WO2008116763A1

WO2008116763A1 - Modified polyurethane foamed plastics containing microencapsulated latent heat storage material

Info

Publication number: WO2008116763A1
Application number: PCT/EP2008/053082
Authority: WO
Inventors: Hildegard Stein; Andreas Arlt; Michael Klemm
Original assignee: Basf Se
Priority date: 2007-03-26
Filing date: 2008-03-14
Publication date: 2008-10-02

Abstract

The present invention relates to modified polyurethane foamed plastics comprising an open-cell polyurethane foam matrix and 5 kg to 70 kg of microcapsules per m3 of foam. The microcapsules comprise a capsule core made of a latent heat storage material and a capsule wall which is made up of from 30% to 100% by weight, based on the total weight of the monomers, of at least two monomers which are different from one another (monomer I) from the group comprising C1-C24 alkyl esters of acrylic and/or methacrylic acid, acrylic acid, methacrylic acid, and maleic acid; 0% to 70% by weight, based on the total weight of the monomers, of one or more bifunctional or polyfunctional monomers (monomer II) which are not soluble or which are highly soluble in water; and 0% to 40% by weight, based on the total weight of the monomers, of one or more other monomers (monomer III) which are distributed in the cells of the foam matrix. The invention further relates to a method for the production of said polyurethane foamed plastics and to the use of said polyurethane foamed plastics as mattress toppers.

Description

Modified polyurethane foams containing microencapsulated latent heat storage material

description

The present invention relates to modified polyurethane foams containing microencapsulated latent heat storage material, a process for their preparation and their use as a mattress overlay.

Microcapsules with wall material based on a highly crosslinked methacrylic acid ester polymer are known from EP-A-1 029 018, DE-A-101 39 171, WO 2005/1 16559 and the older European application no. 06117092.4 known. They all relate to microencapsulated latent heat storage materials in a wide variety of construction applications. The earlier European Application No. 06126017.0 teaches highly crosslinked microcapsules based on methacrylic acid esters for textile and foam applications.

With latent heat storage material modified foams are known. Thus, WO 98/46669 describes thin-layer, open-celled polyurethane foams, for example for car skies, which are coated with a microcapsule / binder dispersion. With foam thicknesses of 2.5 to 4 mm, penetration depths of 50% are achieved. However, this is a coating that has a natural limit on large order quantities. So 84 g of microcapsules per m ^{2 are} applied, which has a rather low heat storage effect. According to this document, microcapsules with a gelatin wall are suitable. A very similar teaching is US 5,677,048, which teaches thin-layer, fabric-bonded, coated foams which are useful in shoe inner liners.

JP 2003-011256 and JP 2003-012853 also teach polyurethane foams, the surface of which is coated to a penetration depth of 2 mm with a microcapsule / binder dispersion. The addition of binder and thickener prevents a deeper penetration of the microcapsules in the foam. In order to ensure a fixation of the microcapsules, the surface is then coated with a polypropylene film.

The general problem of coatings is that too small amounts of latent heat storage material can be applied in order to achieve a good temperature-compensating effect. As a rule, the surface finish also suffers from such a coating.

From JP 10-300373 polyurethane foams are known which contain 20 to 80 wt .-%, based on the treated polyurethane foam, microencapsulated latent heat storage material. In addition to the addition of the microcapsules in the foam-forming process, other methods of preparation include coating or impregnation. nierung with a microcapsule dispersion described. The foams are suitable for use in mattresses, pillows and clothing.

JP 2001-302841 teaches a flexible polyurethane foam with an initial volume weight of 40 kg / m ³ which is impregnated with a binder mixture containing a microencapsulated latent heat storage material.

JP 2001-299538 describes a cushion consisting of a polyurethane core and a 4 mm thick outer layer, which is also a polyurethane foam whose density is 50 kg / m ³ . This outer layer contains 30% by weight of microencapsulated latent heat storage material.

DE 10 2004 031 529 describes polyurethane foams to which microencapsulated latent heat storage material with wall material based on methyl methacrylate was mixed before foaming. However, due to the manufacturing process, the latent heat storage material is uniformly distributed in the foam and, based on the volume, achieves a content of 7 g of microcapsules per liter of foam. Now, if such foams are used as mattresses, the experiments have shown that the user is observed only a small effect.

The object of the present invention was thus to provide a larger content of microcapsules in the foam. Furthermore, it was an object to present the foam in a form which has an advantageous distribution of the microencapsulated latent heat storage material and thus offers a high level of comfort. Finally, the foam should have good fastness to moisture, bodily fluids, laundry or cleaning.

Accordingly, a modified polyurethane foam comprising an open cell polyurethane foam matrix and 5-70 kg microcapsules per m ³ foam, wherein the microcapsules comprise a capsule core of latent heat storage material and a capsule wall constructed of

From 30 to 100% by weight, based on the total weight of the monomers, of at least one monomer (monomers I) from the group comprising C ₁ -C ₂₄ -alkyl esters of acrylic and / or methacrylic acid, acrylic acid, methacrylic acid and maleic acid,

0 to 70 wt .-% based on the total weight of the monomers, one or more bi- or polyfunctional monomers (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 wherein the microcapsules are substantially distributed in the cells of the foam matrix, a process for their preparation and their use as a mattress overlay found.

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

The average particle diameter of the microcapsules (Z means by means of light scattering) is 0.5 to 50 μm, preferably 0.5 to 30 μm. The weight ratio of capsule core to capsule wall is generally from 50:50 to 95: 5, preferably from 70:30 to 93: 7.

