WO2008145533A1

WO2008145533A1 - Method for producing insulating coatings

Info

Publication number: WO2008145533A1
Application number: PCT/EP2008/055961
Authority: WO
Inventors: Martin Wagner; Christian HÖGL
Original assignee: Wacker Chemie Ag
Priority date: 2007-05-30
Filing date: 2008-05-15
Publication date: 2008-12-04
Also published as: DE102007024963A1

Abstract

The invention relates to a method for producing insulating coatings by drying aqueous coating compounds containing binders, fillers, and optionally further additives, at a temperature between 80 and 250°C, characterized in that the aqueous coating compounds comprise one or more hydrophobized silicic acids.

Description

Process for the preparation of insulating coatings

The invention relates to a process for the production of insulating coatings, to the process products obtainable therewith and to their use in particular for heat or sound insulation.

Insulating coatings usually consist of binders, fillers and optionally further additives (coating composition) and usually have one

Layer thickness of at least 0.3 mm. As binders polymers are often used. Essentially two methods are used to produce the insulating coatings. On the one hand, curable, liquid coating compositions can be used which, after application to a substrate, are cured and thereby converted into a solid, insulating coating. The dissolution, emulsification or suspension of the components of the coating compositions is usually achieved by using liquid, curable binders. However, this method is not very flexible because the choice of individual components and their proportion of the coating composition must be aligned with the coating composition being in a liquid form. The optimization of the properties of the insulating coatings by changing the coating composition is possible in this way only to a very limited extent.

In another method, insulating coatings are prepared by coating, emulsifying or dispersing coating compositions dissolved in solvents onto the substrates and then removing the solvents. The solvents used are both organic solvents and water. The use of water is associated with considerable advantages for ecological, economic and safety reasons.

However, the drying of aqueous coating compositions causes great problems, especially when insulating Stratifications are made with high layer thicknesses. If the drying is carried out at temperatures well below the boiling point of water, the drying process takes an unacceptably long time. For example, JP63-43976 describes the drying of a coating composition at room temperature, which required 14 days. When the aqueous coating composition is dried in the boiling range of water, the surface of the aqueous coating compositions tends to be rapidly microfiltered so that further water vapor is trapped and the filmed surface is raised. In this way, eventually arise insulating coatings containing large air pores and are bloated. The surface of such insulating coatings is so heavily modeled and has mountains and valleys. Thus, available insulating coatings are unusable for applications because such inhomogeneities have a negative effect on the properties of the insulating coatings and interfere with the application of further coatings or components.

So far, the o.g. The problem with drying aqueous coating compositions was circumvented by mixing the aqueous coating compositions with a view to optimizing their drying behavior. However, this approach has the disadvantage that the individual components of the coating compositions can not be selected and blended according to the application requirements.

Against this background, the object was to provide a widely applicable method for the production of insulating coatings, in which the problems described above do not occur in the drying of aqueous coating compositions in the boiling range of water.

The object was surprisingly achieved by adding hydrophobized silicic acids to the aqueous coating compositions. The invention relates to a method for producing insulating coatings by drying of aqueous coating compositions comprising the binder, Füllstof- fe and optionally further additives at a temperature between 80 and 250 ⁰ C, characterized in that the aqueous coating compositions of one or more hy- contain hydrophobized silicic acids.

For the inventive method are suitable from the

Prior art known hydrophobized silicas, as they are known for example from EP0686676 Al. The hydrophobized silicas are obtainable, for example, by silylation of silicas with one or more silylating agents, preferably volatile silylating agents, or silylating agents which can be atomized as finely divided aerosol. The silicas may be obtained by wet-chemical precipitation or pyrogenically by flame hydrolysis, e.g. of tetrachlorosilane. Preference is given to pyrogenically prepared, highly disperse silicas which, as described, for example, in DE 26 20 737 or DE 42 21 716, are produced pyrogenically from silicon halogen compounds.

Suitable silylating agents are, for example, one or more organosilicon compounds. Organosilicon compounds are preferably organosilanes of the general formula R ¹ HSiX ₄ -H (I) in which

R ^{1 may be the} same or different and is a monovalent, optionally halogenated, hydrocarbon radical having 1 to 18 C atoms,

X may be identical or different and halogen, preferably chlorine, a nitrogen radical or OH, OR ² , OCOR ² , O (CH ₂ ) _X OR ² , R ^{2 may be} identical or different and a monovalent hydrocarbon radical having 1 to 8 carbon atoms n is 1, 2 or 3, preferably 2 and x is 1, 2 or 3, preferably 1, and / or organosiloxanes containing one or more units selected from the group comprising (R3SiO] _ / 2), ( ^R 2SiC> 2/2) '(RSiO3 / 2), (X3SiO] _ / 2), (RX2SiOi / 2) and (R2XSiO] _ / 2), wherein X has the meaning given above and R has the meanings given above for R ¹ or R ² or represents a hydrogen atom.

