RU2588130C2 - Multistage polymer dispersions, method for preparation and use thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to aqueous multi-step polymer dispersions obtained by radically initiated aqueous emulsion polymerisation. Provided an aqueous dispersion of multi-stage polymerisates containing a soft and solid phase, with ratio of soft phase to hard phase of 25-95 wt% to 75-5 wt%, glass transition temperature (T_g) of soft phase obtained in first stage is -30-0 °C, while T_g of hard phase obtained in the second step is 20-60 °C, and wherein dispersion containing units of at least one monomer of general formula (I), where n is a number from 0 to 2, R1, R2, R3 each independently represent hydrogen or methyl group, X is oxygen or NH and Y is hydrogen, an alkali metal or NH₄. Also provided are versions of application of dispersion, as well as mineral moulded articles and fibre-cement boards coated with said dispersion.

EFFECT: technical result is disclosed dispersion enables to obtain coatings with high weather resistance, resistance to adhesion and fading.

13 cl, 1 tbl, 5 ex

Description

The invention relates to aqueous multi-stage polymer dispersions obtained by radically initiated aqueous emulsion polymerization, which contain a soft and a solid phase, and the ratio of solid phase to soft phase is 25-95% of the mass. to 75-5% wt., and the glass transition temperature (T _g ) obtained in the first stage of the soft phase is from -30 to 0 ° C, while T _g obtained in the second stage of the solid phase is from 20 to 60 ° C and wherein the dispersions comprise units of at least one monomer of the general formula (I):

wherein

n means a number from 0 to 2,

R1, R2, R3 independently from each other mean hydrogen or methyl group,

X is oxygen or NH,

Y is hydrogen, alkali metal or NH ₄ .

In addition, the invention relates to a method for producing said aqueous dispersions of polymers, their use as binders in coatings, and also to coatings containing the polymer dispersion according to the invention.

Aqueous dispersions of polymers of the prior art are used as binders in coating agents intended, in particular, to provide coatings for mineral surfaces and mineral molded products, such as, for example, fiber cement boards and side wall claddings. Fiber cement boards and side wall claddings are high-quality building materials that offer numerous advantages over other building materials, such as wood cladding, PVC panels, or metal cladding, such as aluminum or sheet steel. The main advantage of fiber cement boards is their durability under atmospheric conditions, as well as high mechanical stability, which often exceeds the stability of other building materials. Fiber-cement boards are made of cement, water, optionally used fillers, such as sand or silicon dioxide, and fibrous components based on natural, for example, wood or cellulose fibers, as well as synthetic fibers. The appropriate mixture is placed in a mold, dehydrated on a strainer if necessary, and then cured. The wet mass can be cured as such or compressed by compression so that a higher final strength can be achieved after curing. Fiber cement boards can be made in the form of flat products, as well as in the form of so-called wavy sheets. Fiber cement boards or cladding of side walls by embossing can be provided with a surface structure, giving them an appearance that resembles, for example, the surface of wood. Sheets can be cut to produce products of different shapes and sizes: large panels, small squares, rectangles, rhombuses or products similar to slate or other building materials. The thickness of the resulting fiber cement boards is usually from 3 to 20 mm.

Fiber cement boards and side wall cladding are subject to curing. Curing is most often carried out in humidified heat chambers under pressure or without pressure. At temperatures in the range from more than 30 ° C to about 70 ° C, the curing of cement is accelerated and completed within a few hours, which allows to obtain a material with sufficient strength against destruction. Curing can also be carried out in an autoclave under pressure, which also allows to achieve much higher temperatures, since this can ensure the absence of volatilization of water and the "burning" of cement. In this case, the water required for cement hydration does not evaporate. Autoclaving is carried out, for example, in an approximate temperature range from 100 to 180 ° C.

The disadvantage of mineral surfaces and mineral molded products, such as fiber cement boards, is the erosion of cationic components, such as Ca ²⁺ , that occurs over time under atmospheric conditions (especially under the influence of water), which leads to a decrease in the strength of the plates. Another disadvantage of mineral surfaces is fading. This phenomenon is supposedly to be explained by the fact that mineral binders contain polyvalent cations, such as Ca ^2+, surrounded by an alkaline external environment. As a result of interaction with carbon dioxide in the air on the surface of mineral molded products, white lime spots that are hardly soluble in water can form, giving the product a very unattractive appearance. Fading can occur both in the process of solidification of freshly made mineral molded products, and in atmospheric conditions on the surface of already solidified mineral molded products.

In order to eliminate the above disadvantages, mineral molded products are often provided with a coating. To do this, currently usually use aqueous coating systems, which as a film-forming component contain an aqueous polymer dispersion. The binders commonly used for this are styrene-acrylic ester copolymers, vinyl acetate homopolymers and copolymers, pure acrylates and similar polymers (see, for example, German patent DE 2164256). However, coatings obtained using such binders are not able to satisfactorily prevent the cationic components from passing through them (fading). In addition, such coatings are easily susceptible to contamination.

Lime fading already occurs when cement sets, and it may be appropriate to coat as a protection against fading on uncured concrete or cement (the so-called "green concrete"). After curing, respectively setting, if necessary, you can carry out additional application of the second or subsequent coating in the form of paint or colorless varnish and the corresponding subsequent drying. In other cases, protection against fading is applied to the substrate only upon completion of curing.

The protection of mineral surfaces and molded products from the above-mentioned fading can also be enhanced by coating compositions based on styrene / acrylate dispersions, respectively pure acrylate dispersions, as described in European patent application EP-A 469295 and German patent application DE-A 19514266 In European patent application EP-A 469295, it is recommended to use a special anionic emulsifier for this purpose, and in German patent application DE-A 19514266 polymers containing units of specific monomers with sulfonate groups.

German patent DE 10343726 describes coated concrete molded products with high fading protection achieved through the use of aqueous polymer dispersions and an anionic emulsifier containing at least one phosphate and / or phosphonate group.

European patent EP 915071 proposes coatings based on copolymers of ethylenically unsaturated monomers containing from 0.2 to 5% by weight. itaconic acid.

A method for preserving concrete roof tiles using an aqueous polymer dispersion containing P polymerizate, which preferably contains 2-acrylamido-2-methylpropanesulfonic acid units in a radically polymerized form, is proposed in European patent EP 821660.

In European patent EP 623659 published multistage polymer dispersions and their use in coating agents. However, in these dispersions there are no monomer units of the general formula (I).

In European patent EP 1466929 described are multi-stage latex polymers and their use in coating compositions, respectively, as a “protective layer”, intended, in particular, for fiber cement.

International application WO 03/031526 describes multistage latex polymers with a glass transition temperature gradient (T _g ) and their use.

European patent EP 894780 describes coating compositions for mineral molded products, for example, fiber cement boards, containing polymer P2, which is a multi-stage polymer.

European patent EP 1948574 describes a fiber cement product coated with an impact-resistant multi-stage latex polymer as a coating composition. The multistage latex polymer has a T _g gradient.

None of the multistage polymers published in the prior art contains monomer units of the general formula (I).

To provide the necessary protection against fading, fiber cement boards after their manufacture and curing are often coated with an aqueous dispersion or paint based on an aqueous acrylate binder. The coating can be applied by dipping, spraying, rolling with rollers, a brush or by means of a so-called lacquer device. Sometimes the reverse side and the edges of the fiber cement board are also covered. After coating and drying, still warm fiber cement boards are most often stacked. In this case, mutual adhesion of the coated plates can occur, since the binder of the coating has too high softness and, at the same time, lack of resistance to adhesion.

The disadvantage of one-step binders in the coatings of the prior art is that they often have too high rigidity to provide optimal adhesion resistance, and therefore the corresponding composition cannot be obtained without the use of a solvent or film-forming component. In addition, the protection of such coatings from fading often requires improvement. Under atmospheric conditions in the open air, such coatings can easily crack and become dull, that is, they do not have sufficient weather resistance.

The two-stage binders of the prior art due to the presence of a solid phase in them have satisfactory adhesion resistance, however, their weather resistance does not meet the requirements for it.

Thus, the present invention was based on the task of proposing a binder, as well as coating agents, primarily for mineral molded products, such as fiber cement coatings, which are characterized by increased weather resistance, as well as excellent adhesion resistance and excellent fading protection.

It was unexpectedly found that from multi-stage polymer dispersions obtained by radically initiated aqueous emulsion polymerization, which contain a soft and a solid phase, and the ratio of solid phase to soft phase is 25-95% of the mass. to 75-5% of the mass. (in terms of the weight of the polymer), and the glass transition temperature (T _g ) obtained in the first stage of the soft phase is from -30 to 0 ° C, while T _g obtained in the second stage of the solid phase is from 20 to 60 ° C and wherein the dispersions comprise units of at least one monomer of the general formula (I):

wherein

n means a number from 0 to 2,

R1, R2, R3 independently from each other mean hydrogen or methyl group,

X is oxygen or NH,

Y is hydrogen, alkali metal, NH ₄ ,

it is possible to obtain coatings with high weather resistance and at the same time excellent protection against fading and low ability to stick together.