The capsule wall generally contains at least 30% by weight, preferably at least 40% by weight, in a particularly preferred form at least 50% by weight, in particular at least 60% by weight, very particularly preferably at least 70% by weight. and up to 100% by weight, preferably at most 90% by weight, in particular at most 85% by weight and very particularly preferably at most 80% by weight of at least one monomer from the group comprising C 1 -C ₂₄ -alkyl esters of acrylic and / or methacrylic acid, acrylic acid, methacrylic acid and / or maleic acid (monomers I), copolymerized, based on the total weight of the monomers.

Preferably, at least 2 different monomers I are used to prepare the capsule wall.

Furthermore, the capsule wall preferably contains at least 10 wt .-%, preferably at least 15 wt .-%, preferably at least 20 wt .-% and generally at most 70 wt .-%, preferably at most 60 wt .-% and in a particularly preferred form at most 50% by weight of one or more difunctional or polyfunctional monomers which are insoluble or sparingly soluble in water (monomers II), based on the total weight of the monomers.

In addition, the capsule wall may contain up to 40% by weight, preferably up to 30% by weight, in particular up to 20% by weight, of other monomers III in copolymerized form.

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 (monomers Ia). Furthermore, the unsaturated C3 and C4 carboxylic acids such as acrylic acid, methacrylic acid and maleic acid (monomers Ib) are suitable. Especially 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. Generally, the methacrylates and methacrylic acid are preferred.

According to a preferred embodiment, the microcapsule walls of 25 wt .-% to 75 wt .-% of maleic acid and / or acrylic acid, in particular methacrylic acid, constructed.

Suitable monomers II are bi- or polyfunctional monomers which are insoluble or sparingly soluble in water but which have better solubility in the lipophilic substance. Low solubility is to be understood as meaning a solubility of less than 60 g / l at 20 ^° C. By bi- or polyfunctional monomers is meant compounds having at least two non-conjugated ethylenic double bonds. In particular, divinyl and polyvinyl monomers come into consideration. They cause a crosslinking of the capsule wall during the polymerization. One or more divinyl monomers and one or more polyvinyl monomers can be polymerized in.

According to a preferred embodiment, monomer II used is a mixture of divinyl and polyvinyl monomers, the proportion of polyvinyl monomers being from 2 to 90% by weight, based on the sum of divinyl and polyvinyl monomers. The proportion of polyvinyl monomers is preferably from 5 to 80% by weight, preferably from 10 to 60% by weight, based on the sum of divinyl and polyvinyl monomers. For microcapsules having a mean particle size <2.5 microns, the Polyvi- nylanteil is preferably 20 to 80 wt .-%, in particular 30 to 60 wt .-% based on the sum of divinyl and polyvinyl monomers. For microcapsules having a mean particle size> 2.5 microns, the polyvinyl is preferably from 5 to 40 wt .-%, in particular 10 to 30 wt .-% based on the sum of divinyl and polyvinyl monomers.

Suitable divinyl monomers are divinylbenzene and divinylcyclohexane. Preferred divinyl monomers 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, methallyl methacrylamide, allyl acrylate and allyl methacrylate. Particular preference is given to propanediol, butanediol, pentanediol and hexanediol diacrylate and the corresponding methacrylates.

Preferred polyvinyl monomers are trivinylbenzene, trivinylcyclohexane and preferably the polyesters of polyols with acrylic acid and / or methacrylic acid, furthermore the polyalkylene and polyvinyl ethers of these polyols. Preference is given to trimethylolpropane triacrylate and methacrylate, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, pentaerythritol triacrylate and pentaerythritol tetraacrylate and their technical mixtures. Preference is given to the combinations of divinyl and polyvinyl monomers, such as butanediol diacrylate and pentaerythritol tetraacrylate, hexanediol diacrylate and pentaerythritol tetraacrylate, butanediol diacrylate and trimethylolpropane triacrylate, and hexanediol diglycol and trimethylolpropane triacrylate.

Suitable monomers III are other monomers which are different from the monomers I and II, such as vinyl acetate, vinyl propionate, vinylpyridine and styrene or α-methylstyrene. Particular preference is given to charge-bearing or ionizable group-carrying monomers IIIa which are different from the monomers I and II, such as itaconic acid, maleic anhydride, 2-hydroxyethyl acrylate and methacrylate, acrylamido-2-methylpropanesulfonic acid, N-vinylpyrrolidone, N-methylolacrylamide, N-methylolmethacrylamide, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate, furthermore methacrylonitrile, acrylonitrile and methacrylamide.

Preferably, the capsule wall is constructed from

From 30 to 90% by weight of one or more C 1 -C 24 -alkyl esters of acrylic and / or methacrylic acid, acrylic acid, methacrylic acid and / or maleic acid (monomers I),

From 10 to 70% by weight of a mixture of divinyl and polyvinyl monomers (monomers II), where the proportion of polyvinyl monomers is from 2 to 90% by weight, based on the monomers II, and

0 to 30% by weight of one or more other monomers (monomer III)

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

Particularly preferably, the capsule wall is constructed from

30 to 90 wt .-% of a mixture of monomers Ia and Ib, wherein the proportion of the

Monomers Ib <25% by weight, based on the total weight of all monomers I, II and III,

From 10 to 70% by weight of a mixture of divinyl and polyvinyl monomers (monomers II), the proportion of polyvinyl monomers being from 2 to 90% by weight based on the monomers II and

From 0 to 30% by weight of other monomers III,

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

According to a further particularly preferred embodiment, the capsule wall is constructed from 30 to 90 wt .-% of a mixture of monomers Ia and Ib, wherein the proportion of the

Monomer Ib> 25% by weight, based on the total weight of all monomers 1, 11 and III,

From 0 to 30% by weight of other monomers III,

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

The core material of the microcapsules is a latent heat storage material, also known as PCM (Phase Change 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, it is an organic lipophilic substance having a solid / liquid phase transition in the temperature range from -20 to 120 ⁰ C.