Preferred are organosiloxanes of the general formula

x (R ³ R ¹ SiO ₂₇₂ ) _y (SiX _b R ¹ _a ) _z (II), in which R ^{1 has} the meaning given above,

R ^{2 has} the meaning given above,

R ^{3 may be} identical or different, is a hydrogen and a monovalent, optionally halogenated ter, hydrocarbon radical having 1 to 18 C atoms other than R ¹ , X has the meaning given above, preferably OH, a is 0, 1 , 2 or 3, preferably 2, b is 0, 1, 2 or 3, preferably 1, wherein the sum a + b is 3, x is 0 or an integer from 1 to 200, preferably 10 to 50, y is the same 0 or an integer from 1 to 200, preferably x to y at least equal to 5 to 1 and the sum x + y is 0 or an integer between 1 and 200, preferably 10 to 50, z is 0 or 1, with with the proviso that z is greater than 0 if the sum x + y is equal to 0, then z is equal to 1.

The preparation of the organosilanes and organosiloxanes has been described many times and is carried out according to generally known preparation processes.

Examples of R ¹ are alkyl radicals such as the methyl radical, the ethyl radical, propyl radicals such as the iso- or n-propyl radical, butyl radicals such as the t- or n-butyl radical, pentyl radicals such as the neo, iso or n Pentyl radical, hexyl radicals such as n-

Hexyl radical, heptyl radicals such as the n-heptyl radical, octyl radicals such as the 2-ethylhexyl or the n-octyl radical, decyl radicals such as the n-decyl radical, dodecyl radicals such as the n-dodecyl radical, hexadecyl radicals such as the n-hexadecyl radical, octadecyl radicals such as the n-octadecyl radical, alkenyl radicals such as the vinyl, the 2-allyl or the 5-hexenyl radical, aryl radicals such as the phenyl, the biphenyl or the naphthyl radical, alkylaryl radicals such as benzyl, ethylphenyl , Toluyl or the xylyl radicals, halogenated alkyl radicals such as 3-chloropropyl, 3,3,3-trifluoropropyl or perfluorohexylethyl, halogenated aryl radicals such as the chlorophenyl or chlorobenzyl radical. Preferred for R ¹ are the methyl radical, the ethyl radical, propyl radicals such as the iso or n-propyl radical, butyl radicals such as the t- or n-butyl radical. Particularly preferred is the methyl radical.

Examples of R ² are alkyl radicals such as the methyl radical, the ethyl radical, propyl radicals such as the iso- or n-propyl radical, butyl radicals such as the t- or n-butyl radical, pentyl radicals such as the neo, iso or n -Pentyl radical, hexyl radicals such as the n-hexyl radical, heptyl radicals such as the n-heptyl radical, octyl radicals such as the 2-ethylhexyl or the n-octyl radical. Preferred for R ² are the methyl, ethyl and propyl radical. Particularly preferred is the methyl radical.

Examples of R ³ are alkyl radicals such as the methyl radical, the ethyl radical, propyl radicals such as the iso- or n-propyl radical, butyl radicals such as the t- or n-butyl radical, pentyl radicals such as the neo, iso or n Pentyl radical, hexyl radicals such as n-

Hexyl radical, heptyl radicals such as the n-heptyl radical, octyl radicals such as the 2-ethylhexyl or the n-octyl radical, decyl radicals such as the n-decyl radical, dodecyl radicals such as the n-dodecyl radical, hexadecyl radicals such as the n-hexadecyl radical, octadecyl radicals such as the n- Octadecyl radical, alkenyl radicals such as the vinyl, the 2-allyl or the 5-hexenyl radical, aryl radicals such as the phenyl, the biphenyl or naphthyl radical, alkylaryl radicals such as benzyl, ethylphenyl, toluyl or the xylyl radicals, halogenated alkyl radicals such as 3-chloropropyl, the 3, 3, 3-trifluoropropyl or the Perfluorhexy- lethylrest, halogenated aryl radicals such as chlorophenyl or