Suitable substrates are industrially coated cement substrates (e.g. fiber cement slabs) as well as inorganic / organic substrates such as facades. Increased weather resistance, which can be explained by extremely good film formation (low MFT) at the same time relatively high hardness of the film, is manifested, for example, in the increased gloss of colorless varnishes or low-pigment coatings after exposure to ultraviolet / water (for example, a sun / xenon test or external atmospheric impact), respectively, high color fastness of coatings with increased pigmentation. In addition to high weather resistance, the systems have excellent resistance to adhesion and excellent protection against fading.

Under the inventive aqueous multistage polymer dispersion is preferably meant an aqueous polymer dispersion, the soft phase of which, obtained in the first stage, has a T _g in the range from -30 to 0 ° C, preferably from -20 to 0 ° C, while obtained in the second stage, the solid phase has a T _g in the range from 20 to 60 ° C, preferably from 30 to 50 ° C, and the ratio of the solid phase to the soft phase is (25-95) :( 25-5).

In addition, the present invention relates to a method for producing an aqueous polymer dispersion according to the invention, its use as a binder for mineral and non-mineral substances, and also to its use in coating agents, primarily for coating mineral molded products, such as fiber cement coatings.

Another object of the present invention are coatings containing the inventive aqueous polymer dispersion, as well as mineral molded articles containing the inventive polymer dispersion as a coating.

Thanks to the addition of monomers (I), much higher quality coatings are obtained for mineral molded products, in particular fiber cement boards.

The polymer dispersions obtained according to the invention can be synthesized by radical emulsion polymerization of ethylenically unsaturated compounds (monomers). In the first stage, the polymer is obtained from monomers that contain at least one monomer (I), and also, if necessary, a monomer with at least one acid group, the amount of which is 0.1 mass parts, preferably from 0.5 to 2 5 parts by weight in terms of the total number of monomers used in the first and second stages.

The acid monomers used in the first stage are capable of copolymerizing with monomers that do not contain an acid group. Obtained in the first stage, the polymer is preferably formed from at least 40% of the mass. nonionic basic monomers, which are discussed in more detail below, as well as from monomers of a different type, selected from the group consisting of ethylenically unsaturated acidic monomers. In addition, the polymer obtained in the first step, if necessary, can be synthesized from other, preferably non-ionic monomers. Obtained in the first stage, the polymer preferably contains at least 40 wt. -%, especially from 60 to 99% of the mass. or from 80 to 98% of the mass. (in terms of all the monomers of the first stage) of the units of the main monomers selected from the group consisting of alkyl (meth) acrylates with 1-20 carbon atoms, vinyl esters of carboxylic acids containing up to 20 carbon atoms, vinyl aromatic compounds with up to 20 carbon atoms , ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of alcohols with 1-10 carbon atoms, aliphatic hydrocarbons with 2-8 carbon atoms and one or two double bonds and mixtures of these monomers. The main monomers used to prepare the polymer in the first stage are, for example, alkyl esters of (meth) acrylic acid with 1-10 carbon atoms in the alkyl radical, such as methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate. Mixtures of alkyl esters of (meth) acrylic acid are also particularly suitable. Vinyl esters of carboxylic acids with 1-20 carbon atoms are, for example, vinyl laurate, vinyl stearate, vinyl propionate, vinyl ester of versatic acid and vinyl acetate. As vinyl aromatic compounds, vinyl toluene, alpha-methylstyrene, para-methylstyrene, alpha-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and preferably styrene can be used. Examples of suitable nitriles are acrylonitrile and methacrylonitrile. Vinyl halides are ethylenically unsaturated compounds substituted with chlorine, fluorine or bromine, preferably vinyl chloride and vinylidene chloride. Suitable vinyl ethers are, for example, vinyl methyl ether or vinyl isobutyl ether. Preferred are vinyl ethers of alcohols with 1-4 carbon atoms. Suitable hydrocarbons with 4-8 carbon atoms and two olefinic double bonds are butadiene, isoprene and chloroprene. Preferred basic monomers for producing the first-stage polymer are alkyl acrylates with 1-10 carbon atoms, alkyl methacrylates with 1-10 carbon atoms, vinyl esters containing up to 20 carbon atoms of carboxylic acids, and mixtures of these monomers, in particular alkyl acrylates with 1-8 carbon atoms , alkyl methacrylates with 1-8 carbon atoms and vinyl esters. Even more preferred monomers are 2-ethylhexyl acrylate, butyl acrylate, methyl methacrylate and styrene.

In addition, the polymer of the first stage, if necessary, contains 0.1% of the mass., Primarily from 0.5 to 2.5% of the mass. ethylenically unsaturated acid monomers in terms of all monomers of the first stage. Ethylenically unsaturated acid monomers are, for example, ethylenically unsaturated carboxylic acids, ethylenically unsaturated sulfonic acids and vinylphosphonic acid. As ethylenically unsaturated carboxylic acids, alpha-mono-ethylenically unsaturated or beta-monoethylenically unsaturated monocarboxylic and dicarboxylic acids with 3-6 carbon atoms in a molecule are preferably used. Suitable examples are acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinylacetic acid, vinyl lactic acid, and 2-carboxyethyl acrylate. Suitable ethylenically unsaturated sulfonic acids are, for example, vinyl sulfonic acid or styrene sulfonic acid. Preferred are acrylic acid, methacrylic acid, or a mixture thereof.

Along with this, amides and hydroxyalkyl esters of α, β-unsaturated carboxylic acids with 3-6 carbon atoms can be used as first stage monomers, particularly preferably acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl (meth) acrylate or 1,4-butanediol monoacrylate. Monomers can be used individually or in combination, for example, with acids and amides.

In addition, monomers of the general formula (I) are used as monomers of the first stage.

Monomers of the type indicated above include, for example:

2-acrylamido-2-methyl-propanesulfonic acid, 3'-sulfopropyl ester of methacrylic acid, 3'-sulfopropyl ester of acrylic acid and 2'-sulfo-ethyl ester of methacrylic acid.

Suitable alkali metal salts with monomers of the general formula (I) are, in particular, sodium, ammonium and potassium salts.

In a preferred embodiment, the polymer of the first stage is a copolymer:

(i) which is used in an amount of from 5 to 50% of the mass. in terms of 100 mass.h. all subject to polymerization in the first and second stages of the monomers,

(ii) which is synthesized from at least 80% of the mass. and up to 99% of the mass. basic monomers selected from the group consisting of alkyl (meth) acrylates with 1-10 carbon atoms, amides and hydroxyalkyl esters of α, β-unsaturated carboxylic acids with 3-6 carbon atoms, particularly preferably acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2 -hydroxyethyl methacrylate, 2-hydroxy-propyl (meth) acrylate or 1,4-butanediol monoacrylate and mixtures of these monomers, in particular n-butyl acrylate, methyl methacrylate and acrylamide, and

(iii) which is synthesized from at least 0.1% of the mass. and up to 5% of the mass. monomers (I), preferably selected from the group consisting of 2-acrylamido-2-methylpropanesulfonic acid, 3'-sulfopropyl ester of methacrylic acid, 3'-sulfopropyl ester of acrylic acid and 2'-sulfo-ethyl ester of methacrylic acid.

In a preferred embodiment, the polymerization in the first stage is carried out in the presence of seed latex. The seed latex is an aqueous dispersion of finely divided polymer particles with an average diameter of preferably from 20 to 40 nm. The seed latex is used in an amount preferably from 0.05 to 5% by weight, particularly preferably from 0.1 to 3% by weight. in terms of the total number of monomers of the first and second stages. Suitable, for example, are polystyrene or polymethyl methacrylate-based latex. A preferred seed latex is polystyrene seed latex.

The monomers used for the polymerization in the second stage are preferably at least 60% by weight, preferably at least 80% by weight, for example, from 80 to 100% by weight, particularly preferably at least 95% by weight. one or more of the main monomers of the second stage described below (in terms of total amount). The main monomers are selected from the group consisting of alkyl (meth) acrylates with 1-2 carbon atoms, vinyl esters of carboxylic acids containing up to 20 carbon atoms, vinyl aromatic compounds containing up to 20 carbon atoms, ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of alcohols with 1-10 carbon atoms, aliphatic hydrocarbons with 2-8 carbon atoms and one silt with two double bonds and mixtures of these monomers.