Examples include:

aliphatic hydrocarbon compounds, such as saturated or unsaturated C 10 -C 40 -hydrocarbons, which are branched or preferably linear, e.g. such as n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, n-eicosane, n-heneicosane, n -docosan, n-tricosane, n-tetracosane, n-pentacosane, n Hexacosan, n-heptacosane, n-octacosane and cyclic hydrocarbons, eg Cyclohexane, cyclooctane, cyclodecane; aromatic hydrocarbon compounds such as benzene, naphthalene, biphenyl, o- or m-terphenyl, mono- or polysubstituted Ci-C4o-alkyl-substituted aromatic hydrocarbons such as para -XyIoI, n-dodecylbenzene, n-tetradecylbenzene, n-hexadecylbenzene, ß-n-hexylnaphthalene or ß-n-decylnaphthalene; saturated or unsaturated Cβ-Cso 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 waxes wax, ethylene vinyl acetate wax or hard waxes according to Fischer-Tropsch

Method; 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 application of the latent heat storage is desired, the latent heat storage materials are selected. For example, used for latent heat storage in building materials in a moderate climate preferred latent heat storage materials whose solid / liquid phase transition in the temperature range of 0 to 60 ⁰ C. Thus, selects a rule for indoor applications individual substances or mixtures with transition temperatures 15-30 ⁰ C. mainly transformation temperatures from 0 to 40 ° C are advantageous for applications in the textile sector.

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 used according to the invention can be prepared by a so-called in situ polymerization. The principle of microcapsule formation is based on the preparation of a stable oil-in-water emulsion from the monomers, a free radical initiator, at least one protective colloid and the lipophilic substance to be encapsulated. The polymerization of the monomers is then initiated by heating and, if appropriate, controlled by further temperature increase, the standing polymers form the capsule wall, which encloses the lipophilic substance. This general principle is described, for example, in DE-A-10 139 171, to the contents of which reference is expressly made.

In general, the microcapsules are prepared in the presence of at least one organic 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.

Depending on the preparation process and the selected protective colloid, this may also be part of the microcapsules. Thus, up to 10% by weight, based on the total weight of the microcapsules, may be protective colloid. According to this embodiment, the microcapsules on the surface of the polymer have the 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 with preferred particle sizes in the range of 0.5 to 50 .mu.m, preferably 0 , 5 to 30 microns in particular 0.5 to 10 microns, form. Organic protective colloids are preferably organic neutral protective colloids.

According to another embodiment, organic neutral protective colloids are preferred. Particularly preferred are OH-bearing protective colloids such as polyvinyl alcohols and partially hydrolyzed polyvinyl acetates.

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. Preferred organic neutral protective colloids are polyvinyl alcohol and partially hydrolyzed polyvinyl acetates and methylhydroxypropyl cellulose.

According to a preferred embodiment, mixtures of organic protective colloids such as polyvinyl alcohols are used together with cellulose derivatives.

The use of polyvinyl alcohol and / or teilhydrolysiertem polyvinyl acetate leads to stable emulsions even at small mean droplet sizes such as 1, 5 - 2.5 microns. The diameter of the oil droplets corresponds almost to the diameter of the microcapsules present after the polymerization. In general, protective colloid, in particular polyvinyl alcohol or partially hydrolyzed polyvinyl acetate, is used in a total amount of at least 3% by weight, preferably from 6 to 8% by weight, based on the microcapsules (without protective colloid). It is possible to add further protective colloids mentioned above in addition to the preferred amount of polyvinyl alcohol or partially hydrolyzed polyvinyl acetate. The microcapsules are preferably prepared only with polyvinyl alcohol and / or partially hydrolyzed polyvinyl acetate and without the addition of further protective colloids.

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

Preference is given to polyvinyl alcohols or partially hydrolyzed polyvinyl acetates whose viscosity of a 4 wt .-% aqueous solution at 20 ⁰ C according to DIN 53015 has a value in the range of 3 to 56 mPa s, preferably a value of 14 to 45 mPa s, in particular of 22 to 41 mPa-s. Preference is given to polyvinyl alcohols having a degree of hydrolysis of> 65%, preferably> 70%, in particular> 75%.

Organic anionic protective colloids are sodium alginate, polymethacrylic acid and their copolymers, the copolymers of sulfoethyl acrylate and methacrylate, sulfopropyl acrylate and methacrylate, N- (sulfoethyl) -maleimide, 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.

As inorganic protective colloids so-called Pickering systems are mentioned, which allow stabilization by very fine solid particles and are insoluble in water, but dispersible or insoluble and not dispersible in water, but wettable by the lipophilic substance. The mode of action and its use is described in EP-A-1 029 018 and EP-A-1 321 182, to the contents of which reference is expressly made. A Pickering system can consist of the solid particles alone or in addition of auxiliaries which improve the dispersibility of the particles in water or the wettability of the particles by the lipophilic phase.

The inorganic solid particles may be metal salts, such as salts, oxides and hydroxides of calcium, magnesium, iron, zinc, nickel, titanium, aluminum, silicon, barium and manganese. These include magnesium hydroxide, magnesium carbonate, magnesium oxide, calcium oxalate, calcium carbonate, barium carbonate, barium sulfate, titanium dioxide, aluminum oxide, aluminum hydroxide and zinc sulfide. Silicates, bentonite, hydroxylapatite and hydrotalcites are also mentioned. Particularly preferred are highly disperse silicas, magnesium pyrophosphate and tricalcium phosphate.

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

The highly dispersed silicas can be dispersed as fine, solid particles in water. But it is also possible to use so-called colloidal dispersions of silica in water. 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 Pickering system, it is advantageous if the pH of the oil-in-water emulsion is adjusted to pH 2 to 7 with an acid.

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.