Chlorobenzyl. Preference is given to n-octyl, n-octadecyl, vinyl and 3, 3, 3-trifluoropropyl. Particularly preferred is the n-octyl radical. Examples of organosilanes according to formula I are Methyltrichlor- silane, dimethyldichlorosilane, trimethylchlorosilane, methyl trimethoxysilane, dimethyldimethoxysilane, Trimethylmethoxysi- lan, methyltriethoxysilane, dimethyldiethoxysilane, trimethylol lethoxysilan, Methyltriacethoxysilan, Dimethyldiacethoxysilan, Trimethylacethoxysilan, octylmethyldichlorosilane, Octyltrich- lorsilan, octadecylmethyldichlorosilane, octadecyltrichlorosilane, vinyltrichlorosilane , Vinylmethyldichlorosilane, vinyldimethylchlorosilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, hexamethyldisilazane, divinyltetramethyldisilazane, bis (3,3-trifluoropropyl) -tetra methyldisilazane, octamethylcyclotetrasilazane, trimethylsilanole. Preference is given to dialkylsilanes, particular preference being given to dialkyldichlorosilanes, such as dimethyldichlorosilane, octylmethyldichlorosilane and octadecylmethyldichlorosilane, and dimethyldimethoxysilane and dimethyldiethoxysilane. Most preferred is dimethyldichlorosilane.

For the preparation of the hydrophobized silicas, it is also possible to use any desired mixtures of organosilanes in any mixing ratios. In this case, preference is given to those mixtures in which, in accordance with formula I, compounds with n = 2 with ≥ 80 mol%, preferably ≥ 90 mol%, are present. Mixtures in which at least one compound according to formula I in which R is different, e.g. a methyl group and an alkyl group having at least 6 C atoms. Preference is given here to mixtures of dimethyldichlorosilane and octylmethyldichlorosilane in a ratio of from 5: 1 to 50: 1.

Examples of organosiloxanes are linear or cyclic dialkylsiloxanes having an average number of dialkylsiloxy units of greater than 3, particularly preferably from 5 to 100

Dialkylsiloxanes are preferably dimethylsiloxanes. Particular preference is given to linear polydimethylsiloxanes having the following end groups: trimethylsiloxy, dimethylhydroxysiloxy, dimethylchloro chlorosiloxy, methyldichlorosiloxy, dimethylmethoxysiloxy, methyldimethoxysiloxy, dimethylethoxysiloxy, methyldiethoxysiloxy, dimethylacethoxysiloxy, methyldiacethoxysiloxy, dimethylhydroxysiloxy, where the end groups may be the same or different. Particularly preferred among the above-mentioned polyvinyl lydimethylsiloxanen those having a viscosity at 25 ⁰ C of 2 to 100 mPas, and with the end groups trimethylsiloxy or di- methylhydroxysiloxy. Also suitable are any mixtures in any mixing ratios of the mentioned organosiloxanes.

Particular preference is given to silylating agents or silylating agent mixtures of the formulas I and II which on the hydrophobicized silica lead to occupancy with hydrocarbylsiloxy groups which are at least 80 mol%, preferably at least 90 mol% and particularly preferably at least 98 Mo1% have siloxy groups which are substituted by two hydrocarbon radicals, preferably dialkylsiloxy groups, particularly preferably dimethylsiloxy groups.

In a preferred embodiment, the organosilicon compounds of the formula (I) and of the formula (II) used as silylating agents are each a single type of organosilane of the formula (I) and a single type of organopolysiloxane of the formula (II) also a mixture of at least two different types of organosilane according to formula (I) and a mixture of at least two different types of organosiloxane according to formula (II) or one kind of organosilane of formula (I) and a mixture of Organosiloxane of the formula (II) or a mixture of the organosilane of the formula (I) and a kind of organosiloxane of the formula (II).

In the silylation of the silicas, preferably 0.5 to 100 parts by weight, more preferably 1 to 50 parts by weight, and most preferably 2 to 20 parts by weight of silylating agent are used, each based on 100 parts by weight of silica. The hydrophobicized silica preferably has an average primary particle particle size of ≦ 1000 nm, particularly preferably an average primary particle particle size of 2 to 100 nm, most preferably an average primary particle particle size of 5 to 50 nm, these primary particles not being present in isolation, but instead Components of larger aggregates (definition according to DIN 53206), which have a diameter of 80 to 800 nm and agglomerates (definition according to DIN 53206) build, depending on the outer

Shear stress sizes of 1 to 500 microns have. The hydrophobized silica preferably has a specific surface area of ≥ 25 m ² / g, particularly preferably from 30 to 500 m ² / g, most preferably from 50 to 400 m ² / g (measured according to the BET method according to DIN 66131 and 66132). on. The hydrophobized silica has a carbon content of ≥ 0.1 wt%, more preferably from 0.25 wt% to 15 wt%, most preferably from 0.5 wt% to 10.0 wt. -% on. The hydrophobized silica preferably has a methanol number of ≥ 20, more preferably 25, most preferably 30. The silylating agent on the hydrophobized silica is preferably completely fixed chemically and preferably has no extractable from the hydrophobized silica or soluble fraction.

