EP2203397A1

EP2203397A1 - Hydraulically setting construction material mixtures containing microencapsulated lipophilic substances

Info

Publication number: EP2203397A1
Application number: EP08804629A
Authority: EP
Inventors: Bogdan Moraru; Marc Rudolf Jung; Stefan Becker; Timo Mangel; Joachim Pakusch; Robert Rupaner
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2007-09-25
Filing date: 2008-09-24
Publication date: 2010-07-07
Also published as: WO2009040359A1

Abstract

The invention relates to a novel use of microcapsules comprising a polymer capsule wall and a lipophilic substance as a capsule core, said lipophilic substance having a melting point of ≤120°C and a boiling point of ≥100 °C, as additives providing stability in freeze-thaw conditions in hydraulically setting construction material mixtures.

Description

Hydraulically setting building material mixtures containing microencapsulated lipophilic substances

description

The present invention relates to a novel use of microcapsules comprising a capsule wall of polymer and a lipophilic substance as a capsule core, which has its melting point <120 ⁰ C and their boiling point> 100 ⁰ C, as freeze-thaw stability additives in hydraulically setting building material mixtures.

For many years, one knows the aging problems of concrete. For example, an important research goal is to increase the resistance of concrete to frost and freeze-thaw cycles. The water trapped in the concrete is known to expand during freezing and leads to microcracking and thus frost damage.

For some time now, attempts have been made to tackle the problem by producing concrete containing air pores. This artificial introduction of air pores should provide for relaxation rooms for expanded ice and ice water. It has been found that for improved concrete durability, the distance of each point in the cement paste from the next artificial airpore should not exceed 0.008 inch (200 μm) (ASTM Standard 666C). This is done by mechanically stirring air bubbles into the concrete mass with the help of surface-active substances. However, the results can only be reproduced very poorly, since the entry of the air quantity and the size of the air pores are difficult to control and, moreover, are dependent on the temperature. Too little air intake results in insufficient freeze-thaw stability, while too high air intake decreases the strength of the concrete.

DE 10 2005 046 681 attempts to counteract this problem by achieving a defined introduction of air by the addition of hollow microspheres. These hollow microspheres are water-filled hollow particles with a polystyrene shell. They are obtained by allowing core / shell polymers to swell with a polymethacrylic acid core and a polystyrene shell in aqueous base. It is essential that the trapped in the hollow particles water diffuses out of the capsules, so that in principle cavities are enclosed in the concrete. It is thus a defined entry of pores.

A similar solution to the problem is described in US 2005/0274285, US 2005/0274294, US 2005/0284340 and WO 2005/123618, in which it adds capsules of vinylidene chloride and / or acrylonitrile as wall material and isopentane or isobutane as core material to the concrete. The capsules can be used expanded or unexpanded. Since the capsules are expandable, it must be the nuclear material is a volatile substance. Highly volatile core materials in the unexpanded state cause storage problems, as volatile core materials escape easily and are generally also flammable. The expanded capsule variant in turn has the disadvantage that they occupy a significantly larger volume due to their particle size up to 100 microns.

The use of microcapsules with a wall material based on polymethyl methacrylate and waxes as core material in mineral moldings is known from EP 1029018 and DE-A-10 2004 005912. The waxes used hereafter serve as latent heat storage material, since they absorb heat from the environment by the melting process and release it only on solidification. If the microcapsules are used in amounts above 10% by weight, based on the mineral binder, they bring about a perceptible regulation of the room temperature. They are used in particular in non-structural applications such as gypsum plaster, since the high microcapsule content has an influence on the mechanical properties.

The present invention was based on new freeze-thaw stability additives for hydraulically setting building material mixture as an object. Another object was to provide a light incorporation of freeze-thaw stabilizers into concrete that was virtually independent of external conditions, while the mechanical properties of the concrete should not be adversely affected.

Accordingly, the use of microcapsules comprising a capsule wall of polymer and a lipophilic substance as a capsule core, which has its melting point <120 ⁰ C and their boiling point> 100 ⁰ C, found as frost-thaw stability additives in hydraulically setting building material mixtures. The capsule core is thus solid or liquid depending on the temperature. Unlike in all approaches of the prior art, the present invention is not based on the principle of the defined gas input, but rather it was found that lipophilic

Substances with a melting point <120 ⁰ C and a boiling point> 100 ⁰ C as the core material lead to favorable results.

