HK1070878B - Concrete moldings with a high gloss, their production and use - Google Patents

Description

High-gloss concrete molding, its production and use

Technical Field

The invention relates to a glossy and transparent coating for concrete moldings and to the use of such moldings as building materials.

Background

In the production of concrete mouldings, for example concrete roof tiles, the mortar mixture is first shaped and then (generally before curing or setting) coated with a coating or varnish to prevent lime whitening and to decorate. Thereafter the curing or setting of the concrete molding takes place together with the drying of the coating at elevated temperature: for roof tiles at a temperature range of 40 ℃ to 100 ℃. Since lime whitening can occur even when the cement is cured, it is important to use a coating as a frost-resistant protective weathering coating even for uncured concrete (known as fresh concrete). If desired, after curing or setting, a second or more coats of paint or varnish may be applied, each coat being dried.

Not only water-soluble but also solvent-based coating systems can be used. Water-soluble systems are now preferred for environmental reasons.

When roof tiles are coated with an aqueous coating system, which typically includes a water-soluble polymer dispersion binder, the properties of the coating system (e.g., stability, resistance to blooming, propensity to become fouled with algae, and dust pickup) can be purposefully influenced by appropriate selection of the polymer dispersion.

The use of (meth) acrylate and/or styrene based dispersions for the preparation of roof tile coatings has been found in DD-A124,808.

EP-A-492,210 describes the use of copolymers synthesized from specific monomers for reducing the tendency of concrete roof tiles to dust.

EP-A-383,002 discloses concrete roof tiles coated with ｃA coating based on an organotin copolymer dispersion and having ｃA low tendency to be contaminated by algae.

EP-A-894,780 describes the use of radiation-curable formulations for the coating of mineral mouldings, the purpose of which, among other things, is to increase the protection against blooming, with the disadvantages of technical complexity and increased costs.

EP-B-754,663 describes a process for producing a weathering coating for a cement-like substrate, in which a selected latex binder is used together with a foaming agent to coat the cement-like substrate, and the resulting bubbles are then broken up. The latices are prepared by emulsion polymerization using customary anionic, anionic or nonionic emulsifiers. Examples of anionic emulsifiers enumerated include alkali metal or ammonium alkyl sulfates, alkyl sulfonic acids, alkyl phosphonic acids, fatty acids, ethoxylated alkyl phenol sulfates and phosphates.

EP-A-469-295 describes concrete blocks coated with selected copolymers based on sulfonated diaryl ether emulsifiers for the purpose of reducing lime whitening.

WO-A-99/48841 describes the preparation of roof tile coating dispersions having sufficient stability and effective protection against blooming using carboxymethylcellulose as protective colloid. The dispersions are prepared by emulsion polymerization using conventional nonionic or ionic emulsifiers. Anionic emulsifiers which may be mentioned include the alkali metal or ammonium salts of alkyl, aryl or aralkyl sulphonic or phosphonic acids and also the alkyl, aryl sulphates or phosphates or compounds having other anionic end groups.

DE-C-10018469 discloses how the anti-blooming properties of dispersions as roof tile coatings can be improved by adding aqueous styrene-maleic anhydride copolymer solutions to the dispersions. The dispersion is prepared by using a common nonionic or ionic emulsifier by an emulsion polymerization method. Anionic emulsifiers which may be mentioned include the alkali metal or ammonium salts of alkyl, aryl or aralkyl sulphonic or phosphonic acids and also the alkyl, aryl or aryl sulphates and phosphates or compounds having other anionic end groups.

The dyeing of concrete mouldings, in particular of concrete roof tiles, makes it possible to use cement-binding inorganic coating compositions (known as cement slurries). The composition consists essentially of cement, water, pigment and, if desired, very fine sand. The coating composition is coated with a clear varnish immediately after it has been applied to the concrete molding and before it has cured or set. In this case, the task of the varnish is to prevent lime whitening and to increase the stability to weathering, the transparent varnish used in this process greatly influencing the gloss of the cured concrete moldings.