Preference is given to a hydrophobized silica in which at least 80 mol% of the silylating agent of the bound silylating agent consists of siloxy groups which are substituted by two hydrocarbon radicals.

The hydrocarbon radicals are preferably the radicals R ¹ and R ³ , which have the meaning given above.

Preferred binders are polymers based on one or more ethylenically unsaturated monomers selected from the group consisting of vinyl esters of carboxylic acids having 1 to 15 carbon atoms, methacrylic acid esters or acrylic acid esters of carbohydrates. bonsäuren with unbranched or branched alcohols having 1 to 15 carbon atoms, olefins or dienes, vinyl aromatics or vinyl halides.

Preferred vinyl esters are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate, vinyl pivalate and vinyl esters of alpha-branched monocarboxylic acids having 5 to 13 C atoms, for example VeoVa9R or VeoValOR (cf. Trade name of the company Shell). Especially preferred is vinyl acetate.

Preferred methacrylic esters or acrylic esters are esters of unbranched or branched alcohols having 1 to 15 C atoms, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, norbornyl acrylate Particularly preferred are methyl acrylate, methyl methacrylate, n-butyl acrylate and 2-ethylhexyl acrylate.

Preferred olefins or dienes are ethylene, propylene and 1,3-butadiene. Preferred vinylaromatics are styrene and vinyltoluene. A preferred vinyl halide is vinyl chloride.

Optionally, from 0.05 to 50 wt .-%, preferably 1 to 10 wt .-%, based on the total weight of the polymer, auxiliary monomers are copolymerized. Examples of auxiliary monomers are ethylenically unsaturated mono- and dicarboxylic acids, preferably acrylic acid, methacrylic acid, fumaric acid and maleic acid; ethylenically unsaturated carboxylic acid amides and nitriles, preferably acrylamide and acrylonitrile; Mono- and diesters of fumaric acid and maleic acid, such as diethyl and diisopropyl esters, and also maleic anhydride, ethylenically unsaturated sulfonic acids or salts thereof, preferably vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid. Further examples are precrosslinking comonomers such as multiply ethylenically unsaturated comonomers, for example divinyl adipate, diallyl maleate, allyl methacrylate or triallyl cyanurate, or post-crosslinking comonomers, for example acrylamidoglycol acid (AGA), methyl acrylamidoglycolic acid methyl ester (MAGME), N-methylolacrylamide (NMA), N-methylolmethacrylamide (NMMA), N-methylolallyl carbamate, alkyl ethers such as the isobutoxy ether or esters of N-methylolacrylamide, N-methylolmethacrylamide and N-methylolallylcarbamate. Also suitable are epoxide-functional comonomers such as glycidyl methacrylate and glycidyl acrylate. Further examples are silicon-functional comonomers, such as acryloxypropyltri (alkoxy) and methacryloxypropyltri (alkoxy) silanes, vinyltrialkoxysilanes and vinylmethyldialkoxysilanes, where the alkoxy groups which may be present are, for example, methoxy, ethoxy and ethoxypropylene glycol ether radicals. Mention may also be made of monomers having hydroxy or CO groups, for example methacrylic acid and acrylic acid hydroxyalkyl acrylates, such as hydroxyethyl, hydroxypropyl or hydroxybutyl acrylate or methacrylate, and also compounds such as diacetone acrylamide and acetylacetoxyethyl acrylate or methacrylate. Further examples are also vinyl ethers, such as methyl, ethyl or isobutyl vinyl ether.

Examples of suitable homopolymers and copolymers are vinyl acetate homopolymers, copolymers of vinyl acetate with ethylene, copolymers of vinyl acetate with ethylene and one or more further vinyl esters, copolymers of vinyl acetate with ethylene and acrylic esters, copolymers of vinyl acetate with ethylene and vinyl chloride, Styrene-acrylic acid ester copolymers, styrene-1,3-butadiene copolymers.