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. Depending on the preparation process and the selected protective colloid, this may also be part of the microcapsules. Thus, up to 15% by weight, preferably from 1 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. The average particle size of the capsules (Z agent determined by means of light scattering) is 0.5 to 50 μm, preferably 0.5 to 30 μm, in particular 0.5 to 10 μm. The weight ratio of capsule core to capsule wall is generally from 50:50 to 95: 5. Preferred is a core / wall ratio of 70:30 to 93: 7.

Lipophilic substances are compounds which have a solubility of less than 30 g / liter in water at 25 ^° C. and normal pressure. The lipophilic substances which are suitable according to the invention have a boiling point> 100 ^° C. and a melting point <120 ^° C., preferably <100 ^° C., in particular <80 ^° C.

Suitable lipophilic substances for the use according to the invention are, for example:

aliphatic hydrocarbon compounds such as saturated or unsaturated C2o-Cioo hydrocarbons which are branched or preferably linear, e.g. such as n-eicosane, n-heneicosane, n-docosane, n-tricosane, n-tetracosane, n-pentacosane, n-hexacosane, n-heptacosane, n-octacosane, n-nonacosane, n-tricontane, n-tetracontane, n Pentacontane, n-hexacontane, n-heptacontan, n-octacontan, n-nonacontan, n-hectan and cyclic hydrocarbons, eg Cyclooctane, cyclodecane;

aromatic hydrocarbon compounds such as naphthalene, biphenyl, o- or m-terphenyl, Ci-C4o-alkyl-substituted aromatic hydrocarbons

saturated or unsaturated C 12 -C 30 -fatty acids, such as lauric, palmitic, stearic or behenic acid, preferably eutectic mixtures of decanoic acid with e.g. Myristic, palmitic or lauric acid;

Fatty alcohols such as stearyl alcohol, myristyl alcohol, mixtures such as coconut fatty alcohol and the so-called oxo alcohols, which are obtained by hydroformylation of α-

Olefins and further reactions;

C6-C3o-fatty amines such as tetradecylamine, hexadecylamine or eicosylamine;

Esters, such as C 1 -C 10 -alkyl esters of fatty acids, such as stearyl stearate, and preferably their eutectic mixtures;

natural and synthetic waxes such as montan acid waxes, montan ester waxes, carnauba wax, polyethylene wax, oxidized waxes, polyvinyl ether wax, ethylene vinyl acetate wax or Fischer-Tropsch wax waxes.

Method; halogenated hydrocarbons such as chlorinated paraffin and bromodocosane.

Furthermore, mixtures of these substances are suitable.

For example, the use of n-alkanes having a purity of greater than 80% or of alkane mixtures, as obtained as a technical distillate and commercially available as such, is advantageous.

The capsule wall is preferably made of a thermosetting polymer. Under thermosetting wall materials are to be understood that do not soften due to the degree of crosslinking, but decompose at high temperatures. Suitable thermosetting wall materials are, for example, crosslinked formaldehyde resins, crosslinked polyureas, crosslinked polyurethanes and crosslinked methacrylic and acrylic ester polymers. Also suitable are uncrosslinked methacrylic and acrylic ester polymers.

Formaldehyde resins are understood as meaning reaction products of formaldehyde with

Triazines such as melamine carbamides such as urea

Phenols such as phenol, m-cresol and resorcinol

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

or their mixtures.

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

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

Capsule walls of polyureas and polyurethanes are also of the

Copier paper known here. The capsule walls are created by implementation of Nhb groups or OH-carrying reactants with di- and / or polyisocyanates. Suitable isocyanates are, for example, ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 4,4'-methylenebis (phenyl isocyanate) 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 Pat. Nos. 4,021,595, EP-A 0 392 876 and EP-A 0 535 384.

The capsule wall is preferably a polymer containing at least 30 wt .-%, preferably at least 40 wt .-%, and up to 100 wt .-%, preferably at most 90 wt .-%, in particular at most 85 wt .-% and completely more preferably at most 80 wt .-% of at least one monomer selected from the group comprising Ci-C24-alkyl esters of acrylic and methacrylic acid, acrylic acid, methacrylic acid and maleic acid (monomers I), copolymerized, based on the total weight of the monomers.