DE-C-3932573 describes a second cementitious inorganic layer applied by means of a concrete mass and by means of a roller coating or extrusion process. In this context, the coating materials used comprise known surface coatings composed of polymer dispersions and pigments and also additives.

GB-A-2030890 describes another concrete moulding consisting of a concrete body, a second cementitious inorganic layer and a coating applied thereto. The coating described in the examples contained quartz as a filler.

DE-A-19812142 discloses the possibility of using phosphate-containing emulsifiers in the preparation of dispersions as binders for roof tile coatings. However, it is not disclosed that these dispersions are also suitable for the preparation of clear varnishes. Wherein the dispersion contains a cellulose ether derivative as protective colloid. Such dispersions are assumed to have a broad particle size distribution and so the skilled person will prefer not to use them as a component in formulating clear coats.

Disclosure of Invention

Roof tile coatings or clear varnishes based on aqueous polymer dispersions, which are conventionally used for coating concrete mouldings, do provide adequate anti-blooming properties and a tendency to prevent dust pick-up, but for colour coatings, cement-bonded inorganic coating compositions give only a dull, very matt surface after the varnish has cured and dried.

It is therefore an object of the present invention to provide a coated concrete molding which is characterized by effective frost prevention and has improved gloss.

A second object of the present invention is to provide a simple and economical process for producing colored concrete moldings with high gloss and low tendency to efflorescence.

We have surprisingly found that cement mortar coated concrete mouldings can be coloured by applying selected coatings and that this gives the cured concrete moulding a glossy surface.

The invention provides concrete mouldings which have been coated with a coating comprising a cement-binding inorganic coating composition (cement mortar) and a transparent varnish comprising as binder an aqueous polymer dispersion, at least one anionic emulsifier containing at least one phosphate and/or phosphonate group.

The present invention also provides a method of producing a lustrous concrete moulding (such as a concrete roof tile) as described above, the method comprising:

a) the cement-binding inorganic molding compound which has not yet set is used to produce moldings.

b) Coating at least one surface of the moulding produced in step a) with coloured or colourless cement

-binding an inorganic coating composition (cement mortar),

c) coating the surface of the as yet unset cement-binding inorganic moulding mixture which has been coated with a cement paste with a transparent water-soluble varnish comprising an aqueous polymer dispersion binder in which an anionic emulsifier containing at least one phosphate and/or phosphonate group is used as a stabilizer, and

d) the mouldings and the cement mortar and the clear varnish are cured in a conventional manner.

The glossy concrete moldings of the invention also have good lime whitening resistance and good weathering stability.

The term "concrete moulding" includes concrete forming constructions, including concrete exposed to air, such as plates, pipes, especially roof tiles, etc. The concrete mouldings can be produced in conventional manner from mixed concrete, for example by extrusion techniques. As a result, its final shape is reached even at this stage.

The cement slurries are usually manufactured in ｃA stirred vessel from cement, sand, water, if appropriate with the addition of pigments and other additives, such as plasticizers or dispersants, etc. (see EP-A-1,114,806.) the cement slurries can be applied in ｃA conventional manner. Generally, the cement slurry is applied to the concrete molding before it is cured.

The aqueous varnish can also be applied directly after the cement slurry has been applied, by conventional techniques, before the cement slurry-coated concrete moulding has cured. Preferably by spraying.

The aqueous varnish used in the present invention is an aqueous clear varnish. Such paints are preferably pigment-free and/or filler-free coating materials. It is also possible to contain a small amount of pigment and/or filler, provided that the transparency of the varnish is not reduced. It is also possible to use transparent fillers.

The concrete molding thus obtained is subsequently cured. Typical curing temperatures are between 20 ℃ and 100 ℃, preferably 40 to 80 ℃. At this temperature, not only the concrete molding but also the cement mortar coating are cured and, in addition, the transparent varnish layer is dried.

The minimum film-forming temperature of the dispersions used in the invention for producing coated concrete mouldings is generally between 0 and 80 ℃, preferably between 0 and 50 ℃ and in particular between 0 and 30 ℃, the dispersions being produced by emulsion polymerization using anionic emulsifiers containing phosphate or phosphonate groups. It is also possible to add the emulsifier again after the polymerization has been completed.