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

It is also possible to add surfactants, preferably nonionic surfactants, for costabilization. Suitable surfactants can be found in the "Handbook of Industrial Surfactants", the content of which is expressly referred to The surfactants can be used in an amount of from 0.01 to 10% by weight, based on the water phase of the emulsion. Radical initiators for the free-radical polymerization reaction which can be used are the customary peroxo and azo compounds, advantageously in amounts of from 0.2 to 5% by weight, based on the weight of the monomer (s).

Depending on the state of aggregation of the radical initiator and its solubility behavior, it can be fed as such, but preferably as a solution, emulsion or suspension, as a result of which, in particular, small amounts of radical initiator can be metered more precisely.

Preferred free-radical initiators are tert-butyl peroxoneodecanoate, tertiary

Amyl peroxypivalate, dilauroyl peroxide, tert-amyl peroxy-2-ethylhexanoate, 2,2'-azobis (2,4-dimethyl) valeronitrile, 2,2'-azobis (2-methylbutyronitrile), dibenzoyl peroxide, tert-butylper-2-yl ethylhexanoate, di-tert-butyl peroxide, tert-butyl hydroperoxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane and cumene hydroperoxide.

Particularly preferred radical initiators are di (3,5,5-trimethylhexanoyl) peroxide, 4,4'-azobisisobutyronitrile, tert-butyl perpivalate and dimethyl 2,2-azobisisobutyrate. These have a half-life of 10 hours in a temperature range of 30 to 100 ⁰ C.

Furthermore, it is possible to add to the polymerization known to those skilled controller in conventional amounts, such as tert-dodecyl mercaptan or Ethylhexylthioglycolat.

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

In general, the polymerization is conducted at temperatures in the range of 20 to 120 ⁰ C and preferably from 40 to 95 ° C. Depending on the desired lipophilic substance, the oil-in-water emulsion should be formed at a temperature at which the core material is liquid / oily. Accordingly, a radical initiator is chosen whose decomposition temperature is above this temperature, and carries out the polymerization 2 to 50 K above this temperature, so that optionally selects radical initiator whose decomposition temperature is above the melting point of the lipophilic substance.

A common process variant for lipophilic substances with a melting point up to about 60 ⁰ C is a reaction temperature starting at 60 ° C, which is increased in the course of the reaction to 85 ° C. Advantageous free radical initiators have a 10-hour shelf life in the range of 45 to 65 ° C, such as tert-butyl perpivalate. According to a further process variant for lipophilic substances having a melting point above 60 ⁰ C, a temperature program is selected which starts at correspondingly higher reaction temperatures. For initial temperatures of around 85 ° C is chosen free-radical initiator with a 10-hour half-life in the range of 70 to 90 ⁰ C, preferably tert-butyl per-2-ethylhexanoate.

Conveniently, the polymerization is carried out at atmospheric pressure, but you can work even at reduced or slightly elevated pressure z. B. at a polymerization temperature above 100 ⁰ C, that is approximately in the range of 0.5 to 5 bar.

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

An advantageous process variant using polyvinyl alcohol and / or partially hydrolyzed polyvinyl acetate allows an advantageous procedure according to which is dispersed and polymerized directly at elevated temperature.

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.

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

It is possible to treat the microcapsules with polyelectrolyte, which may even improve the tightness of the capsules. Processes for their preparation and suitable polyelectrolytes are described in earlier international application PCT / EP2007 / 056786, to which reference is expressly made.

The microcapsules used according to the invention can preferably be used directly as an aqueous dispersion for the treatment of the foam. However, it is also possible to spray-dry the microcapsule dispersion to obtain a powder. The spray-drying and optionally used spray aids are described in WO 2006/053714, to which reference is expressly made.

To prepare the modified polyurethane foams according to the invention, an open-celled polyurethane foam is treated with a microcapsule dispersion. The open-cell polyurethane foam used in this case is obtained by reacting diisocyanates or polyisocyanates (a) with polyols (b).

In addition to the components diisocyanates or polyisocyanates (a), polyols (b), the following further optional components can also be used to prepare the foams used according to the invention:

(c) catalysts (d) blowing agent,

(e) additives, such as. As flame retardants, dyes, pigments, stabilizers, fillers and the like.

The polyurethane foams used according to the invention are synthesized from diisocyanates or polyisocyanates (a) customary in the polyurethane range. Aliphatic, cycloaliphatic, arylaliphatic and aromatic polyfunctional di- or polyisocyanates are generally suitable. Preference is given to the industrially readily available, optionally urethane-containing, aromatic di- and polyisocyanates, such as 2,4- and 2,6-toluene diisocyanate, and any desired mixtures of these isomers, 2,2'- and 2,4'- and 4,4 '. Diphenylmethane diisocyanate and any mixtures of these isomers, mixtures of 2,2'-2,4'-, 4,4'-diphenylmethane diisocyanates and polyphenyl polymethylene polyisocyanates (crude MDI) and mixtures of toluene diisocyanates and Roh MDI.

Polyisocyanates (a) can also be used in the form of polyisocyanate prepolymers. These prepolymers are known to the person skilled in the art. The preparation is carried out in a manner known per se, by reacting the above-described di- or polyisocyanates (a), for example at temperatures of about 80 ^° C., with the polyols (b) described below to give the prepolymer. The polyol-di- or polyisocyanate ratio is generally chosen so that the NCO content of the prepolymer 8 to 25 wt .-%, preferably 10 to 24 wt .-%, particularly preferably 13 to 23 wt .-% is ,

As polyols (b), polyether alcohols or polyester alcohols are generally used. However, other hydroxyl-containing polymers, for example polyesteramides and polyacetals, are also suitable. Suitable polyester alcohols are usually prepared by condensation of polyfunctional alcohols, preferably diols, having 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms, for example hexanediol, with polyfunctional carboxylic acids having 2 to 12 carbon atoms, for example adipic acid and / or phthalic acid. The polyether alcohols used usually have a functionality in the range from 2 to 6, in particular 4 to 3.