Preference is given to vinyl acetate homopolymers; Copolymers of vinyl acetate with 1 to 40% by weight of ethylene; Copolymers of vinyl acetate with 1 to 40 wt .-% of ethylene and 1 to 50 wt .-% of one or more other comonomers from the group of vinyl esters having 1 to 12 carbon atoms in the carboxylic acid radical such as vinyl propionate, vinyl laurate, vinyl esters of alpha-branched Carboxylic acids having 5 to 13 C atoms, such as VeoVa9R, VeoValOR, VeoVallR; Copolymers of vinyl acetate, 1 to 40 wt .-% of ethylene and preferably 1 to 60 wt .-% of acrylic acid esters of unbranched or branched alcohols with 1 to 15 C atoms, in particular n-butyl acrylate or 2-ethylhexyl acrylate; and copolymers having 30 to 75 wt .-% vinyl acetate, 1 to 30 wt .-% vinyl laurate or vinyl ester of an alpha-branched carboxylic acid having 5 to 13 carbon atoms, and 1 to 30 wt .-% acrylic acid esters of unbranched or branched alcohols 1 to 15 carbon atoms, especially n-butyl acrylate or 2-ethyl-ihexyl-iacrylat, which may contain 1 to 40 wt .-% of ethylene; Copolymers with vinyl acetate, 1 to 40% by weight of ethylene and 1 to 60% by weight of vinyl chloride; wherein the polymers may each still contain the said auxiliary monomers in the stated amounts, and the information in wt .-% add up to each 100 wt .-%.

Also preferred are (meth) acrylic acid ester polymers, such as copolymers of n-butyl acrylate or 2-ethylhexyl acrylate or copolymers of methyl methacrylate with n-butyl acrylate and / or 2-ethylhexyl acrylate and optionally ethylene; Styrene-acrylic acid ester copolymers with one or more monomers from the group of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate; vinyl acetate

Acrylic acid ester copolymers with one or more monomers from the group of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate and optionally ethylene; Styrene-1,3-butadiene copolymers; wherein the polymers can still contain said auxiliary monomers in the said amounts, and adding the data in wt .-% to each 100 wt .-%.

The monomer selection or the selection of the weight proportions of the comonomers is carried out such that in general a glass transition temperature Tg of -50 ⁰ C to +50 ⁰ C, preferably -30 ⁰ C to +40 ⁰ C results. The glass transition temperature Tg of the polymers can be determined in a known manner by means of differential scanning calorimetry (DSC). The Tg can also be approximated by the Fox equation. After Fox TG, Bull. Am. Physics Soc. 1, 3, page 123 (1956): l / Tg = xl / Tgl + x2 / Tg2 + ... + xn / Tgn, where xn represents the mass fraction (wt .-% / 100) of the monomer n, and Tgn the glass Transition temperature in Kelvin of the homopolymer of the monomer n. Tg values for homopolymers are listed in Polymer Handbook 2nd Edition, J. Wiley & Sons, New York (1975).

The polymers are prepared by the emulsion, suspension, solvent or bulk polymerization processes known to those skilled in the art, for example as described in DE-A 102006050336. The polymers are obtained in the form of aqueous dispersions and can be converted by customary drying methods to give corresponding water-redispersible powders.

Examples of suitable fillers are calcite, clay, barite, dolomite, silicates, vermiculite, talc, mica, slate flour, montmorillonite, glass or metal flakes, coal, coke, graphite, talc, clay minerals, magnesium hydroxide, magnesium sulfate heptahydrate, alum, Hydrargillite or metal oxides, such as Alumina, calcium oxide, zinc oxide, titanium dioxide or silicon dioxide, with baryte, calcite or mica being preferred.

Typical formulations for the aqueous coating compositions contain from 0.1 to 10% by weight, in particular from 0.5 to 3% by weight of hydrophobicized silica, from 0.5 to 50% by weight, in particular from 5 to 40% by weight. % Polymer as binder, 40 to

99.4% by weight, in particular 60 to 95% by weight of fillers, up to 10% by weight of additives such as, for example, dispersing aid, e.g. based on polyacrylates or polyphosphates, adhesion promoters, thixotropic agents, accelerators, stabilizers, pigments, water repellents, biocides or corrosion inhibitors. The data in% by weight relate to 100% by weight of the components of a formulation. The aqueous coating compositions contain 10 to 400 wt .-%, preferably 20 to 100 wt .-% water based on the total mass of the components of the recipe.

For the preparation of the aqueous coating compositions, for example, the hydrophobized silica, the Fillers and optionally the additives are added to the aqueous dispersions of the polymers before or during their drying so that the aqueous coating compositions are obtained in the form of water-redispersible powders which are redispersed at a later time with water.