The phosphate-functionalized emulsifiers used are preferably esters of phosphoric acid with alcohols and phenols (it is also possible to use mixtures of monoesters, diesters, triesters of phosphoric acid), esters of adducts of alcohols and/or (alkyl) phenols with ethylene oxide and/or propylene oxide with phosphoric acid, and the sodium, potassium and ammonium salts of these compounds. These compounds are commercially available, for example under the trademarks ® Berol 522 (potassium alkyl phosphate), ® Hostaphat 1306 (alkyl oligomeric ethoxylated phosphate) and ® Berol 733 (potassium alkylphenol oligomeric ethoxylated phosphate).

As the phosphate/ester functional group-containing emulsifier, a hydrocarbon as a copolymerizable emulsifier and an ethylenically unsaturated ester of phosphoric acid and a product obtained by neutralizing the same with a base can also be used. Mixtures of the above emulsifiers may also be used, as will be appreciated later.

As anionic emulsifiers containing phosphates and/or phosphonates, especially suitable are copolymerisable modified alcohol ether phosphates, for example Maxemul^®6106. 6112 and 6120 (from Unichema), straight chain C₈-C₁₂Alkali metal or ammonium salts of alkylphosphates (Hostaphat OPS, Clariant), straight-chain or branched C₁₀-C₁₈Alkali metal or ammonium salts of alkyl glycol ether phosphoric acid (Hostaphat K, produced by Clariant), alkylaryl polyglycol ether phosphate (Berol 733) and straight-chain or branched C₁₀-C₁₈Mono-or diesters of alkyl phosphoric acids (Hostaphat C, Berol 521 and 522) and mixtures of all of the above emulsifiers.

The last-mentioned group of emulsifiers is preferably used according to the invention.

Likewise, phosphoric monoesters are preferably used.

As anionic emulsifier, the aqueous polymer dispersion should contain from 0.2 to 5% by weight, preferably from 0.4 to 3% by weight, more preferably from 0.5 to 2% by weight, of the phosphorus compound according to the invention (based on the amount of polymer in the dispersion).

The dispersion may further comprise other nonionic or additional anionic emulsifiers.

As nonionic emulsifiers, use may be made, for example, of alcohol polyglycol ethers (such as lauryl alcohol, oleyl alcohol, stearyl alcohol or ethoxylated products such as mixtures of coconut oil fatty alcohols); alkylphenol polyglycol ethers (such as the ethoxylation products of octylphenol, nonylphenol, diisopropylphenol, triisopropylphenol or di-or tert-butylphenol); or ethoxylation products of polyoxypropylene.

Anionic emulsifiers which may also be used include alkali metal or ammonium salts of alkyl-, aryl-, or alkylaryl sulfonic acids and alkali metal or ammonium salts of alkylaryl, or alkylaryl sulfates, where also low polyethylene oxide units or polyethylene oxide units may be present between the hydrocarbon radical and the anion. Typical examples are sodium lauryl sulfate, undecyl glycol ether sulfate, sodium lauryl diglycol sulfate, sodium tetradecyl triethylene glycol sulfate, sodium octylphenol glycol ether sulfate, sodium dodecylbenzene sulfonate, sodium lauryl diglycol sulfate and ammonium tributylphenol pentaglycol or octaglycol sulfate. It is also possible to use the sulfonated diaryl ethers of formulｃA1 of EP-A-469,295.

Preferably, a mixture of anionic emulsifiers is used, at least one emulsifier containing phosphate and/or phosphonate groups being used in combination with another emulsifier containing sulfate or sulfonate groups.

Particularly preferred are mixtures of emulsifiers containing phosphate and/or phosphonate groups in an amount of at least 10% by weight, based on the total amount of emulsifiers used.

In order to stabilize the aqueous polymer dispersions used according to the invention, protective colloids can be used, provided that this does not significantly increase the particle diameter of the polymer dispersion. Average value of the mean particle diameter (D) of the Polymer dispersions used according to the invention₅₀Values) are generally in the range less than or equal to 200nm, preferably less than or equal to 150 nm.