As polyols (b), polyether alcohols are preferably used. Suitable polyether alcohols are described below under component (b-1).

In general, the polyether polyols used have an OH number of from 15 to 200, preferably from 20 to 120, particularly preferably from 22 to 90, and a nominal functionality of from 2 to 4, preferably from 2.2 to 2.9.

Optionally, component (b) may also comprise further compounds with isocyanate-reactive hydrogen atoms, these compounds preferably having two or more reactive groups selected from OH groups, SH groups, NH groups, Nhb groups and CH-acidic groups, such as ß-diketo groups, carry in the molecule. Depending on the presence of these compounds in component (b), in the context of this invention the term polyurethanes generally comprises polyisocyanate polyaddition products, for example also polyureas.

In a preferred embodiment, the polyols (b) include components (b-1) polyether polyols having an OH number of from 15 to 200 and (b-2) polymer polyols.

The polyether polyols (b-1) used are generally prepared by known processes, for example by anionic polymerization with alkali metal hydroxides, such as sodium or potassium hydroxide or alkali metal alkoxides, such as sodium methylate, sodium or potassium ethylate or potassium isopropoxide as catalysts and with addition of at least one starter molecule, containing 2 to 4 reactive hydrogen atoms bound, or by cationic polymerization with Lewis acids, such as antimony pentachloride, borofluoro etherate and others or bleaching earth as catalysts of one or more alkylene oxides, selected from propylene oxide (PO) and ethylene oxide (EO) prepared.

As polyether polyols (b-1), so-called low-unsaturated polyether polyols can be further used. In the context of this invention, low-unsaturated polyols are understood as meaning, in particular, polyether alcohols having an unsaturated compound content of less than 0.02 meq / g, preferably less than 0.01 meq / g. Such polyether alcohols are prepared by addition of ethylene oxide and / or propylene oxide and mixtures thereof, prepared at least difunctional alcohols in the presence of so-called double metal cyanide catalysts.

The alkylene oxides can be used individually, alternately one after another or as mixtures. The use of an EO / PO mixture leads to a polyether polyol with random PO / EO unit distribution. It is possible first to use a PO7EO mixture and then, before termination of the polymerization, to use only PO or EO, then a polyether polyol with PO or EO endcap is obtained.

Suitable starter molecules are customary starter molecules in polyurethane chemistry, as mentioned in DE 10 2004 031 529, to which reference is expressly made.

The polyether polyols are present individually or in the form of a mixture of two or more of the aforementioned polyether polyols.

As component (b-2) so-called polymer polyols, which are also often referred to as graft polyols used. These polymer polyols are usually prepared by free-radical polymerization of suitable olefinic monomers, for example styrene, acrylonitrile, acrylates and / or acrylamide, in a polyetherol which serves as a graft base. The side chains are generally formed by transferring the radicals from growing polymer chains to polyether polyols. In addition to the graft copolymer, the polymer polyol predominantly contains the homopolymers of the olefins dispersed in unchanged polyetherol.

In a preferred embodiment, acrylonitrile, styrene, in particular styrene and acrylonitrile in the ratio between 1: 1 to 3: 1, and optionally in the presence of other monomers, a macromer, a moderator and using a radical initiator, usually azo or as monomers Peroxide compounds, in a Polyether- rol or polyesterol produced as a continuous phase.

As carrier polyetherols are usually compounds having a hydroxyl group functionality of 1, 8 to 8, preferably 2 to 3, a hydroxyl value of 20 to 100 mg KOH / g, preferably 25 to 70 mg KOH / g, prepared by anionic, cationic see or neutral polymerization (DMC) of alkylene oxides, preferably ethylene and / or propylene oxide into consideration.

Macromers, also referred to as stabilizers, are linear or branched polyols having number average molecular weights of up to 2000 g / mol and containing at least one terminal, reactive olefinic unsaturated group. The ethylenically unsaturated group can be synthesized by reaction with anhydrides (maleic anhydride, fumaric acid), acrylate and methacrylate derivatives and isocyanate derivatives, such as 3-iso-unsaturated propenyl-1, 1-dimethylbenzyl isocyanates, isocyanato-ethyl methacrylates, are added to an existing polyol.

During radical polymerization, the macromers are incorporated into the copolymer chain. This forms block copolymers with a polyether and a poly-acrylonitrile-styrene block which act as phase mediators in the interface of continuous phase and dispersed phase and suppress the agglomeration of the polymer polyol particles. The proportion of macromers is usually 1 to 15 wt .-%, based on the total weight of the monomers used for the preparation of the polymer polyol.

For the preparation of polymer polyols, modifiers, also referred to as chain transfer agents, are usually used, as mentioned in DE 10 2004 031 529, to which reference is expressly made.

To initiate the free-radical polymerization, customary initiators are used in conventional amounts, as mentioned in DE 10 2004 031 529, to which reference is expressly made.

The free radical polymerization for the preparation of polymer polyols is usually carried out at temperatures of 70 to 150 ⁰ C and a pressure up to 20 bar due to the reaction rate of the monomers and the half life of the initiators. Preferred reaction conditions for the preparation of polymer polyols are temperatures of 80 to 140 ⁰ C at a pressure of atmospheric pressure to 15 bar.

Polymer polyols are made in continuous processes using continuous feed and off-stream stirred tanks, stirred tank cascades, tubular reactors and loop reactors with continuous feed and drain, or in batch processes by means of a batch reactor or a semi-batch reactor.