Mention should be made, for example, of alkyl esters of (meth) acrylic acid with 1-10 carbon atoms in the alkyl radical, such as methyl methacrylate, methyl acrylate, n-butyl acrylate, n-butyl methacrylate, ethyl acrylate and 2-ethylhexyl acrylate. Suitable, in particular, are also mixtures of alkyl esters of (meth) acrylic acid. Vinyl esters of carboxylic acids with 1-20 carbon atoms are, for example, vinyl laurate, vinyl stearate, vinyl propionate, vinyl esters of versatic acid and vinyl acetate. As vinyl aromatic compounds, vinyl toluene, alpha-methylstyrene, para-methylstyrene, alpha-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and preferably styrene can be used. Examples of nitriles are acrylonitrile and methacrylonitrile. Vinyl halides are ethylenically unsaturated compounds substituted with chlorine, fluorine or bromine, preferably vinyl chloride and vinylidene chloride. As vinyl ethers, mention may be made, for example, of vinyl methyl ether or vinyl isobutyl ether. Vinyl ethers of alcohols containing from 1 to 4 carbon atoms are preferred. Hydrocarbons with 4-8 carbon atoms and two olefinic double bonds are butadiene, isoprene and chloroprene.

The main monomers for polymerization in the second stage are preferably alkyl acrylates with 1-10 carbon atoms and alkyl methacrylates with 1-10 carbon atoms, in particular alkyl acrylates with 1-8 carbon atoms and alkyl methacrylates with 1-10 carbon atoms, as well as vinyl aromatic compounds, in particular styrene, and mixtures thereof. Even more preferred are methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, n-hexyl acrylate, octyl acrylate, 2-ethyl hexyl acrylate, 2-propyl heptyl acrylate, styrene, vinyl acetate, as well as mixtures of these monomers.

In addition to the basic monomers, the monomers for the polymerization in the second stage may include other monomers, for example, monomers with carboxylic acid, sulfonic acid or phosphonic acid groups. Carboxylic acid groups are preferred. These include, for example, acrylic acid, methacrylic acid, itaconic acid, maleic acid or fumaric acid. Other monomers are, for example, also monomers containing hydroxyl groups, in particular hydroxyalkyl (meth) acrylates with 1-10 carbon atoms, as well as (meth) acrylamide. Further monomers include phenyloxyethyl glycolmono (meth) acrylate, glycidyl acrylate, glycidyl methacrylate and amino (meth) acrylates such as 2-aminoethyl (meth) acrylate. Other monomers also include crosslinking monomers.

In addition, the polymer of the second stage, if necessary, contains 0.1% of the mass., Primarily from 0.5 to 2.5% of the mass. (in terms of all the monomers of the second stage) ethylenically unsaturated acid monomers. Ethylenically unsaturated acid monomers are, for example, ethylenically unsaturated carboxylic acids, ethylenically unsaturated sulfonic acids and vinylphosphonic acid. As ethylenically unsaturated carboxylic acids, alpha-monoethylenically unsaturated or beta-monoethylenically unsaturated monocarboxylic and dicarboxylic acids with 3-6 carbon atoms in a molecule are preferably used. Examples thereof are acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinylacetic acid, vinyl lactic acid, and 2-carboxyethyl acrylate. Suitable ethylenically unsaturated sulfonic acids are, for example, vinyl sulfonic acid or styrene sulfonic acid. Preferred are acrylic acid, methacrylic acid, and mixtures thereof.

Along with this, amides and hydroxyalkyl esters of α, β-unsaturated carboxylic acids with 3-6 carbon atoms can be used as second-stage monomers, particularly preferably acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl (meth) acrylate or 1,4-butanediol monoacrylate. Monomers can be used individually or in combination, for example, with acids and amides.

Monomers of the general formula (I) are also used as monomers of the second stage.

These include, for example:

2-acrylamido-2-methylpropanesulfonic acid, 3'-sulfopropyl ester of methacrylic acid, 3'-sulfopropyl ester of acrylic acid and 2'-sulfo-ethyl ester of methacrylic acid.

Suitable alkali metal salts and monomers of the general formula (I) are, in particular, sodium, ammonium and potassium salts.

The monomers for polymerization in the second stage are, in particular, at least 60% by weight, particularly preferably at least 80% by weight, for example, from 60 to 99% by weight. and even more preferably at least 95% of the mass. monomers selected from the group comprising at least one alkyl acrylate with 1-20 carbon atoms, at least one alkyl methacrylate with 1-20 carbon atoms, a mixture thereof or a mixture thereof with at least one other monomer selected from the group consisting of amides and hydroxyalkyl esters of α, β-unsaturated carboxylic acids with 3-6 carbon atoms, particularly preferably acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl (meth) acrylate or 1,4-butane-diolmonoacrylate.

The monomers for polymerization in the first stage are selected so that the estimated glass transition temperature of the polymer obtained from one of the monomers of the first stage is from -30 to 0 ° C, while the estimated glass transition temperature of the polymer obtained from one of the monomers of the second stage is from 20 to 60 ° C.

The purposeful variation of the type and amount of monomers enables specialists to obtain, according to the invention, aqueous polymer compositions in which the polymers contained have a glass transition temperature in the required range. The corresponding orientation is possible using the Fox equation. According to Fox (TG Fox, Bull. Am. Phys. Soc. 1956 [series II] 1, p. 123 and according to Ullmann's Encyclopädie der technischen Chemie, Volume 19, p. 18, 4th edition, Chemie, Weingheim, 1980 ) to calculate the glass transition temperature of the copolymers in a good approximation, the ratio:

, $$T_g^2$$

, … $$T_g^n$$

означают температуры стеклования (в градусах Кельвина) полимеров, синтезированных соответственно только из одного из мономеров 1, 2, …n. Значения T_g гомополимеров большинства мономеров известны и приведены, например, в Ullmann's Ecyclopedia of Industrial Chemistry, том 5, том А21, с.169, издательство VCH, Вейнгейм, 1992; другими источниками температур стеклования гомополимеров являются, например, J. Brandrup, Е.Н. Immergut, Polymer Handbook, 1-е издание, издательство J. Wiley, Нью-Йорк 1966, 2- издание, издательство J. Wiley, Нью-Йорк 1975, и 3-е издание, издательство J. Wiley, Нью-Йорк 1989. Для этилакрилата используют значение T_g -13°С.in which x ¹ , x ² , ... x ⁿ mean the mass fraction of monomers 1, 2, ... n and $$T_g^{\mathrm{one}}$$

, $$T_g^2$$

, ... $$T_g^n$$

mean glass transition temperatures (in degrees Kelvin) of polymers synthesized, respectively, only from one of the monomers 1, 2, ... n. The T _g values of the homopolymers of most monomers are known and are given, for example, in Ullmann's Ecyclopedia of Industrial Chemistry, Volume 5, Volume A21, p. 169, VCH, Weingheim, 1992; other sources of glass transition temperatures of homopolymers are, for example, J. Brandrup, E.N. Immergut, Polymer Handbook, 1st Edition, J. Wiley, NY 1966, 2nd Edition, J. Wiley, NY 1975, and 3rd Edition, J. Wiley, NY 1989. For ethyl acrylate, a T _g value of −13 ° C. is used.

The actual glass transition temperature can be determined by differential scanning calorimetry (ASTM D 3418-08, the so-called median temperature).

The mass ratio of the number of monomers used in the first stage to the number of monomers used in the second stage is preferably from 5:95 to 50:50.

In preparing the polymer dispersions of the invention, in addition to the above monomers, at least one crosslinking agent can be used. Monomers that have a crosslinking function are compounds with at least two polymerizable ethylenically unsaturated, non-conjugated double bonds in the molecule. Crosslinking can also be carried out, for example, by means of functional groups that can enter into a chemical crosslinking reaction with additional functional groups intended for this purpose. In this case, both additional groups can be attached to the emulsion polymerizate, however, for crosslinking, you can also use a crosslinking agent that can enter into a chemical reaction of crosslinking with the functional groups of the emulsion polymerizate.

Suitable crosslinking agents are, for example, acrylic esters, methacrylic esters, allyl ethers or vinyl ethers of at least dihydric alcohols. In this case, the hydroxyl groups of the alcohols underlying them can be fully or partially converted to ester or ether groups, however, crosslinking agents contain at least two ethylenically unsaturated groups.