Suitable protective colloids are copolymers based on polyvinylpyrrolidone, cellulose ether derivatives (cf. for example WO-A-99/48,841) and polyvinyl alcohols which are known and customary to the person skilled in the art.

The aqueous polymer dispersions used for producing the concrete moldings of the invention can be obtained by emulsion polymerization of free-radically polymerizable ethylenically unsaturated monomers, preferably using mixtures of such monomers.

Mixtures of preferred monomers containing acrylates and/or methacrylates and/or vinylaromatic compounds as main monomers, which consist of:

i)85 to 99.8% by weight of C₁To C₁₂Acrylic acid esters of alkanols, C₁To C₁₂Methacrylic acid esters of alkanols and/or vinylaromatic monomers.

ii) from 0.2 to 5% by weight of stabilizing monomers, such as copolymerizable carboxylic acids, copolymerizable amides, copolymerizable phosphates and/or phosphonates, copolymerizable sulfates and/or copolymerizable sulfonic acids and salts thereof, and

iii)0 to 10% by weight of further monomers.

Monomers i) used include C₁To C₁₂Acrylic and methacrylic esters of monoalcohols such as ethyl acrylate, butyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate and/or vinyl aromatic monomers such as styrene, vinyl toluene and the like.

Preference is given to using combinations of softening monomers (such as butyl acrylate and 2-ethylhexyl acrylate) and hardening monomers (such as methacrylates, cyclohexyl acrylate and styrene) known to the person skilled in the art, so that the corresponding dispersions obtained have a minimum film-forming temperature (MFFT) in the range from 0 to 80 ℃, preferably from 0 to 50 ℃, particularly preferably from 0 to 30 ℃ and very particularly preferably from 0 to 20 ℃.

If multistage emulsion polymerization is used, the preferred combination of the hardening and softening monomers and the mass ratios of the individual polymerization stages preferably results in a minimum film-forming temperature of the dispersion in the range from 0 to 80 ℃, preferably in the range from 0 to 50 ℃ and an elongation at break (for 100um thick films) of the corresponding dispersion film of > 100%.

The stabilizing monomers ii) used include copolymerizable carboxylic acids and amides such as acrylic acid, methacrylic acid, itaconic acid, acrylamide and methacrylamide, and/or copolymerizable sulfates and/or sulfonates, such as sodium vinylsulfonate, sulfoalkyl (meth) acrylates such as sodium sulfopropylmethacrylate (═ SPM)^®Produced by Rasching), sulfoalkyl (meth) acrylamides such as sodium acrylamido-2-methylpropanesulfonate (═ AMPS)^®Produced by Lubrizol).

Also usable as stabilizing monomers ii are free-radically copolymerizable monomer-modified phosphates and phosphonates. For example, vinyl phosphates or modified alcohol ether phosphates in which the aforementioned phosphates and phosphonates have been made copolymerizable.

As further monomers iii) it is possible to use keto group-containing monomers, for example acetoacetoxy group-containing monomers, such as ethyl acetoacetate methacrylate, butyl acetoacetate methacrylate, methacrylamidogetone and vinyl acetoacetate and copolymerizable diacetone derivatives such as diacetone acrylamide and diacetone methacrylamide.

Further monomers iii) which may be used include hydroxyalkyl (meth) acrylates, glycidic (meth) acrylates, alkoxyvinylsilanes, (meth) acryloyloxysilanes, (meth) acryloyloxyalkyl phosphates and polymerizable ethylene urea derivatives, such as N (. beta. - (meth) acryloyloxyethyl) -N, N '-ethylene urea and N (. beta. -acrylamidoethyl) N, N' -ethylene urea.

To improve the soiling characteristics, polyfunctional, at least two hydrazide groups, such as adipic acid dihydrazide, oxalic acid dihydrazide, isophthalic acid dihydrazide, polyacrylic acid polyhydrazide, etc., may be added to the dispersion containing, as the other monomer iii, a ketone group-containing monomer.

It is preferred to use equimolar amounts of hydrazide and ketone groups.