The polymer polyols (b-2) are preferably used in admixture with polyether polyols (b-1). In a preferred embodiment, the polymer polyol (b-2) is in an amount of 5 to 20 wt .-%, preferably from 6 to 18 wt .-%, particularly preferably from 8 to 15 wt .-%, based on the total weight of Component (b), before

In a preferred embodiment, the polyol component (b) further contains crosslinking agent as component (b-3). Suitable crosslinking agents are, for example, polyols, preferably polyether polyols, having a nominal functionality of more than 2, preferably from 3 to 4, and having an OH number of more than 200 to 2000, preferably 500 to 1200. Usually, crosslinking agents (b-3) are in an amount of from 0.1 to 5% by weight, preferably from 0.5 to 4% by weight, more preferably from 1 to 3% by weight, based on the total weight of Component (b), before.

As catalysts (c) for the preparation of the polyurethane foams suitable according to the invention it is possible to use the customary and known polyurethane-forming catalysts, for example organic tin compounds, such as tin diacetate, tin dioctoate, dialkyltin dilaurate, and / or strongly basic amines, such as triethylamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, 2-dimethylimidazole, dimethylcyclohexylamine, dimethylbenzylamine or, preferably, triethylenediamine. The catalysts are preferably used in an amount of 0.01 to 5 wt .-%, preferably 0.05 to 2 wt .-%, based on the weight of the isocyanates.

As propellant (d) for the production of the polyurethane foams suitable according to the invention it is preferred to use water which reacts with the isocyanate groups with liberation of carbon dioxide. Together with or in place of water, it is also possible to use physically active blowing agents, for example liquid CO 2, hydrocarbons, such as n-, iso- or cyclopentane, or halogenated hydrocarbons, such as dichloromethane, tetrafluoroethane, pentafluoropropane, heptafluoropropane, pentafluorobutane, hexafluorobutane, dichloromonofluoroethane, Ketones such as Acetone or acetals, e.g. Methylal be used. The amount of the physical blowing agent is preferably in the range from 1 to 15 wt .-%, in particular 1 to 10 wt .-%, the amount of water preferably in the range between 0.5 to 10 wt .-%, in particular 1 to 5 Wt .-%, based on the weight of the compounds having at least two active hydrogen atoms.

As auxiliaries and / or additives (e), it is possible to use, for example, surface-active substances, foam stabilizers, cell regulators, external and internal release agents, fillers, pigments, hydrolysis protection agents and fungistatic and bacteriostatic substances.

The preparation of the polyurethane foams suitable for the modification is preferably carried out by the one-shot process, for example by means of high-pressure or low-pressure technology. The foams can be made in open or closed metallic molds or by continuously applying the reaction mixture to belt lines to produce foam blocks.

It is particularly advantageous to use the so-called two-component method in which, as stated above, a polyol and an isocyanate component are produced and foamed together. The components are preferably at a temperature in the range of 15 to 90 ⁰ C, preferably 20 to 60 ⁰ C. and particularly preferably 20 to 35 ⁰ C mixed and brought into the mold, or on the belt line. The temperature in the mold is usually in the range of 20 and 1 10 ⁰ C, preferably 30 to 60 ⁰ C and particularly preferably 35 to 55 ⁰ C.

The foams used according to the invention - ie before their modification - may have a density of 5-100 kg / m ³ . Preferably low-density foams are selected, for example, from 5 to 25 kg / m ³ , particularly preferably from 10 to 20 kg / m ³ and in particular from 14 to 20 kg / m ³ . The production of foams of low density is known to the person skilled in the art, for example by direct delivery of the physical blowing agents (physical blowing agents) described as (d) to the mixing head of the polyurethane processing machine or by prior mixing of the blowing agents (d) with the polyols (b). , Another possibility for the production of foams with densities below 20 kg / m ³ consists in a special foaming process using reduced pressure. In this process, which is known to those skilled in the art under the name of VPF (Variable Pressure Foaming) process, the continuous foam production is carried out using a vacuum in an encapsulated polyurethane processing machine. Alternatively, in the batchwise preparation, the still-liquid polyurethane mixture can be discharged into a box before foaming and this box can be pushed into a pressure chamber. The foaming is then also carried out using a vacuum, whereby lower volume weights are obtained.

According to the invention open-cell foams are used. Open-celled foams are those which have an air permeability determined in accordance with DIN EN ISO 7231 (method for determining the air permeability at constant pressure) of> 2 dm ³ / s, preferably> 2.5 dm ³ / s.

The production of open-cell foams is known to the person skilled in the art. Thus, open-cell foams can be produced both chemically and physically. They are obtained, for example, by adding cell-opening compounds, for example polyols having a high content of ethylene oxide, to the reaction mixture. Further, they are obtained by adding a foam stabilizer having a low surface activity, for example, a silicone base. Another way to obtain open-celled foams is by varying the catalysis, for example, by reducing the proportion of metal-based catalyst (c). For example, in processes with tin dioctoate as catalyst, an increase in the proportion of polymer polyol (b-2) by the SAN particles (styrene-acrylonitrile copolymers) contained therein likewise leads to open-celled foams.

Furthermore, foams can be subsequently modified into open-cell foams by a physical process. In the person skilled in the term Reticulate known methods, the cells of the foam are burst in an explosion chamber with a blast gas mixture.

Foams suitable for the modification according to the invention usually have cell sizes in the range from 50 to 2000 .mu.m, preferably from 200 to 1200 .mu.m and particularly preferably from 400 to 800 .mu.m. The cell size and the distribution of the cell size can, as known in the art, be influenced by mechanical adjustment or chemical variation, for example by changing the mixing chamber pressure, the stirring speed, the choice of stirrer type and air supply to the mixing chamber and by gassing the polyols or isocyanates with intergass such as nitrogen. Likewise, the cell size and the regularity of the cell structure can also be influenced by the choice of the silicone-based foam stabilizer and the metal catalyst.