Furthermore, the polymers of the capsule wall preferably contain at least 10% by weight, preferably at least 15% by weight, preferably at least 20% by weight and generally at most 70% by weight, preferably at most 60% by weight and in particular more preferably Form at most 50 wt .-% of one or more bi- or polyfunctional monomers which are insoluble or sparingly soluble in water (monomers II), copolymerized, based on the total weight of the monomers.

In addition, the polymers may contain up to 40% by weight, preferably up to 30% by weight, in particular up to 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. 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. Generally, the methacrylates and methacrylic acid are preferred.

According to a preferred embodiment, the microcapsule walls are composed of 25% by weight to 75% by weight of maleic acid and / or acrylic acid, in particular methacrylic acid. Suitable monomers II are bi- or polyfunctional monomers which are insoluble or sparingly soluble in water but have good to limited solubility in the lipophilic substance. Low solubility is to be understood as meaning a solubility of less than 60 g / l at 20 ^° C. Bi- or polyfunctional monomers are understood to mean compounds which have 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.

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. Particularly preferred are propanediol, butanediol, pentanediol and hexanediol diacrylate and the corresponding methacrylates.

Preferred polyvinyl monomers are the polyesters of polyols with acrylic acid and / or methacrylic acid, furthermore the polyallyl and polyvinyl ethers of these polyols or trivinylcyclohexane and trivinylbenzene. 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, as well as hexanediol diacrylate 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. Especially preferred are monomers such as itaconic acid, vinylphosphonic acid, maleic anhydride, 2-hydroxyethyl acrylate and methacrylate, acrylamido-2-methylpropanesulfonic acid, methacrylonitrile, acrylonitrile, methacrylamide, N-vinylpyrrolidone, N-methylolacrylamide, N-methylolmethacrylamide, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate. Preferably, the capsule wall is constructed from

From 30 to 100% by weight, based on the total weight of the monomers, of one or more monomers (monomers I) selected from C ₁ -C ₂₄ -

Alkyl esters of acrylic and methacrylic acid, acrylic acid, methacrylic acid and maleic acid,

0 to 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)

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

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 the 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

Monomers Ib> 25 wt .-% based on the total weight of all

Monomers I, II and III are

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

The microcapsules suitable according to the invention can be prepared by a so-called in situ polymerization. The microcapsules and their preparation are known from EP-A-457 154, DE-A-10 139 171, DE-A-102 30 581 and EP-A-1 321 182, to which reference is expressly made. Thus, the microcapsules are prepared by preparing a stable oil-in-water emulsion from the monomers, a radical initiator, a protective colloid and the lipophilic substance to be encapsulated. Stable in this case means that there is no doubling of the average droplet size within one hour. Subsequently, the free-radical polymerization of the monomers is initiated by heating and controlled by further increase in temperature, wherein the resulting polymers form the capsule wall, which encloses the lipophilic substance.

In general, the polymerization is conducted at 40 to 150 ^° C, by preferably at 60 to 120 ^° C. Of course, the dispersion and polymerization temperature should be above the melting temperature of the lipophilic substances.

After reaching the final temperature, the polymerization is expediently continued for a time of up to 2 hours in order to lower residual monomer contents. Following the actual polymerization reaction at a conversion of 90 to 99% by weight, it is generally advantageous to make the aqueous microcapsule dispersions substantially free of odor carriers, such as residual monomers and other organic volatile constituents. This can be achieved physically in a manner known per se by distillative removal (in particular via steam distillation) or by stripping with an inert gas. Furthermore, it can be done chemically, as described in WO 9924525, advantageously by redox-initiated polymerization, as described in DE-A-4 435 423, DE-A-4419518 and DE-A-4435422.

It is possible in this way to produce microcapsules having an average particle size in the range from 0.5 to 100 .mu.m, it being possible to adjust the particle size in a manner known per se by means of the shearing force, the stirring rate, the protective colloid and its concentration. Preference for incorporation into hydraulically setting building material mixtures microcapsules having an average particle size in the range of 0.5 to 50 .mu.m, preferably 0.5 to 30 .mu.m, in particular 0.5 to 10 microns (Z means by light scattering).