The polymerization of the aqueous polymer dispersions used in the process of the present invention can be carried out by conventional emulsion polymerization processes. Wherein the monomers are emulsified in the aqueous phase in the presence of emulsifiers, initiators and/or protective colloids and polymerized at temperatures typically from 50 to 95 ℃.

Emulsion polymerization can be accomplished by methods known to those skilled in the art (e.g., by batch, monomer metering, or emulsion feed methods).

Preference is given to the emulsion feed process in which a small amount of the monomers is prepolymerized and the remainder is metered in essentially in the form of an aqueous emulsion.

If desired, it is also possible to meter in two or more monomer emulsions in succession.

To initiate and continue the polymerization, oil-soluble and/or preferably water-soluble free-radical initiators or redox systems are used. Suitable examples include hydrogen peroxide, sodium peroxodisulfate, potassium, ammonium salts, dibenzoyl peroxide, lauryl peroxide, tert-butyl hydroperoxide, bisazo-diisobutyronitrile, used alone or in combination with reducing compounds such as sodium bisulfite, hydroxymethanesulfinate, glucose, ascorbic acid and other reducing compounds.

Preference is given to using peroxodisulfates.

In addition, regulators such as mercaptans, in particular n-dodecylmercaptan, thiophenol and 2-methyl-5-tert-butylbenzenethiol, may be used.

In general, amounts of from 0 to 1% by weight, preferably from 0 to 0.5% by weight, and it is particularly preferred not to use regulators for the preparation of the dispersions.

The water-soluble polymer dispersion is usually brought to a pH of from 6.5 to 10, preferably from 7.0 to 9.0, in a solution of ammonia, alkali metal hydroxide and alkaline earth metal. Buffers such as sodium hydrogen phosphate, sodium acetate and sodium hydrogen carbonate may also be used, if appropriate added during the emulsion polymerization.

For the production of the concrete moldings according to the invention, the water-soluble polymer dispersion complexes used as transparent varnishes preferably comprise further additives and components, such as are customary for the formulation of aqueous dispersion coating materials. As additives and further components, film-forming auxiliaries, e.g. white spirit, Texanol^®、TxiB^®Butyl glycol, butyl diglycol, butyl dipropylene glycol, butyl tripropylene glycol; plasticizers, e.g. dimethyl phthalate, diisobutyl adipate, Coasol B^®And Plastilit 3060^®(ii) a Wetting agents, e.g. AMP 90^®、TegoWet.280^®、Fluowet PE^®(ii) a Thickeners based on acrylates and polyurethanes, e.g. Borchigel L75^®And Tafigel PUR60^®(ii) a Anti-aging agents, antifoaming agents, such as mineral oil antifoaming agents and silicone oil antifoaming agents; UV protectors, e.g. Tinuvin 1130^®Dispersing agents, e.g. polyacrylic acids (e.g. Lopon 890)^®) Or styrene-maleic anhydride copolymers (as described, for example, in DE-C-10018469) or other additives and auxiliaries such as those customarily used in the formulation of coating compositions.

The concrete molding of the invention can be used as a building material, in particular in the form of panels or pipes, for use preferably in the form of roof tiles.

The invention also provides their use.

The following examples illustrate the invention, but the invention is not limited thereto.

Examples

A) Preparation of the Water-soluble Polymer Dispersion of the invention

Example 1:

emulsifier solution 1: concentration ofIs 28% by weight of C₁₀An aqueous solution of a potassium salt of an alkylphosphoric acid.

475g of deionized water and 25g of emulsifier solution 1 were added to the polymerization vessel and the initial charge was heated to 80 ℃ with stirring.