Examples of the alcohols underlying these esters are dihydric alcohols such as 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol 1,4-butanediol, but-2-en-1,4-diol, 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,10-decanediol, 1 , 2-dodecandiol, 1,12-dodecandiol, neopentyl glycol, 3-methylpentane-1,5-diol, 2,5-dimethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 1 , 2-cyclohexanediol, 1,4-cyclohexanediol, 1,4-bis (hydroxymethyl) cyclohexane, hydroxypivalic acid and neopentyl glycol monoester, 2.2 bis (4-hydroxyphenyl) propane, 2,2-bis [4- (2-hydroxypropyl) phenyl] propane, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, 3-thiapentane-1,5-diol, and polyethylene glycols, polypropylene glycols and polytetrahydrofurans with a molecular weight of from 200 to 10,000, respectively. In addition to ethylene oxide or propylene oxide homopolymers, block copolymers of ethylene oxide or propylene oxide or copolymers that contain embedded ethylene oxide and propylene can also be used. Seat groups. Examples of the alcohols of these esters containing more than two hydroxyl groups are trimethylolpropane, glycerol, pentaerythritol, 1,2,5-pentantriol, 1,2,6-hexanetriol, cyanuric acid, sorbitol and sugars such as sucrose, glucose and mannose. Obviously, polyhydric alcohols that have been converted with ethylene oxide or propylene oxide can also be used in the form of the corresponding ethoxylates, respectively propoxylates. Polyhydric alcohols can also be first converted by conversion with epichlorohydrin to the corresponding glycidyl ethers.

Other suitable crosslinking agents are vinyl esters or esters of monohydric unsaturated alcohols with ethylenically unsaturated carboxylic acids with 3-6 carbon atoms, for example acrylic acid, methacrylic acid, itaconic acid, maleic acid or fumaric acid. Examples of such alcohols are allyl alcohol, 1-buten-3-ol, 6-hexen-1-ol, 1-octen-3-ol, 9-decen-1-ol, dicyclopentenyl alcohol, 10-undecene-1-ol, cinnamon, citronellol, crotyl alcohol or cis-9-octadecene-1-ol. Monohydric unsaturated alcohols can also be esterified with polybasic carboxylic acids, for example malonic acid, tartaric acid, trimellitic acid, phthalic acid, terephthalic acid, citric acid or succinic acid. A preferred crosslinking agent is allyl methacrylate.

Other suitable crosslinking agents are esters of unsaturated carboxylic acids with the above polyols, for example, oleic acid, crotonic acid, cinnamic acid or 10-undecenoic acid.

In addition, suitable other crosslinking agents are straight or branched, linear or cyclic, aliphatic or aromatic hydrocarbons having at least two double bonds, which in the case of aliphatic hydrocarbons cannot be conjugated, for example, divinylbenzene, divinyltoluene, 1,7-octadiene , 1,9-decadiene, 4-vinyl-1-cyclohexene, trivinylcyclohexane or polybutadiene with a molecular weight of from 200 to 20,000.

Also suitable as crosslinking agents are amides of acrylic acid, amides of methacrylic acid and N-allylamines of at least diatomic amines. Such amines are, for example, 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane, 1,12-dodecandiamine, piperazine, diethylenetriamine or isophorondiamine. Amides from allylamine and unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, itaconic acid and maleic acid, or at least dihydric carboxylic acids, such as those described above, are also suitable.

In addition, triallylamine and triallylmonoalkylammonium salts, for example triallylmethylammonium chloride or triallylmethylammonium methyl sulfate, are suitable as crosslinking agents.

N-vinyl compounds of derivatives of urea, at least diatomic amides, cyanurates or urethanes, for example, urea, ethylene carbamide, propylene carbamide or tartaric acid diamide, for example, N, N'-divinylethylene urea or N, N'-divinylpropylene urea, are also suitable.

Other suitable crosslinking agents are divinyl dioxane, tetraallyl silane or tetravinyl silane.

Obviously, mixtures of the above compounds can also be used. Water-soluble crosslinking agents are preferably used.

In addition, crosslinking monomers include compounds which, in addition to an ethylenically unsaturated double bond, contain a reactive functional group, for example, an aldehyde group, a keto group or an oxirane group, which can react with an added crosslinking agent. Functional groups are preferably keto groups or aldehyde groups. Keto groups or aldehyde groups are preferably joined to the polymer by copolymerization of copolymerizable ethylenically unsaturated compounds with keto groups or aldehyde groups. Suitable compounds of this type are acrolein, methacrolein, vinyl alkyl ketones with 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms in the alkyl radical, formyl styrene, alkyl esters of (meth) acrylic acid with one or two keto groups or aldehyde groups, respectively one aldehyde and one keto group in the alkyl residue, wherein the alkyl residue in total preferably contains from 3 to 10 carbon atoms, for example, the (meth) acryloxyalkylpropanal described in German patent application DE-A-2722097. In addition, N-oxoalkyl (meth) acrylamides, known for example from US patent application US-A-4,226,007 or German patent applications DE-A-2061213 and DE-A-2207209, are also suitable. Particularly preferred are acetoacetyl- (meth) acrylate, acetoacetoxyethyl (meth) acrylate and, in particular, diacetone acrylamide. Crosslinking agents preferably mean compounds with at least two functional groups, in particular with a number of functional groups from 2 to 5, which can undergo a crosslinking reaction with the functional groups of the polymerizate, in particular with keto groups or aldehyde groups. These include, for example, hydrazide, hydroxylamine, oxime ester or amine groups as functional groups for crosslinking keto groups or aldehyde groups. Suitable compounds with hydrazide groups are, for example, polycarboxylic acid hydrazides with a molecular weight of up to 500 g / mol. Particularly preferred hydrazide compounds are dicarboxylic acid dihydrazides, preferably with 2-10 carbon atoms. These include, for example, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide or dihydrazide dihydrazide. Of particular interest are adipic acid dihydrazide, sebacic acid dihydrazide and isophthalic acid dihydrazide. Suitable compounds with hydroxylamine or hydroxyether groups are described, for example, in international application WO 93/25588.

Other suitable crosslinking agents that can be used in both the first and second polymerization stages are, for example, acetoacetoxyalkyl (meth) acrylates, N-vinylpyrrolidone, N- (2-methacryloyloxyethyl) ethylene urea, N- (2-acryloxyethyl) ethylene urea , 2-acetoacetoxyethyl acrylate, 2-acetoacetoxyethyl methacrylate and di-acetone acrylamide.

The crosslinking component is preferably used in an amount of from 0.0005 to 5% by weight, preferably from 0.001 to 2.5% by weight, in particular from 0.01 to 1.5% by weight. in terms of the total weight of the monomers used for the polymerization (including the crosslinking agent). A crosslinking agent can be used both in the first and only in the second stage, or also in both stages.

The radical polymerization of a mixture of monomers (M) can be carried out in the presence of at least one regulator. The regulator is preferably used in an amount of from 0.0005 to 5% by weight, particularly preferably from 0.001 to 2.5% by weight. and, in particular, from 0.01 to 1.5% of the mass. in terms of the total weight of the monomers used for polymerization.

In the general case, compounds with high values of the chain transfer constant are used as regulators (polymerization regulators). The regulator accelerates the chain transfer reaction and at the same time helps to reduce the degree of polymerization of the resulting polymers without affecting the gross reaction rate. Depending on the number of functional groups in a molecule, monofunctional, bifunctional and multifunctional regulators are distinguished, which can lead to the occurrence of one or more chain transfer reactions. Suitable regulators are described in detail, for example, in the manual K.S. Berger und G. Brandrup, J. Brandrup, E.H. Immergut, Polymer Handbook, 3rd Edition, John Wiley & Sons, New York, 1989, p. II / 81-II / 141.

Suitable regulators are, for example, aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, n-butyric aldehyde and isobutyric aldehyde.

In addition, formic acid, its salts or esters such as ammonium formate, 2,5-diphenyl-1-hexene, ammonium hydroxysulfate and ammonium hydroxyphosphate can also be used as a regulator.

Other suitable regulators are halogen compounds, for example, alkyl halides such as carbon tetrachloride, chloroform, bromo-trichloromethane, bromoform, allyl bromide and benzyl compounds, in particular benzyl chloride or benzyl bromide.

Other suitable regulators are allyl compounds, for example, allyl alcohol, functionalized allyl ethers, in particular allyl ethoxylates, alkylallyl ethers or monoallyl ethers of glycerol.

Compounds that contain sulfur in bound form are preferably used as regulators.

Compounds of this type are, for example, inorganic hydrosulfites, bisulfites, dithionites or organic sulfides, di-sulfides, polysulfides, sulfoxides and sulfones. These include di-n-butyl sulfide, di-n-octyl sulfide, diphenyl sulfide, thiodiglycol, ethylthioethanol, diisopropyl disulfide, di-n-butyl disulfide, di-n-hexyl disulfide, diacetyl disulfide, di-sulfide di-sulfide, di-sulfide, di and / or diaryl sulfide.