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. Organic protective colloids are preferably water-soluble polymers, since they 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 microns, preferably 0.5 to 30 microns, in particular 0.5 to 10 microns, form.

Organic neutral protective colloids are, for example, cellulose derivatives such as hydroxyethylcellulose, methylhydroxyethylcellulose, methylcellulose and carboxymethylcellulose, polyvinylpyrrolidone, copolymers of vinylpyrrolidone, gelatin, gum arabic, xanthan, sodium alginate, 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.

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

Naphthalenesulfonic acid and naphthalenesulfonic acid-formaldehyde condensates and especially polyacrylic acids and phenolsulfonic acid-formaldehyde condensates.

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

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

The inorganic solid particles may be metal salts, such as salts, oxides and hydroxides of calcium, magnesium, iron, zinc, nickel, titanium, aluminum, silicon, barium and manganese. These include magnesium hydroxide, magnesium carbonate, magnesium oxide, calcium oxalate, calcium carbonate, barium carbonate, barium sulfate, titanium dioxide, aluminum oxide, aluminum hydroxide and zinc sulfide. Silicates, bentonite, hydroxyapatite and hydrotalcites are also mentioned. Particularly preferred are highly disperse silicas, magnesium pyrophosphate and tricalcium phosphate. The Pickering systems can both be added to the water phase first, as well as added to the stirred oil-in-water emulsion. Some fine, solid particles are produced by precipitation as described in EP-A-1 029 018 and EP-A-1 321 182.

The highly dispersed silicas can be dispersed as fine, solid particles in water. But it is also possible to use so-called colloidal dispersions of silica in water. 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.

Preference is given to using inorganic protective colloids, in particular Pickering systems, if appropriate mixed with organic protective colloids.

In another embodiment, organic neutral protective colloids are preferred. Particular preference is given to OH-bearing protective colloids such as polyvinyl alcohols and partially hydrolyzed polyvinyl acetates.

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

The microcapsule dispersions obtained by means of polymerization give, as described in WO 2006/092439, a free-flowing capsule powder when spray-dried. The spray desiccant and spray aids described therein are expressly incorporated by reference.

Microcapsules which are suitable according to the invention are described in more detail in EP-A 1 421 243, DE 101 63 162, WO 2005/116559 and WO 2006/092439, in particular in the context of the examples. The latent heat storage materials used in this case also show a solid / liquid phase transition in the required temperature range. For the latent heat storage materials, however, a high purity of the substances is additionally advantageous, since this leads to particularly good transformation enthalpies. As part of The present invention has shown that a high purity is not required, but especially an increased stability of the microcapsule in the mixing and curing process is advantageous, which is probably given by the solidified capsule core material.

The microcapsules can be incorporated as a powder, as a paste and as a microcapsule dispersion in the hydraulically setting building material mixture. In this case, it is advantageous to use the microcapsule dispersion obtained directly during production in order to save additional insulating steps.

By setting the building material mixture according to the invention gives a mineral molding. This is understood to mean that the shaped body of a mixture of cement, water, additives and, if appropriate, auxiliaries after shaping, is formed by hardening the cement-water mixture as a function of time, optionally under the effect of elevated temperature.

The aggregates are usually made of granular or fibrous, natural or artificial rock (gravel, sand, glass or mineral fibers), in special cases also of metals or organic aggregates or mixtures of said aggregates, with particle sizes or fiber lengths that suit the intended use are adapted in a conventional manner. Frequently, for the purpose of coloring and colored pigments are also used as surcharges.

Suitable auxiliaries are, in particular, those substances which accelerate or retard the hardening or which influence the elasticity or porosity of the solidified mineral shaped body. These are in particular polymers, as z. From US-A 4 340 510, GB-PS 15 05 558, US-A 3 196 122, US-A 3 043 790, US-A 3 239 479, DE-A 43 17 035 DE-A 43 17 036, JP-A 91/131 533 and other documents are known.

The present invention further relates to hydraulically setting building material mixtures containing 0.1 to 5 wt .-% microcapsules based on cement, wherein the microcapsules comprises a capsule wall of polymer and a lipophilic substance as a capsule core, the melting point <120 ⁰ C and their boiling point> 100 ⁰ C. Based on a 40% strength by weight microcapsule dispersion, based on conventional concrete blocks, this means that from 0.1 to 3.5% by volume of the microcapsule dispersion is used to produce a m ³ concrete block.