In the feed vessel, a monomer emulsion (feed stream 2) was prepared with stirring from the following components:

quantity component

645.00g deionized water

2.89g of sodium hydroxide

15.00g 2-acrylamido-2-methyl-propanesulfonic acid

2.50g ammonium persulfate

17.86g of emulsifier solution 1

500.00g of methyl methacrylate

500.00g of butyl acrylate

In a further feed vessel, an aqueous initiator solution (feed stream 2) was prepared from the following components

Quantity component

13.33g deionized water

0.50g ammonium persulfate

The feed stream heated at 80 ℃ initially charged in the polymerization reactor was in turn mixed in each case once with 60.00g of feed stream 1 and the entire feed stream 2, and the mixture was polymerized for 15 minutes at 80 ℃. The remaining feed stream 1 is then metered continuously into the reactor at a constant temperature of 80 ℃ over a period of 180 minutes. Finally, the polymerization was continued in the reactor at 80 ℃ for 60 minutes and then cooled to 25 ℃.

The solid content of the polymer dispersion was 47.0%

Example 2:

emulsifier solution 1: c at a concentration of 28% by weight₁₀An aqueous solution of a potassium alkyl phosphate salt.

Emulsifier solution 2: ethoxylated C with an average degree of ethoxylation of about 7 at a concentration of 28% by weight₁₁Aqueous sodium monoester sulfate salt solution of alcohol.

The polymerization reactor was charged with 475g of deionized water and 16.43g of emulsifier solution 1 and 8.21g of emulsifier solution 2, and the initial charge was heated to 80 ℃ with stirring.

In the addition vessel, a monomer emulsion (feed stream 1) was prepared with stirring from the following components:

quantity component

644.00g deionized water

2.89g of sodium hydroxide

15.00g 2-acrylamido-2-methyl-propanesulfonic acid

2.50g ammonium persulfate

14.29g of emulsifier solution 1

7.14g of emulsifier solution 2

500.00g of methyl methacrylate

500.00g of butyl acrylate

In a further feed vessel, an aqueous initiator solution was prepared from the following components:

quantity component

13.33g deionized water

0.50g ammonium persulfate

The reaction was carried out as in example 1.

The resulting aqueous polymer dispersion had a solids content of 47.0%

Example 3:

emulsifier solution 1 and emulsifier solution 2: the same as in example 2.

The polymerization reactor was charged with 475g of deionized water and 12.50g of emulsifier solution 1 and 12.50g of emulsifier solution 2, and the initial charge was heated to 80 ℃ with stirring.

In a further feeder, a monomer emulsion (feed stream 1) was prepared with stirring from the following components:

quantity component

643.00g deionized water

2.89g of sodium hydroxide

15.00g 2-acrylamido-2-methyl-propanesulfonic acid

2.50g ammonium persulfate

8.93g of emulsifier solution 1

12.50g of emulsifier solution 2

500.00g of methyl methacrylate

500.00g of butyl acrylate

In a further feed vessel, an initiator solution (feed stream 2) was prepared from the following components:

quantity component

13.33g deionized water

0.50g ammonium persulfate

The reaction was carried out in the same manner as in example 1.

The solid content of the aqueous polymer dispersion was 47%

Example 4:

emulsifier solution 1 and emulsifier solution 2: the same as in example 2.

The polymerization reactor was charged with 475g of deionized water and 8.21g of emulsifier solution 1 and 16.43g of emulsifier solution 2, and the initial charge was then heated to 80 ℃ with stirring.

In a feeder, a monomer emulsion (feed stream 1) was prepared with stirring from the following components:

quantity component

644.00g deionized water

2.89g of sodium hydroxide

15.00g 2-acrylamido-2-methyl-propanesulfonic acid

2.50g ammonium persulfate

7.14g of emulsifier solution 1

14.29g of emulsifier solution 2

500.00g of methyl methacrylate

500.00g of butyl acrylate

In a further feed vessel, an aqueous initiator solution (feed stream 2) was prepared from the following components:

quantity component

13.33g deionized water

0.50g ammonium persulfate

The reaction was carried out in the same manner as in example 1.

The resulting aqueous polymer dispersion had a solids content of 47.0%.

B) Preparation of aqueous comparative dispersions

Emulsifier solution 2: b at a concentration of 28% by weightOxy radical C₁₁Sulfuric acid monoester sodium salt of alcohol (with an average degree of ethoxylation of about 7).