Suitable other polymerization regulators, in addition, are thiols (compounds containing sulfur as an SH group, also called mercaptans). Preferred regulators are monofunctional, bifunctional and polyfunctional mercaptans, mercaptoalcohols and / or mercaptocarboxylic acids. Examples of such compounds are allylthioglycolates, ethylthioglycolate, cysteine, 2-mercaptoethanol, 1,3-mercaptopropanol, 3-mercaptopropane-1,2-diol, 1,4-mercaptobutanol, mercaptoacetic acid, 3-mercaptopropionic acid, 3-mercaptopropionic acid, 3-mercaptopropanoic acid, 3-mercaptopropanoic acid acid, thiourea and alkyl mercaptans such as n-butyl mercaptan, n-hexyl mercaptan, tert-dodecyl mercaptan and n-dodecyl mercaptan.

Examples of bifunctional regulators that contain two sulfur atoms in bound form are bifunctional thiols, for example, dimercaptopropanesulfonic acid (sodium salt), dimercaptosuccinic acid, dimercapto-1-propanol, dimercaptol-octophenol-buto-colo-buto-colo-buto-colo-buto-colo-buto-colo- Examples of multifunctional regulators are compounds that contain more than two sulfur atoms in bound form. Suitable examples are trifunctional and / or tetrafunctional mercaptans.

All of the above regulators can be used individually or in combination with each other. In a particular embodiment, polymer dispersions are prepared by radical emulsion polymerization without the addition of a regulator.

To obtain polymers, monomers can be polymerized using radical-forming initiators.

Typical peroxo and / or azo compounds, for example, alkali metal or ammonium peroxydisulfates, diacetyl peroxide, dibenzoyl peroxide, succinyl peroxide, di-tert-butyl peroxide, tert-butyl perbenzoate, tert-butyl perpivalate, can be used as initiators of radical polymerization. , tert-butylperoxy-2-ethylhexanoate, tert-butyl permaleate, cumene hydroperoxide, diisopropyl peroxydicarbamate, bis (o-toluoyl) peroxide, didecanoyl peroxide, dioctanoyl peroxide, dilauroyl peroxide, tert-butyl perisobutyrate , tert-butyl peracetate, di-tert-amyl peroxide, tert-butyl hydroperoxide, azobisisobutyronitrile, 2,2'-azobis (2-amidino-propane) dihydrochloride or 2,2'-azobis (2-methylbutyronitrile). Mixtures of these initiators are also suitable.

Reduction / oxidation systems (red / oxy initiator systems) can also be used as initiators. Red / oxy initiator systems consist of at least one, most often inorganic reducing agent and one inorganic or organic oxidizing agent (oxidizing agent). By an oxidizing component is meant, for example, the above emulsion polymerization initiators. By reducing components are meant, for example, alkali metal salts with sulphurous acid, for example sodium sulfite, sodium hydrosulfite, alkali metal salts with sulphurous acid, in particular sodium disulfite, products of the addition of aliphatic aldehydes and ketones to bisulfite, in particular acetone bisulfite or a reducing agent, in particular hydroxymethanesulfinic acid and its salts, or ascorbic acid. Red / oxy initiator systems can be used in conjunction with soluble metal compounds, the metal component of which may have several degrees of valency. Conventional ed / ox initiator systems include, for example, ascorbic acid / iron (II) sulfate / sodium peroxodisulfate, tert-butyl hydroperoxide / sodium disulfite, tert-butyl hydroperoxide / sodium hydroxymethanesulfinic acid. The individual components, for example, reducing components, can also be mixtures, for example, a mixture of sodium salt with hydroxymethanesulfinic acid and sodium disulfite.

The number of initiators in the General case is from 0.1 to 10 wt. -%, preferably from 0.1 to 5 wt. -%, in terms of all monomers to be polymerized. In emulsion polymerization, several different initiators can also be used.

A polymer dispersion is usually prepared in the presence of at least one surfactant. A detailed description of suitable protective colloids is given in Houben-Weyl, Methoden der organischen Chemie, Volume XIV / 1, Makromolekulare Stoffe, Georg Thieme, Stuttgart, 1961, cc. 411-420. Suitable emulsifiers are also described in Houben-Weyl, Methoden der organischen Chemie, Volume 14/1, Makromolekulare Stoffe, Georg Thieme, Stuttgart, 1961, cc. 192-208.

Suitable emulsifiers are both anionic and cationic and nonionic emulsifiers. Emulsifiers are preferably used as surfactants, the relative molecular weight of which is usually lower than the molecular weight of the protective colloids.

Suitable nonionic emulsifiers are arylaliphatic or aliphatic nonionic emulsifiers, for example, ethoxylated monoalkylphenols, dialkylphenols and trialkylphenols (degree of ethoxylation from 3 to 50, alkyl radicals with 4-10 carbon atoms), ethoxylates of long chain alcohols (degree of ethoxylation from 3 to 100, ethoxylation from 3 to 100, ethoxylation 8-36 carbon atoms), as well as homopolymers and copolymers of ethylene oxide and propylene oxide. Alkylene oxide units can be distributed statistically or in blocks. Well suited are, for example, ethylene oxide / propylene oxide block copolymers. Long chain alkanol ethoxylates are preferred (an alkyl residue with 1-30 carbon atoms, an average degree of ethoxylation from 5 to 100), of which ethoxylates with an unbranched alkyl residue with 12-20 carbon atoms and an average degree of ethoxylation from 10 to 50 are used, and also ethoxylated monoalkylphenols.

Suitable anionic emulsifiers are, for example, alkali and ammonium salts of alkyl sulfates (an alkyl residue with 8-22 carbon atoms), acidic sulfuric esters with ethoxylated alkanols (degree of ethoxylation from 2 to 50, an alkyl residue with 12-18 carbon atoms) and ethoxylated alkyl phenols (degree of ethoxylation from 3 to 50, an alkyl residue with 4-9 carbon atoms), alkyl sulfonic acids (an alkyl residue with 12-18 carbon atoms) and alkylaryl sulfonic acids (an alkyl residue with 9-18 carbon atoms). Other suitable emulsifiers are given in Houben-Weyl, Methoden der organischen Chemie, Volume XIV / 1, Makromolekulare Stoffe, Georg-Thieme, Stuttgart, 1961, cc. 192-208). Suitable anionic emulsifiers are also bis (phenylsulfonic acid) esters, respectively, their alkali or ammonium salts, one or both aromatic rings of which contain an alkyl group with 4-24 carbon atoms. These compounds are known, for example, from US patent application US-A 4,269,749 and are commercially available products (for example, Dowfax® 2A1 from Dow Chemical Company).

Suitable cationic emulsifiers are preferably quaternary ammonium halides, for example trimethylacetyl ammonium chloride, methyltrioctylammonium chloride, benzyltriethylammonium chloride or quaternary compounds of N-alkylpyridines, N-morpholines or N-imidazoles with 6-20 carbon atoms, for example, lauride-pyridine chloride.

The approximate amount of emulsifier in the General case is from 0.01 to 10 wt. -%, preferably from 0.1 to 5% of the mass. in terms of the number of monomers to be polymerized.

The neutralization of the acid groups of the first polymerizate is preferably carried out by adding at least part of the neutralizing substance during the polymerization of the second stage, and the neutralizing substance is preferably supplied in parallel with the supply of monomers. In this case, the neutralizing substance can be added together with the monomers to be polymerized or in a separate stream. Upon completion of the supply of all monomers in the polymerization vessel, at least 10%, preferably from 30 to 100%, or from 30 to 90% of acid equivalents of the amount of neutralizing agent necessary to neutralize is preferably present.

Emulsion polymerization is usually carried out in the temperature range from 30 to 130 ° C, preferably from 50 to 95 ° C. The polymerization medium may consist only of water or from mixtures of water with liquids miscible with it, such as methanol. Preferably, only water is used. Emulsion polymerization of the first stage can be carried out both in a batch mode and in a continuous feed mode, including a stepwise or gradient mode. For better particle size control during polymerization, a seed polymer is preferably charged.

The procedure for adding the initiator to the polymerization vessel during the process of radical aqueous emulsion polymerization is known to those skilled in the art. The initiator can be completely loaded into the polymerization vessel or continuously or stepwise used in the process of radical aqueous emulsion polymerization as it is consumed. This depends, in particular, on the chemical nature of the initiating system, as well as on the polymerization temperature. A portion of the initiator is preferably charged into the polymerization vessel, and the remainder is fed to the polymerization zone as it is consumed. To remove residual monomers, the initiator is usually also added at the end of direct emulsion polymerization, that is, when the degree of conversion of the monomers is at least 95%. Individual components in the case of a constant supply can be added to the reactor from above, from the side or from below through the bottom of the reactor.