Surprisingly, mineral moldings containing microcapsules with lipophilic substance as core materials show good frost / thaw stabilities. This is all the more surprising, since the capsules are filled and therefore do not have the required according to the theory gas cavities. Examples

Preparation of the microcapsule dispersions used according to the invention

Example 1 Water phase: 1298 g of water 662 g of a 5% strength by weight solution of methyl hydroxyethyl cellulose 165 g of a 10% strength by weight aqueous polyvinyl alcohol solution (degree of hydrolysis:

79%) Mowiol ^® 15-79

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

Oil phase 1532 g n-octadecane 68.3 g methyl methacrylate 68.3 g butanediol diacrylate 34.1 g methacrylic acid 2.44 g of a 75% strength by weight solution of t-butyl perpivalate in aliphatic acid.

hydrocarbons

Feed 1:

18.7 g of a 10% by weight aqueous t-butyl hydroperoxide solution

Feed 2:

98.5 g of a 1 wt .-% aqueous ascorbic acid solution

At room temperature, the above water phase was presented. After addition of the oil phase was dispersed with a high-speed dissolver at 3500 rpm. After 40 minutes of dispersion, a stable emulsion of particle size 2 to 12 microns in diameter was obtained. The emulsion was heated with stirring with an anchor raker in 60 minutes at 70 ⁰ C, within a further 60 minutes at 85 ⁰ C and held at 85 ⁰ C for one hour. Feed 1 was added to the resulting microcapsule dispersion with stirring. Feed 2 was metered in with stirring over 90 minutes while being cooled to room temperature. Then it was neutralized with sodium hydroxide solution. The resulting microcapsule dispersion had a solids content of 42% and an average particle size of 4.5 microns (measured with Fraunhoferbeugung, volume average).

Example 2 Water phase:

850 g of water

138 g of a 50% strength by weight, alkali-stabilized silica sol (specific surface area approx.

80 m ² / g) 25 g of a 1 wt .-% aqueous solution of methyl hydroxyethyl cellulose

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

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

Oil phase 550 g of a technical paraffin wax with a melting point of about 63 ° C.

103.1 g of methyl methacrylate

34.4 g of butanediol diacrylate

Addition 1 1.15 g of a 75% strength by weight solution of t-butyl perpivalate in aliphatic acid. hydrocarbons

Feed 1:

8.93 g of a 10 wt .-% aqueous t-butyl hydroperoxide solution

Feed 2:

35.5 g of a 1 wt .-% aqueous ascorbic acid solution

The water phase was initially introduced at 70 ^° C., into which the molten and homogeneously mixed oil phase was added and dispersed for 40 minutes with a high-speed dissolver stirrer (disk diameter 5 cm) at 3500 rpm. Addition 1 was added. The emulsion was heated with stirring with an anchor raker in 60 minutes at 70 ⁰ C, within a further 60 minutes at 85 ⁰ C and held at 85 ⁰ C for one hour. Feed 1 was added to the resulting microcapsule dispersion with stirring. Feed 2 was metered in with stirring over 90 minutes while being cooled to room temperature. Then it was neutralized with sodium hydroxide solution. A microcapsule dispersion having a mean particle size of 9.7 μm and a solids content of 43.6% was obtained.

Example 3

Water phase: 850 g of water 138 g of a 50% strength by weight, alkali-stabilized silica sol (specific surface area approx.

80 m ² / g) 25 g of a 1 wt .-% aqueous solution of methyl hydroxyethyl cellulose 2.6 g of a 2.5% strength by weight aqueous sodium nitrite solution

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

Oil phase 550 g diisopropylnaphthalene

103.1 g of methyl methacrylate

34.4 g of butanediol diacrylate

1, 15 g of a 75 wt .-% solution of t-butyl perpivalate in aliphatic.

hydrocarbons

Feed 1:

8.93 g of a 10 wt .-% aqueous t-butyl hydroperoxide solution

Feed 2: 35.5 g of a 1% strength by weight aqueous ascorbic acid solution

The aqueous phase was initially introduced at 40 ^° C., into which the oil phase was added and dispersed for 40 minutes with a high-speed dissolver stirrer (disc diameter 5 cm) at 3500 rpm. The emulsion was heated with stirring with an anchor raker in 60 minutes at 70 ⁰ C, within a further 60 minutes at 85 ⁰ C and held at 85 ⁰ C for one hour. Feed 1 was added to the resulting microcapsule dispersion with stirring. Feed 2 was metered in with stirring over 90 minutes while being cooled to room temperature. Then it was neutralized with sodium hydroxide solution. A microcapsule dispersion having an average particle size of 8.4 μm and a solids content of 43.6% was obtained.

Example 4

The procedure was as in Example 3 with the difference that the following

Water phase was used:

750 g of water

230 g of a 30% strength by weight, alkali-stabilized silica sol (average particle size about 30 nm) 25 g of a 1% strength by weight aqueous solution of methylhydroxyethylcellulose

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

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

A microcapsule dispersion having a mean particle size of 4.3 μm and a solids content of 43.2% was obtained.

Example 5 The procedure was as in Example 3 with the difference that the following oil phase was used:

539 g of a technical paraffin mixture with a melting point of about 26 ° C.

1 1 g of a paraffin with a melting point of about 65 ⁰ C.

103.1 g of methyl methacrylate 34.4 g of butanediol diacrylate

1, 15 g of a 75 wt .-% solution of t-butyl perpivalate in aliphatic. hydrocarbons

A microcapsule dispersion having an average particle size of 8.7 μm and a solids content of 44.0% was obtained.

Example 6

The procedure was as in Example 3 with the difference that the following

Oil phase was used:

539 g of n-dodecane 1 1 g of a paraffin with melting point of about 65 ⁰ C.

103.1 g of methyl methacrylate

34.4 g of butanediol diacrylate

1, 15 g of a 75 wt .-% solution of t-butyl perpivalate in aliphatic.

Hydrocarbons A microcapsule dispersion having a mean particle size of 9.7 μm and a solids content of 42.2% was obtained.

test methods

To determine the frost-thaw resistance of the cured concrete mixtures 1-3 described below in the examples, a test was carried out in accordance with ASTM 666C (Procedure A). After 2 weeks of curing, the concrete block was exposed to a defined number of freeze-thaw cycles and the development of the FT factor (strength of the stone normalized to the starting point) was observed over time. The starting point for the FT factor is set to 100 and it should not fall below 80 during the test for the test to pass. In addition, the weathering factor was determined. It is a qualitative measure of the optically visible damage to the concrete. For ratings from 0 = no frost damage (very good) to 5 = severe frost damage (very bad), the value should not be worse than 3. In addition to the freeze-thaw characterization, the air content and compressive strength of the concrete were determined after 7 and 28 days. Preparation of the hydraulically setting binder mixtures Concrete mixtures 1a, 1b and 1c

Concrete mixture 1 a (basic recipe - not according to the invention)

The recipe used corresponded to ordinary ready-mix concrete and contained 337 kg Ashgrove cement, 739 kg sand, 2370 kg aggregate and 172 kg water. These quantities refer to a m ³ concrete block.

Concrete mixture 1 b (not according to the invention)

In contrast to the basic formulation, 177 ml of water were passed through 177 ml of Micro Air ^® 70

(BASF Aktiengesellschaft, air entraining agent).

Concrete mixture 1 c (according to the invention)

In contrast to the basic formulation, 22.1 kg of the microcapsule dispersion of Example 1 were metered onto a m ³ concrete by replacing a quantity of water corresponding to this volume.

Examination of the hardened concrete block after 180 freeze-thaw cycles resulted in the following frost-thaw stability (FT factor), as well as the following weathering factor and compressive strengths.

* Air content in Vol% based on the volume of concrete block

The not inventive example 1 b shows that the entry of air bubbles leads to a good freeze-thaw stability, but leads to a poor compressive strength of the concrete block. In contrast, the concrete block according to the invention has both a good freeze-thaw stability and good compressive strength.

The microcapsule dispersions obtained according to Examples 2 to 6 can be used to produce concrete blocks with good freeze-thaw stabilities and good compressive strength analogously to ready-mixed concrete.