Alternatively, to prepare the aqueous coating compositions, the individual components of the formulation are stirred into water simultaneously or sequentially or a mixture of all components of the formulation. Preferably, the individual components of the formulation are first mixed and dispersed at a later time with the amount of water specified in the recipe.

Also preferably, first the solid components of the formulation are mixed and then the liquid components of the recipe and water are added.

Particularly preferably, the binder is introduced in the form of an aqueous dispersion and mixed with stirring with the other components of the formulation.

For mixing the individual components of the coating composition, the stirrer and mixer familiar to the person skilled in the art are suitable, for example kneaders or stirred mixers.

Preferably, the aqueous coating composition has a viscosity of ≥ 10000 mPas, preferably from 30,000 mPas to 100,000 mPas (Brookfield, 23 ^° C., shear 20 rpm). By increasing the viscosity of the aqueous coating composition, any segregation of the aqueous coating composition, in particular a possible separation of the hydrophobicized silica, can be prevented.

The aqueous coating compositions may be, for example, by spraying, spraying, such as by high pressure spraying, troweling, brushing or knife coating the substrates are applied. Preferred substrates are plastic bodies or metal sheets, such as steel, aluminum.

The aqueous coating compositions have advantageous performance properties. Thus, the aqueous coating compositions have shear thinning rheological properties, as required in most applications. Shear thinning rheological compositions are sheared, i. using pressure, easy to transport and process. However, without shear, shear thinning rheological compositions are highly viscous and no longer flowable, so they have high stability on their substrate.

The drying of the aqueous coating composition on the substrate is preferably carried out at temperatures from 90 to 250 ⁰ C, particularly preferably from 100 to 250 ⁰ C and most preferably from 140 to 200 ⁰ C. The water ser of the aqueous coating composition is evaporated by drying , whereby the insulating coating is formed. Drying takes place in standard ovens or by irradiation with infrared radiation or microwaves.

Another object of the invention are insulating coatings obtainable by drying aqueous coating compositions containing binders, fillers and optionally further additives at a temperature between 80 and 250 ° C, characterized in that the aqueous coating compositions comprise one or more hydrophobized silicic acids.

The insulating coatings thus obtainable have a layer thickness of preferably at least 0.3 mm, more preferably from 0.3 to 30 mm, very preferably from 0.5 to 5 mm, most preferably from 1 to 5 mm. The insulating coatings have flat, flat surfaces. The surfaces of the insulating coatings are therefore not modeled by large, located in the insulating coatings air bubbles. The insulating coatings are characterized by a homogeneous composition.

Furthermore, the insulating coatings have advantageous performance properties. Thus, the adhesion of the insulating coatings on the substrate and the inter-adhesion between the components of the insulating coatings is very uniform and has no disturbances. In addition, the insulating coatings are evenly recoatable.

The insulating coatings are particularly suitable for thermal insulation or sound insulation. The insulating coatings can also be used for corrosion protection.

The following examples are given to illustrate the invention in detail and are in no way to be considered as limiting.

Production of the insulating coatings:

Example 1 (Example 1): In a 500 ml plastic beaker, 77.94 g of barite C14 (trade name from Sachtleben Bergbau), 38.46 g of an aqueous dispersion of a styrene-ethylhexyl acrylate copolymer (FG = 52%; = 0 ⁰ C) and 2.00 g HDK H15 (surface modification with -OSi (CHs) 2 ~, 0.9 carbon content wt .-%; submitted trade name of Wacker Chemie) and having a wide metal spatula for 3 minutes under normal conditions after DIN50014 evenly mixed. Then, with stirring, a solution of 0.06 g of polyacrylic acid salt in 25 g of water was added in 5 equal portions, and after stirring for further 3 minutes, the aqueous coating composition was obtained. There was a steel frame (length / width / height = 5Omm / 5Omm / 3mm) on an aluminum foil or in a second series on the release paper GP I 65 SOO. XX (trade name Mondi Packaging Release Liner Austria) and filled to the top of the frame with the aqueous coating composition completely. Then the frames were removed. By drying for 30 min at 160 ^° C. in a circulating-air drying oven (manufacturer: Binder), insulating coatings having planar surfaces and layer thicknesses of 3.0 mm were obtained.

Example 2 (Example 2)

In a 500 ml plastic beaker, 77.94 g of the o.