Preferably, a flexible polyurethane foam is selected for the modification with microcapsules. Flexible polyurethane foams have a tensile strength of> 50 kPa up. Polyurethane flexible foams are preferably selected which have a tensile strength in the range from 100 to 250 kPa and particularly preferably 150 kPa 250 kPa.

The foams can be made up after their production, ie before the modification, by means of horizontal or vertical cutting systems and cut into rolls. The foams are preferably cut in thicknesses of 1 to 100 mm, preferably 3 to 50 mm, particularly preferably 3 to 30 mm. In these thicknesses, for example, they are ideal as a mattress pad.

To prepare the modified polyurethane foams according to the invention, an open-cell foam is treated with a microcapsule dispersion. Preferably, the foam is impregnated with the microcapsule dispersion. This can be done, for example, by passing the foam through a bath containing a microcapsule dispersion, then pressing it off and then drying it. For this purpose, a dispersion of microcapsule powder in water and / or water-miscible solvent can be used or the aqueous microcapsule dispersion obtained directly from the microencapsulation process. Preferably, the ready-made foams are impregnated with the microcapsule dispersion.

Water and / or water-miscible solvents and their mixtures for impregnation or impregnation are suitable as dispersants for the microcapsules. Water-miscible solvents are to be understood as being miscible with water up to a quantity of 20% by weight, based on the mixture of water and solvent at 25 ° C. and 1 bar. Suitable water-miscible solvents are, for example, alcohols, such as methanol, ethanol, 1-propanol, 2-propanol, butanol, Glycerol, cyclohexanol, polypropylene glycols, polyethylene glycols, higher molecular weight polyols such as the above-mentioned inventive polyols (b), ketones such as acetone, and methyl ethyl ketone, ethers such as tetrahydrofuran and dioxane, and esters such. For example, methyl and ethyl acetate.

Alcohols and / or water and particularly preferably water are preferably used.

According to one variant, binders may also be added to the aqueous microcapsule dispersion. Suitable binders are, for example, film-forming polymers having a glass transition temperature in the range of -45 to 45 ° C, preferably -30 to 12 ° C. Suitable examples are acrylates, PU dispersions and resins, which optionally still have reactive groups for subsequent curing. Such binders can be found, for example, in WO 98/46669, to which reference is expressly made.

The solids content of the microcapsule dispersion is 10 to 80 wt .-%, preferably 20 to 60 wt .-% and particularly preferably 30 to 50 wt .-%.

The formulation for impregnating the foam may additionally contain up to 50% by weight, preferably up to 30% by weight, of binder (solid) based on the total formulation. Furthermore, surfactants or dispersants and defoamers can be added to the formulation.

The impregnation of the foam with the microcapsule dispersion may be carried out batchwise or continuously, but preferably continuously, wherein the foam to be impregnated as roll goods having a width of 50 to 3000 mm and a thickness of 1 to 100 mm, preferably 3 to 50, particularly preferably 3 - 30 mm through a variable volume trough, typically 300 - 600 l. This tub has an automatic level control. The foam is guided under slight bias via guide rollers through the microcapsule dispersion. The residence time of the foam in the microcapsule dispersion is a few seconds and is controlled by the speed of the roller drive. When the impregnated foam emerges from the impregnating trough, it then passes through a pair of rollers (padder), through which excess microcapsule dispersion can be pressed out. The percentage uptake of microencapsulated latent heat storage material in the foam will be controlled by simply varying the gap size of this pair of rollers. The gap is dependent on the foam thickness.

Subsequently, the impregnated roll goods is passed through a drying unit, wherein usually belt dryers are used, in which hot air over the Foam is passed. The drying temperature can be varied depending on the residence time between 50 ⁰ C and 160 ⁰ C.

According to this process, the modified polyurethane foams according to the invention comprising 5 to 70 kg microcapsules in a m ³ foam. Preference is given to modified polyurethane foams comprising 20 to 65 kg, in particular 30 to 60 kg of microcapsules per m ^{3 of} foam. Such concentrations show as mattress pad particularly good temperature-regulating properties without negatively influencing the elasticity. In addition, the pads can be washed or cleaned without losing their temperature-regulating properties.

Example A: Synthesis of the microcapsule dispersion:

water phase

380 g of water 190 g of a 5% strength by weight aqueous solution of methylhydroxypropylcellulose

(Culminal MHPC 100 ^®)

47.5 g of a 10% strength by weight aqueous polyvinyl alcohol solution (Mowiol 15-79) 2.1 g of a 2.5% strength by weight aqueous sodium nitrite solution

Oil phase 431 g techn. Octadecane, (91% purity)

9 g Sasolwax 6805 (higher melting paraffin)

19.6 g of methyl methacrylate 19.6 g of 1,4-butanediol diacrylate 9.8 g of methacrylic acid 0.7 g of a 75% strength by weight solution of tert-butyl perpivalate in aliphatic hydrocarbons

Addition 1 5.38 g of a 10% strength by weight aqueous solution of tert-butyl hydroperoxide

Feed 1 28.3 g of a 1, 1 wt .-% aqueous solution of ascorbic acid

a) At 40 ⁰ C, the above water phase was presented and after addition of the oil phase was dispersed with a high-speed Dissolverrührer at 6000 rpm. After 40 minutes of dispersion, a stable emulsion of average particle size D [4.3] = 3.6 μm in diameter was obtained. b) The emulsion was heated with stirring with an anchor crusher over a period of 60 minutes at 70 ⁰ C, heated to a temperature of 85 ⁰ C within another 60 minutes and held at this temperature for one hour. Add 1 was added and the resulting microcapsule dispersion was cooled within 30 minutes with stirring to 20 ⁰ C, while feed 1 was metered.