Concrete mixture 2a, 2b and 2c Concrete mixture 2a (basic recipe - not according to the invention) A self-compacting concrete (SVB) consisting of 417 kg Ashgrove cement, 830 kg sand, 2166 kg aggregate and 146 kg water was produced. To set the desired liquefaction, 3.8 kg were Glenium ^® 7500 (polycarboxylate; BASF Aktiengesellschaft) were used. These quantities refer to a m ³ concrete block.

Concrete mixture 2b (not according to the invention)

In contrast to the basic formula, 177 ml of water were replaced by 177 ml of Micro Air 70.

Concrete mixture 2c (according to the invention)

Deviating from the basic formulation, 33 kg of the microcapsule dispersion of Example 1 were metered onto a m ³ concrete by replacing a quantity of water corresponding to this volume.

^* Air content in% by volume based on the concrete block

With the microcapsule dispersions obtained according to Examples 2 to 6 concrete blocks with good freeze-thaw stabilities and good compressive strength can be produced analogously from self-compacting concrete.

Concrete mixture 3a, 3b and 3c

Concrete mixture 3a (basic recipe - not according to the invention)

A fly ash-containing ready-mixed concrete was produced from 268 kg Ashgrove cement, 67 kg fly ash, 745 kg sand, 2400 kg aggregate and 151 kg water. These quantities refer to a m ³ concrete block.

Concrete mixture 3b (not according to the invention) In contrast to the basic formula, 250 ml of water were replaced by 250 ml of Micro Air 70.

Concrete mix 3c (according to invention) Notwithstanding the basic formulation were 16.6 kg microcapsule dispersion of Example 1 dosed at a m ³ of concrete, in that a corresponding volume of this amount of water was replaced.

^* Air content in% by volume based on the concrete block

With the microcapsule dispersions obtained according to Examples 2 to 6 concrete blocks with good freeze-thaw stabilities and good compressive strength can be produced analogously from fly ash-containing transport concrete.

Claims

claims

1. Use of microcapsules comprising a capsule wall made of polymer and a lipophilic substance as a capsule core, which has its melting point <120 ⁰ C and its boiling point> 100 ⁰ C, as a frost-thaw stability additives in hydraulically setting building material mixtures.

2. Use according to claim 1, characterized in that the lipophilic substance is selected from aliphatic hydrocarbon compounds, aromatic hydrocarbon compounds, saturated or unsaturated C12-

C3o-fatty acids, fatty alcohols, Cβ-Cso-fatty amines, esters of fatty acids, natural waxes, synthetic waxes and halogenated hydrocarbons.

3. Use according to claims 1 or 2, characterized in that the capsule wall is constructed from

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

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

4. Use according to one of claims 1 to 3, characterized in that the capsule wall is constructed from

30 to 100 wt .-% of a mixture of monomers Ia and Ib, wherein the proportion of the monomers Ib <25 wt .-% based on the total weight of all monomers I, II and III,

10 to 70 wt .-% of a mixture of divinyl and polyvinyl monomers (monomers II), wherein the proportion of polyvinyl monomers 2 to 90 wt .-% based on the monomers II and 0 to 30 wt .-% based on the total weight of Monomers, one or more other monomers (monomers III) in each case based on the total weight of the monomers.

5. Use according to one of claims 1 to 3, characterized in that 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 wt .-% 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

Wt .-% based on the monomers II and

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

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

6. Use according to any one of claims 1 to 5, characterized in that the microcapsules are obtainable by radical polymerization of an oil-in-water emulsion containing the monomers, the lipophilic substance and a protective colloid.

7. Use according to one of claims 1 to 6, characterized in that the microcapsules are obtainable by radical polymerization of an oil-in-water emulsion containing the monomers, the lipophilic substance and a pinning system as a protective colloid.

8. Use according to one of claims 1 to 7, characterized in that one mixes the microcapsule dispersion obtained after the capsule wall formation with cement, water, aggregates and optionally excipients.

9. Use according to one of claims 1 to 8, characterized in that 0.1 to 5 wt .-% microcapsules are used based on cement.

10. Hydraulically setting building material mixtures containing 0.1 to 5 wt .-% micro- capsules according to any one of claims 1 to 9 based on cement.