Barite, 37.11 g of an aqueous dispersion of polyvinyl acetate (FG = 53.9%, Tg = 44 ⁰ C) and 2.00 g HDK presented H15 and uniformly mixed with a broad metal spatula for 3 min under normal conditions according to DIN50014. Then, with stirring, a solution of 0.06 g of polyacrylic acid salt in 21 g of water was added in 5 equal portions, and after further stirring for 3 minutes, the aqueous coating composition was obtained. The preparation of the insulating coating was carried out analogously to the procedure described in Example 1. Insulating coatings with planar surfaces and layer thicknesses of 3.2 mm were obtained.

Example 3 (Example 3)

In a 500 ml plastic cup 77.94 g of the above-mentioned barite, 20.00 g of a vinyl acetate-ethylene copolymer in the form of a water-redispersible powder (Tg = -7 ° C) and 2.00 g HDK H15 presented and with a wide metal spatula evenly mixed for 3 min under normal conditions according to DIN50014. Then, with stirring, a mixture of 0.06 g of polyacrylic acid salt in 43 g of water was added in 5 equal portions, and after further stirring for 3 minutes, the aqueous coating composition was obtained. The preparation of the insulating coating was carried out analogously to the procedure described in Example 1. It were obtained insulating coatings with planar surfaces and layer thicknesses of 3.1 mm.

Example 4 (Example 4) The procedure was analogous to Example 3, but instead of 2.00 g of HDK H15, 2.00 g of HDK H 2 O (surface modification with - OSi (CH 3) 2 -, carbon content 1.4% by weight; Trade name of the company Wacker Chemie) and instead of 43 g of water, 50 g of water were used. Insulating coatings with planar surfaces and layer thicknesses of 3.0 mm were obtained.

Example 5 (Example 5)

The procedure was analogous to Example 3, but instead of 2.00 g HDK H15, 2.00 g HDK H30 (surface modification with - OSi (CH ₃ ) ₂ -, carbon content 1.8% by weight, trade name of Wacker Chemie) and instead of 43 g of water, 50 g of water were used. Insulating coatings with planar surfaces and layer thicknesses of 3.2 mm were obtained.

Example 6 (Example 6)

The procedure was analogous to Example 3, but instead of 77.94 g of barite, 77.94 g of calcite MS 80 (Schön & Hippelein) and instead of 43 g of water 57 g of water were used. Insulating coatings with slightly curved surfaces were obtained.

Example 7 (Example 7)

The procedure was analogous to Example 3, but instead of 77.94 g of barite, 77.94 g of muscovite mica were used and instead of 43 g of water, 90 g of water were used. There were obtained insulating coatings with planar surfaces and layer thicknesses of 3, 1 mm.

Comparative Example 1 (Vbsp. 1) A mixture of 38.46 g of an aqueous dispersion of styrene was added to 77.94 g of barite in a 500 ml plastic beaker while stirring with a wide metal spatula under standard conditions according to DIN50014 in 5 equal portions. Ethylhexylacrylat copolymerisat (FG = 52%, Tg = 0 ⁰ C) and 0.06 g of polyacrylic acid salt given. After stirring for an additional 3 minutes, the aqueous coating composition was obtained. The preparation of the insulating coating was carried out analogously to the procedure described in Example 1. There were obtained insulating coatings with strongly curved surfaces.

COMPARATIVE EXAMPLE 2 (VBsp. 2) To 77.94 g of barite in a 500 ml plastic beaker, a mixture of 37.11 g of an aqueous dispersion of polyvinyl acetate (FG = 53.9%, Tg = 44 ^° C) and 0.06 g of polyacrylic acid salt. After stirring for an additional 3 minutes, the aqueous

Coating composition obtained. The preparation of the insulating coating was carried out analogously to the procedure described in Example 1. There were obtained insulating coatings with strongly curved surfaces.

Comparative Example 3 (VBsp. 3)

The procedure was analogous to Example 3, but 17 g of water were used instead of 43 g of water and no HDK H 15 was added. Insulating coatings with strongly curved surfaces were obtained.

Comparative Example 4 (VBsp. 4)

The procedure was analogous to Example 6, but instead of 57 g of water, 25 g of water were used, and no HDK H 15 was added. There were obtained insulating coatings with strongly curved surfaces.

Comparative Example 5 (VBsp. 5)

The procedure was analogous to Example 7, but instead of 90 g of water, 60 g of water were used, and no HDK H 15 was added. There were obtained insulating coatings with strongly curved surfaces. Comparative Example 6 (VBsp. 6)

The procedure was analogous to Example 3, but instead of 2.00 g of HDK H 15, 2.00 g of HDK N 20 (not hydrophobic, 200 m ² / g of BET specific surface area, trade name of Wacker Chemie) and 43 g of water instead 30 g of water were used. There were obtained insulating coatings with strongly curved surfaces.