As a result of emulsion polymerization, aqueous polymer dispersions are obtained, the solids content of which is usually from 15 to 75% by mass, preferably from 40 to 75% by mass, particularly preferably greater than or equal to 50% by mass. To achieve a high yield calculated per unit volume of reactor per unit time, dispersions with the highest possible solids content are preferred. To achieve a solids content of more than 60% of the mass. it is necessary to establish a bimodal or multimodal particle size distribution, since otherwise the dispersion has too high viscosity and is inconvenient to handle. Re-generated particles can be obtained, for example, by adding a seed polymer (see European patent EP 81083), an excess of an emulsifier or microemulsions. Another advantage achieved due to the low viscosity of the dispersion at a high solids content is the improved coating properties at high solids. The formation of new (s) generations) of particles can be carried out at any time. It is determined by the size distribution of the particles, which is necessary to achieve a low viscosity.

Often, it is often preferable to further treat the aqueous polymer dispersion obtained at the end of the polymerization steps in order to reduce the residual monomer content. Such additional processing is carried out chemically, for example, by supplementing the polymerization reaction by using a more efficient system of radical initiators (the so-called post-polymerization) and / or physically, for example, by steaming the aqueous polymer dispersion with water vapor or an inert gas. Appropriate chemical and / or physical methods are known to those skilled in the art [see, for example, European patent application EP-A 771328, as well as German patent applications DE-A 19624299, DE-A 19621027, DE-A 19741184, DE-A 19741187, DE -A 19805122, DE-A 19828183, DE-A 19839199, DE-A 19840586 and DE-A 19847115]. Moreover, the combination of chemical and physical methods of additional processing provides the advantage that, in addition to unconverted ethylenically unsaturated monomers, other interfering volatile organic components (the so-called volatile organic components) are also removed from the aqueous polymer dispersion.

In one embodiment of the invention, silane monomers are used in both stages, for example, such as vinyltrialkoxysilanes, in particular vinyltrimethoxysilane, alkylvinyl dialkoxysilanes, for example, methylvinyl dialkoxysilanes, or (meth) acryloxyalkyltrialkoxymethyloxytrilethoxymethyrylmethoxymethylmethyl) acrylmethoxymethylmethylmethyl) These silane monomers can be used in amounts of up to 2% by weight, preferably from 0.05 to 1% by weight. in terms of the total mass of monomers.

The aqueous polymer dispersions obtained by the method of the invention comprise polymerizate particles that have a mass average diameter D _w in the range of ≥50 to ≤500 nm, preferably from ≥70 to ≤300 nm, in particular preferably from ≥80 to ≤200 nm. Known to specialists, the determination of the mass-average particle diameter is carried out, for example, by analytical ultracentrifugation. By mass-average particle diameter in the present description is meant the mass-average value D _w50 determined by analytical ultracentrifugation (see SE Harding et al., Analytical Ultracentrifugation in Biochemistry and Polymer Science, Royal Society of Chemistry, Cambridge, Great Britain 1992, chapter 10, Analysis of Polymer Dispersions with an Eight-Cell-AUC-Multiplexer: High Resolution Particle Size Distribution and Density Gradient Techniques, W. Mächtle, cc. 147-175).

In addition, from the inventive aqueous polymer dispersions by simple methods (for example, by freezing or spray drying), the corresponding polymer powders can be obtained. The polymer powders available according to the invention can also be used as a component in the preparation of coating agents for organic substrates, as well as for the modification of mineral binders.

The solids content in aqueous polymer dispersions is usually from 20 to 70% by weight, preferably from 40 to 65% by weight.

The aqueous dispersion of the polymerizate in accordance with the method proposed in the invention can be used either by itself or with additives that preserve the mineral molded product (for example, fiber cement boards). Such an additive may be aromatic ketone, in particular benzophenone, used according to German patent application DE-A 3827975 as a photoinitiator for crosslinking when exposed to electromagnetic radiation, or water-soluble dihydrazide, if according to German patent application DE-A 3901073, the polymerizate contains monomeric links with carbonyl groups.

In addition, aqueous preparations suitable for use according to the invention may also contain crosslinking additives. Such crosslinking additives can be aromatic ketones, for example, alkyl phenyl ketones, the phenyl ring of which optionally contains one or more substituents, or benzophenone and substituted benzophenones as photoinitiators. Suitable photoinitiators for this purpose are known, for example, from German patent application DE-A 3827975 and European patent application EP-A 417568. Suitable compounds with a crosslinking action are also water-soluble compounds with at least two amino groups, for example, dihydrazides of aliphatic dicarboxylic acids according to German patent application DE-A 3901073, if the copolymer contains monomer units with carbonyl groups.

In a preferred embodiment of the present invention, the aqueous preparations are used as a colorless varnish. In such a case, they usually contain (in terms of their total weight) from 10 to 60 wt. -%, preferably from 40 to 55% of the mass. at least one copolymer P and from 0.1 to 30 wt. -%, preferably from 0.5 to 10% of the mass. conventional auxiliary component, in particular, antifoam and / or film-forming component.

In another embodiment of the present invention, aqueous preparations are used in the form of pigment and / or bulking preparations. In such a case, the total content of the copolymer in the aqueous preparation is in the range from 10 to 60 wt. -%, preferably from 20 to 40 wt. -%, the content of the auxiliary component in the range from 0.1 to 30 wt. -%, preferably from 0.5 to 10% of the mass., And the content of fillers and / or pigments in the range from 10 to 60% of the mass., In particular, from 15 to 40% of the mass .. The number of pigments and / or fillers in the General case is from 50 to 450 mass.h . per 100 parts by weight copolymer P in an aqueous preparation. In addition, in pigment-containing preparations, in addition to the film-forming components and anti-foaming agents, a dispersing or wetting agent is also preferably present.

An aqueous dispersion of the polymerizate in pigmented form is especially often used for preservation. Typical white pigments are, for example, titanium dioxide (preferably in rutile form), barium sulfate, zinc oxide or lithopones (zinc sulfide + barium sulfate). Used for decorative purposes, preparations may also contain colored pigments, for example, iron oxides, carbon black, graphite, yellow zinc crowns, green zinc crowns, ultramarine, manganese black, antimony black, manganese violet, Paris blue or Swiss green.

Furthermore, for example, barium sulfate, talc, mica, calcium carbonate, dolomite, silica flour and the corresponding mixtures can be used as pigments (often also called fillers).

The colorless varnishes and pigmented paints of the invention may contain the usual amounts of other conventional auxiliary components, for example, wetting agents, preservatives for containers and films, thickeners, antifoams, fungicides, algaecides, spreading agents and anti-freeze agents.

The amount of dispersant used is typically from 0.5 to 6% by weight, preferably from 1 to 3% by weight. in terms of the number of monomers subject to radical polymerization.

The weight of the aqueous polymer preparation to be applied for preservation purposes is usually from 50 to 400 g / m ² (based on the wet preparation). The application of the drug can be carried out by known methods by spraying, puttying, by means of a squeegee or roll, or by spraying. An important circumstance is that the method proposed in the invention can be used both in the case of already hardened and freshly prepared ("green") mineral molded products, such as fiber cement boards. Sometimes after curing, additional coating composition is applied and subsequently dried.

Examples

1) Comparative dispersion (theoretical T _g 44 ° C)

In a polymerization vessel equipped with a metering device and a temperature control system, load the preliminary mixture:

402.1 g water 13.26 g A 20 percent aqueous solution of fatty alcohol ethoxylate with 16-18 carbon atoms and 8.71 g 45% dodecyldiphenyl oxide disulfonic acid sodium salt

In the supply vessel, an emulsion is prepared from the following components:

560.2 g water 19.89 g 20 percent aqueous solution of fatty alcohol ethoxylate with 16-18 carbon atoms 34.85 g 45% dodecyldiphenyl oxide disulfonic acid sodium salt 5.23 g 50% aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid 13.07 g 50 percent aqueous acrylamide solution 392.0 g n-butyl acrylate and 908.2 g methyl methacrylate

In the third feed vessel carry out the preparation of the feed stream 3:

56.00 g 7% sodium peroxodisulfate aqueous solution

The pre-mixture without a 50% aqueous solution of 2-acryl-amido-2-methylpropanesulfonic acid is heated to an external temperature of 95 ° C (polymerization temperature 90 ° C; stirring speed 150 rpm). A 50% aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid was added and the reagents were stirred for 15 minutes. Then feed stream 1 and feed stream 2 are initiated. Feed stream 1 is dosed for three hours, feed stream 2 for 3.5 hours. The stirring speed is reduced to 100 rpm and stirring is continued for the next 30 minutes.