A polymerization reactor was charged with 475g of deionized water and 25g of emulsifier solution 2 emulsifier solution and heated to 80 ℃ with stirring

In a feed vessel, a monomer emulsion (feed stream 1) was prepared with stirring from the following components:

quantity component

645.00g deionized water

2.89g of sodium hydroxide

15.00g 2-acrylamido-2-methyl-propanesulfonic acid

2.50g ammonium persulfate

17.86g emulsifier solution 2

500.00g of methyl methacrylate

500.00g of butyl acrylate

In a further feed vessel, an aqueous initiator solution (feed stream 2) was prepared from the following components

Quantity component

13.33g deionized water

0.50g ammonium persulfate

The feed stream heated at 80 ℃ initially charged in the polymerization reactor was in turn mixed in each case once with 60.00g of feed stream 1 and the entire feed stream 2, and the mixture was polymerized for 15 minutes at 80 ℃. The remaining feed stream 1 is then metered continuously into the reactor at a constant temperature of 80 ℃ over a period of 180 minutes. Finally, the polymerization was continued in the reactor at 80 ℃ for 60 minutes and then cooled to 25 ℃.

The resulting aqueous polymer dispersion had a solids content of 47.0%.

C) Preparation of clear varnish

The aqueous polymer dispersions of examples 1 to 5 were modified with additives and film-forming auxiliaries as follows before being used as clear varnishes.

100pbw (parts by weight) of the dispersions of examples 1-5 were mixed with a mixture consisting of 3.5pbw of butyldiglycol and 2pbw of water with stirring.

Next, 0.1pbw of a silicon defoamer, Tego Foamex825, was stirred into the resulting mixture. The clear varnish K is obtained by this procedure₁To K₅See table below.

Transparent varnish	The dispersions used
		K1	Example 1
K2	Example 2
		K3	Example 3
K4	Example 4
		Comparative transparent varnish K5	Comparative example 5

D) Preparation of test samples

Clear varnish K such as C₁To K₅The coating is applied to the colored cement slurry as follows.

Quantity component

25pbw of water

30pbw of quartz sand F35^®(Quarzwerk Frechen, maximum particle size 0.355mm)

50pbw of cement CEM142.5

1pbw Bayferro 960^®

To prepare the colored cement slurries, water was added and then the solids and the already premixed components were mixed in with a concrete mixer over a period of 5 minutes. The slurry thus obtained was then spread on a prewetted Eterplan board, in each case 1mm in film thickness and 20X 20cm in area²Immediately thereafter, the clear varnish K described in C was applied by spraying onto the thus-coated sample₁To K₅Coated on a wet, uncured sample (25 g/m)²) Coated with 3g of each of the clear varnishes and then dried in an oven at 40 ℃ and 95% humidity for 16 hours.

E) Measurement of gloss

The degree of surface gloss of the samples obtained according to D) was determined, giving the following measurements as a function of the clear varnish used:

water-soluble clear varnishes such as C used	Gloss determination (determination angle 60 degree)
		K1	6.1
K2	1.7
		K3	1.6
K4	1.2
		Comparative transparent varnish K5	0.6

Claims (18)

1. Concrete moulding with a cement-binding inorganic coating composition and a transparent varnish, the transparent varnish containing, as binder, an aqueous polymer dispersion containing at least one anionic emulsifier containing at least one phosphate or phosphonate group, and wherein the aqueous polymer dispersion contains a polymer emulsion derived from a monomer mixture having the following composition:

i)85 to 99.8% by weight of esters of C1 to C12 alkanols with acrylic acid, esters of C1 to C12 alkanols with methacrylic acid and/or vinylaromatic monomers,

ii) from 0.2 to 5% by weight of a copolymerizable carboxylic acid, a copolymerizable amide, a copolymerizable phosphate or phosphonate, a copolymerizable sulfate and/or sulfonic acid and salts thereof, and

iii)0 to 10% by weight of further monomers.

2. The concrete molding of claim 1 wherein the anionic emulsifier is selected from the group consisting of esters of phosphoric acid with alcohols and phenols, esters of phosphoric acid with adducts of alcohols and/or phenols and/or alkylphenols and ethylene oxide and/or propylene oxide, the sodium, potassium, ammonium salts of these compounds, and mixtures of the aforementioned emulsifiers.