The resulting microcapsule dispersion had a solids content of 44% and an average particle size D [4.3] = 3.5 μm (measured by Fraunhoferbeugung), D (0, 9) = 5.67 microns, the half-width of the distribution was 2.8 μm, the chip 1, 33, the evaporation rate was 3.8%.

Examples 1-4: Adjustment of the absorbed amount of microencapsulated latent heat storage by varying the gap size in the padder machine

From roll material of an open-cell conventional polyurethane flexible slab having a net density of about 15 kg / m ³ , mats having the dimensions 40 × 30 × 2 (L × W × H) cm were cut out and placed in a glass vessel in 3000 ml of a microcapsule dispersion according to Example A with a solids content of about 44% and a viscosity of 300 mPa-s soaked. After soaking, the excess liquid was removed by calendering the foam sheets by a hand-held padder machine. The amount of microencapsulated latent heat storage material received, like Examples 1 to 4, is above all dependent on the gap dimension of the calender rolls in the padder machine and can thus be adjusted in a targeted manner. Subsequently, the foam mats were pre-dried at 150 ⁰ C for 5 minutes and then dried at room temperature to constant weight. Examples 3 and 4 show the good reproducibility of the impregnation process.

MK: microencapsulated latent heat storage material

1) based on untreated foam,

2) based on inventive foam substrate

As the comparison of Examples 1-3 shows, the uptake of the amount of microcapsule can be increased by increasing the gap dimension in the padder machine.

Example 5 Determination of the Heat Storage Capacity (Capacity) of the Microcapsules Impregnated Foams by Differential Scanning Calorimetry

The impregnated with microencapsulated latent heat storage material foams of Examples 1-3 was performed with a DSC 7 instrument the heat absorption or -abgäbe during heating to 60 ⁰ C and subsequent cooling to 0 ⁰ C at a heating or -Kühlrate of 10 K / min determined (sample weight 10 mg).

The following table shows the amounts of heat released or absorbed:

Example 6 Determination of Volatile and Condensable Components by Thermodesorption

With a sample of the impregnated foam from Example 2, the gaseous and condensable emissions were determined by means of automatic thermal desorption in accordance with the Daimler-Chrysler Test Instructions PB VWL 709 Issue 1 1.01.2001 or VDA 278 Recommendation. In particular, the emission of formaldehyde was analyzed.

Determination of volatile emissions (VOC):

From the sample of Example 2 3 per strip of approximately 5 mg were excised with a scalpel from the surface, gene eingewo- in a thermal desorption been dried by heating for 30 min at 90 ⁰ C heated. The thereby emitted volatiles were collected in an absorber with Tenax cartridge TA®, a porous resin based on poly (2,6-diphenylphenylen) oxide, at -30 ⁰ C and subsequently to 280 ° C for. The released compounds were identified by GC / MS coupling and identified with toluene as the external standard.

Determination of condensable emissions (FOG):

The desorption tubes containing the sample were heated at 120 ^° C. for 60 minutes after determining the volatile emissions and analyzed as above by GC / MS coupling.

Result:

Neither in the determination of volatile emissions nor in the condensable

Emissions could be detected formaldehyde.

Claims

claims

A modified polyurethane foam comprising an open-cell polyurethane foam matrix and 5-70 kg microcapsules per m ³ foam, the microcapsules comprising a capsule core of latent heat storage material and a capsule wall constructed of

From 30 to 100% by weight, based on the total weight of the monomers, of at least two different monomers (monomers I) from the group comprising C 1 -C 24 -alkyl esters of acrylic and / or methacrylic acid, acrylic acid, methacrylic acid and maleic acid,

0 to 70 wt .-% based on the total weight of the monomers, one or more bifunctional or polyfunctional monomers (monomers II), which is insoluble or sparingly soluble in water, and

0 to 40% by weight, based on the total weight of the monomers, of one or more other monomers (monomers III)

and distributed in the cells of the foam matrix.

2. Modified polyurethane foam according to claim 1, wherein the capsule wall of the microcapsules is constructed from

30 to 90 wt .-% of one or more Ci-C24-alkyl esters of acrylic and / or

Methacrylic acid, acrylic acid, methacrylic acid and / or maleic acid (monomers I),

0 to 30% by weight of one or more other monomers (monomer III)

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

3. A modified polyurethane foam according to claim 1 or 2, wherein the open-celled polyurethane foam has been cut to a thickness of 1 to 100 mm before being modified.

A modified polyurethane foam according to any one of claims 1 to 3, wherein the foam is obtainable by treating an open-celled polyurethane foam with a microcapsule dispersion.

5. A modified polyurethane foam according to any one of claims 1 to 4, obtainable by impregnating an open-celled polyurethane foam with a dispersion containing the microcapsules.

A modified polyurethane foam according to any one of claims 1 to 5, wherein the open-celled polyurethane foam has a density in the range of 5 to 25 kg / m ³ prior to modification.

A modified polyurethane foam according to any one of claims 1 to 6, wherein the open-celled polyurethane foam has a density in the range of 10 to 20 kg / m ³ prior to the modification.

8. A modified polyurethane foam according to any one of claims 1 to 7, containing 20-65 kg of microcapsules per m ^{3 of} foam.

9. A process for producing a modified polyurethane foam comprising an open-celled polyurethane foam matrix and 5-70 kg microcapsules per m ³ foam, the microcapsules comprising a capsule core of latent heat storage material and a capsule wall constructed of

0 to 70 wt .-% based on the total weight of the monomers, one or more bi- or polyfunctional monomers (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 distributed in the cells of the foam matrix by treating an open-celled polyurethane foam with a dispersion containing microcapsules.

10. Use of modified polyurethane foams according to claim 1 as a mattress pad.