Within 30 minutes, 11.7 g of a 10% aqueous solution of tert-butyl hydroperoxide and 9.1 g of a 10% aqueous solution of hydroxymethanesulfinic acid are dosed. 2.61 g of a 5% aqueous solution of hydrogen peroxide were added and the reagents were stirred for 10 minutes. After cooling, the mixture was neutralized with 1.57 g of 25% aqueous ammonia and 161.77 water was added. 2620 g of a 51.6% aqueous dispersion is obtained.

2) Comparative dispersion (two-stage: without the monomer I proposed in the invention)

In a polymerization vessel equipped with a metering device and a temperature control system, load the preliminary mixture:

389.7 g water and 51.07 g polystyrene seed latex (33% in water)

In the first feed vessel, emulsion of feed stream 1 is prepared from the following components:

323.9 g water 9.7 g 20 percent aqueous solution of fatty alcohol ethoxylate with 16-18 carbon atoms 23.15 g 28 percent sodium lauryl polyethoxysulfate aqueous solution 9.07 g 50 percent aqueous solution of acrylic acid, 462.3 g n-butyl acrylate and 178.8 g methyl methacrylate

In the second feed vessel, emulsion of feed stream 2 is prepared from the following components:

320.7 g water 9.7 g 20 percent aqueous solution of fatty alcohol ethoxylate with 16-18 carbon atoms 23.15 g 28 percent sodium lauryl polyethoxysulfate aqueous solution 10.37 g 50 percent aqueous acrylamide solution 9.07 g 50 percent aqueous acrylic acid solution 210.0 g n-butyl acrylate and 431.0 g methyl methacrylate

In the third feed vessel carry out the preparation of the feed stream 3:

55.6 g 7% sodium peroxodisulfate aqueous solution

The pre-mixture is heated to an external temperature of 90 ° C (polymerization temperature 83 ° C, stirring speed 150 rpm). Feed flows 1 and 3 are simultaneously initiated. Feed stream 1 is dosed for 1.5 hours, after which feed stream 2 is dosed for 1.5 hours. Feed stream 3 is dosed for three hours. Over the next 30 minutes, the components are mixed, and then within one hour, 11.7 g of a 10% aqueous solution of tert-butyl hydroperoxide and 9.1 g of a 10% aqueous solution of hydroxymethanesulfinic acid are metered. After that, the mixture is neutralized with 55.09 g of a 2% aqueous solution of sodium hydroxide, stirred for 10 minutes, reduced the stirring speed to 100 rpm and cooled. Then add 2.6 g of a 5% aqueous solution of hydrogen peroxide, as well as 78.78 g of water. 2674 g of a 49.9 percent dispersion is obtained.

3) An example of a monomer-containing I (two-stage) dispersion according to the invention

In a polymerization vessel equipped with a metering device and a temperature control system, load the preliminary mixture:

389.7 g water and 51.07 g polystyrene seed latex (33% in water)

In the first feed vessel, emulsion of feed stream 1 is prepared from the following components:

323.9 g water 9.7 g 20 percent aqueous solution of fatty alcohol ethoxylate with 16-18 carbon atoms 23.15 g 28 percent sodium lauryl polyethoxysulfate aqueous solution 9.07 g 50% aqueous solution of 2-acrylamido-2-methylpropane-sulfonic acid 462.3 g n-butyl acrylate and 178.8 g methyl methacrylate

In the second feed vessel, emulsion of feed stream 2 is prepared from the following components:

320.7 g water 9.7 g 20 percent aqueous solution of fatty alcohol ethoxylate with 16-18 carbon atoms 23.15 g 28 percent sodium lauryl polyethoxysulfate aqueous solution 10.37 g 50 percent aqueous acrylamide solution 9.07 g 50% aqueous solution of 2-acrylamido-2-methylpropane-sulfonic acid 210.0 g n-butyl acrylate and 431.0 g methyl methacrylate

In the third feed vessel carry out the preparation of the feed stream 3:

55.6 g 7 percent aqueous solution of sodium peroxodisulfate.

The pre-mixture is heated to an external temperature of 90 ° C (polymerization temperature 83 ° C, stirring speed 150 rpm). Feed flows 1 and 3 are simultaneously initiated. Feed 1.5 is dosed for 1.5 hours and feed 2 is dosed for the next 1.5 hours. Feed 3 is dosed for three hours. The mixture is stirred for 30 minutes for one hour 11.7 g of a 10% aqueous solution of tert-butyl hydroperoxide and 9.1 g of a 10% aqueous solution of hydroxymethanesulfinic acid are metered in. The mixture is then neutralized with 55.09 g of a 2% aqueous solution of sodium hydroxide, stirred for 10 minutes, the stirring speed is reduced to 100 rpm and cooled. 2.6 g of a 5% aqueous hydrogen peroxide solution are added, as well as 78.78 g of water. 2674 g of a 49.9 percent dispersion is obtained.

4) An example of a monomer-containing I (two-stage) dispersion according to the invention (excess solid phase)

In a polymerization vessel equipped with a metering device and a temperature control system, load the preliminary mixture:

389.7 g water and 51.07 g polystyrene seed latex (33% in water)

In the first feed vessel, emulsion of feed stream 1 is prepared from the following components:

129.6 g water 3.89 g 20 percent aqueous solution of fatty alcohol ethoxylate 16-18 carbon atoms 9.26 g 28 percent sodium lauryl polyethoxysulfate aqueous solution 3.63 g 50% aqueous solution of 2-acrylamido-2-methylpropane-sulfonic acid 184.9 g n-butyl acrylate and 71.50 g methyl methacrylate

In the second feed vessel, emulsion of feed stream 2 is prepared from the following components:

515.0 g water 15.56 g 20 percent aqueous solution of fatty alcohol ethoxylate with 16-18 carbon atoms 37.04 g 28 percent sodium lauryl polyethoxysulfate aqueous solution 10.37 g 50 percent aqueous acrylamide solution 14.52 g 50% aqueous solution of 2-acrylamido-2-methylpropane-sulfonic acid 336.0 g n-butyl acrylate and 689.6 g methyl methacrylate

In the third feed vessel carry out the preparation of the feed stream 3:

55.6 g 7% sodium peroxodisulfate aqueous solution

The pre-mixture is heated to an external temperature of 90 ° C (polymerization temperature 83 ° C, stirring speed 150 rpm). Feed flows 1 and 3 are simultaneously initiated. Feed 36 is dosed for 36 minutes and feed 2 is dosed for the next 2 hours and 24 minutes. Feed 3 is dosed for three hours. Then the components are mixed for 30 minutes and for the next hour 11.7 g of a 10% aqueous solution of tert-butyl hydroperoxide and 9.1 g of a 10% aqueous solution of hydroxymethanesulfinic acid are metered in. The mixture is then neutralized with 55.09 g of a 2% aqueous solution of sodium hydroxide, stirred for 10 minutes, the stirring speed is reduced to 100 rpm and the mixture is cooled. 2.6 g of a 5% aqueous solution of hydrogen peroxide and 78.78 g of water are added. 2674 g of a 49.7 percent dispersion is obtained.

5) An example of a (two-stage) dispersion according to the invention with monomers I, a regulator and a crosslinking agent

In a polymerization vessel equipped with a metering device and a temperature control system, load the preliminary mixture:

389.7 g water and 51.07 g polystyrene seed latex (33% in water)

In the first feed vessel, emulsion of feed stream 1 is prepared from the following components:

327.2 g water 9.7 g 20 percent aqueous solution of fatty alcohol ethoxylate with 16-18 carbon atoms 23.15 g 28 percent sodium lauryl polyethoxysulfate aqueous solution 5.19 g 50 percent aqueous acrylamide solution 9.07 g 50% aqueous solution of 2-acrylamido-2-methylpropane-sulfonic acid 3.24 g 3-methacryloxypropyltrimethoxysilane 465.4 g n-butyl acrylate and 175.7 g methyl methacrylate

In the second feed vessel, emulsion of feed stream 2 is prepared from the following components:

331.7 g water 9.7 g 20 percent aqueous solution of fatty alcohol ethoxylate with 16-18 carbon atoms 23.15 g 28 percent sodium lauryl polyethoxysulfate aqueous solution 5.19 g 50 percent aqueous acrylamide solution 9.07 g 50% aqueous solution of 2-acrylamido-2-methylpropane-sulfonic acid 7.78 g tert-dodecyl mercaptan 1.30 g allyl methacrylate 3.24 g 3-methacryloxypropyltrimethoxysilane 207.5 g n-butyl acrylate and 432.2 g methyl methacrylate

In the third feed vessel carry out the preparation of the feed stream 3:

55.6 g 7% sodium peroxodisulfate aqueous solution

The pre-mixture is heated to an external temperature of 90 ° C (polymerization temperature 83 ° C, stirring speed 150 rpm). Feed flows 1 and 3 are simultaneously initiated. Feed 1.5 is dosed for 1.5 hours and feed 2 is fed over the next 1.5 hours. Feed 3 is dosed for three hours. The reactants are mixed for 30 minutes and then for 11.7 g of a 10% aqueous solution of tert-butyl hydroperoxide and 9.1 g of a 10% aqueous solution of hydroxymethanesulfinic acid are metered in one hour. The mixture is then neutralized with 55.09 g of a 2% aqueous solution of sodium hydroxide, stirred for 10 minutes, the stirring speed is reduced to 100 rpm and the mixture is cooled. 2.6 g of a 5% aqueous solution of hydrogen peroxide and 69.18 g of water are added. Obtain 2703 g of a 49.9 percent dispersion.