Comparative Example 7 (Example 7) The procedure was analogous to Example 3, but instead of 2.00 g of HDK H 15, 2.00 g of HDK V 15 (non-hydrophobic, 150 m ² / g of BET specific surface area, commercial name of Wacker Chemistry) and instead of 43 g of water, 25 g of water were used. Insulating coatings with strongly curved surfaces were obtained.

Testing

Determination of the planarity of the surface of the insulating coatings:

The planarity of the surface of the insulating coatings was determined visually with the following parameters: A = planar surface B = slightly curved surface C = strongly curved surface The results are summarized in Tables 1 and 2.

Determination of the compactness of the insulating coatings: It was a quotient Q from the maximum height of the insulating

Coating and the height of the steel frame formed for the production of the insulating coating. The corresponding quotients Q are listed in Tables 1 and 2.

Determination of the density of the insulating coating:

The release paper GP I 65 S00. XX was carefully removed completely from the respective insulating coating, so that the insulating coating material was not damaged. The Coating material was coated with the Dupli-Color Special two-coat clearcoat DC A2-03 (lacquer based on acrylate copolymers, trade name of the company Motip Dupli GmbH) with a layer thickness of about 150 μm. The density of the thus prepared insulating coating material was determined in accordance with DIN EN ISO 1183-1 with the aid of water. By sealing the coating material with the two-coat clearcoat, a displacement of the air contained in the coating material was prevented by water. The value of the density thus determined is thus directly dependent on the amount of air contained in the insulating coating and thus a direct measure of the air bubbles trapped in the coating. The corresponding values for the densities obtained with the insulating coatings of Examples 1 to 7 and Comparative Examples 1 to 7 are listed in Tables 1 and 2, respectively.

Table 1: Testing of the coating compositions of the examples:

Table 2: Testing of the coating compositions of Comparative Examples

The insulating coatings of Examples 1 to 3 (Table 1), all of which contain filler as sparger and hydrophobicized silica HDK H15 and in each case different binders, have densities of 1.21 g / ml to 1.98 g / ml and also very compact and flat surfaces (1.00 <Q <1.07, planarity: A). On the other hand, the corresponding insulating coatings of Comparative Examples 1 to 3 (Table 2), to which no hydrophobized silica has been added, have significantly lower densities and their surfaces are highly inflated and, accordingly, very uneven, as indicated by the corresponding quotient Q and planarity is expressed.

It can be seen from the tests of the insulating coatings of Examples 1, 7 and 8 (Table 1) that the process according to the invention is suitable for a wide range of different applications

Fillers is successfully applicable. In contrast, the corresponding insulating coatings have the comparative example 1, 4 and 5 show very low densities and very strongly curved surfaces (Table 2).

The results from Comparative Examples 6 and 7 show (Table 2) that with non-hydrophobized silicas only insulating coatings with very highly curved surfaces are available. In contrast, in the corresponding test series according to the invention of Examples 3, 4 and 6 with hydrophobized silicic acids, very homogeneous and plane-insulating coatings were obtained (Table 1).

The results recorded in Table 1 show that very homogeneous, plane and low-pore insulating coatings are obtained with the method according to the invention, even when using a wide variety of fillers, binders and hydrophobized silicas.

Claims

Claims:

1. A process for producing insulating coatings by drying aqueous coating compositions comprising binders, fillers and optionally further additives at a temperature between 80 and 250 ° C., characterized in that the aqueous coating compositions comprise one or more hydrophobized silicic acids.

2. The method according to claim 1, characterized in that the aqueous coating compositions have viscosity of> 10000 mPas (Brookfield, 23 ⁰ C, shear 20 U / min).

3. The method according to claim 1 to 2, characterized in that the aqueous coating compositions are applied by spraying, spraying, trowelling, brushing or doctoring on the substrates.

4. The method according to claim 1 to 3, characterized in that the aqueous coating compositions are applied to plastic body or metal sheets.

5. Insulating coatings obtainable by drying aqueous coating compositions containing binders, fillers and optionally further additives at a temperature between 80 and 250 ⁰ C, characterized in that the aqueous coating compositions contain one or more hydrophobized silicic acids.

6. Insulating coatings according to claim 5, characterized in that the insulating coatings have layer thicknesses of at least 0.3 mm.

7. Use of the insulating coatings according to claim 5 to 6 for thermal insulation, sound insulation or corrosion protection.