 mm added.

Under Cement is understood to mean finely ground hydraulic binders, ie Mineral substances that harden stone-like when absorbed by water. cement consists predominantly from calcium silicates, aluminates and ferrites. The used for the molding according to the invention Cement is more commercially available Cement as CEM I-IV according to DIN EN 197-1. Of course it is also possible white cement for example, for the bright coloring of To use concrete. If necessary, conventional concrete additives can be added to improve processability. As concrete additives are superplasticizer on melamine resin or lignin sulphonate basis or polycarboxylate ethers called by way of example.

The mixture of the starting ingredients contains in each case based on the total solids content 10-49% by weight cement 50-89% by weight aggregates 0-5% by weight Concrete additives and 1-25% by weight Microcapsules with a polymer as a capsule wall and a capsule core, which consists predominantly of latent heat storage materials.

Preference is given to starting mixtures containing 20-30% by weight cement 65-75% by weight aggregates 0-3% by weight Concrete additives and 5-15% by weight Microcapsules.

The Solid starting ingredients are combined with water to form a mortar a water-cement ratio from 0.2 to 1.4, preferably 0.5 to 1.0 mixed. Usually become the starting ingredients and water at high speed to homogeneity mixed.

These Mixture is then filled into the appropriate molds. Usually Compaction takes place by strong shaking under pressure. Surprisingly does this not to destruction the pressure-sensitive microcapsules.

The inventive molding itself can have any shape, provided it makes sense for the sound insulation is. They are beneficial for the erection of load-bearing or non-load-bearing masonry and / or as on surfaces attached components. Examples are bricks, which are compounded with mortar be, ceiling elements, pillars, pedestals or sound-absorbing Cladding elements on traffic routes or in buildings.

The show moldings according to the invention good sound-absorbing properties combined with good heat-absorbing properties Properties. Despite the high microcapsule content, they seem to be responsible for sound absorption important open pores are not clogged. The moldings show a much faster heat exchange as conventional Moldings. Also, the capsules in the finished molded body are still undamaged, so that no pollution of the room air due to evaporation is to be observed.

Also for outdoor applications such as noise barriers for motorway or railway lines, the moldings are suitable as a whole less condensate accumulates and thus reduce pollution from algae and fungi. About that In addition, the moldings according to the invention prevent rapid application in outdoor applications Icing of the pores contained in the stone, which reduce the sound insulation would.

The following examples are intended to explain the invention in more detail: Preparation of the Microcapsules Water Phase: 572 g water 80 g a 50% strength by weight colloidal dispersion of SiO ₂ in water at pH 9.3 (average particle size 108.6 nm, Z average after light scattering)) 2.1 g a 2.5% by weight aqueous sodium nitrite solution 20 g a 1% strength by weight aqueous methylcellulose solution (viscosity 15000 mPas at 2% in water) Oil phase: 440 g C ₁₆ -C ₁₈ alkane mixture (26 ° C melting temperature) 77g methyl methacrylate 33 g butanediol 0.76 g ethylhexyl 1.35 g t-butyl perpivalate
Feed 1: 1.09 g of t-butyl hydroperoxide, 70% strength by weight in water
Feed 2: 0.34 g ascorbic acid, 0.024 g NaOH, 56 g H ₂ O.

At room temperature, the above water phase was initially charged and adjusted to pH 4 with 3 g of 10% nitric acid. After addition of the oil phase was dispersed with a high-speed dissolver at 4800 rpm. After 40 minutes of dispersion, a stable emulsion of particle size 1 to 9 microns in diameter was obtained. The emulsion was heated to 56 ° C. in 40 minutes while stirring with an anchor raker, in within a further 20 minutes at 58 ° C, within a further 60 minutes at 71 ° C and heated to 85 ° C within a further 60 minutes. The resulting microcapsule dispersion was cooled with stirring to 70 ° C and the feed 1 was added. Feed 2 was metered in with stirring at 70 ° C. for 80 minutes. It was then cooled. The resulting microcapsule dispersion had a solids content of 47.2 wt .-% and an average particle size 5.8 microns (volume average, measured by Fraunhofer diffraction).