3. The concrete molding of claim 2 wherein the ester of phosphoric acid with an alcohol and a phenol is a mixture of mono-, di-, and tri-esters of phosphoric acid.

4. The concrete molding of claim 2 wherein the anionic emulsifier is selected from the group consisting of ethylenically unsaturated esters of phosphoric acid with hydrocarbons and neutralization products derived therefrom with bases.

5. The concrete molding of any of claims 2 to 4, wherein the anionic emulsifier is selected from the group consisting of modified alcohol ether phosphates, linear C, copolymerizable with phosphate and/or phosphonate groups₈-C₁₂Alkali metal or ammonium salts of alkylphosphonic acids, straight-chain or branched C₁₀-C₁₈Alkali metal or ammonium salts of alkylpolyglycol ether phosphates, alkylaryl polyglycol ether phosphates, and linear or branched C₁₀-C₁₈Alkali metal or ammonium salts of alkylphosphoric acid monoesters and diesters, and mixtures of the aforementioned emulsifiers.

6. The concrete molding of claim 1, wherein in addition to the anionic emulsifier containing at least one phosphate and/or phosphonate group, there is combined therewith at least one anionic emulsifier containing at least one sulfate or sulfonate group.

7. The concrete molding of claim 1 wherein monomer i) is C₁To C₁₂Acrylic and methacrylic esters of monoalcohols and/or vinylaromatic monomers.

8. The concrete molding of claim 7 wherein the monomer i) is a combination of butyl acrylate and 2-ethylhexyl acrylate with methyl methacrylate, cyclohexyl methacrylate and styrene.

9. The concrete molding of claim 1 wherein the monomer ii) is selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, acrylamide, methacrylamide, sodium vinyl sulfonate, sulfoalkyl (meth) acrylates, sulfoalkyl acrylamides, sulfoalkyl (meth) acrylamides, and mixtures thereof.

10. The concrete molding of claim 1 wherein the monomer iii) is a ketone group-containing monomer.

11. The concrete molding of claim 10 wherein the monomer iii) is a copolymerizable derivative of an acetoacetoxy-containing monomer and diacetone.

12. The concrete molding of claim 11, wherein the monomer iii) is ethyl acetoacetate methacrylate, butyl acetoacetate methacrylate, acrylamidomethylacetoacetone or vinyl acetoacetate or a copolymerizable derivative of diacetone acrylamide.

13. The concrete molding of claim 1 wherein the monomer iii) is selected from the group consisting of hydroxyalkyl acrylates, hydroxyalkyl methacrylates, glycidyl acrylates, glycidyl methacrylates, alkoxy vinyl silanes, acryloxy silanes, methacryloxy silanes, acryloxy alkyl phosphates, methacryloxy alkyl phosphates and polymerizable ethylene urea derivatives and combinations thereof.

14. The concrete molding of any of claims 10 to 12, wherein the ketone group-containing monomer is mixed with a polyfunctional carboxyhydrazide containing at least two hydrazide groups.

15. A method of producing the concrete molding of claim 1, the method comprising:

a) a moulding is produced from the cement-bonded inorganic moulding mixture which has not yet solidified,

b) applying a coloured cement-binding inorganic coating composition on at least one surface of the moulding obtained in step a),

c) coating the surface of a cement-cement slurry coating of a mixture of cement inorganic mouldings which have not set with a transparent varnish comprising a binder of an aqueous polymer dispersion stabilized with an anionic emulsifier containing at least one phosphate and/or phosphonate group,

d) the mouldings and the coating of cement mortar and clear varnish are cured in a conventional manner.

16. The method of claim 15, wherein the aqueous polymer dispersion is emulsion polymerized with at least one phosphate and/or phosphonate ester anionic emulsifier and has a minimum film forming temperature of between 0 ℃ and 80 ℃.

17. Use of the concrete molding according to claim 1 as a building material.

18. Use of the concrete molding of claim 17 in the form of a plate, a pipe or a roof tile.