Technical Applicability Test

Carry out a test of the technical applicability of the wet coating (evaluation after 5 days + steam at a temperature of 60 ° C).

To determine the suitability of the dispersion for technical use, paints are prepared in accordance with the following recipe:

92 g of water

0.5 g tylose 30000YP2 (ShinEtsu Tylose GmbH & Co. KG, Wiesbaden),

0.5 g of ammonia (25 percent),

15 g of ultradispersion MD20 (dispersant company BASF SE, Ludwigshafen),

3 g BYK 024 (antifoam firm Byk Chemie, Wesel),

30.2 g of titanium dioxide (Kronos 2310 from Kronos International Inc., Leverkusen),

173.2 g of black iron oxide,

26.5 g of calcium carbonate (Omyacarb 850 OG from Omya GmbH, Cologne),

595.8 g of a binder dispersion,

8.5 g of water

15 g of Dowanol DPnB company Dow Chemical Germany (Schwalbach),

24 g of a wax dispersion (Michem Lube 368.E from Michelman Inc., Chaplain, Luxembourg),

8 g of Acticide MKB3 from Thor GmbH (Speyer).

Paints are applied by spraying onto pre-heated, cured fiber cement boards (weight of the applied layer is about 10 g).

Then, the coated fiber cement board was dried at 80 ° C for 30 minutes. After drying, the coated fiber cement plate for five days is laid face down in a water bath at a temperature of 60 ° C.

Immediately after removing the wet cement fiberboard from the water bath, the degree of its whiteness is evaluated:

1 lack of whiteness,

2 insignificant amount of white dots,

3 small amount of white spots,

4 several large white areas,

5 whitish surface.

After drying, the degree of fading is visually assessed. Assessment of fading is performed in accordance with the following scale:

0 lack of fading,

1 fading is almost absent

2 fading,

3 moderate fading,

4 strong fading,

5 very strong fading.

To determine the color change of the coated fiber cement boards after atmospheric exposure, the difference in brightness between the exposed and non-exposed areas is visually evaluated. For assessment use a scale from 0 to 2 points:

0 no difference,

1 faint difference,

2 strongly noticeable difference.

The control of the “visual impression” gives an idea of the quality of the coating as a whole without prior exposure to the load: the uniform, slightly shiny appearance of the covered roof tiles without defective areas is important.

Adhesion test

Paints are applied by spraying onto pre-heated, cured fiber cement boards (weight of the applied layer is about 10 g). Then, the coated fiber cement board was dried at 80 ° C for 30 minutes. After drying, two coated fiber cement plates are laid on top of each other, after which a load of 180 kilograms is applied to a 10 × 10 cm area for 24 hours at 50 ° C. After cooling to room temperature, they try to separate the plates from each other.

0 test samples are separated from each other without any effort,

1 test samples can be separated from each other without the use of force,

2 test samples can be separated from each other with little effort,

3 test samples can be separated from each other using more significant force,

4 test samples can be separated from each other with considerable effort,

5 test samples cannot be separated from each other.

Table 1 Testing the technical applicability of fiber cement boards (b - with load, u - without load) Example Color difference between b and u after drying Whiteness Fading Visual impression Adhesion test Comparative Example 1 2 3 2 Mediocre (spotting) 2.5 Reference Example 2 1-2 2 1-2 Favorable-mediocre 2 3 0 0-1 0 Favorable 1,5 four 0 0 0 Favorable one 5 0 0 0 Favorable one

Weather Resistance Test

The weathering test of paints on fiber cement boards is carried out by means of a xenon test according to DIN EN ISO 11341 (cycle A) for paints and varnishes and compared with a standard after 500 hours. In accordance with this test, coated 5 × 13 cm fiber cement boards are alternately illuminated for 102 minutes in a dry state and for 18 minutes when moistened with a thin water mist. The test is performed at a relative humidity of 50% and a standard temperature of 65 ° C. The density of irradiation with ultraviolet light is 60 W at a wavelength of 300 to 400 nm or 0.51 W / (m ² · nm) at 340 nm.

As criteria for paint dysfunction, its visible damage, in particular, cracks or peeling, color changes and loss of gloss, is evaluated. The gloss of the paint is measured before and after atmospheric exposure using a gloss meter at an angle of Bragg reflection of 60 °.

The xenon test results, respectively, after 1,500 hours of testing:

comparative example 1: strong loss of gloss, the first small cracks are noticeable, loss of gloss of 70%,

comparative example 2: visible loss of gloss (50%),

example 3: slight loss of gloss (20%),

example 4: the absence of a noticeable loss of gloss (0%),

Example 5: slight loss of gloss (15%).

Claims (13)

1. An aqueous multi-stage dispersion of polymerizates obtained by radically initiated aqueous emulsion polymerization, which contains a soft and a solid phase and the ratio of solid phase to soft phase is 25-95% wt. to 75-5% wt., and the glass transition temperature (T _g ) of the soft phase as the first stage is from -30 to 0 ° C, while T _{g of the} solid phase as the second stage is from 20 to 60 ° C, and wherein the dispersion contains units of at least one monomer of the general formula (I):

wherein
n means a number from 0 to 2,
R1, R2, R3 independently from each other mean hydrogen or methyl group,
X is oxygen or NH,
Y is hydrogen, alkali metal or NH ₄ ,
characterized in that the polymerizate of the first stage is a copolymer:
(i) which is used in an amount of from 5 to 50% wt. in terms of 100 parts by weight all monomers to be polymerized in the first and second stages, and
(ii) which is synthesized from at least 80% wt. and up to 99% wt. basic monomers selected from the group consisting of alkyl (meth) acrylates with 1-10 carbon atoms, amides and hydroxyalkyl esters of α, β-unsaturated carboxylic acids with 3-6 carbon atoms, and mixtures of these monomers, and
(iii) which contains at least 0.1% wt. and up to 5% wt. monomers (I). 2. An aqueous dispersion of polymers according to claim 1, characterized in that said copolymer contains acrylamide as the main monomers. 3. An aqueous dispersion of polymers according to claim 1, characterized in that said copolymer contains, as main monomers, a mixture of n-butyl acrylate, methyl methacrylate and acrylamide. 4. An aqueous dispersion of polymers according to claim 1, characterized in that said copolymer contains 2-acrylamido-2-methylpropanesulfonic acid as monomer (I). 5. The aqueous dispersion of polymers according to claim 1, characterized in that T _{g of} its soft phase as a first stage is from -20 to 0 ° C, while T _{g of} its solid phase as a second stage is from 30 to 50 ° C. 6. Aqueous dispersion of polymerizates according to one of paragraphs. 1-5, characterized in that at both stages using a silane monomer. 7. The aqueous dispersion of the polymers of claim. 6, characterized in that the silane monomer is a vinyl-trialkoxysilanes such as vinyl trimethoxysilane, alkilvinildialkoksisilany, metilvinildialkoksisilan or (meth) akriloksialkiltrialkoksisilany such as (meth) akriloksipropiltrimetoksisilan and (meth) acryloxy-propyltriethoxysilane. 8. An aqueous dispersion of polymers according to claim 7, characterized in that the silane monomer is used in an amount of up to 2% wt. in terms of the total mass of monomers. 9. The use of an aqueous dispersion of polymerizates according to one of claims. 1-8 as a coating agent. 10. The use of an aqueous dispersion of polymerizates according to one of paragraphs. 1-8 as a binder. 11. The use of an aqueous dispersion of polymerizates according to one of paragraphs. 1-8 as an additive for mineral or non-mineral substances. 12. Mineral molded products, the coating of which contains an aqueous dispersion of polymerizates according to one of paragraphs. 1-8. 13. Fiber cement boards, the coating of which contains an aqueous dispersion of polymerizates according to one of claims. 1-8.