The Dispersion was achieved in a laboratory spray dryer with two-fluid nozzle and cyclone separation with 130 ° C Inlet temperature of the heating gas and 70 ° C outlet temperature of the powder from the spray tower easily be dried. Microcapsule dispersion and powder showed at Heating in differential calorimetry at a heating rate of 1 K / minute a melting point between 24.5 and 27.5 ° C with a Conversion enthalpy of 110 J / g alkane mixture.

Production of a sound absorber stone

It were cement-bound sound absorber stones (39 × 9 × 19 cm, equivalent to 8 kg of stone) with microencapsulated latent heat storage materials in a usual Production plant for Made of lightweight concrete blocks. For this purpose, 1.5 t split 2/5, 0.7 t split 1/3, 0.5 t cement CEM I WS, 0.1 t setting agent, 0.1 t of microcapsules described above mixed with 0.35 t of water for 3 minutes. The mixture was subsequently transferred into a metal mold and by means of plunger and vibrating energy for about. Compacted for 15 seconds. After that opened the mold and the preformed sound absorber stones became 4 days cured at room temperature. One single sound absorber brick contains 400 g microcapsules. from Stone was cut a sample (stone 1).

To the Comparison sound absorber stones were made according to the above rule, but they did not contain microcapsules. From one of these stones a sample was cut (stone 2).

The directly after demolding resulting stones according to the invention felt cold (feeling). The stones not according to the invention have after shaking through the registered vibration energy a temperature of about 35 ° C.

Subsequently was the heat capacity of the sound absorber brick according to the invention measured. For this purpose, a calorimeter apparatus was built into which both the sample of the prepared stone of known weight and temperature, as well as a known amount of water with defined Temperature was introduced. The time to temperature stability was determined. The resulting mixture temperature is a direct one Effect of specific heat capacity and initial temperatures of water and sample.

Table 1: Determination of the heat capacity of the sound absorber stones Stone 1 (with 5 wt% microcapsules): volume 462 cm ³ , density 1.89 g / cm ³ Stone 2 (without microcapsules): volume 566 cm ³ , density 1.87 g / cm ³

The measurement gives a specific amount of heat for stone 1 of 67 J / cm ³ and 56 J / cm ³ for stone 2. Stone 1 also gave off its heat significantly faster. In the case of stone 1, a temperature stability was already reached after 0.25 hours, while the time until the temperature stability of stone 2 was 1.25 hours. The shaped bodies according to the invention thus have a greater heat input and a 5 times faster response time than the comparative shaped bodies.

Farther were electron micrographs of broken samples made of concrete block matrix. There were no broken capsules found.

Claims (9)

Sound-absorbing shaped body made of hspwerksporigem concrete, whose pores have an average diameter of 0.2-4 mm, characterized in that the concrete microcapsules with a polymer as a capsule wall and a capsule core, consisting mainly of latent heat storage materials containing. Sound-absorbing molded body according to claim 1, characterized characterized in that the latent heat storage materials lipophilic substances with a solid / liquid phase transition in the temperature range from -20 to 120 ° C are. Sound-absorbing shaped bodies according to Claim 1 or 2, characterized in that the latent heat storage materials aliphatic Hydrocarbon compounds are. Sound-absorbing shaped bodies according to one of claims 1 to 3, characterized in that the capsule wall is a highly cross-linked methacrylic ester is. Sound-absorbing shaped body according to one of claims 1 to 4, characterized in that the capsule wall is constructed from From 30 to 100% by weight one or more C ₁ -C ₂₄ -alkyl esters of acrylic and / or methacrylic acid (monomers I), 0 to 80% by weight a bi- or polyfunctional monomer (monomer II) which is insoluble or sparingly soluble in water, and 0 to 40% by weight other monomers (monomers III) in each case based on the total weight of the monomers. Sound-absorbing shaped bodies according to one of claims 1 to 5, characterized in that the microcapsules by heating an oil-in-water emulsion, in the the monomers, a radical initiator and the latent heat storage materials as disperse phase available are. Sound-absorbing shaped bodies according to one of claims 1 to 6, characterized in that the microcapsules by polymerization the monomers that react with the radical initiator and the latent heat storage materials as a disperse phase with an inorganic protective colloid of an oil-in-water emulsion available, available are. Sound-absorbing shaped bodies according to one of claims 1 to 7, characterized in that as an aggregate split with a Grain size of 0.5-10 mm used. Use of the sound-absorbing molded body according to claims 1 to 8 for the construction of load-bearing or non-structural masonry and / or as on surfaces attached components.